From dd986e8b547c0dde924c4b566ad0894ad4f1beb9 Mon Sep 17 00:00:00 2001 From: Ivo De Decker Date: Sat, 6 Dec 2014 18:58:19 +0000 Subject: pcre3 (2:8.35-3.3) unstable; urgency=medium * Non-maintainer upload. * Upstream patch for heap buffer overflow, CVE-2014-8964, taken from 1:8.36-1 (Closes: #770478) Thanks to Salvatore Bonaccorso for the reminder. # imported from the archive --- doc/html/NON-AUTOTOOLS-BUILD.txt | 764 ++ doc/html/README.txt | 991 +++ doc/html/index.html | 185 + doc/html/pcre-config.html | 109 + doc/html/pcre.html | 213 + doc/html/pcre16.html | 384 + doc/html/pcre32.html | 382 + doc/html/pcre_assign_jit_stack.html | 76 + doc/html/pcre_compile.html | 111 + doc/html/pcre_compile2.html | 115 + doc/html/pcre_config.html | 92 + doc/html/pcre_copy_named_substring.html | 65 + doc/html/pcre_copy_substring.html | 61 + doc/html/pcre_dfa_exec.html | 129 + doc/html/pcre_exec.html | 111 + doc/html/pcre_free_study.html | 46 + doc/html/pcre_free_substring.html | 46 + 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doc/html/pcrelimits.html | 90 + doc/html/pcrematching.html | 242 + doc/html/pcrepartial.html | 509 ++ doc/html/pcrepattern.html | 3235 ++++++++ doc/html/pcreperform.html | 195 + doc/html/pcreposix.html | 290 + doc/html/pcreprecompile.html | 163 + doc/html/pcresample.html | 110 + doc/html/pcrestack.html | 225 + doc/html/pcresyntax.html | 538 ++ doc/html/pcretest.html | 1158 +++ doc/html/pcreunicode.html | 262 + doc/index.html.src | 185 + doc/pcre-config.1 | 92 + doc/pcre-config.txt | 86 + doc/pcre.3 | 218 + doc/pcre.txt | 10423 ++++++++++++++++++++++++ doc/pcre16.3 | 371 + doc/pcre32.3 | 369 + doc/pcre_assign_jit_stack.3 | 59 + doc/pcre_compile.3 | 96 + doc/pcre_compile2.3 | 101 + doc/pcre_config.3 | 77 + doc/pcre_copy_named_substring.3 | 51 + doc/pcre_copy_substring.3 | 47 + doc/pcre_dfa_exec.3 | 118 + doc/pcre_exec.3 | 99 + doc/pcre_free_study.3 | 31 + doc/pcre_free_substring.3 | 31 + doc/pcre_free_substring_list.3 | 31 + doc/pcre_fullinfo.3 | 93 + doc/pcre_get_named_substring.3 | 54 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doc/perltest.txt (limited to 'doc') diff --git a/doc/html/NON-AUTOTOOLS-BUILD.txt b/doc/html/NON-AUTOTOOLS-BUILD.txt new file mode 100644 index 0000000..cddf3e0 --- /dev/null +++ b/doc/html/NON-AUTOTOOLS-BUILD.txt @@ -0,0 +1,764 @@ +Building PCRE without using autotools +------------------------------------- + +This document contains the following sections: + + General + Generic instructions for the PCRE C library + The C++ wrapper functions + Building for virtual Pascal + Stack size in Windows environments + Linking programs in Windows environments + Calling conventions in Windows environments + Comments about Win32 builds + Building PCRE on Windows with CMake + Use of relative paths with CMake on Windows + Testing with RunTest.bat + Building under Windows CE with Visual Studio 200x + Building under Windows with BCC5.5 + Building using Borland C++ Builder 2007 (CB2007) and higher + Building PCRE on OpenVMS + Building PCRE on Stratus OpenVOS + Building PCRE on native z/OS and z/VM + + +GENERAL + +I (Philip Hazel) have no experience of Windows or VMS sytems and how their +libraries work. The items in the PCRE distribution and Makefile that relate to +anything other than Linux systems are untested by me. + +There are some other comments and files (including some documentation in CHM +format) in the Contrib directory on the FTP site: + + ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/Contrib + +The basic PCRE library consists entirely of code written in Standard C, and so +should compile successfully on any system that has a Standard C compiler and +library. The C++ wrapper functions are a separate issue (see below). + +The PCRE distribution includes a "configure" file for use by the configure/make +(autotools) build system, as found in many Unix-like environments. The README +file contains information about the options for "configure". + +There is also support for CMake, which some users prefer, especially in Windows +environments, though it can also be run in Unix-like environments. See the +section entitled "Building PCRE on Windows with CMake" below. + +Versions of config.h and pcre.h are distributed in the PCRE tarballs under the +names config.h.generic and pcre.h.generic. These are provided for those who +build PCRE without using "configure" or CMake. If you use "configure" or CMake, +the .generic versions are not used. + + +GENERIC INSTRUCTIONS FOR THE PCRE C LIBRARY + +The following are generic instructions for building the PCRE C library "by +hand". If you are going to use CMake, this section does not apply to you; you +can skip ahead to the CMake section. + + (1) Copy or rename the file config.h.generic as config.h, and edit the macro + settings that it contains to whatever is appropriate for your environment. + + In particular, you can alter the definition of the NEWLINE macro to + specify what character(s) you want to be interpreted as line terminators. + In an EBCDIC environment, you MUST change NEWLINE, because its default + value is 10, an ASCII LF. The usual EBCDIC newline character is 21 (0x15, + NL), though in some cases it may be 37 (0x25). + + When you compile any of the PCRE modules, you must specify -DHAVE_CONFIG_H + to your compiler so that config.h is included in the sources. + + An alternative approach is not to edit config.h, but to use -D on the + compiler command line to make any changes that you need to the + configuration options. In this case -DHAVE_CONFIG_H must not be set. + + NOTE: There have been occasions when the way in which certain parameters + in config.h are used has changed between releases. (In the configure/make + world, this is handled automatically.) When upgrading to a new release, + you are strongly advised to review config.h.generic before re-using what + you had previously. + + (2) Copy or rename the file pcre.h.generic as pcre.h. + + (3) EITHER: + Copy or rename file pcre_chartables.c.dist as pcre_chartables.c. + + OR: + Compile dftables.c as a stand-alone program (using -DHAVE_CONFIG_H if + you have set up config.h), and then run it with the single argument + "pcre_chartables.c". This generates a set of standard character tables + and writes them to that file. The tables are generated using the default + C locale for your system. If you want to use a locale that is specified + by LC_xxx environment variables, add the -L option to the dftables + command. You must use this method if you are building on a system that + uses EBCDIC code. + + The tables in pcre_chartables.c are defaults. The caller of PCRE can + specify alternative tables at run time. + + (4) Ensure that you have the following header files: + + pcre_internal.h + ucp.h + + (5) For an 8-bit library, compile the following source files, setting + -DHAVE_CONFIG_H as a compiler option if you have set up config.h with your + configuration, or else use other -D settings to change the configuration + as required. + + pcre_byte_order.c + pcre_chartables.c + pcre_compile.c + pcre_config.c + pcre_dfa_exec.c + pcre_exec.c + pcre_fullinfo.c + pcre_get.c + pcre_globals.c + pcre_jit_compile.c + pcre_maketables.c + pcre_newline.c + pcre_ord2utf8.c + pcre_refcount.c + pcre_string_utils.c + pcre_study.c + pcre_tables.c + pcre_ucd.c + pcre_valid_utf8.c + pcre_version.c + pcre_xclass.c + + Make sure that you include -I. in the compiler command (or equivalent for + an unusual compiler) so that all included PCRE header files are first + sought in the current directory. Otherwise you run the risk of picking up + a previously-installed file from somewhere else. + + Note that you must still compile pcre_jit_compile.c, even if you have not + defined SUPPORT_JIT in config.h, because when JIT support is not + configured, dummy functions are compiled. When JIT support IS configured, + pcre_jit_compile.c #includes sources from the sljit subdirectory, where + there should be 16 files, all of whose names begin with "sljit". + + (6) Now link all the compiled code into an object library in whichever form + your system keeps such libraries. This is the basic PCRE C 8-bit library. + If your system has static and shared libraries, you may have to do this + once for each type. + + (7) If you want to build a 16-bit library (as well as, or instead of the 8-bit + or 32-bit libraries) repeat steps 5-6 with the following files: + + pcre16_byte_order.c + pcre16_chartables.c + pcre16_compile.c + pcre16_config.c + pcre16_dfa_exec.c + pcre16_exec.c + pcre16_fullinfo.c + pcre16_get.c + pcre16_globals.c + pcre16_jit_compile.c + pcre16_maketables.c + pcre16_newline.c + pcre16_ord2utf16.c + pcre16_refcount.c + pcre16_string_utils.c + pcre16_study.c + pcre16_tables.c + pcre16_ucd.c + pcre16_utf16_utils.c + pcre16_valid_utf16.c + pcre16_version.c + pcre16_xclass.c + + (8) If you want to build a 32-bit library (as well as, or instead of the 8-bit + or 16-bit libraries) repeat steps 5-6 with the following files: + + pcre32_byte_order.c + pcre32_chartables.c + pcre32_compile.c + pcre32_config.c + pcre32_dfa_exec.c + pcre32_exec.c + pcre32_fullinfo.c + pcre32_get.c + pcre32_globals.c + pcre32_jit_compile.c + pcre32_maketables.c + pcre32_newline.c + pcre32_ord2utf32.c + pcre32_refcount.c + pcre32_string_utils.c + pcre32_study.c + pcre32_tables.c + pcre32_ucd.c + pcre32_utf32_utils.c + pcre32_valid_utf32.c + pcre32_version.c + pcre32_xclass.c + + (9) If you want to build the POSIX wrapper functions (which apply only to the + 8-bit library), ensure that you have the pcreposix.h file and then compile + pcreposix.c (remembering -DHAVE_CONFIG_H if necessary). Link the result + (on its own) as the pcreposix library. + +(10) The pcretest program can be linked with any combination of the 8-bit, + 16-bit and 32-bit libraries (depending on what you selected in config.h). + Compile pcretest.c and pcre_printint.c (again, don't forget + -DHAVE_CONFIG_H) and link them together with the appropriate library/ies. + If you compiled an 8-bit library, pcretest also needs the pcreposix + wrapper library unless you compiled it with -DNOPOSIX. + +(11) Run pcretest on the testinput files in the testdata directory, and check + that the output matches the corresponding testoutput files. There are + comments about what each test does in the section entitled "Testing PCRE" + in the README file. If you compiled more than one of the 8-bit, 16-bit and + 32-bit libraries, you need to run pcretest with the -16 option to do + 16-bit tests and with the -32 option to do 32-bit tests. + + Some tests are relevant only when certain build-time options are selected. + For example, test 4 is for UTF-8/UTF-16/UTF-32 support, and will not run + if you have built PCRE without it. See the comments at the start of each + testinput file. If you have a suitable Unix-like shell, the RunTest script + will run the appropriate tests for you. The command "RunTest list" will + output a list of all the tests. + + Note that the supplied files are in Unix format, with just LF characters + as line terminators. You may need to edit them to change this if your + system uses a different convention. If you are using Windows, you probably + should use the wintestinput3 file instead of testinput3 (and the + corresponding output file). This is a locale test; wintestinput3 sets the + locale to "french" rather than "fr_FR", and there some minor output + differences. + +(12) If you have built PCRE with SUPPORT_JIT, the JIT features will be tested + by the testdata files. However, you might also like to build and run + the freestanding JIT test program, pcre_jit_test.c. + +(13) If you want to use the pcregrep command, compile and link pcregrep.c; it + uses only the basic 8-bit PCRE library (it does not need the pcreposix + library). + + +THE C++ WRAPPER FUNCTIONS + +The PCRE distribution also contains some C++ wrapper functions and tests, +applicable to the 8-bit library, which were contributed by Google Inc. On a +system that can use "configure" and "make", the functions are automatically +built into a library called pcrecpp. It should be straightforward to compile +the .cc files manually on other systems. The files called xxx_unittest.cc are +test programs for each of the corresponding xxx.cc files. + + +BUILDING FOR VIRTUAL PASCAL + +A script for building PCRE using Borland's C++ compiler for use with VPASCAL +was contributed by Alexander Tokarev. Stefan Weber updated the script and added +additional files. The following files in the distribution are for building PCRE +for use with VP/Borland: makevp_c.txt, makevp_l.txt, makevp.bat, pcregexp.pas. + + +STACK SIZE IN WINDOWS ENVIRONMENTS + +The default processor stack size of 1Mb in some Windows environments is too +small for matching patterns that need much recursion. In particular, test 2 may +fail because of this. Normally, running out of stack causes a crash, but there +have been cases where the test program has just died silently. See your linker +documentation for how to increase stack size if you experience problems. The +Linux default of 8Mb is a reasonable choice for the stack, though even that can +be too small for some pattern/subject combinations. + +PCRE has a compile configuration option to disable the use of stack for +recursion so that heap is used instead. However, pattern matching is +significantly slower when this is done. There is more about stack usage in the +"pcrestack" documentation. + + +LINKING PROGRAMS IN WINDOWS ENVIRONMENTS + +If you want to statically link a program against a PCRE library in the form of +a non-dll .a file, you must define PCRE_STATIC before including pcre.h or +pcrecpp.h, otherwise the pcre_malloc() and pcre_free() exported functions will +be declared __declspec(dllimport), with unwanted results. + + +CALLING CONVENTIONS IN WINDOWS ENVIRONMENTS + +It is possible to compile programs to use different calling conventions using +MSVC. Search the web for "calling conventions" for more information. To make it +easier to change the calling convention for the exported functions in the +PCRE library, the macro PCRE_CALL_CONVENTION is present in all the external +definitions. It can be set externally when compiling (e.g. in CFLAGS). If it is +not set, it defaults to empty; the default calling convention is then used +(which is what is wanted most of the time). + + +COMMENTS ABOUT WIN32 BUILDS (see also "BUILDING PCRE ON WINDOWS WITH CMAKE") + +There are two ways of building PCRE using the "configure, make, make install" +paradigm on Windows systems: using MinGW or using Cygwin. These are not at all +the same thing; they are completely different from each other. There is also +support for building using CMake, which some users find a more straightforward +way of building PCRE under Windows. + +The MinGW home page (http://www.mingw.org/) says this: + + MinGW: A collection of freely available and freely distributable Windows + specific header files and import libraries combined with GNU toolsets that + allow one to produce native Windows programs that do not rely on any + 3rd-party C runtime DLLs. + +The Cygwin home page (http://www.cygwin.com/) says this: + + Cygwin is a Linux-like environment for Windows. It consists of two parts: + + . A DLL (cygwin1.dll) which acts as a Linux API emulation layer providing + substantial Linux API functionality + + . A collection of tools which provide Linux look and feel. + + The Cygwin DLL currently works with all recent, commercially released x86 32 + bit and 64 bit versions of Windows, with the exception of Windows CE. + +On both MinGW and Cygwin, PCRE should build correctly using: + + ./configure && make && make install + +This should create two libraries called libpcre and libpcreposix, and, if you +have enabled building the C++ wrapper, a third one called libpcrecpp. These are +independent libraries: when you link with libpcreposix or libpcrecpp you must +also link with libpcre, which contains the basic functions. (Some earlier +releases of PCRE included the basic libpcre functions in libpcreposix. This no +longer happens.) + +A user submitted a special-purpose patch that makes it easy to create +"pcre.dll" under mingw32 using the "msys" environment. It provides "pcre.dll" +as a special target. If you use this target, no other files are built, and in +particular, the pcretest and pcregrep programs are not built. An example of how +this might be used is: + + ./configure --enable-utf --disable-cpp CFLAGS="-03 -s"; make pcre.dll + +Using Cygwin's compiler generates libraries and executables that depend on +cygwin1.dll. If a library that is generated this way is distributed, +cygwin1.dll has to be distributed as well. Since cygwin1.dll is under the GPL +licence, this forces not only PCRE to be under the GPL, but also the entire +application. A distributor who wants to keep their own code proprietary must +purchase an appropriate Cygwin licence. + +MinGW has no such restrictions. The MinGW compiler generates a library or +executable that can run standalone on Windows without any third party dll or +licensing issues. + +But there is more complication: + +If a Cygwin user uses the -mno-cygwin Cygwin gcc flag, what that really does is +to tell Cygwin's gcc to use the MinGW gcc. Cygwin's gcc is only acting as a +front end to MinGW's gcc (if you install Cygwin's gcc, you get both Cygwin's +gcc and MinGW's gcc). So, a user can: + +. Build native binaries by using MinGW or by getting Cygwin and using + -mno-cygwin. + +. Build binaries that depend on cygwin1.dll by using Cygwin with the normal + compiler flags. + +The test files that are supplied with PCRE are in UNIX format, with LF +characters as line terminators. Unless your PCRE library uses a default newline +option that includes LF as a valid newline, it may be necessary to change the +line terminators in the test files to get some of the tests to work. + + +BUILDING PCRE ON WINDOWS WITH CMAKE + +CMake is an alternative configuration facility that can be used instead of +"configure". CMake creates project files (make files, solution files, etc.) +tailored to numerous development environments, including Visual Studio, +Borland, Msys, MinGW, NMake, and Unix. If possible, use short paths with no +spaces in the names for your CMake installation and your PCRE source and build +directories. + +The following instructions were contributed by a PCRE user. If they are not +followed exactly, errors may occur. In the event that errors do occur, it is +recommended that you delete the CMake cache before attempting to repeat the +CMake build process. In the CMake GUI, the cache can be deleted by selecting +"File > Delete Cache". + +1. Install the latest CMake version available from http://www.cmake.org/, and + ensure that cmake\bin is on your path. + +2. Unzip (retaining folder structure) the PCRE source tree into a source + directory such as C:\pcre. You should ensure your local date and time + is not earlier than the file dates in your source dir if the release is + very new. + +3. Create a new, empty build directory, preferably a subdirectory of the + source dir. For example, C:\pcre\pcre-xx\build. + +4. Run cmake-gui from the Shell envirornment of your build tool, for example, + Msys for Msys/MinGW or Visual Studio Command Prompt for VC/VC++. Do not try + to start Cmake from the Windows Start menu, as this can lead to errors. + +5. Enter C:\pcre\pcre-xx and C:\pcre\pcre-xx\build for the source and build + directories, respectively. + +6. Hit the "Configure" button. + +7. Select the particular IDE / build tool that you are using (Visual + Studio, MSYS makefiles, MinGW makefiles, etc.) + +8. The GUI will then list several configuration options. This is where + you can enable UTF-8 support or other PCRE optional features. + +9. Hit "Configure" again. The adjacent "Generate" button should now be + active. + +10. Hit "Generate". + +11. The build directory should now contain a usable build system, be it a + solution file for Visual Studio, makefiles for MinGW, etc. Exit from + cmake-gui and use the generated build system with your compiler or IDE. + E.g., for MinGW you can run "make", or for Visual Studio, open the PCRE + solution, select the desired configuration (Debug, or Release, etc.) and + build the ALL_BUILD project. + +12. If during configuration with cmake-gui you've elected to build the test + programs, you can execute them by building the test project. E.g., for + MinGW: "make test"; for Visual Studio build the RUN_TESTS project. The + most recent build configuration is targeted by the tests. A summary of + test results is presented. Complete test output is subsequently + available for review in Testing\Temporary under your build dir. + + +USE OF RELATIVE PATHS WITH CMAKE ON WINDOWS + +A PCRE user comments as follows: I thought that others may want to know the +current state of CMAKE_USE_RELATIVE_PATHS support on Windows. Here it is: + +-- AdditionalIncludeDirectories is only partially modified (only the + first path - see below) +-- Only some of the contained file paths are modified - shown below for + pcre.vcproj +-- It properly modifies + +I am sure CMake people can fix that if they want to. Until then one will +need to replace existing absolute paths in project files with relative +paths manually (e.g. from VS) - relative to project file location. I did +just that before being told to try CMAKE_USE_RELATIVE_PATHS. Not a big +deal. + +AdditionalIncludeDirectories="E:\builds\pcre\build;E:\builds\pcre\pcre-7.5;" +AdditionalIncludeDirectories=".;E:\builds\pcre\pcre-7.5;" + +RelativePath="pcre.h" +RelativePath="pcre_chartables.c" +RelativePath="pcre_chartables.c.rule" + + +TESTING WITH RUNTEST.BAT + +If configured with CMake, building the test project ("make test" or building +ALL_TESTS in Visual Studio) creates (and runs) pcre_test.bat (and depending +on your configuration options, possibly other test programs) in the build +directory. Pcre_test.bat runs RunTest.Bat with correct source and exe paths. + +For manual testing with RunTest.bat, provided the build dir is a subdirectory +of the source directory: Open command shell window. Chdir to the location +of your pcretest.exe and pcregrep.exe programs. Call RunTest.bat with +"..\RunTest.Bat" or "..\..\RunTest.bat" as appropriate. + +To run only a particular test with RunTest.Bat provide a test number argument. + +Otherwise: + +1. Copy RunTest.bat into the directory where pcretest.exe and pcregrep.exe + have been created. + +2. Edit RunTest.bat to indentify the full or relative location of + the pcre source (wherein which the testdata folder resides), e.g.: + + set srcdir=C:\pcre\pcre-8.20 + +3. In a Windows command environment, chdir to the location of your bat and + exe programs. + +4. Run RunTest.bat. Test outputs will automatically be compared to expected + results, and discrepancies will be identified in the console output. + +To independently test the just-in-time compiler, run pcre_jit_test.exe. +To test pcrecpp, run pcrecpp_unittest.exe, pcre_stringpiece_unittest.exe and +pcre_scanner_unittest.exe. + + +BUILDING UNDER WINDOWS CE WITH VISUAL STUDIO 200x + +Vincent Richomme sent a zip archive of files to help with this process. They +can be found in the file "pcre-vsbuild.zip" in the Contrib directory of the FTP +site. + + +BUILDING UNDER WINDOWS WITH BCC5.5 + +Michael Roy sent these comments about building PCRE under Windows with BCC5.5: + +Some of the core BCC libraries have a version of PCRE from 1998 built in, which +can lead to pcre_exec() giving an erroneous PCRE_ERROR_NULL from a version +mismatch. I'm including an easy workaround below, if you'd like to include it +in the non-unix instructions: + +When linking a project with BCC5.5, pcre.lib must be included before any of the +libraries cw32.lib, cw32i.lib, cw32mt.lib, and cw32mti.lib on the command line. + + +BUILDING USING BORLAND C++ BUILDER 2007 (CB2007) AND HIGHER + +A PCRE user sent these comments about this environment (see also the comment +from another user that follows them): + +The XE versions of C++ Builder come with a RegularExpressionsCore class which +contain a version of TPerlRegEx. However, direct use of the C PCRE library may +be desirable. + +The default makevp.bat, however, supplied with PCRE builds a version of PCRE +that is not usable with any version of C++ Builder because the compiler ships +with an embedded version of PCRE, version 2.01 from 1998! [See also the note +about BCC5.5 above.] If you want to use PCRE you'll need to rename the +functions (pcre_compile to pcre_compile_bcc, etc) or do as I have done and just +use the 16 bit versions. I'm using std::wstring everywhere anyway. Since the +embedded version of PCRE does not have the 16 bit function names, there is no +conflict. + +Building PCRE using a C++ Builder static library project file (recommended): + +1. Rename or remove pcre.h, pcreposi.h, and pcreposix.h from your C++ Builder +original include path. + +2. Download PCRE from pcre.org and extract to a directory. + +3. Rename pcre_chartables.c.dist to pcre_chartables.c, pcre.h.generic to +pcre.h, and config.h.generic to config.h. + +4. Edit pcre.h and pcre_config.c so that they include config.h. + +5. Edit config.h like so: + +Comment out the following lines: +#define PACKAGE "pcre" +#define PACKAGE_BUGREPORT "" +#define PACKAGE_NAME "PCRE" +#define PACKAGE_STRING "PCRE 8.32" +#define PACKAGE_TARNAME "pcre" +#define PACKAGE_URL "" +#define PACKAGE_VERSION "8.32" + +Add the following lines: +#ifndef SUPPORT_UTF +#define SUPPORT_UTF 100 // any value is fine +#endif + +#ifndef SUPPORT_UCP +#define SUPPORT_UCP 101 // any value is fine +#endif + +#ifndef SUPPORT_UCP +#define SUPPORT_PCRE16 102 // any value is fine +#endif + +#ifndef SUPPORT_UTF8 +#define SUPPORT_UTF8 103 // any value is fine +#endif + +6. Build a C++ Builder project using the IDE. Go to File / New / Other and +choose Static Library. You can name it pcre.cbproj or whatever. Now set your +paths by going to Project / Options. Set the Include path. Do this from the +"Base" option to apply to both Release and Debug builds. Now add the following +files to the project: + +pcre.h +pcre16_byte_order.c +pcre16_chartables.c +pcre16_compile.c +pcre16_config.c +pcre16_dfa_exec.c +pcre16_exec.c +pcre16_fullinfo.c +pcre16_get.c +pcre16_globals.c +pcre16_maketables.c +pcre16_newline.c +pcre16_ord2utf16.c +pcre16_printint.c +pcre16_refcount.c +pcre16_string_utils.c +pcre16_study.c +pcre16_tables.c +pcre16_ucd.c +pcre16_utf16_utils.c +pcre16_valid_utf16.c +pcre16_version.c +pcre16_xclass.c + +//Optional +pcre_version.c + +7. After compiling the .lib file, copy the .lib and header files to a project +you want to use PCRE with. Enjoy. + +Optional ... Building PCRE using the makevp.bat file: + +1. Edit makevp_c.txt and makevp_l.txt and change all the names to the 16 bit +versions. + +2. Edit makevp.bat and set the path to C++ Builder. Run makevp.bat. + +Another PCRE user added this comment: + +Another approach I successfully used for some years with BCB 5 and 6 was to +make sure that include and library paths of PCRE are configured before the +default paths of the IDE in the dialogs where one can manage those paths. +Afterwards one can open the project files using a text editor and manually add +the self created library for pcre itself, pcrecpp doesn't ship with the IDE, in +the library nodes where the IDE manages its own libraries to link against in +front of the IDE-own libraries. This way one can use the default PCRE function +names without getting access violations on runtime. + + + + +BUILDING PCRE ON OPENVMS + +Stephen Hoffman sent the following, in December 2012: + +"Here is a very short write-up on the +OpenVMS port and here + + + +is a zip with the OpenVMS files, and with one modified testing-related PCRE +file." This is a port of PCRE 8.32. + +Earlier, Dan Mooney sent the following comments about building PCRE on OpenVMS. +They relate to an older version of PCRE that used fewer source files, so the +exact commands will need changing. See the current list of source files above. + +"It was quite easy to compile and link the library. I don't have a formal +make file but the attached file [reproduced below] contains the OpenVMS DCL +commands I used to build the library. I had to add #define +POSIX_MALLOC_THRESHOLD 10 to pcre.h since it was not defined anywhere. + +The library was built on: +O/S: HP OpenVMS v7.3-1 +Compiler: Compaq C v6.5-001-48BCD +Linker: vA13-01 + +The test results did not match 100% due to the issues you mention in your +documentation regarding isprint(), iscntrl(), isgraph() and ispunct(). I +modified some of the character tables temporarily and was able to get the +results to match. Tests using the fr locale did not match since I don't have +that locale loaded. The study size was always reported to be 3 less than the +value in the standard test output files." + +========================= +$! This DCL procedure builds PCRE on OpenVMS +$! +$! I followed the instructions in the non-unix-use file in the distribution. +$! +$ COMPILE == "CC/LIST/NOMEMBER_ALIGNMENT/PREFIX_LIBRARY_ENTRIES=ALL_ENTRIES +$ COMPILE DFTABLES.C +$ LINK/EXE=DFTABLES.EXE DFTABLES.OBJ +$ RUN DFTABLES.EXE/OUTPUT=CHARTABLES.C +$ COMPILE MAKETABLES.C +$ COMPILE GET.C +$ COMPILE STUDY.C +$! I had to set POSIX_MALLOC_THRESHOLD to 10 in PCRE.H since the symbol +$! did not seem to be defined anywhere. +$! I edited pcre.h and added #DEFINE SUPPORT_UTF8 to enable UTF8 support. +$ COMPILE PCRE.C +$ LIB/CREATE PCRE MAKETABLES.OBJ, GET.OBJ, STUDY.OBJ, PCRE.OBJ +$! I had to set POSIX_MALLOC_THRESHOLD to 10 in PCRE.H since the symbol +$! did not seem to be defined anywhere. +$ COMPILE PCREPOSIX.C +$ LIB/CREATE PCREPOSIX PCREPOSIX.OBJ +$ COMPILE PCRETEST.C +$ LINK/EXE=PCRETEST.EXE PCRETEST.OBJ, PCRE/LIB, PCREPOSIX/LIB +$! C programs that want access to command line arguments must be +$! defined as a symbol +$ PCRETEST :== "$ SYS$ROADSUSERS:[DMOONEY.REGEXP]PCRETEST.EXE" +$! Arguments must be enclosed in quotes. +$ PCRETEST "-C" +$! Test results: +$! +$! The test results did not match 100%. The functions isprint(), iscntrl(), +$! isgraph() and ispunct() on OpenVMS must not produce the same results +$! as the system that built the test output files provided with the +$! distribution. +$! +$! The study size did not match and was always 3 less on OpenVMS. +$! +$! Locale could not be set to fr +$! +========================= + + +BUILDING PCRE ON STRATUS OPENVOS + +These notes on the port of PCRE to VOS (lightly edited) were supplied by +Ashutosh Warikoo, whose email address has the local part awarikoo and the +domain nse.co.in. The port was for version 7.9 in August 2009. + +1. Building PCRE + +I built pcre on OpenVOS Release 17.0.1at using GNU Tools 3.4a without any +problems. I used the following packages to build PCRE: + + ftp://ftp.stratus.com/pub/vos/posix/ga/posix.save.evf.gz + +Please read and follow the instructions that come with these packages. To start +the build of pcre, from the root of the package type: + + ./build.sh + +2. Installing PCRE + +Once you have successfully built PCRE, login to the SysAdmin group, switch to +the root user, and type + + [ !create_dir (master_disk)>usr --if needed ] + [ !create_dir (master_disk)>usr>local --if needed ] + !gmake install + +This installs PCRE and its man pages into /usr/local. You can add +(master_disk)>usr>local>bin to your command search paths, or if you are in +BASH, add /usr/local/bin to the PATH environment variable. + +4. Restrictions + +This port requires readline library optionally. However during the build I +faced some yet unexplored errors while linking with readline. As it was an +optional component I chose to disable it. + +5. Known Problems + +I ran the test suite, but you will have to be your own judge of whether this +command, and this port, suits your purposes. If you find any problems that +appear to be related to the port itself, please let me know. Please see the +build.log file in the root of the package also. + + +BUILDING PCRE ON NATIVE Z/OS AND Z/VM + +z/OS and z/VM are operating systems for mainframe computers, produced by IBM. +The character code used is EBCDIC, not ASCII or Unicode. In z/OS, UNIX APIs and +applications can be supported through UNIX System Services, and in such an +environment PCRE can be built in the same way as in other systems. However, in +native z/OS (without UNIX System Services) and in z/VM, special ports are +required. For details, please see this web site: + + http://www.zaconsultants.net + +There is also a mirror here: + + http://www.vsoft-software.com/downloads.html + +========================== +Last Updated: 14 May 2013 diff --git a/doc/html/README.txt b/doc/html/README.txt new file mode 100644 index 0000000..88f2dfd --- /dev/null +++ b/doc/html/README.txt @@ -0,0 +1,991 @@ +README file for PCRE (Perl-compatible regular expression library) +----------------------------------------------------------------- + +The latest release of PCRE is always available in three alternative formats +from: + + ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.tar.gz + ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.tar.bz2 + ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.zip + +There is a mailing list for discussion about the development of PCRE at +pcre-dev@exim.org. You can access the archives and subscribe or manage your +subscription here: + + https://lists.exim.org/mailman/listinfo/pcre-dev + +Please read the NEWS file if you are upgrading from a previous release. +The contents of this README file are: + + The PCRE APIs + Documentation for PCRE + Contributions by users of PCRE + Building PCRE on non-Unix-like systems + Building PCRE without using autotools + Building PCRE using autotools + Retrieving configuration information + Shared libraries + Cross-compiling using autotools + Using HP's ANSI C++ compiler (aCC) + Compiling in Tru64 using native compilers + Using Sun's compilers for Solaris + Using PCRE from MySQL + Making new tarballs + Testing PCRE + Character tables + File manifest + + +The PCRE APIs +------------- + +PCRE is written in C, and it has its own API. There are three sets of +functions, one for the 8-bit library, which processes strings of bytes, one for +the 16-bit library, which processes strings of 16-bit values, and one for the +32-bit library, which processes strings of 32-bit values. The distribution also +includes a set of C++ wrapper functions (see the pcrecpp man page for details), +courtesy of Google Inc., which can be used to call the 8-bit PCRE library from +C++. + +In addition, there is a set of C wrapper functions (again, just for the 8-bit +library) that are based on the POSIX regular expression API (see the pcreposix +man page). These end up in the library called libpcreposix. Note that this just +provides a POSIX calling interface to PCRE; the regular expressions themselves +still follow Perl syntax and semantics. The POSIX API is restricted, and does +not give full access to all of PCRE's facilities. + +The header file for the POSIX-style functions is called pcreposix.h. The +official POSIX name is regex.h, but I did not want to risk possible problems +with existing files of that name by distributing it that way. To use PCRE with +an existing program that uses the POSIX API, pcreposix.h will have to be +renamed or pointed at by a link. + +If you are using the POSIX interface to PCRE and there is already a POSIX regex +library installed on your system, as well as worrying about the regex.h header +file (as mentioned above), you must also take care when linking programs to +ensure that they link with PCRE's libpcreposix library. Otherwise they may pick +up the POSIX functions of the same name from the other library. + +One way of avoiding this confusion is to compile PCRE with the addition of +-Dregcomp=PCREregcomp (and similarly for the other POSIX functions) to the +compiler flags (CFLAGS if you are using "configure" -- see below). This has the +effect of renaming the functions so that the names no longer clash. Of course, +you have to do the same thing for your applications, or write them using the +new names. + + +Documentation for PCRE +---------------------- + +If you install PCRE in the normal way on a Unix-like system, you will end up +with a set of man pages whose names all start with "pcre". The one that is just +called "pcre" lists all the others. In addition to these man pages, the PCRE +documentation is supplied in two other forms: + + 1. There are files called doc/pcre.txt, doc/pcregrep.txt, and + doc/pcretest.txt in the source distribution. The first of these is a + concatenation of the text forms of all the section 3 man pages except + the listing of pcredemo.c and those that summarize individual functions. + The other two are the text forms of the section 1 man pages for the + pcregrep and pcretest commands. These text forms are provided for ease of + scanning with text editors or similar tools. They are installed in + /share/doc/pcre, where is the installation prefix + (defaulting to /usr/local). + + 2. A set of files containing all the documentation in HTML form, hyperlinked + in various ways, and rooted in a file called index.html, is distributed in + doc/html and installed in /share/doc/pcre/html. + +Users of PCRE have contributed files containing the documentation for various +releases in CHM format. These can be found in the Contrib directory of the FTP +site (see next section). + + +Contributions by users of PCRE +------------------------------ + +You can find contributions from PCRE users in the directory + + ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/Contrib + +There is a README file giving brief descriptions of what they are. Some are +complete in themselves; others are pointers to URLs containing relevant files. +Some of this material is likely to be well out-of-date. Several of the earlier +contributions provided support for compiling PCRE on various flavours of +Windows (I myself do not use Windows). Nowadays there is more Windows support +in the standard distribution, so these contibutions have been archived. + +A PCRE user maintains downloadable Windows binaries of the pcregrep and +pcretest programs here: + + http://www.rexegg.com/pcregrep-pcretest.html + + +Building PCRE on non-Unix-like systems +-------------------------------------- + +For a non-Unix-like system, please read the comments in the file +NON-AUTOTOOLS-BUILD, though if your system supports the use of "configure" and +"make" you may be able to build PCRE using autotools in the same way as for +many Unix-like systems. + +PCRE can also be configured using the GUI facility provided by CMake's +cmake-gui command. This creates Makefiles, solution files, etc. The file +NON-AUTOTOOLS-BUILD has information about CMake. + +PCRE has been compiled on many different operating systems. It should be +straightforward to build PCRE on any system that has a Standard C compiler and +library, because it uses only Standard C functions. + + +Building PCRE without using autotools +------------------------------------- + +The use of autotools (in particular, libtool) is problematic in some +environments, even some that are Unix or Unix-like. See the NON-AUTOTOOLS-BUILD +file for ways of building PCRE without using autotools. + + +Building PCRE using autotools +----------------------------- + +If you are using HP's ANSI C++ compiler (aCC), please see the special note +in the section entitled "Using HP's ANSI C++ compiler (aCC)" below. + +The following instructions assume the use of the widely used "configure; make; +make install" (autotools) process. + +To build PCRE on system that supports autotools, first run the "configure" +command from the PCRE distribution directory, with your current directory set +to the directory where you want the files to be created. This command is a +standard GNU "autoconf" configuration script, for which generic instructions +are supplied in the file INSTALL. + +Most commonly, people build PCRE within its own distribution directory, and in +this case, on many systems, just running "./configure" is sufficient. However, +the usual methods of changing standard defaults are available. For example: + +CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local + +This command specifies that the C compiler should be run with the flags '-O2 +-Wall' instead of the default, and that "make install" should install PCRE +under /opt/local instead of the default /usr/local. + +If you want to build in a different directory, just run "configure" with that +directory as current. For example, suppose you have unpacked the PCRE source +into /source/pcre/pcre-xxx, but you want to build it in /build/pcre/pcre-xxx: + +cd /build/pcre/pcre-xxx +/source/pcre/pcre-xxx/configure + +PCRE is written in C and is normally compiled as a C library. However, it is +possible to build it as a C++ library, though the provided building apparatus +does not have any features to support this. + +There are some optional features that can be included or omitted from the PCRE +library. They are also documented in the pcrebuild man page. + +. By default, both shared and static libraries are built. You can change this + by adding one of these options to the "configure" command: + + --disable-shared + --disable-static + + (See also "Shared libraries on Unix-like systems" below.) + +. By default, only the 8-bit library is built. If you add --enable-pcre16 to + the "configure" command, the 16-bit library is also built. If you add + --enable-pcre32 to the "configure" command, the 32-bit library is also built. + If you want only the 16-bit or 32-bit library, use --disable-pcre8 to disable + building the 8-bit library. + +. If you are building the 8-bit library and want to suppress the building of + the C++ wrapper library, you can add --disable-cpp to the "configure" + command. Otherwise, when "configure" is run without --disable-pcre8, it will + try to find a C++ compiler and C++ header files, and if it succeeds, it will + try to build the C++ wrapper. + +. If you want to include support for just-in-time compiling, which can give + large performance improvements on certain platforms, add --enable-jit to the + "configure" command. This support is available only for certain hardware + architectures. If you try to enable it on an unsupported architecture, there + will be a compile time error. + +. When JIT support is enabled, pcregrep automatically makes use of it, unless + you add --disable-pcregrep-jit to the "configure" command. + +. If you want to make use of the support for UTF-8 Unicode character strings in + the 8-bit library, or UTF-16 Unicode character strings in the 16-bit library, + or UTF-32 Unicode character strings in the 32-bit library, you must add + --enable-utf to the "configure" command. Without it, the code for handling + UTF-8, UTF-16 and UTF-8 is not included in the relevant library. Even + when --enable-utf is included, the use of a UTF encoding still has to be + enabled by an option at run time. When PCRE is compiled with this option, its + input can only either be ASCII or UTF-8/16/32, even when running on EBCDIC + platforms. It is not possible to use both --enable-utf and --enable-ebcdic at + the same time. + +. There are no separate options for enabling UTF-8, UTF-16 and UTF-32 + independently because that would allow ridiculous settings such as requesting + UTF-16 support while building only the 8-bit library. However, the option + --enable-utf8 is retained for backwards compatibility with earlier releases + that did not support 16-bit or 32-bit character strings. It is synonymous with + --enable-utf. It is not possible to configure one library with UTF support + and the other without in the same configuration. + +. If, in addition to support for UTF-8/16/32 character strings, you want to + include support for the \P, \p, and \X sequences that recognize Unicode + character properties, you must add --enable-unicode-properties to the + "configure" command. This adds about 30K to the size of the library (in the + form of a property table); only the basic two-letter properties such as Lu + are supported. + +. You can build PCRE to recognize either CR or LF or the sequence CRLF or any + of the preceding, or any of the Unicode newline sequences as indicating the + end of a line. Whatever you specify at build time is the default; the caller + of PCRE can change the selection at run time. The default newline indicator + is a single LF character (the Unix standard). You can specify the default + newline indicator by adding --enable-newline-is-cr or --enable-newline-is-lf + or --enable-newline-is-crlf or --enable-newline-is-anycrlf or + --enable-newline-is-any to the "configure" command, respectively. + + If you specify --enable-newline-is-cr or --enable-newline-is-crlf, some of + the standard tests will fail, because the lines in the test files end with + LF. Even if the files are edited to change the line endings, there are likely + to be some failures. With --enable-newline-is-anycrlf or + --enable-newline-is-any, many tests should succeed, but there may be some + failures. + +. By default, the sequence \R in a pattern matches any Unicode line ending + sequence. This is independent of the option specifying what PCRE considers to + be the end of a line (see above). However, the caller of PCRE can restrict \R + to match only CR, LF, or CRLF. You can make this the default by adding + --enable-bsr-anycrlf to the "configure" command (bsr = "backslash R"). + +. When called via the POSIX interface, PCRE uses malloc() to get additional + storage for processing capturing parentheses if there are more than 10 of + them in a pattern. You can increase this threshold by setting, for example, + + --with-posix-malloc-threshold=20 + + on the "configure" command. + +. PCRE has a counter that limits the depth of nesting of parentheses in a + pattern. This limits the amount of system stack that a pattern uses when it + is compiled. The default is 250, but you can change it by setting, for + example, + + --with-parens-nest-limit=500 + +. PCRE has a counter that can be set to limit the amount of resources it uses + when matching a pattern. If the limit is exceeded during a match, the match + fails. The default is ten million. You can change the default by setting, for + example, + + --with-match-limit=500000 + + on the "configure" command. This is just the default; individual calls to + pcre_exec() can supply their own value. There is more discussion on the + pcreapi man page. + +. There is a separate counter that limits the depth of recursive function calls + during a matching process. This also has a default of ten million, which is + essentially "unlimited". You can change the default by setting, for example, + + --with-match-limit-recursion=500000 + + Recursive function calls use up the runtime stack; running out of stack can + cause programs to crash in strange ways. There is a discussion about stack + sizes in the pcrestack man page. + +. The default maximum compiled pattern size is around 64K. You can increase + this by adding --with-link-size=3 to the "configure" command. In the 8-bit + library, PCRE then uses three bytes instead of two for offsets to different + parts of the compiled pattern. In the 16-bit library, --with-link-size=3 is + the same as --with-link-size=4, which (in both libraries) uses four-byte + offsets. Increasing the internal link size reduces performance. In the 32-bit + library, the only supported link size is 4. + +. You can build PCRE so that its internal match() function that is called from + pcre_exec() does not call itself recursively. Instead, it uses memory blocks + obtained from the heap via the special functions pcre_stack_malloc() and + pcre_stack_free() to save data that would otherwise be saved on the stack. To + build PCRE like this, use + + --disable-stack-for-recursion + + on the "configure" command. PCRE runs more slowly in this mode, but it may be + necessary in environments with limited stack sizes. This applies only to the + normal execution of the pcre_exec() function; if JIT support is being + successfully used, it is not relevant. Equally, it does not apply to + pcre_dfa_exec(), which does not use deeply nested recursion. There is a + discussion about stack sizes in the pcrestack man page. + +. For speed, PCRE uses four tables for manipulating and identifying characters + whose code point values are less than 256. By default, it uses a set of + tables for ASCII encoding that is part of the distribution. If you specify + + --enable-rebuild-chartables + + a program called dftables is compiled and run in the default C locale when + you obey "make". It builds a source file called pcre_chartables.c. If you do + not specify this option, pcre_chartables.c is created as a copy of + pcre_chartables.c.dist. See "Character tables" below for further information. + +. It is possible to compile PCRE for use on systems that use EBCDIC as their + character code (as opposed to ASCII/Unicode) by specifying + + --enable-ebcdic + + This automatically implies --enable-rebuild-chartables (see above). However, + when PCRE is built this way, it always operates in EBCDIC. It cannot support + both EBCDIC and UTF-8/16/32. There is a second option, --enable-ebcdic-nl25, + which specifies that the code value for the EBCDIC NL character is 0x25 + instead of the default 0x15. + +. In environments where valgrind is installed, if you specify + + --enable-valgrind + + PCRE will use valgrind annotations to mark certain memory regions as + unaddressable. This allows it to detect invalid memory accesses, and is + mostly useful for debugging PCRE itself. + +. In environments where the gcc compiler is used and lcov version 1.6 or above + is installed, if you specify + + --enable-coverage + + the build process implements a code coverage report for the test suite. The + report is generated by running "make coverage". If ccache is installed on + your system, it must be disabled when building PCRE for coverage reporting. + You can do this by setting the environment variable CCACHE_DISABLE=1 before + running "make" to build PCRE. There is more information about coverage + reporting in the "pcrebuild" documentation. + +. The pcregrep program currently supports only 8-bit data files, and so + requires the 8-bit PCRE library. It is possible to compile pcregrep to use + libz and/or libbz2, in order to read .gz and .bz2 files (respectively), by + specifying one or both of + + --enable-pcregrep-libz + --enable-pcregrep-libbz2 + + Of course, the relevant libraries must be installed on your system. + +. The default size (in bytes) of the internal buffer used by pcregrep can be + set by, for example: + + --with-pcregrep-bufsize=51200 + + The value must be a plain integer. The default is 20480. + +. It is possible to compile pcretest so that it links with the libreadline + or libedit libraries, by specifying, respectively, + + --enable-pcretest-libreadline or --enable-pcretest-libedit + + If this is done, when pcretest's input is from a terminal, it reads it using + the readline() function. This provides line-editing and history facilities. + Note that libreadline is GPL-licenced, so if you distribute a binary of + pcretest linked in this way, there may be licensing issues. These can be + avoided by linking with libedit (which has a BSD licence) instead. + + Enabling libreadline causes the -lreadline option to be added to the pcretest + build. In many operating environments with a sytem-installed readline + library this is sufficient. However, in some environments (e.g. if an + unmodified distribution version of readline is in use), it may be necessary + to specify something like LIBS="-lncurses" as well. This is because, to quote + the readline INSTALL, "Readline uses the termcap functions, but does not link + with the termcap or curses library itself, allowing applications which link + with readline the to choose an appropriate library." If you get error + messages about missing functions tgetstr, tgetent, tputs, tgetflag, or tgoto, + this is the problem, and linking with the ncurses library should fix it. + +The "configure" script builds the following files for the basic C library: + +. Makefile the makefile that builds the library +. config.h build-time configuration options for the library +. pcre.h the public PCRE header file +. pcre-config script that shows the building settings such as CFLAGS + that were set for "configure" +. libpcre.pc ) data for the pkg-config command +. libpcre16.pc ) +. libpcre32.pc ) +. libpcreposix.pc ) +. libtool script that builds shared and/or static libraries + +Versions of config.h and pcre.h are distributed in the PCRE tarballs under the +names config.h.generic and pcre.h.generic. These are provided for those who +have to built PCRE without using "configure" or CMake. If you use "configure" +or CMake, the .generic versions are not used. + +When building the 8-bit library, if a C++ compiler is found, the following +files are also built: + +. libpcrecpp.pc data for the pkg-config command +. pcrecpparg.h header file for calling PCRE via the C++ wrapper +. pcre_stringpiece.h header for the C++ "stringpiece" functions + +The "configure" script also creates config.status, which is an executable +script that can be run to recreate the configuration, and config.log, which +contains compiler output from tests that "configure" runs. + +Once "configure" has run, you can run "make". This builds the the libraries +libpcre, libpcre16 and/or libpcre32, and a test program called pcretest. If you +enabled JIT support with --enable-jit, a test program called pcre_jit_test is +built as well. + +If the 8-bit library is built, libpcreposix and the pcregrep command are also +built, and if a C++ compiler was found on your system, and you did not disable +it with --disable-cpp, "make" builds the C++ wrapper library, which is called +libpcrecpp, as well as some test programs called pcrecpp_unittest, +pcre_scanner_unittest, and pcre_stringpiece_unittest. + +The command "make check" runs all the appropriate tests. Details of the PCRE +tests are given below in a separate section of this document. + +You can use "make install" to install PCRE into live directories on your +system. The following are installed (file names are all relative to the + that is set when "configure" is run): + + Commands (bin): + pcretest + pcregrep (if 8-bit support is enabled) + pcre-config + + Libraries (lib): + libpcre16 (if 16-bit support is enabled) + libpcre32 (if 32-bit support is enabled) + libpcre (if 8-bit support is enabled) + libpcreposix (if 8-bit support is enabled) + libpcrecpp (if 8-bit and C++ support is enabled) + + Configuration information (lib/pkgconfig): + libpcre16.pc + libpcre32.pc + libpcre.pc + libpcreposix.pc + libpcrecpp.pc (if C++ support is enabled) + + Header files (include): + pcre.h + pcreposix.h + pcre_scanner.h ) + pcre_stringpiece.h ) if C++ support is enabled + pcrecpp.h ) + pcrecpparg.h ) + + Man pages (share/man/man{1,3}): + pcregrep.1 + pcretest.1 + pcre-config.1 + pcre.3 + pcre*.3 (lots more pages, all starting "pcre") + + HTML documentation (share/doc/pcre/html): + index.html + *.html (lots more pages, hyperlinked from index.html) + + Text file documentation (share/doc/pcre): + AUTHORS + COPYING + ChangeLog + LICENCE + NEWS + README + pcre.txt (a concatenation of the man(3) pages) + pcretest.txt the pcretest man page + pcregrep.txt the pcregrep man page + pcre-config.txt the pcre-config man page + +If you want to remove PCRE from your system, you can run "make uninstall". +This removes all the files that "make install" installed. However, it does not +remove any directories, because these are often shared with other programs. + + +Retrieving configuration information +------------------------------------ + +Running "make install" installs the command pcre-config, which can be used to +recall information about the PCRE configuration and installation. For example: + + pcre-config --version + +prints the version number, and + + pcre-config --libs + +outputs information about where the library is installed. This command can be +included in makefiles for programs that use PCRE, saving the programmer from +having to remember too many details. + +The pkg-config command is another system for saving and retrieving information +about installed libraries. Instead of separate commands for each library, a +single command is used. For example: + + pkg-config --cflags pcre + +The data is held in *.pc files that are installed in a directory called +/lib/pkgconfig. + + +Shared libraries +---------------- + +The default distribution builds PCRE as shared libraries and static libraries, +as long as the operating system supports shared libraries. Shared library +support relies on the "libtool" script which is built as part of the +"configure" process. + +The libtool script is used to compile and link both shared and static +libraries. They are placed in a subdirectory called .libs when they are newly +built. The programs pcretest and pcregrep are built to use these uninstalled +libraries (by means of wrapper scripts in the case of shared libraries). When +you use "make install" to install shared libraries, pcregrep and pcretest are +automatically re-built to use the newly installed shared libraries before being +installed themselves. However, the versions left in the build directory still +use the uninstalled libraries. + +To build PCRE using static libraries only you must use --disable-shared when +configuring it. For example: + +./configure --prefix=/usr/gnu --disable-shared + +Then run "make" in the usual way. Similarly, you can use --disable-static to +build only shared libraries. + + +Cross-compiling using autotools +------------------------------- + +You can specify CC and CFLAGS in the normal way to the "configure" command, in +order to cross-compile PCRE for some other host. However, you should NOT +specify --enable-rebuild-chartables, because if you do, the dftables.c source +file is compiled and run on the local host, in order to generate the inbuilt +character tables (the pcre_chartables.c file). This will probably not work, +because dftables.c needs to be compiled with the local compiler, not the cross +compiler. + +When --enable-rebuild-chartables is not specified, pcre_chartables.c is created +by making a copy of pcre_chartables.c.dist, which is a default set of tables +that assumes ASCII code. Cross-compiling with the default tables should not be +a problem. + +If you need to modify the character tables when cross-compiling, you should +move pcre_chartables.c.dist out of the way, then compile dftables.c by hand and +run it on the local host to make a new version of pcre_chartables.c.dist. +Then when you cross-compile PCRE this new version of the tables will be used. + + +Using HP's ANSI C++ compiler (aCC) +---------------------------------- + +Unless C++ support is disabled by specifying the "--disable-cpp" option of the +"configure" script, you must include the "-AA" option in the CXXFLAGS +environment variable in order for the C++ components to compile correctly. + +Also, note that the aCC compiler on PA-RISC platforms may have a defect whereby +needed libraries fail to get included when specifying the "-AA" compiler +option. If you experience unresolved symbols when linking the C++ programs, +use the workaround of specifying the following environment variable prior to +running the "configure" script: + + CXXLDFLAGS="-lstd_v2 -lCsup_v2" + + +Compiling in Tru64 using native compilers +----------------------------------------- + +The following error may occur when compiling with native compilers in the Tru64 +operating system: + + CXX libpcrecpp_la-pcrecpp.lo +cxx: Error: /usr/lib/cmplrs/cxx/V7.1-006/include/cxx/iosfwd, line 58: #error + directive: "cannot include iosfwd -- define __USE_STD_IOSTREAM to + override default - see section 7.1.2 of the C++ Using Guide" +#error "cannot include iosfwd -- define __USE_STD_IOSTREAM to override default +- see section 7.1.2 of the C++ Using Guide" + +This may be followed by other errors, complaining that 'namespace "std" has no +member'. The solution to this is to add the line + +#define __USE_STD_IOSTREAM 1 + +to the config.h file. + + +Using Sun's compilers for Solaris +--------------------------------- + +A user reports that the following configurations work on Solaris 9 sparcv9 and +Solaris 9 x86 (32-bit): + + Solaris 9 sparcv9: ./configure --disable-cpp CC=/bin/cc CFLAGS="-m64 -g" + Solaris 9 x86: ./configure --disable-cpp CC=/bin/cc CFLAGS="-g" + + +Using PCRE from MySQL +--------------------- + +On systems where both PCRE and MySQL are installed, it is possible to make use +of PCRE from within MySQL, as an alternative to the built-in pattern matching. +There is a web page that tells you how to do this: + + http://www.mysqludf.org/lib_mysqludf_preg/index.php + + +Making new tarballs +------------------- + +The command "make dist" creates three PCRE tarballs, in tar.gz, tar.bz2, and +zip formats. The command "make distcheck" does the same, but then does a trial +build of the new distribution to ensure that it works. + +If you have modified any of the man page sources in the doc directory, you +should first run the PrepareRelease script before making a distribution. This +script creates the .txt and HTML forms of the documentation from the man pages. + + +Testing PCRE +------------ + +To test the basic PCRE library on a Unix-like system, run the RunTest script. +There is another script called RunGrepTest that tests the options of the +pcregrep command. If the C++ wrapper library is built, three test programs +called pcrecpp_unittest, pcre_scanner_unittest, and pcre_stringpiece_unittest +are also built. When JIT support is enabled, another test program called +pcre_jit_test is built. + +Both the scripts and all the program tests are run if you obey "make check" or +"make test". For other environments, see the instructions in +NON-AUTOTOOLS-BUILD. + +The RunTest script runs the pcretest test program (which is documented in its +own man page) on each of the relevant testinput files in the testdata +directory, and compares the output with the contents of the corresponding +testoutput files. RunTest uses a file called testtry to hold the main output +from pcretest. Other files whose names begin with "test" are used as working +files in some tests. + +Some tests are relevant only when certain build-time options were selected. For +example, the tests for UTF-8/16/32 support are run only if --enable-utf was +used. RunTest outputs a comment when it skips a test. + +Many of the tests that are not skipped are run up to three times. The second +run forces pcre_study() to be called for all patterns except for a few in some +tests that are marked "never study" (see the pcretest program for how this is +done). If JIT support is available, the non-DFA tests are run a third time, +this time with a forced pcre_study() with the PCRE_STUDY_JIT_COMPILE option. +This testing can be suppressed by putting "nojit" on the RunTest command line. + +The entire set of tests is run once for each of the 8-bit, 16-bit and 32-bit +libraries that are enabled. If you want to run just one set of tests, call +RunTest with either the -8, -16 or -32 option. + +If valgrind is installed, you can run the tests under it by putting "valgrind" +on the RunTest command line. To run pcretest on just one or more specific test +files, give their numbers as arguments to RunTest, for example: + + RunTest 2 7 11 + +You can also specify ranges of tests such as 3-6 or 3- (meaning 3 to the +end), or a number preceded by ~ to exclude a test. For example: + + Runtest 3-15 ~10 + +This runs tests 3 to 15, excluding test 10, and just ~13 runs all the tests +except test 13. Whatever order the arguments are in, the tests are always run +in numerical order. + +You can also call RunTest with the single argument "list" to cause it to output +a list of tests. + +The first test file can be fed directly into the perltest.pl script to check +that Perl gives the same results. The only difference you should see is in the +first few lines, where the Perl version is given instead of the PCRE version. + +The second set of tests check pcre_fullinfo(), pcre_study(), +pcre_copy_substring(), pcre_get_substring(), pcre_get_substring_list(), error +detection, and run-time flags that are specific to PCRE, as well as the POSIX +wrapper API. It also uses the debugging flags to check some of the internals of +pcre_compile(). + +If you build PCRE with a locale setting that is not the standard C locale, the +character tables may be different (see next paragraph). In some cases, this may +cause failures in the second set of tests. For example, in a locale where the +isprint() function yields TRUE for characters in the range 128-255, the use of +[:isascii:] inside a character class defines a different set of characters, and +this shows up in this test as a difference in the compiled code, which is being +listed for checking. Where the comparison test output contains [\x00-\x7f] the +test will contain [\x00-\xff], and similarly in some other cases. This is not a +bug in PCRE. + +The third set of tests checks pcre_maketables(), the facility for building a +set of character tables for a specific locale and using them instead of the +default tables. The tests make use of the "fr_FR" (French) locale. Before +running the test, the script checks for the presence of this locale by running +the "locale" command. If that command fails, or if it doesn't include "fr_FR" +in the list of available locales, the third test cannot be run, and a comment +is output to say why. If running this test produces instances of the error + + ** Failed to set locale "fr_FR" + +in the comparison output, it means that locale is not available on your system, +despite being listed by "locale". This does not mean that PCRE is broken. + +[If you are trying to run this test on Windows, you may be able to get it to +work by changing "fr_FR" to "french" everywhere it occurs. Alternatively, use +RunTest.bat. The version of RunTest.bat included with PCRE 7.4 and above uses +Windows versions of test 2. More info on using RunTest.bat is included in the +document entitled NON-UNIX-USE.] + +The fourth and fifth tests check the UTF-8/16/32 support and error handling and +internal UTF features of PCRE that are not relevant to Perl, respectively. The +sixth and seventh tests do the same for Unicode character properties support. + +The eighth, ninth, and tenth tests check the pcre_dfa_exec() alternative +matching function, in non-UTF-8/16/32 mode, UTF-8/16/32 mode, and UTF-8/16/32 +mode with Unicode property support, respectively. + +The eleventh test checks some internal offsets and code size features; it is +run only when the default "link size" of 2 is set (in other cases the sizes +change) and when Unicode property support is enabled. + +The twelfth test is run only when JIT support is available, and the thirteenth +test is run only when JIT support is not available. They test some JIT-specific +features such as information output from pcretest about JIT compilation. + +The fourteenth, fifteenth, and sixteenth tests are run only in 8-bit mode, and +the seventeenth, eighteenth, and nineteenth tests are run only in 16/32-bit +mode. These are tests that generate different output in the two modes. They are +for general cases, UTF-8/16/32 support, and Unicode property support, +respectively. + +The twentieth test is run only in 16/32-bit mode. It tests some specific +16/32-bit features of the DFA matching engine. + +The twenty-first and twenty-second tests are run only in 16/32-bit mode, when +the link size is set to 2 for the 16-bit library. They test reloading +pre-compiled patterns. + +The twenty-third and twenty-fourth tests are run only in 16-bit mode. They are +for general cases, and UTF-16 support, respectively. + +The twenty-fifth and twenty-sixth tests are run only in 32-bit mode. They are +for general cases, and UTF-32 support, respectively. + + +Character tables +---------------- + +For speed, PCRE uses four tables for manipulating and identifying characters +whose code point values are less than 256. The final argument of the +pcre_compile() function is a pointer to a block of memory containing the +concatenated tables. A call to pcre_maketables() can be used to generate a set +of tables in the current locale. If the final argument for pcre_compile() is +passed as NULL, a set of default tables that is built into the binary is used. + +The source file called pcre_chartables.c contains the default set of tables. By +default, this is created as a copy of pcre_chartables.c.dist, which contains +tables for ASCII coding. However, if --enable-rebuild-chartables is specified +for ./configure, a different version of pcre_chartables.c is built by the +program dftables (compiled from dftables.c), which uses the ANSI C character +handling functions such as isalnum(), isalpha(), isupper(), islower(), etc. to +build the table sources. This means that the default C locale which is set for +your system will control the contents of these default tables. You can change +the default tables by editing pcre_chartables.c and then re-building PCRE. If +you do this, you should take care to ensure that the file does not get +automatically re-generated. The best way to do this is to move +pcre_chartables.c.dist out of the way and replace it with your customized +tables. + +When the dftables program is run as a result of --enable-rebuild-chartables, +it uses the default C locale that is set on your system. It does not pay +attention to the LC_xxx environment variables. In other words, it uses the +system's default locale rather than whatever the compiling user happens to have +set. If you really do want to build a source set of character tables in a +locale that is specified by the LC_xxx variables, you can run the dftables +program by hand with the -L option. For example: + + ./dftables -L pcre_chartables.c.special + +The first two 256-byte tables provide lower casing and case flipping functions, +respectively. The next table consists of three 32-byte bit maps which identify +digits, "word" characters, and white space, respectively. These are used when +building 32-byte bit maps that represent character classes for code points less +than 256. + +The final 256-byte table has bits indicating various character types, as +follows: + + 1 white space character + 2 letter + 4 decimal digit + 8 hexadecimal digit + 16 alphanumeric or '_' + 128 regular expression metacharacter or binary zero + +You should not alter the set of characters that contain the 128 bit, as that +will cause PCRE to malfunction. + + +File manifest +------------- + +The distribution should contain the files listed below. Where a file name is +given as pcre[16|32]_xxx it means that there are three files, one with the name +pcre_xxx, one with the name pcre16_xx, and a third with the name pcre32_xxx. + +(A) Source files of the PCRE library functions and their headers: + + dftables.c auxiliary program for building pcre_chartables.c + when --enable-rebuild-chartables is specified + + pcre_chartables.c.dist a default set of character tables that assume ASCII + coding; used, unless --enable-rebuild-chartables is + specified, by copying to pcre[16]_chartables.c + + pcreposix.c ) + pcre[16|32]_byte_order.c ) + pcre[16|32]_compile.c ) + pcre[16|32]_config.c ) + pcre[16|32]_dfa_exec.c ) + pcre[16|32]_exec.c ) + pcre[16|32]_fullinfo.c ) + pcre[16|32]_get.c ) sources for the functions in the library, + pcre[16|32]_globals.c ) and some internal functions that they use + pcre[16|32]_jit_compile.c ) + pcre[16|32]_maketables.c ) + pcre[16|32]_newline.c ) + pcre[16|32]_refcount.c ) + pcre[16|32]_string_utils.c ) + pcre[16|32]_study.c ) + pcre[16|32]_tables.c ) + pcre[16|32]_ucd.c ) + pcre[16|32]_version.c ) + pcre[16|32]_xclass.c ) + pcre_ord2utf8.c ) + pcre_valid_utf8.c ) + pcre16_ord2utf16.c ) + pcre16_utf16_utils.c ) + pcre16_valid_utf16.c ) + pcre32_utf32_utils.c ) + pcre32_valid_utf32.c ) + + pcre[16|32]_printint.c ) debugging function that is used by pcretest, + ) and can also be #included in pcre_compile() + + pcre.h.in template for pcre.h when built by "configure" + pcreposix.h header for the external POSIX wrapper API + pcre_internal.h header for internal use + sljit/* 16 files that make up the JIT compiler + ucp.h header for Unicode property handling + + config.h.in template for config.h, which is built by "configure" + + pcrecpp.h public header file for the C++ wrapper + pcrecpparg.h.in template for another C++ header file + pcre_scanner.h public header file for C++ scanner functions + pcrecpp.cc ) + pcre_scanner.cc ) source for the C++ wrapper library + + pcre_stringpiece.h.in template for pcre_stringpiece.h, the header for the + C++ stringpiece functions + pcre_stringpiece.cc source for the C++ stringpiece functions + +(B) Source files for programs that use PCRE: + + pcredemo.c simple demonstration of coding calls to PCRE + pcregrep.c source of a grep utility that uses PCRE + pcretest.c comprehensive test program + +(C) Auxiliary files: + + 132html script to turn "man" pages into HTML + AUTHORS information about the author of PCRE + ChangeLog log of changes to the code + CleanTxt script to clean nroff output for txt man pages + Detrail script to remove trailing spaces + HACKING some notes about the internals of PCRE + INSTALL generic installation instructions + LICENCE conditions for the use of PCRE + COPYING the same, using GNU's standard name + Makefile.in ) template for Unix Makefile, which is built by + ) "configure" + Makefile.am ) the automake input that was used to create + ) Makefile.in + NEWS important changes in this release + NON-UNIX-USE the previous name for NON-AUTOTOOLS-BUILD + NON-AUTOTOOLS-BUILD notes on building PCRE without using autotools + PrepareRelease script to make preparations for "make dist" + README this file + RunTest a Unix shell script for running tests + RunGrepTest a Unix shell script for pcregrep tests + aclocal.m4 m4 macros (generated by "aclocal") + config.guess ) files used by libtool, + config.sub ) used only when building a shared library + configure a configuring shell script (built by autoconf) + configure.ac ) the autoconf input that was used to build + ) "configure" and config.h + depcomp ) script to find program dependencies, generated by + ) automake + doc/*.3 man page sources for PCRE + doc/*.1 man page sources for pcregrep and pcretest + doc/index.html.src the base HTML page + doc/html/* HTML documentation + doc/pcre.txt plain text version of the man pages + doc/pcretest.txt plain text documentation of test program + doc/perltest.txt plain text documentation of Perl test program + install-sh a shell script for installing files + libpcre16.pc.in template for libpcre16.pc for pkg-config + libpcre32.pc.in template for libpcre32.pc for pkg-config + libpcre.pc.in template for libpcre.pc for pkg-config + libpcreposix.pc.in template for libpcreposix.pc for pkg-config + libpcrecpp.pc.in template for libpcrecpp.pc for pkg-config + ltmain.sh file used to build a libtool script + missing ) common stub for a few missing GNU programs while + ) installing, generated by automake + mkinstalldirs script for making install directories + perltest.pl Perl test program + pcre-config.in source of script which retains PCRE information + pcre_jit_test.c test program for the JIT compiler + pcrecpp_unittest.cc ) + pcre_scanner_unittest.cc ) test programs for the C++ wrapper + pcre_stringpiece_unittest.cc ) + testdata/testinput* test data for main library tests + testdata/testoutput* expected test results + testdata/grep* input and output for pcregrep tests + testdata/* other supporting test files + +(D) Auxiliary files for cmake support + + cmake/COPYING-CMAKE-SCRIPTS + cmake/FindPackageHandleStandardArgs.cmake + cmake/FindEditline.cmake + cmake/FindReadline.cmake + CMakeLists.txt + config-cmake.h.in + +(E) Auxiliary files for VPASCAL + + makevp.bat + makevp_c.txt + makevp_l.txt + pcregexp.pas + +(F) Auxiliary files for building PCRE "by hand" + + pcre.h.generic ) a version of the public PCRE header file + ) for use in non-"configure" environments + config.h.generic ) a version of config.h for use in non-"configure" + ) environments + +(F) Miscellaneous + + RunTest.bat a script for running tests under Windows + +Philip Hazel +Email local part: ph10 +Email domain: cam.ac.uk +Last updated: 17 January 2014 diff --git a/doc/html/index.html b/doc/html/index.html new file mode 100644 index 0000000..352c55d --- /dev/null +++ b/doc/html/index.html @@ -0,0 +1,185 @@ + + + +PCRE specification + + +

Perl-compatible Regular Expressions (PCRE)

+

+The HTML documentation for PCRE consists of a number of pages that are listed +below in alphabetical order. If you are new to PCRE, please read the first one +first. +

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
pcre  Introductory page
pcre-config  Information about the installation configuration
pcre16  Discussion of the 16-bit PCRE library
pcre32  Discussion of the 32-bit PCRE library
pcreapi  PCRE's native API
pcrebuild  Building PCRE
pcrecallout  The callout facility
pcrecompat  Compability with Perl
pcrecpp  The C++ wrapper for the PCRE library
pcredemo  A demonstration C program that uses the PCRE library
pcregrep  The pcregrep command
pcrejit  Discussion of the just-in-time optimization support
pcrelimits  Details of size and other limits
pcrematching  Discussion of the two matching algorithms
pcrepartial  Using PCRE for partial matching
pcrepattern  Specification of the regular expressions supported by PCRE
pcreperform  Some comments on performance
pcreposix  The POSIX API to the PCRE 8-bit library
pcreprecompile  How to save and re-use compiled patterns
pcresample  Discussion of the pcredemo program
pcrestack  Discussion of PCRE's stack usage
pcresyntax  Syntax quick-reference summary
pcretest  The pcretest command for testing PCRE
pcreunicode  Discussion of Unicode and UTF-8/UTF-16/UTF-32 support
+ +

+There are also individual pages that summarize the interface for each function +in the library. There is a single page for each triple of 8-bit/16-bit/32-bit +functions. +

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
pcre_assign_jit_stack  Assign stack for JIT matching
pcre_compile  Compile a regular expression
pcre_compile2  Compile a regular expression (alternate interface)
pcre_config  Show build-time configuration options
pcre_copy_named_substring  Extract named substring into given buffer
pcre_copy_substring  Extract numbered substring into given buffer
pcre_dfa_exec  Match a compiled pattern to a subject string + (DFA algorithm; not Perl compatible)
pcre_exec  Match a compiled pattern to a subject string + (Perl compatible)
pcre_free_study  Free study data
pcre_free_substring  Free extracted substring
pcre_free_substring_list  Free list of extracted substrings
pcre_fullinfo  Extract information about a pattern
pcre_get_named_substring  Extract named substring into new memory
pcre_get_stringnumber  Convert captured string name to number
pcre_get_stringtable_entries  Find table entries for given string name
pcre_get_substring  Extract numbered substring into new memory
pcre_get_substring_list  Extract all substrings into new memory
pcre_jit_exec  Fast path interface to JIT matching
pcre_jit_stack_alloc  Create a stack for JIT matching
pcre_jit_stack_free  Free a JIT matching stack
pcre_maketables  Build character tables in current locale
pcre_pattern_to_host_byte_order  Convert compiled pattern to host byte order if necessary
pcre_refcount  Maintain reference count in compiled pattern
pcre_study  Study a compiled pattern
pcre_utf16_to_host_byte_order  Convert UTF-16 string to host byte order if necessary
pcre_utf32_to_host_byte_order  Convert UTF-32 string to host byte order if necessary
pcre_version  Return PCRE version and release date
+ + diff --git a/doc/html/pcre-config.html b/doc/html/pcre-config.html new file mode 100644 index 0000000..56a8060 --- /dev/null +++ b/doc/html/pcre-config.html @@ -0,0 +1,109 @@ + + +pcre-config specification + + +

pcre-config man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+

+
SYNOPSIS
+

+pcre-config [--prefix] [--exec-prefix] [--version] [--libs] + [--libs16] [--libs32] [--libs-cpp] [--libs-posix] + [--cflags] [--cflags-posix] +

+
DESCRIPTION
+

+pcre-config returns the configuration of the installed PCRE +libraries and the options required to compile a program to use them. Some of +the options apply only to the 8-bit, or 16-bit, or 32-bit libraries, +respectively, and are +not available if only one of those libraries has been built. If an unavailable +option is encountered, the "usage" information is output. +

+
OPTIONS
+

+--prefix +Writes the directory prefix used in the PCRE installation for architecture +independent files (/usr on many systems, /usr/local on some +systems) to the standard output. +

+

+--exec-prefix +Writes the directory prefix used in the PCRE installation for architecture +dependent files (normally the same as --prefix) to the standard output. +

+

+--version +Writes the version number of the installed PCRE libraries to the standard +output. +

+

+--libs +Writes to the standard output the command line options required to link +with the 8-bit PCRE library (-lpcre on many systems). +

+

+--libs16 +Writes to the standard output the command line options required to link +with the 16-bit PCRE library (-lpcre16 on many systems). +

+

+--libs32 +Writes to the standard output the command line options required to link +with the 32-bit PCRE library (-lpcre32 on many systems). +

+

+--libs-cpp +Writes to the standard output the command line options required to link with +PCRE's C++ wrapper library (-lpcrecpp -lpcre on many +systems). +

+

+--libs-posix +Writes to the standard output the command line options required to link with +PCRE's POSIX API wrapper library (-lpcreposix -lpcre on many +systems). +

+

+--cflags +Writes to the standard output the command line options required to compile +files that use PCRE (this may include some -I options, but is blank on +many systems). +

+

+--cflags-posix +Writes to the standard output the command line options required to compile +files that use PCRE's POSIX API wrapper library (this may include some -I +options, but is blank on many systems). +

+
SEE ALSO
+

+pcre(3) +

+
AUTHOR
+

+This manual page was originally written by Mark Baker for the Debian GNU/Linux +system. It has been subsequently revised as a generic PCRE man page. +

+
REVISION
+

+Last updated: 24 June 2012 +
+

+Return to the PCRE index page. +

diff --git a/doc/html/pcre.html b/doc/html/pcre.html new file mode 100644 index 0000000..c2b29aa --- /dev/null +++ b/doc/html/pcre.html @@ -0,0 +1,213 @@ + + +pcre specification + + +

pcre man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+

+
INTRODUCTION
+

+The PCRE library is a set of functions that implement regular expression +pattern matching using the same syntax and semantics as Perl, with just a few +differences. Some features that appeared in Python and PCRE before they +appeared in Perl are also available using the Python syntax, there is some +support for one or two .NET and Oniguruma syntax items, and there is an option +for requesting some minor changes that give better JavaScript compatibility. +

+

+Starting with release 8.30, it is possible to compile two separate PCRE +libraries: the original, which supports 8-bit character strings (including +UTF-8 strings), and a second library that supports 16-bit character strings +(including UTF-16 strings). The build process allows either one or both to be +built. The majority of the work to make this possible was done by Zoltan +Herczeg. +

+

+Starting with release 8.32 it is possible to compile a third separate PCRE +library that supports 32-bit character strings (including UTF-32 strings). The +build process allows any combination of the 8-, 16- and 32-bit libraries. The +work to make this possible was done by Christian Persch. +

+

+The three libraries contain identical sets of functions, except that the names +in the 16-bit library start with pcre16_ instead of pcre_, and the +names in the 32-bit library start with pcre32_ instead of pcre_. To +avoid over-complication and reduce the documentation maintenance load, most of +the documentation describes the 8-bit library, with the differences for the +16-bit and 32-bit libraries described separately in the +pcre16 +and +pcre32 +pages. References to functions or structures of the form pcre[16|32]_xxx +should be read as meaning "pcre_xxx when using the 8-bit library, +pcre16_xxx when using the 16-bit library, or pcre32_xxx when using +the 32-bit library". +

+

+The current implementation of PCRE corresponds approximately with Perl 5.12, +including support for UTF-8/16/32 encoded strings and Unicode general category +properties. However, UTF-8/16/32 and Unicode support has to be explicitly +enabled; it is not the default. The Unicode tables correspond to Unicode +release 6.3.0. +

+

+In addition to the Perl-compatible matching function, PCRE contains an +alternative function that matches the same compiled patterns in a different +way. In certain circumstances, the alternative function has some advantages. +For a discussion of the two matching algorithms, see the +pcrematching +page. +

+

+PCRE is written in C and released as a C library. A number of people have +written wrappers and interfaces of various kinds. In particular, Google Inc. +have provided a comprehensive C++ wrapper for the 8-bit library. This is now +included as part of the PCRE distribution. The +pcrecpp +page has details of this interface. Other people's contributions can be found +in the Contrib directory at the primary FTP site, which is: +ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre +

+

+Details of exactly which Perl regular expression features are and are not +supported by PCRE are given in separate documents. See the +pcrepattern +and +pcrecompat +pages. There is a syntax summary in the +pcresyntax +page. +

+

+Some features of PCRE can be included, excluded, or changed when the library is +built. The +pcre_config() +function makes it possible for a client to discover which features are +available. The features themselves are described in the +pcrebuild +page. Documentation about building PCRE for various operating systems can be +found in the +README +and +NON-AUTOTOOLS_BUILD +files in the source distribution. +

+

+The libraries contains a number of undocumented internal functions and data +tables that are used by more than one of the exported external functions, but +which are not intended for use by external callers. Their names all begin with +"_pcre_" or "_pcre16_" or "_pcre32_", which hopefully will not provoke any name +clashes. In some environments, it is possible to control which external symbols +are exported when a shared library is built, and in these cases the +undocumented symbols are not exported. +

+
SECURITY CONSIDERATIONS
+

+If you are using PCRE in a non-UTF application that permits users to supply +arbitrary patterns for compilation, you should be aware of a feature that +allows users to turn on UTF support from within a pattern, provided that PCRE +was built with UTF support. For example, an 8-bit pattern that begins with +"(*UTF8)" or "(*UTF)" turns on UTF-8 mode, which interprets patterns and +subjects as strings of UTF-8 characters instead of individual 8-bit characters. +This causes both the pattern and any data against which it is matched to be +checked for UTF-8 validity. If the data string is very long, such a check might +use sufficiently many resources as to cause your application to lose +performance. +

+

+One way of guarding against this possibility is to use the +pcre_fullinfo() function to check the compiled pattern's options for UTF. +Alternatively, from release 8.33, you can set the PCRE_NEVER_UTF option at +compile time. This causes an compile time error if a pattern contains a +UTF-setting sequence. +

+

+If your application is one that supports UTF, be aware that validity checking +can take time. If the same data string is to be matched many times, you can use +the PCRE_NO_UTF[8|16|32]_CHECK option for the second and subsequent matches to +save redundant checks. +

+

+Another way that performance can be hit is by running a pattern that has a very +large search tree against a string that will never match. Nested unlimited +repeats in a pattern are a common example. PCRE provides some protection +against this: see the PCRE_EXTRA_MATCH_LIMIT feature in the +pcreapi +page. +

+
USER DOCUMENTATION
+

+The user documentation for PCRE comprises a number of different sections. In +the "man" format, each of these is a separate "man page". In the HTML format, +each is a separate page, linked from the index page. In the plain text format, +the descriptions of the pcregrep and pcretest programs are in files +called pcregrep.txt and pcretest.txt, respectively. The remaining +sections, except for the pcredemo section (which is a program listing), +are concatenated in pcre.txt, for ease of searching. The sections are as +follows: +

+  pcre              this document
+  pcre-config       show PCRE installation configuration information
+  pcre16            details of the 16-bit library
+  pcre32            details of the 32-bit library
+  pcreapi           details of PCRE's native C API
+  pcrebuild         building PCRE
+  pcrecallout       details of the callout feature
+  pcrecompat        discussion of Perl compatibility
+  pcrecpp           details of the C++ wrapper for the 8-bit library
+  pcredemo          a demonstration C program that uses PCRE
+  pcregrep          description of the pcregrep command (8-bit only)
+  pcrejit           discussion of the just-in-time optimization support
+  pcrelimits        details of size and other limits
+  pcrematching      discussion of the two matching algorithms
+  pcrepartial       details of the partial matching facility
+  pcrepattern       syntax and semantics of supported regular expressions
+  pcreperform       discussion of performance issues
+  pcreposix         the POSIX-compatible C API for the 8-bit library
+  pcreprecompile    details of saving and re-using precompiled patterns
+  pcresample        discussion of the pcredemo program
+  pcrestack         discussion of stack usage
+  pcresyntax        quick syntax reference
+  pcretest          description of the pcretest testing command
+  pcreunicode       discussion of Unicode and UTF-8/16/32 support
+
+In the "man" and HTML formats, there is also a short page for each C library +function, listing its arguments and results. +

+
AUTHOR
+

+Philip Hazel +
+University Computing Service +
+Cambridge CB2 3QH, England. +
+

+

+Putting an actual email address here seems to have been a spam magnet, so I've +taken it away. If you want to email me, use my two initials, followed by the +two digits 10, at the domain cam.ac.uk. +

+
REVISION
+

+Last updated: 08 January 2014 +
+Copyright © 1997-2014 University of Cambridge. +
+

+Return to the PCRE index page. +

diff --git a/doc/html/pcre16.html b/doc/html/pcre16.html new file mode 100644 index 0000000..f00859f --- /dev/null +++ b/doc/html/pcre16.html @@ -0,0 +1,384 @@ + + +pcre16 specification + + +

pcre16 man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+

+

+#include <pcre.h> +

+
PCRE 16-BIT API BASIC FUNCTIONS
+

+pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options, + int *errorcodeptr, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre16_extra *pcre16_study(const pcre16 *code, int options, + const char **errptr); +
+
+void pcre16_free_study(pcre16_extra *extra); +
+
+int pcre16_exec(const pcre16 *code, const pcre16_extra *extra, + PCRE_SPTR16 subject, int length, int startoffset, + int options, int *ovector, int ovecsize); +
+
+int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra, + PCRE_SPTR16 subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + int *workspace, int wscount); +

+
PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
+

+int pcre16_copy_named_substring(const pcre16 *code, + PCRE_SPTR16 subject, int *ovector, + int stringcount, PCRE_SPTR16 stringname, + PCRE_UCHAR16 *buffer, int buffersize); +
+
+int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector, + int stringcount, int stringnumber, PCRE_UCHAR16 *buffer, + int buffersize); +
+
+int pcre16_get_named_substring(const pcre16 *code, + PCRE_SPTR16 subject, int *ovector, + int stringcount, PCRE_SPTR16 stringname, + PCRE_SPTR16 *stringptr); +
+
+int pcre16_get_stringnumber(const pcre16 *code, +" PCRE_SPTR16 name); +
+
+int pcre16_get_stringtable_entries(const pcre16 *code, + PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last); +
+
+int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector, + int stringcount, int stringnumber, + PCRE_SPTR16 *stringptr); +
+
+int pcre16_get_substring_list(PCRE_SPTR16 subject, + int *ovector, int stringcount, PCRE_SPTR16 **listptr); +
+
+void pcre16_free_substring(PCRE_SPTR16 stringptr); +
+
+void pcre16_free_substring_list(PCRE_SPTR16 *stringptr); +

+
PCRE 16-BIT API AUXILIARY FUNCTIONS
+

+pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize); +
+
+void pcre16_jit_stack_free(pcre16_jit_stack *stack); +
+
+void pcre16_assign_jit_stack(pcre16_extra *extra, + pcre16_jit_callback callback, void *data); +
+
+const unsigned char *pcre16_maketables(void); +
+
+int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra, + int what, void *where); +
+
+int pcre16_refcount(pcre16 *code, int adjust); +
+
+int pcre16_config(int what, void *where); +
+
+const char *pcre16_version(void); +
+
+int pcre16_pattern_to_host_byte_order(pcre16 *code, + pcre16_extra *extra, const unsigned char *tables); +

+
PCRE 16-BIT API INDIRECTED FUNCTIONS
+

+void *(*pcre16_malloc)(size_t); +
+
+void (*pcre16_free)(void *); +
+
+void *(*pcre16_stack_malloc)(size_t); +
+
+void (*pcre16_stack_free)(void *); +
+
+int (*pcre16_callout)(pcre16_callout_block *); +

+
PCRE 16-BIT API 16-BIT-ONLY FUNCTION
+

+int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output, + PCRE_SPTR16 input, int length, int *byte_order, + int keep_boms); +

+
THE PCRE 16-BIT LIBRARY
+

+Starting with release 8.30, it is possible to compile a PCRE library that +supports 16-bit character strings, including UTF-16 strings, as well as or +instead of the original 8-bit library. The majority of the work to make this +possible was done by Zoltan Herczeg. The two libraries contain identical sets +of functions, used in exactly the same way. Only the names of the functions and +the data types of their arguments and results are different. To avoid +over-complication and reduce the documentation maintenance load, most of the +PCRE documentation describes the 8-bit library, with only occasional references +to the 16-bit library. This page describes what is different when you use the +16-bit library. +

+

+WARNING: A single application can be linked with both libraries, but you must +take care when processing any particular pattern to use functions from just one +library. For example, if you want to study a pattern that was compiled with +pcre16_compile(), you must do so with pcre16_study(), not +pcre_study(), and you must free the study data with +pcre16_free_study(). +

+
THE HEADER FILE
+

+There is only one header file, pcre.h. It contains prototypes for all the +functions in all libraries, as well as definitions of flags, structures, error +codes, etc. +

+
THE LIBRARY NAME
+

+In Unix-like systems, the 16-bit library is called libpcre16, and can +normally be accesss by adding -lpcre16 to the command for linking an +application that uses PCRE. +

+
STRING TYPES
+

+In the 8-bit library, strings are passed to PCRE library functions as vectors +of bytes with the C type "char *". In the 16-bit library, strings are passed as +vectors of unsigned 16-bit quantities. The macro PCRE_UCHAR16 specifies an +appropriate data type, and PCRE_SPTR16 is defined as "const PCRE_UCHAR16 *". In +very many environments, "short int" is a 16-bit data type. When PCRE is built, +it defines PCRE_UCHAR16 as "unsigned short int", but checks that it really is a +16-bit data type. If it is not, the build fails with an error message telling +the maintainer to modify the definition appropriately. +

+
STRUCTURE TYPES
+

+The types of the opaque structures that are used for compiled 16-bit patterns +and JIT stacks are pcre16 and pcre16_jit_stack respectively. The +type of the user-accessible structure that is returned by pcre16_study() +is pcre16_extra, and the type of the structure that is used for passing +data to a callout function is pcre16_callout_block. These structures +contain the same fields, with the same names, as their 8-bit counterparts. The +only difference is that pointers to character strings are 16-bit instead of +8-bit types. +

+
16-BIT FUNCTIONS
+

+For every function in the 8-bit library there is a corresponding function in +the 16-bit library with a name that starts with pcre16_ instead of +pcre_. The prototypes are listed above. In addition, there is one extra +function, pcre16_utf16_to_host_byte_order(). This is a utility function +that converts a UTF-16 character string to host byte order if necessary. The +other 16-bit functions expect the strings they are passed to be in host byte +order. +

+

+The input and output arguments of +pcre16_utf16_to_host_byte_order() may point to the same address, that is, +conversion in place is supported. The output buffer must be at least as long as +the input. +

+

+The length argument specifies the number of 16-bit data units in the +input string; a negative value specifies a zero-terminated string. +

+

+If byte_order is NULL, it is assumed that the string starts off in host +byte order. This may be changed by byte-order marks (BOMs) anywhere in the +string (commonly as the first character). +

+

+If byte_order is not NULL, a non-zero value of the integer to which it +points means that the input starts off in host byte order, otherwise the +opposite order is assumed. Again, BOMs in the string can change this. The final +byte order is passed back at the end of processing. +

+

+If keep_boms is not zero, byte-order mark characters (0xfeff) are copied +into the output string. Otherwise they are discarded. +

+

+The result of the function is the number of 16-bit units placed into the output +buffer, including the zero terminator if the string was zero-terminated. +

+
SUBJECT STRING OFFSETS
+

+The lengths and starting offsets of subject strings must be specified in 16-bit +data units, and the offsets within subject strings that are returned by the +matching functions are in also 16-bit units rather than bytes. +

+
NAMED SUBPATTERNS
+

+The name-to-number translation table that is maintained for named subpatterns +uses 16-bit characters. The pcre16_get_stringtable_entries() function +returns the length of each entry in the table as the number of 16-bit data +units. +

+
OPTION NAMES
+

+There are two new general option names, PCRE_UTF16 and PCRE_NO_UTF16_CHECK, +which correspond to PCRE_UTF8 and PCRE_NO_UTF8_CHECK in the 8-bit library. In +fact, these new options define the same bits in the options word. There is a +discussion about the +validity of UTF-16 strings +in the +pcreunicode +page. +

+

+For the pcre16_config() function there is an option PCRE_CONFIG_UTF16 +that returns 1 if UTF-16 support is configured, otherwise 0. If this option is +given to pcre_config() or pcre32_config(), or if the +PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF32 option is given to pcre16_config(), +the result is the PCRE_ERROR_BADOPTION error. +

+
CHARACTER CODES
+

+In 16-bit mode, when PCRE_UTF16 is not set, character values are treated in the +same way as in 8-bit, non UTF-8 mode, except, of course, that they can range +from 0 to 0xffff instead of 0 to 0xff. Character types for characters less than +0xff can therefore be influenced by the locale in the same way as before. +Characters greater than 0xff have only one case, and no "type" (such as letter +or digit). +

+

+In UTF-16 mode, the character code is Unicode, in the range 0 to 0x10ffff, with +the exception of values in the range 0xd800 to 0xdfff because those are +"surrogate" values that are used in pairs to encode values greater than 0xffff. +

+

+A UTF-16 string can indicate its endianness by special code knows as a +byte-order mark (BOM). The PCRE functions do not handle this, expecting strings +to be in host byte order. A utility function called +pcre16_utf16_to_host_byte_order() is provided to help with this (see +above). +

+
ERROR NAMES
+

+The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16 correspond to +their 8-bit counterparts. The error PCRE_ERROR_BADMODE is given when a compiled +pattern is passed to a function that processes patterns in the other +mode, for example, if a pattern compiled with pcre_compile() is passed to +pcre16_exec(). +

+

+There are new error codes whose names begin with PCRE_UTF16_ERR for invalid +UTF-16 strings, corresponding to the PCRE_UTF8_ERR codes for UTF-8 strings that +are described in the section entitled +"Reason codes for invalid UTF-8 strings" +in the main +pcreapi +page. The UTF-16 errors are: +

+  PCRE_UTF16_ERR1  Missing low surrogate at end of string
+  PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
+  PCRE_UTF16_ERR3  Isolated low surrogate
+  PCRE_UTF16_ERR4  Non-character
+
+

+
ERROR TEXTS
+

+If there is an error while compiling a pattern, the error text that is passed +back by pcre16_compile() or pcre16_compile2() is still an 8-bit +character string, zero-terminated. +

+
CALLOUTS
+

+The subject and mark fields in the callout block that is passed to +a callout function point to 16-bit vectors. +

+
TESTING
+

+The pcretest program continues to operate with 8-bit input and output +files, but it can be used for testing the 16-bit library. If it is run with the +command line option -16, patterns and subject strings are converted from +8-bit to 16-bit before being passed to PCRE, and the 16-bit library functions +are used instead of the 8-bit ones. Returned 16-bit strings are converted to +8-bit for output. If both the 8-bit and the 32-bit libraries were not compiled, +pcretest defaults to 16-bit and the -16 option is ignored. +

+

+When PCRE is being built, the RunTest script that is called by "make +check" uses the pcretest -C option to discover which of the 8-bit, +16-bit and 32-bit libraries has been built, and runs the tests appropriately. +

+
NOT SUPPORTED IN 16-BIT MODE
+

+Not all the features of the 8-bit library are available with the 16-bit +library. The C++ and POSIX wrapper functions support only the 8-bit library, +and the pcregrep program is at present 8-bit only. +

+
AUTHOR
+

+Philip Hazel +
+University Computing Service +
+Cambridge CB2 3QH, England. +
+

+
REVISION
+

+Last updated: 12 May 2013 +
+Copyright © 1997-2013 University of Cambridge. +
+

+Return to the PCRE index page. +

diff --git a/doc/html/pcre32.html b/doc/html/pcre32.html new file mode 100644 index 0000000..f96876e --- /dev/null +++ b/doc/html/pcre32.html @@ -0,0 +1,382 @@ + + +pcre32 specification + + +

pcre32 man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+

+

+#include <pcre.h> +

+
PCRE 32-BIT API BASIC FUNCTIONS
+

+pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options, + int *errorcodeptr, + const unsigned char *tableptr); +
+
+pcre32_extra *pcre32_study(const pcre32 *code, int options, + const char **errptr); +
+
+void pcre32_free_study(pcre32_extra *extra); +
+
+int pcre32_exec(const pcre32 *code, const pcre32_extra *extra, + PCRE_SPTR32 subject, int length, int startoffset, + int options, int *ovector, int ovecsize); +
+
+int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra, + PCRE_SPTR32 subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + int *workspace, int wscount); +

+
PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
+

+int pcre32_copy_named_substring(const pcre32 *code, + PCRE_SPTR32 subject, int *ovector, + int stringcount, PCRE_SPTR32 stringname, + PCRE_UCHAR32 *buffer, int buffersize); +
+
+int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector, + int stringcount, int stringnumber, PCRE_UCHAR32 *buffer, + int buffersize); +
+
+int pcre32_get_named_substring(const pcre32 *code, + PCRE_SPTR32 subject, int *ovector, + int stringcount, PCRE_SPTR32 stringname, + PCRE_SPTR32 *stringptr); +
+
+int pcre32_get_stringnumber(const pcre32 *code, + PCRE_SPTR32 name); +
+
+int pcre32_get_stringtable_entries(const pcre32 *code, + PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last); +
+
+int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector, + int stringcount, int stringnumber, + PCRE_SPTR32 *stringptr); +
+
+int pcre32_get_substring_list(PCRE_SPTR32 subject, + int *ovector, int stringcount, PCRE_SPTR32 **listptr); +
+
+void pcre32_free_substring(PCRE_SPTR32 stringptr); +
+
+void pcre32_free_substring_list(PCRE_SPTR32 *stringptr); +

+
PCRE 32-BIT API AUXILIARY FUNCTIONS
+

+pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize); +
+
+void pcre32_jit_stack_free(pcre32_jit_stack *stack); +
+
+void pcre32_assign_jit_stack(pcre32_extra *extra, + pcre32_jit_callback callback, void *data); +
+
+const unsigned char *pcre32_maketables(void); +
+
+int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra, + int what, void *where); +
+
+int pcre32_refcount(pcre32 *code, int adjust); +
+
+int pcre32_config(int what, void *where); +
+
+const char *pcre32_version(void); +
+
+int pcre32_pattern_to_host_byte_order(pcre32 *code, + pcre32_extra *extra, const unsigned char *tables); +

+
PCRE 32-BIT API INDIRECTED FUNCTIONS
+

+void *(*pcre32_malloc)(size_t); +
+
+void (*pcre32_free)(void *); +
+
+void *(*pcre32_stack_malloc)(size_t); +
+
+void (*pcre32_stack_free)(void *); +
+
+int (*pcre32_callout)(pcre32_callout_block *); +

+
PCRE 32-BIT API 32-BIT-ONLY FUNCTION
+

+int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output, + PCRE_SPTR32 input, int length, int *byte_order, + int keep_boms); +

+
THE PCRE 32-BIT LIBRARY
+

+Starting with release 8.32, it is possible to compile a PCRE library that +supports 32-bit character strings, including UTF-32 strings, as well as or +instead of the original 8-bit library. This work was done by Christian Persch, +based on the work done by Zoltan Herczeg for the 16-bit library. All three +libraries contain identical sets of functions, used in exactly the same way. +Only the names of the functions and the data types of their arguments and +results are different. To avoid over-complication and reduce the documentation +maintenance load, most of the PCRE documentation describes the 8-bit library, +with only occasional references to the 16-bit and 32-bit libraries. This page +describes what is different when you use the 32-bit library. +

+

+WARNING: A single application can be linked with all or any of the three +libraries, but you must take care when processing any particular pattern +to use functions from just one library. For example, if you want to study +a pattern that was compiled with pcre32_compile(), you must do so +with pcre32_study(), not pcre_study(), and you must free the +study data with pcre32_free_study(). +

+
THE HEADER FILE
+

+There is only one header file, pcre.h. It contains prototypes for all the +functions in all libraries, as well as definitions of flags, structures, error +codes, etc. +

+
THE LIBRARY NAME
+

+In Unix-like systems, the 32-bit library is called libpcre32, and can +normally be accesss by adding -lpcre32 to the command for linking an +application that uses PCRE. +

+
STRING TYPES
+

+In the 8-bit library, strings are passed to PCRE library functions as vectors +of bytes with the C type "char *". In the 32-bit library, strings are passed as +vectors of unsigned 32-bit quantities. The macro PCRE_UCHAR32 specifies an +appropriate data type, and PCRE_SPTR32 is defined as "const PCRE_UCHAR32 *". In +very many environments, "unsigned int" is a 32-bit data type. When PCRE is +built, it defines PCRE_UCHAR32 as "unsigned int", but checks that it really is +a 32-bit data type. If it is not, the build fails with an error message telling +the maintainer to modify the definition appropriately. +

+
STRUCTURE TYPES
+

+The types of the opaque structures that are used for compiled 32-bit patterns +and JIT stacks are pcre32 and pcre32_jit_stack respectively. The +type of the user-accessible structure that is returned by pcre32_study() +is pcre32_extra, and the type of the structure that is used for passing +data to a callout function is pcre32_callout_block. These structures +contain the same fields, with the same names, as their 8-bit counterparts. The +only difference is that pointers to character strings are 32-bit instead of +8-bit types. +

+
32-BIT FUNCTIONS
+

+For every function in the 8-bit library there is a corresponding function in +the 32-bit library with a name that starts with pcre32_ instead of +pcre_. The prototypes are listed above. In addition, there is one extra +function, pcre32_utf32_to_host_byte_order(). This is a utility function +that converts a UTF-32 character string to host byte order if necessary. The +other 32-bit functions expect the strings they are passed to be in host byte +order. +

+

+The input and output arguments of +pcre32_utf32_to_host_byte_order() may point to the same address, that is, +conversion in place is supported. The output buffer must be at least as long as +the input. +

+

+The length argument specifies the number of 32-bit data units in the +input string; a negative value specifies a zero-terminated string. +

+

+If byte_order is NULL, it is assumed that the string starts off in host +byte order. This may be changed by byte-order marks (BOMs) anywhere in the +string (commonly as the first character). +

+

+If byte_order is not NULL, a non-zero value of the integer to which it +points means that the input starts off in host byte order, otherwise the +opposite order is assumed. Again, BOMs in the string can change this. The final +byte order is passed back at the end of processing. +

+

+If keep_boms is not zero, byte-order mark characters (0xfeff) are copied +into the output string. Otherwise they are discarded. +

+

+The result of the function is the number of 32-bit units placed into the output +buffer, including the zero terminator if the string was zero-terminated. +

+
SUBJECT STRING OFFSETS
+

+The lengths and starting offsets of subject strings must be specified in 32-bit +data units, and the offsets within subject strings that are returned by the +matching functions are in also 32-bit units rather than bytes. +

+
NAMED SUBPATTERNS
+

+The name-to-number translation table that is maintained for named subpatterns +uses 32-bit characters. The pcre32_get_stringtable_entries() function +returns the length of each entry in the table as the number of 32-bit data +units. +

+
OPTION NAMES
+

+There are two new general option names, PCRE_UTF32 and PCRE_NO_UTF32_CHECK, +which correspond to PCRE_UTF8 and PCRE_NO_UTF8_CHECK in the 8-bit library. In +fact, these new options define the same bits in the options word. There is a +discussion about the +validity of UTF-32 strings +in the +pcreunicode +page. +

+

+For the pcre32_config() function there is an option PCRE_CONFIG_UTF32 +that returns 1 if UTF-32 support is configured, otherwise 0. If this option is +given to pcre_config() or pcre16_config(), or if the +PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF16 option is given to pcre32_config(), +the result is the PCRE_ERROR_BADOPTION error. +

+
CHARACTER CODES
+

+In 32-bit mode, when PCRE_UTF32 is not set, character values are treated in the +same way as in 8-bit, non UTF-8 mode, except, of course, that they can range +from 0 to 0x7fffffff instead of 0 to 0xff. Character types for characters less +than 0xff can therefore be influenced by the locale in the same way as before. +Characters greater than 0xff have only one case, and no "type" (such as letter +or digit). +

+

+In UTF-32 mode, the character code is Unicode, in the range 0 to 0x10ffff, with +the exception of values in the range 0xd800 to 0xdfff because those are +"surrogate" values that are ill-formed in UTF-32. +

+

+A UTF-32 string can indicate its endianness by special code knows as a +byte-order mark (BOM). The PCRE functions do not handle this, expecting strings +to be in host byte order. A utility function called +pcre32_utf32_to_host_byte_order() is provided to help with this (see +above). +

+
ERROR NAMES
+

+The error PCRE_ERROR_BADUTF32 corresponds to its 8-bit counterpart. +The error PCRE_ERROR_BADMODE is given when a compiled +pattern is passed to a function that processes patterns in the other +mode, for example, if a pattern compiled with pcre_compile() is passed to +pcre32_exec(). +

+

+There are new error codes whose names begin with PCRE_UTF32_ERR for invalid +UTF-32 strings, corresponding to the PCRE_UTF8_ERR codes for UTF-8 strings that +are described in the section entitled +"Reason codes for invalid UTF-8 strings" +in the main +pcreapi +page. The UTF-32 errors are: +

+  PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
+  PCRE_UTF32_ERR2  Non-character
+  PCRE_UTF32_ERR3  Character > 0x10ffff
+
+

+
ERROR TEXTS
+

+If there is an error while compiling a pattern, the error text that is passed +back by pcre32_compile() or pcre32_compile2() is still an 8-bit +character string, zero-terminated. +

+
CALLOUTS
+

+The subject and mark fields in the callout block that is passed to +a callout function point to 32-bit vectors. +

+
TESTING
+

+The pcretest program continues to operate with 8-bit input and output +files, but it can be used for testing the 32-bit library. If it is run with the +command line option -32, patterns and subject strings are converted from +8-bit to 32-bit before being passed to PCRE, and the 32-bit library functions +are used instead of the 8-bit ones. Returned 32-bit strings are converted to +8-bit for output. If both the 8-bit and the 16-bit libraries were not compiled, +pcretest defaults to 32-bit and the -32 option is ignored. +

+

+When PCRE is being built, the RunTest script that is called by "make +check" uses the pcretest -C option to discover which of the 8-bit, +16-bit and 32-bit libraries has been built, and runs the tests appropriately. +

+
NOT SUPPORTED IN 32-BIT MODE
+

+Not all the features of the 8-bit library are available with the 32-bit +library. The C++ and POSIX wrapper functions support only the 8-bit library, +and the pcregrep program is at present 8-bit only. +

+
AUTHOR
+

+Philip Hazel +
+University Computing Service +
+Cambridge CB2 3QH, England. +
+

+
REVISION
+

+Last updated: 12 May 2013 +
+Copyright © 1997-2013 University of Cambridge. +
+

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_assign_jit_stack.html b/doc/html/pcre_assign_jit_stack.html new file mode 100644 index 0000000..b2eef70 --- /dev/null +++ b/doc/html/pcre_assign_jit_stack.html @@ -0,0 +1,76 @@ + + +pcre_assign_jit_stack specification + + +

pcre_assign_jit_stack man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+void pcre_assign_jit_stack(pcre_extra *extra, + pcre_jit_callback callback, void *data); +
+
+void pcre16_assign_jit_stack(pcre16_extra *extra, + pcre16_jit_callback callback, void *data); +
+
+void pcre32_assign_jit_stack(pcre32_extra *extra, + pcre32_jit_callback callback, void *data); +

+
+DESCRIPTION +
+

+This function provides control over the memory used as a stack at run-time by a +call to pcre[16|32]_exec() with a pattern that has been successfully +compiled with JIT optimization. The arguments are: +

+  extra     the data pointer returned by pcre[16|32]_study()
+  callback  a callback function
+  data      a JIT stack or a value to be passed to the callback
+              function
+
+

+

+If callback is NULL and data is NULL, an internal 32K block on +the machine stack is used. +

+

+If callback is NULL and data is not NULL, data must +be a valid JIT stack, the result of calling pcre[16|32]_jit_stack_alloc(). +

+

+If callback not NULL, it is called with data as an argument at +the start of matching, in order to set up a JIT stack. If the result is NULL, +the internal 32K stack is used; otherwise the return value must be a valid JIT +stack, the result of calling pcre[16|32]_jit_stack_alloc(). +

+

+You may safely assign the same JIT stack to multiple patterns, as long as they +are all matched in the same thread. In a multithread application, each thread +must use its own JIT stack. For more details, see the +pcrejit +page. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_compile.html b/doc/html/pcre_compile.html new file mode 100644 index 0000000..95b4bec --- /dev/null +++ b/doc/html/pcre_compile.html @@ -0,0 +1,111 @@ + + +pcre_compile specification + + +

pcre_compile man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+pcre *pcre_compile(const char *pattern, int options, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +

+
+DESCRIPTION +
+

+This function compiles a regular expression into an internal form. It is the +same as pcre[16|32]_compile2(), except for the absence of the +errorcodeptr argument. Its arguments are: +

+  pattern       A zero-terminated string containing the
+                  regular expression to be compiled
+  options       Zero or more option bits
+  errptr        Where to put an error message
+  erroffset     Offset in pattern where error was found
+  tableptr      Pointer to character tables, or NULL to
+                  use the built-in default
+
+The option bits are: +
+  PCRE_ANCHORED           Force pattern anchoring
+  PCRE_AUTO_CALLOUT       Compile automatic callouts
+  PCRE_BSR_ANYCRLF        \R matches only CR, LF, or CRLF
+  PCRE_BSR_UNICODE        \R matches all Unicode line endings
+  PCRE_CASELESS           Do caseless matching
+  PCRE_DOLLAR_ENDONLY     $ not to match newline at end
+  PCRE_DOTALL             . matches anything including NL
+  PCRE_DUPNAMES           Allow duplicate names for subpatterns
+  PCRE_EXTENDED           Ignore white space and # comments
+  PCRE_EXTRA              PCRE extra features
+                            (not much use currently)
+  PCRE_FIRSTLINE          Force matching to be before newline
+  PCRE_JAVASCRIPT_COMPAT  JavaScript compatibility
+  PCRE_MULTILINE          ^ and $ match newlines within data
+  PCRE_NEVER_UTF          Lock out UTF, e.g. via (*UTF)
+  PCRE_NEWLINE_ANY        Recognize any Unicode newline sequence
+  PCRE_NEWLINE_ANYCRLF    Recognize CR, LF, and CRLF as newline
+                            sequences
+  PCRE_NEWLINE_CR         Set CR as the newline sequence
+  PCRE_NEWLINE_CRLF       Set CRLF as the newline sequence
+  PCRE_NEWLINE_LF         Set LF as the newline sequence
+  PCRE_NO_AUTO_CAPTURE    Disable numbered capturing paren-
+                            theses (named ones available)
+  PCRE_NO_AUTO_POSSESS    Disable auto-possessification
+  PCRE_NO_START_OPTIMIZE  Disable match-time start optimizations
+  PCRE_NO_UTF16_CHECK     Do not check the pattern for UTF-16
+                            validity (only relevant if
+                            PCRE_UTF16 is set)
+  PCRE_NO_UTF32_CHECK     Do not check the pattern for UTF-32
+                            validity (only relevant if
+                            PCRE_UTF32 is set)
+  PCRE_NO_UTF8_CHECK      Do not check the pattern for UTF-8
+                            validity (only relevant if
+                            PCRE_UTF8 is set)
+  PCRE_UCP                Use Unicode properties for \d, \w, etc.
+  PCRE_UNGREEDY           Invert greediness of quantifiers
+  PCRE_UTF16              Run in pcre16_compile() UTF-16 mode
+  PCRE_UTF32              Run in pcre32_compile() UTF-32 mode
+  PCRE_UTF8               Run in pcre_compile() UTF-8 mode
+
+PCRE must be built with UTF support in order to use PCRE_UTF8/16/32 and +PCRE_NO_UTF8/16/32_CHECK, and with UCP support if PCRE_UCP is used. +

+

+The yield of the function is a pointer to a private data structure that +contains the compiled pattern, or NULL if an error was detected. Note that +compiling regular expressions with one version of PCRE for use with a different +version is not guaranteed to work and may cause crashes. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_compile2.html b/doc/html/pcre_compile2.html new file mode 100644 index 0000000..9cd56a2 --- /dev/null +++ b/doc/html/pcre_compile2.html @@ -0,0 +1,115 @@ + + +pcre_compile2 specification + + +

pcre_compile2 man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+pcre *pcre_compile2(const char *pattern, int options, + int *errorcodeptr, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options, + int *errorcodeptr, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options, +" int *errorcodeptr,£ + const char **errptr, int *erroffset, + const unsigned char *tableptr); +

+
+DESCRIPTION +
+

+This function compiles a regular expression into an internal form. It is the +same as pcre[16|32]_compile(), except for the addition of the +errorcodeptr argument. The arguments are: +

+  pattern       A zero-terminated string containing the
+                  regular expression to be compiled
+  options       Zero or more option bits
+  errorcodeptr  Where to put an error code
+  errptr        Where to put an error message
+  erroffset     Offset in pattern where error was found
+  tableptr      Pointer to character tables, or NULL to
+                  use the built-in default
+
+The option bits are: +
+  PCRE_ANCHORED           Force pattern anchoring
+  PCRE_AUTO_CALLOUT       Compile automatic callouts
+  PCRE_BSR_ANYCRLF        \R matches only CR, LF, or CRLF
+  PCRE_BSR_UNICODE        \R matches all Unicode line endings
+  PCRE_CASELESS           Do caseless matching
+  PCRE_DOLLAR_ENDONLY     $ not to match newline at end
+  PCRE_DOTALL             . matches anything including NL
+  PCRE_DUPNAMES           Allow duplicate names for subpatterns
+  PCRE_EXTENDED           Ignore white space and # comments
+  PCRE_EXTRA              PCRE extra features
+                            (not much use currently)
+  PCRE_FIRSTLINE          Force matching to be before newline
+  PCRE_JAVASCRIPT_COMPAT  JavaScript compatibility
+  PCRE_MULTILINE          ^ and $ match newlines within data
+  PCRE_NEVER_UTF          Lock out UTF, e.g. via (*UTF)
+  PCRE_NEWLINE_ANY        Recognize any Unicode newline sequence
+  PCRE_NEWLINE_ANYCRLF    Recognize CR, LF, and CRLF as newline
+                            sequences
+  PCRE_NEWLINE_CR         Set CR as the newline sequence
+  PCRE_NEWLINE_CRLF       Set CRLF as the newline sequence
+  PCRE_NEWLINE_LF         Set LF as the newline sequence
+  PCRE_NO_AUTO_CAPTURE    Disable numbered capturing paren-
+                            theses (named ones available)
+  PCRE_NO_AUTO_POSSESS    Disable auto-possessification
+  PCRE_NO_START_OPTIMIZE  Disable match-time start optimizations
+  PCRE_NO_UTF16_CHECK     Do not check the pattern for UTF-16
+                            validity (only relevant if
+                            PCRE_UTF16 is set)
+  PCRE_NO_UTF32_CHECK     Do not check the pattern for UTF-32
+                            validity (only relevant if
+                            PCRE_UTF32 is set)
+  PCRE_NO_UTF8_CHECK      Do not check the pattern for UTF-8
+                            validity (only relevant if
+                            PCRE_UTF8 is set)
+  PCRE_UCP                Use Unicode properties for \d, \w, etc.
+  PCRE_UNGREEDY           Invert greediness of quantifiers
+  PCRE_UTF16              Run pcre16_compile() in UTF-16 mode
+  PCRE_UTF32              Run pcre32_compile() in UTF-32 mode
+  PCRE_UTF8               Run pcre_compile() in UTF-8 mode
+
+PCRE must be built with UTF support in order to use PCRE_UTF8/16/32 and +PCRE_NO_UTF8/16/32_CHECK, and with UCP support if PCRE_UCP is used. +

+

+The yield of the function is a pointer to a private data structure that +contains the compiled pattern, or NULL if an error was detected. Note that +compiling regular expressions with one version of PCRE for use with a different +version is not guaranteed to work and may cause crashes. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_config.html b/doc/html/pcre_config.html new file mode 100644 index 0000000..bcdcdde --- /dev/null +++ b/doc/html/pcre_config.html @@ -0,0 +1,92 @@ + + +pcre_config specification + + +

pcre_config man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_config(int what, void *where); +

+

+int pcre16_config(int what, void *where); +

+

+int pcre32_config(int what, void *where); +

+
+DESCRIPTION +
+

+This function makes it possible for a client program to find out which optional +features are available in the version of the PCRE library it is using. The +arguments are as follows: +

+  what     A code specifying what information is required
+  where    Points to where to put the data
+
+The where argument must point to an integer variable, except for +PCRE_CONFIG_MATCH_LIMIT and PCRE_CONFIG_MATCH_LIMIT_RECURSION, when it must +point to an unsigned long integer. The available codes are: +
+  PCRE_CONFIG_JIT           Availability of just-in-time compiler
+                              support (1=yes 0=no)
+  PCRE_CONFIG_JITTARGET     String containing information about the
+                              target architecture for the JIT compiler,
+                              or NULL if there is no JIT support
+  PCRE_CONFIG_LINK_SIZE     Internal link size: 2, 3, or 4
+  PCRE_CONFIG_PARENS_LIMIT  Parentheses nesting limit
+  PCRE_CONFIG_MATCH_LIMIT   Internal resource limit
+  PCRE_CONFIG_MATCH_LIMIT_RECURSION
+                            Internal recursion depth limit
+  PCRE_CONFIG_NEWLINE       Value of the default newline sequence:
+                                13 (0x000d)    for CR
+                                10 (0x000a)    for LF
+                              3338 (0x0d0a)    for CRLF
+                                -2             for ANYCRLF
+                                -1             for ANY
+  PCRE_CONFIG_BSR           Indicates what \R matches by default:
+                                 0             all Unicode line endings
+                                 1             CR, LF, or CRLF only
+  PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
+                            Threshold of return slots, above which
+                              malloc() is used by the POSIX API
+  PCRE_CONFIG_STACKRECURSE  Recursion implementation (1=stack 0=heap)
+  PCRE_CONFIG_UTF16         Availability of UTF-16 support (1=yes
+                               0=no); option for pcre16_config()
+  PCRE_CONFIG_UTF32         Availability of UTF-32 support (1=yes
+                               0=no); option for pcre32_config()
+  PCRE_CONFIG_UTF8          Availability of UTF-8 support (1=yes 0=no);
+                              option for pcre_config()
+  PCRE_CONFIG_UNICODE_PROPERTIES
+                            Availability of Unicode property support
+                              (1=yes 0=no)
+
+The function yields 0 on success or PCRE_ERROR_BADOPTION otherwise. That error +is also given if PCRE_CONFIG_UTF16 or PCRE_CONFIG_UTF32 is passed to +pcre_config(), if PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF32 is passed to +pcre16_config(), or if PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF16 is passed to +pcre32_config(). +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_copy_named_substring.html b/doc/html/pcre_copy_named_substring.html new file mode 100644 index 0000000..77b4804 --- /dev/null +++ b/doc/html/pcre_copy_named_substring.html @@ -0,0 +1,65 @@ + + +pcre_copy_named_substring specification + + +

pcre_copy_named_substring man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_copy_named_substring(const pcre *code, + const char *subject, int *ovector, + int stringcount, const char *stringname, + char *buffer, int buffersize); +
+
+int pcre16_copy_named_substring(const pcre16 *code, + PCRE_SPTR16 subject, int *ovector, + int stringcount, PCRE_SPTR16 stringname, + PCRE_UCHAR16 *buffer, int buffersize); +
+
+int pcre32_copy_named_substring(const pcre32 *code, + PCRE_SPTR32 subject, int *ovector, + int stringcount, PCRE_SPTR32 stringname, + PCRE_UCHAR32 *buffer, int buffersize); +

+
+DESCRIPTION +
+

+This is a convenience function for extracting a captured substring, identified +by name, into a given buffer. The arguments are: +

+  code          Pattern that was successfully matched
+  subject       Subject that has been successfully matched
+  ovector       Offset vector that pcre[16|32]_exec() used
+  stringcount   Value returned by pcre[16|32]_exec()
+  stringname    Name of the required substring
+  buffer        Buffer to receive the string
+  buffersize    Size of buffer
+
+The yield is the length of the substring, PCRE_ERROR_NOMEMORY if the buffer was +too small, or PCRE_ERROR_NOSUBSTRING if the string name is invalid. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_copy_substring.html b/doc/html/pcre_copy_substring.html new file mode 100644 index 0000000..ecaebe8 --- /dev/null +++ b/doc/html/pcre_copy_substring.html @@ -0,0 +1,61 @@ + + +pcre_copy_substring specification + + +

pcre_copy_substring man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_copy_substring(const char *subject, int *ovector, + int stringcount, int stringnumber, char *buffer, + int buffersize); +
+
+int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector, + int stringcount, int stringnumber, PCRE_UCHAR16 *buffer, + int buffersize); +
+
+int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector, + int stringcount, int stringnumber, PCRE_UCHAR32 *buffer, + int buffersize); +

+
+DESCRIPTION +
+

+This is a convenience function for extracting a captured substring into a given +buffer. The arguments are: +

+  subject       Subject that has been successfully matched
+  ovector       Offset vector that pcre[16|32]_exec() used
+  stringcount   Value returned by pcre[16|32]_exec()
+  stringnumber  Number of the required substring
+  buffer        Buffer to receive the string
+  buffersize    Size of buffer
+
+The yield is the length of the string, PCRE_ERROR_NOMEMORY if the buffer was +too small, or PCRE_ERROR_NOSUBSTRING if the string number is invalid. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_dfa_exec.html b/doc/html/pcre_dfa_exec.html new file mode 100644 index 0000000..5fff6a7 --- /dev/null +++ b/doc/html/pcre_dfa_exec.html @@ -0,0 +1,129 @@ + + +pcre_dfa_exec specification + + +

pcre_dfa_exec man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_dfa_exec(const pcre *code, const pcre_extra *extra, + const char *subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + int *workspace, int wscount); +
+
+int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra, + PCRE_SPTR16 subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + int *workspace, int wscount); +
+
+int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra, + PCRE_SPTR32 subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + int *workspace, int wscount); +

+
+DESCRIPTION +
+

+This function matches a compiled regular expression against a given subject +string, using an alternative matching algorithm that scans the subject string +just once (not Perl-compatible). Note that the main, Perl-compatible, +matching function is pcre[16|32]_exec(). The arguments for this function +are: +

+  code         Points to the compiled pattern
+  extra        Points to an associated pcre[16|32]_extra structure,
+                 or is NULL
+  subject      Points to the subject string
+  length       Length of the subject string
+  startoffset  Offset in the subject at which to start matching
+  options      Option bits
+  ovector      Points to a vector of ints for result offsets
+  ovecsize     Number of elements in the vector
+  workspace    Points to a vector of ints used as working space
+  wscount      Number of elements in the vector
+
+The units for length and startoffset are bytes for +pcre_exec(), 16-bit data items for pcre16_exec(), and 32-bit items +for pcre32_exec(). The options are: +
+  PCRE_ANCHORED          Match only at the first position
+  PCRE_BSR_ANYCRLF       \R matches only CR, LF, or CRLF
+  PCRE_BSR_UNICODE       \R matches all Unicode line endings
+  PCRE_NEWLINE_ANY       Recognize any Unicode newline sequence
+  PCRE_NEWLINE_ANYCRLF   Recognize CR, LF, & CRLF as newline sequences
+  PCRE_NEWLINE_CR        Recognize CR as the only newline sequence
+  PCRE_NEWLINE_CRLF      Recognize CRLF as the only newline sequence
+  PCRE_NEWLINE_LF        Recognize LF as the only newline sequence
+  PCRE_NOTBOL            Subject is not the beginning of a line
+  PCRE_NOTEOL            Subject is not the end of a line
+  PCRE_NOTEMPTY          An empty string is not a valid match
+  PCRE_NOTEMPTY_ATSTART  An empty string at the start of the subject
+                           is not a valid match
+  PCRE_NO_START_OPTIMIZE Do not do "start-match" optimizations
+  PCRE_NO_UTF16_CHECK    Do not check the subject for UTF-16
+                           validity (only relevant if PCRE_UTF16
+                           was set at compile time)
+  PCRE_NO_UTF32_CHECK    Do not check the subject for UTF-32
+                           validity (only relevant if PCRE_UTF32
+                           was set at compile time)
+  PCRE_NO_UTF8_CHECK     Do not check the subject for UTF-8
+                           validity (only relevant if PCRE_UTF8
+                           was set at compile time)
+  PCRE_PARTIAL           ) Return PCRE_ERROR_PARTIAL for a partial
+  PCRE_PARTIAL_SOFT      )   match if no full matches are found
+  PCRE_PARTIAL_HARD      Return PCRE_ERROR_PARTIAL for a partial match
+                           even if there is a full match as well
+  PCRE_DFA_SHORTEST      Return only the shortest match
+  PCRE_DFA_RESTART       Restart after a partial match
+
+There are restrictions on what may appear in a pattern when using this matching +function. Details are given in the +pcrematching +documentation. For details of partial matching, see the +pcrepartial +page. +

+

+A pcre[16|32]_extra structure contains the following fields: +

+  flags            Bits indicating which fields are set
+  study_data       Opaque data from pcre[16|32]_study()
+  match_limit      Limit on internal resource use
+  match_limit_recursion  Limit on internal recursion depth
+  callout_data     Opaque data passed back to callouts
+  tables           Points to character tables or is NULL
+  mark             For passing back a *MARK pointer
+  executable_jit   Opaque data from JIT compilation
+
+The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT, +PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA, +PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT. For this +matching function, the match_limit and match_limit_recursion fields +are not used, and must not be set. The PCRE_EXTRA_EXECUTABLE_JIT flag and +the corresponding variable are ignored. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_exec.html b/doc/html/pcre_exec.html new file mode 100644 index 0000000..18e1a13 --- /dev/null +++ b/doc/html/pcre_exec.html @@ -0,0 +1,111 @@ + + +pcre_exec specification + + +

pcre_exec man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_exec(const pcre *code, const pcre_extra *extra, + const char *subject, int length, int startoffset, + int options, int *ovector, int ovecsize); +
+
+int pcre16_exec(const pcre16 *code, const pcre16_extra *extra, + PCRE_SPTR16 subject, int length, int startoffset, + int options, int *ovector, int ovecsize); +
+
+int pcre32_exec(const pcre32 *code, const pcre32_extra *extra, + PCRE_SPTR32 subject, int length, int startoffset, + int options, int *ovector, int ovecsize); +

+
+DESCRIPTION +
+

+This function matches a compiled regular expression against a given subject +string, using a matching algorithm that is similar to Perl's. It returns +offsets to captured substrings. Its arguments are: +

+  code         Points to the compiled pattern
+  extra        Points to an associated pcre[16|32]_extra structure,
+                 or is NULL
+  subject      Points to the subject string
+  length       Length of the subject string
+  startoffset  Offset in the subject at which to start matching
+  options      Option bits
+  ovector      Points to a vector of ints for result offsets
+  ovecsize     Number of elements in the vector (a multiple of 3)
+
+The units for length and startoffset are bytes for +pcre_exec(), 16-bit data items for pcre16_exec(), and 32-bit items +for pcre32_exec(). The options are: +
+  PCRE_ANCHORED          Match only at the first position
+  PCRE_BSR_ANYCRLF       \R matches only CR, LF, or CRLF
+  PCRE_BSR_UNICODE       \R matches all Unicode line endings
+  PCRE_NEWLINE_ANY       Recognize any Unicode newline sequence
+  PCRE_NEWLINE_ANYCRLF   Recognize CR, LF, & CRLF as newline sequences
+  PCRE_NEWLINE_CR        Recognize CR as the only newline sequence
+  PCRE_NEWLINE_CRLF      Recognize CRLF as the only newline sequence
+  PCRE_NEWLINE_LF        Recognize LF as the only newline sequence
+  PCRE_NOTBOL            Subject string is not the beginning of a line
+  PCRE_NOTEOL            Subject string is not the end of a line
+  PCRE_NOTEMPTY          An empty string is not a valid match
+  PCRE_NOTEMPTY_ATSTART  An empty string at the start of the subject
+                           is not a valid match
+  PCRE_NO_START_OPTIMIZE Do not do "start-match" optimizations
+  PCRE_NO_UTF16_CHECK    Do not check the subject for UTF-16
+                           validity (only relevant if PCRE_UTF16
+                           was set at compile time)
+  PCRE_NO_UTF32_CHECK    Do not check the subject for UTF-32
+                           validity (only relevant if PCRE_UTF32
+                           was set at compile time)
+  PCRE_NO_UTF8_CHECK     Do not check the subject for UTF-8
+                           validity (only relevant if PCRE_UTF8
+                           was set at compile time)
+  PCRE_PARTIAL           ) Return PCRE_ERROR_PARTIAL for a partial
+  PCRE_PARTIAL_SOFT      )   match if no full matches are found
+  PCRE_PARTIAL_HARD      Return PCRE_ERROR_PARTIAL for a partial match
+                           if that is found before a full match
+
+For details of partial matching, see the +pcrepartial +page. A pcre_extra structure contains the following fields: +
+  flags            Bits indicating which fields are set
+  study_data       Opaque data from pcre[16|32]_study()
+  match_limit      Limit on internal resource use
+  match_limit_recursion  Limit on internal recursion depth
+  callout_data     Opaque data passed back to callouts
+  tables           Points to character tables or is NULL
+  mark             For passing back a *MARK pointer
+  executable_jit   Opaque data from JIT compilation
+
+The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT, +PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA, +PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_free_study.html b/doc/html/pcre_free_study.html new file mode 100644 index 0000000..7f9e10e --- /dev/null +++ b/doc/html/pcre_free_study.html @@ -0,0 +1,46 @@ + + +pcre_free_study specification + + +

pcre_free_study man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+void pcre_free_study(pcre_extra *extra); +

+

+void pcre16_free_study(pcre16_extra *extra); +

+

+void pcre32_free_study(pcre32_extra *extra); +

+
+DESCRIPTION +
+

+This function is used to free the memory used for the data generated by a call +to pcre[16|32]_study() when it is no longer needed. The argument must be the +result of such a call. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_free_substring.html b/doc/html/pcre_free_substring.html new file mode 100644 index 0000000..1fe6610 --- /dev/null +++ b/doc/html/pcre_free_substring.html @@ -0,0 +1,46 @@ + + +pcre_free_substring specification + + +

pcre_free_substring man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+void pcre_free_substring(const char *stringptr); +

+

+void pcre16_free_substring(PCRE_SPTR16 stringptr); +

+

+void pcre32_free_substring(PCRE_SPTR32 stringptr); +

+
+DESCRIPTION +
+

+This is a convenience function for freeing the store obtained by a previous +call to pcre[16|32]_get_substring() or pcre[16|32]_get_named_substring(). +Its only argument is a pointer to the string. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_free_substring_list.html b/doc/html/pcre_free_substring_list.html new file mode 100644 index 0000000..c086178 --- /dev/null +++ b/doc/html/pcre_free_substring_list.html @@ -0,0 +1,46 @@ + + +pcre_free_substring_list specification + + +

pcre_free_substring_list man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+void pcre_free_substring_list(const char **stringptr); +

+

+void pcre16_free_substring_list(PCRE_SPTR16 *stringptr); +

+

+void pcre32_free_substring_list(PCRE_SPTR32 *stringptr); +

+
+DESCRIPTION +
+

+This is a convenience function for freeing the store obtained by a previous +call to pcre[16|32]_get_substring_list(). Its only argument is a pointer to +the list of string pointers. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_fullinfo.html b/doc/html/pcre_fullinfo.html new file mode 100644 index 0000000..b88fc11 --- /dev/null +++ b/doc/html/pcre_fullinfo.html @@ -0,0 +1,108 @@ + + +pcre_fullinfo specification + + +

pcre_fullinfo man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_fullinfo(const pcre *code, const pcre_extra *extra, + int what, void *where); +
+
+int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra, + int what, void *where); +
+
+int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra, + int what, void *where); +

+
+DESCRIPTION +
+

+This function returns information about a compiled pattern. Its arguments are: +

+  code                      Compiled regular expression
+  extra                     Result of pcre[16|32]_study() or NULL
+  what                      What information is required
+  where                     Where to put the information
+
+The following information is available: +
+  PCRE_INFO_BACKREFMAX      Number of highest back reference
+  PCRE_INFO_CAPTURECOUNT    Number of capturing subpatterns
+  PCRE_INFO_DEFAULT_TABLES  Pointer to default tables
+  PCRE_INFO_FIRSTBYTE       Fixed first data unit for a match, or
+                              -1 for start of string
+                                 or after newline, or
+                              -2 otherwise
+  PCRE_INFO_FIRSTTABLE      Table of first data units (after studying)
+  PCRE_INFO_HASCRORLF       Return 1 if explicit CR or LF matches exist
+  PCRE_INFO_JCHANGED        Return 1 if (?J) or (?-J) was used
+  PCRE_INFO_JIT             Return 1 after successful JIT compilation
+  PCRE_INFO_JITSIZE         Size of JIT compiled code
+  PCRE_INFO_LASTLITERAL     Literal last data unit required
+  PCRE_INFO_MINLENGTH       Lower bound length of matching strings
+  PCRE_INFO_NAMECOUNT       Number of named subpatterns
+  PCRE_INFO_NAMEENTRYSIZE   Size of name table entry
+  PCRE_INFO_NAMETABLE       Pointer to name table
+  PCRE_INFO_OKPARTIAL       Return 1 if partial matching can be tried
+                              (always returns 1 after release 8.00)
+  PCRE_INFO_OPTIONS         Option bits used for compilation
+  PCRE_INFO_SIZE            Size of compiled pattern
+  PCRE_INFO_STUDYSIZE       Size of study data
+  PCRE_INFO_FIRSTCHARACTER      Fixed first data unit for a match
+  PCRE_INFO_FIRSTCHARACTERFLAGS Returns
+                                  1 if there is a first data character set, which can
+                                    then be retrieved using PCRE_INFO_FIRSTCHARACTER,
+                                  2 if the first character is at the start of the data
+                                    string or after a newline, and
+                                  0 otherwise
+  PCRE_INFO_REQUIREDCHAR      Literal last data unit required
+  PCRE_INFO_REQUIREDCHARFLAGS Returns 1 if the last data character is set (which can then
+                              be retrieved using PCRE_INFO_REQUIREDCHAR); 0 otherwise
+
+The where argument must point to an integer variable, except for the +following what values: +
+  PCRE_INFO_DEFAULT_TABLES  const unsigned char *
+  PCRE_INFO_FIRSTTABLE      const unsigned char *
+  PCRE_INFO_NAMETABLE       PCRE_SPTR16           (16-bit library)
+  PCRE_INFO_NAMETABLE       PCRE_SPTR32           (32-bit library)
+  PCRE_INFO_NAMETABLE       const unsigned char * (8-bit library)
+  PCRE_INFO_OPTIONS         unsigned long int
+  PCRE_INFO_SIZE            size_t
+  PCRE_INFO_FIRSTCHARACTER  uint32_t
+  PCRE_INFO_REQUIREDCHAR    uint32_t
+
+The yield of the function is zero on success or: +
+  PCRE_ERROR_NULL           the argument code was NULL
+                            the argument where was NULL
+  PCRE_ERROR_BADMAGIC       the "magic number" was not found
+  PCRE_ERROR_BADOPTION      the value of what was invalid
+
+

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_get_named_substring.html b/doc/html/pcre_get_named_substring.html new file mode 100644 index 0000000..72924d9 --- /dev/null +++ b/doc/html/pcre_get_named_substring.html @@ -0,0 +1,68 @@ + + +pcre_get_named_substring specification + + +

pcre_get_named_substring man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_get_named_substring(const pcre *code, + const char *subject, int *ovector, + int stringcount, const char *stringname, + const char **stringptr); +
+
+int pcre16_get_named_substring(const pcre16 *code, + PCRE_SPTR16 subject, int *ovector, + int stringcount, PCRE_SPTR16 stringname, + PCRE_SPTR16 *stringptr); +
+
+int pcre32_get_named_substring(const pcre32 *code, + PCRE_SPTR32 subject, int *ovector, + int stringcount, PCRE_SPTR32 stringname, + PCRE_SPTR32 *stringptr); +

+
+DESCRIPTION +
+

+This is a convenience function for extracting a captured substring by name. The +arguments are: +

+  code          Compiled pattern
+  subject       Subject that has been successfully matched
+  ovector       Offset vector that pcre[16|32]_exec() used
+  stringcount   Value returned by pcre[16|32]_exec()
+  stringname    Name of the required substring
+  stringptr     Where to put the string pointer
+
+The memory in which the substring is placed is obtained by calling +pcre[16|32]_malloc(). The convenience function +pcre[16|32]_free_substring() can be used to free it when it is no longer +needed. The yield of the function is the length of the extracted substring, +PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or +PCRE_ERROR_NOSUBSTRING if the string name is invalid. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_get_stringnumber.html b/doc/html/pcre_get_stringnumber.html new file mode 100644 index 0000000..7324d78 --- /dev/null +++ b/doc/html/pcre_get_stringnumber.html @@ -0,0 +1,57 @@ + + +pcre_get_stringnumber specification + + +

pcre_get_stringnumber man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_get_stringnumber(const pcre *code, + const char *name); +
+
+int pcre16_get_stringnumber(const pcre16 *code, + PCRE_SPTR16 name); +
+
+int pcre32_get_stringnumber(const pcre32 *code, + PCRE_SPTR32 name); +

+
+DESCRIPTION +
+

+This convenience function finds the number of a named substring capturing +parenthesis in a compiled pattern. Its arguments are: +

+  code    Compiled regular expression
+  name    Name whose number is required
+
+The yield of the function is the number of the parenthesis if the name is +found, or PCRE_ERROR_NOSUBSTRING otherwise. When duplicate names are allowed +(PCRE_DUPNAMES is set), it is not defined which of the numbers is returned by +pcre[16|32]_get_stringnumber(). You can obtain the complete list by calling +pcre[16|32]_get_stringtable_entries(). +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_get_stringtable_entries.html b/doc/html/pcre_get_stringtable_entries.html new file mode 100644 index 0000000..7990679 --- /dev/null +++ b/doc/html/pcre_get_stringtable_entries.html @@ -0,0 +1,60 @@ + + +pcre_get_stringtable_entries specification + + +

pcre_get_stringtable_entries man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_get_stringtable_entries(const pcre *code, + const char *name, char **first, char **last); +
+
+int pcre16_get_stringtable_entries(const pcre16 *code, + PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last); +
+
+int pcre32_get_stringtable_entries(const pcre32 *code, + PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last); +

+
+DESCRIPTION +
+

+This convenience function finds, for a compiled pattern, the first and last +entries for a given name in the table that translates capturing parenthesis +names into numbers. When names are required to be unique (PCRE_DUPNAMES is +not set), it is usually easier to use pcre[16|32]_get_stringnumber() +instead. +

+  code    Compiled regular expression
+  name    Name whose entries required
+  first   Where to return a pointer to the first entry
+  last    Where to return a pointer to the last entry
+
+The yield of the function is the length of each entry, or +PCRE_ERROR_NOSUBSTRING if none are found. +

+

+There is a complete description of the PCRE native API, including the format of +the table entries, in the +pcreapi +page, and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_get_substring.html b/doc/html/pcre_get_substring.html new file mode 100644 index 0000000..1a8e4f5 --- /dev/null +++ b/doc/html/pcre_get_substring.html @@ -0,0 +1,64 @@ + + +pcre_get_substring specification + + +

pcre_get_substring man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_get_substring(const char *subject, int *ovector, + int stringcount, int stringnumber, + const char **stringptr); +
+
+int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector, + int stringcount, int stringnumber, + PCRE_SPTR16 *stringptr); +
+
+int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector, + int stringcount, int stringnumber, + PCRE_SPTR32 *stringptr); +

+
+DESCRIPTION +
+

+This is a convenience function for extracting a captured substring. The +arguments are: +

+  subject       Subject that has been successfully matched
+  ovector       Offset vector that pcre[16|32]_exec() used
+  stringcount   Value returned by pcre[16|32]_exec()
+  stringnumber  Number of the required substring
+  stringptr     Where to put the string pointer
+
+The memory in which the substring is placed is obtained by calling +pcre[16|32]_malloc(). The convenience function +pcre[16|32]_free_substring() can be used to free it when it is no longer +needed. The yield of the function is the length of the substring, +PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or +PCRE_ERROR_NOSUBSTRING if the string number is invalid. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_get_substring_list.html b/doc/html/pcre_get_substring_list.html new file mode 100644 index 0000000..7e8c6bc --- /dev/null +++ b/doc/html/pcre_get_substring_list.html @@ -0,0 +1,61 @@ + + +pcre_get_substring_list specification + + +

pcre_get_substring_list man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_get_substring_list(const char *subject, + int *ovector, int stringcount, const char ***listptr); +
+
+int pcre16_get_substring_list(PCRE_SPTR16 subject, + int *ovector, int stringcount, PCRE_SPTR16 **listptr); +
+
+int pcre32_get_substring_list(PCRE_SPTR32 subject, + int *ovector, int stringcount, PCRE_SPTR32 **listptr); +

+
+DESCRIPTION +
+

+This is a convenience function for extracting a list of all the captured +substrings. The arguments are: +

+  subject       Subject that has been successfully matched
+  ovector       Offset vector that pcre[16|32]_exec used
+  stringcount   Value returned by pcre[16|32]_exec
+  listptr       Where to put a pointer to the list
+
+The memory in which the substrings and the list are placed is obtained by +calling pcre[16|32]_malloc(). The convenience function +pcre[16|32]_free_substring_list() can be used to free it when it is no +longer needed. A pointer to a list of pointers is put in the variable whose +address is in listptr. The list is terminated by a NULL pointer. The +yield of the function is zero on success or PCRE_ERROR_NOMEMORY if sufficient +memory could not be obtained. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_jit_exec.html b/doc/html/pcre_jit_exec.html new file mode 100644 index 0000000..4ebb0cb --- /dev/null +++ b/doc/html/pcre_jit_exec.html @@ -0,0 +1,108 @@ + + +pcre_jit_exec specification + + +

pcre_jit_exec man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_jit_exec(const pcre *code, const pcre_extra *extra, + const char *subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + pcre_jit_stack *jstack); +
+
+int pcre16_jit_exec(const pcre16 *code, const pcre16_extra *extra, + PCRE_SPTR16 subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + pcre_jit_stack *jstack); +
+
+int pcre32_jit_exec(const pcre32 *code, const pcre32_extra *extra, + PCRE_SPTR32 subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + pcre_jit_stack *jstack); +

+
+DESCRIPTION +
+

+This function matches a compiled regular expression that has been successfully +studied with one of the JIT options against a given subject string, using a +matching algorithm that is similar to Perl's. It is a "fast path" interface to +JIT, and it bypasses some of the sanity checks that pcre_exec() applies. +It returns offsets to captured substrings. Its arguments are: +

+  code         Points to the compiled pattern
+  extra        Points to an associated pcre[16|32]_extra structure,
+                 or is NULL
+  subject      Points to the subject string
+  length       Length of the subject string, in bytes
+  startoffset  Offset in bytes in the subject at which to
+                 start matching
+  options      Option bits
+  ovector      Points to a vector of ints for result offsets
+  ovecsize     Number of elements in the vector (a multiple of 3)
+  jstack       Pointer to a JIT stack
+
+The allowed options are: +
+  PCRE_NOTBOL            Subject string is not the beginning of a line
+  PCRE_NOTEOL            Subject string is not the end of a line
+  PCRE_NOTEMPTY          An empty string is not a valid match
+  PCRE_NOTEMPTY_ATSTART  An empty string at the start of the subject
+                           is not a valid match
+  PCRE_NO_UTF16_CHECK    Do not check the subject for UTF-16
+                           validity (only relevant if PCRE_UTF16
+                           was set at compile time)
+  PCRE_NO_UTF32_CHECK    Do not check the subject for UTF-32
+                           validity (only relevant if PCRE_UTF32
+                           was set at compile time)
+  PCRE_NO_UTF8_CHECK     Do not check the subject for UTF-8
+                           validity (only relevant if PCRE_UTF8
+                           was set at compile time)
+  PCRE_PARTIAL           ) Return PCRE_ERROR_PARTIAL for a partial
+  PCRE_PARTIAL_SOFT      )   match if no full matches are found
+  PCRE_PARTIAL_HARD      Return PCRE_ERROR_PARTIAL for a partial match
+                           if that is found before a full match
+
+However, the PCRE_NO_UTF[8|16|32]_CHECK options have no effect, as this check +is never applied. For details of partial matching, see the +pcrepartial +page. A pcre_extra structure contains the following fields: +
+  flags            Bits indicating which fields are set
+  study_data       Opaque data from pcre[16|32]_study()
+  match_limit      Limit on internal resource use
+  match_limit_recursion  Limit on internal recursion depth
+  callout_data     Opaque data passed back to callouts
+  tables           Points to character tables or is NULL
+  mark             For passing back a *MARK pointer
+  executable_jit   Opaque data from JIT compilation
+
+The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT, +PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA, +PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the JIT API in the +pcrejit +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_jit_stack_alloc.html b/doc/html/pcre_jit_stack_alloc.html new file mode 100644 index 0000000..23ba450 --- /dev/null +++ b/doc/html/pcre_jit_stack_alloc.html @@ -0,0 +1,55 @@ + + +pcre_jit_stack_alloc specification + + +

pcre_jit_stack_alloc man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+pcre_jit_stack *pcre_jit_stack_alloc(int startsize, + int maxsize); +
+
+pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, + int maxsize); +
+
+pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, + int maxsize); +

+
+DESCRIPTION +
+

+This function is used to create a stack for use by the code compiled by the JIT +optimization of pcre[16|32]_study(). The arguments are a starting size for +the stack, and a maximum size to which it is allowed to grow. The result can be +passed to the JIT run-time code by pcre[16|32]_assign_jit_stack(), or that +function can set up a callback for obtaining a stack. A maximum stack size of +512K to 1M should be more than enough for any pattern. For more details, see +the +pcrejit +page. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_jit_stack_free.html b/doc/html/pcre_jit_stack_free.html new file mode 100644 index 0000000..8bd06e4 --- /dev/null +++ b/doc/html/pcre_jit_stack_free.html @@ -0,0 +1,48 @@ + + +pcre_jit_stack_free specification + + +

pcre_jit_stack_free man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+void pcre_jit_stack_free(pcre_jit_stack *stack); +

+

+void pcre16_jit_stack_free(pcre16_jit_stack *stack); +

+

+void pcre32_jit_stack_free(pcre32_jit_stack *stack); +

+
+DESCRIPTION +
+

+This function is used to free a JIT stack that was created by +pcre[16|32]_jit_stack_alloc() when it is no longer needed. For more details, +see the +pcrejit +page. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_maketables.html b/doc/html/pcre_maketables.html new file mode 100644 index 0000000..3a7b5eb --- /dev/null +++ b/doc/html/pcre_maketables.html @@ -0,0 +1,48 @@ + + +pcre_maketables specification + + +

pcre_maketables man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+const unsigned char *pcre_maketables(void); +

+

+const unsigned char *pcre16_maketables(void); +

+

+const unsigned char *pcre32_maketables(void); +

+
+DESCRIPTION +
+

+This function builds a set of character tables for character values less than +256. These can be passed to pcre[16|32]_compile() to override PCRE's +internal, built-in tables (which were made by pcre[16|32]_maketables() when +PCRE was compiled). You might want to do this if you are using a non-standard +locale. The function yields a pointer to the tables. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_pattern_to_host_byte_order.html b/doc/html/pcre_pattern_to_host_byte_order.html new file mode 100644 index 0000000..1b1c803 --- /dev/null +++ b/doc/html/pcre_pattern_to_host_byte_order.html @@ -0,0 +1,58 @@ + + +pcre_pattern_to_host_byte_order specification + + +

pcre_pattern_to_host_byte_order man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_pattern_to_host_byte_order(pcre *code, + pcre_extra *extra, const unsigned char *tables); +
+
+int pcre16_pattern_to_host_byte_order(pcre16 *code, + pcre16_extra *extra, const unsigned char *tables); +
+
+int pcre32_pattern_to_host_byte_order(pcre32 *code, + pcre32_extra *extra, const unsigned char *tables); +

+
+DESCRIPTION +
+

+This function ensures that the bytes in 2-byte and 4-byte values in a compiled +pattern are in the correct order for the current host. It is useful when a +pattern that has been compiled on one host is transferred to another that might +have different endianness. The arguments are: +

+  code         A compiled regular expression
+  extra        Points to an associated pcre[16|32]_extra structure,
+                 or is NULL
+  tables       Pointer to character tables, or NULL to
+                 set the built-in default
+
+The result is 0 for success, a negative PCRE_ERROR_xxx value otherwise. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_refcount.html b/doc/html/pcre_refcount.html new file mode 100644 index 0000000..bfb92e6 --- /dev/null +++ b/doc/html/pcre_refcount.html @@ -0,0 +1,51 @@ + + +pcre_refcount specification + + +

pcre_refcount man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre_refcount(pcre *code, int adjust); +

+

+int pcre16_refcount(pcre16 *code, int adjust); +

+

+int pcre32_refcount(pcre32 *code, int adjust); +

+
+DESCRIPTION +
+

+This function is used to maintain a reference count inside a data block that +contains a compiled pattern. Its arguments are: +

+  code                      Compiled regular expression
+  adjust                    Adjustment to reference value
+
+The yield of the function is the adjusted reference value, which is constrained +to lie between 0 and 65535. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_study.html b/doc/html/pcre_study.html new file mode 100644 index 0000000..af82f11 --- /dev/null +++ b/doc/html/pcre_study.html @@ -0,0 +1,68 @@ + + +pcre_study specification + + +

pcre_study man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+pcre_extra *pcre_study(const pcre *code, int options, + const char **errptr); +
+
+pcre16_extra *pcre16_study(const pcre16 *code, int options, + const char **errptr); +
+
+pcre32_extra *pcre32_study(const pcre32 *code, int options, + const char **errptr); +

+
+DESCRIPTION +
+

+This function studies a compiled pattern, to see if additional information can +be extracted that might speed up matching. Its arguments are: +

+  code       A compiled regular expression
+  options    Options for pcre[16|32]_study()
+  errptr     Where to put an error message
+
+If the function succeeds, it returns a value that can be passed to +pcre[16|32]_exec() or pcre[16|32]_dfa_exec() via their extra +arguments. +

+

+If the function returns NULL, either it could not find any additional +information, or there was an error. You can tell the difference by looking at +the error value. It is NULL in first case. +

+

+The only option is PCRE_STUDY_JIT_COMPILE. It requests just-in-time compilation +if possible. If PCRE has been compiled without JIT support, this option is +ignored. See the +pcrejit +page for further details. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_utf16_to_host_byte_order.html b/doc/html/pcre_utf16_to_host_byte_order.html new file mode 100644 index 0000000..18e7788 --- /dev/null +++ b/doc/html/pcre_utf16_to_host_byte_order.html @@ -0,0 +1,57 @@ + + +pcre_utf16_to_host_byte_order specification + + +

pcre_utf16_to_host_byte_order man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output, + PCRE_SPTR16 input, int length, int *host_byte_order, + int keep_boms); +

+
+DESCRIPTION +
+

+This function, which exists only in the 16-bit library, converts a UTF-16 +string to the correct order for the current host, taking account of any byte +order marks (BOMs) within the string. Its arguments are: +

+  output           pointer to output buffer, may be the same as input
+  input            pointer to input buffer
+  length           number of 16-bit units in the input, or negative for
+                     a zero-terminated string
+  host_byte_order  a NULL value or a non-zero value pointed to means
+                     start in host byte order
+  keep_boms        if non-zero, BOMs are copied to the output string
+
+The result of the function is the number of 16-bit units placed into the output +buffer, including the zero terminator if the string was zero-terminated. +

+

+If host_byte_order is not NULL, it is set to indicate the byte order that +is current at the end of the string. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_utf32_to_host_byte_order.html b/doc/html/pcre_utf32_to_host_byte_order.html new file mode 100644 index 0000000..772ae40 --- /dev/null +++ b/doc/html/pcre_utf32_to_host_byte_order.html @@ -0,0 +1,57 @@ + + +pcre_utf32_to_host_byte_order specification + + +

pcre_utf32_to_host_byte_order man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output, + PCRE_SPTR32 input, int length, int *host_byte_order, + int keep_boms); +

+
+DESCRIPTION +
+

+This function, which exists only in the 32-bit library, converts a UTF-32 +string to the correct order for the current host, taking account of any byte +order marks (BOMs) within the string. Its arguments are: +

+  output           pointer to output buffer, may be the same as input
+  input            pointer to input buffer
+  length           number of 32-bit units in the input, or negative for
+                     a zero-terminated string
+  host_byte_order  a NULL value or a non-zero value pointed to means
+                     start in host byte order
+  keep_boms        if non-zero, BOMs are copied to the output string
+
+The result of the function is the number of 32-bit units placed into the output +buffer, including the zero terminator if the string was zero-terminated. +

+

+If host_byte_order is not NULL, it is set to indicate the byte order that +is current at the end of the string. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcre_version.html b/doc/html/pcre_version.html new file mode 100644 index 0000000..d33e718 --- /dev/null +++ b/doc/html/pcre_version.html @@ -0,0 +1,46 @@ + + +pcre_version specification + + +

pcre_version man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+SYNOPSIS +
+

+#include <pcre.h> +

+

+const char *pcre_version(void); +

+

+const char *pcre16_version(void); +

+

+const char *pcre32_version(void); +

+
+DESCRIPTION +
+

+This function (even in the 16-bit and 32-bit libraries) returns a +zero-terminated, 8-bit character string that gives the version number of the +PCRE library and the date of its release. +

+

+There is a complete description of the PCRE native API in the +pcreapi +page and a description of the POSIX API in the +pcreposix +page. +

+Return to the PCRE index page. +

diff --git a/doc/html/pcreapi.html b/doc/html/pcreapi.html new file mode 100644 index 0000000..b401ecc --- /dev/null +++ b/doc/html/pcreapi.html @@ -0,0 +1,2922 @@ + + +pcreapi specification + + +

pcreapi man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+

+

+#include <pcre.h> +

+
PCRE NATIVE API BASIC FUNCTIONS
+

+pcre *pcre_compile(const char *pattern, int options, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre *pcre_compile2(const char *pattern, int options, + int *errorcodeptr, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre_extra *pcre_study(const pcre *code, int options, + const char **errptr); +
+
+void pcre_free_study(pcre_extra *extra); +
+
+int pcre_exec(const pcre *code, const pcre_extra *extra, + const char *subject, int length, int startoffset, + int options, int *ovector, int ovecsize); +
+
+int pcre_dfa_exec(const pcre *code, const pcre_extra *extra, + const char *subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + int *workspace, int wscount); +

+
PCRE NATIVE API STRING EXTRACTION FUNCTIONS
+

+int pcre_copy_named_substring(const pcre *code, + const char *subject, int *ovector, + int stringcount, const char *stringname, + char *buffer, int buffersize); +
+
+int pcre_copy_substring(const char *subject, int *ovector, + int stringcount, int stringnumber, char *buffer, + int buffersize); +
+
+int pcre_get_named_substring(const pcre *code, + const char *subject, int *ovector, + int stringcount, const char *stringname, + const char **stringptr); +
+
+int pcre_get_stringnumber(const pcre *code, + const char *name); +
+
+int pcre_get_stringtable_entries(const pcre *code, + const char *name, char **first, char **last); +
+
+int pcre_get_substring(const char *subject, int *ovector, + int stringcount, int stringnumber, + const char **stringptr); +
+
+int pcre_get_substring_list(const char *subject, + int *ovector, int stringcount, const char ***listptr); +
+
+void pcre_free_substring(const char *stringptr); +
+
+void pcre_free_substring_list(const char **stringptr); +

+
PCRE NATIVE API AUXILIARY FUNCTIONS
+

+int pcre_jit_exec(const pcre *code, const pcre_extra *extra, + const char *subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + pcre_jit_stack *jstack); +
+
+pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize); +
+
+void pcre_jit_stack_free(pcre_jit_stack *stack); +
+
+void pcre_assign_jit_stack(pcre_extra *extra, + pcre_jit_callback callback, void *data); +
+
+const unsigned char *pcre_maketables(void); +
+
+int pcre_fullinfo(const pcre *code, const pcre_extra *extra, + int what, void *where); +
+
+int pcre_refcount(pcre *code, int adjust); +
+
+int pcre_config(int what, void *where); +
+
+const char *pcre_version(void); +
+
+int pcre_pattern_to_host_byte_order(pcre *code, + pcre_extra *extra, const unsigned char *tables); +

+
PCRE NATIVE API INDIRECTED FUNCTIONS
+

+void *(*pcre_malloc)(size_t); +
+
+void (*pcre_free)(void *); +
+
+void *(*pcre_stack_malloc)(size_t); +
+
+void (*pcre_stack_free)(void *); +
+
+int (*pcre_callout)(pcre_callout_block *); +
+
+int (*pcre_stack_guard)(void); +

+
PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES
+

+As well as support for 8-bit character strings, PCRE also supports 16-bit +strings (from release 8.30) and 32-bit strings (from release 8.32), by means of +two additional libraries. They can be built as well as, or instead of, the +8-bit library. To avoid too much complication, this document describes the +8-bit versions of the functions, with only occasional references to the 16-bit +and 32-bit libraries. +

+

+The 16-bit and 32-bit functions operate in the same way as their 8-bit +counterparts; they just use different data types for their arguments and +results, and their names start with pcre16_ or pcre32_ instead of +pcre_. For every option that has UTF8 in its name (for example, +PCRE_UTF8), there are corresponding 16-bit and 32-bit names with UTF8 replaced +by UTF16 or UTF32, respectively. This facility is in fact just cosmetic; the +16-bit and 32-bit option names define the same bit values. +

+

+References to bytes and UTF-8 in this document should be read as references to +16-bit data units and UTF-16 when using the 16-bit library, or 32-bit data +units and UTF-32 when using the 32-bit library, unless specified otherwise. +More details of the specific differences for the 16-bit and 32-bit libraries +are given in the +pcre16 +and +pcre32 +pages. +

+
PCRE API OVERVIEW
+

+PCRE has its own native API, which is described in this document. There are +also some wrapper functions (for the 8-bit library only) that correspond to the +POSIX regular expression API, but they do not give access to all the +functionality. They are described in the +pcreposix +documentation. Both of these APIs define a set of C function calls. A C++ +wrapper (again for the 8-bit library only) is also distributed with PCRE. It is +documented in the +pcrecpp +page. +

+

+The native API C function prototypes are defined in the header file +pcre.h, and on Unix-like systems the (8-bit) library itself is called +libpcre. It can normally be accessed by adding -lpcre to the +command for linking an application that uses PCRE. The header file defines the +macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release numbers +for the library. Applications can use these to include support for different +releases of PCRE. +

+

+In a Windows environment, if you want to statically link an application program +against a non-dll pcre.a file, you must define PCRE_STATIC before +including pcre.h or pcrecpp.h, because otherwise the +pcre_malloc() and pcre_free() exported functions will be declared +__declspec(dllimport), with unwanted results. +

+

+The functions pcre_compile(), pcre_compile2(), pcre_study(), +and pcre_exec() are used for compiling and matching regular expressions +in a Perl-compatible manner. A sample program that demonstrates the simplest +way of using them is provided in the file called pcredemo.c in the PCRE +source distribution. A listing of this program is given in the +pcredemo +documentation, and the +pcresample +documentation describes how to compile and run it. +

+

+Just-in-time compiler support is an optional feature of PCRE that can be built +in appropriate hardware environments. It greatly speeds up the matching +performance of many patterns. Simple programs can easily request that it be +used if available, by setting an option that is ignored when it is not +relevant. More complicated programs might need to make use of the functions +pcre_jit_stack_alloc(), pcre_jit_stack_free(), and +pcre_assign_jit_stack() in order to control the JIT code's memory usage. +

+

+From release 8.32 there is also a direct interface for JIT execution, which +gives improved performance. The JIT-specific functions are discussed in the +pcrejit +documentation. +

+

+A second matching function, pcre_dfa_exec(), which is not +Perl-compatible, is also provided. This uses a different algorithm for the +matching. The alternative algorithm finds all possible matches (at a given +point in the subject), and scans the subject just once (unless there are +lookbehind assertions). However, this algorithm does not return captured +substrings. A description of the two matching algorithms and their advantages +and disadvantages is given in the +pcrematching +documentation. +

+

+In addition to the main compiling and matching functions, there are convenience +functions for extracting captured substrings from a subject string that is +matched by pcre_exec(). They are: +

+  pcre_copy_substring()
+  pcre_copy_named_substring()
+  pcre_get_substring()
+  pcre_get_named_substring()
+  pcre_get_substring_list()
+  pcre_get_stringnumber()
+  pcre_get_stringtable_entries()
+
+pcre_free_substring() and pcre_free_substring_list() are also +provided, to free the memory used for extracted strings. +

+

+The function pcre_maketables() is used to build a set of character tables +in the current locale for passing to pcre_compile(), pcre_exec(), +or pcre_dfa_exec(). This is an optional facility that is provided for +specialist use. Most commonly, no special tables are passed, in which case +internal tables that are generated when PCRE is built are used. +

+

+The function pcre_fullinfo() is used to find out information about a +compiled pattern. The function pcre_version() returns a pointer to a +string containing the version of PCRE and its date of release. +

+

+The function pcre_refcount() maintains a reference count in a data block +containing a compiled pattern. This is provided for the benefit of +object-oriented applications. +

+

+The global variables pcre_malloc and pcre_free initially contain +the entry points of the standard malloc() and free() functions, +respectively. PCRE calls the memory management functions via these variables, +so a calling program can replace them if it wishes to intercept the calls. This +should be done before calling any PCRE functions. +

+

+The global variables pcre_stack_malloc and pcre_stack_free are also +indirections to memory management functions. These special functions are used +only when PCRE is compiled to use the heap for remembering data, instead of +recursive function calls, when running the pcre_exec() function. See the +pcrebuild +documentation for details of how to do this. It is a non-standard way of +building PCRE, for use in environments that have limited stacks. Because of the +greater use of memory management, it runs more slowly. Separate functions are +provided so that special-purpose external code can be used for this case. When +used, these functions are always called in a stack-like manner (last obtained, +first freed), and always for memory blocks of the same size. There is a +discussion about PCRE's stack usage in the +pcrestack +documentation. +

+

+The global variable pcre_callout initially contains NULL. It can be set +by the caller to a "callout" function, which PCRE will then call at specified +points during a matching operation. Details are given in the +pcrecallout +documentation. +

+

+The global variable pcre_stack_guard initially contains NULL. It can be +set by the caller to a function that is called by PCRE whenever it starts +to compile a parenthesized part of a pattern. When parentheses are nested, PCRE +uses recursive function calls, which use up the system stack. This function is +provided so that applications with restricted stacks can force a compilation +error if the stack runs out. The function should return zero if all is well, or +non-zero to force an error. +

+
NEWLINES
+

+PCRE supports five different conventions for indicating line breaks in +strings: a single CR (carriage return) character, a single LF (linefeed) +character, the two-character sequence CRLF, any of the three preceding, or any +Unicode newline sequence. The Unicode newline sequences are the three just +mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed, +U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS +(paragraph separator, U+2029). +

+

+Each of the first three conventions is used by at least one operating system as +its standard newline sequence. When PCRE is built, a default can be specified. +The default default is LF, which is the Unix standard. When PCRE is run, the +default can be overridden, either when a pattern is compiled, or when it is +matched. +

+

+At compile time, the newline convention can be specified by the options +argument of pcre_compile(), or it can be specified by special text at the +start of the pattern itself; this overrides any other settings. See the +pcrepattern +page for details of the special character sequences. +

+

+In the PCRE documentation the word "newline" is used to mean "the character or +pair of characters that indicate a line break". The choice of newline +convention affects the handling of the dot, circumflex, and dollar +metacharacters, the handling of #-comments in /x mode, and, when CRLF is a +recognized line ending sequence, the match position advancement for a +non-anchored pattern. There is more detail about this in the +section on pcre_exec() options +below. +

+

+The choice of newline convention does not affect the interpretation of +the \n or \r escape sequences, nor does it affect what \R matches, which is +controlled in a similar way, but by separate options. +

+
MULTITHREADING
+

+The PCRE functions can be used in multi-threading applications, with the +proviso that the memory management functions pointed to by pcre_malloc, +pcre_free, pcre_stack_malloc, and pcre_stack_free, and the +callout and stack-checking functions pointed to by pcre_callout and +pcre_stack_guard, are shared by all threads. +

+

+The compiled form of a regular expression is not altered during matching, so +the same compiled pattern can safely be used by several threads at once. +

+

+If the just-in-time optimization feature is being used, it needs separate +memory stack areas for each thread. See the +pcrejit +documentation for more details. +

+
SAVING PRECOMPILED PATTERNS FOR LATER USE
+

+The compiled form of a regular expression can be saved and re-used at a later +time, possibly by a different program, and even on a host other than the one on +which it was compiled. Details are given in the +pcreprecompile +documentation, which includes a description of the +pcre_pattern_to_host_byte_order() function. However, compiling a regular +expression with one version of PCRE for use with a different version is not +guaranteed to work and may cause crashes. +

+
CHECKING BUILD-TIME OPTIONS
+

+int pcre_config(int what, void *where); +

+

+The function pcre_config() makes it possible for a PCRE client to +discover which optional features have been compiled into the PCRE library. The +pcrebuild +documentation has more details about these optional features. +

+

+The first argument for pcre_config() is an integer, specifying which +information is required; the second argument is a pointer to a variable into +which the information is placed. The returned value is zero on success, or the +negative error code PCRE_ERROR_BADOPTION if the value in the first argument is +not recognized. The following information is available: +

+  PCRE_CONFIG_UTF8
+
+The output is an integer that is set to one if UTF-8 support is available; +otherwise it is set to zero. This value should normally be given to the 8-bit +version of this function, pcre_config(). If it is given to the 16-bit +or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION. +
+  PCRE_CONFIG_UTF16
+
+The output is an integer that is set to one if UTF-16 support is available; +otherwise it is set to zero. This value should normally be given to the 16-bit +version of this function, pcre16_config(). If it is given to the 8-bit +or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION. +
+  PCRE_CONFIG_UTF32
+
+The output is an integer that is set to one if UTF-32 support is available; +otherwise it is set to zero. This value should normally be given to the 32-bit +version of this function, pcre32_config(). If it is given to the 8-bit +or 16-bit version of this function, the result is PCRE_ERROR_BADOPTION. +
+  PCRE_CONFIG_UNICODE_PROPERTIES
+
+The output is an integer that is set to one if support for Unicode character +properties is available; otherwise it is set to zero. +
+  PCRE_CONFIG_JIT
+
+The output is an integer that is set to one if support for just-in-time +compiling is available; otherwise it is set to zero. +
+  PCRE_CONFIG_JITTARGET
+
+The output is a pointer to a zero-terminated "const char *" string. If JIT +support is available, the string contains the name of the architecture for +which the JIT compiler is configured, for example "x86 32bit (little endian + +unaligned)". If JIT support is not available, the result is NULL. +
+  PCRE_CONFIG_NEWLINE
+
+The output is an integer whose value specifies the default character sequence +that is recognized as meaning "newline". The values that are supported in +ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for +ANYCRLF, and -1 for ANY. In EBCDIC environments, CR, ANYCRLF, and ANY yield the +same values. However, the value for LF is normally 21, though some EBCDIC +environments use 37. The corresponding values for CRLF are 3349 and 3365. The +default should normally correspond to the standard sequence for your operating +system. +
+  PCRE_CONFIG_BSR
+
+The output is an integer whose value indicates what character sequences the \R +escape sequence matches by default. A value of 0 means that \R matches any +Unicode line ending sequence; a value of 1 means that \R matches only CR, LF, +or CRLF. The default can be overridden when a pattern is compiled or matched. +
+  PCRE_CONFIG_LINK_SIZE
+
+The output is an integer that contains the number of bytes used for internal +linkage in compiled regular expressions. For the 8-bit library, the value can +be 2, 3, or 4. For the 16-bit library, the value is either 2 or 4 and is still +a number of bytes. For the 32-bit library, the value is either 2 or 4 and is +still a number of bytes. The default value of 2 is sufficient for all but the +most massive patterns, since it allows the compiled pattern to be up to 64K in +size. Larger values allow larger regular expressions to be compiled, at the +expense of slower matching. +
+  PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
+
+The output is an integer that contains the threshold above which the POSIX +interface uses malloc() for output vectors. Further details are given in +the +pcreposix +documentation. +
+  PCRE_CONFIG_PARENS_LIMIT
+
+The output is a long integer that gives the maximum depth of nesting of +parentheses (of any kind) in a pattern. This limit is imposed to cap the amount +of system stack used when a pattern is compiled. It is specified when PCRE is +built; the default is 250. This limit does not take into account the stack that +may already be used by the calling application. For finer control over +compilation stack usage, you can set a pointer to an external checking function +in pcre_stack_guard. +
+  PCRE_CONFIG_MATCH_LIMIT
+
+The output is a long integer that gives the default limit for the number of +internal matching function calls in a pcre_exec() execution. Further +details are given with pcre_exec() below. +
+  PCRE_CONFIG_MATCH_LIMIT_RECURSION
+
+The output is a long integer that gives the default limit for the depth of +recursion when calling the internal matching function in a pcre_exec() +execution. Further details are given with pcre_exec() below. +
+  PCRE_CONFIG_STACKRECURSE
+
+The output is an integer that is set to one if internal recursion when running +pcre_exec() is implemented by recursive function calls that use the stack +to remember their state. This is the usual way that PCRE is compiled. The +output is zero if PCRE was compiled to use blocks of data on the heap instead +of recursive function calls. In this case, pcre_stack_malloc and +pcre_stack_free are called to manage memory blocks on the heap, thus +avoiding the use of the stack. +

+
COMPILING A PATTERN
+

+pcre *pcre_compile(const char *pattern, int options, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +
+
+pcre *pcre_compile2(const char *pattern, int options, + int *errorcodeptr, + const char **errptr, int *erroffset, + const unsigned char *tableptr); +

+

+Either of the functions pcre_compile() or pcre_compile2() can be +called to compile a pattern into an internal form. The only difference between +the two interfaces is that pcre_compile2() has an additional argument, +errorcodeptr, via which a numerical error code can be returned. To avoid +too much repetition, we refer just to pcre_compile() below, but the +information applies equally to pcre_compile2(). +

+

+The pattern is a C string terminated by a binary zero, and is passed in the +pattern argument. A pointer to a single block of memory that is obtained +via pcre_malloc is returned. This contains the compiled code and related +data. The pcre type is defined for the returned block; this is a typedef +for a structure whose contents are not externally defined. It is up to the +caller to free the memory (via pcre_free) when it is no longer required. +

+

+Although the compiled code of a PCRE regex is relocatable, that is, it does not +depend on memory location, the complete pcre data block is not +fully relocatable, because it may contain a copy of the tableptr +argument, which is an address (see below). +

+

+The options argument contains various bit settings that affect the +compilation. It should be zero if no options are required. The available +options are described below. Some of them (in particular, those that are +compatible with Perl, but some others as well) can also be set and unset from +within the pattern (see the detailed description in the +pcrepattern +documentation). For those options that can be different in different parts of +the pattern, the contents of the options argument specifies their +settings at the start of compilation and execution. The PCRE_ANCHORED, +PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK, and +PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at +compile time. +

+

+If errptr is NULL, pcre_compile() returns NULL immediately. +Otherwise, if compilation of a pattern fails, pcre_compile() returns +NULL, and sets the variable pointed to by errptr to point to a textual +error message. This is a static string that is part of the library. You must +not try to free it. Normally, the offset from the start of the pattern to the +data unit that was being processed when the error was discovered is placed in +the variable pointed to by erroffset, which must not be NULL (if it is, +an immediate error is given). However, for an invalid UTF-8 or UTF-16 string, +the offset is that of the first data unit of the failing character. +

+

+Some errors are not detected until the whole pattern has been scanned; in these +cases, the offset passed back is the length of the pattern. Note that the +offset is in data units, not characters, even in a UTF mode. It may sometimes +point into the middle of a UTF-8 or UTF-16 character. +

+

+If pcre_compile2() is used instead of pcre_compile(), and the +errorcodeptr argument is not NULL, a non-zero error code number is +returned via this argument in the event of an error. This is in addition to the +textual error message. Error codes and messages are listed below. +

+

+If the final argument, tableptr, is NULL, PCRE uses a default set of +character tables that are built when PCRE is compiled, using the default C +locale. Otherwise, tableptr must be an address that is the result of a +call to pcre_maketables(). This value is stored with the compiled +pattern, and used again by pcre_exec() and pcre_dfa_exec() when the +pattern is matched. For more discussion, see the section on locale support +below. +

+

+This code fragment shows a typical straightforward call to pcre_compile(): +

+  pcre *re;
+  const char *error;
+  int erroffset;
+  re = pcre_compile(
+    "^A.*Z",          /* the pattern */
+    0,                /* default options */
+    &error,           /* for error message */
+    &erroffset,       /* for error offset */
+    NULL);            /* use default character tables */
+
+The following names for option bits are defined in the pcre.h header +file: +
+  PCRE_ANCHORED
+
+If this bit is set, the pattern is forced to be "anchored", that is, it is +constrained to match only at the first matching point in the string that is +being searched (the "subject string"). This effect can also be achieved by +appropriate constructs in the pattern itself, which is the only way to do it in +Perl. +
+  PCRE_AUTO_CALLOUT
+
+If this bit is set, pcre_compile() automatically inserts callout items, +all with number 255, before each pattern item. For discussion of the callout +facility, see the +pcrecallout +documentation. +
+  PCRE_BSR_ANYCRLF
+  PCRE_BSR_UNICODE
+
+These options (which are mutually exclusive) control what the \R escape +sequence matches. The choice is either to match only CR, LF, or CRLF, or to +match any Unicode newline sequence. The default is specified when PCRE is +built. It can be overridden from within the pattern, or by setting an option +when a compiled pattern is matched. +
+  PCRE_CASELESS
+
+If this bit is set, letters in the pattern match both upper and lower case +letters. It is equivalent to Perl's /i option, and it can be changed within a +pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the +concept of case for characters whose values are less than 128, so caseless +matching is always possible. For characters with higher values, the concept of +case is supported if PCRE is compiled with Unicode property support, but not +otherwise. If you want to use caseless matching for characters 128 and above, +you must ensure that PCRE is compiled with Unicode property support as well as +with UTF-8 support. +
+  PCRE_DOLLAR_ENDONLY
+
+If this bit is set, a dollar metacharacter in the pattern matches only at the +end of the subject string. Without this option, a dollar also matches +immediately before a newline at the end of the string (but not before any other +newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set. +There is no equivalent to this option in Perl, and no way to set it within a +pattern. +
+  PCRE_DOTALL
+
+If this bit is set, a dot metacharacter in the pattern matches a character of +any value, including one that indicates a newline. However, it only ever +matches one character, even if newlines are coded as CRLF. Without this option, +a dot does not match when the current position is at a newline. This option is +equivalent to Perl's /s option, and it can be changed within a pattern by a +(?s) option setting. A negative class such as [^a] always matches newline +characters, independent of the setting of this option. +
+  PCRE_DUPNAMES
+
+If this bit is set, names used to identify capturing subpatterns need not be +unique. This can be helpful for certain types of pattern when it is known that +only one instance of the named subpattern can ever be matched. There are more +details of named subpatterns below; see also the +pcrepattern +documentation. +
+  PCRE_EXTENDED
+
+If this bit is set, most white space characters in the pattern are totally +ignored except when escaped or inside a character class. However, white space +is not allowed within sequences such as (?> that introduce various +parenthesized subpatterns, nor within a numerical quantifier such as {1,3}. +However, ignorable white space is permitted between an item and a following +quantifier and between a quantifier and a following + that indicates +possessiveness. +

+

+White space did not used to include the VT character (code 11), because Perl +did not treat this character as white space. However, Perl changed at release +5.18, so PCRE followed at release 8.34, and VT is now treated as white space. +

+

+PCRE_EXTENDED also causes characters between an unescaped # outside a character +class and the next newline, inclusive, to be ignored. PCRE_EXTENDED is +equivalent to Perl's /x option, and it can be changed within a pattern by a +(?x) option setting. +

+

+Which characters are interpreted as newlines is controlled by the options +passed to pcre_compile() or by a special sequence at the start of the +pattern, as described in the section entitled +"Newline conventions" +in the pcrepattern documentation. Note that the end of this type of +comment is a literal newline sequence in the pattern; escape sequences that +happen to represent a newline do not count. +

+

+This option makes it possible to include comments inside complicated patterns. +Note, however, that this applies only to data characters. White space characters +may never appear within special character sequences in a pattern, for example +within the sequence (?( that introduces a conditional subpattern. +

+  PCRE_EXTRA
+
+This option was invented in order to turn on additional functionality of PCRE +that is incompatible with Perl, but it is currently of very little use. When +set, any backslash in a pattern that is followed by a letter that has no +special meaning causes an error, thus reserving these combinations for future +expansion. By default, as in Perl, a backslash followed by a letter with no +special meaning is treated as a literal. (Perl can, however, be persuaded to +give an error for this, by running it with the -w option.) There are at present +no other features controlled by this option. It can also be set by a (?X) +option setting within a pattern. +
+  PCRE_FIRSTLINE
+
+If this option is set, an unanchored pattern is required to match before or at +the first newline in the subject string, though the matched text may continue +over the newline. +
+  PCRE_JAVASCRIPT_COMPAT
+
+If this option is set, PCRE's behaviour is changed in some ways so that it is +compatible with JavaScript rather than Perl. The changes are as follows: +

+

+(1) A lone closing square bracket in a pattern causes a compile-time error, +because this is illegal in JavaScript (by default it is treated as a data +character). Thus, the pattern AB]CD becomes illegal when this option is set. +

+

+(2) At run time, a back reference to an unset subpattern group matches an empty +string (by default this causes the current matching alternative to fail). A +pattern such as (\1)(a) succeeds when this option is set (assuming it can find +an "a" in the subject), whereas it fails by default, for Perl compatibility. +

+

+(3) \U matches an upper case "U" character; by default \U causes a compile +time error (Perl uses \U to upper case subsequent characters). +

+

+(4) \u matches a lower case "u" character unless it is followed by four +hexadecimal digits, in which case the hexadecimal number defines the code point +to match. By default, \u causes a compile time error (Perl uses it to upper +case the following character). +

+

+(5) \x matches a lower case "x" character unless it is followed by two +hexadecimal digits, in which case the hexadecimal number defines the code point +to match. By default, as in Perl, a hexadecimal number is always expected after +\x, but it may have zero, one, or two digits (so, for example, \xz matches a +binary zero character followed by z). +

+  PCRE_MULTILINE
+
+By default, for the purposes of matching "start of line" and "end of line", +PCRE treats the subject string as consisting of a single line of characters, +even if it actually contains newlines. The "start of line" metacharacter (^) +matches only at the start of the string, and the "end of line" metacharacter +($) matches only at the end of the string, or before a terminating newline +(except when PCRE_DOLLAR_ENDONLY is set). Note, however, that unless +PCRE_DOTALL is set, the "any character" metacharacter (.) does not match at a +newline. This behaviour (for ^, $, and dot) is the same as Perl. +

+

+When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs +match immediately following or immediately before internal newlines in the +subject string, respectively, as well as at the very start and end. This is +equivalent to Perl's /m option, and it can be changed within a pattern by a +(?m) option setting. If there are no newlines in a subject string, or no +occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect. +

+  PCRE_NEVER_UTF
+
+This option locks out interpretation of the pattern as UTF-8 (or UTF-16 or +UTF-32 in the 16-bit and 32-bit libraries). In particular, it prevents the +creator of the pattern from switching to UTF interpretation by starting the +pattern with (*UTF). This may be useful in applications that process patterns +from external sources. The combination of PCRE_UTF8 and PCRE_NEVER_UTF also +causes an error. +
+  PCRE_NEWLINE_CR
+  PCRE_NEWLINE_LF
+  PCRE_NEWLINE_CRLF
+  PCRE_NEWLINE_ANYCRLF
+  PCRE_NEWLINE_ANY
+
+These options override the default newline definition that was chosen when PCRE +was built. Setting the first or the second specifies that a newline is +indicated by a single character (CR or LF, respectively). Setting +PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character +CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three +preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies +that any Unicode newline sequence should be recognized. +

+

+In an ASCII/Unicode environment, the Unicode newline sequences are the three +just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form +feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS +(paragraph separator, U+2029). For the 8-bit library, the last two are +recognized only in UTF-8 mode. +

+

+When PCRE is compiled to run in an EBCDIC (mainframe) environment, the code for +CR is 0x0d, the same as ASCII. However, the character code for LF is normally +0x15, though in some EBCDIC environments 0x25 is used. Whichever of these is +not LF is made to correspond to Unicode's NEL character. EBCDIC codes are all +less than 256. For more details, see the +pcrebuild +documentation. +

+

+The newline setting in the options word uses three bits that are treated +as a number, giving eight possibilities. Currently only six are used (default +plus the five values above). This means that if you set more than one newline +option, the combination may or may not be sensible. For example, +PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but +other combinations may yield unused numbers and cause an error. +

+

+The only time that a line break in a pattern is specially recognized when +compiling is when PCRE_EXTENDED is set. CR and LF are white space characters, +and so are ignored in this mode. Also, an unescaped # outside a character class +indicates a comment that lasts until after the next line break sequence. In +other circumstances, line break sequences in patterns are treated as literal +data. +

+

+The newline option that is set at compile time becomes the default that is used +for pcre_exec() and pcre_dfa_exec(), but it can be overridden. +

+  PCRE_NO_AUTO_CAPTURE
+
+If this option is set, it disables the use of numbered capturing parentheses in +the pattern. Any opening parenthesis that is not followed by ? behaves as if it +were followed by ?: but named parentheses can still be used for capturing (and +they acquire numbers in the usual way). There is no equivalent of this option +in Perl. +
+  PCRE_NO_AUTO_POSSESS
+
+If this option is set, it disables "auto-possessification". This is an +optimization that, for example, turns a+b into a++b in order to avoid +backtracks into a+ that can never be successful. However, if callouts are in +use, auto-possessification means that some of them are never taken. You can set +this option if you want the matching functions to do a full unoptimized search +and run all the callouts, but it is mainly provided for testing purposes. +
+  PCRE_NO_START_OPTIMIZE
+
+This is an option that acts at matching time; that is, it is really an option +for pcre_exec() or pcre_dfa_exec(). If it is set at compile time, +it is remembered with the compiled pattern and assumed at matching time. This +is necessary if you want to use JIT execution, because the JIT compiler needs +to know whether or not this option is set. For details see the discussion of +PCRE_NO_START_OPTIMIZE +below. +
+  PCRE_UCP
+
+This option changes the way PCRE processes \B, \b, \D, \d, \S, \s, \W, +\w, and some of the POSIX character classes. By default, only ASCII characters +are recognized, but if PCRE_UCP is set, Unicode properties are used instead to +classify characters. More details are given in the section on +generic character types +in the +pcrepattern +page. If you set PCRE_UCP, matching one of the items it affects takes much +longer. The option is available only if PCRE has been compiled with Unicode +property support. +
+  PCRE_UNGREEDY
+
+This option inverts the "greediness" of the quantifiers so that they are not +greedy by default, but become greedy if followed by "?". It is not compatible +with Perl. It can also be set by a (?U) option setting within the pattern. +
+  PCRE_UTF8
+
+This option causes PCRE to regard both the pattern and the subject as strings +of UTF-8 characters instead of single-byte strings. However, it is available +only when PCRE is built to include UTF support. If not, the use of this option +provokes an error. Details of how this option changes the behaviour of PCRE are +given in the +pcreunicode +page. +
+  PCRE_NO_UTF8_CHECK
+
+When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is +automatically checked. There is a discussion about the +validity of UTF-8 strings +in the +pcreunicode +page. If an invalid UTF-8 sequence is found, pcre_compile() returns an +error. If you already know that your pattern is valid, and you want to skip +this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK option. +When it is set, the effect of passing an invalid UTF-8 string as a pattern is +undefined. It may cause your program to crash or loop. Note that this option +can also be passed to pcre_exec() and pcre_dfa_exec(), to suppress +the validity checking of subject strings only. If the same string is being +matched many times, the option can be safely set for the second and subsequent +matchings to improve performance. +

+
COMPILATION ERROR CODES
+

+The following table lists the error codes than may be returned by +pcre_compile2(), along with the error messages that may be returned by +both compiling functions. Note that error messages are always 8-bit ASCII +strings, even in 16-bit or 32-bit mode. As PCRE has developed, some error codes +have fallen out of use. To avoid confusion, they have not been re-used. +

+   0  no error
+   1  \ at end of pattern
+   2  \c at end of pattern
+   3  unrecognized character follows \
+   4  numbers out of order in {} quantifier
+   5  number too big in {} quantifier
+   6  missing terminating ] for character class
+   7  invalid escape sequence in character class
+   8  range out of order in character class
+   9  nothing to repeat
+  10  [this code is not in use]
+  11  internal error: unexpected repeat
+  12  unrecognized character after (? or (?-
+  13  POSIX named classes are supported only within a class
+  14  missing )
+  15  reference to non-existent subpattern
+  16  erroffset passed as NULL
+  17  unknown option bit(s) set
+  18  missing ) after comment
+  19  [this code is not in use]
+  20  regular expression is too large
+  21  failed to get memory
+  22  unmatched parentheses
+  23  internal error: code overflow
+  24  unrecognized character after (?<
+  25  lookbehind assertion is not fixed length
+  26  malformed number or name after (?(
+  27  conditional group contains more than two branches
+  28  assertion expected after (?(
+  29  (?R or (?[+-]digits must be followed by )
+  30  unknown POSIX class name
+  31  POSIX collating elements are not supported
+  32  this version of PCRE is compiled without UTF support
+  33  [this code is not in use]
+  34  character value in \x{} or \o{} is too large
+  35  invalid condition (?(0)
+  36  \C not allowed in lookbehind assertion
+  37  PCRE does not support \L, \l, \N{name}, \U, or \u
+  38  number after (?C is > 255
+  39  closing ) for (?C expected
+  40  recursive call could loop indefinitely
+  41  unrecognized character after (?P
+  42  syntax error in subpattern name (missing terminator)
+  43  two named subpatterns have the same name
+  44  invalid UTF-8 string (specifically UTF-8)
+  45  support for \P, \p, and \X has not been compiled
+  46  malformed \P or \p sequence
+  47  unknown property name after \P or \p
+  48  subpattern name is too long (maximum 32 characters)
+  49  too many named subpatterns (maximum 10000)
+  50  [this code is not in use]
+  51  octal value is greater than \377 in 8-bit non-UTF-8 mode
+  52  internal error: overran compiling workspace
+  53  internal error: previously-checked referenced subpattern
+        not found
+  54  DEFINE group contains more than one branch
+  55  repeating a DEFINE group is not allowed
+  56  inconsistent NEWLINE options
+  57  \g is not followed by a braced, angle-bracketed, or quoted
+        name/number or by a plain number
+  58  a numbered reference must not be zero
+  59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
+  60  (*VERB) not recognized or malformed
+  61  number is too big
+  62  subpattern name expected
+  63  digit expected after (?+
+  64  ] is an invalid data character in JavaScript compatibility mode
+  65  different names for subpatterns of the same number are
+        not allowed
+  66  (*MARK) must have an argument
+  67  this version of PCRE is not compiled with Unicode property
+        support
+  68  \c must be followed by an ASCII character
+  69  \k is not followed by a braced, angle-bracketed, or quoted name
+  70  internal error: unknown opcode in find_fixedlength()
+  71  \N is not supported in a class
+  72  too many forward references
+  73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
+  74  invalid UTF-16 string (specifically UTF-16)
+  75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
+  76  character value in \u.... sequence is too large
+  77  invalid UTF-32 string (specifically UTF-32)
+  78  setting UTF is disabled by the application
+  79  non-hex character in \x{} (closing brace missing?)
+  80  non-octal character in \o{} (closing brace missing?)
+  81  missing opening brace after \o
+  82  parentheses are too deeply nested
+  83  invalid range in character class
+  84  group name must start with a non-digit
+  85  parentheses are too deeply nested (stack check)
+
+The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may +be used if the limits were changed when PCRE was built. +

+
STUDYING A PATTERN
+

+pcre_extra *pcre_study(const pcre *code, int options, + const char **errptr); +

+

+If a compiled pattern is going to be used several times, it is worth spending +more time analyzing it in order to speed up the time taken for matching. The +function pcre_study() takes a pointer to a compiled pattern as its first +argument. If studying the pattern produces additional information that will +help speed up matching, pcre_study() returns a pointer to a +pcre_extra block, in which the study_data field points to the +results of the study. +

+

+The returned value from pcre_study() can be passed directly to +pcre_exec() or pcre_dfa_exec(). However, a pcre_extra block +also contains other fields that can be set by the caller before the block is +passed; these are described +below +in the section on matching a pattern. +

+

+If studying the pattern does not produce any useful information, +pcre_study() returns NULL by default. In that circumstance, if the +calling program wants to pass any of the other fields to pcre_exec() or +pcre_dfa_exec(), it must set up its own pcre_extra block. However, +if pcre_study() is called with the PCRE_STUDY_EXTRA_NEEDED option, it +returns a pcre_extra block even if studying did not find any additional +information. It may still return NULL, however, if an error occurs in +pcre_study(). +

+

+The second argument of pcre_study() contains option bits. There are three +further options in addition to PCRE_STUDY_EXTRA_NEEDED: +

+  PCRE_STUDY_JIT_COMPILE
+  PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+  PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+
+If any of these are set, and the just-in-time compiler is available, the +pattern is further compiled into machine code that executes much faster than +the pcre_exec() interpretive matching function. If the just-in-time +compiler is not available, these options are ignored. All undefined bits in the +options argument must be zero. +

+

+JIT compilation is a heavyweight optimization. It can take some time for +patterns to be analyzed, and for one-off matches and simple patterns the +benefit of faster execution might be offset by a much slower study time. +Not all patterns can be optimized by the JIT compiler. For those that cannot be +handled, matching automatically falls back to the pcre_exec() +interpreter. For more details, see the +pcrejit +documentation. +

+

+The third argument for pcre_study() is a pointer for an error message. If +studying succeeds (even if no data is returned), the variable it points to is +set to NULL. Otherwise it is set to point to a textual error message. This is a +static string that is part of the library. You must not try to free it. You +should test the error pointer for NULL after calling pcre_study(), to be +sure that it has run successfully. +

+

+When you are finished with a pattern, you can free the memory used for the +study data by calling pcre_free_study(). This function was added to the +API for release 8.20. For earlier versions, the memory could be freed with +pcre_free(), just like the pattern itself. This will still work in cases +where JIT optimization is not used, but it is advisable to change to the new +function when convenient. +

+

+This is a typical way in which pcre_study() is used (except that in a +real application there should be tests for errors): +

+  int rc;
+  pcre *re;
+  pcre_extra *sd;
+  re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
+  sd = pcre_study(
+    re,             /* result of pcre_compile() */
+    0,              /* no options */
+    &error);        /* set to NULL or points to a message */
+  rc = pcre_exec(   /* see below for details of pcre_exec() options */
+    re, sd, "subject", 7, 0, 0, ovector, 30);
+  ...
+  pcre_free_study(sd);
+  pcre_free(re);
+
+Studying a pattern does two things: first, a lower bound for the length of +subject string that is needed to match the pattern is computed. This does not +mean that there are any strings of that length that match, but it does +guarantee that no shorter strings match. The value is used to avoid wasting +time by trying to match strings that are shorter than the lower bound. You can +find out the value in a calling program via the pcre_fullinfo() function. +

+

+Studying a pattern is also useful for non-anchored patterns that do not have a +single fixed starting character. A bitmap of possible starting bytes is +created. This speeds up finding a position in the subject at which to start +matching. (In 16-bit mode, the bitmap is used for 16-bit values less than 256. +In 32-bit mode, the bitmap is used for 32-bit values less than 256.) +

+

+These two optimizations apply to both pcre_exec() and +pcre_dfa_exec(), and the information is also used by the JIT compiler. +The optimizations can be disabled by setting the PCRE_NO_START_OPTIMIZE option. +You might want to do this if your pattern contains callouts or (*MARK) and you +want to make use of these facilities in cases where matching fails. +

+

+PCRE_NO_START_OPTIMIZE can be specified at either compile time or execution +time. However, if PCRE_NO_START_OPTIMIZE is passed to pcre_exec(), (that +is, after any JIT compilation has happened) JIT execution is disabled. For JIT +execution to work with PCRE_NO_START_OPTIMIZE, the option must be set at +compile time. +

+

+There is a longer discussion of PCRE_NO_START_OPTIMIZE +below. +

+
LOCALE SUPPORT
+

+PCRE handles caseless matching, and determines whether characters are letters, +digits, or whatever, by reference to a set of tables, indexed by character +code point. When running in UTF-8 mode, or in the 16- or 32-bit libraries, this +applies only to characters with code points less than 256. By default, +higher-valued code points never match escapes such as \w or \d. However, if +PCRE is built with Unicode property support, all characters can be tested with +\p and \P, or, alternatively, the PCRE_UCP option can be set when a pattern +is compiled; this causes \w and friends to use Unicode property support +instead of the built-in tables. +

+

+The use of locales with Unicode is discouraged. If you are handling characters +with code points greater than 128, you should either use Unicode support, or +use locales, but not try to mix the two. +

+

+PCRE contains an internal set of tables that are used when the final argument +of pcre_compile() is NULL. These are sufficient for many applications. +Normally, the internal tables recognize only ASCII characters. However, when +PCRE is built, it is possible to cause the internal tables to be rebuilt in the +default "C" locale of the local system, which may cause them to be different. +

+

+The internal tables can always be overridden by tables supplied by the +application that calls PCRE. These may be created in a different locale from +the default. As more and more applications change to using Unicode, the need +for this locale support is expected to die away. +

+

+External tables are built by calling the pcre_maketables() function, +which has no arguments, in the relevant locale. The result can then be passed +to pcre_compile() as often as necessary. For example, to build and use +tables that are appropriate for the French locale (where accented characters +with values greater than 128 are treated as letters), the following code could +be used: +

+  setlocale(LC_CTYPE, "fr_FR");
+  tables = pcre_maketables();
+  re = pcre_compile(..., tables);
+
+The locale name "fr_FR" is used on Linux and other Unix-like systems; if you +are using Windows, the name for the French locale is "french". +

+

+When pcre_maketables() runs, the tables are built in memory that is +obtained via pcre_malloc. It is the caller's responsibility to ensure +that the memory containing the tables remains available for as long as it is +needed. +

+

+The pointer that is passed to pcre_compile() is saved with the compiled +pattern, and the same tables are used via this pointer by pcre_study() +and also by pcre_exec() and pcre_dfa_exec(). Thus, for any single +pattern, compilation, studying and matching all happen in the same locale, but +different patterns can be processed in different locales. +

+

+It is possible to pass a table pointer or NULL (indicating the use of the +internal tables) to pcre_exec() or pcre_dfa_exec() (see the +discussion below in the section on matching a pattern). This facility is +provided for use with pre-compiled patterns that have been saved and reloaded. +Character tables are not saved with patterns, so if a non-standard table was +used at compile time, it must be provided again when the reloaded pattern is +matched. Attempting to use this facility to match a pattern in a different +locale from the one in which it was compiled is likely to lead to anomalous +(usually incorrect) results. +

+
INFORMATION ABOUT A PATTERN
+

+int pcre_fullinfo(const pcre *code, const pcre_extra *extra, + int what, void *where); +

+

+The pcre_fullinfo() function returns information about a compiled +pattern. It replaces the pcre_info() function, which was removed from the +library at version 8.30, after more than 10 years of obsolescence. +

+

+The first argument for pcre_fullinfo() is a pointer to the compiled +pattern. The second argument is the result of pcre_study(), or NULL if +the pattern was not studied. The third argument specifies which piece of +information is required, and the fourth argument is a pointer to a variable +to receive the data. The yield of the function is zero for success, or one of +the following negative numbers: +

+  PCRE_ERROR_NULL           the argument code was NULL
+                            the argument where was NULL
+  PCRE_ERROR_BADMAGIC       the "magic number" was not found
+  PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
+                            endianness
+  PCRE_ERROR_BADOPTION      the value of what was invalid
+  PCRE_ERROR_UNSET          the requested field is not set
+
+The "magic number" is placed at the start of each compiled pattern as an simple +check against passing an arbitrary memory pointer. The endianness error can +occur if a compiled pattern is saved and reloaded on a different host. Here is +a typical call of pcre_fullinfo(), to obtain the length of the compiled +pattern: +
+  int rc;
+  size_t length;
+  rc = pcre_fullinfo(
+    re,               /* result of pcre_compile() */
+    sd,               /* result of pcre_study(), or NULL */
+    PCRE_INFO_SIZE,   /* what is required */
+    &length);         /* where to put the data */
+
+The possible values for the third argument are defined in pcre.h, and are +as follows: +
+  PCRE_INFO_BACKREFMAX
+
+Return the number of the highest back reference in the pattern. The fourth +argument should point to an int variable. Zero is returned if there are +no back references. +
+  PCRE_INFO_CAPTURECOUNT
+
+Return the number of capturing subpatterns in the pattern. The fourth argument +should point to an int variable. +
+  PCRE_INFO_DEFAULT_TABLES
+
+Return a pointer to the internal default character tables within PCRE. The +fourth argument should point to an unsigned char * variable. This +information call is provided for internal use by the pcre_study() +function. External callers can cause PCRE to use its internal tables by passing +a NULL table pointer. +
+  PCRE_INFO_FIRSTBYTE (deprecated)
+
+Return information about the first data unit of any matched string, for a +non-anchored pattern. The name of this option refers to the 8-bit library, +where data units are bytes. The fourth argument should point to an int +variable. Negative values are used for special cases. However, this means that +when the 32-bit library is in non-UTF-32 mode, the full 32-bit range of +characters cannot be returned. For this reason, this value is deprecated; use +PCRE_INFO_FIRSTCHARACTERFLAGS and PCRE_INFO_FIRSTCHARACTER instead. +

+

+If there is a fixed first value, for example, the letter "c" from a pattern +such as (cat|cow|coyote), its value is returned. In the 8-bit library, the +value is always less than 256. In the 16-bit library the value can be up to +0xffff. In the 32-bit library the value can be up to 0x10ffff. +

+

+If there is no fixed first value, and if either +
+
+(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch +starts with "^", or +
+
+(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set +(if it were set, the pattern would be anchored), +
+
+-1 is returned, indicating that the pattern matches only at the start of a +subject string or after any newline within the string. Otherwise -2 is +returned. For anchored patterns, -2 is returned. +

+  PCRE_INFO_FIRSTCHARACTER
+
+Return the value of the first data unit (non-UTF character) of any matched +string in the situation where PCRE_INFO_FIRSTCHARACTERFLAGS returns 1; +otherwise return 0. The fourth argument should point to an uint_t +variable. +

+

+In the 8-bit library, the value is always less than 256. In the 16-bit library +the value can be up to 0xffff. In the 32-bit library in UTF-32 mode the value +can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32 mode. +

+  PCRE_INFO_FIRSTCHARACTERFLAGS
+
+Return information about the first data unit of any matched string, for a +non-anchored pattern. The fourth argument should point to an int +variable. +

+

+If there is a fixed first value, for example, the letter "c" from a pattern +such as (cat|cow|coyote), 1 is returned, and the character value can be +retrieved using PCRE_INFO_FIRSTCHARACTER. If there is no fixed first value, and +if either +
+
+(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch +starts with "^", or +
+
+(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set +(if it were set, the pattern would be anchored), +
+
+2 is returned, indicating that the pattern matches only at the start of a +subject string or after any newline within the string. Otherwise 0 is +returned. For anchored patterns, 0 is returned. +

+  PCRE_INFO_FIRSTTABLE
+
+If the pattern was studied, and this resulted in the construction of a 256-bit +table indicating a fixed set of values for the first data unit in any matching +string, a pointer to the table is returned. Otherwise NULL is returned. The +fourth argument should point to an unsigned char * variable. +
+  PCRE_INFO_HASCRORLF
+
+Return 1 if the pattern contains any explicit matches for CR or LF characters, +otherwise 0. The fourth argument should point to an int variable. An +explicit match is either a literal CR or LF character, or \r or \n. +
+  PCRE_INFO_JCHANGED
+
+Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise +0. The fourth argument should point to an int variable. (?J) and +(?-J) set and unset the local PCRE_DUPNAMES option, respectively. +
+  PCRE_INFO_JIT
+
+Return 1 if the pattern was studied with one of the JIT options, and +just-in-time compiling was successful. The fourth argument should point to an +int variable. A return value of 0 means that JIT support is not available +in this version of PCRE, or that the pattern was not studied with a JIT option, +or that the JIT compiler could not handle this particular pattern. See the +pcrejit +documentation for details of what can and cannot be handled. +
+  PCRE_INFO_JITSIZE
+
+If the pattern was successfully studied with a JIT option, return the size of +the JIT compiled code, otherwise return zero. The fourth argument should point +to a size_t variable. +
+  PCRE_INFO_LASTLITERAL
+
+Return the value of the rightmost literal data unit that must exist in any +matched string, other than at its start, if such a value has been recorded. The +fourth argument should point to an int variable. If there is no such +value, -1 is returned. For anchored patterns, a last literal value is recorded +only if it follows something of variable length. For example, for the pattern +/^a\d+z\d+/ the returned value is "z", but for /^a\dz\d/ the returned value +is -1. +

+

+Since for the 32-bit library using the non-UTF-32 mode, this function is unable +to return the full 32-bit range of characters, this value is deprecated; +instead the PCRE_INFO_REQUIREDCHARFLAGS and PCRE_INFO_REQUIREDCHAR values should +be used. +

+  PCRE_INFO_MATCH_EMPTY
+
+Return 1 if the pattern can match an empty string, otherwise 0. The fourth +argument should point to an int variable. +
+  PCRE_INFO_MATCHLIMIT
+
+If the pattern set a match limit by including an item of the form +(*LIMIT_MATCH=nnnn) at the start, the value is returned. The fourth argument +should point to an unsigned 32-bit integer. If no such value has been set, the +call to pcre_fullinfo() returns the error PCRE_ERROR_UNSET. +
+  PCRE_INFO_MAXLOOKBEHIND
+
+Return the number of characters (NB not data units) in the longest lookbehind +assertion in the pattern. This information is useful when doing multi-segment +matching using the partial matching facilities. Note that the simple assertions +\b and \B require a one-character lookbehind. \A also registers a +one-character lookbehind, though it does not actually inspect the previous +character. This is to ensure that at least one character from the old segment +is retained when a new segment is processed. Otherwise, if there are no +lookbehinds in the pattern, \A might match incorrectly at the start of a new +segment. +
+  PCRE_INFO_MINLENGTH
+
+If the pattern was studied and a minimum length for matching subject strings +was computed, its value is returned. Otherwise the returned value is -1. The +value is a number of characters, which in UTF mode may be different from the +number of data units. The fourth argument should point to an int +variable. A non-negative value is a lower bound to the length of any matching +string. There may not be any strings of that length that do actually match, but +every string that does match is at least that long. +
+  PCRE_INFO_NAMECOUNT
+  PCRE_INFO_NAMEENTRYSIZE
+  PCRE_INFO_NAMETABLE
+
+PCRE supports the use of named as well as numbered capturing parentheses. The +names are just an additional way of identifying the parentheses, which still +acquire numbers. Several convenience functions such as +pcre_get_named_substring() are provided for extracting captured +substrings by name. It is also possible to extract the data directly, by first +converting the name to a number in order to access the correct pointers in the +output vector (described with pcre_exec() below). To do the conversion, +you need to use the name-to-number map, which is described by these three +values. +

+

+The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives +the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each +entry; both of these return an int value. The entry size depends on the +length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first +entry of the table. This is a pointer to char in the 8-bit library, where +the first two bytes of each entry are the number of the capturing parenthesis, +most significant byte first. In the 16-bit library, the pointer points to +16-bit data units, the first of which contains the parenthesis number. In the +32-bit library, the pointer points to 32-bit data units, the first of which +contains the parenthesis number. The rest of the entry is the corresponding +name, zero terminated. +

+

+The names are in alphabetical order. If (?| is used to create multiple groups +with the same number, as described in the +section on duplicate subpattern numbers +in the +pcrepattern +page, the groups may be given the same name, but there is only one entry in the +table. Different names for groups of the same number are not permitted. +Duplicate names for subpatterns with different numbers are permitted, +but only if PCRE_DUPNAMES is set. They appear in the table in the order in +which they were found in the pattern. In the absence of (?| this is the order +of increasing number; when (?| is used this is not necessarily the case because +later subpatterns may have lower numbers. +

+

+As a simple example of the name/number table, consider the following pattern +after compilation by the 8-bit library (assume PCRE_EXTENDED is set, so white +space - including newlines - is ignored): +

+  (?<date> (?<year>(\d\d)?\d\d) - (?<month>\d\d) - (?<day>\d\d) )
+
+There are four named subpatterns, so the table has four entries, and each entry +in the table is eight bytes long. The table is as follows, with non-printing +bytes shows in hexadecimal, and undefined bytes shown as ??: +
+  00 01 d  a  t  e  00 ??
+  00 05 d  a  y  00 ?? ??
+  00 04 m  o  n  t  h  00
+  00 02 y  e  a  r  00 ??
+
+When writing code to extract data from named subpatterns using the +name-to-number map, remember that the length of the entries is likely to be +different for each compiled pattern. +
+  PCRE_INFO_OKPARTIAL
+
+Return 1 if the pattern can be used for partial matching with +pcre_exec(), otherwise 0. The fourth argument should point to an +int variable. From release 8.00, this always returns 1, because the +restrictions that previously applied to partial matching have been lifted. The +pcrepartial +documentation gives details of partial matching. +
+  PCRE_INFO_OPTIONS
+
+Return a copy of the options with which the pattern was compiled. The fourth +argument should point to an unsigned long int variable. These option bits +are those specified in the call to pcre_compile(), modified by any +top-level option settings at the start of the pattern itself. In other words, +they are the options that will be in force when matching starts. For example, +if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the +result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED. +

+

+A pattern is automatically anchored by PCRE if all of its top-level +alternatives begin with one of the following: +

+  ^     unless PCRE_MULTILINE is set
+  \A    always
+  \G    always
+  .*    if PCRE_DOTALL is set and there are no back references to the subpattern in which .* appears
+
+For such patterns, the PCRE_ANCHORED bit is set in the options returned by +pcre_fullinfo(). +
+  PCRE_INFO_RECURSIONLIMIT
+
+If the pattern set a recursion limit by including an item of the form +(*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth +argument should point to an unsigned 32-bit integer. If no such value has been +set, the call to pcre_fullinfo() returns the error PCRE_ERROR_UNSET. +
+  PCRE_INFO_SIZE
+
+Return the size of the compiled pattern in bytes (for all three libraries). The +fourth argument should point to a size_t variable. This value does not +include the size of the pcre structure that is returned by +pcre_compile(). The value that is passed as the argument to +pcre_malloc() when pcre_compile() is getting memory in which to +place the compiled data is the value returned by this option plus the size of +the pcre structure. Studying a compiled pattern, with or without JIT, +does not alter the value returned by this option. +
+  PCRE_INFO_STUDYSIZE
+
+Return the size in bytes (for all three libraries) of the data block pointed to +by the study_data field in a pcre_extra block. If pcre_extra +is NULL, or there is no study data, zero is returned. The fourth argument +should point to a size_t variable. The study_data field is set by +pcre_study() to record information that will speed up matching (see the +section entitled +"Studying a pattern" +above). The format of the study_data block is private, but its length +is made available via this option so that it can be saved and restored (see the +pcreprecompile +documentation for details). +
+  PCRE_INFO_REQUIREDCHARFLAGS
+
+Returns 1 if there is a rightmost literal data unit that must exist in any +matched string, other than at its start. The fourth argument should point to +an int variable. If there is no such value, 0 is returned. If returning +1, the character value itself can be retrieved using PCRE_INFO_REQUIREDCHAR. +

+

+For anchored patterns, a last literal value is recorded only if it follows +something of variable length. For example, for the pattern /^a\d+z\d+/ the +returned value 1 (with "z" returned from PCRE_INFO_REQUIREDCHAR), but for +/^a\dz\d/ the returned value is 0. +

+  PCRE_INFO_REQUIREDCHAR
+
+Return the value of the rightmost literal data unit that must exist in any +matched string, other than at its start, if such a value has been recorded. The +fourth argument should point to an uint32_t variable. If there is no such +value, 0 is returned. +

+
REFERENCE COUNTS
+

+int pcre_refcount(pcre *code, int adjust); +

+

+The pcre_refcount() function is used to maintain a reference count in the +data block that contains a compiled pattern. It is provided for the benefit of +applications that operate in an object-oriented manner, where different parts +of the application may be using the same compiled pattern, but you want to free +the block when they are all done. +

+

+When a pattern is compiled, the reference count field is initialized to zero. +It is changed only by calling this function, whose action is to add the +adjust value (which may be positive or negative) to it. The yield of the +function is the new value. However, the value of the count is constrained to +lie between 0 and 65535, inclusive. If the new value is outside these limits, +it is forced to the appropriate limit value. +

+

+Except when it is zero, the reference count is not correctly preserved if a +pattern is compiled on one host and then transferred to a host whose byte-order +is different. (This seems a highly unlikely scenario.) +

+
MATCHING A PATTERN: THE TRADITIONAL FUNCTION
+

+int pcre_exec(const pcre *code, const pcre_extra *extra, + const char *subject, int length, int startoffset, + int options, int *ovector, int ovecsize); +

+

+The function pcre_exec() is called to match a subject string against a +compiled pattern, which is passed in the code argument. If the +pattern was studied, the result of the study should be passed in the +extra argument. You can call pcre_exec() with the same code +and extra arguments as many times as you like, in order to match +different subject strings with the same pattern. +

+

+This function is the main matching facility of the library, and it operates in +a Perl-like manner. For specialist use there is also an alternative matching +function, which is described +below +in the section about the pcre_dfa_exec() function. +

+

+In most applications, the pattern will have been compiled (and optionally +studied) in the same process that calls pcre_exec(). However, it is +possible to save compiled patterns and study data, and then use them later +in different processes, possibly even on different hosts. For a discussion +about this, see the +pcreprecompile +documentation. +

+

+Here is an example of a simple call to pcre_exec(): +

+  int rc;
+  int ovector[30];
+  rc = pcre_exec(
+    re,             /* result of pcre_compile() */
+    NULL,           /* we didn't study the pattern */
+    "some string",  /* the subject string */
+    11,             /* the length of the subject string */
+    0,              /* start at offset 0 in the subject */
+    0,              /* default options */
+    ovector,        /* vector of integers for substring information */
+    30);            /* number of elements (NOT size in bytes) */
+
+

+
+Extra data for pcre_exec() +
+

+If the extra argument is not NULL, it must point to a pcre_extra +data block. The pcre_study() function returns such a block (when it +doesn't return NULL), but you can also create one for yourself, and pass +additional information in it. The pcre_extra block contains the following +fields (not necessarily in this order): +

+  unsigned long int flags;
+  void *study_data;
+  void *executable_jit;
+  unsigned long int match_limit;
+  unsigned long int match_limit_recursion;
+  void *callout_data;
+  const unsigned char *tables;
+  unsigned char **mark;
+
+In the 16-bit version of this structure, the mark field has type +"PCRE_UCHAR16 **". +
+
+In the 32-bit version of this structure, the mark field has type +"PCRE_UCHAR32 **". +

+

+The flags field is used to specify which of the other fields are set. The +flag bits are: +

+  PCRE_EXTRA_CALLOUT_DATA
+  PCRE_EXTRA_EXECUTABLE_JIT
+  PCRE_EXTRA_MARK
+  PCRE_EXTRA_MATCH_LIMIT
+  PCRE_EXTRA_MATCH_LIMIT_RECURSION
+  PCRE_EXTRA_STUDY_DATA
+  PCRE_EXTRA_TABLES
+
+Other flag bits should be set to zero. The study_data field and sometimes +the executable_jit field are set in the pcre_extra block that is +returned by pcre_study(), together with the appropriate flag bits. You +should not set these yourself, but you may add to the block by setting other +fields and their corresponding flag bits. +

+

+The match_limit field provides a means of preventing PCRE from using up a +vast amount of resources when running patterns that are not going to match, +but which have a very large number of possibilities in their search trees. The +classic example is a pattern that uses nested unlimited repeats. +

+

+Internally, pcre_exec() uses a function called match(), which it +calls repeatedly (sometimes recursively). The limit set by match_limit is +imposed on the number of times this function is called during a match, which +has the effect of limiting the amount of backtracking that can take place. For +patterns that are not anchored, the count restarts from zero for each position +in the subject string. +

+

+When pcre_exec() is called with a pattern that was successfully studied +with a JIT option, the way that the matching is executed is entirely different. +However, there is still the possibility of runaway matching that goes on for a +very long time, and so the match_limit value is also used in this case +(but in a different way) to limit how long the matching can continue. +

+

+The default value for the limit can be set when PCRE is built; the default +default is 10 million, which handles all but the most extreme cases. You can +override the default by suppling pcre_exec() with a pcre_extra +block in which match_limit is set, and PCRE_EXTRA_MATCH_LIMIT is set in +the flags field. If the limit is exceeded, pcre_exec() returns +PCRE_ERROR_MATCHLIMIT. +

+

+A value for the match limit may also be supplied by an item at the start of a +pattern of the form +

+  (*LIMIT_MATCH=d)
+
+where d is a decimal number. However, such a setting is ignored unless d is +less than the limit set by the caller of pcre_exec() or, if no such limit +is set, less than the default. +

+

+The match_limit_recursion field is similar to match_limit, but +instead of limiting the total number of times that match() is called, it +limits the depth of recursion. The recursion depth is a smaller number than the +total number of calls, because not all calls to match() are recursive. +This limit is of use only if it is set smaller than match_limit. +

+

+Limiting the recursion depth limits the amount of machine stack that can be +used, or, when PCRE has been compiled to use memory on the heap instead of the +stack, the amount of heap memory that can be used. This limit is not relevant, +and is ignored, when matching is done using JIT compiled code. +

+

+The default value for match_limit_recursion can be set when PCRE is +built; the default default is the same value as the default for +match_limit. You can override the default by suppling pcre_exec() +with a pcre_extra block in which match_limit_recursion is set, and +PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the flags field. If the limit +is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT. +

+

+A value for the recursion limit may also be supplied by an item at the start of +a pattern of the form +

+  (*LIMIT_RECURSION=d)
+
+where d is a decimal number. However, such a setting is ignored unless d is +less than the limit set by the caller of pcre_exec() or, if no such limit +is set, less than the default. +

+

+The callout_data field is used in conjunction with the "callout" feature, +and is described in the +pcrecallout +documentation. +

+

+The tables field is provided for use with patterns that have been +pre-compiled using custom character tables, saved to disc or elsewhere, and +then reloaded, because the tables that were used to compile a pattern are not +saved with it. See the +pcreprecompile +documentation for a discussion of saving compiled patterns for later use. If +NULL is passed using this mechanism, it forces PCRE's internal tables to be +used. +

+

+Warning: The tables that pcre_exec() uses must be the same as those +that were used when the pattern was compiled. If this is not the case, the +behaviour of pcre_exec() is undefined. Therefore, when a pattern is +compiled and matched in the same process, this field should never be set. In +this (the most common) case, the correct table pointer is automatically passed +with the compiled pattern from pcre_compile() to pcre_exec(). +

+

+If PCRE_EXTRA_MARK is set in the flags field, the mark field must +be set to point to a suitable variable. If the pattern contains any +backtracking control verbs such as (*MARK:NAME), and the execution ends up with +a name to pass back, a pointer to the name string (zero terminated) is placed +in the variable pointed to by the mark field. The names are within the +compiled pattern; if you wish to retain such a name you must copy it before +freeing the memory of a compiled pattern. If there is no name to pass back, the +variable pointed to by the mark field is set to NULL. For details of the +backtracking control verbs, see the section entitled +"Backtracking control" +in the +pcrepattern +documentation. +

+
+Option bits for pcre_exec() +
+

+The unused bits of the options argument for pcre_exec() must be +zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx, +PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, +PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and +PCRE_PARTIAL_SOFT. +

+

+If the pattern was successfully studied with one of the just-in-time (JIT) +compile options, the only supported options for JIT execution are +PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, +PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an +unsupported option is used, JIT execution is disabled and the normal +interpretive code in pcre_exec() is run. +

+  PCRE_ANCHORED
+
+The PCRE_ANCHORED option limits pcre_exec() to matching at the first +matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out +to be anchored by virtue of its contents, it cannot be made unachored at +matching time. +
+  PCRE_BSR_ANYCRLF
+  PCRE_BSR_UNICODE
+
+These options (which are mutually exclusive) control what the \R escape +sequence matches. The choice is either to match only CR, LF, or CRLF, or to +match any Unicode newline sequence. These options override the choice that was +made or defaulted when the pattern was compiled. +
+  PCRE_NEWLINE_CR
+  PCRE_NEWLINE_LF
+  PCRE_NEWLINE_CRLF
+  PCRE_NEWLINE_ANYCRLF
+  PCRE_NEWLINE_ANY
+
+These options override the newline definition that was chosen or defaulted when +the pattern was compiled. For details, see the description of +pcre_compile() above. During matching, the newline choice affects the +behaviour of the dot, circumflex, and dollar metacharacters. It may also alter +the way the match position is advanced after a match failure for an unanchored +pattern. +

+

+When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a +match attempt for an unanchored pattern fails when the current position is at a +CRLF sequence, and the pattern contains no explicit matches for CR or LF +characters, the match position is advanced by two characters instead of one, in +other words, to after the CRLF. +

+

+The above rule is a compromise that makes the most common cases work as +expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not +set), it does not match the string "\r\nA" because, after failing at the +start, it skips both the CR and the LF before retrying. However, the pattern +[\r\n]A does match that string, because it contains an explicit CR or LF +reference, and so advances only by one character after the first failure. +

+

+An explicit match for CR of LF is either a literal appearance of one of those +characters, or one of the \r or \n escape sequences. Implicit matches such as +[^X] do not count, nor does \s (which includes CR and LF in the characters +that it matches). +

+

+Notwithstanding the above, anomalous effects may still occur when CRLF is a +valid newline sequence and explicit \r or \n escapes appear in the pattern. +

+  PCRE_NOTBOL
+
+This option specifies that first character of the subject string is not the +beginning of a line, so the circumflex metacharacter should not match before +it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex +never to match. This option affects only the behaviour of the circumflex +metacharacter. It does not affect \A. +
+  PCRE_NOTEOL
+
+This option specifies that the end of the subject string is not the end of a +line, so the dollar metacharacter should not match it nor (except in multiline +mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at +compile time) causes dollar never to match. This option affects only the +behaviour of the dollar metacharacter. It does not affect \Z or \z. +
+  PCRE_NOTEMPTY
+
+An empty string is not considered to be a valid match if this option is set. If +there are alternatives in the pattern, they are tried. If all the alternatives +match the empty string, the entire match fails. For example, if the pattern +
+  a?b?
+
+is applied to a string not beginning with "a" or "b", it matches an empty +string at the start of the subject. With PCRE_NOTEMPTY set, this match is not +valid, so PCRE searches further into the string for occurrences of "a" or "b". +
+  PCRE_NOTEMPTY_ATSTART
+
+This is like PCRE_NOTEMPTY, except that an empty string match that is not at +the start of the subject is permitted. If the pattern is anchored, such a match +can occur only if the pattern contains \K. +

+

+Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it +does make a special case of a pattern match of the empty string within its +split() function, and when using the /g modifier. It is possible to +emulate Perl's behaviour after matching a null string by first trying the match +again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then +if that fails, by advancing the starting offset (see below) and trying an +ordinary match again. There is some code that demonstrates how to do this in +the +pcredemo +sample program. In the most general case, you have to check to see if the +newline convention recognizes CRLF as a newline, and if so, and the current +character is CR followed by LF, advance the starting offset by two characters +instead of one. +

+  PCRE_NO_START_OPTIMIZE
+
+There are a number of optimizations that pcre_exec() uses at the start of +a match, in order to speed up the process. For example, if it is known that an +unanchored match must start with a specific character, it searches the subject +for that character, and fails immediately if it cannot find it, without +actually running the main matching function. This means that a special item +such as (*COMMIT) at the start of a pattern is not considered until after a +suitable starting point for the match has been found. Also, when callouts or +(*MARK) items are in use, these "start-up" optimizations can cause them to be +skipped if the pattern is never actually used. The start-up optimizations are +in effect a pre-scan of the subject that takes place before the pattern is run. +

+

+The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly +causing performance to suffer, but ensuring that in cases where the result is +"no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK) +are considered at every possible starting position in the subject string. If +PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching +time. The use of PCRE_NO_START_OPTIMIZE at matching time (that is, passing it +to pcre_exec()) disables JIT execution; in this situation, matching is +always done using interpretively. +

+

+Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation. +Consider the pattern +

+  (*COMMIT)ABC
+
+When this is compiled, PCRE records the fact that a match must start with the +character "A". Suppose the subject string is "DEFABC". The start-up +optimization scans along the subject, finds "A" and runs the first match +attempt from there. The (*COMMIT) item means that the pattern must match the +current starting position, which in this case, it does. However, if the same +match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the +subject string does not happen. The first match attempt is run starting from +"D" and when this fails, (*COMMIT) prevents any further matches being tried, so +the overall result is "no match". If the pattern is studied, more start-up +optimizations may be used. For example, a minimum length for the subject may be +recorded. Consider the pattern +
+  (*MARK:A)(X|Y)
+
+The minimum length for a match is one character. If the subject is "ABC", there +will be attempts to match "ABC", "BC", "C", and then finally an empty string. +If the pattern is studied, the final attempt does not take place, because PCRE +knows that the subject is too short, and so the (*MARK) is never encountered. +In this case, studying the pattern does not affect the overall match result, +which is still "no match", but it does affect the auxiliary information that is +returned. +
+  PCRE_NO_UTF8_CHECK
+
+When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8 +string is automatically checked when pcre_exec() is subsequently called. +The entire string is checked before any other processing takes place. The value +of startoffset is also checked to ensure that it points to the start of a +UTF-8 character. There is a discussion about the +validity of UTF-8 strings +in the +pcreunicode +page. If an invalid sequence of bytes is found, pcre_exec() returns the +error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a +truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In both +cases, information about the precise nature of the error may also be returned +(see the descriptions of these errors in the section entitled \fIError return +values from\fP pcre_exec() +below). +If startoffset contains a value that does not point to the start of a +UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is +returned. +

+

+If you already know that your subject is valid, and you want to skip these +checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when +calling pcre_exec(). You might want to do this for the second and +subsequent calls to pcre_exec() if you are making repeated calls to find +all the matches in a single subject string. However, you should be sure that +the value of startoffset points to the start of a character (or the end +of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an +invalid string as a subject or an invalid value of startoffset is +undefined. Your program may crash or loop. +

+  PCRE_PARTIAL_HARD
+  PCRE_PARTIAL_SOFT
+
+These options turn on the partial matching feature. For backwards +compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match +occurs if the end of the subject string is reached successfully, but there are +not enough subject characters to complete the match. If this happens when +PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by +testing any remaining alternatives. Only if no complete match can be found is +PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words, +PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match, +but only if no complete match can be found. +

+

+If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a +partial match is found, pcre_exec() immediately returns +PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words, +when PCRE_PARTIAL_HARD is set, a partial match is considered to be more +important that an alternative complete match. +

+

+In both cases, the portion of the string that was inspected when the partial +match was found is set as the first matching string. There is a more detailed +discussion of partial and multi-segment matching, with examples, in the +pcrepartial +documentation. +

+
+The string to be matched by pcre_exec() +
+

+The subject string is passed to pcre_exec() as a pointer in +subject, a length in length, and a starting offset in +startoffset. The units for length and startoffset are bytes +for the 8-bit library, 16-bit data items for the 16-bit library, and 32-bit +data items for the 32-bit library. +

+

+If startoffset is negative or greater than the length of the subject, +pcre_exec() returns PCRE_ERROR_BADOFFSET. When the starting offset is +zero, the search for a match starts at the beginning of the subject, and this +is by far the most common case. In UTF-8 or UTF-16 mode, the offset must point +to the start of a character, or the end of the subject (in UTF-32 mode, one +data unit equals one character, so all offsets are valid). Unlike the pattern +string, the subject may contain binary zeroes. +

+

+A non-zero starting offset is useful when searching for another match in the +same subject by calling pcre_exec() again after a previous success. +Setting startoffset differs from just passing over a shortened string and +setting PCRE_NOTBOL in the case of a pattern that begins with any kind of +lookbehind. For example, consider the pattern +

+  \Biss\B
+
+which finds occurrences of "iss" in the middle of words. (\B matches only if +the current position in the subject is not a word boundary.) When applied to +the string "Mississipi" the first call to pcre_exec() finds the first +occurrence. If pcre_exec() is called again with just the remainder of the +subject, namely "issipi", it does not match, because \B is always false at the +start of the subject, which is deemed to be a word boundary. However, if +pcre_exec() is passed the entire string again, but with startoffset +set to 4, it finds the second occurrence of "iss" because it is able to look +behind the starting point to discover that it is preceded by a letter. +

+

+Finding all the matches in a subject is tricky when the pattern can match an +empty string. It is possible to emulate Perl's /g behaviour by first trying the +match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and +PCRE_ANCHORED options, and then if that fails, advancing the starting offset +and trying an ordinary match again. There is some code that demonstrates how to +do this in the +pcredemo +sample program. In the most general case, you have to check to see if the +newline convention recognizes CRLF as a newline, and if so, and the current +character is CR followed by LF, advance the starting offset by two characters +instead of one. +

+

+If a non-zero starting offset is passed when the pattern is anchored, one +attempt to match at the given offset is made. This can only succeed if the +pattern does not require the match to be at the start of the subject. +

+
+How pcre_exec() returns captured substrings +
+

+In general, a pattern matches a certain portion of the subject, and in +addition, further substrings from the subject may be picked out by parts of the +pattern. Following the usage in Jeffrey Friedl's book, this is called +"capturing" in what follows, and the phrase "capturing subpattern" is used for +a fragment of a pattern that picks out a substring. PCRE supports several other +kinds of parenthesized subpattern that do not cause substrings to be captured. +

+

+Captured substrings are returned to the caller via a vector of integers whose +address is passed in ovector. The number of elements in the vector is +passed in ovecsize, which must be a non-negative number. Note: this +argument is NOT the size of ovector in bytes. +

+

+The first two-thirds of the vector is used to pass back captured substrings, +each substring using a pair of integers. The remaining third of the vector is +used as workspace by pcre_exec() while matching capturing subpatterns, +and is not available for passing back information. The number passed in +ovecsize should always be a multiple of three. If it is not, it is +rounded down. +

+

+When a match is successful, information about captured substrings is returned +in pairs of integers, starting at the beginning of ovector, and +continuing up to two-thirds of its length at the most. The first element of +each pair is set to the offset of the first character in a substring, and the +second is set to the offset of the first character after the end of a +substring. These values are always data unit offsets, even in UTF mode. They +are byte offsets in the 8-bit library, 16-bit data item offsets in the 16-bit +library, and 32-bit data item offsets in the 32-bit library. Note: they +are not character counts. +

+

+The first pair of integers, ovector[0] and ovector[1], identify the +portion of the subject string matched by the entire pattern. The next pair is +used for the first capturing subpattern, and so on. The value returned by +pcre_exec() is one more than the highest numbered pair that has been set. +For example, if two substrings have been captured, the returned value is 3. If +there are no capturing subpatterns, the return value from a successful match is +1, indicating that just the first pair of offsets has been set. +

+

+If a capturing subpattern is matched repeatedly, it is the last portion of the +string that it matched that is returned. +

+

+If the vector is too small to hold all the captured substring offsets, it is +used as far as possible (up to two-thirds of its length), and the function +returns a value of zero. If neither the actual string matched nor any captured +substrings are of interest, pcre_exec() may be called with ovector +passed as NULL and ovecsize as zero. However, if the pattern contains +back references and the ovector is not big enough to remember the related +substrings, PCRE has to get additional memory for use during matching. Thus it +is usually advisable to supply an ovector of reasonable size. +

+

+There are some cases where zero is returned (indicating vector overflow) when +in fact the vector is exactly the right size for the final match. For example, +consider the pattern +

+  (a)(?:(b)c|bd)
+
+If a vector of 6 elements (allowing for only 1 captured substring) is given +with subject string "abd", pcre_exec() will try to set the second +captured string, thereby recording a vector overflow, before failing to match +"c" and backing up to try the second alternative. The zero return, however, +does correctly indicate that the maximum number of slots (namely 2) have been +filled. In similar cases where there is temporary overflow, but the final +number of used slots is actually less than the maximum, a non-zero value is +returned. +

+

+The pcre_fullinfo() function can be used to find out how many capturing +subpatterns there are in a compiled pattern. The smallest size for +ovector that will allow for n captured substrings, in addition to +the offsets of the substring matched by the whole pattern, is (n+1)*3. +

+

+It is possible for capturing subpattern number n+1 to match some part of +the subject when subpattern n has not been used at all. For example, if +the string "abc" is matched against the pattern (a|(z))(bc) the return from the +function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this +happens, both values in the offset pairs corresponding to unused subpatterns +are set to -1. +

+

+Offset values that correspond to unused subpatterns at the end of the +expression are also set to -1. For example, if the string "abc" is matched +against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The +return from the function is 2, because the highest used capturing subpattern +number is 1, and the offsets for for the second and third capturing subpatterns +(assuming the vector is large enough, of course) are set to -1. +

+

+Note: Elements in the first two-thirds of ovector that do not +correspond to capturing parentheses in the pattern are never changed. That is, +if a pattern contains n capturing parentheses, no more than +ovector[0] to ovector[2n+1] are set by pcre_exec(). The other +elements (in the first two-thirds) retain whatever values they previously had. +

+

+Some convenience functions are provided for extracting the captured substrings +as separate strings. These are described below. +

+
+Error return values from pcre_exec() +
+

+If pcre_exec() fails, it returns a negative number. The following are +defined in the header file: +

+  PCRE_ERROR_NOMATCH        (-1)
+
+The subject string did not match the pattern. +
+  PCRE_ERROR_NULL           (-2)
+
+Either code or subject was passed as NULL, or ovector was +NULL and ovecsize was not zero. +
+  PCRE_ERROR_BADOPTION      (-3)
+
+An unrecognized bit was set in the options argument. +
+  PCRE_ERROR_BADMAGIC       (-4)
+
+PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch +the case when it is passed a junk pointer and to detect when a pattern that was +compiled in an environment of one endianness is run in an environment with the +other endianness. This is the error that PCRE gives when the magic number is +not present. +
+  PCRE_ERROR_UNKNOWN_OPCODE (-5)
+
+While running the pattern match, an unknown item was encountered in the +compiled pattern. This error could be caused by a bug in PCRE or by overwriting +of the compiled pattern. +
+  PCRE_ERROR_NOMEMORY       (-6)
+
+If a pattern contains back references, but the ovector that is passed to +pcre_exec() is not big enough to remember the referenced substrings, PCRE +gets a block of memory at the start of matching to use for this purpose. If the +call via pcre_malloc() fails, this error is given. The memory is +automatically freed at the end of matching. +

+

+This error is also given if pcre_stack_malloc() fails in +pcre_exec(). This can happen only when PCRE has been compiled with +--disable-stack-for-recursion. +

+  PCRE_ERROR_NOSUBSTRING    (-7)
+
+This error is used by the pcre_copy_substring(), +pcre_get_substring(), and pcre_get_substring_list() functions (see +below). It is never returned by pcre_exec(). +
+  PCRE_ERROR_MATCHLIMIT     (-8)
+
+The backtracking limit, as specified by the match_limit field in a +pcre_extra structure (or defaulted) was reached. See the description +above. +
+  PCRE_ERROR_CALLOUT        (-9)
+
+This error is never generated by pcre_exec() itself. It is provided for +use by callout functions that want to yield a distinctive error code. See the +pcrecallout +documentation for details. +
+  PCRE_ERROR_BADUTF8        (-10)
+
+A string that contains an invalid UTF-8 byte sequence was passed as a subject, +and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector +(ovecsize) is at least 2, the byte offset to the start of the the invalid +UTF-8 character is placed in the first element, and a reason code is placed in +the second element. The reason codes are listed in the +following section. +For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a +truncated UTF-8 character at the end of the subject (reason codes 1 to 5), +PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8. +
+  PCRE_ERROR_BADUTF8_OFFSET (-11)
+
+The UTF-8 byte sequence that was passed as a subject was checked and found to +be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of +startoffset did not point to the beginning of a UTF-8 character or the +end of the subject. +
+  PCRE_ERROR_PARTIAL        (-12)
+
+The subject string did not match, but it did match partially. See the +pcrepartial +documentation for details of partial matching. +
+  PCRE_ERROR_BADPARTIAL     (-13)
+
+This code is no longer in use. It was formerly returned when the PCRE_PARTIAL +option was used with a compiled pattern containing items that were not +supported for partial matching. From release 8.00 onwards, there are no +restrictions on partial matching. +
+  PCRE_ERROR_INTERNAL       (-14)
+
+An unexpected internal error has occurred. This error could be caused by a bug +in PCRE or by overwriting of the compiled pattern. +
+  PCRE_ERROR_BADCOUNT       (-15)
+
+This error is given if the value of the ovecsize argument is negative. +
+  PCRE_ERROR_RECURSIONLIMIT (-21)
+
+The internal recursion limit, as specified by the match_limit_recursion +field in a pcre_extra structure (or defaulted) was reached. See the +description above. +
+  PCRE_ERROR_BADNEWLINE     (-23)
+
+An invalid combination of PCRE_NEWLINE_xxx options was given. +
+  PCRE_ERROR_BADOFFSET      (-24)
+
+The value of startoffset was negative or greater than the length of the +subject, that is, the value in length. +
+  PCRE_ERROR_SHORTUTF8      (-25)
+
+This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string +ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set. +Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in +fact sufficient to detect this case, but this special error code for +PCRE_PARTIAL_HARD precedes the implementation of returned information; it is +retained for backwards compatibility. +
+  PCRE_ERROR_RECURSELOOP    (-26)
+
+This error is returned when pcre_exec() detects a recursion loop within +the pattern. Specifically, it means that either the whole pattern or a +subpattern has been called recursively for the second time at the same position +in the subject string. Some simple patterns that might do this are detected and +faulted at compile time, but more complicated cases, in particular mutual +recursions between two different subpatterns, cannot be detected until run +time. +
+  PCRE_ERROR_JIT_STACKLIMIT (-27)
+
+This error is returned when a pattern that was successfully studied using a +JIT compile option is being matched, but the memory available for the +just-in-time processing stack is not large enough. See the +pcrejit +documentation for more details. +
+  PCRE_ERROR_BADMODE        (-28)
+
+This error is given if a pattern that was compiled by the 8-bit library is +passed to a 16-bit or 32-bit library function, or vice versa. +
+  PCRE_ERROR_BADENDIANNESS  (-29)
+
+This error is given if a pattern that was compiled and saved is reloaded on a +host with different endianness. The utility function +pcre_pattern_to_host_byte_order() can be used to convert such a pattern +so that it runs on the new host. +
+  PCRE_ERROR_JIT_BADOPTION
+
+This error is returned when a pattern that was successfully studied using a JIT +compile option is being matched, but the matching mode (partial or complete +match) does not correspond to any JIT compilation mode. When the JIT fast path +function is used, this error may be also given for invalid options. See the +pcrejit +documentation for more details. +
+  PCRE_ERROR_BADLENGTH      (-32)
+
+This error is given if pcre_exec() is called with a negative value for +the length argument. +

+

+Error numbers -16 to -20, -22, and 30 are not used by pcre_exec(). +

+
+Reason codes for invalid UTF-8 strings +
+

+This section applies only to the 8-bit library. The corresponding information +for the 16-bit and 32-bit libraries is given in the +pcre16 +and +pcre32 +pages. +

+

+When pcre_exec() returns either PCRE_ERROR_BADUTF8 or +PCRE_ERROR_SHORTUTF8, and the size of the output vector (ovecsize) is at +least 2, the offset of the start of the invalid UTF-8 character is placed in +the first output vector element (ovector[0]) and a reason code is placed +in the second element (ovector[1]). The reason codes are given names in +the pcre.h header file: +

+  PCRE_UTF8_ERR1
+  PCRE_UTF8_ERR2
+  PCRE_UTF8_ERR3
+  PCRE_UTF8_ERR4
+  PCRE_UTF8_ERR5
+
+The string ends with a truncated UTF-8 character; the code specifies how many +bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be +no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279) +allows for up to 6 bytes, and this is checked first; hence the possibility of +4 or 5 missing bytes. +
+  PCRE_UTF8_ERR6
+  PCRE_UTF8_ERR7
+  PCRE_UTF8_ERR8
+  PCRE_UTF8_ERR9
+  PCRE_UTF8_ERR10
+
+The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the +character do not have the binary value 0b10 (that is, either the most +significant bit is 0, or the next bit is 1). +
+  PCRE_UTF8_ERR11
+  PCRE_UTF8_ERR12
+
+A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long; +these code points are excluded by RFC 3629. +
+  PCRE_UTF8_ERR13
+
+A 4-byte character has a value greater than 0x10fff; these code points are +excluded by RFC 3629. +
+  PCRE_UTF8_ERR14
+
+A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of +code points are reserved by RFC 3629 for use with UTF-16, and so are excluded +from UTF-8. +
+  PCRE_UTF8_ERR15
+  PCRE_UTF8_ERR16
+  PCRE_UTF8_ERR17
+  PCRE_UTF8_ERR18
+  PCRE_UTF8_ERR19
+
+A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a +value that can be represented by fewer bytes, which is invalid. For example, +the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just +one byte. +
+  PCRE_UTF8_ERR20
+
+The two most significant bits of the first byte of a character have the binary +value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a +byte can only validly occur as the second or subsequent byte of a multi-byte +character. +
+  PCRE_UTF8_ERR21
+
+The first byte of a character has the value 0xfe or 0xff. These values can +never occur in a valid UTF-8 string. +
+  PCRE_UTF8_ERR22
+
+This error code was formerly used when the presence of a so-called +"non-character" caused an error. Unicode corrigendum #9 makes it clear that +such characters should not cause a string to be rejected, and so this code is +no longer in use and is never returned. +

+
EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+

+int pcre_copy_substring(const char *subject, int *ovector, + int stringcount, int stringnumber, char *buffer, + int buffersize); +
+
+int pcre_get_substring(const char *subject, int *ovector, + int stringcount, int stringnumber, + const char **stringptr); +
+
+int pcre_get_substring_list(const char *subject, + int *ovector, int stringcount, const char ***listptr); +

+

+Captured substrings can be accessed directly by using the offsets returned by +pcre_exec() in ovector. For convenience, the functions +pcre_copy_substring(), pcre_get_substring(), and +pcre_get_substring_list() are provided for extracting captured substrings +as new, separate, zero-terminated strings. These functions identify substrings +by number. The next section describes functions for extracting named +substrings. +

+

+A substring that contains a binary zero is correctly extracted and has a +further zero added on the end, but the result is not, of course, a C string. +However, you can process such a string by referring to the length that is +returned by pcre_copy_substring() and pcre_get_substring(). +Unfortunately, the interface to pcre_get_substring_list() is not adequate +for handling strings containing binary zeros, because the end of the final +string is not independently indicated. +

+

+The first three arguments are the same for all three of these functions: +subject is the subject string that has just been successfully matched, +ovector is a pointer to the vector of integer offsets that was passed to +pcre_exec(), and stringcount is the number of substrings that were +captured by the match, including the substring that matched the entire regular +expression. This is the value returned by pcre_exec() if it is greater +than zero. If pcre_exec() returned zero, indicating that it ran out of +space in ovector, the value passed as stringcount should be the +number of elements in the vector divided by three. +

+

+The functions pcre_copy_substring() and pcre_get_substring() +extract a single substring, whose number is given as stringnumber. A +value of zero extracts the substring that matched the entire pattern, whereas +higher values extract the captured substrings. For pcre_copy_substring(), +the string is placed in buffer, whose length is given by +buffersize, while for pcre_get_substring() a new block of memory is +obtained via pcre_malloc, and its address is returned via +stringptr. The yield of the function is the length of the string, not +including the terminating zero, or one of these error codes: +

+  PCRE_ERROR_NOMEMORY       (-6)
+
+The buffer was too small for pcre_copy_substring(), or the attempt to get +memory failed for pcre_get_substring(). +
+  PCRE_ERROR_NOSUBSTRING    (-7)
+
+There is no substring whose number is stringnumber. +

+

+The pcre_get_substring_list() function extracts all available substrings +and builds a list of pointers to them. All this is done in a single block of +memory that is obtained via pcre_malloc. The address of the memory block +is returned via listptr, which is also the start of the list of string +pointers. The end of the list is marked by a NULL pointer. The yield of the +function is zero if all went well, or the error code +

+  PCRE_ERROR_NOMEMORY       (-6)
+
+if the attempt to get the memory block failed. +

+

+When any of these functions encounter a substring that is unset, which can +happen when capturing subpattern number n+1 matches some part of the +subject, but subpattern n has not been used at all, they return an empty +string. This can be distinguished from a genuine zero-length substring by +inspecting the appropriate offset in ovector, which is negative for unset +substrings. +

+

+The two convenience functions pcre_free_substring() and +pcre_free_substring_list() can be used to free the memory returned by +a previous call of pcre_get_substring() or +pcre_get_substring_list(), respectively. They do nothing more than call +the function pointed to by pcre_free, which of course could be called +directly from a C program. However, PCRE is used in some situations where it is +linked via a special interface to another programming language that cannot use +pcre_free directly; it is for these cases that the functions are +provided. +

+
EXTRACTING CAPTURED SUBSTRINGS BY NAME
+

+int pcre_get_stringnumber(const pcre *code, + const char *name); +
+
+int pcre_copy_named_substring(const pcre *code, + const char *subject, int *ovector, + int stringcount, const char *stringname, + char *buffer, int buffersize); +
+
+int pcre_get_named_substring(const pcre *code, + const char *subject, int *ovector, + int stringcount, const char *stringname, + const char **stringptr); +

+

+To extract a substring by name, you first have to find associated number. +For example, for this pattern +

+  (a+)b(?<xxx>\d+)...
+
+the number of the subpattern called "xxx" is 2. If the name is known to be +unique (PCRE_DUPNAMES was not set), you can find the number from the name by +calling pcre_get_stringnumber(). The first argument is the compiled +pattern, and the second is the name. The yield of the function is the +subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of +that name. +

+

+Given the number, you can extract the substring directly, or use one of the +functions described in the previous section. For convenience, there are also +two functions that do the whole job. +

+

+Most of the arguments of pcre_copy_named_substring() and +pcre_get_named_substring() are the same as those for the similarly named +functions that extract by number. As these are described in the previous +section, they are not re-described here. There are just two differences: +

+

+First, instead of a substring number, a substring name is given. Second, there +is an extra argument, given at the start, which is a pointer to the compiled +pattern. This is needed in order to gain access to the name-to-number +translation table. +

+

+These functions call pcre_get_stringnumber(), and if it succeeds, they +then call pcre_copy_substring() or pcre_get_substring(), as +appropriate. NOTE: If PCRE_DUPNAMES is set and there are duplicate names, +the behaviour may not be what you want (see the next section). +

+

+Warning: If the pattern uses the (?| feature to set up multiple +subpatterns with the same number, as described in the +section on duplicate subpattern numbers +in the +pcrepattern +page, you cannot use names to distinguish the different subpatterns, because +names are not included in the compiled code. The matching process uses only +numbers. For this reason, the use of different names for subpatterns of the +same number causes an error at compile time. +

+
DUPLICATE SUBPATTERN NAMES
+

+int pcre_get_stringtable_entries(const pcre *code, + const char *name, char **first, char **last); +

+

+When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns +are not required to be unique. (Duplicate names are always allowed for +subpatterns with the same number, created by using the (?| feature. Indeed, if +such subpatterns are named, they are required to use the same names.) +

+

+Normally, patterns with duplicate names are such that in any one match, only +one of the named subpatterns participates. An example is shown in the +pcrepattern +documentation. +

+

+When duplicates are present, pcre_copy_named_substring() and +pcre_get_named_substring() return the first substring corresponding to +the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is +returned; no data is returned. The pcre_get_stringnumber() function +returns one of the numbers that are associated with the name, but it is not +defined which it is. +

+

+If you want to get full details of all captured substrings for a given name, +you must use the pcre_get_stringtable_entries() function. The first +argument is the compiled pattern, and the second is the name. The third and +fourth are pointers to variables which are updated by the function. After it +has run, they point to the first and last entries in the name-to-number table +for the given name. The function itself returns the length of each entry, or +PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is +described above in the section entitled Information about a pattern +above. +Given all the relevant entries for the name, you can extract each of their +numbers, and hence the captured data, if any. +

+
FINDING ALL POSSIBLE MATCHES
+

+The traditional matching function uses a similar algorithm to Perl, which stops +when it finds the first match, starting at a given point in the subject. If you +want to find all possible matches, or the longest possible match, consider +using the alternative matching function (see below) instead. If you cannot use +the alternative function, but still need to find all possible matches, you +can kludge it up by making use of the callout facility, which is described in +the +pcrecallout +documentation. +

+

+What you have to do is to insert a callout right at the end of the pattern. +When your callout function is called, extract and save the current matched +substring. Then return 1, which forces pcre_exec() to backtrack and try +other alternatives. Ultimately, when it runs out of matches, pcre_exec() +will yield PCRE_ERROR_NOMATCH. +

+
OBTAINING AN ESTIMATE OF STACK USAGE
+

+Matching certain patterns using pcre_exec() can use a lot of process +stack, which in certain environments can be rather limited in size. Some users +find it helpful to have an estimate of the amount of stack that is used by +pcre_exec(), to help them set recursion limits, as described in the +pcrestack +documentation. The estimate that is output by pcretest when called with +the -m and -C options is obtained by calling pcre_exec with +the values NULL, NULL, NULL, -999, and -999 for its first five arguments. +

+

+Normally, if its first argument is NULL, pcre_exec() immediately returns +the negative error code PCRE_ERROR_NULL, but with this special combination of +arguments, it returns instead a negative number whose absolute value is the +approximate stack frame size in bytes. (A negative number is used so that it is +clear that no match has happened.) The value is approximate because in some +cases, recursive calls to pcre_exec() occur when there are one or two +additional variables on the stack. +

+

+If PCRE has been compiled to use the heap instead of the stack for recursion, +the value returned is the size of each block that is obtained from the heap. +

+
MATCHING A PATTERN: THE ALTERNATIVE FUNCTION
+

+int pcre_dfa_exec(const pcre *code, const pcre_extra *extra, + const char *subject, int length, int startoffset, + int options, int *ovector, int ovecsize, + int *workspace, int wscount); +

+

+The function pcre_dfa_exec() is called to match a subject string against +a compiled pattern, using a matching algorithm that scans the subject string +just once, and does not backtrack. This has different characteristics to the +normal algorithm, and is not compatible with Perl. Some of the features of PCRE +patterns are not supported. Nevertheless, there are times when this kind of +matching can be useful. For a discussion of the two matching algorithms, and a +list of features that pcre_dfa_exec() does not support, see the +pcrematching +documentation. +

+

+The arguments for the pcre_dfa_exec() function are the same as for +pcre_exec(), plus two extras. The ovector argument is used in a +different way, and this is described below. The other common arguments are used +in the same way as for pcre_exec(), so their description is not repeated +here. +

+

+The two additional arguments provide workspace for the function. The workspace +vector should contain at least 20 elements. It is used for keeping track of +multiple paths through the pattern tree. More workspace will be needed for +patterns and subjects where there are a lot of potential matches. +

+

+Here is an example of a simple call to pcre_dfa_exec(): +

+  int rc;
+  int ovector[10];
+  int wspace[20];
+  rc = pcre_dfa_exec(
+    re,             /* result of pcre_compile() */
+    NULL,           /* we didn't study the pattern */
+    "some string",  /* the subject string */
+    11,             /* the length of the subject string */
+    0,              /* start at offset 0 in the subject */
+    0,              /* default options */
+    ovector,        /* vector of integers for substring information */
+    10,             /* number of elements (NOT size in bytes) */
+    wspace,         /* working space vector */
+    20);            /* number of elements (NOT size in bytes) */
+
+

+
+Option bits for pcre_dfa_exec() +
+

+The unused bits of the options argument for pcre_dfa_exec() must be +zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx, +PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, +PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE, +PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. +All but the last four of these are exactly the same as for pcre_exec(), +so their description is not repeated here. +

+  PCRE_PARTIAL_HARD
+  PCRE_PARTIAL_SOFT
+
+These have the same general effect as they do for pcre_exec(), but the +details are slightly different. When PCRE_PARTIAL_HARD is set for +pcre_dfa_exec(), it returns PCRE_ERROR_PARTIAL if the end of the subject +is reached and there is still at least one matching possibility that requires +additional characters. This happens even if some complete matches have also +been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH +is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached, +there have been no complete matches, but there is still at least one matching +possibility. The portion of the string that was inspected when the longest +partial match was found is set as the first matching string in both cases. +There is a more detailed discussion of partial and multi-segment matching, with +examples, in the +pcrepartial +documentation. +
+  PCRE_DFA_SHORTEST
+
+Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as +soon as it has found one match. Because of the way the alternative algorithm +works, this is necessarily the shortest possible match at the first possible +matching point in the subject string. +
+  PCRE_DFA_RESTART
+
+When pcre_dfa_exec() returns a partial match, it is possible to call it +again, with additional subject characters, and have it continue with the same +match. The PCRE_DFA_RESTART option requests this action; when it is set, the +workspace and wscount options must reference the same vector as +before because data about the match so far is left in them after a partial +match. There is more discussion of this facility in the +pcrepartial +documentation. +

+
+Successful returns from pcre_dfa_exec() +
+

+When pcre_dfa_exec() succeeds, it may have matched more than one +substring in the subject. Note, however, that all the matches from one run of +the function start at the same point in the subject. The shorter matches are +all initial substrings of the longer matches. For example, if the pattern +

+  <.*>
+
+is matched against the string +
+  This is <something> <something else> <something further> no more
+
+the three matched strings are +
+  <something>
+  <something> <something else>
+  <something> <something else> <something further>
+
+On success, the yield of the function is a number greater than zero, which is +the number of matched substrings. The substrings themselves are returned in +ovector. Each string uses two elements; the first is the offset to the +start, and the second is the offset to the end. In fact, all the strings have +the same start offset. (Space could have been saved by giving this only once, +but it was decided to retain some compatibility with the way pcre_exec() +returns data, even though the meaning of the strings is different.) +

+

+The strings are returned in reverse order of length; that is, the longest +matching string is given first. If there were too many matches to fit into +ovector, the yield of the function is zero, and the vector is filled with +the longest matches. Unlike pcre_exec(), pcre_dfa_exec() can use +the entire ovector for returning matched strings. +

+

+NOTE: PCRE's "auto-possessification" optimization usually applies to character +repeats at the end of a pattern (as well as internally). For example, the +pattern "a\d+" is compiled as if it were "a\d++" because there is no point +even considering the possibility of backtracking into the repeated digits. For +DFA matching, this means that only one possible match is found. If you really +do want multiple matches in such cases, either use an ungreedy repeat +("a\d+?") or set the PCRE_NO_AUTO_POSSESS option when compiling. +

+
+Error returns from pcre_dfa_exec() +
+

+The pcre_dfa_exec() function returns a negative number when it fails. +Many of the errors are the same as for pcre_exec(), and these are +described +above. +There are in addition the following errors that are specific to +pcre_dfa_exec(): +

+  PCRE_ERROR_DFA_UITEM      (-16)
+
+This return is given if pcre_dfa_exec() encounters an item in the pattern +that it does not support, for instance, the use of \C or a back reference. +
+  PCRE_ERROR_DFA_UCOND      (-17)
+
+This return is given if pcre_dfa_exec() encounters a condition item that +uses a back reference for the condition, or a test for recursion in a specific +group. These are not supported. +
+  PCRE_ERROR_DFA_UMLIMIT    (-18)
+
+This return is given if pcre_dfa_exec() is called with an extra +block that contains a setting of the match_limit or +match_limit_recursion fields. This is not supported (these fields are +meaningless for DFA matching). +
+  PCRE_ERROR_DFA_WSSIZE     (-19)
+
+This return is given if pcre_dfa_exec() runs out of space in the +workspace vector. +
+  PCRE_ERROR_DFA_RECURSE    (-20)
+
+When a recursive subpattern is processed, the matching function calls itself +recursively, using private vectors for ovector and workspace. This +error is given if the output vector is not large enough. This should be +extremely rare, as a vector of size 1000 is used. +
+  PCRE_ERROR_DFA_BADRESTART (-30)
+
+When pcre_dfa_exec() is called with the PCRE_DFA_RESTART option, +some plausibility checks are made on the contents of the workspace, which +should contain data about the previous partial match. If any of these checks +fail, this error is given. +

+
SEE ALSO
+

+pcre16(3), pcre32(3), pcrebuild(3), pcrecallout(3), +pcrecpp(3)(3), pcrematching(3), pcrepartial(3), +pcreposix(3), pcreprecompile(3), pcresample(3), +pcrestack(3). +

+
AUTHOR
+

+Philip Hazel +
+University Computing Service +
+Cambridge CB2 3QH, England. +
+

+
REVISION
+

+Last updated: 09 February 2014 +
+Copyright © 1997-2014 University of Cambridge. +
+

+Return to the PCRE index page. +

diff --git a/doc/html/pcrebuild.html b/doc/html/pcrebuild.html new file mode 100644 index 0000000..03c8cbe --- /dev/null +++ b/doc/html/pcrebuild.html @@ -0,0 +1,534 @@ + + +pcrebuild specification + + +

pcrebuild man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+

+
BUILDING PCRE
+

+PCRE is distributed with a configure script that can be used to build the +library in Unix-like environments using the applications known as Autotools. +Also in the distribution are files to support building using CMake +instead of configure. The text file +README +contains general information about building with Autotools (some of which is +repeated below), and also has some comments about building on various operating +systems. There is a lot more information about building PCRE without using +Autotools (including information about using CMake and building "by +hand") in the text file called +NON-AUTOTOOLS-BUILD. +You should consult this file as well as the +README +file if you are building in a non-Unix-like environment. +

+
PCRE BUILD-TIME OPTIONS
+

+The rest of this document describes the optional features of PCRE that can be +selected when the library is compiled. It assumes use of the configure +script, where the optional features are selected or deselected by providing +options to configure before running the make command. However, the +same options can be selected in both Unix-like and non-Unix-like environments +using the GUI facility of cmake-gui if you are using CMake instead +of configure to build PCRE. +

+

+If you are not using Autotools or CMake, option selection can be done by +editing the config.h file, or by passing parameter settings to the +compiler, as described in +NON-AUTOTOOLS-BUILD. +

+

+The complete list of options for configure (which includes the standard +ones such as the selection of the installation directory) can be obtained by +running +

+  ./configure --help
+
+The following sections include descriptions of options whose names begin with +--enable or --disable. These settings specify changes to the defaults for the +configure command. Because of the way that configure works, +--enable and --disable always come in pairs, so the complementary option always +exists as well, but as it specifies the default, it is not described. +

+
BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
+

+By default, a library called libpcre is built, containing functions that +take string arguments contained in vectors of bytes, either as single-byte +characters, or interpreted as UTF-8 strings. You can also build a separate +library, called libpcre16, in which strings are contained in vectors of +16-bit data units and interpreted either as single-unit characters or UTF-16 +strings, by adding +

+  --enable-pcre16
+
+to the configure command. You can also build yet another separate +library, called libpcre32, in which strings are contained in vectors of +32-bit data units and interpreted either as single-unit characters or UTF-32 +strings, by adding +
+  --enable-pcre32
+
+to the configure command. If you do not want the 8-bit library, add +
+  --disable-pcre8
+
+as well. At least one of the three libraries must be built. Note that the C++ +and POSIX wrappers are for the 8-bit library only, and that pcregrep is +an 8-bit program. None of these are built if you select only the 16-bit or +32-bit libraries. +

+
BUILDING SHARED AND STATIC LIBRARIES
+

+The Autotools PCRE building process uses libtool to build both shared and +static libraries by default. You can suppress one of these by adding one of +

+  --disable-shared
+  --disable-static
+
+to the configure command, as required. +

+
C++ SUPPORT
+

+By default, if the 8-bit library is being built, the configure script +will search for a C++ compiler and C++ header files. If it finds them, it +automatically builds the C++ wrapper library (which supports only 8-bit +strings). You can disable this by adding +

+  --disable-cpp
+
+to the configure command. +

+
UTF-8, UTF-16 AND UTF-32 SUPPORT
+

+To build PCRE with support for UTF Unicode character strings, add +

+  --enable-utf
+
+to the configure command. This setting applies to all three libraries, +adding support for UTF-8 to the 8-bit library, support for UTF-16 to the 16-bit +library, and support for UTF-32 to the to the 32-bit library. There are no +separate options for enabling UTF-8, UTF-16 and UTF-32 independently because +that would allow ridiculous settings such as requesting UTF-16 support while +building only the 8-bit library. It is not possible to build one library with +UTF support and another without in the same configuration. (For backwards +compatibility, --enable-utf8 is a synonym of --enable-utf.) +

+

+Of itself, this setting does not make PCRE treat strings as UTF-8, UTF-16 or +UTF-32. As well as compiling PCRE with this option, you also have have to set +the PCRE_UTF8, PCRE_UTF16 or PCRE_UTF32 option (as appropriate) when you call +one of the pattern compiling functions. +

+

+If you set --enable-utf when compiling in an EBCDIC environment, PCRE expects +its input to be either ASCII or UTF-8 (depending on the run-time option). It is +not possible to support both EBCDIC and UTF-8 codes in the same version of the +library. Consequently, --enable-utf and --enable-ebcdic are mutually +exclusive. +

+
UNICODE CHARACTER PROPERTY SUPPORT
+

+UTF support allows the libraries to process character codepoints up to 0x10ffff +in the strings that they handle. On its own, however, it does not provide any +facilities for accessing the properties of such characters. If you want to be +able to use the pattern escapes \P, \p, and \X, which refer to Unicode +character properties, you must add +

+  --enable-unicode-properties
+
+to the configure command. This implies UTF support, even if you have +not explicitly requested it. +

+

+Including Unicode property support adds around 30K of tables to the PCRE +library. Only the general category properties such as Lu and Nd are +supported. Details are given in the +pcrepattern +documentation. +

+
JUST-IN-TIME COMPILER SUPPORT
+

+Just-in-time compiler support is included in the build by specifying +

+  --enable-jit
+
+This support is available only for certain hardware architectures. If this +option is set for an unsupported architecture, a compile time error occurs. +See the +pcrejit +documentation for a discussion of JIT usage. When JIT support is enabled, +pcregrep automatically makes use of it, unless you add +
+  --disable-pcregrep-jit
+
+to the "configure" command. +

+
CODE VALUE OF NEWLINE
+

+By default, PCRE interprets the linefeed (LF) character as indicating the end +of a line. This is the normal newline character on Unix-like systems. You can +compile PCRE to use carriage return (CR) instead, by adding +

+  --enable-newline-is-cr
+
+to the configure command. There is also a --enable-newline-is-lf option, +which explicitly specifies linefeed as the newline character. +
+
+Alternatively, you can specify that line endings are to be indicated by the two +character sequence CRLF. If you want this, add +
+  --enable-newline-is-crlf
+
+to the configure command. There is a fourth option, specified by +
+  --enable-newline-is-anycrlf
+
+which causes PCRE to recognize any of the three sequences CR, LF, or CRLF as +indicating a line ending. Finally, a fifth option, specified by +
+  --enable-newline-is-any
+
+causes PCRE to recognize any Unicode newline sequence. +

+

+Whatever line ending convention is selected when PCRE is built can be +overridden when the library functions are called. At build time it is +conventional to use the standard for your operating system. +

+
WHAT \R MATCHES
+

+By default, the sequence \R in a pattern matches any Unicode newline sequence, +whatever has been selected as the line ending sequence. If you specify +

+  --enable-bsr-anycrlf
+
+the default is changed so that \R matches only CR, LF, or CRLF. Whatever is +selected when PCRE is built can be overridden when the library functions are +called. +

+
POSIX MALLOC USAGE
+

+When the 8-bit library is called through the POSIX interface (see the +pcreposix +documentation), additional working storage is required for holding the pointers +to capturing substrings, because PCRE requires three integers per substring, +whereas the POSIX interface provides only two. If the number of expected +substrings is small, the wrapper function uses space on the stack, because this +is faster than using malloc() for each call. The default threshold above +which the stack is no longer used is 10; it can be changed by adding a setting +such as +

+  --with-posix-malloc-threshold=20
+
+to the configure command. +

+
HANDLING VERY LARGE PATTERNS
+

+Within a compiled pattern, offset values are used to point from one part to +another (for example, from an opening parenthesis to an alternation +metacharacter). By default, in the 8-bit and 16-bit libraries, two-byte values +are used for these offsets, leading to a maximum size for a compiled pattern of +around 64K. This is sufficient to handle all but the most gigantic patterns. +Nevertheless, some people do want to process truly enormous patterns, so it is +possible to compile PCRE to use three-byte or four-byte offsets by adding a +setting such as +

+  --with-link-size=3
+
+to the configure command. The value given must be 2, 3, or 4. For the +16-bit library, a value of 3 is rounded up to 4. In these libraries, using +longer offsets slows down the operation of PCRE because it has to load +additional data when handling them. For the 32-bit library the value is always +4 and cannot be overridden; the value of --with-link-size is ignored. +

+
AVOIDING EXCESSIVE STACK USAGE
+

+When matching with the pcre_exec() function, PCRE implements backtracking +by making recursive calls to an internal function called match(). In +environments where the size of the stack is limited, this can severely limit +PCRE's operation. (The Unix environment does not usually suffer from this +problem, but it may sometimes be necessary to increase the maximum stack size. +There is a discussion in the +pcrestack +documentation.) An alternative approach to recursion that uses memory from the +heap to remember data, instead of using recursive function calls, has been +implemented to work round the problem of limited stack size. If you want to +build a version of PCRE that works this way, add +

+  --disable-stack-for-recursion
+
+to the configure command. With this configuration, PCRE will use the +pcre_stack_malloc and pcre_stack_free variables to call memory +management functions. By default these point to malloc() and +free(), but you can replace the pointers so that your own functions are +used instead. +

+

+Separate functions are provided rather than using pcre_malloc and +pcre_free because the usage is very predictable: the block sizes +requested are always the same, and the blocks are always freed in reverse +order. A calling program might be able to implement optimized functions that +perform better than malloc() and free(). PCRE runs noticeably more +slowly when built in this way. This option affects only the pcre_exec() +function; it is not relevant for pcre_dfa_exec(). +

+
LIMITING PCRE RESOURCE USAGE
+

+Internally, PCRE has a function called match(), which it calls repeatedly +(sometimes recursively) when matching a pattern with the pcre_exec() +function. By controlling the maximum number of times this function may be +called during a single matching operation, a limit can be placed on the +resources used by a single call to pcre_exec(). The limit can be changed +at run time, as described in the +pcreapi +documentation. The default is 10 million, but this can be changed by adding a +setting such as +

+  --with-match-limit=500000
+
+to the configure command. This setting has no effect on the +pcre_dfa_exec() matching function. +

+

+In some environments it is desirable to limit the depth of recursive calls of +match() more strictly than the total number of calls, in order to +restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion +is specified) that is used. A second limit controls this; it defaults to the +value that is set for --with-match-limit, which imposes no additional +constraints. However, you can set a lower limit by adding, for example, +

+  --with-match-limit-recursion=10000
+
+to the configure command. This value can also be overridden at run time. +

+
CREATING CHARACTER TABLES AT BUILD TIME
+

+PCRE uses fixed tables for processing characters whose code values are less +than 256. By default, PCRE is built with a set of tables that are distributed +in the file pcre_chartables.c.dist. These tables are for ASCII codes +only. If you add +

+  --enable-rebuild-chartables
+
+to the configure command, the distributed tables are no longer used. +Instead, a program called dftables is compiled and run. This outputs the +source for new set of tables, created in the default locale of your C run-time +system. (This method of replacing the tables does not work if you are cross +compiling, because dftables is run on the local host. If you need to +create alternative tables when cross compiling, you will have to do so "by +hand".) +

+
USING EBCDIC CODE
+

+PCRE assumes by default that it will run in an environment where the character +code is ASCII (or Unicode, which is a superset of ASCII). This is the case for +most computer operating systems. PCRE can, however, be compiled to run in an +EBCDIC environment by adding +

+  --enable-ebcdic
+
+to the configure command. This setting implies +--enable-rebuild-chartables. You should only use it if you know that you are in +an EBCDIC environment (for example, an IBM mainframe operating system). The +--enable-ebcdic option is incompatible with --enable-utf. +

+

+The EBCDIC character that corresponds to an ASCII LF is assumed to have the +value 0x15 by default. However, in some EBCDIC environments, 0x25 is used. In +such an environment you should use +

+  --enable-ebcdic-nl25
+
+as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR has the +same value as in ASCII, namely, 0x0d. Whichever of 0x15 and 0x25 is not +chosen as LF is made to correspond to the Unicode NEL character (which, in +Unicode, is 0x85). +

+

+The options that select newline behaviour, such as --enable-newline-is-cr, +and equivalent run-time options, refer to these character values in an EBCDIC +environment. +

+
PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
+

+By default, pcregrep reads all files as plain text. You can build it so +that it recognizes files whose names end in .gz or .bz2, and reads +them with libz or libbz2, respectively, by adding one or both of +

+  --enable-pcregrep-libz
+  --enable-pcregrep-libbz2
+
+to the configure command. These options naturally require that the +relevant libraries are installed on your system. Configuration will fail if +they are not. +

+
PCREGREP BUFFER SIZE
+

+pcregrep uses an internal buffer to hold a "window" on the file it is +scanning, in order to be able to output "before" and "after" lines when it +finds a match. The size of the buffer is controlled by a parameter whose +default value is 20K. The buffer itself is three times this size, but because +of the way it is used for holding "before" lines, the longest line that is +guaranteed to be processable is the parameter size. You can change the default +parameter value by adding, for example, +

+  --with-pcregrep-bufsize=50K
+
+to the configure command. The caller of \fPpcregrep\fP can, however, +override this value by specifying a run-time option. +

+
PCRETEST OPTION FOR LIBREADLINE SUPPORT
+

+If you add +

+  --enable-pcretest-libreadline
+
+to the configure command, pcretest is linked with the +libreadline library, and when its input is from a terminal, it reads it +using the readline() function. This provides line-editing and history +facilities. Note that libreadline is GPL-licensed, so if you distribute a +binary of pcretest linked in this way, there may be licensing issues. +

+

+Setting this option causes the -lreadline option to be added to the +pcretest build. In many operating environments with a sytem-installed +libreadline this is sufficient. However, in some environments (e.g. +if an unmodified distribution version of readline is in use), some extra +configuration may be necessary. The INSTALL file for libreadline says +this: +

+  "Readline uses the termcap functions, but does not link with the
+  termcap or curses library itself, allowing applications which link
+  with readline the to choose an appropriate library."
+
+If your environment has not been set up so that an appropriate library is +automatically included, you may need to add something like +
+  LIBS="-ncurses"
+
+immediately before the configure command. +

+
DEBUGGING WITH VALGRIND SUPPORT
+

+By adding the +

+  --enable-valgrind
+
+option to to the configure command, PCRE will use valgrind annotations +to mark certain memory regions as unaddressable. This allows it to detect +invalid memory accesses, and is mostly useful for debugging PCRE itself. +

+
CODE COVERAGE REPORTING
+

+If your C compiler is gcc, you can build a version of PCRE that can generate a +code coverage report for its test suite. To enable this, you must install +lcov version 1.6 or above. Then specify +

+  --enable-coverage
+
+to the configure command and build PCRE in the usual way. +

+

+Note that using ccache (a caching C compiler) is incompatible with code +coverage reporting. If you have configured ccache to run automatically +on your system, you must set the environment variable +

+  CCACHE_DISABLE=1
+
+before running make to build PCRE, so that ccache is not used. +

+

+When --enable-coverage is used, the following addition targets are added to the +Makefile: +

+  make coverage
+
+This creates a fresh coverage report for the PCRE test suite. It is equivalent +to running "make coverage-reset", "make coverage-baseline", "make check", and +then "make coverage-report". +
+  make coverage-reset
+
+This zeroes the coverage counters, but does nothing else. +
+  make coverage-baseline
+
+This captures baseline coverage information. +
+  make coverage-report
+
+This creates the coverage report. +
+  make coverage-clean-report
+
+This removes the generated coverage report without cleaning the coverage data +itself. +
+  make coverage-clean-data
+
+This removes the captured coverage data without removing the coverage files +created at compile time (*.gcno). +
+  make coverage-clean
+
+This cleans all coverage data including the generated coverage report. For more +information about code coverage, see the gcov and lcov +documentation. +

+
SEE ALSO
+

+pcreapi(3), pcre16, pcre32, pcre_config(3). +

+
AUTHOR
+

+Philip Hazel +
+University Computing Service +
+Cambridge CB2 3QH, England. +
+

+
REVISION
+

+Last updated: 12 May 2013 +
+Copyright © 1997-2013 University of Cambridge. +
+

+Return to the PCRE index page. +

diff --git a/doc/html/pcrecallout.html b/doc/html/pcrecallout.html new file mode 100644 index 0000000..53a937f --- /dev/null +++ b/doc/html/pcrecallout.html @@ -0,0 +1,286 @@ + + +pcrecallout specification + + +

pcrecallout man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+

+
SYNOPSIS
+

+#include <pcre.h> +

+

+int (*pcre_callout)(pcre_callout_block *); +

+

+int (*pcre16_callout)(pcre16_callout_block *); +

+

+int (*pcre32_callout)(pcre32_callout_block *); +

+
DESCRIPTION
+

+PCRE provides a feature called "callout", which is a means of temporarily +passing control to the caller of PCRE in the middle of pattern matching. The +caller of PCRE provides an external function by putting its entry point in the +global variable pcre_callout (pcre16_callout for the 16-bit +library, pcre32_callout for the 32-bit library). By default, this +variable contains NULL, which disables all calling out. +

+

+Within a regular expression, (?C) indicates the points at which the external +function is to be called. Different callout points can be identified by putting +a number less than 256 after the letter C. The default value is zero. +For example, this pattern has two callout points: +

+  (?C1)abc(?C2)def
+
+If the PCRE_AUTO_CALLOUT option bit is set when a pattern is compiled, PCRE +automatically inserts callouts, all with number 255, before each item in the +pattern. For example, if PCRE_AUTO_CALLOUT is used with the pattern +
+  A(\d{2}|--)
+
+it is processed as if it were +
+
+(?C255)A(?C255)((?C255)\d{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255) +
+
+Notice that there is a callout before and after each parenthesis and +alternation bar. If the pattern contains a conditional group whose condition is +an assertion, an automatic callout is inserted immediately before the +condition. Such a callout may also be inserted explicitly, for example: +
+  (?(?C9)(?=a)ab|de)
+
+This applies only to assertion conditions (because they are themselves +independent groups). +

+

+Automatic callouts can be used for tracking the progress of pattern matching. +The +pcretest +program has a pattern qualifier (/C) that sets automatic callouts; when it is +used, the output indicates how the pattern is being matched. This is useful +information when you are trying to optimize the performance of a particular +pattern. +

+
MISSING CALLOUTS
+

+You should be aware that, because of optimizations in the way PCRE compiles and +matches patterns, callouts sometimes do not happen exactly as you might expect. +

+

+At compile time, PCRE "auto-possessifies" repeated items when it knows that +what follows cannot be part of the repeat. For example, a+[bc] is compiled as +if it were a++[bc]. The pcretest output when this pattern is anchored and +then applied with automatic callouts to the string "aaaa" is: +

+  --->aaaa
+   +0 ^        ^
+   +1 ^        a+
+   +3 ^   ^    [bc]
+  No match
+
+This indicates that when matching [bc] fails, there is no backtracking into a+ +and therefore the callouts that would be taken for the backtracks do not occur. +You can disable the auto-possessify feature by passing PCRE_NO_AUTO_POSSESS +to pcre_compile(), or starting the pattern with (*NO_AUTO_POSSESS). If +this is done in pcretest (using the /O qualifier), the output changes to +this: +
+  --->aaaa
+   +0 ^        ^
+   +1 ^        a+
+   +3 ^   ^    [bc]
+   +3 ^  ^     [bc]
+   +3 ^ ^      [bc]
+   +3 ^^       [bc]
+  No match
+
+This time, when matching [bc] fails, the matcher backtracks into a+ and tries +again, repeatedly, until a+ itself fails. +

+

+Other optimizations that provide fast "no match" results also affect callouts. +For example, if the pattern is +

+  ab(?C4)cd
+
+PCRE knows that any matching string must contain the letter "d". If the subject +string is "abyz", the lack of "d" means that matching doesn't ever start, and +the callout is never reached. However, with "abyd", though the result is still +no match, the callout is obeyed. +

+

+If the pattern is studied, PCRE knows the minimum length of a matching string, +and will immediately give a "no match" return without actually running a match +if the subject is not long enough, or, for unanchored patterns, if it has +been scanned far enough. +

+

+You can disable these optimizations by passing the PCRE_NO_START_OPTIMIZE +option to the matching function, or by starting the pattern with +(*NO_START_OPT). This slows down the matching process, but does ensure that +callouts such as the example above are obeyed. +

+
THE CALLOUT INTERFACE
+

+During matching, when PCRE reaches a callout point, the external function +defined by pcre_callout or pcre[16|32]_callout is called (if it is +set). This applies to both normal and DFA matching. The only argument to the +callout function is a pointer to a pcre_callout or +pcre[16|32]_callout block. These structures contains the following +fields: +

+  int           version;
+  int           callout_number;
+  int          *offset_vector;
+  const char   *subject;           (8-bit version)
+  PCRE_SPTR16   subject;           (16-bit version)
+  PCRE_SPTR32   subject;           (32-bit version)
+  int           subject_length;
+  int           start_match;
+  int           current_position;
+  int           capture_top;
+  int           capture_last;
+  void         *callout_data;
+  int           pattern_position;
+  int           next_item_length;
+  const unsigned char *mark;       (8-bit version)
+  const PCRE_UCHAR16  *mark;       (16-bit version)
+  const PCRE_UCHAR32  *mark;       (32-bit version)
+
+The version field is an integer containing the version number of the +block format. The initial version was 0; the current version is 2. The version +number will change again in future if additional fields are added, but the +intention is never to remove any of the existing fields. +

+

+The callout_number field contains the number of the callout, as compiled +into the pattern (that is, the number after ?C for manual callouts, and 255 for +automatically generated callouts). +

+

+The offset_vector field is a pointer to the vector of offsets that was +passed by the caller to the matching function. When pcre_exec() or +pcre[16|32]_exec() is used, the contents can be inspected, in order to +extract substrings that have been matched so far, in the same way as for +extracting substrings after a match has completed. For the DFA matching +functions, this field is not useful. +

+

+The subject and subject_length fields contain copies of the values +that were passed to the matching function. +

+

+The start_match field normally contains the offset within the subject at +which the current match attempt started. However, if the escape sequence \K +has been encountered, this value is changed to reflect the modified starting +point. If the pattern is not anchored, the callout function may be called +several times from the same point in the pattern for different starting points +in the subject. +

+

+The current_position field contains the offset within the subject of the +current match pointer. +

+

+When the pcre_exec() or pcre[16|32]_exec() is used, the +capture_top field contains one more than the number of the highest +numbered captured substring so far. If no substrings have been captured, the +value of capture_top is one. This is always the case when the DFA +functions are used, because they do not support captured substrings. +

+

+The capture_last field contains the number of the most recently captured +substring. However, when a recursion exits, the value reverts to what it was +outside the recursion, as do the values of all captured substrings. If no +substrings have been captured, the value of capture_last is -1. This is +always the case for the DFA matching functions. +

+

+The callout_data field contains a value that is passed to a matching +function specifically so that it can be passed back in callouts. It is passed +in the callout_data field of a pcre_extra or pcre[16|32]_extra +data structure. If no such data was passed, the value of callout_data in +a callout block is NULL. There is a description of the pcre_extra +structure in the +pcreapi +documentation. +

+

+The pattern_position field is present from version 1 of the callout +structure. It contains the offset to the next item to be matched in the pattern +string. +

+

+The next_item_length field is present from version 1 of the callout +structure. It contains the length of the next item to be matched in the pattern +string. When the callout immediately precedes an alternation bar, a closing +parenthesis, or the end of the pattern, the length is zero. When the callout +precedes an opening parenthesis, the length is that of the entire subpattern. +

+

+The pattern_position and next_item_length fields are intended to +help in distinguishing between different automatic callouts, which all have the +same callout number. However, they are set for all callouts. +

+

+The mark field is present from version 2 of the callout structure. In +callouts from pcre_exec() or pcre[16|32]_exec() it contains a +pointer to the zero-terminated name of the most recently passed (*MARK), +(*PRUNE), or (*THEN) item in the match, or NULL if no such items have been +passed. Instances of (*PRUNE) or (*THEN) without a name do not obliterate a +previous (*MARK). In callouts from the DFA matching functions this field always +contains NULL. +

+
RETURN VALUES
+

+The external callout function returns an integer to PCRE. If the value is zero, +matching proceeds as normal. If the value is greater than zero, matching fails +at the current point, but the testing of other matching possibilities goes +ahead, just as if a lookahead assertion had failed. If the value is less than +zero, the match is abandoned, the matching function returns the negative value. +

+

+Negative values should normally be chosen from the set of PCRE_ERROR_xxx +values. In particular, PCRE_ERROR_NOMATCH forces a standard "no match" failure. +The error number PCRE_ERROR_CALLOUT is reserved for use by callout functions; +it will never be used by PCRE itself. +

+
AUTHOR
+

+Philip Hazel +
+University Computing Service +
+Cambridge CB2 3QH, England. +
+

+
REVISION
+

+Last updated: 12 November 2013 +
+Copyright © 1997-2013 University of Cambridge. +
+

+Return to the PCRE index page. +

diff --git a/doc/html/pcrecompat.html b/doc/html/pcrecompat.html new file mode 100644 index 0000000..3e62266 --- /dev/null +++ b/doc/html/pcrecompat.html @@ -0,0 +1,235 @@ + + +pcrecompat specification + + +

pcrecompat man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+
+DIFFERENCES BETWEEN PCRE AND PERL +
+

+This document describes the differences in the ways that PCRE and Perl handle +regular expressions. The differences described here are with respect to Perl +versions 5.10 and above. +

+

+1. PCRE has only a subset of Perl's Unicode support. Details of what it does +have are given in the +pcreunicode +page. +

+

+2. PCRE allows repeat quantifiers only on parenthesized assertions, but they do +not mean what you might think. For example, (?!a){3} does not assert that the +next three characters are not "a". It just asserts that the next character is +not "a" three times (in principle: PCRE optimizes this to run the assertion +just once). Perl allows repeat quantifiers on other assertions such as \b, but +these do not seem to have any use. +

+

+3. Capturing subpatterns that occur inside negative lookahead assertions are +counted, but their entries in the offsets vector are never set. Perl sometimes +(but not always) sets its numerical variables from inside negative assertions. +

+

+4. Though binary zero characters are supported in the subject string, they are +not allowed in a pattern string because it is passed as a normal C string, +terminated by zero. The escape sequence \0 can be used in the pattern to +represent a binary zero. +

+

+5. The following Perl escape sequences are not supported: \l, \u, \L, +\U, and \N when followed by a character name or Unicode value. (\N on its +own, matching a non-newline character, is supported.) In fact these are +implemented by Perl's general string-handling and are not part of its pattern +matching engine. If any of these are encountered by PCRE, an error is +generated by default. However, if the PCRE_JAVASCRIPT_COMPAT option is set, +\U and \u are interpreted as JavaScript interprets them. +

+

+6. The Perl escape sequences \p, \P, and \X are supported only if PCRE is +built with Unicode character property support. The properties that can be +tested with \p and \P are limited to the general category properties such as +Lu and Nd, script names such as Greek or Han, and the derived properties Any +and L&. PCRE does support the Cs (surrogate) property, which Perl does not; the +Perl documentation says "Because Perl hides the need for the user to understand +the internal representation of Unicode characters, there is no need to +implement the somewhat messy concept of surrogates." +

+

+7. PCRE does support the \Q...\E escape for quoting substrings. Characters in +between are treated as literals. This is slightly different from Perl in that $ +and @ are also handled as literals inside the quotes. In Perl, they cause +variable interpolation (but of course PCRE does not have variables). Note the +following examples: +

+    Pattern            PCRE matches      Perl matches
+
+    \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
+    \Qabc\$xyz\E       abc\$xyz          abc\$xyz
+    \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
+
+The \Q...\E sequence is recognized both inside and outside character classes. +

+

+8. Fairly obviously, PCRE does not support the (?{code}) and (??{code}) +constructions. However, there is support for recursive patterns. This is not +available in Perl 5.8, but it is in Perl 5.10. Also, the PCRE "callout" +feature allows an external function to be called during pattern matching. See +the +pcrecallout +documentation for details. +

+

+9. Subpatterns that are called as subroutines (whether or not recursively) are +always treated as atomic groups in PCRE. This is like Python, but unlike Perl. +Captured values that are set outside a subroutine call can be reference from +inside in PCRE, but not in Perl. There is a discussion that explains these +differences in more detail in the +section on recursion differences from Perl +in the +pcrepattern +page. +

+

+10. If any of the backtracking control verbs are used in a subpattern that is +called as a subroutine (whether or not recursively), their effect is confined +to that subpattern; it does not extend to the surrounding pattern. This is not +always the case in Perl. In particular, if (*THEN) is present in a group that +is called as a subroutine, its action is limited to that group, even if the +group does not contain any | characters. Note that such subpatterns are +processed as anchored at the point where they are tested. +

+

+11. If a pattern contains more than one backtracking control verb, the first +one that is backtracked onto acts. For example, in the pattern +A(*COMMIT)B(*PRUNE)C a failure in B triggers (*COMMIT), but a failure in C +triggers (*PRUNE). Perl's behaviour is more complex; in many cases it is the +same as PCRE, but there are examples where it differs. +

+

+12. Most backtracking verbs in assertions have their normal actions. They are +not confined to the assertion. +

+

+13. There are some differences that are concerned with the settings of captured +strings when part of a pattern is repeated. For example, matching "aba" against +the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b". +

+

+14. PCRE's handling of duplicate subpattern numbers and duplicate subpattern +names is not as general as Perl's. This is a consequence of the fact the PCRE +works internally just with numbers, using an external table to translate +between numbers and names. In particular, a pattern such as (?|(?<a>A)|(?<b)B), +where the two capturing parentheses have the same number but different names, +is not supported, and causes an error at compile time. If it were allowed, it +would not be possible to distinguish which parentheses matched, because both +names map to capturing subpattern number 1. To avoid this confusing situation, +an error is given at compile time. +

+

+15. Perl recognizes comments in some places that PCRE does not, for example, +between the ( and ? at the start of a subpattern. If the /x modifier is set, +Perl allows white space between ( and ? (though current Perls warn that this is +deprecated) but PCRE never does, even if the PCRE_EXTENDED option is set. +

+

+16. Perl, when in warning mode, gives warnings for character classes such as +[A-\d] or [a-[:digit:]]. It then treats the hyphens as literals. PCRE has no +warning features, so it gives an error in these cases because they are almost +certainly user mistakes. +

+

+17. In PCRE, the upper/lower case character properties Lu and Ll are not +affected when case-independent matching is specified. For example, \p{Lu} +always matches an upper case letter. I think Perl has changed in this respect; +in the release at the time of writing (5.16), \p{Lu} and \p{Ll} match all +letters, regardless of case, when case independence is specified. +

+

+18. PCRE provides some extensions to the Perl regular expression facilities. +Perl 5.10 includes new features that are not in earlier versions of Perl, some +of which (such as named parentheses) have been in PCRE for some time. This list +is with respect to Perl 5.10: +
+
+(a) Although lookbehind assertions in PCRE must match fixed length strings, +each alternative branch of a lookbehind assertion can match a different length +of string. Perl requires them all to have the same length. +
+
+(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $ +meta-character matches only at the very end of the string. +
+
+(c) If PCRE_EXTRA is set, a backslash followed by a letter with no special +meaning is faulted. Otherwise, like Perl, the backslash is quietly ignored. +(Perl can be made to issue a warning.) +
+
+(d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is +inverted, that is, by default they are not greedy, but if followed by a +question mark they are. +
+
+(e) PCRE_ANCHORED can be used at matching time to force a pattern to be tried +only at the first matching position in the subject string. +
+
+(f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, and +PCRE_NO_AUTO_CAPTURE options for pcre_exec() have no Perl equivalents. +
+
+(g) The \R escape sequence can be restricted to match only CR, LF, or CRLF +by the PCRE_BSR_ANYCRLF option. +
+
+(h) The callout facility is PCRE-specific. +
+
+(i) The partial matching facility is PCRE-specific. +
+
+(j) Patterns compiled by PCRE can be saved and re-used at a later time, even on +different hosts that have the other endianness. However, this does not apply to +optimized data created by the just-in-time compiler. +
+
+(k) The alternative matching functions (pcre_dfa_exec(), +pcre16_dfa_exec() and pcre32_dfa_exec(),) match in a different way +and are not Perl-compatible. +
+
+(l) PCRE recognizes some special sequences such as (*CR) at the start of +a pattern that set overall options that cannot be changed within the pattern. +

+
+AUTHOR +
+

+Philip Hazel +
+University Computing Service +
+Cambridge CB2 3QH, England. +
+

+
+REVISION +
+

+Last updated: 10 November 2013 +
+Copyright © 1997-2013 University of Cambridge. +
+

+Return to the PCRE index page. +

diff --git a/doc/html/pcrecpp.html b/doc/html/pcrecpp.html new file mode 100644 index 0000000..b7eac3a --- /dev/null +++ b/doc/html/pcrecpp.html @@ -0,0 +1,368 @@ + + +pcrecpp specification + + +

pcrecpp man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+

+
SYNOPSIS OF C++ WRAPPER
+

+#include <pcrecpp.h> +

+
DESCRIPTION
+

+The C++ wrapper for PCRE was provided by Google Inc. Some additional +functionality was added by Giuseppe Maxia. This brief man page was constructed +from the notes in the pcrecpp.h file, which should be consulted for +further details. Note that the C++ wrapper supports only the original 8-bit +PCRE library. There is no 16-bit or 32-bit support at present. +

+
MATCHING INTERFACE
+

+The "FullMatch" operation checks that supplied text matches a supplied pattern +exactly. If pointer arguments are supplied, it copies matched sub-strings that +match sub-patterns into them. +

+  Example: successful match
+     pcrecpp::RE re("h.*o");
+     re.FullMatch("hello");
+
+  Example: unsuccessful match (requires full match):
+     pcrecpp::RE re("e");
+     !re.FullMatch("hello");
+
+  Example: creating a temporary RE object:
+     pcrecpp::RE("h.*o").FullMatch("hello");
+
+You can pass in a "const char*" or a "string" for "text". The examples below +tend to use a const char*. You can, as in the different examples above, store +the RE object explicitly in a variable or use a temporary RE object. The +examples below use one mode or the other arbitrarily. Either could correctly be +used for any of these examples. +

+

+You must supply extra pointer arguments to extract matched subpieces. +

+  Example: extracts "ruby" into "s" and 1234 into "i"
+     int i;
+     string s;
+     pcrecpp::RE re("(\\w+):(\\d+)");
+     re.FullMatch("ruby:1234", &s, &i);
+
+  Example: does not try to extract any extra sub-patterns
+     re.FullMatch("ruby:1234", &s);
+
+  Example: does not try to extract into NULL
+     re.FullMatch("ruby:1234", NULL, &i);
+
+  Example: integer overflow causes failure
+     !re.FullMatch("ruby:1234567891234", NULL, &i);
+
+  Example: fails because there aren't enough sub-patterns:
+     !pcrecpp::RE("\\w+:\\d+").FullMatch("ruby:1234", &s);
+
+  Example: fails because string cannot be stored in integer
+     !pcrecpp::RE("(.*)").FullMatch("ruby", &i);
+
+The provided pointer arguments can be pointers to any scalar numeric +type, or one of: +
+   string        (matched piece is copied to string)
+   StringPiece   (StringPiece is mutated to point to matched piece)
+   T             (where "bool T::ParseFrom(const char*, int)" exists)
+   NULL          (the corresponding matched sub-pattern is not copied)
+
+The function returns true iff all of the following conditions are satisfied: +
+  a. "text" matches "pattern" exactly;
+
+  b. The number of matched sub-patterns is >= number of supplied
+     pointers;
+
+  c. The "i"th argument has a suitable type for holding the
+     string captured as the "i"th sub-pattern. If you pass in
+     void * NULL for the "i"th argument, or a non-void * NULL
+     of the correct type, or pass fewer arguments than the
+     number of sub-patterns, "i"th captured sub-pattern is
+     ignored.
+
+CAVEAT: An optional sub-pattern that does not exist in the matched +string is assigned the empty string. Therefore, the following will +return false (because the empty string is not a valid number): +
+   int number;
+   pcrecpp::RE::FullMatch("abc", "[a-z]+(\\d+)?", &number);
+
+The matching interface supports at most 16 arguments per call. +If you need more, consider using the more general interface +pcrecpp::RE::DoMatch. See pcrecpp.h for the signature for +DoMatch. +

+

+NOTE: Do not use no_arg, which is used internally to mark the end of a +list of optional arguments, as a placeholder for missing arguments, as this can +lead to segfaults. +

+
QUOTING METACHARACTERS
+

+You can use the "QuoteMeta" operation to insert backslashes before all +potentially meaningful characters in a string. The returned string, used as a +regular expression, will exactly match the original string. +

+  Example:
+     string quoted = RE::QuoteMeta(unquoted);
+
+Note that it's legal to escape a character even if it has no special meaning in +a regular expression -- so this function does that. (This also makes it +identical to the perl function of the same name; see "perldoc -f quotemeta".) +For example, "1.5-2.0?" becomes "1\.5\-2\.0\?". +

+
PARTIAL MATCHES
+

+You can use the "PartialMatch" operation when you want the pattern +to match any substring of the text. +

+  Example: simple search for a string:
+     pcrecpp::RE("ell").PartialMatch("hello");
+
+  Example: find first number in a string:
+     int number;
+     pcrecpp::RE re("(\\d+)");
+     re.PartialMatch("x*100 + 20", &number);
+     assert(number == 100);
+
+

+
UTF-8 AND THE MATCHING INTERFACE
+

+By default, pattern and text are plain text, one byte per character. The UTF8 +flag, passed to the constructor, causes both pattern and string to be treated +as UTF-8 text, still a byte stream but potentially multiple bytes per +character. In practice, the text is likelier to be UTF-8 than the pattern, but +the match returned may depend on the UTF8 flag, so always use it when matching +UTF8 text. For example, "." will match one byte normally but with UTF8 set may +match up to three bytes of a multi-byte character. +

+  Example:
+     pcrecpp::RE_Options options;
+     options.set_utf8();
+     pcrecpp::RE re(utf8_pattern, options);
+     re.FullMatch(utf8_string);
+
+  Example: using the convenience function UTF8():
+     pcrecpp::RE re(utf8_pattern, pcrecpp::UTF8());
+     re.FullMatch(utf8_string);
+
+NOTE: The UTF8 flag is ignored if pcre was not configured with the +
+      --enable-utf8 flag.
+
+

+
PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE
+

+PCRE defines some modifiers to change the behavior of the regular expression +engine. The C++ wrapper defines an auxiliary class, RE_Options, as a vehicle to +pass such modifiers to a RE class. Currently, the following modifiers are +supported: +

+   modifier              description               Perl corresponding
+
+   PCRE_CASELESS         case insensitive match      /i
+   PCRE_MULTILINE        multiple lines match        /m
+   PCRE_DOTALL           dot matches newlines        /s
+   PCRE_DOLLAR_ENDONLY   $ matches only at end       N/A
+   PCRE_EXTRA            strict escape parsing       N/A
+   PCRE_EXTENDED         ignore white spaces         /x
+   PCRE_UTF8             handles UTF8 chars          built-in
+   PCRE_UNGREEDY         reverses * and *?           N/A
+   PCRE_NO_AUTO_CAPTURE  disables capturing parens   N/A (*)
+
+(*) Both Perl and PCRE allow non capturing parentheses by means of the +"?:" modifier within the pattern itself. e.g. (?:ab|cd) does not +capture, while (ab|cd) does. +

+

+For a full account on how each modifier works, please check the +PCRE API reference page. +

+

+For each modifier, there are two member functions whose name is made +out of the modifier in lowercase, without the "PCRE_" prefix. For +instance, PCRE_CASELESS is handled by +

+  bool caseless()
+
+which returns true if the modifier is set, and +
+  RE_Options & set_caseless(bool)
+
+which sets or unsets the modifier. Moreover, PCRE_EXTRA_MATCH_LIMIT can be +accessed through the set_match_limit() and match_limit() member +functions. Setting match_limit to a non-zero value will limit the +execution of pcre to keep it from doing bad things like blowing the stack or +taking an eternity to return a result. A value of 5000 is good enough to stop +stack blowup in a 2MB thread stack. Setting match_limit to zero disables +match limiting. Alternatively, you can call match_limit_recursion() +which uses PCRE_EXTRA_MATCH_LIMIT_RECURSION to limit how much PCRE +recurses. match_limit() limits the number of matches PCRE does; +match_limit_recursion() limits the depth of internal recursion, and +therefore the amount of stack that is used. +

+

+Normally, to pass one or more modifiers to a RE class, you declare +a RE_Options object, set the appropriate options, and pass this +object to a RE constructor. Example: +

+   RE_Options opt;
+   opt.set_caseless(true);
+   if (RE("HELLO", opt).PartialMatch("hello world")) ...
+
+RE_options has two constructors. The default constructor takes no arguments and +creates a set of flags that are off by default. The optional parameter +option_flags is to facilitate transfer of legacy code from C programs. +This lets you do +
+   RE(pattern,
+     RE_Options(PCRE_CASELESS|PCRE_MULTILINE)).PartialMatch(str);
+
+However, new code is better off doing +
+   RE(pattern,
+     RE_Options().set_caseless(true).set_multiline(true))
+       .PartialMatch(str);
+
+If you are going to pass one of the most used modifiers, there are some +convenience functions that return a RE_Options class with the +appropriate modifier already set: CASELESS(), UTF8(), +MULTILINE(), DOTALL(), and EXTENDED(). +

+

+If you need to set several options at once, and you don't want to go through +the pains of declaring a RE_Options object and setting several options, there +is a parallel method that give you such ability on the fly. You can concatenate +several set_xxxxx() member functions, since each of them returns a +reference to its class object. For example, to pass PCRE_CASELESS, +PCRE_EXTENDED, and PCRE_MULTILINE to a RE with one statement, you may write: +

+   RE(" ^ xyz \\s+ .* blah$",
+     RE_Options()
+       .set_caseless(true)
+       .set_extended(true)
+       .set_multiline(true)).PartialMatch(sometext);
+
+
+

+
SCANNING TEXT INCREMENTALLY
+

+The "Consume" operation may be useful if you want to repeatedly +match regular expressions at the front of a string and skip over +them as they match. This requires use of the "StringPiece" type, +which represents a sub-range of a real string. Like RE, StringPiece +is defined in the pcrecpp namespace. +

+  Example: read lines of the form "var = value" from a string.
+     string contents = ...;                 // Fill string somehow
+     pcrecpp::StringPiece input(contents);  // Wrap in a StringPiece
+
+     string var;
+     int value;
+     pcrecpp::RE re("(\\w+) = (\\d+)\n");
+     while (re.Consume(&input, &var, &value)) {
+       ...;
+     }
+
+Each successful call to "Consume" will set "var/value", and also +advance "input" so it points past the matched text. +

+

+The "FindAndConsume" operation is similar to "Consume" but does not +anchor your match at the beginning of the string. For example, you +could extract all words from a string by repeatedly calling +

+  pcrecpp::RE("(\\w+)").FindAndConsume(&input, &word)
+
+

+
PARSING HEX/OCTAL/C-RADIX NUMBERS
+

+By default, if you pass a pointer to a numeric value, the +corresponding text is interpreted as a base-10 number. You can +instead wrap the pointer with a call to one of the operators Hex(), +Octal(), or CRadix() to interpret the text in another base. The +CRadix operator interprets C-style "0" (base-8) and "0x" (base-16) +prefixes, but defaults to base-10. +

+  Example:
+    int a, b, c, d;
+    pcrecpp::RE re("(.*) (.*) (.*) (.*)");
+    re.FullMatch("100 40 0100 0x40",
+                 pcrecpp::Octal(&a), pcrecpp::Hex(&b),
+                 pcrecpp::CRadix(&c), pcrecpp::CRadix(&d));
+
+will leave 64 in a, b, c, and d. +

+
REPLACING PARTS OF STRINGS
+

+You can replace the first match of "pattern" in "str" with "rewrite". +Within "rewrite", backslash-escaped digits (\1 to \9) can be +used to insert text matching corresponding parenthesized group +from the pattern. \0 in "rewrite" refers to the entire matching +text. For example: +

+  string s = "yabba dabba doo";
+  pcrecpp::RE("b+").Replace("d", &s);
+
+will leave "s" containing "yada dabba doo". The result is true if the pattern +matches and a replacement occurs, false otherwise. +

+

+GlobalReplace is like Replace except that it replaces all +occurrences of the pattern in the string with the rewrite. Replacements are +not subject to re-matching. For example: +

+  string s = "yabba dabba doo";
+  pcrecpp::RE("b+").GlobalReplace("d", &s);
+
+will leave "s" containing "yada dada doo". It returns the number of +replacements made. +

+

+Extract is like Replace, except that if the pattern matches, +"rewrite" is copied into "out" (an additional argument) with substitutions. +The non-matching portions of "text" are ignored. Returns true iff a match +occurred and the extraction happened successfully; if no match occurs, the +string is left unaffected. +

+
AUTHOR
+

+The C++ wrapper was contributed by Google Inc. +
+Copyright © 2007 Google Inc. +
+

+
REVISION
+

+Last updated: 08 January 2012 +
+

+Return to the PCRE index page. +

diff --git a/doc/html/pcredemo.html b/doc/html/pcredemo.html new file mode 100644 index 0000000..894a930 --- /dev/null +++ b/doc/html/pcredemo.html @@ -0,0 +1,426 @@ + + +pcredemo specification + + +

pcredemo man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +
+

    +
+
+/*************************************************
+*           PCRE DEMONSTRATION PROGRAM           *
+*************************************************/
+
+/* This is a demonstration program to illustrate the most straightforward ways
+of calling the PCRE regular expression library from a C program. See the
+pcresample documentation for a short discussion ("man pcresample" if you have
+the PCRE man pages installed).
+
+In Unix-like environments, if PCRE is installed in your standard system
+libraries, you should be able to compile this program using this command:
+
+gcc -Wall pcredemo.c -lpcre -o pcredemo
+
+If PCRE is not installed in a standard place, it is likely to be installed with
+support for the pkg-config mechanism. If you have pkg-config, you can compile
+this program using this command:
+
+gcc -Wall pcredemo.c `pkg-config --cflags --libs libpcre` -o pcredemo
+
+If you do not have pkg-config, you may have to use this:
+
+gcc -Wall pcredemo.c -I/usr/local/include -L/usr/local/lib \
+  -R/usr/local/lib -lpcre -o pcredemo
+
+Replace "/usr/local/include" and "/usr/local/lib" with wherever the include and
+library files for PCRE are installed on your system. Only some operating
+systems (e.g. Solaris) use the -R option.
+
+Building under Windows:
+
+If you want to statically link this program against a non-dll .a file, you must
+define PCRE_STATIC before including pcre.h, otherwise the pcre_malloc() and
+pcre_free() exported functions will be declared __declspec(dllimport), with
+unwanted results. So in this environment, uncomment the following line. */
+
+/* #define PCRE_STATIC */
+
+#include <stdio.h>
+#include <string.h>
+#include <pcre.h>
+
+#define OVECCOUNT 30    /* should be a multiple of 3 */
+
+
+int main(int argc, char **argv)
+{
+pcre *re;
+const char *error;
+char *pattern;
+char *subject;
+unsigned char *name_table;
+unsigned int option_bits;
+int erroffset;
+int find_all;
+int crlf_is_newline;
+int namecount;
+int name_entry_size;
+int ovector[OVECCOUNT];
+int subject_length;
+int rc, i;
+int utf8;
+
+
+/**************************************************************************
+* First, sort out the command line. There is only one possible option at  *
+* the moment, "-g" to request repeated matching to find all occurrences,  *
+* like Perl's /g option. We set the variable find_all to a non-zero value *
+* if the -g option is present. Apart from that, there must be exactly two *
+* arguments.                                                              *
+**************************************************************************/
+
+find_all = 0;
+for (i = 1; i < argc; i++)
+  {
+  if (strcmp(argv[i], "-g") == 0) find_all = 1;
+    else break;
+  }
+
+/* After the options, we require exactly two arguments, which are the pattern,
+and the subject string. */
+
+if (argc - i != 2)
+  {
+  printf("Two arguments required: a regex and a subject string\n");
+  return 1;
+  }
+
+pattern = argv[i];
+subject = argv[i+1];
+subject_length = (int)strlen(subject);
+
+
+/*************************************************************************
+* Now we are going to compile the regular expression pattern, and handle *
+* and errors that are detected.                                          *
+*************************************************************************/
+
+re = pcre_compile(
+  pattern,              /* the pattern */
+  0,                    /* default options */
+  &error,               /* for error message */
+  &erroffset,           /* for error offset */
+  NULL);                /* use default character tables */
+
+/* Compilation failed: print the error message and exit */
+
+if (re == NULL)
+  {
+  printf("PCRE compilation failed at offset %d: %s\n", erroffset, error);
+  return 1;
+  }
+
+
+/*************************************************************************
+* If the compilation succeeded, we call PCRE again, in order to do a     *
+* pattern match against the subject string. This does just ONE match. If *
+* further matching is needed, it will be done below.                     *
+*************************************************************************/
+
+rc = pcre_exec(
+  re,                   /* the compiled pattern */
+  NULL,                 /* no extra data - we didn't study the pattern */
+  subject,              /* the subject string */
+  subject_length,       /* the length of the subject */
+  0,                    /* start at offset 0 in the subject */
+  0,                    /* default options */
+  ovector,              /* output vector for substring information */
+  OVECCOUNT);           /* number of elements in the output vector */
+
+/* Matching failed: handle error cases */
+
+if (rc < 0)
+  {
+  switch(rc)
+    {
+    case PCRE_ERROR_NOMATCH: printf("No match\n"); break;
+    /*
+    Handle other special cases if you like
+    */
+    default: printf("Matching error %d\n", rc); break;
+    }
+  pcre_free(re);     /* Release memory used for the compiled pattern */
+  return 1;
+  }
+
+/* Match succeded */
+
+printf("\nMatch succeeded at offset %d\n", ovector[0]);
+
+
+/*************************************************************************
+* We have found the first match within the subject string. If the output *
+* vector wasn't big enough, say so. Then output any substrings that were *
+* captured.                                                              *
+*************************************************************************/
+
+/* The output vector wasn't big enough */
+
+if (rc == 0)
+  {
+  rc = OVECCOUNT/3;
+  printf("ovector only has room for %d captured substrings\n", rc - 1);
+  }
+
+/* Show substrings stored in the output vector by number. Obviously, in a real
+application you might want to do things other than print them. */
+
+for (i = 0; i < rc; i++)
+  {
+  char *substring_start = subject + ovector[2*i];
+  int substring_length = ovector[2*i+1] - ovector[2*i];
+  printf("%2d: %.*s\n", i, substring_length, substring_start);
+  }
+
+
+/**************************************************************************
+* That concludes the basic part of this demonstration program. We have    *
+* compiled a pattern, and performed a single match. The code that follows *
+* shows first how to access named substrings, and then how to code for    *
+* repeated matches on the same subject.                                   *
+**************************************************************************/
+
+/* See if there are any named substrings, and if so, show them by name. First
+we have to extract the count of named parentheses from the pattern. */
+
+(void)pcre_fullinfo(
+  re,                   /* the compiled pattern */
+  NULL,                 /* no extra data - we didn't study the pattern */
+  PCRE_INFO_NAMECOUNT,  /* number of named substrings */
+  &namecount);          /* where to put the answer */
+
+if (namecount <= 0) printf("No named substrings\n"); else
+  {
+  unsigned char *tabptr;
+  printf("Named substrings\n");
+
+  /* Before we can access the substrings, we must extract the table for
+  translating names to numbers, and the size of each entry in the table. */
+
+  (void)pcre_fullinfo(
+    re,                       /* the compiled pattern */
+    NULL,                     /* no extra data - we didn't study the pattern */
+    PCRE_INFO_NAMETABLE,      /* address of the table */
+    &name_table);             /* where to put the answer */
+
+  (void)pcre_fullinfo(
+    re,                       /* the compiled pattern */
+    NULL,                     /* no extra data - we didn't study the pattern */
+    PCRE_INFO_NAMEENTRYSIZE,  /* size of each entry in the table */
+    &name_entry_size);        /* where to put the answer */
+
+  /* Now we can scan the table and, for each entry, print the number, the name,
+  and the substring itself. */
+
+  tabptr = name_table;
+  for (i = 0; i < namecount; i++)
+    {
+    int n = (tabptr[0] << 8) | tabptr[1];
+    printf("(%d) %*s: %.*s\n", n, name_entry_size - 3, tabptr + 2,
+      ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]);
+    tabptr += name_entry_size;
+    }
+  }
+
+
+/*************************************************************************
+* If the "-g" option was given on the command line, we want to continue  *
+* to search for additional matches in the subject string, in a similar   *
+* way to the /g option in Perl. This turns out to be trickier than you   *
+* might think because of the possibility of matching an empty string.    *
+* What happens is as follows:                                            *
+*                                                                        *
+* If the previous match was NOT for an empty string, we can just start   *
+* the next match at the end of the previous one.                         *
+*                                                                        *
+* If the previous match WAS for an empty string, we can't do that, as it *
+* would lead to an infinite loop. Instead, a special call of pcre_exec() *
+* is made with the PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED flags set.    *
+* The first of these tells PCRE that an empty string at the start of the *
+* subject is not a valid match; other possibilities must be tried. The   *
+* second flag restricts PCRE to one match attempt at the initial string  *
+* position. If this match succeeds, an alternative to the empty string   *
+* match has been found, and we can print it and proceed round the loop,  *
+* advancing by the length of whatever was found. If this match does not  *
+* succeed, we still stay in the loop, advancing by just one character.   *
+* In UTF-8 mode, which can be set by (*UTF8) in the pattern, this may be *
+* more than one byte.                                                    *
+*                                                                        *
+* However, there is a complication concerned with newlines. When the     *
+* newline convention is such that CRLF is a valid newline, we must       *
+* advance by two characters rather than one. The newline convention can  *
+* be set in the regex by (*CR), etc.; if not, we must find the default.  *
+*************************************************************************/
+
+if (!find_all)     /* Check for -g */
+  {
+  pcre_free(re);   /* Release the memory used for the compiled pattern */
+  return 0;        /* Finish unless -g was given */
+  }
+
+/* Before running the loop, check for UTF-8 and whether CRLF is a valid newline
+sequence. First, find the options with which the regex was compiled; extract
+the UTF-8 state, and mask off all but the newline options. */
+
+(void)pcre_fullinfo(re, NULL, PCRE_INFO_OPTIONS, &option_bits);
+utf8 = option_bits & PCRE_UTF8;
+option_bits &= PCRE_NEWLINE_CR|PCRE_NEWLINE_LF|PCRE_NEWLINE_CRLF|
+               PCRE_NEWLINE_ANY|PCRE_NEWLINE_ANYCRLF;
+
+/* If no newline options were set, find the default newline convention from the
+build configuration. */
+
+if (option_bits == 0)
+  {
+  int d;
+  (void)pcre_config(PCRE_CONFIG_NEWLINE, &d);
+  /* Note that these values are always the ASCII ones, even in
+  EBCDIC environments. CR = 13, NL = 10. */
+  option_bits = (d == 13)? PCRE_NEWLINE_CR :
+          (d == 10)? PCRE_NEWLINE_LF :
+          (d == (13<<8 | 10))? PCRE_NEWLINE_CRLF :
+          (d == -2)? PCRE_NEWLINE_ANYCRLF :
+          (d == -1)? PCRE_NEWLINE_ANY : 0;
+  }
+
+/* See if CRLF is a valid newline sequence. */
+
+crlf_is_newline =
+     option_bits == PCRE_NEWLINE_ANY ||
+     option_bits == PCRE_NEWLINE_CRLF ||
+     option_bits == PCRE_NEWLINE_ANYCRLF;
+
+/* Loop for second and subsequent matches */
+
+for (;;)
+  {
+  int options = 0;                 /* Normally no options */
+  int start_offset = ovector[1];   /* Start at end of previous match */
+
+  /* If the previous match was for an empty string, we are finished if we are
+  at the end of the subject. Otherwise, arrange to run another match at the
+  same point to see if a non-empty match can be found. */
+
+  if (ovector[0] == ovector[1])
+    {
+    if (ovector[0] == subject_length) break;
+    options = PCRE_NOTEMPTY_ATSTART | PCRE_ANCHORED;
+    }
+
+  /* Run the next matching operation */
+
+  rc = pcre_exec(
+    re,                   /* the compiled pattern */
+    NULL,                 /* no extra data - we didn't study the pattern */
+    subject,              /* the subject string */
+    subject_length,       /* the length of the subject */
+    start_offset,         /* starting offset in the subject */
+    options,              /* options */
+    ovector,              /* output vector for substring information */
+    OVECCOUNT);           /* number of elements in the output vector */
+
+  /* This time, a result of NOMATCH isn't an error. If the value in "options"
+  is zero, it just means we have found all possible matches, so the loop ends.
+  Otherwise, it means we have failed to find a non-empty-string match at a
+  point where there was a previous empty-string match. In this case, we do what
+  Perl does: advance the matching position by one character, and continue. We
+  do this by setting the "end of previous match" offset, because that is picked
+  up at the top of the loop as the point at which to start again.
+
+  There are two complications: (a) When CRLF is a valid newline sequence, and
+  the current position is just before it, advance by an extra byte. (b)
+  Otherwise we must ensure that we skip an entire UTF-8 character if we are in
+  UTF-8 mode. */
+
+  if (rc == PCRE_ERROR_NOMATCH)
+    {
+    if (options == 0) break;                    /* All matches found */
+    ovector[1] = start_offset + 1;              /* Advance one byte */
+    if (crlf_is_newline &&                      /* If CRLF is newline & */
+        start_offset < subject_length - 1 &&    /* we are at CRLF, */
+        subject[start_offset] == '\r' &&
+        subject[start_offset + 1] == '\n')
+      ovector[1] += 1;                          /* Advance by one more. */
+    else if (utf8)                              /* Otherwise, ensure we */
+      {                                         /* advance a whole UTF-8 */
+      while (ovector[1] < subject_length)       /* character. */
+        {
+        if ((subject[ovector[1]] & 0xc0) != 0x80) break;
+        ovector[1] += 1;
+        }
+      }
+    continue;    /* Go round the loop again */
+    }
+
+  /* Other matching errors are not recoverable. */
+
+  if (rc < 0)
+    {
+    printf("Matching error %d\n", rc);
+    pcre_free(re);    /* Release memory used for the compiled pattern */
+    return 1;
+    }
+
+  /* Match succeded */
+
+  printf("\nMatch succeeded again at offset %d\n", ovector[0]);
+
+  /* The match succeeded, but the output vector wasn't big enough. */
+
+  if (rc == 0)
+    {
+    rc = OVECCOUNT/3;
+    printf("ovector only has room for %d captured substrings\n", rc - 1);
+    }
+
+  /* As before, show substrings stored in the output vector by number, and then
+  also any named substrings. */
+
+  for (i = 0; i < rc; i++)
+    {
+    char *substring_start = subject + ovector[2*i];
+    int substring_length = ovector[2*i+1] - ovector[2*i];
+    printf("%2d: %.*s\n", i, substring_length, substring_start);
+    }
+
+  if (namecount <= 0) printf("No named substrings\n"); else
+    {
+    unsigned char *tabptr = name_table;
+    printf("Named substrings\n");
+    for (i = 0; i < namecount; i++)
+      {
+      int n = (tabptr[0] << 8) | tabptr[1];
+      printf("(%d) %*s: %.*s\n", n, name_entry_size - 3, tabptr + 2,
+        ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]);
+      tabptr += name_entry_size;
+      }
+    }
+  }      /* End of loop to find second and subsequent matches */
+
+printf("\n");
+pcre_free(re);       /* Release memory used for the compiled pattern */
+return 0;
+}
+
+/* End of pcredemo.c */
+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcregrep.html b/doc/html/pcregrep.html
new file mode 100644
index 0000000..dacbb49
--- /dev/null
+++ b/doc/html/pcregrep.html
@@ -0,0 +1,759 @@
+
+
+pcregrep specification
+
+
+
pcregrep man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+
SYNOPSIS

+

+pcregrep [options] [long options] [pattern] [path1 path2 ...]
+

+
DESCRIPTION

+

+pcregrep searches files for character patterns, in the same way as other
+grep commands do, but it uses the PCRE regular expression library to support
+patterns that are compatible with the regular expressions of Perl 5. See
+pcresyntax(3)
+for a quick-reference summary of pattern syntax, or
+pcrepattern(3)
+for a full description of the syntax and semantics of the regular expressions
+that PCRE supports.
+

+

+Patterns, whether supplied on the command line or in a separate file, are given
+without delimiters. For example:
+
+  pcregrep Thursday /etc/motd
+

+If you attempt to use delimiters (for example, by surrounding a pattern with
+slashes, as is common in Perl scripts), they are interpreted as part of the
+pattern. Quotes can of course be used to delimit patterns on the command line
+because they are interpreted by the shell, and indeed quotes are required if a
+pattern contains white space or shell metacharacters.
+

+

+The first argument that follows any option settings is treated as the single
+pattern to be matched when neither -e nor -f is present.
+Conversely, when one or both of these options are used to specify patterns, all
+arguments are treated as path names. At least one of -e, -f, or an
+argument pattern must be provided.
+

+

+If no files are specified, pcregrep reads the standard input. The
+standard input can also be referenced by a name consisting of a single hyphen.
+For example:
+
+  pcregrep some-pattern /file1 - /file3
+

+By default, each line that matches a pattern is copied to the standard
+output, and if there is more than one file, the file name is output at the
+start of each line, followed by a colon. However, there are options that can
+change how pcregrep behaves. In particular, the -M option makes it
+possible to search for patterns that span line boundaries. What defines a line
+boundary is controlled by the -N (--newline) option.
+

+

+The amount of memory used for buffering files that are being scanned is
+controlled by a parameter that can be set by the --buffer-size option.
+The default value for this parameter is specified when pcregrep is built,
+with the default default being 20K. A block of memory three times this size is
+used (to allow for buffering "before" and "after" lines). An error occurs if a
+line overflows the buffer.
+

+

+Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the greater.
+BUFSIZ is defined in <stdio.h>. When there is more than one pattern
+(specified by the use of -e and/or -f), each pattern is applied to
+each line in the order in which they are defined, except that all the -e
+patterns are tried before the -f patterns.
+

+

+By default, as soon as one pattern matches a line, no further patterns are
+considered. However, if --colour (or --color) is used to colour the
+matching substrings, or if --only-matching, --file-offsets, or
+--line-offsets is used to output only the part of the line that matched
+(either shown literally, or as an offset), scanning resumes immediately
+following the match, so that further matches on the same line can be found. If
+there are multiple patterns, they are all tried on the remainder of the line,
+but patterns that follow the one that matched are not tried on the earlier part
+of the line.
+

+

+This behaviour means that the order in which multiple patterns are specified
+can affect the output when one of the above options is used. This is no longer
+the same behaviour as GNU grep, which now manages to display earlier matches
+for later patterns (as long as there is no overlap).
+

+

+Patterns that can match an empty string are accepted, but empty string
+matches are never recognized. An example is the pattern "(super)?(man)?", in
+which all components are optional. This pattern finds all occurrences of both
+"super" and "man"; the output differs from matching with "super|man" when only
+the matching substrings are being shown.
+

+

+If the LC_ALL or LC_CTYPE environment variable is set,
+pcregrep uses the value to set a locale when calling the PCRE library.
+The --locale option can be used to override this.
+

+
SUPPORT FOR COMPRESSED FILES

+

+It is possible to compile pcregrep so that it uses libz or
+libbz2 to read files whose names end in .gz or .bz2,
+respectively. You can find out whether your binary has support for one or both
+of these file types by running it with the --help option. If the
+appropriate support is not present, files are treated as plain text. The
+standard input is always so treated.
+

+
BINARY FILES

+

+By default, a file that contains a binary zero byte within the first 1024 bytes
+is identified as a binary file, and is processed specially. (GNU grep also
+identifies binary files in this manner.) See the --binary-files option
+for a means of changing the way binary files are handled.
+

+
OPTIONS

+

+The order in which some of the options appear can affect the output. For
+example, both the -h and -l options affect the printing of file
+names. Whichever comes later in the command line will be the one that takes
+effect. Similarly, except where noted below, if an option is given twice, the
+later setting is used. Numerical values for options may be followed by K or M,
+to signify multiplication by 1024 or 1024*1024 respectively.
+

+

+--
+This terminates the list of options. It is useful if the next item on the
+command line starts with a hyphen but is not an option. This allows for the
+processing of patterns and filenames that start with hyphens.
+

+

+-A number, --after-context=number
+Output number lines of context after each matching line. If filenames
+and/or line numbers are being output, a hyphen separator is used instead of a
+colon for the context lines. A line containing "--" is output between each
+group of lines, unless they are in fact contiguous in the input file. The value
+of number is expected to be relatively small. However, pcregrep
+guarantees to have up to 8K of following text available for context output.
+

+

+-a, --text
+Treat binary files as text. This is equivalent to
+--binary-files=text.
+

+

+-B number, --before-context=number
+Output number lines of context before each matching line. If filenames
+and/or line numbers are being output, a hyphen separator is used instead of a
+colon for the context lines. A line containing "--" is output between each
+group of lines, unless they are in fact contiguous in the input file. The value
+of number is expected to be relatively small. However, pcregrep
+guarantees to have up to 8K of preceding text available for context output.
+

+

+--binary-files=word
+Specify how binary files are to be processed. If the word is "binary" (the
+default), pattern matching is performed on binary files, but the only output is
+"Binary file <name> matches" when a match succeeds. If the word is "text",
+which is equivalent to the -a or --text option, binary files are
+processed in the same way as any other file. In this case, when a match
+succeeds, the output may be binary garbage, which can have nasty effects if
+sent to a terminal. If the word is "without-match", which is equivalent to the
+-I option, binary files are not processed at all; they are assumed not to
+be of interest.
+

+

+--buffer-size=number
+Set the parameter that controls how much memory is used for buffering files
+that are being scanned.
+

+

+-C number, --context=number
+Output number lines of context both before and after each matching line.
+This is equivalent to setting both -A and -B to the same value.
+

+

+-c, --count
+Do not output individual lines from the files that are being scanned; instead
+output the number of lines that would otherwise have been shown. If no lines
+are selected, the number zero is output. If several files are are being
+scanned, a count is output for each of them. However, if the
+--files-with-matches option is also used, only those files whose counts
+are greater than zero are listed. When -c is used, the -A,
+-B, and -C options are ignored.
+

+

+--colour, --color
+If this option is given without any data, it is equivalent to "--colour=auto".
+If data is required, it must be given in the same shell item, separated by an
+equals sign.
+

+

+--colour=value, --color=value
+This option specifies under what circumstances the parts of a line that matched
+a pattern should be coloured in the output. By default, the output is not
+coloured. The value (which is optional, see above) may be "never", "always", or
+"auto". In the latter case, colouring happens only if the standard output is
+connected to a terminal. More resources are used when colouring is enabled,
+because pcregrep has to search for all possible matches in a line, not
+just one, in order to colour them all.
+

+

+The colour that is used can be specified by setting the environment variable
+PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
+string of two numbers, separated by a semicolon. They are copied directly into
+the control string for setting colour on a terminal, so it is your
+responsibility to ensure that they make sense. If neither of the environment
+variables is set, the default is "1;31", which gives red.
+

+

+-D action, --devices=action
+If an input path is not a regular file or a directory, "action" specifies how
+it is to be processed. Valid values are "read" (the default) or "skip"
+(silently skip the path).
+

+

+-d action, --directories=action
+If an input path is a directory, "action" specifies how it is to be processed.
+Valid values are "read" (the default in non-Windows environments, for
+compatibility with GNU grep), "recurse" (equivalent to the -r option), or
+"skip" (silently skip the path, the default in Windows environments). In the
+"read" case, directories are read as if they were ordinary files. In some
+operating systems the effect of reading a directory like this is an immediate
+end-of-file; in others it may provoke an error.
+

+

+-e pattern, --regex=pattern, --regexp=pattern
+Specify a pattern to be matched. This option can be used multiple times in
+order to specify several patterns. It can also be used as a way of specifying a
+single pattern that starts with a hyphen. When -e is used, no argument
+pattern is taken from the command line; all arguments are treated as file
+names. There is no limit to the number of patterns. They are applied to each
+line in the order in which they are defined until one matches.
+

+

+If -f is used with -e, the command line patterns are matched first,
+followed by the patterns from the file(s), independent of the order in which
+these options are specified. Note that multiple use of -e is not the same
+as a single pattern with alternatives. For example, X|Y finds the first
+character in a line that is X or Y, whereas if the two patterns are given
+separately, with X first, pcregrep finds X if it is present, even if it
+follows Y in the line. It finds Y only if there is no X in the line. This
+matters only if you are using -o or --colo(u)r to show the part(s)
+of the line that matched.
+

+

+--exclude=pattern
+Files (but not directories) whose names match the pattern are skipped without
+being processed. This applies to all files, whether listed on the command line,
+obtained from --file-list, or by scanning a directory. The pattern is a
+PCRE regular expression, and is matched against the final component of the file
+name, not the entire path. The -F, -w, and -x options do not
+apply to this pattern. The option may be given any number of times in order to
+specify multiple patterns. If a file name matches both an --include
+and an --exclude pattern, it is excluded. There is no short form for this
+option.
+

+

+--exclude-from=filename
+Treat each non-empty line of the file as the data for an --exclude
+option. What constitutes a newline when reading the file is the operating
+system's default. The --newline option has no effect on this option. This
+option may be given more than once in order to specify a number of files to
+read.
+

+

+--exclude-dir=pattern
+Directories whose names match the pattern are skipped without being processed,
+whatever the setting of the --recursive option. This applies to all
+directories, whether listed on the command line, obtained from
+--file-list, or by scanning a parent directory. The pattern is a PCRE
+regular expression, and is matched against the final component of the directory
+name, not the entire path. The -F, -w, and -x options do not
+apply to this pattern. The option may be given any number of times in order to
+specify more than one pattern. If a directory matches both --include-dir
+and --exclude-dir, it is excluded. There is no short form for this
+option.
+

+

+-F, --fixed-strings
+Interpret each data-matching pattern as a list of fixed strings, separated by
+newlines, instead of as a regular expression. What constitutes a newline for
+this purpose is controlled by the --newline option. The -w (match
+as a word) and -x (match whole line) options can be used with -F.
+They apply to each of the fixed strings. A line is selected if any of the fixed
+strings are found in it (subject to -w or -x, if present). This
+option applies only to the patterns that are matched against the contents of
+files; it does not apply to patterns specified by any of the --include or
+--exclude options.
+

+

+-f filename, --file=filename
+Read patterns from the file, one per line, and match them against
+each line of input. What constitutes a newline when reading the file is the
+operating system's default. The --newline option has no effect on this
+option. Trailing white space is removed from each line, and blank lines are
+ignored. An empty file contains no patterns and therefore matches nothing. See
+also the comments about multiple patterns versus a single pattern with
+alternatives in the description of -e above.
+

+

+If this option is given more than once, all the specified files are
+read. A data line is output if any of the patterns match it. A filename can
+be given as "-" to refer to the standard input. When -f is used, patterns
+specified on the command line using -e may also be present; they are
+tested before the file's patterns. However, no other pattern is taken from the
+command line; all arguments are treated as the names of paths to be searched.
+

+

+--file-list=filename
+Read a list of files and/or directories that are to be scanned from the given
+file, one per line. Trailing white space is removed from each line, and blank
+lines are ignored. These paths are processed before any that are listed on the
+command line. The filename can be given as "-" to refer to the standard input.
+If --file and --file-list are both specified as "-", patterns are
+read first. This is useful only when the standard input is a terminal, from
+which further lines (the list of files) can be read after an end-of-file
+indication. If this option is given more than once, all the specified files are
+read.
+

+

+--file-offsets
+Instead of showing lines or parts of lines that match, show each match as an
+offset from the start of the file and a length, separated by a comma. In this
+mode, no context is shown. That is, the -A, -B, and -C
+options are ignored. If there is more than one match in a line, each of them is
+shown separately. This option is mutually exclusive with --line-offsets
+and --only-matching.
+

+

+-H, --with-filename
+Force the inclusion of the filename at the start of output lines when searching
+a single file. By default, the filename is not shown in this case. For matching
+lines, the filename is followed by a colon; for context lines, a hyphen
+separator is used. If a line number is also being output, it follows the file
+name.
+

+

+-h, --no-filename
+Suppress the output filenames when searching multiple files. By default,
+filenames are shown when multiple files are searched. For matching lines, the
+filename is followed by a colon; for context lines, a hyphen separator is used.
+If a line number is also being output, it follows the file name.
+

+

+--help
+Output a help message, giving brief details of the command options and file
+type support, and then exit. Anything else on the command line is
+ignored.
+

+

+-I
+Treat binary files as never matching. This is equivalent to
+--binary-files=without-match.
+

+

+-i, --ignore-case
+Ignore upper/lower case distinctions during comparisons.
+

+

+--include=pattern
+If any --include patterns are specified, the only files that are
+processed are those that match one of the patterns (and do not match an
+--exclude pattern). This option does not affect directories, but it
+applies to all files, whether listed on the command line, obtained from
+--file-list, or by scanning a directory. The pattern is a PCRE regular
+expression, and is matched against the final component of the file name, not
+the entire path. The -F, -w, and -x options do not apply to
+this pattern. The option may be given any number of times. If a file name
+matches both an --include and an --exclude pattern, it is excluded.
+There is no short form for this option.
+

+

+--include-from=filename
+Treat each non-empty line of the file as the data for an --include
+option. What constitutes a newline for this purpose is the operating system's
+default. The --newline option has no effect on this option. This option
+may be given any number of times; all the files are read.
+

+

+--include-dir=pattern
+If any --include-dir patterns are specified, the only directories that
+are processed are those that match one of the patterns (and do not match an
+--exclude-dir pattern). This applies to all directories, whether listed
+on the command line, obtained from --file-list, or by scanning a parent
+directory. The pattern is a PCRE regular expression, and is matched against the
+final component of the directory name, not the entire path. The -F,
+-w, and -x options do not apply to this pattern. The option may be
+given any number of times. If a directory matches both --include-dir and
+--exclude-dir, it is excluded. There is no short form for this option.
+

+

+-L, --files-without-match
+Instead of outputting lines from the files, just output the names of the files
+that do not contain any lines that would have been output. Each file name is
+output once, on a separate line.
+

+

+-l, --files-with-matches
+Instead of outputting lines from the files, just output the names of the files
+containing lines that would have been output. Each file name is output
+once, on a separate line. Searching normally stops as soon as a matching line
+is found in a file. However, if the -c (count) option is also used,
+matching continues in order to obtain the correct count, and those files that
+have at least one match are listed along with their counts. Using this option
+with -c is a way of suppressing the listing of files with no matches.
+

+

+--label=name
+This option supplies a name to be used for the standard input when file names
+are being output. If not supplied, "(standard input)" is used. There is no
+short form for this option.
+

+

+--line-buffered
+When this option is given, input is read and processed line by line, and the
+output is flushed after each write. By default, input is read in large chunks,
+unless pcregrep can determine that it is reading from a terminal (which
+is currently possible only in Unix-like environments). Output to terminal is
+normally automatically flushed by the operating system. This option can be
+useful when the input or output is attached to a pipe and you do not want
+pcregrep to buffer up large amounts of data. However, its use will affect
+performance, and the -M (multiline) option ceases to work.
+

+

+--line-offsets
+Instead of showing lines or parts of lines that match, show each match as a
+line number, the offset from the start of the line, and a length. The line
+number is terminated by a colon (as usual; see the -n option), and the
+offset and length are separated by a comma. In this mode, no context is shown.
+That is, the -A, -B, and -C options are ignored. If there is
+more than one match in a line, each of them is shown separately. This option is
+mutually exclusive with --file-offsets and --only-matching.
+

+

+--locale=locale-name
+This option specifies a locale to be used for pattern matching. It overrides
+the value in the LC_ALL or LC_CTYPE environment variables. If no
+locale is specified, the PCRE library's default (usually the "C" locale) is
+used. There is no short form for this option.
+

+

+--match-limit=number
+Processing some regular expression patterns can require a very large amount of
+memory, leading in some cases to a program crash if not enough is available.
+Other patterns may take a very long time to search for all possible matching
+strings. The pcre_exec() function that is called by pcregrep to do
+the matching has two parameters that can limit the resources that it uses.
+

+

+The --match-limit option provides a means of limiting resource usage
+when processing patterns that are not going to match, but which have a very
+large number of possibilities in their search trees. The classic example is a
+pattern that uses nested unlimited repeats. Internally, PCRE uses a function
+called match() which it calls repeatedly (sometimes recursively). The
+limit set by --match-limit is imposed on the number of times this
+function is called during a match, which has the effect of limiting the amount
+of backtracking that can take place.
+

+

+The --recursion-limit option is similar to --match-limit, but
+instead of limiting the total number of times that match() is called, it
+limits the depth of recursive calls, which in turn limits the amount of memory
+that can be used. The recursion depth is a smaller number than the total number
+of calls, because not all calls to match() are recursive. This limit is
+of use only if it is set smaller than --match-limit.
+

+

+There are no short forms for these options. The default settings are specified
+when the PCRE library is compiled, with the default default being 10 million.
+

+

+-M, --multiline
+Allow patterns to match more than one line. When this option is given, patterns
+may usefully contain literal newline characters and internal occurrences of ^
+and $ characters. The output for a successful match may consist of more than
+one line, the last of which is the one in which the match ended. If the matched
+string ends with a newline sequence the output ends at the end of that line.
+

+

+When this option is set, the PCRE library is called in "multiline" mode.
+There is a limit to the number of lines that can be matched, imposed by the way
+that pcregrep buffers the input file as it scans it. However,
+pcregrep ensures that at least 8K characters or the rest of the document
+(whichever is the shorter) are available for forward matching, and similarly
+the previous 8K characters (or all the previous characters, if fewer than 8K)
+are guaranteed to be available for lookbehind assertions. This option does not
+work when input is read line by line (see \fP--line-buffered\fP.)
+

+

+-N newline-type, --newline=newline-type
+The PCRE library supports five different conventions for indicating
+the ends of lines. They are the single-character sequences CR (carriage return)
+and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
+which recognizes any of the preceding three types, and an "any" convention, in
+which any Unicode line ending sequence is assumed to end a line. The Unicode
+sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
+(form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
+PS (paragraph separator, U+2029).
+

+

+When the PCRE library is built, a default line-ending sequence is specified.
+This is normally the standard sequence for the operating system. Unless
+otherwise specified by this option, pcregrep uses the library's default.
+The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
+makes it possible to use pcregrep to scan files that have come from other
+environments without having to modify their line endings. If the data that is
+being scanned does not agree with the convention set by this option,
+pcregrep may behave in strange ways. Note that this option does not
+apply to files specified by the -f, --exclude-from, or
+--include-from options, which are expected to use the operating system's
+standard newline sequence.
+

+

+-n, --line-number
+Precede each output line by its line number in the file, followed by a colon
+for matching lines or a hyphen for context lines. If the filename is also being
+output, it precedes the line number. This option is forced if
+--line-offsets is used.
+

+

+--no-jit
+If the PCRE library is built with support for just-in-time compiling (which
+speeds up matching), pcregrep automatically makes use of this, unless it
+was explicitly disabled at build time. This option can be used to disable the
+use of JIT at run time. It is provided for testing and working round problems.
+It should never be needed in normal use.
+

+

+-o, --only-matching
+Show only the part of the line that matched a pattern instead of the whole
+line. In this mode, no context is shown. That is, the -A, -B, and
+-C options are ignored. If there is more than one match in a line, each
+of them is shown separately. If -o is combined with -v (invert the
+sense of the match to find non-matching lines), no output is generated, but the
+return code is set appropriately. If the matched portion of the line is empty,
+nothing is output unless the file name or line number are being printed, in
+which case they are shown on an otherwise empty line. This option is mutually
+exclusive with --file-offsets and --line-offsets.
+

+

+-onumber, --only-matching=number
+Show only the part of the line that matched the capturing parentheses of the
+given number. Up to 32 capturing parentheses are supported, and -o0 is
+equivalent to -o without a number. Because these options can be given
+without an argument (see above), if an argument is present, it must be given in
+the same shell item, for example, -o3 or --only-matching=2. The comments given
+for the non-argument case above also apply to this case. If the specified
+capturing parentheses do not exist in the pattern, or were not set in the
+match, nothing is output unless the file name or line number are being printed.
+

+

+If this option is given multiple times, multiple substrings are output, in the
+order the options are given. For example, -o3 -o1 -o3 causes the substrings
+matched by capturing parentheses 3 and 1 and then 3 again to be output. By
+default, there is no separator (but see the next option).
+

+

+--om-separator=text
+Specify a separating string for multiple occurrences of -o. The default
+is an empty string. Separating strings are never coloured.
+

+

+-q, --quiet
+Work quietly, that is, display nothing except error messages. The exit
+status indicates whether or not any matches were found.
+

+

+-r, --recursive
+If any given path is a directory, recursively scan the files it contains,
+taking note of any --include and --exclude settings. By default, a
+directory is read as a normal file; in some operating systems this gives an
+immediate end-of-file. This option is a shorthand for setting the -d
+option to "recurse".
+

+

+--recursion-limit=number
+See --match-limit above.
+

+

+-s, --no-messages
+Suppress error messages about non-existent or unreadable files. Such files are
+quietly skipped. However, the return code is still 2, even if matches were
+found in other files.
+

+

+-u, --utf-8
+Operate in UTF-8 mode. This option is available only if PCRE has been compiled
+with UTF-8 support. All patterns (including those for any --exclude and
+--include options) and all subject lines that are scanned must be valid
+strings of UTF-8 characters.
+

+

+-V, --version
+Write the version numbers of pcregrep and the PCRE library to the
+standard output and then exit. Anything else on the command line is
+ignored.
+

+

+-v, --invert-match
+Invert the sense of the match, so that lines which do not match any of
+the patterns are the ones that are found.
+

+

+-w, --word-regex, --word-regexp
+Force the patterns to match only whole words. This is equivalent to having \b
+at the start and end of the pattern. This option applies only to the patterns
+that are matched against the contents of files; it does not apply to patterns
+specified by any of the --include or --exclude options.
+

+

+-x, --line-regex, --line-regexp
+Force the patterns to be anchored (each must start matching at the beginning of
+a line) and in addition, require them to match entire lines. This is equivalent
+to having ^ and $ characters at the start and end of each alternative branch in
+every pattern. This option applies only to the patterns that are matched
+against the contents of files; it does not apply to patterns specified by any
+of the --include or --exclude options.
+

+
ENVIRONMENT VARIABLES

+

+The environment variables LC_ALL and LC_CTYPE are examined, in that
+order, for a locale. The first one that is set is used. This can be overridden
+by the --locale option. If no locale is set, the PCRE library's default
+(usually the "C" locale) is used.
+

+
NEWLINES

+

+The -N (--newline) option allows pcregrep to scan files with
+different newline conventions from the default. Any parts of the input files
+that are written to the standard output are copied identically, with whatever
+newline sequences they have in the input. However, the setting of this option
+does not affect the interpretation of files specified by the -f,
+--exclude-from, or --include-from options, which are assumed to use
+the operating system's standard newline sequence, nor does it affect the way in
+which pcregrep writes informational messages to the standard error and
+output streams. For these it uses the string "\n" to indicate newlines,
+relying on the C I/O library to convert this to an appropriate sequence.
+

+
OPTIONS COMPATIBILITY

+

+Many of the short and long forms of pcregrep's options are the same
+as in the GNU grep program. Any long option of the form
+--xxx-regexp (GNU terminology) is also available as --xxx-regex
+(PCRE terminology). However, the --file-list, --file-offsets,
+--include-dir, --line-offsets, --locale, --match-limit,
+-M, --multiline, -N, --newline, --om-separator,
+--recursion-limit, -u, and --utf-8 options are specific to
+pcregrep, as is the use of the --only-matching option with a
+capturing parentheses number.
+

+

+Although most of the common options work the same way, a few are different in
+pcregrep. For example, the --include option's argument is a glob
+for GNU grep, but a regular expression for pcregrep. If both the
+-c and -l options are given, GNU grep lists only file names,
+without counts, but pcregrep gives the counts.
+

+
OPTIONS WITH DATA

+

+There are four different ways in which an option with data can be specified.
+If a short form option is used, the data may follow immediately, or (with one
+exception) in the next command line item. For example:
+
+  -f/some/file
+  -f /some/file
+

+The exception is the -o option, which may appear with or without data.
+Because of this, if data is present, it must follow immediately in the same
+item, for example -o3.
+

+

+If a long form option is used, the data may appear in the same command line
+item, separated by an equals character, or (with two exceptions) it may appear
+in the next command line item. For example:
+
+  --file=/some/file
+  --file /some/file
+

+Note, however, that if you want to supply a file name beginning with ~ as data
+in a shell command, and have the shell expand ~ to a home directory, you must
+separate the file name from the option, because the shell does not treat ~
+specially unless it is at the start of an item.
+

+

+The exceptions to the above are the --colour (or --color) and
+--only-matching options, for which the data is optional. If one of these
+options does have data, it must be given in the first form, using an equals
+character. Otherwise pcregrep will assume that it has no data.
+

+
MATCHING ERRORS

+

+It is possible to supply a regular expression that takes a very long time to
+fail to match certain lines. Such patterns normally involve nested indefinite
+repeats, for example: (a+)*\d when matched against a line of a's with no final
+digit. The PCRE matching function has a resource limit that causes it to abort
+in these circumstances. If this happens, pcregrep outputs an error
+message and the line that caused the problem to the standard error stream. If
+there are more than 20 such errors, pcregrep gives up.
+

+

+The --match-limit option of pcregrep can be used to set the overall
+resource limit; there is a second option called --recursion-limit that
+sets a limit on the amount of memory (usually stack) that is used (see the
+discussion of these options above).
+

+
DIAGNOSTICS

+

+Exit status is 0 if any matches were found, 1 if no matches were found, and 2
+for syntax errors, overlong lines, non-existent or inaccessible files (even if
+matches were found in other files) or too many matching errors. Using the
+-s option to suppress error messages about inaccessible files does not
+affect the return code.
+

+
SEE ALSO

+

+pcrepattern(3), pcresyntax(3), pcretest(1).
+

+
AUTHOR

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+
REVISION

+

+Last updated: 03 April 2014
+

+Copyright © 1997-2014 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcrejit.html b/doc/html/pcrejit.html
new file mode 100644
index 0000000..210f1da
--- /dev/null
+++ b/doc/html/pcrejit.html
@@ -0,0 +1,452 @@
+
+
+pcrejit specification
+
+
+
pcrejit man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+
PCRE JUST-IN-TIME COMPILER SUPPORT

+

+Just-in-time compiling is a heavyweight optimization that can greatly speed up
+pattern matching. However, it comes at the cost of extra processing before the
+match is performed. Therefore, it is of most benefit when the same pattern is
+going to be matched many times. This does not necessarily mean many calls of a
+matching function; if the pattern is not anchored, matching attempts may take
+place many times at various positions in the subject, even for a single call.
+Therefore, if the subject string is very long, it may still pay to use JIT for
+one-off matches.
+

+

+JIT support applies only to the traditional Perl-compatible matching function.
+It does not apply when the DFA matching function is being used. The code for
+this support was written by Zoltan Herczeg.
+

+
8-BIT, 16-BIT AND 32-BIT SUPPORT

+

+JIT support is available for all of the 8-bit, 16-bit and 32-bit PCRE
+libraries. To keep this documentation simple, only the 8-bit interface is
+described in what follows. If you are using the 16-bit library, substitute the
+16-bit functions and 16-bit structures (for example, pcre16_jit_stack
+instead of pcre_jit_stack). If you are using the 32-bit library,
+substitute the 32-bit functions and 32-bit structures (for example,
+pcre32_jit_stack instead of pcre_jit_stack).
+

+
AVAILABILITY OF JIT SUPPORT

+

+JIT support is an optional feature of PCRE. The "configure" option --enable-jit
+(or equivalent CMake option) must be set when PCRE is built if you want to use
+JIT. The support is limited to the following hardware platforms:
+
+  ARM v5, v7, and Thumb2
+  Intel x86 32-bit and 64-bit
+  MIPS 32-bit
+  Power PC 32-bit and 64-bit
+  SPARC 32-bit (experimental)
+

+If --enable-jit is set on an unsupported platform, compilation fails.
+

+

+A program that is linked with PCRE 8.20 or later can tell if JIT support is
+available by calling pcre_config() with the PCRE_CONFIG_JIT option. The
+result is 1 when JIT is available, and 0 otherwise. However, a simple program
+does not need to check this in order to use JIT. The normal API is implemented
+in a way that falls back to the interpretive code if JIT is not available. For
+programs that need the best possible performance, there is also a "fast path"
+API that is JIT-specific.
+

+

+If your program may sometimes be linked with versions of PCRE that are older
+than 8.20, but you want to use JIT when it is available, you can test
+the values of PCRE_MAJOR and PCRE_MINOR, or the existence of a JIT macro such
+as PCRE_CONFIG_JIT, for compile-time control of your code.
+

+
SIMPLE USE OF JIT

+

+You have to do two things to make use of the JIT support in the simplest way:
+
+  (1) Call pcre_study() with the PCRE_STUDY_JIT_COMPILE option for
+      each compiled pattern, and pass the resulting pcre_extra block to
+      pcre_exec().
+
+  (2) Use pcre_free_study() to free the pcre_extra block when it is
+      no longer needed, instead of just freeing it yourself. This ensures that
+      any JIT data is also freed.
+

+For a program that may be linked with pre-8.20 versions of PCRE, you can insert
+
+  #ifndef PCRE_STUDY_JIT_COMPILE
+  #define PCRE_STUDY_JIT_COMPILE 0
+  #endif
+

+so that no option is passed to pcre_study(), and then use something like
+this to free the study data:
+
+  #ifdef PCRE_CONFIG_JIT
+      pcre_free_study(study_ptr);
+  #else
+      pcre_free(study_ptr);
+  #endif
+

+PCRE_STUDY_JIT_COMPILE requests the JIT compiler to generate code for complete
+matches. If you want to run partial matches using the PCRE_PARTIAL_HARD or
+PCRE_PARTIAL_SOFT options of pcre_exec(), you should set one or both of
+the following options in addition to, or instead of, PCRE_STUDY_JIT_COMPILE
+when you call pcre_study():
+
+  PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+  PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+

+The JIT compiler generates different optimized code for each of the three
+modes (normal, soft partial, hard partial). When pcre_exec() is called,
+the appropriate code is run if it is available. Otherwise, the pattern is
+matched using interpretive code.
+

+

+In some circumstances you may need to call additional functions. These are
+described in the section entitled
+"Controlling the JIT stack"
+below.
+

+

+If JIT support is not available, PCRE_STUDY_JIT_COMPILE etc. are ignored, and
+no JIT data is created. Otherwise, the compiled pattern is passed to the JIT
+compiler, which turns it into machine code that executes much faster than the
+normal interpretive code. When pcre_exec() is passed a pcre_extra
+block containing a pointer to JIT code of the appropriate mode (normal or
+hard/soft partial), it obeys that code instead of running the interpreter. The
+result is identical, but the compiled JIT code runs much faster.
+

+

+There are some pcre_exec() options that are not supported for JIT
+execution. There are also some pattern items that JIT cannot handle. Details
+are given below. In both cases, execution automatically falls back to the
+interpretive code. If you want to know whether JIT was actually used for a
+particular match, you should arrange for a JIT callback function to be set up
+as described in the section entitled
+"Controlling the JIT stack"
+below, even if you do not need to supply a non-default JIT stack. Such a
+callback function is called whenever JIT code is about to be obeyed. If the
+execution options are not right for JIT execution, the callback function is not
+obeyed.
+

+

+If the JIT compiler finds an unsupported item, no JIT data is generated. You
+can find out if JIT execution is available after studying a pattern by calling
+pcre_fullinfo() with the PCRE_INFO_JIT option. A result of 1 means that
+JIT compilation was successful. A result of 0 means that JIT support is not
+available, or the pattern was not studied with PCRE_STUDY_JIT_COMPILE etc., or
+the JIT compiler was not able to handle the pattern.
+

+

+Once a pattern has been studied, with or without JIT, it can be used as many
+times as you like for matching different subject strings.
+

+
UNSUPPORTED OPTIONS AND PATTERN ITEMS

+

+The only pcre_exec() options that are supported for JIT execution are
+PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK, PCRE_NO_UTF32_CHECK, PCRE_NOTBOL,
+PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and
+PCRE_PARTIAL_SOFT.
+

+

+The only unsupported pattern items are \C (match a single data unit) when
+running in a UTF mode, and a callout immediately before an assertion condition
+in a conditional group.
+

+
RETURN VALUES FROM JIT EXECUTION

+

+When a pattern is matched using JIT execution, the return values are the same
+as those given by the interpretive pcre_exec() code, with the addition of
+one new error code: PCRE_ERROR_JIT_STACKLIMIT. This means that the memory used
+for the JIT stack was insufficient. See
+"Controlling the JIT stack"
+below for a discussion of JIT stack usage. For compatibility with the
+interpretive pcre_exec() code, no more than two-thirds of the
+ovector argument is used for passing back captured substrings.
+

+

+The error code PCRE_ERROR_MATCHLIMIT is returned by the JIT code if searching a
+very large pattern tree goes on for too long, as it is in the same circumstance
+when JIT is not used, but the details of exactly what is counted are not the
+same. The PCRE_ERROR_RECURSIONLIMIT error code is never returned by JIT
+execution.
+

+
SAVING AND RESTORING COMPILED PATTERNS

+

+The code that is generated by the JIT compiler is architecture-specific, and is
+also position dependent. For those reasons it cannot be saved (in a file or
+database) and restored later like the bytecode and other data of a compiled
+pattern. Saving and restoring compiled patterns is not something many people
+do. More detail about this facility is given in the
+pcreprecompile
+documentation. It should be possible to run pcre_study() on a saved and
+restored pattern, and thereby recreate the JIT data, but because JIT
+compilation uses significant resources, it is probably not worth doing this;
+you might as well recompile the original pattern.
+

+
CONTROLLING THE JIT STACK

+

+When the compiled JIT code runs, it needs a block of memory to use as a stack.
+By default, it uses 32K on the machine stack. However, some large or
+complicated patterns need more than this. The error PCRE_ERROR_JIT_STACKLIMIT
+is given when there is not enough stack. Three functions are provided for
+managing blocks of memory for use as JIT stacks. There is further discussion
+about the use of JIT stacks in the section entitled
+"JIT stack FAQ"
+below.
+

+

+The pcre_jit_stack_alloc() function creates a JIT stack. Its arguments
+are a starting size and a maximum size, and it returns a pointer to an opaque
+structure of type pcre_jit_stack, or NULL if there is an error. The
+pcre_jit_stack_free() function can be used to free a stack that is no
+longer needed. (For the technically minded: the address space is allocated by
+mmap or VirtualAlloc.)
+

+

+JIT uses far less memory for recursion than the interpretive code,
+and a maximum stack size of 512K to 1M should be more than enough for any
+pattern.
+

+

+The pcre_assign_jit_stack() function specifies which stack JIT code
+should use. Its arguments are as follows:
+
+  pcre_extra         *extra
+  pcre_jit_callback  callback
+  void               *data
+

+The extra argument must be the result of studying a pattern with
+PCRE_STUDY_JIT_COMPILE etc. There are three cases for the values of the other
+two options:
+
+  (1) If callback is NULL and data is NULL, an internal 32K block
+      on the machine stack is used.
+
+  (2) If callback is NULL and data is not NULL, data must be
+      a valid JIT stack, the result of calling pcre_jit_stack_alloc().
+
+  (3) If callback is not NULL, it must point to a function that is
+      called with data as an argument at the start of matching, in
+      order to set up a JIT stack. If the return from the callback
+      function is NULL, the internal 32K stack is used; otherwise the
+      return value must be a valid JIT stack, the result of calling
+      pcre_jit_stack_alloc().
+

+A callback function is obeyed whenever JIT code is about to be run; it is not
+obeyed when pcre_exec() is called with options that are incompatible for
+JIT execution. A callback function can therefore be used to determine whether a
+match operation was executed by JIT or by the interpreter.
+

+

+You may safely use the same JIT stack for more than one pattern (either by
+assigning directly or by callback), as long as the patterns are all matched
+sequentially in the same thread. In a multithread application, if you do not
+specify a JIT stack, or if you assign or pass back NULL from a callback, that
+is thread-safe, because each thread has its own machine stack. However, if you
+assign or pass back a non-NULL JIT stack, this must be a different stack for
+each thread so that the application is thread-safe.
+

+

+Strictly speaking, even more is allowed. You can assign the same non-NULL stack
+to any number of patterns as long as they are not used for matching by multiple
+threads at the same time. For example, you can assign the same stack to all
+compiled patterns, and use a global mutex in the callback to wait until the
+stack is available for use. However, this is an inefficient solution, and not
+recommended.
+

+

+This is a suggestion for how a multithreaded program that needs to set up
+non-default JIT stacks might operate:
+
+  During thread initalization
+    thread_local_var = pcre_jit_stack_alloc(...)
+
+  During thread exit
+    pcre_jit_stack_free(thread_local_var)
+
+  Use a one-line callback function
+    return thread_local_var
+

+All the functions described in this section do nothing if JIT is not available,
+and pcre_assign_jit_stack() does nothing unless the extra argument
+is non-NULL and points to a pcre_extra block that is the result of a
+successful study with PCRE_STUDY_JIT_COMPILE etc.
+

+
JIT STACK FAQ

+

+(1) Why do we need JIT stacks?
+

+

+PCRE (and JIT) is a recursive, depth-first engine, so it needs a stack where
+the local data of the current node is pushed before checking its child nodes.
+Allocating real machine stack on some platforms is difficult. For example, the
+stack chain needs to be updated every time if we extend the stack on PowerPC.
+Although it is possible, its updating time overhead decreases performance. So
+we do the recursion in memory.
+

+

+(2) Why don't we simply allocate blocks of memory with malloc()?
+

+

+Modern operating systems have a nice feature: they can reserve an address space
+instead of allocating memory. We can safely allocate memory pages inside this
+address space, so the stack could grow without moving memory data (this is
+important because of pointers). Thus we can allocate 1M address space, and use
+only a single memory page (usually 4K) if that is enough. However, we can still
+grow up to 1M anytime if needed.
+

+

+(3) Who "owns" a JIT stack?
+

+

+The owner of the stack is the user program, not the JIT studied pattern or
+anything else. The user program must ensure that if a stack is used by
+pcre_exec(), (that is, it is assigned to the pattern currently running),
+that stack must not be used by any other threads (to avoid overwriting the same
+memory area). The best practice for multithreaded programs is to allocate a
+stack for each thread, and return this stack through the JIT callback function.
+

+

+(4) When should a JIT stack be freed?
+

+

+You can free a JIT stack at any time, as long as it will not be used by
+pcre_exec() again. When you assign the stack to a pattern, only a pointer
+is set. There is no reference counting or any other magic. You can free the
+patterns and stacks in any order, anytime. Just do not call
+pcre_exec() with a pattern pointing to an already freed stack, as that
+will cause SEGFAULT. (Also, do not free a stack currently used by
+pcre_exec() in another thread). You can also replace the stack for a
+pattern at any time. You can even free the previous stack before assigning a
+replacement.
+

+

+(5) Should I allocate/free a stack every time before/after calling
+pcre_exec()?
+

+

+No, because this is too costly in terms of resources. However, you could
+implement some clever idea which release the stack if it is not used in let's
+say two minutes. The JIT callback can help to achieve this without keeping a
+list of the currently JIT studied patterns.
+

+

+(6) OK, the stack is for long term memory allocation. But what happens if a
+pattern causes stack overflow with a stack of 1M? Is that 1M kept until the
+stack is freed?
+

+

+Especially on embedded sytems, it might be a good idea to release memory
+sometimes without freeing the stack. There is no API for this at the moment.
+Probably a function call which returns with the currently allocated memory for
+any stack and another which allows releasing memory (shrinking the stack) would
+be a good idea if someone needs this.
+

+

+(7) This is too much of a headache. Isn't there any better solution for JIT
+stack handling?
+

+

+No, thanks to Windows. If POSIX threads were used everywhere, we could throw
+out this complicated API.
+

+
EXAMPLE CODE

+

+This is a single-threaded example that specifies a JIT stack without using a
+callback.
+
+  int rc;
+  int ovector[30];
+  pcre *re;
+  pcre_extra *extra;
+  pcre_jit_stack *jit_stack;
+
+  re = pcre_compile(pattern, 0, &error, &erroffset, NULL);
+  /* Check for errors */
+  extra = pcre_study(re, PCRE_STUDY_JIT_COMPILE, &error);
+  jit_stack = pcre_jit_stack_alloc(32*1024, 512*1024);
+  /* Check for error (NULL) */
+  pcre_assign_jit_stack(extra, NULL, jit_stack);
+  rc = pcre_exec(re, extra, subject, length, 0, 0, ovector, 30);
+  /* Check results */
+  pcre_free(re);
+  pcre_free_study(extra);
+  pcre_jit_stack_free(jit_stack);
+
+

+

+
JIT FAST PATH API

+

+Because the API described above falls back to interpreted execution when JIT is
+not available, it is convenient for programs that are written for general use
+in many environments. However, calling JIT via pcre_exec() does have a
+performance impact. Programs that are written for use where JIT is known to be
+available, and which need the best possible performance, can instead use a
+"fast path" API to call JIT execution directly instead of calling
+pcre_exec() (obviously only for patterns that have been successfully
+studied by JIT).
+

+

+The fast path function is called pcre_jit_exec(), and it takes exactly
+the same arguments as pcre_exec(), plus one additional argument that
+must point to a JIT stack. The JIT stack arrangements described above do not
+apply. The return values are the same as for pcre_exec().
+

+

+When you call pcre_exec(), as well as testing for invalid options, a
+number of other sanity checks are performed on the arguments. For example, if
+the subject pointer is NULL, or its length is negative, an immediate error is
+given. Also, unless PCRE_NO_UTF[8|16|32] is set, a UTF subject string is tested
+for validity. In the interests of speed, these checks do not happen on the JIT
+fast path, and if invalid data is passed, the result is undefined.
+

+

+Bypassing the sanity checks and the pcre_exec() wrapping can give
+speedups of more than 10%.
+

+
SEE ALSO

+

+pcreapi(3)
+

+
AUTHOR

+

+Philip Hazel (FAQ by Zoltan Herczeg)
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+
REVISION

+

+Last updated: 17 March 2013
+

+Copyright © 1997-2013 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcrelimits.html b/doc/html/pcrelimits.html
new file mode 100644
index 0000000..ee5ebf0
--- /dev/null
+++ b/doc/html/pcrelimits.html
@@ -0,0 +1,90 @@
+
+
+pcrelimits specification
+
+
+
pcrelimits man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+SIZE AND OTHER LIMITATIONS
+

+

+There are some size limitations in PCRE but it is hoped that they will never in
+practice be relevant.
+

+

+The maximum length of a compiled pattern is approximately 64K data units (bytes
+for the 8-bit library, 16-bit units for the 16-bit library, and 32-bit units for
+the 32-bit library) if PCRE is compiled with the default internal linkage size,
+which is 2 bytes for the 8-bit and 16-bit libraries, and 4 bytes for the 32-bit
+library. If you want to process regular expressions that are truly enormous,
+you can compile PCRE with an internal linkage size of 3 or 4 (when building the
+16-bit or 32-bit library, 3 is rounded up to 4). See the README file in
+the source distribution and the
+pcrebuild
+documentation for details. In these cases the limit is substantially larger.
+However, the speed of execution is slower.
+

+

+All values in repeating quantifiers must be less than 65536.
+

+

+There is no limit to the number of parenthesized subpatterns, but there can be
+no more than 65535 capturing subpatterns. There is, however, a limit to the
+depth of nesting of parenthesized subpatterns of all kinds. This is imposed in
+order to limit the amount of system stack used at compile time. The limit can
+be specified when PCRE is built; the default is 250.
+

+

+There is a limit to the number of forward references to subsequent subpatterns
+of around 200,000. Repeated forward references with fixed upper limits, for
+example, (?2){0,100} when subpattern number 2 is to the right, are included in
+the count. There is no limit to the number of backward references.
+

+

+The maximum length of name for a named subpattern is 32 characters, and the
+maximum number of named subpatterns is 10000.
+

+

+The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb
+is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit libraries.
+

+

+The maximum length of a subject string is the largest positive number that an
+integer variable can hold. However, when using the traditional matching
+function, PCRE uses recursion to handle subpatterns and indefinite repetition.
+This means that the available stack space may limit the size of a subject
+string that can be processed by certain patterns. For a discussion of stack
+issues, see the
+pcrestack
+documentation.
+

+

+AUTHOR
+

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+

+REVISION
+

+

+Last updated: 05 November 2013
+

+Copyright © 1997-2013 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcrematching.html b/doc/html/pcrematching.html
new file mode 100644
index 0000000..a1af39b
--- /dev/null
+++ b/doc/html/pcrematching.html
@@ -0,0 +1,242 @@
+
+
+pcrematching specification
+
+
+
pcrematching man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+
PCRE MATCHING ALGORITHMS

+

+This document describes the two different algorithms that are available in PCRE
+for matching a compiled regular expression against a given subject string. The
+"standard" algorithm is the one provided by the pcre_exec(),
+pcre16_exec() and pcre32_exec() functions. These work in the same
+as as Perl's matching function, and provide a Perl-compatible matching operation.
+The just-in-time (JIT) optimization that is described in the
+pcrejit
+documentation is compatible with these functions.
+

+

+An alternative algorithm is provided by the pcre_dfa_exec(),
+pcre16_dfa_exec() and pcre32_dfa_exec() functions; they operate in
+a different way, and are not Perl-compatible. This alternative has advantages
+and disadvantages compared with the standard algorithm, and these are described
+below.
+

+

+When there is only one possible way in which a given subject string can match a
+pattern, the two algorithms give the same answer. A difference arises, however,
+when there are multiple possibilities. For example, if the pattern
+
+  ^<.*>
+

+is matched against the string
+
+  <something> <something else> <something further>
+

+there are three possible answers. The standard algorithm finds only one of
+them, whereas the alternative algorithm finds all three.
+

+
REGULAR EXPRESSIONS AS TREES

+

+The set of strings that are matched by a regular expression can be represented
+as a tree structure. An unlimited repetition in the pattern makes the tree of
+infinite size, but it is still a tree. Matching the pattern to a given subject
+string (from a given starting point) can be thought of as a search of the tree.
+There are two ways to search a tree: depth-first and breadth-first, and these
+correspond to the two matching algorithms provided by PCRE.
+

+
THE STANDARD MATCHING ALGORITHM

+

+In the terminology of Jeffrey Friedl's book "Mastering Regular
+Expressions", the standard algorithm is an "NFA algorithm". It conducts a
+depth-first search of the pattern tree. That is, it proceeds along a single
+path through the tree, checking that the subject matches what is required. When
+there is a mismatch, the algorithm tries any alternatives at the current point,
+and if they all fail, it backs up to the previous branch point in the tree, and
+tries the next alternative branch at that level. This often involves backing up
+(moving to the left) in the subject string as well. The order in which
+repetition branches are tried is controlled by the greedy or ungreedy nature of
+the quantifier.
+

+

+If a leaf node is reached, a matching string has been found, and at that point
+the algorithm stops. Thus, if there is more than one possible match, this
+algorithm returns the first one that it finds. Whether this is the shortest,
+the longest, or some intermediate length depends on the way the greedy and
+ungreedy repetition quantifiers are specified in the pattern.
+

+

+Because it ends up with a single path through the tree, it is relatively
+straightforward for this algorithm to keep track of the substrings that are
+matched by portions of the pattern in parentheses. This provides support for
+capturing parentheses and back references.
+

+
THE ALTERNATIVE MATCHING ALGORITHM

+

+This algorithm conducts a breadth-first search of the tree. Starting from the
+first matching point in the subject, it scans the subject string from left to
+right, once, character by character, and as it does this, it remembers all the
+paths through the tree that represent valid matches. In Friedl's terminology,
+this is a kind of "DFA algorithm", though it is not implemented as a
+traditional finite state machine (it keeps multiple states active
+simultaneously).
+

+

+Although the general principle of this matching algorithm is that it scans the
+subject string only once, without backtracking, there is one exception: when a
+lookaround assertion is encountered, the characters following or preceding the
+current point have to be independently inspected.
+

+

+The scan continues until either the end of the subject is reached, or there are
+no more unterminated paths. At this point, terminated paths represent the
+different matching possibilities (if there are none, the match has failed).
+Thus, if there is more than one possible match, this algorithm finds all of
+them, and in particular, it finds the longest. The matches are returned in
+decreasing order of length. There is an option to stop the algorithm after the
+first match (which is necessarily the shortest) is found.
+

+

+Note that all the matches that are found start at the same point in the
+subject. If the pattern
+
+  cat(er(pillar)?)?
+

+is matched against the string "the caterpillar catchment", the result will be
+the three strings "caterpillar", "cater", and "cat" that start at the fifth
+character of the subject. The algorithm does not automatically move on to find
+matches that start at later positions.
+

+

+PCRE's "auto-possessification" optimization usually applies to character
+repeats at the end of a pattern (as well as internally). For example, the
+pattern "a\d+" is compiled as if it were "a\d++" because there is no point
+even considering the possibility of backtracking into the repeated digits. For
+DFA matching, this means that only one possible match is found. If you really
+do want multiple matches in such cases, either use an ungreedy repeat
+("a\d+?") or set the PCRE_NO_AUTO_POSSESS option when compiling.
+

+

+There are a number of features of PCRE regular expressions that are not
+supported by the alternative matching algorithm. They are as follows:
+

+

+1. Because the algorithm finds all possible matches, the greedy or ungreedy
+nature of repetition quantifiers is not relevant. Greedy and ungreedy
+quantifiers are treated in exactly the same way. However, possessive
+quantifiers can make a difference when what follows could also match what is
+quantified, for example in a pattern like this:
+
+  ^a++\w!
+

+This pattern matches "aaab!" but not "aaa!", which would be matched by a
+non-possessive quantifier. Similarly, if an atomic group is present, it is
+matched as if it were a standalone pattern at the current point, and the
+longest match is then "locked in" for the rest of the overall pattern.
+

+

+2. When dealing with multiple paths through the tree simultaneously, it is not
+straightforward to keep track of captured substrings for the different matching
+possibilities, and PCRE's implementation of this algorithm does not attempt to
+do this. This means that no captured substrings are available.
+

+

+3. Because no substrings are captured, back references within the pattern are
+not supported, and cause errors if encountered.
+

+

+4. For the same reason, conditional expressions that use a backreference as the
+condition or test for a specific group recursion are not supported.
+

+

+5. Because many paths through the tree may be active, the \K escape sequence,
+which resets the start of the match when encountered (but may be on some paths
+and not on others), is not supported. It causes an error if encountered.
+

+

+6. Callouts are supported, but the value of the capture_top field is
+always 1, and the value of the capture_last field is always -1.
+

+

+7. The \C escape sequence, which (in the standard algorithm) always matches a
+single data unit, even in UTF-8, UTF-16 or UTF-32 modes, is not supported in
+these modes, because the alternative algorithm moves through the subject string
+one character (not data unit) at a time, for all active paths through the tree.
+

+

+8. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) are not
+supported. (*FAIL) is supported, and behaves like a failing negative assertion.
+

+
ADVANTAGES OF THE ALTERNATIVE ALGORITHM

+

+Using the alternative matching algorithm provides the following advantages:
+

+

+1. All possible matches (at a single point in the subject) are automatically
+found, and in particular, the longest match is found. To find more than one
+match using the standard algorithm, you have to do kludgy things with
+callouts.
+

+

+2. Because the alternative algorithm scans the subject string just once, and
+never needs to backtrack (except for lookbehinds), it is possible to pass very
+long subject strings to the matching function in several pieces, checking for
+partial matching each time. Although it is possible to do multi-segment
+matching using the standard algorithm by retaining partially matched
+substrings, it is more complicated. The
+pcrepartial
+documentation gives details of partial matching and discusses multi-segment
+matching.
+

+
DISADVANTAGES OF THE ALTERNATIVE ALGORITHM

+

+The alternative algorithm suffers from a number of disadvantages:
+

+

+1. It is substantially slower than the standard algorithm. This is partly
+because it has to search for all possible matches, but is also because it is
+less susceptible to optimization.
+

+

+2. Capturing parentheses and back references are not supported.
+

+

+3. Although atomic groups are supported, their use does not provide the
+performance advantage that it does for the standard algorithm.
+

+
AUTHOR

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+
REVISION

+

+Last updated: 12 November 2013
+

+Copyright © 1997-2012 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcrepartial.html b/doc/html/pcrepartial.html
new file mode 100644
index 0000000..4faeafc
--- /dev/null
+++ b/doc/html/pcrepartial.html
@@ -0,0 +1,509 @@
+
+
+pcrepartial specification
+
+
+
pcrepartial man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+
PARTIAL MATCHING IN PCRE

+

+In normal use of PCRE, if the subject string that is passed to a matching
+function matches as far as it goes, but is too short to match the entire
+pattern, PCRE_ERROR_NOMATCH is returned. There are circumstances where it might
+be helpful to distinguish this case from other cases in which there is no
+match.
+

+

+Consider, for example, an application where a human is required to type in data
+for a field with specific formatting requirements. An example might be a date
+in the form ddmmmyy, defined by this pattern:
+
+  ^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$
+

+If the application sees the user's keystrokes one by one, and can check that
+what has been typed so far is potentially valid, it is able to raise an error
+as soon as a mistake is made, by beeping and not reflecting the character that
+has been typed, for example. This immediate feedback is likely to be a better
+user interface than a check that is delayed until the entire string has been
+entered. Partial matching can also be useful when the subject string is very
+long and is not all available at once.
+

+

+PCRE supports partial matching by means of the PCRE_PARTIAL_SOFT and
+PCRE_PARTIAL_HARD options, which can be set when calling any of the matching
+functions. For backwards compatibility, PCRE_PARTIAL is a synonym for
+PCRE_PARTIAL_SOFT. The essential difference between the two options is whether
+or not a partial match is preferred to an alternative complete match, though
+the details differ between the two types of matching function. If both options
+are set, PCRE_PARTIAL_HARD takes precedence.
+

+

+If you want to use partial matching with just-in-time optimized code, you must
+call pcre_study(), pcre16_study() or  pcre32_study() with one
+or both of these options:
+
+  PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+  PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+

+PCRE_STUDY_JIT_COMPILE should also be set if you are going to run non-partial
+matches on the same pattern. If the appropriate JIT study mode has not been set
+for a match, the interpretive matching code is used.
+

+

+Setting a partial matching option disables two of PCRE's standard
+optimizations. PCRE remembers the last literal data unit in a pattern, and
+abandons matching immediately if it is not present in the subject string. This
+optimization cannot be used for a subject string that might match only
+partially. If the pattern was studied, PCRE knows the minimum length of a
+matching string, and does not bother to run the matching function on shorter
+strings. This optimization is also disabled for partial matching.
+

+
PARTIAL MATCHING USING pcre_exec() OR pcre[16|32]_exec()

+

+A partial match occurs during a call to pcre_exec() or
+pcre[16|32]_exec() when the end of the subject string is reached
+successfully, but matching cannot continue because more characters are needed.
+However, at least one character in the subject must have been inspected. This
+character need not form part of the final matched string; lookbehind assertions
+and the \K escape sequence provide ways of inspecting characters before the
+start of a matched substring. The requirement for inspecting at least one
+character exists because an empty string can always be matched; without such a
+restriction there would always be a partial match of an empty string at the end
+of the subject.
+

+

+If there are at least two slots in the offsets vector when a partial match is
+returned, the first slot is set to the offset of the earliest character that
+was inspected. For convenience, the second offset points to the end of the
+subject so that a substring can easily be identified. If there are at least
+three slots in the offsets vector, the third slot is set to the offset of the
+character where matching started.
+

+

+For the majority of patterns, the contents of the first and third slots will be
+the same. However, for patterns that contain lookbehind assertions, or begin
+with \b or \B, characters before the one where matching started may have been
+inspected while carrying out the match. For example, consider this pattern:
+
+  /(?<=abc)123/
+

+This pattern matches "123", but only if it is preceded by "abc". If the subject
+string is "xyzabc12", the first two offsets after a partial match are for the
+substring "abc12", because all these characters were inspected. However, the
+third offset is set to 6, because that is the offset where matching began.
+

+

+What happens when a partial match is identified depends on which of the two
+partial matching options are set.
+

+

+PCRE_PARTIAL_SOFT WITH pcre_exec() OR pcre[16|32]_exec()
+

+

+If PCRE_PARTIAL_SOFT is set when pcre_exec() or pcre[16|32]_exec()
+identifies a partial match, the partial match is remembered, but matching
+continues as normal, and other alternatives in the pattern are tried. If no
+complete match can be found, PCRE_ERROR_PARTIAL is returned instead of
+PCRE_ERROR_NOMATCH.
+

+

+This option is "soft" because it prefers a complete match over a partial match.
+All the various matching items in a pattern behave as if the subject string is
+potentially complete. For example, \z, \Z, and $ match at the end of the
+subject, as normal, and for \b and \B the end of the subject is treated as a
+non-alphanumeric.
+

+

+If there is more than one partial match, the first one that was found provides
+the data that is returned. Consider this pattern:
+
+  /123\w+X|dogY/
+

+If this is matched against the subject string "abc123dog", both
+alternatives fail to match, but the end of the subject is reached during
+matching, so PCRE_ERROR_PARTIAL is returned. The offsets are set to 3 and 9,
+identifying "123dog" as the first partial match that was found. (In this
+example, there are two partial matches, because "dog" on its own partially
+matches the second alternative.)
+

+

+PCRE_PARTIAL_HARD WITH pcre_exec() OR pcre[16|32]_exec()
+

+

+If PCRE_PARTIAL_HARD is set for pcre_exec() or pcre[16|32]_exec(),
+PCRE_ERROR_PARTIAL is returned as soon as a partial match is found, without
+continuing to search for possible complete matches. This option is "hard"
+because it prefers an earlier partial match over a later complete match. For
+this reason, the assumption is made that the end of the supplied subject string
+may not be the true end of the available data, and so, if \z, \Z, \b, \B,
+or $ are encountered at the end of the subject, the result is
+PCRE_ERROR_PARTIAL, provided that at least one character in the subject has
+been inspected.
+

+

+Setting PCRE_PARTIAL_HARD also affects the way UTF-8 and UTF-16
+subject strings are checked for validity. Normally, an invalid sequence
+causes the error PCRE_ERROR_BADUTF8 or PCRE_ERROR_BADUTF16. However, in the
+special case of a truncated character at the end of the subject,
+PCRE_ERROR_SHORTUTF8 or PCRE_ERROR_SHORTUTF16 is returned when
+PCRE_PARTIAL_HARD is set.
+

+

+Comparing hard and soft partial matching
+

+

+The difference between the two partial matching options can be illustrated by a
+pattern such as:
+
+  /dog(sbody)?/
+

+This matches either "dog" or "dogsbody", greedily (that is, it prefers the
+longer string if possible). If it is matched against the string "dog" with
+PCRE_PARTIAL_SOFT, it yields a complete match for "dog". However, if
+PCRE_PARTIAL_HARD is set, the result is PCRE_ERROR_PARTIAL. On the other hand,
+if the pattern is made ungreedy the result is different:
+
+  /dog(sbody)??/
+

+In this case the result is always a complete match because that is found first,
+and matching never continues after finding a complete match. It might be easier
+to follow this explanation by thinking of the two patterns like this:
+
+  /dog(sbody)?/    is the same as  /dogsbody|dog/
+  /dog(sbody)??/   is the same as  /dog|dogsbody/
+

+The second pattern will never match "dogsbody", because it will always find the
+shorter match first.
+

+
PARTIAL MATCHING USING pcre_dfa_exec() OR pcre[16|32]_dfa_exec()

+

+The DFA functions move along the subject string character by character, without
+backtracking, searching for all possible matches simultaneously. If the end of
+the subject is reached before the end of the pattern, there is the possibility
+of a partial match, again provided that at least one character has been
+inspected.
+

+

+When PCRE_PARTIAL_SOFT is set, PCRE_ERROR_PARTIAL is returned only if there
+have been no complete matches. Otherwise, the complete matches are returned.
+However, if PCRE_PARTIAL_HARD is set, a partial match takes precedence over any
+complete matches. The portion of the string that was inspected when the longest
+partial match was found is set as the first matching string, provided there are
+at least two slots in the offsets vector.
+

+

+Because the DFA functions always search for all possible matches, and there is
+no difference between greedy and ungreedy repetition, their behaviour is
+different from the standard functions when PCRE_PARTIAL_HARD is set. Consider
+the string "dog" matched against the ungreedy pattern shown above:
+
+  /dog(sbody)??/
+

+Whereas the standard functions stop as soon as they find the complete match for
+"dog", the DFA functions also find the partial match for "dogsbody", and so
+return that when PCRE_PARTIAL_HARD is set.
+

+
PARTIAL MATCHING AND WORD BOUNDARIES

+

+If a pattern ends with one of sequences \b or \B, which test for word
+boundaries, partial matching with PCRE_PARTIAL_SOFT can give counter-intuitive
+results. Consider this pattern:
+
+  /\bcat\b/
+

+This matches "cat", provided there is a word boundary at either end. If the
+subject string is "the cat", the comparison of the final "t" with a following
+character cannot take place, so a partial match is found. However, normal
+matching carries on, and \b matches at the end of the subject when the last
+character is a letter, so a complete match is found. The result, therefore, is
+not PCRE_ERROR_PARTIAL. Using PCRE_PARTIAL_HARD in this case does yield
+PCRE_ERROR_PARTIAL, because then the partial match takes precedence.
+

+
FORMERLY RESTRICTED PATTERNS

+

+For releases of PCRE prior to 8.00, because of the way certain internal
+optimizations were implemented in the pcre_exec() function, the
+PCRE_PARTIAL option (predecessor of PCRE_PARTIAL_SOFT) could not be used with
+all patterns. From release 8.00 onwards, the restrictions no longer apply, and
+partial matching with can be requested for any pattern.
+

+

+Items that were formerly restricted were repeated single characters and
+repeated metasequences. If PCRE_PARTIAL was set for a pattern that did not
+conform to the restrictions, pcre_exec() returned the error code
+PCRE_ERROR_BADPARTIAL (-13). This error code is no longer in use. The
+PCRE_INFO_OKPARTIAL call to pcre_fullinfo() to find out if a compiled
+pattern can be used for partial matching now always returns 1.
+

+
EXAMPLE OF PARTIAL MATCHING USING PCRETEST

+

+If the escape sequence \P is present in a pcretest data line, the
+PCRE_PARTIAL_SOFT option is used for the match. Here is a run of pcretest
+that uses the date example quoted above:
+
+    re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
+  data> 25jun04\P
+   0: 25jun04
+   1: jun
+  data> 25dec3\P
+  Partial match: 23dec3
+  data> 3ju\P
+  Partial match: 3ju
+  data> 3juj\P
+  No match
+  data> j\P
+  No match
+

+The first data string is matched completely, so pcretest shows the
+matched substrings. The remaining four strings do not match the complete
+pattern, but the first two are partial matches. Similar output is obtained
+if DFA matching is used.
+

+

+If the escape sequence \P is present more than once in a pcretest data
+line, the PCRE_PARTIAL_HARD option is set for the match.
+

+
MULTI-SEGMENT MATCHING WITH pcre_dfa_exec() OR pcre[16|32]_dfa_exec()

+

+When a partial match has been found using a DFA matching function, it is
+possible to continue the match by providing additional subject data and calling
+the function again with the same compiled regular expression, this time setting
+the PCRE_DFA_RESTART option. You must pass the same working space as before,
+because this is where details of the previous partial match are stored. Here is
+an example using pcretest, using the \R escape sequence to set the
+PCRE_DFA_RESTART option (\D specifies the use of the DFA matching function):
+
+    re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
+  data> 23ja\P\D
+  Partial match: 23ja
+  data> n05\R\D
+   0: n05
+

+The first call has "23ja" as the subject, and requests partial matching; the
+second call has "n05" as the subject for the continued (restarted) match.
+Notice that when the match is complete, only the last part is shown; PCRE does
+not retain the previously partially-matched string. It is up to the calling
+program to do that if it needs to.
+

+

+That means that, for an unanchored pattern, if a continued match fails, it is
+not possible to try again at a new starting point. All this facility is capable
+of doing is continuing with the previous match attempt. In the previous
+example, if the second set of data is "ug23" the result is no match, even
+though there would be a match for "aug23" if the entire string were given at
+once. Depending on the application, this may or may not be what you want.
+The only way to allow for starting again at the next character is to retain the
+matched part of the subject and try a new complete match.
+

+

+You can set the PCRE_PARTIAL_SOFT or PCRE_PARTIAL_HARD options with
+PCRE_DFA_RESTART to continue partial matching over multiple segments. This
+facility can be used to pass very long subject strings to the DFA matching
+functions.
+

+
MULTI-SEGMENT MATCHING WITH pcre_exec() OR pcre[16|32]_exec()

+

+From release 8.00, the standard matching functions can also be used to do
+multi-segment matching. Unlike the DFA functions, it is not possible to
+restart the previous match with a new segment of data. Instead, new data must
+be added to the previous subject string, and the entire match re-run, starting
+from the point where the partial match occurred. Earlier data can be discarded.
+

+

+It is best to use PCRE_PARTIAL_HARD in this situation, because it does not
+treat the end of a segment as the end of the subject when matching \z, \Z,
+\b, \B, and $. Consider an unanchored pattern that matches dates:
+
+    re> /\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d/
+  data> The date is 23ja\P\P
+  Partial match: 23ja
+

+At this stage, an application could discard the text preceding "23ja", add on
+text from the next segment, and call the matching function again. Unlike the
+DFA matching functions, the entire matching string must always be available,
+and the complete matching process occurs for each call, so more memory and more
+processing time is needed.
+

+

+Note: If the pattern contains lookbehind assertions, or \K, or starts
+with \b or \B, the string that is returned for a partial match includes
+characters that precede the start of what would be returned for a complete
+match, because it contains all the characters that were inspected during the
+partial match.
+

+
ISSUES WITH MULTI-SEGMENT MATCHING

+

+Certain types of pattern may give problems with multi-segment matching,
+whichever matching function is used.
+

+

+1. If the pattern contains a test for the beginning of a line, you need to pass
+the PCRE_NOTBOL option when the subject string for any call does start at the
+beginning of a line. There is also a PCRE_NOTEOL option, but in practice when
+doing multi-segment matching you should be using PCRE_PARTIAL_HARD, which
+includes the effect of PCRE_NOTEOL.
+

+

+2. Lookbehind assertions that have already been obeyed are catered for in the
+offsets that are returned for a partial match. However a lookbehind assertion
+later in the pattern could require even earlier characters to be inspected. You
+can handle this case by using the PCRE_INFO_MAXLOOKBEHIND option of the
+pcre_fullinfo() or pcre[16|32]_fullinfo() functions to obtain the
+length of the longest lookbehind in the pattern. This length is given in
+characters, not bytes. If you always retain at least that many characters
+before the partially matched string, all should be well. (Of course, near the
+start of the subject, fewer characters may be present; in that case all
+characters should be retained.)
+

+

+From release 8.33, there is a more accurate way of deciding which characters to
+retain. Instead of subtracting the length of the longest lookbehind from the
+earliest inspected character (offsets[0]), the match start position
+(offsets[2]) should be used, and the next match attempt started at the
+offsets[2] character by setting the startoffset argument of
+pcre_exec() or pcre_dfa_exec().
+

+

+For example, if the pattern "(?<=123)abc" is partially
+matched against the string "xx123a", the three offset values returned are 2, 6,
+and 5. This indicates that the matching process that gave a partial match
+started at offset 5, but the characters "123a" were all inspected. The maximum
+lookbehind for that pattern is 3, so taking that away from 5 shows that we need
+only keep "123a", and the next match attempt can be started at offset 3 (that
+is, at "a") when further characters have been added. When the match start is
+not the earliest inspected character, pcretest shows it explicitly:
+
+    re> "(?<=123)abc"
+  data> xx123a\P\P
+  Partial match at offset 5: 123a
+

+

+

+3. Because a partial match must always contain at least one character, what
+might be considered a partial match of an empty string actually gives a "no
+match" result. For example:
+
+    re> /c(?<=abc)x/
+  data> ab\P
+  No match
+

+If the next segment begins "cx", a match should be found, but this will only
+happen if characters from the previous segment are retained. For this reason, a
+"no match" result should be interpreted as "partial match of an empty string"
+when the pattern contains lookbehinds.
+

+

+4. Matching a subject string that is split into multiple segments may not
+always produce exactly the same result as matching over one single long string,
+especially when PCRE_PARTIAL_SOFT is used. The section "Partial Matching and
+Word Boundaries" above describes an issue that arises if the pattern ends with
+\b or \B. Another kind of difference may occur when there are multiple
+matching possibilities, because (for PCRE_PARTIAL_SOFT) a partial match result
+is given only when there are no completed matches. This means that as soon as
+the shortest match has been found, continuation to a new subject segment is no
+longer possible. Consider again this pcretest example:
+
+    re> /dog(sbody)?/
+  data> dogsb\P
+   0: dog
+  data> do\P\D
+  Partial match: do
+  data> gsb\R\P\D
+   0: g
+  data> dogsbody\D
+   0: dogsbody
+   1: dog
+

+The first data line passes the string "dogsb" to a standard matching function,
+setting the PCRE_PARTIAL_SOFT option. Although the string is a partial match
+for "dogsbody", the result is not PCRE_ERROR_PARTIAL, because the shorter
+string "dog" is a complete match. Similarly, when the subject is presented to
+a DFA matching function in several parts ("do" and "gsb" being the first two)
+the match stops when "dog" has been found, and it is not possible to continue.
+On the other hand, if "dogsbody" is presented as a single string, a DFA
+matching function finds both matches.
+

+

+Because of these problems, it is best to use PCRE_PARTIAL_HARD when matching
+multi-segment data. The example above then behaves differently:
+
+    re> /dog(sbody)?/
+  data> dogsb\P\P
+  Partial match: dogsb
+  data> do\P\D
+  Partial match: do
+  data> gsb\R\P\P\D
+  Partial match: gsb
+

+5. Patterns that contain alternatives at the top level which do not all start
+with the same pattern item may not work as expected when PCRE_DFA_RESTART is
+used. For example, consider this pattern:
+
+  1234|3789
+

+If the first part of the subject is "ABC123", a partial match of the first
+alternative is found at offset 3. There is no partial match for the second
+alternative, because such a match does not start at the same point in the
+subject string. Attempting to continue with the string "7890" does not yield a
+match because only those alternatives that match at one point in the subject
+are remembered. The problem arises because the start of the second alternative
+matches within the first alternative. There is no problem with anchored
+patterns or patterns such as:
+
+  1234|ABCD
+

+where no string can be a partial match for both alternatives. This is not a
+problem if a standard matching function is used, because the entire match has
+to be rerun each time:
+
+    re> /1234|3789/
+  data> ABC123\P\P
+  Partial match: 123
+  data> 1237890
+   0: 3789
+

+Of course, instead of using PCRE_DFA_RESTART, the same technique of re-running
+the entire match can also be used with the DFA matching functions. Another
+possibility is to work with two buffers. If a partial match at offset n
+in the first buffer is followed by "no match" when PCRE_DFA_RESTART is used on
+the second buffer, you can then try a new match starting at offset n+1 in
+the first buffer.
+

+
AUTHOR

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+
REVISION

+

+Last updated: 02 July 2013
+

+Copyright © 1997-2013 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcrepattern.html b/doc/html/pcrepattern.html
new file mode 100644
index 0000000..c06d1e0
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@@ -0,0 +1,3235 @@
+
+
+pcrepattern specification
+
+
+
pcrepattern man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+
PCRE REGULAR EXPRESSION DETAILS

+

+The syntax and semantics of the regular expressions that are supported by PCRE
+are described in detail below. There is a quick-reference syntax summary in the
+pcresyntax
+page. PCRE tries to match Perl syntax and semantics as closely as it can. PCRE
+also supports some alternative regular expression syntax (which does not
+conflict with the Perl syntax) in order to provide some compatibility with
+regular expressions in Python, .NET, and Oniguruma.
+

+

+Perl's regular expressions are described in its own documentation, and
+regular expressions in general are covered in a number of books, some of which
+have copious examples. Jeffrey Friedl's "Mastering Regular Expressions",
+published by O'Reilly, covers regular expressions in great detail. This
+description of PCRE's regular expressions is intended as reference material.
+

+

+This document discusses the patterns that are supported by PCRE when one its
+main matching functions, pcre_exec() (8-bit) or pcre[16|32]_exec()
+(16- or 32-bit), is used. PCRE also has alternative matching functions,
+pcre_dfa_exec() and pcre[16|32_dfa_exec(), which match using a
+different algorithm that is not Perl-compatible. Some of the features discussed
+below are not available when DFA matching is used. The advantages and
+disadvantages of the alternative functions, and how they differ from the normal
+functions, are discussed in the
+pcrematching
+page.
+

+
SPECIAL START-OF-PATTERN ITEMS

+

+A number of options that can be passed to pcre_compile() can also be set
+by special items at the start of a pattern. These are not Perl-compatible, but
+are provided to make these options accessible to pattern writers who are not
+able to change the program that processes the pattern. Any number of these
+items may appear, but they must all be together right at the start of the
+pattern string, and the letters must be in upper case.
+

+

+UTF support
+

+

+The original operation of PCRE was on strings of one-byte characters. However,
+there is now also support for UTF-8 strings in the original library, an
+extra library that supports 16-bit and UTF-16 character strings, and a
+third library that supports 32-bit and UTF-32 character strings. To use these
+features, PCRE must be built to include appropriate support. When using UTF
+strings you must either call the compiling function with the PCRE_UTF8,
+PCRE_UTF16, or PCRE_UTF32 option, or the pattern must start with one of
+these special sequences:
+
+  (*UTF8)
+  (*UTF16)
+  (*UTF32)
+  (*UTF)
+

+(*UTF) is a generic sequence that can be used with any of the libraries.
+Starting a pattern with such a sequence is equivalent to setting the relevant
+option. How setting a UTF mode affects pattern matching is mentioned in several
+places below. There is also a summary of features in the
+pcreunicode
+page.
+

+

+Some applications that allow their users to supply patterns may wish to
+restrict them to non-UTF data for security reasons. If the PCRE_NEVER_UTF
+option is set at compile time, (*UTF) etc. are not allowed, and their
+appearance causes an error.
+

+

+Unicode property support
+

+

+Another special sequence that may appear at the start of a pattern is (*UCP).
+This has the same effect as setting the PCRE_UCP option: it causes sequences
+such as \d and \w to use Unicode properties to determine character types,
+instead of recognizing only characters with codes less than 128 via a lookup
+table.
+

+

+Disabling auto-possessification
+

+

+If a pattern starts with (*NO_AUTO_POSSESS), it has the same effect as setting
+the PCRE_NO_AUTO_POSSESS option at compile time. This stops PCRE from making
+quantifiers possessive when what follows cannot match the repeated item. For
+example, by default a+b is treated as a++b. For more details, see the
+pcreapi
+documentation.
+

+

+Disabling start-up optimizations
+

+

+If a pattern starts with (*NO_START_OPT), it has the same effect as setting the
+PCRE_NO_START_OPTIMIZE option either at compile or matching time. This disables
+several optimizations for quickly reaching "no match" results. For more
+details, see the
+pcreapi
+documentation.
+

+

+Newline conventions
+

+

+PCRE supports five different conventions for indicating line breaks in
+strings: a single CR (carriage return) character, a single LF (linefeed)
+character, the two-character sequence CRLF, any of the three preceding, or any
+Unicode newline sequence. The
+pcreapi
+page has
+further discussion
+about newlines, and shows how to set the newline convention in the
+options arguments for the compiling and matching functions.
+

+

+It is also possible to specify a newline convention by starting a pattern
+string with one of the following five sequences:
+
+  (*CR)        carriage return
+  (*LF)        linefeed
+  (*CRLF)      carriage return, followed by linefeed
+  (*ANYCRLF)   any of the three above
+  (*ANY)       all Unicode newline sequences
+

+These override the default and the options given to the compiling function. For
+example, on a Unix system where LF is the default newline sequence, the pattern
+
+  (*CR)a.b
+

+changes the convention to CR. That pattern matches "a\nb" because LF is no
+longer a newline. If more than one of these settings is present, the last one
+is used.
+

+

+The newline convention affects where the circumflex and dollar assertions are
+true. It also affects the interpretation of the dot metacharacter when
+PCRE_DOTALL is not set, and the behaviour of \N. However, it does not affect
+what the \R escape sequence matches. By default, this is any Unicode newline
+sequence, for Perl compatibility. However, this can be changed; see the
+description of \R in the section entitled
+"Newline sequences"
+below. A change of \R setting can be combined with a change of newline
+convention.
+

+

+Setting match and recursion limits
+

+

+The caller of pcre_exec() can set a limit on the number of times the
+internal match() function is called and on the maximum depth of
+recursive calls. These facilities are provided to catch runaway matches that
+are provoked by patterns with huge matching trees (a typical example is a
+pattern with nested unlimited repeats) and to avoid running out of system stack
+by too much recursion. When one of these limits is reached, pcre_exec()
+gives an error return. The limits can also be set by items at the start of the
+pattern of the form
+
+  (*LIMIT_MATCH=d)
+  (*LIMIT_RECURSION=d)
+

+where d is any number of decimal digits. However, the value of the setting must
+be less than the value set (or defaulted) by the caller of pcre_exec()
+for it to have any effect. In other words, the pattern writer can lower the
+limits set by the programmer, but not raise them. If there is more than one
+setting of one of these limits, the lower value is used.
+

+
EBCDIC CHARACTER CODES

+

+PCRE can be compiled to run in an environment that uses EBCDIC as its character
+code rather than ASCII or Unicode (typically a mainframe system). In the
+sections below, character code values are ASCII or Unicode; in an EBCDIC
+environment these characters may have different code values, and there are no
+code points greater than 255.
+

+
CHARACTERS AND METACHARACTERS

+

+A regular expression is a pattern that is matched against a subject string from
+left to right. Most characters stand for themselves in a pattern, and match the
+corresponding characters in the subject. As a trivial example, the pattern
+
+  The quick brown fox
+

+matches a portion of a subject string that is identical to itself. When
+caseless matching is specified (the PCRE_CASELESS option), letters are matched
+independently of case. In a UTF mode, PCRE always understands the concept of
+case for characters whose values are less than 128, so caseless matching is
+always possible. For characters with higher values, the concept of case is
+supported if PCRE is compiled with Unicode property support, but not otherwise.
+If you want to use caseless matching for characters 128 and above, you must
+ensure that PCRE is compiled with Unicode property support as well as with
+UTF support.
+

+

+The power of regular expressions comes from the ability to include alternatives
+and repetitions in the pattern. These are encoded in the pattern by the use of
+metacharacters, which do not stand for themselves but instead are
+interpreted in some special way.
+

+

+There are two different sets of metacharacters: those that are recognized
+anywhere in the pattern except within square brackets, and those that are
+recognized within square brackets. Outside square brackets, the metacharacters
+are as follows:
+
+  \      general escape character with several uses
+  ^      assert start of string (or line, in multiline mode)
+  $      assert end of string (or line, in multiline mode)
+  .      match any character except newline (by default)
+  [      start character class definition
+  |      start of alternative branch
+  (      start subpattern
+  )      end subpattern
+  ?      extends the meaning of (
+         also 0 or 1 quantifier
+         also quantifier minimizer
+  *      0 or more quantifier
+  +      1 or more quantifier
+         also "possessive quantifier"
+  {      start min/max quantifier
+

+Part of a pattern that is in square brackets is called a "character class". In
+a character class the only metacharacters are:
+
+  \      general escape character
+  ^      negate the class, but only if the first character
+  -      indicates character range
+  [      POSIX character class (only if followed by POSIX syntax)
+  ]      terminates the character class
+

+The following sections describe the use of each of the metacharacters.
+

+
BACKSLASH

+

+The backslash character has several uses. Firstly, if it is followed by a
+character that is not a number or a letter, it takes away any special meaning
+that character may have. This use of backslash as an escape character applies
+both inside and outside character classes.
+

+

+For example, if you want to match a * character, you write \* in the pattern.
+This escaping action applies whether or not the following character would
+otherwise be interpreted as a metacharacter, so it is always safe to precede a
+non-alphanumeric with backslash to specify that it stands for itself. In
+particular, if you want to match a backslash, you write \\.
+

+

+In a UTF mode, only ASCII numbers and letters have any special meaning after a
+backslash. All other characters (in particular, those whose codepoints are
+greater than 127) are treated as literals.
+

+

+If a pattern is compiled with the PCRE_EXTENDED option, most white space in the
+pattern (other than in a character class), and characters between a # outside a
+character class and the next newline, inclusive, are ignored. An escaping
+backslash can be used to include a white space or # character as part of the
+pattern.
+

+

+If you want to remove the special meaning from a sequence of characters, you
+can do so by putting them between \Q and \E. This is different from Perl in
+that $ and @ are handled as literals in \Q...\E sequences in PCRE, whereas in
+Perl, $ and @ cause variable interpolation. Note the following examples:
+
+  Pattern            PCRE matches   Perl matches
+
+  \Qabc$xyz\E        abc$xyz        abc followed by the contents of $xyz
+  \Qabc\$xyz\E       abc\$xyz       abc\$xyz
+  \Qabc\E\$\Qxyz\E   abc$xyz        abc$xyz
+

+The \Q...\E sequence is recognized both inside and outside character classes.
+An isolated \E that is not preceded by \Q is ignored. If \Q is not followed
+by \E later in the pattern, the literal interpretation continues to the end of
+the pattern (that is, \E is assumed at the end). If the isolated \Q is inside
+a character class, this causes an error, because the character class is not
+terminated.
+

+

+Non-printing characters
+

+

+A second use of backslash provides a way of encoding non-printing characters
+in patterns in a visible manner. There is no restriction on the appearance of
+non-printing characters, apart from the binary zero that terminates a pattern,
+but when a pattern is being prepared by text editing, it is often easier to use
+one of the following escape sequences than the binary character it represents:
+
+  \a        alarm, that is, the BEL character (hex 07)
+  \cx       "control-x", where x is any ASCII character
+  \e        escape (hex 1B)
+  \f        form feed (hex 0C)
+  \n        linefeed (hex 0A)
+  \r        carriage return (hex 0D)
+  \t        tab (hex 09)
+  \0dd      character with octal code 0dd
+  \ddd      character with octal code ddd, or back reference
+  \o{ddd..} character with octal code ddd..
+  \xhh      character with hex code hh
+  \x{hhh..} character with hex code hhh.. (non-JavaScript mode)
+  \uhhhh    character with hex code hhhh (JavaScript mode only)
+

+The precise effect of \cx on ASCII characters is as follows: if x is a lower
+case letter, it is converted to upper case. Then bit 6 of the character (hex
+40) is inverted. Thus \cA to \cZ become hex 01 to hex 1A (A is 41, Z is 5A),
+but \c{ becomes hex 3B ({ is 7B), and \c; becomes hex 7B (; is 3B). If the
+data item (byte or 16-bit value) following \c has a value greater than 127, a
+compile-time error occurs. This locks out non-ASCII characters in all modes.
+

+

+The \c facility was designed for use with ASCII characters, but with the
+extension to Unicode it is even less useful than it once was. It is, however,
+recognized when PCRE is compiled in EBCDIC mode, where data items are always
+bytes. In this mode, all values are valid after \c. If the next character is a
+lower case letter, it is converted to upper case. Then the 0xc0 bits of the
+byte are inverted. Thus \cA becomes hex 01, as in ASCII (A is C1), but because
+the EBCDIC letters are disjoint, \cZ becomes hex 29 (Z is E9), and other
+characters also generate different values.
+

+

+After \0 up to two further octal digits are read. If there are fewer than two
+digits, just those that are present are used. Thus the sequence \0\x\07
+specifies two binary zeros followed by a BEL character (code value 7). Make
+sure you supply two digits after the initial zero if the pattern character that
+follows is itself an octal digit.
+

+

+The escape \o must be followed by a sequence of octal digits, enclosed in
+braces. An error occurs if this is not the case. This escape is a recent
+addition to Perl; it provides way of specifying character code points as octal
+numbers greater than 0777, and it also allows octal numbers and back references
+to be unambiguously specified.
+

+

+For greater clarity and unambiguity, it is best to avoid following \ by a
+digit greater than zero. Instead, use \o{} or \x{} to specify character
+numbers, and \g{} to specify back references. The following paragraphs
+describe the old, ambiguous syntax.
+

+

+The handling of a backslash followed by a digit other than 0 is complicated,
+and Perl has changed in recent releases, causing PCRE also to change. Outside a
+character class, PCRE reads the digit and any following digits as a decimal
+number. If the number is less than 8, or if there have been at least that many
+previous capturing left parentheses in the expression, the entire sequence is
+taken as a back reference. A description of how this works is given
+later,
+following the discussion of
+parenthesized subpatterns.
+

+

+Inside a character class, or if the decimal number following \ is greater than
+7 and there have not been that many capturing subpatterns, PCRE handles \8 and
+\9 as the literal characters "8" and "9", and otherwise re-reads up to three
+octal digits following the backslash, using them to generate a data character.
+Any subsequent digits stand for themselves. For example:
+
+  \040   is another way of writing an ASCII space
+  \40    is the same, provided there are fewer than 40 previous capturing subpatterns
+  \7     is always a back reference
+  \11    might be a back reference, or another way of writing a tab
+  \011   is always a tab
+  \0113  is a tab followed by the character "3"
+  \113   might be a back reference, otherwise the character with octal code 113
+  \377   might be a back reference, otherwise the value 255 (decimal)
+  \81    is either a back reference, or the two characters "8" and "1"
+

+Note that octal values of 100 or greater that are specified using this syntax
+must not be introduced by a leading zero, because no more than three octal
+digits are ever read.
+

+

+By default, after \x that is not followed by {, from zero to two hexadecimal
+digits are read (letters can be in upper or lower case). Any number of
+hexadecimal digits may appear between \x{ and }. If a character other than
+a hexadecimal digit appears between \x{ and }, or if there is no terminating
+}, an error occurs.
+

+

+If the PCRE_JAVASCRIPT_COMPAT option is set, the interpretation of \x is
+as just described only when it is followed by two hexadecimal digits.
+Otherwise, it matches a literal "x" character. In JavaScript mode, support for
+code points greater than 256 is provided by \u, which must be followed by
+four hexadecimal digits; otherwise it matches a literal "u" character.
+

+

+Characters whose value is less than 256 can be defined by either of the two
+syntaxes for \x (or by \u in JavaScript mode). There is no difference in the
+way they are handled. For example, \xdc is exactly the same as \x{dc} (or
+\u00dc in JavaScript mode).
+

+

+Constraints on character values
+

+

+Characters that are specified using octal or hexadecimal numbers are
+limited to certain values, as follows:
+
+  8-bit non-UTF mode    less than 0x100
+  8-bit UTF-8 mode      less than 0x10ffff and a valid codepoint
+  16-bit non-UTF mode   less than 0x10000
+  16-bit UTF-16 mode    less than 0x10ffff and a valid codepoint
+  32-bit non-UTF mode   less than 0x100000000
+  32-bit UTF-32 mode    less than 0x10ffff and a valid codepoint
+

+Invalid Unicode codepoints are the range 0xd800 to 0xdfff (the so-called
+"surrogate" codepoints), and 0xffef.
+

+

+Escape sequences in character classes
+

+

+All the sequences that define a single character value can be used both inside
+and outside character classes. In addition, inside a character class, \b is
+interpreted as the backspace character (hex 08).
+

+

+\N is not allowed in a character class. \B, \R, and \X are not special
+inside a character class. Like other unrecognized escape sequences, they are
+treated as the literal characters "B", "R", and "X" by default, but cause an
+error if the PCRE_EXTRA option is set. Outside a character class, these
+sequences have different meanings.
+

+

+Unsupported escape sequences
+

+

+In Perl, the sequences \l, \L, \u, and \U are recognized by its string
+handler and used to modify the case of following characters. By default, PCRE
+does not support these escape sequences. However, if the PCRE_JAVASCRIPT_COMPAT
+option is set, \U matches a "U" character, and \u can be used to define a
+character by code point, as described in the previous section.
+

+

+Absolute and relative back references
+

+

+The sequence \g followed by an unsigned or a negative number, optionally
+enclosed in braces, is an absolute or relative back reference. A named back
+reference can be coded as \g{name}. Back references are discussed
+later,
+following the discussion of
+parenthesized subpatterns.
+

+

+Absolute and relative subroutine calls
+

+

+For compatibility with Oniguruma, the non-Perl syntax \g followed by a name or
+a number enclosed either in angle brackets or single quotes, is an alternative
+syntax for referencing a subpattern as a "subroutine". Details are discussed
+later.
+Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not
+synonymous. The former is a back reference; the latter is a
+subroutine
+call.
+

+

+Generic character types
+

+

+Another use of backslash is for specifying generic character types:
+
+  \d     any decimal digit
+  \D     any character that is not a decimal digit
+  \h     any horizontal white space character
+  \H     any character that is not a horizontal white space character
+  \s     any white space character
+  \S     any character that is not a white space character
+  \v     any vertical white space character
+  \V     any character that is not a vertical white space character
+  \w     any "word" character
+  \W     any "non-word" character
+

+There is also the single sequence \N, which matches a non-newline character.
+This is the same as
+the "." metacharacter
+when PCRE_DOTALL is not set. Perl also uses \N to match characters by name;
+PCRE does not support this.
+

+

+Each pair of lower and upper case escape sequences partitions the complete set
+of characters into two disjoint sets. Any given character matches one, and only
+one, of each pair. The sequences can appear both inside and outside character
+classes. They each match one character of the appropriate type. If the current
+matching point is at the end of the subject string, all of them fail, because
+there is no character to match.
+

+

+For compatibility with Perl, \s did not used to match the VT character (code
+11), which made it different from the the POSIX "space" class. However, Perl
+added VT at release 5.18, and PCRE followed suit at release 8.34. The default
+\s characters are now HT (9), LF (10), VT (11), FF (12), CR (13), and space
+(32), which are defined as white space in the "C" locale. This list may vary if
+locale-specific matching is taking place. For example, in some locales the
+"non-breaking space" character (\xA0) is recognized as white space, and in
+others the VT character is not.
+

+

+A "word" character is an underscore or any character that is a letter or digit.
+By default, the definition of letters and digits is controlled by PCRE's
+low-valued character tables, and may vary if locale-specific matching is taking
+place (see
+"Locale support"
+in the
+pcreapi
+page). For example, in a French locale such as "fr_FR" in Unix-like systems,
+or "french" in Windows, some character codes greater than 127 are used for
+accented letters, and these are then matched by \w. The use of locales with
+Unicode is discouraged.
+

+

+By default, characters whose code points are greater than 127 never match \d,
+\s, or \w, and always match \D, \S, and \W, although this may vary for
+characters in the range 128-255 when locale-specific matching is happening.
+These escape sequences retain their original meanings from before Unicode
+support was available, mainly for efficiency reasons. If PCRE is compiled with
+Unicode property support, and the PCRE_UCP option is set, the behaviour is
+changed so that Unicode properties are used to determine character types, as
+follows:
+
+  \d  any character that matches \p{Nd} (decimal digit)
+  \s  any character that matches \p{Z} or \h or \v
+  \w  any character that matches \p{L} or \p{N}, plus underscore
+

+The upper case escapes match the inverse sets of characters. Note that \d
+matches only decimal digits, whereas \w matches any Unicode digit, as well as
+any Unicode letter, and underscore. Note also that PCRE_UCP affects \b, and
+\B because they are defined in terms of \w and \W. Matching these sequences
+is noticeably slower when PCRE_UCP is set.
+

+

+The sequences \h, \H, \v, and \V are features that were added to Perl at
+release 5.10. In contrast to the other sequences, which match only ASCII
+characters by default, these always match certain high-valued code points,
+whether or not PCRE_UCP is set. The horizontal space characters are:
+
+  U+0009     Horizontal tab (HT)
+  U+0020     Space
+  U+00A0     Non-break space
+  U+1680     Ogham space mark
+  U+180E     Mongolian vowel separator
+  U+2000     En quad
+  U+2001     Em quad
+  U+2002     En space
+  U+2003     Em space
+  U+2004     Three-per-em space
+  U+2005     Four-per-em space
+  U+2006     Six-per-em space
+  U+2007     Figure space
+  U+2008     Punctuation space
+  U+2009     Thin space
+  U+200A     Hair space
+  U+202F     Narrow no-break space
+  U+205F     Medium mathematical space
+  U+3000     Ideographic space
+

+The vertical space characters are:
+
+  U+000A     Linefeed (LF)
+  U+000B     Vertical tab (VT)
+  U+000C     Form feed (FF)
+  U+000D     Carriage return (CR)
+  U+0085     Next line (NEL)
+  U+2028     Line separator
+  U+2029     Paragraph separator
+

+In 8-bit, non-UTF-8 mode, only the characters with codepoints less than 256 are
+relevant.
+

+

+Newline sequences
+

+

+Outside a character class, by default, the escape sequence \R matches any
+Unicode newline sequence. In 8-bit non-UTF-8 mode \R is equivalent to the
+following:
+
+  (?>\r\n|\n|\x0b|\f|\r|\x85)
+

+This is an example of an "atomic group", details of which are given
+below.
+This particular group matches either the two-character sequence CR followed by
+LF, or one of the single characters LF (linefeed, U+000A), VT (vertical tab,
+U+000B), FF (form feed, U+000C), CR (carriage return, U+000D), or NEL (next
+line, U+0085). The two-character sequence is treated as a single unit that
+cannot be split.
+

+

+In other modes, two additional characters whose codepoints are greater than 255
+are added: LS (line separator, U+2028) and PS (paragraph separator, U+2029).
+Unicode character property support is not needed for these characters to be
+recognized.
+

+

+It is possible to restrict \R to match only CR, LF, or CRLF (instead of the
+complete set of Unicode line endings) by setting the option PCRE_BSR_ANYCRLF
+either at compile time or when the pattern is matched. (BSR is an abbrevation
+for "backslash R".) This can be made the default when PCRE is built; if this is
+the case, the other behaviour can be requested via the PCRE_BSR_UNICODE option.
+It is also possible to specify these settings by starting a pattern string with
+one of the following sequences:
+
+  (*BSR_ANYCRLF)   CR, LF, or CRLF only
+  (*BSR_UNICODE)   any Unicode newline sequence
+

+These override the default and the options given to the compiling function, but
+they can themselves be overridden by options given to a matching function. Note
+that these special settings, which are not Perl-compatible, are recognized only
+at the very start of a pattern, and that they must be in upper case. If more
+than one of them is present, the last one is used. They can be combined with a
+change of newline convention; for example, a pattern can start with:
+
+  (*ANY)(*BSR_ANYCRLF)
+

+They can also be combined with the (*UTF8), (*UTF16), (*UTF32), (*UTF) or
+(*UCP) special sequences. Inside a character class, \R is treated as an
+unrecognized escape sequence, and so matches the letter "R" by default, but
+causes an error if PCRE_EXTRA is set.
+

+

+Unicode character properties
+

+

+When PCRE is built with Unicode character property support, three additional
+escape sequences that match characters with specific properties are available.
+When in 8-bit non-UTF-8 mode, these sequences are of course limited to testing
+characters whose codepoints are less than 256, but they do work in this mode.
+The extra escape sequences are:
+
+  \p{xx}   a character with the xx property
+  \P{xx}   a character without the xx property
+  \X       a Unicode extended grapheme cluster
+

+The property names represented by xx above are limited to the Unicode
+script names, the general category properties, "Any", which matches any
+character (including newline), and some special PCRE properties (described
+in the
+next section).
+Other Perl properties such as "InMusicalSymbols" are not currently supported by
+PCRE. Note that \P{Any} does not match any characters, so always causes a
+match failure.
+

+

+Sets of Unicode characters are defined as belonging to certain scripts. A
+character from one of these sets can be matched using a script name. For
+example:
+
+  \p{Greek}
+  \P{Han}
+

+Those that are not part of an identified script are lumped together as
+"Common". The current list of scripts is:
+

+

+Arabic,
+Armenian,
+Avestan,
+Balinese,
+Bamum,
+Batak,
+Bengali,
+Bopomofo,
+Brahmi,
+Braille,
+Buginese,
+Buhid,
+Canadian_Aboriginal,
+Carian,
+Chakma,
+Cham,
+Cherokee,
+Common,
+Coptic,
+Cuneiform,
+Cypriot,
+Cyrillic,
+Deseret,
+Devanagari,
+Egyptian_Hieroglyphs,
+Ethiopic,
+Georgian,
+Glagolitic,
+Gothic,
+Greek,
+Gujarati,
+Gurmukhi,
+Han,
+Hangul,
+Hanunoo,
+Hebrew,
+Hiragana,
+Imperial_Aramaic,
+Inherited,
+Inscriptional_Pahlavi,
+Inscriptional_Parthian,
+Javanese,
+Kaithi,
+Kannada,
+Katakana,
+Kayah_Li,
+Kharoshthi,
+Khmer,
+Lao,
+Latin,
+Lepcha,
+Limbu,
+Linear_B,
+Lisu,
+Lycian,
+Lydian,
+Malayalam,
+Mandaic,
+Meetei_Mayek,
+Meroitic_Cursive,
+Meroitic_Hieroglyphs,
+Miao,
+Mongolian,
+Myanmar,
+New_Tai_Lue,
+Nko,
+Ogham,
+Old_Italic,
+Old_Persian,
+Old_South_Arabian,
+Old_Turkic,
+Ol_Chiki,
+Oriya,
+Osmanya,
+Phags_Pa,
+Phoenician,
+Rejang,
+Runic,
+Samaritan,
+Saurashtra,
+Sharada,
+Shavian,
+Sinhala,
+Sora_Sompeng,
+Sundanese,
+Syloti_Nagri,
+Syriac,
+Tagalog,
+Tagbanwa,
+Tai_Le,
+Tai_Tham,
+Tai_Viet,
+Takri,
+Tamil,
+Telugu,
+Thaana,
+Thai,
+Tibetan,
+Tifinagh,
+Ugaritic,
+Vai,
+Yi.
+

+

+Each character has exactly one Unicode general category property, specified by
+a two-letter abbreviation. For compatibility with Perl, negation can be
+specified by including a circumflex between the opening brace and the property
+name. For example, \p{^Lu} is the same as \P{Lu}.
+

+

+If only one letter is specified with \p or \P, it includes all the general
+category properties that start with that letter. In this case, in the absence
+of negation, the curly brackets in the escape sequence are optional; these two
+examples have the same effect:
+
+  \p{L}
+  \pL
+

+The following general category property codes are supported:
+
+  C     Other
+  Cc    Control
+  Cf    Format
+  Cn    Unassigned
+  Co    Private use
+  Cs    Surrogate
+
+  L     Letter
+  Ll    Lower case letter
+  Lm    Modifier letter
+  Lo    Other letter
+  Lt    Title case letter
+  Lu    Upper case letter
+
+  M     Mark
+  Mc    Spacing mark
+  Me    Enclosing mark
+  Mn    Non-spacing mark
+
+  N     Number
+  Nd    Decimal number
+  Nl    Letter number
+  No    Other number
+
+  P     Punctuation
+  Pc    Connector punctuation
+  Pd    Dash punctuation
+  Pe    Close punctuation
+  Pf    Final punctuation
+  Pi    Initial punctuation
+  Po    Other punctuation
+  Ps    Open punctuation
+
+  S     Symbol
+  Sc    Currency symbol
+  Sk    Modifier symbol
+  Sm    Mathematical symbol
+  So    Other symbol
+
+  Z     Separator
+  Zl    Line separator
+  Zp    Paragraph separator
+  Zs    Space separator
+

+The special property L& is also supported: it matches a character that has
+the Lu, Ll, or Lt property, in other words, a letter that is not classified as
+a modifier or "other".
+

+

+The Cs (Surrogate) property applies only to characters in the range U+D800 to
+U+DFFF. Such characters are not valid in Unicode strings and so
+cannot be tested by PCRE, unless UTF validity checking has been turned off
+(see the discussion of PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK and
+PCRE_NO_UTF32_CHECK in the
+pcreapi
+page). Perl does not support the Cs property.
+

+

+The long synonyms for property names that Perl supports (such as \p{Letter})
+are not supported by PCRE, nor is it permitted to prefix any of these
+properties with "Is".
+

+

+No character that is in the Unicode table has the Cn (unassigned) property.
+Instead, this property is assumed for any code point that is not in the
+Unicode table.
+

+

+Specifying caseless matching does not affect these escape sequences. For
+example, \p{Lu} always matches only upper case letters. This is different from
+the behaviour of current versions of Perl.
+

+

+Matching characters by Unicode property is not fast, because PCRE has to do a
+multistage table lookup in order to find a character's property. That is why
+the traditional escape sequences such as \d and \w do not use Unicode
+properties in PCRE by default, though you can make them do so by setting the
+PCRE_UCP option or by starting the pattern with (*UCP).
+

+

+Extended grapheme clusters
+

+

+The \X escape matches any number of Unicode characters that form an "extended
+grapheme cluster", and treats the sequence as an atomic group
+(see below).
+Up to and including release 8.31, PCRE matched an earlier, simpler definition
+that was equivalent to
+
+  (?>\PM\pM*)
+

+That is, it matched a character without the "mark" property, followed by zero
+or more characters with the "mark" property. Characters with the "mark"
+property are typically non-spacing accents that affect the preceding character.
+

+

+This simple definition was extended in Unicode to include more complicated
+kinds of composite character by giving each character a grapheme breaking
+property, and creating rules that use these properties to define the boundaries
+of extended grapheme clusters. In releases of PCRE later than 8.31, \X matches
+one of these clusters.
+

+

+\X always matches at least one character. Then it decides whether to add
+additional characters according to the following rules for ending a cluster:
+

+

+1. End at the end of the subject string.
+

+

+2. Do not end between CR and LF; otherwise end after any control character.
+

+

+3. Do not break Hangul (a Korean script) syllable sequences. Hangul characters
+are of five types: L, V, T, LV, and LVT. An L character may be followed by an
+L, V, LV, or LVT character; an LV or V character may be followed by a V or T
+character; an LVT or T character may be follwed only by a T character.
+

+

+4. Do not end before extending characters or spacing marks. Characters with
+the "mark" property always have the "extend" grapheme breaking property.
+

+

+5. Do not end after prepend characters.
+

+

+6. Otherwise, end the cluster.
+

+

+PCRE's additional properties
+

+

+As well as the standard Unicode properties described above, PCRE supports four
+more that make it possible to convert traditional escape sequences such as \w
+and \s to use Unicode properties. PCRE uses these non-standard, non-Perl
+properties internally when PCRE_UCP is set. However, they may also be used
+explicitly. These properties are:
+
+  Xan   Any alphanumeric character
+  Xps   Any POSIX space character
+  Xsp   Any Perl space character
+  Xwd   Any Perl "word" character
+

+Xan matches characters that have either the L (letter) or the N (number)
+property. Xps matches the characters tab, linefeed, vertical tab, form feed, or
+carriage return, and any other character that has the Z (separator) property.
+Xsp is the same as Xps; it used to exclude vertical tab, for Perl
+compatibility, but Perl changed, and so PCRE followed at release 8.34. Xwd
+matches the same characters as Xan, plus underscore.
+

+

+There is another non-standard property, Xuc, which matches any character that
+can be represented by a Universal Character Name in C++ and other programming
+languages. These are the characters $, @, ` (grave accent), and all characters
+with Unicode code points greater than or equal to U+00A0, except for the
+surrogates U+D800 to U+DFFF. Note that most base (ASCII) characters are
+excluded. (Universal Character Names are of the form \uHHHH or \UHHHHHHHH
+where H is a hexadecimal digit. Note that the Xuc property does not match these
+sequences but the characters that they represent.)
+

+

+Resetting the match start
+

+

+The escape sequence \K causes any previously matched characters not to be
+included in the final matched sequence. For example, the pattern:
+
+  foo\Kbar
+

+matches "foobar", but reports that it has matched "bar". This feature is
+similar to a lookbehind assertion
+(described below).
+However, in this case, the part of the subject before the real match does not
+have to be of fixed length, as lookbehind assertions do. The use of \K does
+not interfere with the setting of
+captured substrings.
+For example, when the pattern
+
+  (foo)\Kbar
+

+matches "foobar", the first substring is still set to "foo".
+

+

+Perl documents that the use of \K within assertions is "not well defined". In
+PCRE, \K is acted upon when it occurs inside positive assertions, but is
+ignored in negative assertions. Note that when a pattern such as (?=ab\K)
+matches, the reported start of the match can be greater than the end of the
+match.
+

+

+Simple assertions
+

+

+The final use of backslash is for certain simple assertions. An assertion
+specifies a condition that has to be met at a particular point in a match,
+without consuming any characters from the subject string. The use of
+subpatterns for more complicated assertions is described
+below.
+The backslashed assertions are:
+
+  \b     matches at a word boundary
+  \B     matches when not at a word boundary
+  \A     matches at the start of the subject
+  \Z     matches at the end of the subject
+          also matches before a newline at the end of the subject
+  \z     matches only at the end of the subject
+  \G     matches at the first matching position in the subject
+

+Inside a character class, \b has a different meaning; it matches the backspace
+character. If any other of these assertions appears in a character class, by
+default it matches the corresponding literal character (for example, \B
+matches the letter B). However, if the PCRE_EXTRA option is set, an "invalid
+escape sequence" error is generated instead.
+

+

+A word boundary is a position in the subject string where the current character
+and the previous character do not both match \w or \W (i.e. one matches
+\w and the other matches \W), or the start or end of the string if the
+first or last character matches \w, respectively. In a UTF mode, the meanings
+of \w and \W can be changed by setting the PCRE_UCP option. When this is
+done, it also affects \b and \B. Neither PCRE nor Perl has a separate "start
+of word" or "end of word" metasequence. However, whatever follows \b normally
+determines which it is. For example, the fragment \ba matches "a" at the start
+of a word.
+

+

+The \A, \Z, and \z assertions differ from the traditional circumflex and
+dollar (described in the next section) in that they only ever match at the very
+start and end of the subject string, whatever options are set. Thus, they are
+independent of multiline mode. These three assertions are not affected by the
+PCRE_NOTBOL or PCRE_NOTEOL options, which affect only the behaviour of the
+circumflex and dollar metacharacters. However, if the startoffset
+argument of pcre_exec() is non-zero, indicating that matching is to start
+at a point other than the beginning of the subject, \A can never match. The
+difference between \Z and \z is that \Z matches before a newline at the end
+of the string as well as at the very end, whereas \z matches only at the end.
+

+

+The \G assertion is true only when the current matching position is at the
+start point of the match, as specified by the startoffset argument of
+pcre_exec(). It differs from \A when the value of startoffset is
+non-zero. By calling pcre_exec() multiple times with appropriate
+arguments, you can mimic Perl's /g option, and it is in this kind of
+implementation where \G can be useful.
+

+

+Note, however, that PCRE's interpretation of \G, as the start of the current
+match, is subtly different from Perl's, which defines it as the end of the
+previous match. In Perl, these can be different when the previously matched
+string was empty. Because PCRE does just one match at a time, it cannot
+reproduce this behaviour.
+

+

+If all the alternatives of a pattern begin with \G, the expression is anchored
+to the starting match position, and the "anchored" flag is set in the compiled
+regular expression.
+

+
CIRCUMFLEX AND DOLLAR

+

+The circumflex and dollar metacharacters are zero-width assertions. That is,
+they test for a particular condition being true without consuming any
+characters from the subject string.
+

+

+Outside a character class, in the default matching mode, the circumflex
+character is an assertion that is true only if the current matching point is at
+the start of the subject string. If the startoffset argument of
+pcre_exec() is non-zero, circumflex can never match if the PCRE_MULTILINE
+option is unset. Inside a character class, circumflex has an entirely different
+meaning
+(see below).
+

+

+Circumflex need not be the first character of the pattern if a number of
+alternatives are involved, but it should be the first thing in each alternative
+in which it appears if the pattern is ever to match that branch. If all
+possible alternatives start with a circumflex, that is, if the pattern is
+constrained to match only at the start of the subject, it is said to be an
+"anchored" pattern. (There are also other constructs that can cause a pattern
+to be anchored.)
+

+

+The dollar character is an assertion that is true only if the current matching
+point is at the end of the subject string, or immediately before a newline at
+the end of the string (by default). Note, however, that it does not actually
+match the newline. Dollar need not be the last character of the pattern if a
+number of alternatives are involved, but it should be the last item in any
+branch in which it appears. Dollar has no special meaning in a character class.
+

+

+The meaning of dollar can be changed so that it matches only at the very end of
+the string, by setting the PCRE_DOLLAR_ENDONLY option at compile time. This
+does not affect the \Z assertion.
+

+

+The meanings of the circumflex and dollar characters are changed if the
+PCRE_MULTILINE option is set. When this is the case, a circumflex matches
+immediately after internal newlines as well as at the start of the subject
+string. It does not match after a newline that ends the string. A dollar
+matches before any newlines in the string, as well as at the very end, when
+PCRE_MULTILINE is set. When newline is specified as the two-character
+sequence CRLF, isolated CR and LF characters do not indicate newlines.
+

+

+For example, the pattern /^abc$/ matches the subject string "def\nabc" (where
+\n represents a newline) in multiline mode, but not otherwise. Consequently,
+patterns that are anchored in single line mode because all branches start with
+^ are not anchored in multiline mode, and a match for circumflex is possible
+when the startoffset argument of pcre_exec() is non-zero. The
+PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
+

+

+Note that the sequences \A, \Z, and \z can be used to match the start and
+end of the subject in both modes, and if all branches of a pattern start with
+\A it is always anchored, whether or not PCRE_MULTILINE is set.
+

+
FULL STOP (PERIOD, DOT) AND \N

+

+Outside a character class, a dot in the pattern matches any one character in
+the subject string except (by default) a character that signifies the end of a
+line.
+

+

+When a line ending is defined as a single character, dot never matches that
+character; when the two-character sequence CRLF is used, dot does not match CR
+if it is immediately followed by LF, but otherwise it matches all characters
+(including isolated CRs and LFs). When any Unicode line endings are being
+recognized, dot does not match CR or LF or any of the other line ending
+characters.
+

+

+The behaviour of dot with regard to newlines can be changed. If the PCRE_DOTALL
+option is set, a dot matches any one character, without exception. If the
+two-character sequence CRLF is present in the subject string, it takes two dots
+to match it.
+

+

+The handling of dot is entirely independent of the handling of circumflex and
+dollar, the only relationship being that they both involve newlines. Dot has no
+special meaning in a character class.
+

+

+The escape sequence \N behaves like a dot, except that it is not affected by
+the PCRE_DOTALL option. In other words, it matches any character except one
+that signifies the end of a line. Perl also uses \N to match characters by
+name; PCRE does not support this.
+

+
MATCHING A SINGLE DATA UNIT

+

+Outside a character class, the escape sequence \C matches any one data unit,
+whether or not a UTF mode is set. In the 8-bit library, one data unit is one
+byte; in the 16-bit library it is a 16-bit unit; in the 32-bit library it is
+a 32-bit unit. Unlike a dot, \C always
+matches line-ending characters. The feature is provided in Perl in order to
+match individual bytes in UTF-8 mode, but it is unclear how it can usefully be
+used. Because \C breaks up characters into individual data units, matching one
+unit with \C in a UTF mode means that the rest of the string may start with a
+malformed UTF character. This has undefined results, because PCRE assumes that
+it is dealing with valid UTF strings (and by default it checks this at the
+start of processing unless the PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK or
+PCRE_NO_UTF32_CHECK option is used).
+

+

+PCRE does not allow \C to appear in lookbehind assertions
+(described below)
+in a UTF mode, because this would make it impossible to calculate the length of
+the lookbehind.
+

+

+In general, the \C escape sequence is best avoided. However, one
+way of using it that avoids the problem of malformed UTF characters is to use a
+lookahead to check the length of the next character, as in this pattern, which
+could be used with a UTF-8 string (ignore white space and line breaks):
+
+  (?| (?=[\x00-\x7f])(\C) |
+      (?=[\x80-\x{7ff}])(\C)(\C) |
+      (?=[\x{800}-\x{ffff}])(\C)(\C)(\C) |
+      (?=[\x{10000}-\x{1fffff}])(\C)(\C)(\C)(\C))
+

+A group that starts with (?| resets the capturing parentheses numbers in each
+alternative (see
+"Duplicate Subpattern Numbers"
+below). The assertions at the start of each branch check the next UTF-8
+character for values whose encoding uses 1, 2, 3, or 4 bytes, respectively. The
+character's individual bytes are then captured by the appropriate number of
+groups.
+

+
SQUARE BRACKETS AND CHARACTER CLASSES

+

+An opening square bracket introduces a character class, terminated by a closing
+square bracket. A closing square bracket on its own is not special by default.
+However, if the PCRE_JAVASCRIPT_COMPAT option is set, a lone closing square
+bracket causes a compile-time error. If a closing square bracket is required as
+a member of the class, it should be the first data character in the class
+(after an initial circumflex, if present) or escaped with a backslash.
+

+

+A character class matches a single character in the subject. In a UTF mode, the
+character may be more than one data unit long. A matched character must be in
+the set of characters defined by the class, unless the first character in the
+class definition is a circumflex, in which case the subject character must not
+be in the set defined by the class. If a circumflex is actually required as a
+member of the class, ensure it is not the first character, or escape it with a
+backslash.
+

+

+For example, the character class [aeiou] matches any lower case vowel, while
+[^aeiou] matches any character that is not a lower case vowel. Note that a
+circumflex is just a convenient notation for specifying the characters that
+are in the class by enumerating those that are not. A class that starts with a
+circumflex is not an assertion; it still consumes a character from the subject
+string, and therefore it fails if the current pointer is at the end of the
+string.
+

+

+In UTF-8 (UTF-16, UTF-32) mode, characters with values greater than 255 (0xffff)
+can be included in a class as a literal string of data units, or by using the
+\x{ escaping mechanism.
+

+

+When caseless matching is set, any letters in a class represent both their
+upper case and lower case versions, so for example, a caseless [aeiou] matches
+"A" as well as "a", and a caseless [^aeiou] does not match "A", whereas a
+caseful version would. In a UTF mode, PCRE always understands the concept of
+case for characters whose values are less than 128, so caseless matching is
+always possible. For characters with higher values, the concept of case is
+supported if PCRE is compiled with Unicode property support, but not otherwise.
+If you want to use caseless matching in a UTF mode for characters 128 and
+above, you must ensure that PCRE is compiled with Unicode property support as
+well as with UTF support.
+

+

+Characters that might indicate line breaks are never treated in any special way
+when matching character classes, whatever line-ending sequence is in use, and
+whatever setting of the PCRE_DOTALL and PCRE_MULTILINE options is used. A class
+such as [^a] always matches one of these characters.
+

+

+The minus (hyphen) character can be used to specify a range of characters in a
+character class. For example, [d-m] matches any letter between d and m,
+inclusive. If a minus character is required in a class, it must be escaped with
+a backslash or appear in a position where it cannot be interpreted as
+indicating a range, typically as the first or last character in the class, or
+immediately after a range. For example, [b-d-z] matches letters in the range b
+to d, a hyphen character, or z.
+

+

+It is not possible to have the literal character "]" as the end character of a
+range. A pattern such as [W-]46] is interpreted as a class of two characters
+("W" and "-") followed by a literal string "46]", so it would match "W46]" or
+"-46]". However, if the "]" is escaped with a backslash it is interpreted as
+the end of range, so [W-\]46] is interpreted as a class containing a range
+followed by two other characters. The octal or hexadecimal representation of
+"]" can also be used to end a range.
+

+

+An error is generated if a POSIX character class (see below) or an escape
+sequence other than one that defines a single character appears at a point
+where a range ending character is expected. For example, [z-\xff] is valid,
+but [A-\d] and [A-[:digit:]] are not.
+

+

+Ranges operate in the collating sequence of character values. They can also be
+used for characters specified numerically, for example [\000-\037]. Ranges
+can include any characters that are valid for the current mode.
+

+

+If a range that includes letters is used when caseless matching is set, it
+matches the letters in either case. For example, [W-c] is equivalent to
+[][\\^_`wxyzabc], matched caselessly, and in a non-UTF mode, if character
+tables for a French locale are in use, [\xc8-\xcb] matches accented E
+characters in both cases. In UTF modes, PCRE supports the concept of case for
+characters with values greater than 128 only when it is compiled with Unicode
+property support.
+

+

+The character escape sequences \d, \D, \h, \H, \p, \P, \s, \S, \v,
+\V, \w, and \W may appear in a character class, and add the characters that
+they match to the class. For example, [\dABCDEF] matches any hexadecimal
+digit. In UTF modes, the PCRE_UCP option affects the meanings of \d, \s, \w
+and their upper case partners, just as it does when they appear outside a
+character class, as described in the section entitled
+"Generic character types"
+above. The escape sequence \b has a different meaning inside a character
+class; it matches the backspace character. The sequences \B, \N, \R, and \X
+are not special inside a character class. Like any other unrecognized escape
+sequences, they are treated as the literal characters "B", "N", "R", and "X" by
+default, but cause an error if the PCRE_EXTRA option is set.
+

+

+A circumflex can conveniently be used with the upper case character types to
+specify a more restricted set of characters than the matching lower case type.
+For example, the class [^\W_] matches any letter or digit, but not underscore,
+whereas [\w] includes underscore. A positive character class should be read as
+"something OR something OR ..." and a negative class as "NOT something AND NOT
+something AND NOT ...".
+

+

+The only metacharacters that are recognized in character classes are backslash,
+hyphen (only where it can be interpreted as specifying a range), circumflex
+(only at the start), opening square bracket (only when it can be interpreted as
+introducing a POSIX class name, or for a special compatibility feature - see
+the next two sections), and the terminating closing square bracket. However,
+escaping other non-alphanumeric characters does no harm.
+

+
POSIX CHARACTER CLASSES

+

+Perl supports the POSIX notation for character classes. This uses names
+enclosed by [: and :] within the enclosing square brackets. PCRE also supports
+this notation. For example,
+
+  [01[:alpha:]%]
+

+matches "0", "1", any alphabetic character, or "%". The supported class names
+are:
+
+  alnum    letters and digits
+  alpha    letters
+  ascii    character codes 0 - 127
+  blank    space or tab only
+  cntrl    control characters
+  digit    decimal digits (same as \d)
+  graph    printing characters, excluding space
+  lower    lower case letters
+  print    printing characters, including space
+  punct    printing characters, excluding letters and digits and space
+  space    white space (the same as \s from PCRE 8.34)
+  upper    upper case letters
+  word     "word" characters (same as \w)
+  xdigit   hexadecimal digits
+

+The default "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13),
+and space (32). If locale-specific matching is taking place, the list of space
+characters may be different; there may be fewer or more of them. "Space" used
+to be different to \s, which did not include VT, for Perl compatibility.
+However, Perl changed at release 5.18, and PCRE followed at release 8.34.
+"Space" and \s now match the same set of characters.
+

+

+The name "word" is a Perl extension, and "blank" is a GNU extension from Perl
+5.8. Another Perl extension is negation, which is indicated by a ^ character
+after the colon. For example,
+
+  [12[:^digit:]]
+

+matches "1", "2", or any non-digit. PCRE (and Perl) also recognize the POSIX
+syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not
+supported, and an error is given if they are encountered.
+

+

+By default, characters with values greater than 128 do not match any of the
+POSIX character classes. However, if the PCRE_UCP option is passed to
+pcre_compile(), some of the classes are changed so that Unicode character
+properties are used. This is achieved by replacing certain POSIX classes by
+other sequences, as follows:
+
+  [:alnum:]  becomes  \p{Xan}
+  [:alpha:]  becomes  \p{L}
+  [:blank:]  becomes  \h
+  [:digit:]  becomes  \p{Nd}
+  [:lower:]  becomes  \p{Ll}
+  [:space:]  becomes  \p{Xps}
+  [:upper:]  becomes  \p{Lu}
+  [:word:]   becomes  \p{Xwd}
+

+Negated versions, such as [:^alpha:] use \P instead of \p. Three other POSIX
+classes are handled specially in UCP mode:
+

+

+[:graph:]
+This matches characters that have glyphs that mark the page when printed. In
+Unicode property terms, it matches all characters with the L, M, N, P, S, or Cf
+properties, except for:
+
+  U+061C           Arabic Letter Mark
+  U+180E           Mongolian Vowel Separator
+  U+2066 - U+2069  Various "isolate"s
+
+

+

+

+[:print:]
+This matches the same characters as [:graph:] plus space characters that are
+not controls, that is, characters with the Zs property.
+

+

+[:punct:]
+This matches all characters that have the Unicode P (punctuation) property,
+plus those characters whose code points are less than 128 that have the S
+(Symbol) property.
+

+

+The other POSIX classes are unchanged, and match only characters with code
+points less than 128.
+

+
COMPATIBILITY FEATURE FOR WORD BOUNDARIES

+

+In the POSIX.2 compliant library that was included in 4.4BSD Unix, the ugly
+syntax [[:<:]] and [[:>:]] is used for matching "start of word" and "end of
+word". PCRE treats these items as follows:
+
+  [[:<:]]  is converted to  \b(?=\w)
+  [[:>:]]  is converted to  \b(?<=\w)
+

+Only these exact character sequences are recognized. A sequence such as
+[a[:<:]b] provokes error for an unrecognized POSIX class name. This support is
+not compatible with Perl. It is provided to help migrations from other
+environments, and is best not used in any new patterns. Note that \b matches
+at the start and the end of a word (see
+"Simple assertions"
+above), and in a Perl-style pattern the preceding or following character
+normally shows which is wanted, without the need for the assertions that are
+used above in order to give exactly the POSIX behaviour.
+

+
VERTICAL BAR

+

+Vertical bar characters are used to separate alternative patterns. For example,
+the pattern
+
+  gilbert|sullivan
+

+matches either "gilbert" or "sullivan". Any number of alternatives may appear,
+and an empty alternative is permitted (matching the empty string). The matching
+process tries each alternative in turn, from left to right, and the first one
+that succeeds is used. If the alternatives are within a subpattern
+(defined below),
+"succeeds" means matching the rest of the main pattern as well as the
+alternative in the subpattern.
+

+
INTERNAL OPTION SETTING

+

+The settings of the PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and
+PCRE_EXTENDED options (which are Perl-compatible) can be changed from within
+the pattern by a sequence of Perl option letters enclosed between "(?" and ")".
+The option letters are
+
+  i  for PCRE_CASELESS
+  m  for PCRE_MULTILINE
+  s  for PCRE_DOTALL
+  x  for PCRE_EXTENDED
+

+For example, (?im) sets caseless, multiline matching. It is also possible to
+unset these options by preceding the letter with a hyphen, and a combined
+setting and unsetting such as (?im-sx), which sets PCRE_CASELESS and
+PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, is also
+permitted. If a letter appears both before and after the hyphen, the option is
+unset.
+

+

+The PCRE-specific options PCRE_DUPNAMES, PCRE_UNGREEDY, and PCRE_EXTRA can be
+changed in the same way as the Perl-compatible options by using the characters
+J, U and X respectively.
+

+

+When one of these option changes occurs at top level (that is, not inside
+subpattern parentheses), the change applies to the remainder of the pattern
+that follows. If the change is placed right at the start of a pattern, PCRE
+extracts it into the global options (and it will therefore show up in data
+extracted by the pcre_fullinfo() function).
+

+

+An option change within a subpattern (see below for a description of
+subpatterns) affects only that part of the subpattern that follows it, so
+
+  (a(?i)b)c
+

+matches abc and aBc and no other strings (assuming PCRE_CASELESS is not used).
+By this means, options can be made to have different settings in different
+parts of the pattern. Any changes made in one alternative do carry on
+into subsequent branches within the same subpattern. For example,
+
+  (a(?i)b|c)
+

+matches "ab", "aB", "c", and "C", even though when matching "C" the first
+branch is abandoned before the option setting. This is because the effects of
+option settings happen at compile time. There would be some very weird
+behaviour otherwise.
+

+

+Note: There are other PCRE-specific options that can be set by the
+application when the compiling or matching functions are called. In some cases
+the pattern can contain special leading sequences such as (*CRLF) to override
+what the application has set or what has been defaulted. Details are given in
+the section entitled
+"Newline sequences"
+above. There are also the (*UTF8), (*UTF16),(*UTF32), and (*UCP) leading
+sequences that can be used to set UTF and Unicode property modes; they are
+equivalent to setting the PCRE_UTF8, PCRE_UTF16, PCRE_UTF32 and the PCRE_UCP
+options, respectively. The (*UTF) sequence is a generic version that can be
+used with any of the libraries. However, the application can set the
+PCRE_NEVER_UTF option, which locks out the use of the (*UTF) sequences.
+

+
SUBPATTERNS

+

+Subpatterns are delimited by parentheses (round brackets), which can be nested.
+Turning part of a pattern into a subpattern does two things:
+

+

+1. It localizes a set of alternatives. For example, the pattern
+
+  cat(aract|erpillar|)
+

+matches "cataract", "caterpillar", or "cat". Without the parentheses, it would
+match "cataract", "erpillar" or an empty string.
+

+

+2. It sets up the subpattern as a capturing subpattern. This means that, when
+the whole pattern matches, that portion of the subject string that matched the
+subpattern is passed back to the caller via the ovector argument of the
+matching function. (This applies only to the traditional matching functions;
+the DFA matching functions do not support capturing.)
+

+

+Opening parentheses are counted from left to right (starting from 1) to obtain
+numbers for the capturing subpatterns. For example, if the string "the red
+king" is matched against the pattern
+
+  the ((red|white) (king|queen))
+

+the captured substrings are "red king", "red", and "king", and are numbered 1,
+2, and 3, respectively.
+

+

+The fact that plain parentheses fulfil two functions is not always helpful.
+There are often times when a grouping subpattern is required without a
+capturing requirement. If an opening parenthesis is followed by a question mark
+and a colon, the subpattern does not do any capturing, and is not counted when
+computing the number of any subsequent capturing subpatterns. For example, if
+the string "the white queen" is matched against the pattern
+
+  the ((?:red|white) (king|queen))
+

+the captured substrings are "white queen" and "queen", and are numbered 1 and
+2. The maximum number of capturing subpatterns is 65535.
+

+

+As a convenient shorthand, if any option settings are required at the start of
+a non-capturing subpattern, the option letters may appear between the "?" and
+the ":". Thus the two patterns
+
+  (?i:saturday|sunday)
+  (?:(?i)saturday|sunday)
+

+match exactly the same set of strings. Because alternative branches are tried
+from left to right, and options are not reset until the end of the subpattern
+is reached, an option setting in one branch does affect subsequent branches, so
+the above patterns match "SUNDAY" as well as "Saturday".
+

+
DUPLICATE SUBPATTERN NUMBERS

+

+Perl 5.10 introduced a feature whereby each alternative in a subpattern uses
+the same numbers for its capturing parentheses. Such a subpattern starts with
+(?| and is itself a non-capturing subpattern. For example, consider this
+pattern:
+
+  (?|(Sat)ur|(Sun))day
+

+Because the two alternatives are inside a (?| group, both sets of capturing
+parentheses are numbered one. Thus, when the pattern matches, you can look
+at captured substring number one, whichever alternative matched. This construct
+is useful when you want to capture part, but not all, of one of a number of
+alternatives. Inside a (?| group, parentheses are numbered as usual, but the
+number is reset at the start of each branch. The numbers of any capturing
+parentheses that follow the subpattern start after the highest number used in
+any branch. The following example is taken from the Perl documentation. The
+numbers underneath show in which buffer the captured content will be stored.
+
+  # before  ---------------branch-reset----------- after
+  / ( a )  (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
+  # 1            2         2  3        2     3     4
+

+A back reference to a numbered subpattern uses the most recent value that is
+set for that number by any subpattern. The following pattern matches "abcabc"
+or "defdef":
+
+  /(?|(abc)|(def))\1/
+

+In contrast, a subroutine call to a numbered subpattern always refers to the
+first one in the pattern with the given number. The following pattern matches
+"abcabc" or "defabc":
+
+  /(?|(abc)|(def))(?1)/
+

+If a
+condition test
+for a subpattern's having matched refers to a non-unique number, the test is
+true if any of the subpatterns of that number have matched.
+

+

+An alternative approach to using this "branch reset" feature is to use
+duplicate named subpatterns, as described in the next section.
+

+
NAMED SUBPATTERNS

+

+Identifying capturing parentheses by number is simple, but it can be very hard
+to keep track of the numbers in complicated regular expressions. Furthermore,
+if an expression is modified, the numbers may change. To help with this
+difficulty, PCRE supports the naming of subpatterns. This feature was not
+added to Perl until release 5.10. Python had the feature earlier, and PCRE
+introduced it at release 4.0, using the Python syntax. PCRE now supports both
+the Perl and the Python syntax. Perl allows identically numbered subpatterns to
+have different names, but PCRE does not.
+

+

+In PCRE, a subpattern can be named in one of three ways: (?<name>...) or
+(?'name'...) as in Perl, or (?P<name>...) as in Python. References to capturing
+parentheses from other parts of the pattern, such as
+back references,
+recursion,
+and
+conditions,
+can be made by name as well as by number.
+

+

+Names consist of up to 32 alphanumeric characters and underscores, but must
+start with a non-digit. Named capturing parentheses are still allocated numbers
+as well as names, exactly as if the names were not present. The PCRE API
+provides function calls for extracting the name-to-number translation table
+from a compiled pattern. There is also a convenience function for extracting a
+captured substring by name.
+

+

+By default, a name must be unique within a pattern, but it is possible to relax
+this constraint by setting the PCRE_DUPNAMES option at compile time. (Duplicate
+names are also always permitted for subpatterns with the same number, set up as
+described in the previous section.) Duplicate names can be useful for patterns
+where only one instance of the named parentheses can match. Suppose you want to
+match the name of a weekday, either as a 3-letter abbreviation or as the full
+name, and in both cases you want to extract the abbreviation. This pattern
+(ignoring the line breaks) does the job:
+
+  (?<DN>Mon|Fri|Sun)(?:day)?|
+  (?<DN>Tue)(?:sday)?|
+  (?<DN>Wed)(?:nesday)?|
+  (?<DN>Thu)(?:rsday)?|
+  (?<DN>Sat)(?:urday)?
+

+There are five capturing substrings, but only one is ever set after a match.
+(An alternative way of solving this problem is to use a "branch reset"
+subpattern, as described in the previous section.)
+

+

+The convenience function for extracting the data by name returns the substring
+for the first (and in this example, the only) subpattern of that name that
+matched. This saves searching to find which numbered subpattern it was.
+

+

+If you make a back reference to a non-unique named subpattern from elsewhere in
+the pattern, the subpatterns to which the name refers are checked in the order
+in which they appear in the overall pattern. The first one that is set is used
+for the reference. For example, this pattern matches both "foofoo" and
+"barbar" but not "foobar" or "barfoo":
+
+  (?:(?<n>foo)|(?<n>bar))\k<n>
+
+

+

+

+If you make a subroutine call to a non-unique named subpattern, the one that
+corresponds to the first occurrence of the name is used. In the absence of
+duplicate numbers (see the previous section) this is the one with the lowest
+number.
+

+

+If you use a named reference in a condition
+test (see the
+section about conditions
+below), either to check whether a subpattern has matched, or to check for
+recursion, all subpatterns with the same name are tested. If the condition is
+true for any one of them, the overall condition is true. This is the same
+behaviour as testing by number. For further details of the interfaces for
+handling named subpatterns, see the
+pcreapi
+documentation.
+

+

+Warning: You cannot use different names to distinguish between two
+subpatterns with the same number because PCRE uses only the numbers when
+matching. For this reason, an error is given at compile time if different names
+are given to subpatterns with the same number. However, you can always give the
+same name to subpatterns with the same number, even when PCRE_DUPNAMES is not
+set.
+

+
REPETITION

+

+Repetition is specified by quantifiers, which can follow any of the following
+items:
+
+  a literal data character
+  the dot metacharacter
+  the \C escape sequence
+  the \X escape sequence
+  the \R escape sequence
+  an escape such as \d or \pL that matches a single character
+  a character class
+  a back reference (see next section)
+  a parenthesized subpattern (including assertions)
+  a subroutine call to a subpattern (recursive or otherwise)
+

+The general repetition quantifier specifies a minimum and maximum number of
+permitted matches, by giving the two numbers in curly brackets (braces),
+separated by a comma. The numbers must be less than 65536, and the first must
+be less than or equal to the second. For example:
+
+  z{2,4}
+

+matches "zz", "zzz", or "zzzz". A closing brace on its own is not a special
+character. If the second number is omitted, but the comma is present, there is
+no upper limit; if the second number and the comma are both omitted, the
+quantifier specifies an exact number of required matches. Thus
+
+  [aeiou]{3,}
+

+matches at least 3 successive vowels, but may match many more, while
+
+  \d{8}
+

+matches exactly 8 digits. An opening curly bracket that appears in a position
+where a quantifier is not allowed, or one that does not match the syntax of a
+quantifier, is taken as a literal character. For example, {,6} is not a
+quantifier, but a literal string of four characters.
+

+

+In UTF modes, quantifiers apply to characters rather than to individual data
+units. Thus, for example, \x{100}{2} matches two characters, each of
+which is represented by a two-byte sequence in a UTF-8 string. Similarly,
+\X{3} matches three Unicode extended grapheme clusters, each of which may be
+several data units long (and they may be of different lengths).
+

+

+The quantifier {0} is permitted, causing the expression to behave as if the
+previous item and the quantifier were not present. This may be useful for
+subpatterns that are referenced as
+subroutines
+from elsewhere in the pattern (but see also the section entitled
+"Defining subpatterns for use by reference only"
+below). Items other than subpatterns that have a {0} quantifier are omitted
+from the compiled pattern.
+

+

+For convenience, the three most common quantifiers have single-character
+abbreviations:
+
+  *    is equivalent to {0,}
+  +    is equivalent to {1,}
+  ?    is equivalent to {0,1}
+

+It is possible to construct infinite loops by following a subpattern that can
+match no characters with a quantifier that has no upper limit, for example:
+
+  (a?)*
+

+Earlier versions of Perl and PCRE used to give an error at compile time for
+such patterns. However, because there are cases where this can be useful, such
+patterns are now accepted, but if any repetition of the subpattern does in fact
+match no characters, the loop is forcibly broken.
+

+

+By default, the quantifiers are "greedy", that is, they match as much as
+possible (up to the maximum number of permitted times), without causing the
+rest of the pattern to fail. The classic example of where this gives problems
+is in trying to match comments in C programs. These appear between /* and */
+and within the comment, individual * and / characters may appear. An attempt to
+match C comments by applying the pattern
+
+  /\*.*\*/
+

+to the string
+
+  /* first comment */  not comment  /* second comment */
+

+fails, because it matches the entire string owing to the greediness of the .*
+item.
+

+

+However, if a quantifier is followed by a question mark, it ceases to be
+greedy, and instead matches the minimum number of times possible, so the
+pattern
+
+  /\*.*?\*/
+

+does the right thing with the C comments. The meaning of the various
+quantifiers is not otherwise changed, just the preferred number of matches.
+Do not confuse this use of question mark with its use as a quantifier in its
+own right. Because it has two uses, it can sometimes appear doubled, as in
+
+  \d??\d
+

+which matches one digit by preference, but can match two if that is the only
+way the rest of the pattern matches.
+

+

+If the PCRE_UNGREEDY option is set (an option that is not available in Perl),
+the quantifiers are not greedy by default, but individual ones can be made
+greedy by following them with a question mark. In other words, it inverts the
+default behaviour.
+

+

+When a parenthesized subpattern is quantified with a minimum repeat count that
+is greater than 1 or with a limited maximum, more memory is required for the
+compiled pattern, in proportion to the size of the minimum or maximum.
+

+

+If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equivalent
+to Perl's /s) is set, thus allowing the dot to match newlines, the pattern is
+implicitly anchored, because whatever follows will be tried against every
+character position in the subject string, so there is no point in retrying the
+overall match at any position after the first. PCRE normally treats such a
+pattern as though it were preceded by \A.
+

+

+In cases where it is known that the subject string contains no newlines, it is
+worth setting PCRE_DOTALL in order to obtain this optimization, or
+alternatively using ^ to indicate anchoring explicitly.
+

+

+However, there are some cases where the optimization cannot be used. When .*
+is inside capturing parentheses that are the subject of a back reference
+elsewhere in the pattern, a match at the start may fail where a later one
+succeeds. Consider, for example:
+
+  (.*)abc\1
+

+If the subject is "xyz123abc123" the match point is the fourth character. For
+this reason, such a pattern is not implicitly anchored.
+

+

+Another case where implicit anchoring is not applied is when the leading .* is
+inside an atomic group. Once again, a match at the start may fail where a later
+one succeeds. Consider this pattern:
+
+  (?>.*?a)b
+

+It matches "ab" in the subject "aab". The use of the backtracking control verbs
+(*PRUNE) and (*SKIP) also disable this optimization.
+

+

+When a capturing subpattern is repeated, the value captured is the substring
+that matched the final iteration. For example, after
+
+  (tweedle[dume]{3}\s*)+
+

+has matched "tweedledum tweedledee" the value of the captured substring is
+"tweedledee". However, if there are nested capturing subpatterns, the
+corresponding captured values may have been set in previous iterations. For
+example, after
+
+  /(a|(b))+/
+

+matches "aba" the value of the second captured substring is "b".
+

+
ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS

+

+With both maximizing ("greedy") and minimizing ("ungreedy" or "lazy")
+repetition, failure of what follows normally causes the repeated item to be
+re-evaluated to see if a different number of repeats allows the rest of the
+pattern to match. Sometimes it is useful to prevent this, either to change the
+nature of the match, or to cause it fail earlier than it otherwise might, when
+the author of the pattern knows there is no point in carrying on.
+

+

+Consider, for example, the pattern \d+foo when applied to the subject line
+
+  123456bar
+

+After matching all 6 digits and then failing to match "foo", the normal
+action of the matcher is to try again with only 5 digits matching the \d+
+item, and then with 4, and so on, before ultimately failing. "Atomic grouping"
+(a term taken from Jeffrey Friedl's book) provides the means for specifying
+that once a subpattern has matched, it is not to be re-evaluated in this way.
+

+

+If we use atomic grouping for the previous example, the matcher gives up
+immediately on failing to match "foo" the first time. The notation is a kind of
+special parenthesis, starting with (?> as in this example:
+
+  (?>\d+)foo
+

+This kind of parenthesis "locks up" the  part of the pattern it contains once
+it has matched, and a failure further into the pattern is prevented from
+backtracking into it. Backtracking past it to previous items, however, works as
+normal.
+

+

+An alternative description is that a subpattern of this type matches the string
+of characters that an identical standalone pattern would match, if anchored at
+the current point in the subject string.
+

+

+Atomic grouping subpatterns are not capturing subpatterns. Simple cases such as
+the above example can be thought of as a maximizing repeat that must swallow
+everything it can. So, while both \d+ and \d+? are prepared to adjust the
+number of digits they match in order to make the rest of the pattern match,
+(?>\d+) can only match an entire sequence of digits.
+

+

+Atomic groups in general can of course contain arbitrarily complicated
+subpatterns, and can be nested. However, when the subpattern for an atomic
+group is just a single repeated item, as in the example above, a simpler
+notation, called a "possessive quantifier" can be used. This consists of an
+additional + character following a quantifier. Using this notation, the
+previous example can be rewritten as
+
+  \d++foo
+

+Note that a possessive quantifier can be used with an entire group, for
+example:
+
+  (abc|xyz){2,3}+
+

+Possessive quantifiers are always greedy; the setting of the PCRE_UNGREEDY
+option is ignored. They are a convenient notation for the simpler forms of
+atomic group. However, there is no difference in the meaning of a possessive
+quantifier and the equivalent atomic group, though there may be a performance
+difference; possessive quantifiers should be slightly faster.
+

+

+The possessive quantifier syntax is an extension to the Perl 5.8 syntax.
+Jeffrey Friedl originated the idea (and the name) in the first edition of his
+book. Mike McCloskey liked it, so implemented it when he built Sun's Java
+package, and PCRE copied it from there. It ultimately found its way into Perl
+at release 5.10.
+

+

+PCRE has an optimization that automatically "possessifies" certain simple
+pattern constructs. For example, the sequence A+B is treated as A++B because
+there is no point in backtracking into a sequence of A's when B must follow.
+

+

+When a pattern contains an unlimited repeat inside a subpattern that can itself
+be repeated an unlimited number of times, the use of an atomic group is the
+only way to avoid some failing matches taking a very long time indeed. The
+pattern
+
+  (\D+|<\d+>)*[!?]
+

+matches an unlimited number of substrings that either consist of non-digits, or
+digits enclosed in <>, followed by either ! or ?. When it matches, it runs
+quickly. However, if it is applied to
+
+  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+

+it takes a long time before reporting failure. This is because the string can
+be divided between the internal \D+ repeat and the external * repeat in a
+large number of ways, and all have to be tried. (The example uses [!?] rather
+than a single character at the end, because both PCRE and Perl have an
+optimization that allows for fast failure when a single character is used. They
+remember the last single character that is required for a match, and fail early
+if it is not present in the string.) If the pattern is changed so that it uses
+an atomic group, like this:
+
+  ((?>\D+)|<\d+>)*[!?]
+

+sequences of non-digits cannot be broken, and failure happens quickly.
+

+
BACK REFERENCES

+

+Outside a character class, a backslash followed by a digit greater than 0 (and
+possibly further digits) is a back reference to a capturing subpattern earlier
+(that is, to its left) in the pattern, provided there have been that many
+previous capturing left parentheses.
+

+

+However, if the decimal number following the backslash is less than 10, it is
+always taken as a back reference, and causes an error only if there are not
+that many capturing left parentheses in the entire pattern. In other words, the
+parentheses that are referenced need not be to the left of the reference for
+numbers less than 10. A "forward back reference" of this type can make sense
+when a repetition is involved and the subpattern to the right has participated
+in an earlier iteration.
+

+

+It is not possible to have a numerical "forward back reference" to a subpattern
+whose number is 10 or more using this syntax because a sequence such as \50 is
+interpreted as a character defined in octal. See the subsection entitled
+"Non-printing characters"
+above
+for further details of the handling of digits following a backslash. There is
+no such problem when named parentheses are used. A back reference to any
+subpattern is possible using named parentheses (see below).
+

+

+Another way of avoiding the ambiguity inherent in the use of digits following a
+backslash is to use the \g escape sequence. This escape must be followed by an
+unsigned number or a negative number, optionally enclosed in braces. These
+examples are all identical:
+
+  (ring), \1
+  (ring), \g1
+  (ring), \g{1}
+

+An unsigned number specifies an absolute reference without the ambiguity that
+is present in the older syntax. It is also useful when literal digits follow
+the reference. A negative number is a relative reference. Consider this
+example:
+
+  (abc(def)ghi)\g{-1}
+

+The sequence \g{-1} is a reference to the most recently started capturing
+subpattern before \g, that is, is it equivalent to \2 in this example.
+Similarly, \g{-2} would be equivalent to \1. The use of relative references
+can be helpful in long patterns, and also in patterns that are created by
+joining together fragments that contain references within themselves.
+

+

+A back reference matches whatever actually matched the capturing subpattern in
+the current subject string, rather than anything matching the subpattern
+itself (see
+"Subpatterns as subroutines"
+below for a way of doing that). So the pattern
+
+  (sens|respons)e and \1ibility
+

+matches "sense and sensibility" and "response and responsibility", but not
+"sense and responsibility". If caseful matching is in force at the time of the
+back reference, the case of letters is relevant. For example,
+
+  ((?i)rah)\s+\1
+

+matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original
+capturing subpattern is matched caselessly.
+

+

+There are several different ways of writing back references to named
+subpatterns. The .NET syntax \k{name} and the Perl syntax \k<name> or
+\k'name' are supported, as is the Python syntax (?P=name). Perl 5.10's unified
+back reference syntax, in which \g can be used for both numeric and named
+references, is also supported. We could rewrite the above example in any of
+the following ways:
+
+  (?<p1>(?i)rah)\s+\k<p1>
+  (?'p1'(?i)rah)\s+\k{p1}
+  (?P<p1>(?i)rah)\s+(?P=p1)
+  (?<p1>(?i)rah)\s+\g{p1}
+

+A subpattern that is referenced by name may appear in the pattern before or
+after the reference.
+

+

+There may be more than one back reference to the same subpattern. If a
+subpattern has not actually been used in a particular match, any back
+references to it always fail by default. For example, the pattern
+
+  (a|(bc))\2
+

+always fails if it starts to match "a" rather than "bc". However, if the
+PCRE_JAVASCRIPT_COMPAT option is set at compile time, a back reference to an
+unset value matches an empty string.
+

+

+Because there may be many capturing parentheses in a pattern, all digits
+following a backslash are taken as part of a potential back reference number.
+If the pattern continues with a digit character, some delimiter must be used to
+terminate the back reference. If the PCRE_EXTENDED option is set, this can be
+white space. Otherwise, the \g{ syntax or an empty comment (see
+"Comments"
+below) can be used.
+

+

+Recursive back references
+

+

+A back reference that occurs inside the parentheses to which it refers fails
+when the subpattern is first used, so, for example, (a\1) never matches.
+However, such references can be useful inside repeated subpatterns. For
+example, the pattern
+
+  (a|b\1)+
+

+matches any number of "a"s and also "aba", "ababbaa" etc. At each iteration of
+the subpattern, the back reference matches the character string corresponding
+to the previous iteration. In order for this to work, the pattern must be such
+that the first iteration does not need to match the back reference. This can be
+done using alternation, as in the example above, or by a quantifier with a
+minimum of zero.
+

+

+Back references of this type cause the group that they reference to be treated
+as an
+atomic group.
+Once the whole group has been matched, a subsequent matching failure cannot
+cause backtracking into the middle of the group.
+

+
ASSERTIONS

+

+An assertion is a test on the characters following or preceding the current
+matching point that does not actually consume any characters. The simple
+assertions coded as \b, \B, \A, \G, \Z, \z, ^ and $ are described
+above.
+

+

+More complicated assertions are coded as subpatterns. There are two kinds:
+those that look ahead of the current position in the subject string, and those
+that look behind it. An assertion subpattern is matched in the normal way,
+except that it does not cause the current matching position to be changed.
+

+

+Assertion subpatterns are not capturing subpatterns. If such an assertion
+contains capturing subpatterns within it, these are counted for the purposes of
+numbering the capturing subpatterns in the whole pattern. However, substring
+capturing is carried out only for positive assertions. (Perl sometimes, but not
+always, does do capturing in negative assertions.)
+

+

+For compatibility with Perl, assertion subpatterns may be repeated; though
+it makes no sense to assert the same thing several times, the side effect of
+capturing parentheses may occasionally be useful. In practice, there only three
+cases:
+

+

+(1) If the quantifier is {0}, the assertion is never obeyed during matching.
+However, it may contain internal capturing parenthesized groups that are called
+from elsewhere via the
+subroutine mechanism.
+

+

+(2) If quantifier is {0,n} where n is greater than zero, it is treated as if it
+were {0,1}. At run time, the rest of the pattern match is tried with and
+without the assertion, the order depending on the greediness of the quantifier.
+

+

+(3) If the minimum repetition is greater than zero, the quantifier is ignored.
+The assertion is obeyed just once when encountered during matching.
+

+

+Lookahead assertions
+

+

+Lookahead assertions start with (?= for positive assertions and (?! for
+negative assertions. For example,
+
+  \w+(?=;)
+

+matches a word followed by a semicolon, but does not include the semicolon in
+the match, and
+
+  foo(?!bar)
+

+matches any occurrence of "foo" that is not followed by "bar". Note that the
+apparently similar pattern
+
+  (?!foo)bar
+

+does not find an occurrence of "bar" that is preceded by something other than
+"foo"; it finds any occurrence of "bar" whatsoever, because the assertion
+(?!foo) is always true when the next three characters are "bar". A
+lookbehind assertion is needed to achieve the other effect.
+

+

+If you want to force a matching failure at some point in a pattern, the most
+convenient way to do it is with (?!) because an empty string always matches, so
+an assertion that requires there not to be an empty string must always fail.
+The backtracking control verb (*FAIL) or (*F) is a synonym for (?!).
+

+

+Lookbehind assertions
+

+

+Lookbehind assertions start with (?<= for positive assertions and (?<! for
+negative assertions. For example,
+
+  (?<!foo)bar
+

+does find an occurrence of "bar" that is not preceded by "foo". The contents of
+a lookbehind assertion are restricted such that all the strings it matches must
+have a fixed length. However, if there are several top-level alternatives, they
+do not all have to have the same fixed length. Thus
+
+  (?<=bullock|donkey)
+

+is permitted, but
+
+  (?<!dogs?|cats?)
+

+causes an error at compile time. Branches that match different length strings
+are permitted only at the top level of a lookbehind assertion. This is an
+extension compared with Perl, which requires all branches to match the same
+length of string. An assertion such as
+
+  (?<=ab(c|de))
+

+is not permitted, because its single top-level branch can match two different
+lengths, but it is acceptable to PCRE if rewritten to use two top-level
+branches:
+
+  (?<=abc|abde)
+

+In some cases, the escape sequence \K
+(see above)
+can be used instead of a lookbehind assertion to get round the fixed-length
+restriction.
+

+

+The implementation of lookbehind assertions is, for each alternative, to
+temporarily move the current position back by the fixed length and then try to
+match. If there are insufficient characters before the current position, the
+assertion fails.
+

+

+In a UTF mode, PCRE does not allow the \C escape (which matches a single data
+unit even in a UTF mode) to appear in lookbehind assertions, because it makes
+it impossible to calculate the length of the lookbehind. The \X and \R
+escapes, which can match different numbers of data units, are also not
+permitted.
+

+

+"Subroutine"
+calls (see below) such as (?2) or (?&X) are permitted in lookbehinds, as long
+as the subpattern matches a fixed-length string.
+Recursion,
+however, is not supported.
+

+

+Possessive quantifiers can be used in conjunction with lookbehind assertions to
+specify efficient matching of fixed-length strings at the end of subject
+strings. Consider a simple pattern such as
+
+  abcd$
+

+when applied to a long string that does not match. Because matching proceeds
+from left to right, PCRE will look for each "a" in the subject and then see if
+what follows matches the rest of the pattern. If the pattern is specified as
+
+  ^.*abcd$
+

+the initial .* matches the entire string at first, but when this fails (because
+there is no following "a"), it backtracks to match all but the last character,
+then all but the last two characters, and so on. Once again the search for "a"
+covers the entire string, from right to left, so we are no better off. However,
+if the pattern is written as
+
+  ^.*+(?<=abcd)
+

+there can be no backtracking for the .*+ item; it can match only the entire
+string. The subsequent lookbehind assertion does a single test on the last four
+characters. If it fails, the match fails immediately. For long strings, this
+approach makes a significant difference to the processing time.
+

+

+Using multiple assertions
+

+

+Several assertions (of any sort) may occur in succession. For example,
+
+  (?<=\d{3})(?<!999)foo
+

+matches "foo" preceded by three digits that are not "999". Notice that each of
+the assertions is applied independently at the same point in the subject
+string. First there is a check that the previous three characters are all
+digits, and then there is a check that the same three characters are not "999".
+This pattern does not match "foo" preceded by six characters, the first
+of which are digits and the last three of which are not "999". For example, it
+doesn't match "123abcfoo". A pattern to do that is
+
+  (?<=\d{3}...)(?<!999)foo
+

+This time the first assertion looks at the preceding six characters, checking
+that the first three are digits, and then the second assertion checks that the
+preceding three characters are not "999".
+

+

+Assertions can be nested in any combination. For example,
+
+  (?<=(?<!foo)bar)baz
+

+matches an occurrence of "baz" that is preceded by "bar" which in turn is not
+preceded by "foo", while
+
+  (?<=\d{3}(?!999)...)foo
+

+is another pattern that matches "foo" preceded by three digits and any three
+characters that are not "999".
+

+
CONDITIONAL SUBPATTERNS

+

+It is possible to cause the matching process to obey a subpattern
+conditionally or to choose between two alternative subpatterns, depending on
+the result of an assertion, or whether a specific capturing subpattern has
+already been matched. The two possible forms of conditional subpattern are:
+
+  (?(condition)yes-pattern)
+  (?(condition)yes-pattern|no-pattern)
+

+If the condition is satisfied, the yes-pattern is used; otherwise the
+no-pattern (if present) is used. If there are more than two alternatives in the
+subpattern, a compile-time error occurs. Each of the two alternatives may
+itself contain nested subpatterns of any form, including conditional
+subpatterns; the restriction to two alternatives applies only at the level of
+the condition. This pattern fragment is an example where the alternatives are
+complex:
+
+  (?(1) (A|B|C) | (D | (?(2)E|F) | E) )
+
+

+

+

+There are four kinds of condition: references to subpatterns, references to
+recursion, a pseudo-condition called DEFINE, and assertions.
+

+

+Checking for a used subpattern by number
+

+

+If the text between the parentheses consists of a sequence of digits, the
+condition is true if a capturing subpattern of that number has previously
+matched. If there is more than one capturing subpattern with the same number
+(see the earlier
+section about duplicate subpattern numbers),
+the condition is true if any of them have matched. An alternative notation is
+to precede the digits with a plus or minus sign. In this case, the subpattern
+number is relative rather than absolute. The most recently opened parentheses
+can be referenced by (?(-1), the next most recent by (?(-2), and so on. Inside
+loops it can also make sense to refer to subsequent groups. The next
+parentheses to be opened can be referenced as (?(+1), and so on. (The value
+zero in any of these forms is not used; it provokes a compile-time error.)
+

+

+Consider the following pattern, which contains non-significant white space to
+make it more readable (assume the PCRE_EXTENDED option) and to divide it into
+three parts for ease of discussion:
+
+  ( \( )?    [^()]+    (?(1) \) )
+

+The first part matches an optional opening parenthesis, and if that
+character is present, sets it as the first captured substring. The second part
+matches one or more characters that are not parentheses. The third part is a
+conditional subpattern that tests whether or not the first set of parentheses
+matched. If they did, that is, if subject started with an opening parenthesis,
+the condition is true, and so the yes-pattern is executed and a closing
+parenthesis is required. Otherwise, since no-pattern is not present, the
+subpattern matches nothing. In other words, this pattern matches a sequence of
+non-parentheses, optionally enclosed in parentheses.
+

+

+If you were embedding this pattern in a larger one, you could use a relative
+reference:
+
+  ...other stuff... ( \( )?    [^()]+    (?(-1) \) ) ...
+

+This makes the fragment independent of the parentheses in the larger pattern.
+

+

+Checking for a used subpattern by name
+

+

+Perl uses the syntax (?(<name>)...) or (?('name')...) to test for a used
+subpattern by name. For compatibility with earlier versions of PCRE, which had
+this facility before Perl, the syntax (?(name)...) is also recognized.
+

+

+Rewriting the above example to use a named subpattern gives this:
+
+  (?<OPEN> \( )?    [^()]+    (?(<OPEN>) \) )
+

+If the name used in a condition of this kind is a duplicate, the test is
+applied to all subpatterns of the same name, and is true if any one of them has
+matched.
+

+

+Checking for pattern recursion
+

+

+If the condition is the string (R), and there is no subpattern with the name R,
+the condition is true if a recursive call to the whole pattern or any
+subpattern has been made. If digits or a name preceded by ampersand follow the
+letter R, for example:
+
+  (?(R3)...) or (?(R&name)...)
+

+the condition is true if the most recent recursion is into a subpattern whose
+number or name is given. This condition does not check the entire recursion
+stack. If the name used in a condition of this kind is a duplicate, the test is
+applied to all subpatterns of the same name, and is true if any one of them is
+the most recent recursion.
+

+

+At "top level", all these recursion test conditions are false.
+The syntax for recursive patterns
+is described below.
+

+

+Defining subpatterns for use by reference only
+

+

+If the condition is the string (DEFINE), and there is no subpattern with the
+name DEFINE, the condition is always false. In this case, there may be only one
+alternative in the subpattern. It is always skipped if control reaches this
+point in the pattern; the idea of DEFINE is that it can be used to define
+subroutines that can be referenced from elsewhere. (The use of
+subroutines
+is described below.) For example, a pattern to match an IPv4 address such as
+"192.168.23.245" could be written like this (ignore white space and line
+breaks):
+
+  (?(DEFINE) (?<byte> 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) )
+  \b (?&byte) (\.(?&byte)){3} \b
+

+The first part of the pattern is a DEFINE group inside which a another group
+named "byte" is defined. This matches an individual component of an IPv4
+address (a number less than 256). When matching takes place, this part of the
+pattern is skipped because DEFINE acts like a false condition. The rest of the
+pattern uses references to the named group to match the four dot-separated
+components of an IPv4 address, insisting on a word boundary at each end.
+

+

+Assertion conditions
+

+

+If the condition is not in any of the above formats, it must be an assertion.
+This may be a positive or negative lookahead or lookbehind assertion. Consider
+this pattern, again containing non-significant white space, and with the two
+alternatives on the second line:
+
+  (?(?=[^a-z]*[a-z])
+  \d{2}-[a-z]{3}-\d{2}  |  \d{2}-\d{2}-\d{2} )
+

+The condition is a positive lookahead assertion that matches an optional
+sequence of non-letters followed by a letter. In other words, it tests for the
+presence of at least one letter in the subject. If a letter is found, the
+subject is matched against the first alternative; otherwise it is matched
+against the second. This pattern matches strings in one of the two forms
+dd-aaa-dd or dd-dd-dd, where aaa are letters and dd are digits.
+

+
COMMENTS

+

+There are two ways of including comments in patterns that are processed by
+PCRE. In both cases, the start of the comment must not be in a character class,
+nor in the middle of any other sequence of related characters such as (?: or a
+subpattern name or number. The characters that make up a comment play no part
+in the pattern matching.
+

+

+The sequence (?# marks the start of a comment that continues up to the next
+closing parenthesis. Nested parentheses are not permitted. If the PCRE_EXTENDED
+option is set, an unescaped # character also introduces a comment, which in
+this case continues to immediately after the next newline character or
+character sequence in the pattern. Which characters are interpreted as newlines
+is controlled by the options passed to a compiling function or by a special
+sequence at the start of the pattern, as described in the section entitled
+"Newline conventions"
+above. Note that the end of this type of comment is a literal newline sequence
+in the pattern; escape sequences that happen to represent a newline do not
+count. For example, consider this pattern when PCRE_EXTENDED is set, and the
+default newline convention is in force:
+
+  abc #comment \n still comment
+

+On encountering the # character, pcre_compile() skips along, looking for
+a newline in the pattern. The sequence \n is still literal at this stage, so
+it does not terminate the comment. Only an actual character with the code value
+0x0a (the default newline) does so.
+

+
RECURSIVE PATTERNS

+

+Consider the problem of matching a string in parentheses, allowing for
+unlimited nested parentheses. Without the use of recursion, the best that can
+be done is to use a pattern that matches up to some fixed depth of nesting. It
+is not possible to handle an arbitrary nesting depth.
+

+

+For some time, Perl has provided a facility that allows regular expressions to
+recurse (amongst other things). It does this by interpolating Perl code in the
+expression at run time, and the code can refer to the expression itself. A Perl
+pattern using code interpolation to solve the parentheses problem can be
+created like this:
+
+  $re = qr{\( (?: (?>[^()]+) | (?p{$re}) )* \)}x;
+

+The (?p{...}) item interpolates Perl code at run time, and in this case refers
+recursively to the pattern in which it appears.
+

+

+Obviously, PCRE cannot support the interpolation of Perl code. Instead, it
+supports special syntax for recursion of the entire pattern, and also for
+individual subpattern recursion. After its introduction in PCRE and Python,
+this kind of recursion was subsequently introduced into Perl at release 5.10.
+

+

+A special item that consists of (? followed by a number greater than zero and a
+closing parenthesis is a recursive subroutine call of the subpattern of the
+given number, provided that it occurs inside that subpattern. (If not, it is a
+non-recursive subroutine
+call, which is described in the next section.) The special item (?R) or (?0) is
+a recursive call of the entire regular expression.
+

+

+This PCRE pattern solves the nested parentheses problem (assume the
+PCRE_EXTENDED option is set so that white space is ignored):
+
+  \( ( [^()]++ | (?R) )* \)
+

+First it matches an opening parenthesis. Then it matches any number of
+substrings which can either be a sequence of non-parentheses, or a recursive
+match of the pattern itself (that is, a correctly parenthesized substring).
+Finally there is a closing parenthesis. Note the use of a possessive quantifier
+to avoid backtracking into sequences of non-parentheses.
+

+

+If this were part of a larger pattern, you would not want to recurse the entire
+pattern, so instead you could use this:
+
+  ( \( ( [^()]++ | (?1) )* \) )
+

+We have put the pattern into parentheses, and caused the recursion to refer to
+them instead of the whole pattern.
+

+

+In a larger pattern, keeping track of parenthesis numbers can be tricky. This
+is made easier by the use of relative references. Instead of (?1) in the
+pattern above you can write (?-2) to refer to the second most recently opened
+parentheses preceding the recursion. In other words, a negative number counts
+capturing parentheses leftwards from the point at which it is encountered.
+

+

+It is also possible to refer to subsequently opened parentheses, by writing
+references such as (?+2). However, these cannot be recursive because the
+reference is not inside the parentheses that are referenced. They are always
+non-recursive subroutine
+calls, as described in the next section.
+

+

+An alternative approach is to use named parentheses instead. The Perl syntax
+for this is (?&name); PCRE's earlier syntax (?P>name) is also supported. We
+could rewrite the above example as follows:
+
+  (?<pn> \( ( [^()]++ | (?&pn) )* \) )
+

+If there is more than one subpattern with the same name, the earliest one is
+used.
+

+

+This particular example pattern that we have been looking at contains nested
+unlimited repeats, and so the use of a possessive quantifier for matching
+strings of non-parentheses is important when applying the pattern to strings
+that do not match. For example, when this pattern is applied to
+
+  (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
+

+it yields "no match" quickly. However, if a possessive quantifier is not used,
+the match runs for a very long time indeed because there are so many different
+ways the + and * repeats can carve up the subject, and all have to be tested
+before failure can be reported.
+

+

+At the end of a match, the values of capturing parentheses are those from
+the outermost level. If you want to obtain intermediate values, a callout
+function can be used (see below and the
+pcrecallout
+documentation). If the pattern above is matched against
+
+  (ab(cd)ef)
+

+the value for the inner capturing parentheses (numbered 2) is "ef", which is
+the last value taken on at the top level. If a capturing subpattern is not
+matched at the top level, its final captured value is unset, even if it was
+(temporarily) set at a deeper level during the matching process.
+

+

+If there are more than 15 capturing parentheses in a pattern, PCRE has to
+obtain extra memory to store data during a recursion, which it does by using
+pcre_malloc, freeing it via pcre_free afterwards. If no memory can
+be obtained, the match fails with the PCRE_ERROR_NOMEMORY error.
+

+

+Do not confuse the (?R) item with the condition (R), which tests for recursion.
+Consider this pattern, which matches text in angle brackets, allowing for
+arbitrary nesting. Only digits are allowed in nested brackets (that is, when
+recursing), whereas any characters are permitted at the outer level.
+
+  < (?: (?(R) \d++  | [^<>]*+) | (?R)) * >
+

+In this pattern, (?(R) is the start of a conditional subpattern, with two
+different alternatives for the recursive and non-recursive cases. The (?R) item
+is the actual recursive call.
+

+

+Differences in recursion processing between PCRE and Perl
+

+

+Recursion processing in PCRE differs from Perl in two important ways. In PCRE
+(like Python, but unlike Perl), a recursive subpattern call is always treated
+as an atomic group. That is, once it has matched some of the subject string, it
+is never re-entered, even if it contains untried alternatives and there is a
+subsequent matching failure. This can be illustrated by the following pattern,
+which purports to match a palindromic string that contains an odd number of
+characters (for example, "a", "aba", "abcba", "abcdcba"):
+
+  ^(.|(.)(?1)\2)$
+

+The idea is that it either matches a single character, or two identical
+characters surrounding a sub-palindrome. In Perl, this pattern works; in PCRE
+it does not if the pattern is longer than three characters. Consider the
+subject string "abcba":
+

+

+At the top level, the first character is matched, but as it is not at the end
+of the string, the first alternative fails; the second alternative is taken
+and the recursion kicks in. The recursive call to subpattern 1 successfully
+matches the next character ("b"). (Note that the beginning and end of line
+tests are not part of the recursion).
+

+

+Back at the top level, the next character ("c") is compared with what
+subpattern 2 matched, which was "a". This fails. Because the recursion is
+treated as an atomic group, there are now no backtracking points, and so the
+entire match fails. (Perl is able, at this point, to re-enter the recursion and
+try the second alternative.) However, if the pattern is written with the
+alternatives in the other order, things are different:
+
+  ^((.)(?1)\2|.)$
+

+This time, the recursing alternative is tried first, and continues to recurse
+until it runs out of characters, at which point the recursion fails. But this
+time we do have another alternative to try at the higher level. That is the big
+difference: in the previous case the remaining alternative is at a deeper
+recursion level, which PCRE cannot use.
+

+

+To change the pattern so that it matches all palindromic strings, not just
+those with an odd number of characters, it is tempting to change the pattern to
+this:
+
+  ^((.)(?1)\2|.?)$
+

+Again, this works in Perl, but not in PCRE, and for the same reason. When a
+deeper recursion has matched a single character, it cannot be entered again in
+order to match an empty string. The solution is to separate the two cases, and
+write out the odd and even cases as alternatives at the higher level:
+
+  ^(?:((.)(?1)\2|)|((.)(?3)\4|.))
+

+If you want to match typical palindromic phrases, the pattern has to ignore all
+non-word characters, which can be done like this:
+
+  ^\W*+(?:((.)\W*+(?1)\W*+\2|)|((.)\W*+(?3)\W*+\4|\W*+.\W*+))\W*+$
+

+If run with the PCRE_CASELESS option, this pattern matches phrases such as "A
+man, a plan, a canal: Panama!" and it works well in both PCRE and Perl. Note
+the use of the possessive quantifier *+ to avoid backtracking into sequences of
+non-word characters. Without this, PCRE takes a great deal longer (ten times or
+more) to match typical phrases, and Perl takes so long that you think it has
+gone into a loop.
+

+

+WARNING: The palindrome-matching patterns above work only if the subject
+string does not start with a palindrome that is shorter than the entire string.
+For example, although "abcba" is correctly matched, if the subject is "ababa",
+PCRE finds the palindrome "aba" at the start, then fails at top level because
+the end of the string does not follow. Once again, it cannot jump back into the
+recursion to try other alternatives, so the entire match fails.
+

+

+The second way in which PCRE and Perl differ in their recursion processing is
+in the handling of captured values. In Perl, when a subpattern is called
+recursively or as a subpattern (see the next section), it has no access to any
+values that were captured outside the recursion, whereas in PCRE these values
+can be referenced. Consider this pattern:
+
+  ^(.)(\1|a(?2))
+

+In PCRE, this pattern matches "bab". The first capturing parentheses match "b",
+then in the second group, when the back reference \1 fails to match "b", the
+second alternative matches "a" and then recurses. In the recursion, \1 does
+now match "b" and so the whole match succeeds. In Perl, the pattern fails to
+match because inside the recursive call \1 cannot access the externally set
+value.
+

+
SUBPATTERNS AS SUBROUTINES

+

+If the syntax for a recursive subpattern call (either by number or by
+name) is used outside the parentheses to which it refers, it operates like a
+subroutine in a programming language. The called subpattern may be defined
+before or after the reference. A numbered reference can be absolute or
+relative, as in these examples:
+
+  (...(absolute)...)...(?2)...
+  (...(relative)...)...(?-1)...
+  (...(?+1)...(relative)...
+

+An earlier example pointed out that the pattern
+
+  (sens|respons)e and \1ibility
+

+matches "sense and sensibility" and "response and responsibility", but not
+"sense and responsibility". If instead the pattern
+
+  (sens|respons)e and (?1)ibility
+

+is used, it does match "sense and responsibility" as well as the other two
+strings. Another example is given in the discussion of DEFINE above.
+

+

+All subroutine calls, whether recursive or not, are always treated as atomic
+groups. That is, once a subroutine has matched some of the subject string, it
+is never re-entered, even if it contains untried alternatives and there is a
+subsequent matching failure. Any capturing parentheses that are set during the
+subroutine call revert to their previous values afterwards.
+

+

+Processing options such as case-independence are fixed when a subpattern is
+defined, so if it is used as a subroutine, such options cannot be changed for
+different calls. For example, consider this pattern:
+
+  (abc)(?i:(?-1))
+

+It matches "abcabc". It does not match "abcABC" because the change of
+processing option does not affect the called subpattern.
+

+
ONIGURUMA SUBROUTINE SYNTAX

+

+For compatibility with Oniguruma, the non-Perl syntax \g followed by a name or
+a number enclosed either in angle brackets or single quotes, is an alternative
+syntax for referencing a subpattern as a subroutine, possibly recursively. Here
+are two of the examples used above, rewritten using this syntax:
+
+  (?<pn> \( ( (?>[^()]+) | \g<pn> )* \) )
+  (sens|respons)e and \g'1'ibility
+

+PCRE supports an extension to Oniguruma: if a number is preceded by a
+plus or a minus sign it is taken as a relative reference. For example:
+
+  (abc)(?i:\g<-1>)
+

+Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not
+synonymous. The former is a back reference; the latter is a subroutine call.
+

+
CALLOUTS

+

+Perl has a feature whereby using the sequence (?{...}) causes arbitrary Perl
+code to be obeyed in the middle of matching a regular expression. This makes it
+possible, amongst other things, to extract different substrings that match the
+same pair of parentheses when there is a repetition.
+

+

+PCRE provides a similar feature, but of course it cannot obey arbitrary Perl
+code. The feature is called "callout". The caller of PCRE provides an external
+function by putting its entry point in the global variable pcre_callout
+(8-bit library) or pcre[16|32]_callout (16-bit or 32-bit library).
+By default, this variable contains NULL, which disables all calling out.
+

+

+Within a regular expression, (?C) indicates the points at which the external
+function is to be called. If you want to identify different callout points, you
+can put a number less than 256 after the letter C. The default value is zero.
+For example, this pattern has two callout points:
+
+  (?C1)abc(?C2)def
+

+If the PCRE_AUTO_CALLOUT flag is passed to a compiling function, callouts are
+automatically installed before each item in the pattern. They are all numbered
+255. If there is a conditional group in the pattern whose condition is an
+assertion, an additional callout is inserted just before the condition. An
+explicit callout may also be set at this position, as in this example:
+
+  (?(?C9)(?=a)abc|def)
+

+Note that this applies only to assertion conditions, not to other types of
+condition.
+

+

+During matching, when PCRE reaches a callout point, the external function is
+called. It is provided with the number of the callout, the position in the
+pattern, and, optionally, one item of data originally supplied by the caller of
+the matching function. The callout function may cause matching to proceed, to
+backtrack, or to fail altogether.
+

+

+By default, PCRE implements a number of optimizations at compile time and
+matching time, and one side-effect is that sometimes callouts are skipped. If
+you need all possible callouts to happen, you need to set options that disable
+the relevant optimizations. More details, and a complete description of the
+interface to the callout function, are given in the
+pcrecallout
+documentation.
+

+
BACKTRACKING CONTROL

+

+Perl 5.10 introduced a number of "Special Backtracking Control Verbs", which
+are still described in the Perl documentation as "experimental and subject to
+change or removal in a future version of Perl". It goes on to say: "Their usage
+in production code should be noted to avoid problems during upgrades." The same
+remarks apply to the PCRE features described in this section.
+

+

+The new verbs make use of what was previously invalid syntax: an opening
+parenthesis followed by an asterisk. They are generally of the form
+(*VERB) or (*VERB:NAME). Some may take either form, possibly behaving
+differently depending on whether or not a name is present. A name is any
+sequence of characters that does not include a closing parenthesis. The maximum
+length of name is 255 in the 8-bit library and 65535 in the 16-bit and 32-bit
+libraries. If the name is empty, that is, if the closing parenthesis
+immediately follows the colon, the effect is as if the colon were not there.
+Any number of these verbs may occur in a pattern.
+

+

+Since these verbs are specifically related to backtracking, most of them can be
+used only when the pattern is to be matched using one of the traditional
+matching functions, because these use a backtracking algorithm. With the
+exception of (*FAIL), which behaves like a failing negative assertion, the
+backtracking control verbs cause an error if encountered by a DFA matching
+function.
+

+

+The behaviour of these verbs in
+repeated groups,
+assertions,
+and in
+subpatterns called as subroutines
+(whether or not recursively) is documented below.
+

+

+Optimizations that affect backtracking verbs
+

+

+PCRE contains some optimizations that are used to speed up matching by running
+some checks at the start of each match attempt. For example, it may know the
+minimum length of matching subject, or that a particular character must be
+present. When one of these optimizations bypasses the running of a match, any
+included backtracking verbs will not, of course, be processed. You can suppress
+the start-of-match optimizations by setting the PCRE_NO_START_OPTIMIZE option
+when calling pcre_compile() or pcre_exec(), or by starting the
+pattern with (*NO_START_OPT). There is more discussion of this option in the
+section entitled
+"Option bits for pcre_exec()"
+in the
+pcreapi
+documentation.
+

+

+Experiments with Perl suggest that it too has similar optimizations, sometimes
+leading to anomalous results.
+

+

+Verbs that act immediately
+

+

+The following verbs act as soon as they are encountered. They may not be
+followed by a name.
+
+   (*ACCEPT)
+

+This verb causes the match to end successfully, skipping the remainder of the
+pattern. However, when it is inside a subpattern that is called as a
+subroutine, only that subpattern is ended successfully. Matching then continues
+at the outer level. If (*ACCEPT) in triggered in a positive assertion, the
+assertion succeeds; in a negative assertion, the assertion fails.
+

+

+If (*ACCEPT) is inside capturing parentheses, the data so far is captured. For
+example:
+
+  A((?:A|B(*ACCEPT)|C)D)
+

+This matches "AB", "AAD", or "ACD"; when it matches "AB", "B" is captured by
+the outer parentheses.
+
+  (*FAIL) or (*F)
+

+This verb causes a matching failure, forcing backtracking to occur. It is
+equivalent to (?!) but easier to read. The Perl documentation notes that it is
+probably useful only when combined with (?{}) or (??{}). Those are, of course,
+Perl features that are not present in PCRE. The nearest equivalent is the
+callout feature, as for example in this pattern:
+
+  a+(?C)(*FAIL)
+

+A match with the string "aaaa" always fails, but the callout is taken before
+each backtrack happens (in this example, 10 times).
+

+

+Recording which path was taken
+

+

+There is one verb whose main purpose is to track how a match was arrived at,
+though it also has a secondary use in conjunction with advancing the match
+starting point (see (*SKIP) below).
+
+  (*MARK:NAME) or (*:NAME)
+

+A name is always required with this verb. There may be as many instances of
+(*MARK) as you like in a pattern, and their names do not have to be unique.
+

+

+When a match succeeds, the name of the last-encountered (*MARK:NAME),
+(*PRUNE:NAME), or (*THEN:NAME) on the matching path is passed back to the
+caller as described in the section entitled
+"Extra data for pcre_exec()"
+in the
+pcreapi
+documentation. Here is an example of pcretest output, where the /K
+modifier requests the retrieval and outputting of (*MARK) data:
+
+    re> /X(*MARK:A)Y|X(*MARK:B)Z/K
+  data> XY
+   0: XY
+  MK: A
+  XZ
+   0: XZ
+  MK: B
+

+The (*MARK) name is tagged with "MK:" in this output, and in this example it
+indicates which of the two alternatives matched. This is a more efficient way
+of obtaining this information than putting each alternative in its own
+capturing parentheses.
+

+

+If a verb with a name is encountered in a positive assertion that is true, the
+name is recorded and passed back if it is the last-encountered. This does not
+happen for negative assertions or failing positive assertions.
+

+

+After a partial match or a failed match, the last encountered name in the
+entire match process is returned. For example:
+
+    re> /X(*MARK:A)Y|X(*MARK:B)Z/K
+  data> XP
+  No match, mark = B
+

+Note that in this unanchored example the mark is retained from the match
+attempt that started at the letter "X" in the subject. Subsequent match
+attempts starting at "P" and then with an empty string do not get as far as the
+(*MARK) item, but nevertheless do not reset it.
+

+

+If you are interested in (*MARK) values after failed matches, you should
+probably set the PCRE_NO_START_OPTIMIZE option
+(see above)
+to ensure that the match is always attempted.
+

+

+Verbs that act after backtracking
+

+

+The following verbs do nothing when they are encountered. Matching continues
+with what follows, but if there is no subsequent match, causing a backtrack to
+the verb, a failure is forced. That is, backtracking cannot pass to the left of
+the verb. However, when one of these verbs appears inside an atomic group or an
+assertion that is true, its effect is confined to that group, because once the
+group has been matched, there is never any backtracking into it. In this
+situation, backtracking can "jump back" to the left of the entire atomic group
+or assertion. (Remember also, as stated above, that this localization also
+applies in subroutine calls.)
+

+

+These verbs differ in exactly what kind of failure occurs when backtracking
+reaches them. The behaviour described below is what happens when the verb is
+not in a subroutine or an assertion. Subsequent sections cover these special
+cases.
+
+  (*COMMIT)
+

+This verb, which may not be followed by a name, causes the whole match to fail
+outright if there is a later matching failure that causes backtracking to reach
+it. Even if the pattern is unanchored, no further attempts to find a match by
+advancing the starting point take place. If (*COMMIT) is the only backtracking
+verb that is encountered, once it has been passed pcre_exec() is
+committed to finding a match at the current starting point, or not at all. For
+example:
+
+  a+(*COMMIT)b
+

+This matches "xxaab" but not "aacaab". It can be thought of as a kind of
+dynamic anchor, or "I've started, so I must finish." The name of the most
+recently passed (*MARK) in the path is passed back when (*COMMIT) forces a
+match failure.
+

+

+If there is more than one backtracking verb in a pattern, a different one that
+follows (*COMMIT) may be triggered first, so merely passing (*COMMIT) during a
+match does not always guarantee that a match must be at this starting point.
+

+

+Note that (*COMMIT) at the start of a pattern is not the same as an anchor,
+unless PCRE's start-of-match optimizations are turned off, as shown in this
+output from pcretest:
+
+    re> /(*COMMIT)abc/
+  data> xyzabc
+   0: abc
+  data> xyzabc\Y
+  No match
+

+For this pattern, PCRE knows that any match must start with "a", so the
+optimization skips along the subject to "a" before applying the pattern to the
+first set of data. The match attempt then succeeds. In the second set of data,
+the escape sequence \Y is interpreted by the pcretest program. It causes
+the PCRE_NO_START_OPTIMIZE option to be set when pcre_exec() is called.
+This disables the optimization that skips along to the first character. The
+pattern is now applied starting at "x", and so the (*COMMIT) causes the match
+to fail without trying any other starting points.
+
+  (*PRUNE) or (*PRUNE:NAME)
+

+This verb causes the match to fail at the current starting position in the
+subject if there is a later matching failure that causes backtracking to reach
+it. If the pattern is unanchored, the normal "bumpalong" advance to the next
+starting character then happens. Backtracking can occur as usual to the left of
+(*PRUNE), before it is reached, or when matching to the right of (*PRUNE), but
+if there is no match to the right, backtracking cannot cross (*PRUNE). In
+simple cases, the use of (*PRUNE) is just an alternative to an atomic group or
+possessive quantifier, but there are some uses of (*PRUNE) that cannot be
+expressed in any other way. In an anchored pattern (*PRUNE) has the same effect
+as (*COMMIT).
+

+

+The behaviour of (*PRUNE:NAME) is the not the same as (*MARK:NAME)(*PRUNE).
+It is like (*MARK:NAME) in that the name is remembered for passing back to the
+caller. However, (*SKIP:NAME) searches only for names set with (*MARK).
+
+  (*SKIP)
+

+This verb, when given without a name, is like (*PRUNE), except that if the
+pattern is unanchored, the "bumpalong" advance is not to the next character,
+but to the position in the subject where (*SKIP) was encountered. (*SKIP)
+signifies that whatever text was matched leading up to it cannot be part of a
+successful match. Consider:
+
+  a+(*SKIP)b
+

+If the subject is "aaaac...", after the first match attempt fails (starting at
+the first character in the string), the starting point skips on to start the
+next attempt at "c". Note that a possessive quantifer does not have the same
+effect as this example; although it would suppress backtracking during the
+first match attempt, the second attempt would start at the second character
+instead of skipping on to "c".
+
+  (*SKIP:NAME)
+

+When (*SKIP) has an associated name, its behaviour is modified. When it is
+triggered, the previous path through the pattern is searched for the most
+recent (*MARK) that has the same name. If one is found, the "bumpalong" advance
+is to the subject position that corresponds to that (*MARK) instead of to where
+(*SKIP) was encountered. If no (*MARK) with a matching name is found, the
+(*SKIP) is ignored.
+

+

+Note that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It ignores
+names that are set by (*PRUNE:NAME) or (*THEN:NAME).
+
+  (*THEN) or (*THEN:NAME)
+

+This verb causes a skip to the next innermost alternative when backtracking
+reaches it. That is, it cancels any further backtracking within the current
+alternative. Its name comes from the observation that it can be used for a
+pattern-based if-then-else block:
+
+  ( COND1 (*THEN) FOO | COND2 (*THEN) BAR | COND3 (*THEN) BAZ ) ...
+

+If the COND1 pattern matches, FOO is tried (and possibly further items after
+the end of the group if FOO succeeds); on failure, the matcher skips to the
+second alternative and tries COND2, without backtracking into COND1. If that
+succeeds and BAR fails, COND3 is tried. If subsequently BAZ fails, there are no
+more alternatives, so there is a backtrack to whatever came before the entire
+group. If (*THEN) is not inside an alternation, it acts like (*PRUNE).
+

+

+The behaviour of (*THEN:NAME) is the not the same as (*MARK:NAME)(*THEN).
+It is like (*MARK:NAME) in that the name is remembered for passing back to the
+caller. However, (*SKIP:NAME) searches only for names set with (*MARK).
+

+

+A subpattern that does not contain a | character is just a part of the
+enclosing alternative; it is not a nested alternation with only one
+alternative. The effect of (*THEN) extends beyond such a subpattern to the
+enclosing alternative. Consider this pattern, where A, B, etc. are complex
+pattern fragments that do not contain any | characters at this level:
+
+  A (B(*THEN)C) | D
+

+If A and B are matched, but there is a failure in C, matching does not
+backtrack into A; instead it moves to the next alternative, that is, D.
+However, if the subpattern containing (*THEN) is given an alternative, it
+behaves differently:
+
+  A (B(*THEN)C | (*FAIL)) | D
+

+The effect of (*THEN) is now confined to the inner subpattern. After a failure
+in C, matching moves to (*FAIL), which causes the whole subpattern to fail
+because there are no more alternatives to try. In this case, matching does now
+backtrack into A.
+

+

+Note that a conditional subpattern is not considered as having two
+alternatives, because only one is ever used. In other words, the | character in
+a conditional subpattern has a different meaning. Ignoring white space,
+consider:
+
+  ^.*? (?(?=a) a | b(*THEN)c )
+

+If the subject is "ba", this pattern does not match. Because .*? is ungreedy,
+it initially matches zero characters. The condition (?=a) then fails, the
+character "b" is matched, but "c" is not. At this point, matching does not
+backtrack to .*? as might perhaps be expected from the presence of the |
+character. The conditional subpattern is part of the single alternative that
+comprises the whole pattern, and so the match fails. (If there was a backtrack
+into .*?, allowing it to match "b", the match would succeed.)
+

+

+The verbs just described provide four different "strengths" of control when
+subsequent matching fails. (*THEN) is the weakest, carrying on the match at the
+next alternative. (*PRUNE) comes next, failing the match at the current
+starting position, but allowing an advance to the next character (for an
+unanchored pattern). (*SKIP) is similar, except that the advance may be more
+than one character. (*COMMIT) is the strongest, causing the entire match to
+fail.
+

+

+More than one backtracking verb
+

+

+If more than one backtracking verb is present in a pattern, the one that is
+backtracked onto first acts. For example, consider this pattern, where A, B,
+etc. are complex pattern fragments:
+
+  (A(*COMMIT)B(*THEN)C|ABD)
+

+If A matches but B fails, the backtrack to (*COMMIT) causes the entire match to
+fail. However, if A and B match, but C fails, the backtrack to (*THEN) causes
+the next alternative (ABD) to be tried. This behaviour is consistent, but is
+not always the same as Perl's. It means that if two or more backtracking verbs
+appear in succession, all the the last of them has no effect. Consider this
+example:
+
+  ...(*COMMIT)(*PRUNE)...
+

+If there is a matching failure to the right, backtracking onto (*PRUNE) causes
+it to be triggered, and its action is taken. There can never be a backtrack
+onto (*COMMIT).
+

+

+Backtracking verbs in repeated groups
+

+

+PCRE differs from Perl in its handling of backtracking verbs in repeated
+groups. For example, consider:
+
+  /(a(*COMMIT)b)+ac/
+

+If the subject is "abac", Perl matches, but PCRE fails because the (*COMMIT) in
+the second repeat of the group acts.
+

+

+Backtracking verbs in assertions
+

+

+(*FAIL) in an assertion has its normal effect: it forces an immediate backtrack.
+

+

+(*ACCEPT) in a positive assertion causes the assertion to succeed without any
+further processing. In a negative assertion, (*ACCEPT) causes the assertion to
+fail without any further processing.
+

+

+The other backtracking verbs are not treated specially if they appear in a
+positive assertion. In particular, (*THEN) skips to the next alternative in the
+innermost enclosing group that has alternations, whether or not this is within
+the assertion.
+

+

+Negative assertions are, however, different, in order to ensure that changing a
+positive assertion into a negative assertion changes its result. Backtracking
+into (*COMMIT), (*SKIP), or (*PRUNE) causes a negative assertion to be true,
+without considering any further alternative branches in the assertion.
+Backtracking into (*THEN) causes it to skip to the next enclosing alternative
+within the assertion (the normal behaviour), but if the assertion does not have
+such an alternative, (*THEN) behaves like (*PRUNE).
+

+

+Backtracking verbs in subroutines
+

+

+These behaviours occur whether or not the subpattern is called recursively.
+Perl's treatment of subroutines is different in some cases.
+

+

+(*FAIL) in a subpattern called as a subroutine has its normal effect: it forces
+an immediate backtrack.
+

+

+(*ACCEPT) in a subpattern called as a subroutine causes the subroutine match to
+succeed without any further processing. Matching then continues after the
+subroutine call.
+

+

+(*COMMIT), (*SKIP), and (*PRUNE) in a subpattern called as a subroutine cause
+the subroutine match to fail.
+

+

+(*THEN) skips to the next alternative in the innermost enclosing group within
+the subpattern that has alternatives. If there is no such group within the
+subpattern, (*THEN) causes the subroutine match to fail.
+

+
SEE ALSO

+

+pcreapi(3), pcrecallout(3), pcrematching(3),
+pcresyntax(3), pcre(3), pcre16(3), pcre32(3).
+

+
AUTHOR

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+
REVISION

+

+Last updated: 08 January 2014
+

+Copyright © 1997-2014 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcreperform.html b/doc/html/pcreperform.html
new file mode 100644
index 0000000..dda207f
--- /dev/null
+++ b/doc/html/pcreperform.html
@@ -0,0 +1,195 @@
+
+
+pcreperform specification
+
+
+
pcreperform man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+PCRE PERFORMANCE
+

+

+Two aspects of performance are discussed below: memory usage and processing
+time. The way you express your pattern as a regular expression can affect both
+of them.
+

+

+COMPILED PATTERN MEMORY USAGE
+

+

+Patterns are compiled by PCRE into a reasonably efficient interpretive code, so
+that most simple patterns do not use much memory. However, there is one case
+where the memory usage of a compiled pattern can be unexpectedly large. If a
+parenthesized subpattern has a quantifier with a minimum greater than 1 and/or
+a limited maximum, the whole subpattern is repeated in the compiled code. For
+example, the pattern
+
+  (abc|def){2,4}
+

+is compiled as if it were
+
+  (abc|def)(abc|def)((abc|def)(abc|def)?)?
+

+(Technical aside: It is done this way so that backtrack points within each of
+the repetitions can be independently maintained.)
+

+

+For regular expressions whose quantifiers use only small numbers, this is not
+usually a problem. However, if the numbers are large, and particularly if such
+repetitions are nested, the memory usage can become an embarrassment. For
+example, the very simple pattern
+
+  ((ab){1,1000}c){1,3}
+

+uses 51K bytes when compiled using the 8-bit library. When PCRE is compiled
+with its default internal pointer size of two bytes, the size limit on a
+compiled pattern is 64K data units, and this is reached with the above pattern
+if the outer repetition is increased from 3 to 4. PCRE can be compiled to use
+larger internal pointers and thus handle larger compiled patterns, but it is
+better to try to rewrite your pattern to use less memory if you can.
+

+

+One way of reducing the memory usage for such patterns is to make use of PCRE's
+"subroutine"
+facility. Re-writing the above pattern as
+
+  ((ab)(?2){0,999}c)(?1){0,2}
+

+reduces the memory requirements to 18K, and indeed it remains under 20K even
+with the outer repetition increased to 100. However, this pattern is not
+exactly equivalent, because the "subroutine" calls are treated as
+atomic groups
+into which there can be no backtracking if there is a subsequent matching
+failure. Therefore, PCRE cannot do this kind of rewriting automatically.
+Furthermore, there is a noticeable loss of speed when executing the modified
+pattern. Nevertheless, if the atomic grouping is not a problem and the loss of
+speed is acceptable, this kind of rewriting will allow you to process patterns
+that PCRE cannot otherwise handle.
+

+

+STACK USAGE AT RUN TIME
+

+

+When pcre_exec() or pcre[16|32]_exec() is used for matching, certain
+kinds of pattern can cause it to use large amounts of the process stack. In
+some environments the default process stack is quite small, and if it runs out
+the result is often SIGSEGV. This issue is probably the most frequently raised
+problem with PCRE. Rewriting your pattern can often help. The
+pcrestack
+documentation discusses this issue in detail.
+

+

+PROCESSING TIME
+

+

+Certain items in regular expression patterns are processed more efficiently
+than others. It is more efficient to use a character class like [aeiou] than a
+set of single-character alternatives such as (a|e|i|o|u). In general, the
+simplest construction that provides the required behaviour is usually the most
+efficient. Jeffrey Friedl's book contains a lot of useful general discussion
+about optimizing regular expressions for efficient performance. This document
+contains a few observations about PCRE.
+

+

+Using Unicode character properties (the \p, \P, and \X escapes) is slow,
+because PCRE has to use a multi-stage table lookup whenever it needs a
+character's property. If you can find an alternative pattern that does not use
+character properties, it will probably be faster.
+

+

+By default, the escape sequences \b, \d, \s, and \w, and the POSIX
+character classes such as [:alpha:] do not use Unicode properties, partly for
+backwards compatibility, and partly for performance reasons. However, you can
+set PCRE_UCP if you want Unicode character properties to be used. This can
+double the matching time for items such as \d, when matched with
+a traditional matching function; the performance loss is less with
+a DFA matching function, and in both cases there is not much difference for
+\b.
+

+

+When a pattern begins with .* not in parentheses, or in parentheses that are
+not the subject of a backreference, and the PCRE_DOTALL option is set, the
+pattern is implicitly anchored by PCRE, since it can match only at the start of
+a subject string. However, if PCRE_DOTALL is not set, PCRE cannot make this
+optimization, because the . metacharacter does not then match a newline, and if
+the subject string contains newlines, the pattern may match from the character
+immediately following one of them instead of from the very start. For example,
+the pattern
+
+  .*second
+

+matches the subject "first\nand second" (where \n stands for a newline
+character), with the match starting at the seventh character. In order to do
+this, PCRE has to retry the match starting after every newline in the subject.
+

+

+If you are using such a pattern with subject strings that do not contain
+newlines, the best performance is obtained by setting PCRE_DOTALL, or starting
+the pattern with ^.* or ^.*? to indicate explicit anchoring. That saves PCRE
+from having to scan along the subject looking for a newline to restart at.
+

+

+Beware of patterns that contain nested indefinite repeats. These can take a
+long time to run when applied to a string that does not match. Consider the
+pattern fragment
+
+  ^(a+)*
+

+This can match "aaaa" in 16 different ways, and this number increases very
+rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4
+times, and for each of those cases other than 0 or 4, the + repeats can match
+different numbers of times.) When the remainder of the pattern is such that the
+entire match is going to fail, PCRE has in principle to try every possible
+variation, and this can take an extremely long time, even for relatively short
+strings.
+

+

+An optimization catches some of the more simple cases such as
+
+  (a+)*b
+

+where a literal character follows. Before embarking on the standard matching
+procedure, PCRE checks that there is a "b" later in the subject string, and if
+there is not, it fails the match immediately. However, when there is no
+following literal this optimization cannot be used. You can see the difference
+by comparing the behaviour of
+
+  (a+)*\d
+

+with the pattern above. The former gives a failure almost instantly when
+applied to a whole line of "a" characters, whereas the latter takes an
+appreciable time with strings longer than about 20 characters.
+

+

+In many cases, the solution to this kind of performance issue is to use an
+atomic group or a possessive quantifier.
+

+

+AUTHOR
+

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+

+REVISION
+

+

+Last updated: 25 August 2012
+

+Copyright © 1997-2012 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcreposix.html b/doc/html/pcreposix.html
new file mode 100644
index 0000000..18924cf
--- /dev/null
+++ b/doc/html/pcreposix.html
@@ -0,0 +1,290 @@
+
+
+pcreposix specification
+
+
+
pcreposix man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+
SYNOPSIS

+

+#include <pcreposix.h>
+

+

+int regcomp(regex_t *preg, const char *pattern,
+     int cflags);
+

+

+int regexec(regex_t *preg, const char *string,
+     size_t nmatch, regmatch_t pmatch[], int eflags);
+     size_t regerror(int errcode, const regex_t *preg,
+     char *errbuf, size_t errbuf_size);
+

+

+void regfree(regex_t *preg);
+

+
DESCRIPTION

+

+This set of functions provides a POSIX-style API for the PCRE regular
+expression 8-bit library. See the
+pcreapi
+documentation for a description of PCRE's native API, which contains much
+additional functionality. There is no POSIX-style wrapper for PCRE's 16-bit
+and 32-bit library.
+

+

+The functions described here are just wrapper functions that ultimately call
+the PCRE native API. Their prototypes are defined in the pcreposix.h
+header file, and on Unix systems the library itself is called
+pcreposix.a, so can be accessed by adding -lpcreposix to the
+command for linking an application that uses them. Because the POSIX functions
+call the native ones, it is also necessary to add -lpcre.
+

+

+I have implemented only those POSIX option bits that can be reasonably mapped
+to PCRE native options. In addition, the option REG_EXTENDED is defined with
+the value zero. This has no effect, but since programs that are written to the
+POSIX interface often use it, this makes it easier to slot in PCRE as a
+replacement library. Other POSIX options are not even defined.
+

+

+There are also some other options that are not defined by POSIX. These have
+been added at the request of users who want to make use of certain
+PCRE-specific features via the POSIX calling interface.
+

+

+When PCRE is called via these functions, it is only the API that is POSIX-like
+in style. The syntax and semantics of the regular expressions themselves are
+still those of Perl, subject to the setting of various PCRE options, as
+described below. "POSIX-like in style" means that the API approximates to the
+POSIX definition; it is not fully POSIX-compatible, and in multi-byte encoding
+domains it is probably even less compatible.
+

+

+The header for these functions is supplied as pcreposix.h to avoid any
+potential clash with other POSIX libraries. It can, of course, be renamed or
+aliased as regex.h, which is the "correct" name. It provides two
+structure types, regex_t for compiled internal forms, and
+regmatch_t for returning captured substrings. It also defines some
+constants whose names start with "REG_"; these are used for setting options and
+identifying error codes.
+

+
COMPILING A PATTERN

+

+The function regcomp() is called to compile a pattern into an
+internal form. The pattern is a C string terminated by a binary zero, and
+is passed in the argument pattern. The preg argument is a pointer
+to a regex_t structure that is used as a base for storing information
+about the compiled regular expression.
+

+

+The argument cflags is either zero, or contains one or more of the bits
+defined by the following macros:
+
+  REG_DOTALL
+

+The PCRE_DOTALL option is set when the regular expression is passed for
+compilation to the native function. Note that REG_DOTALL is not part of the
+POSIX standard.
+
+  REG_ICASE
+

+The PCRE_CASELESS option is set when the regular expression is passed for
+compilation to the native function.
+
+  REG_NEWLINE
+

+The PCRE_MULTILINE option is set when the regular expression is passed for
+compilation to the native function. Note that this does not mimic the
+defined POSIX behaviour for REG_NEWLINE (see the following section).
+
+  REG_NOSUB
+

+The PCRE_NO_AUTO_CAPTURE option is set when the regular expression is passed
+for compilation to the native function. In addition, when a pattern that is
+compiled with this flag is passed to regexec() for matching, the
+nmatch and pmatch arguments are ignored, and no captured strings
+are returned.
+
+  REG_UCP
+

+The PCRE_UCP option is set when the regular expression is passed for
+compilation to the native function. This causes PCRE to use Unicode properties
+when matchine \d, \w, etc., instead of just recognizing ASCII values. Note
+that REG_UTF8 is not part of the POSIX standard.
+
+  REG_UNGREEDY
+

+The PCRE_UNGREEDY option is set when the regular expression is passed for
+compilation to the native function. Note that REG_UNGREEDY is not part of the
+POSIX standard.
+
+  REG_UTF8
+

+The PCRE_UTF8 option is set when the regular expression is passed for
+compilation to the native function. This causes the pattern itself and all data
+strings used for matching it to be treated as UTF-8 strings. Note that REG_UTF8
+is not part of the POSIX standard.
+

+

+In the absence of these flags, no options are passed to the native function.
+This means the the regex is compiled with PCRE default semantics. In
+particular, the way it handles newline characters in the subject string is the
+Perl way, not the POSIX way. Note that setting PCRE_MULTILINE has only
+some of the effects specified for REG_NEWLINE. It does not affect the way
+newlines are matched by . (they are not) or by a negative class such as [^a]
+(they are).
+

+

+The yield of regcomp() is zero on success, and non-zero otherwise. The
+preg structure is filled in on success, and one member of the structure
+is public: re_nsub contains the number of capturing subpatterns in
+the regular expression. Various error codes are defined in the header file.
+

+

+NOTE: If the yield of regcomp() is non-zero, you must not attempt to
+use the contents of the preg structure. If, for example, you pass it to
+regexec(), the result is undefined and your program is likely to crash.
+

+
MATCHING NEWLINE CHARACTERS

+

+This area is not simple, because POSIX and Perl take different views of things.
+It is not possible to get PCRE to obey POSIX semantics, but then PCRE was never
+intended to be a POSIX engine. The following table lists the different
+possibilities for matching newline characters in PCRE:
+
+                          Default   Change with
+
+  . matches newline          no     PCRE_DOTALL
+  newline matches [^a]       yes    not changeable
+  $ matches \n at end        yes    PCRE_DOLLARENDONLY
+  $ matches \n in middle     no     PCRE_MULTILINE
+  ^ matches \n in middle     no     PCRE_MULTILINE
+

+This is the equivalent table for POSIX:
+
+                          Default   Change with
+
+  . matches newline          yes    REG_NEWLINE
+  newline matches [^a]       yes    REG_NEWLINE
+  $ matches \n at end        no     REG_NEWLINE
+  $ matches \n in middle     no     REG_NEWLINE
+  ^ matches \n in middle     no     REG_NEWLINE
+

+PCRE's behaviour is the same as Perl's, except that there is no equivalent for
+PCRE_DOLLAR_ENDONLY in Perl. In both PCRE and Perl, there is no way to stop
+newline from matching [^a].
+

+

+The default POSIX newline handling can be obtained by setting PCRE_DOTALL and
+PCRE_DOLLAR_ENDONLY, but there is no way to make PCRE behave exactly as for the
+REG_NEWLINE action.
+

+
MATCHING A PATTERN

+

+The function regexec() is called to match a compiled pattern preg
+against a given string, which is by default terminated by a zero byte
+(but see REG_STARTEND below), subject to the options in eflags. These can
+be:
+
+  REG_NOTBOL
+

+The PCRE_NOTBOL option is set when calling the underlying PCRE matching
+function.
+
+  REG_NOTEMPTY
+

+The PCRE_NOTEMPTY option is set when calling the underlying PCRE matching
+function. Note that REG_NOTEMPTY is not part of the POSIX standard. However,
+setting this option can give more POSIX-like behaviour in some situations.
+
+  REG_NOTEOL
+

+The PCRE_NOTEOL option is set when calling the underlying PCRE matching
+function.
+
+  REG_STARTEND
+

+The string is considered to start at string + pmatch[0].rm_so and
+to have a terminating NUL located at string + pmatch[0].rm_eo
+(there need not actually be a NUL at that location), regardless of the value of
+nmatch. This is a BSD extension, compatible with but not specified by
+IEEE Standard 1003.2 (POSIX.2), and should be used with caution in software
+intended to be portable to other systems. Note that a non-zero rm_so does
+not imply REG_NOTBOL; REG_STARTEND affects only the location of the string, not
+how it is matched.
+

+

+If the pattern was compiled with the REG_NOSUB flag, no data about any matched
+strings is returned. The nmatch and pmatch arguments of
+regexec() are ignored.
+

+

+If the value of nmatch is zero, or if the value pmatch is NULL,
+no data about any matched strings is returned.
+

+

+Otherwise,the portion of the string that was matched, and also any captured
+substrings, are returned via the pmatch argument, which points to an
+array of nmatch structures of type regmatch_t, containing the
+members rm_so and rm_eo. These contain the offset to the first
+character of each substring and the offset to the first character after the end
+of each substring, respectively. The 0th element of the vector relates to the
+entire portion of string that was matched; subsequent elements relate to
+the capturing subpatterns of the regular expression. Unused entries in the
+array have both structure members set to -1.
+

+

+A successful match yields a zero return; various error codes are defined in the
+header file, of which REG_NOMATCH is the "expected" failure code.
+

+
ERROR MESSAGES

+

+The regerror() function maps a non-zero errorcode from either
+regcomp() or regexec() to a printable message. If preg is not
+NULL, the error should have arisen from the use of that structure. A message
+terminated by a binary zero is placed in errbuf. The length of the
+message, including the zero, is limited to errbuf_size. The yield of the
+function is the size of buffer needed to hold the whole message.
+

+
MEMORY USAGE

+

+Compiling a regular expression causes memory to be allocated and associated
+with the preg structure. The function regfree() frees all such
+memory, after which preg may no longer be used as a compiled expression.
+

+
AUTHOR

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+
REVISION

+

+Last updated: 09 January 2012
+

+Copyright © 1997-2012 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcreprecompile.html b/doc/html/pcreprecompile.html
new file mode 100644
index 0000000..decb1d6
--- /dev/null
+++ b/doc/html/pcreprecompile.html
@@ -0,0 +1,163 @@
+
+
+pcreprecompile specification
+
+
+
pcreprecompile man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+
SAVING AND RE-USING PRECOMPILED PCRE PATTERNS

+

+If you are running an application that uses a large number of regular
+expression patterns, it may be useful to store them in a precompiled form
+instead of having to compile them every time the application is run.
+If you are not using any private character tables (see the
+pcre_maketables()
+documentation), this is relatively straightforward. If you are using private
+tables, it is a little bit more complicated. However, if you are using the
+just-in-time optimization feature, it is not possible to save and reload the
+JIT data.
+

+

+If you save compiled patterns to a file, you can copy them to a different host
+and run them there. If the two hosts have different endianness (byte order),
+you should run the pcre[16|32]_pattern_to_host_byte_order() function on the
+new host before trying to match the pattern. The matching functions return
+PCRE_ERROR_BADENDIANNESS if they detect a pattern with the wrong endianness.
+

+

+Compiling regular expressions with one version of PCRE for use with a different
+version is not guaranteed to work and may cause crashes, and saving and
+restoring a compiled pattern loses any JIT optimization data.
+

+
SAVING A COMPILED PATTERN

+

+The value returned by pcre[16|32]_compile() points to a single block of
+memory that holds the compiled pattern and associated data. You can find the
+length of this block in bytes by calling pcre[16|32]_fullinfo() with an
+argument of PCRE_INFO_SIZE. You can then save the data in any appropriate
+manner. Here is sample code for the 8-bit library that compiles a pattern and
+writes it to a file. It assumes that the variable fd refers to a file
+that is open for output:
+
+  int erroroffset, rc, size;
+  char *error;
+  pcre *re;
+
+  re = pcre_compile("my pattern", 0, &error, &erroroffset, NULL);
+  if (re == NULL) { ... handle errors ... }
+  rc = pcre_fullinfo(re, NULL, PCRE_INFO_SIZE, &size);
+  if (rc < 0) { ... handle errors ... }
+  rc = fwrite(re, 1, size, fd);
+  if (rc != size) { ... handle errors ... }
+

+In this example, the bytes that comprise the compiled pattern are copied
+exactly. Note that this is binary data that may contain any of the 256 possible
+byte values. On systems that make a distinction between binary and non-binary
+data, be sure that the file is opened for binary output.
+

+

+If you want to write more than one pattern to a file, you will have to devise a
+way of separating them. For binary data, preceding each pattern with its length
+is probably the most straightforward approach. Another possibility is to write
+out the data in hexadecimal instead of binary, one pattern to a line.
+

+

+Saving compiled patterns in a file is only one possible way of storing them for
+later use. They could equally well be saved in a database, or in the memory of
+some daemon process that passes them via sockets to the processes that want
+them.
+

+

+If the pattern has been studied, it is also possible to save the normal study
+data in a similar way to the compiled pattern itself. However, if the
+PCRE_STUDY_JIT_COMPILE was used, the just-in-time data that is created cannot
+be saved because it is too dependent on the current environment. When studying
+generates additional information, pcre[16|32]_study() returns a pointer to a
+pcre[16|32]_extra data block. Its format is defined in the
+section on matching a pattern
+in the
+pcreapi
+documentation. The study_data field points to the binary study data, and
+this is what you must save (not the pcre[16|32]_extra block itself). The
+length of the study data can be obtained by calling pcre[16|32]_fullinfo()
+with an argument of PCRE_INFO_STUDYSIZE. Remember to check that
+pcre[16|32]_study() did return a non-NULL value before trying to save the
+study data.
+

+
RE-USING A PRECOMPILED PATTERN

+

+Re-using a precompiled pattern is straightforward. Having reloaded it into main
+memory, called pcre[16|32]_pattern_to_host_byte_order() if necessary, you
+pass its pointer to pcre[16|32]_exec() or pcre[16|32]_dfa_exec() in
+the usual way.
+

+

+However, if you passed a pointer to custom character tables when the pattern
+was compiled (the tableptr argument of pcre[16|32]_compile()), you
+must now pass a similar pointer to pcre[16|32]_exec() or
+pcre[16|32]_dfa_exec(), because the value saved with the compiled pattern
+will obviously be nonsense. A field in a pcre[16|32]_extra() block is used
+to pass this data, as described in the
+section on matching a pattern
+in the
+pcreapi
+documentation.
+

+

+Warning: The tables that pcre_exec() and pcre_dfa_exec() use
+must be the same as those that were used when the pattern was compiled. If this
+is not the case, the behaviour is undefined.
+

+

+If you did not provide custom character tables when the pattern was compiled,
+the pointer in the compiled pattern is NULL, which causes the matching
+functions to use PCRE's internal tables. Thus, you do not need to take any
+special action at run time in this case.
+

+

+If you saved study data with the compiled pattern, you need to create your own
+pcre[16|32]_extra data block and set the study_data field to point
+to the reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in
+the flags field to indicate that study data is present. Then pass the
+pcre[16|32]_extra block to the matching function in the usual way. If the
+pattern was studied for just-in-time optimization, that data cannot be saved,
+and so is lost by a save/restore cycle.
+

+
COMPATIBILITY WITH DIFFERENT PCRE RELEASES

+

+In general, it is safest to recompile all saved patterns when you update to a
+new PCRE release, though not all updates actually require this.
+

+
AUTHOR

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+
REVISION

+

+Last updated: 12 November 2013
+

+Copyright © 1997-2013 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcresample.html b/doc/html/pcresample.html
new file mode 100644
index 0000000..aca9184
--- /dev/null
+++ b/doc/html/pcresample.html
@@ -0,0 +1,110 @@
+
+
+pcresample specification
+
+
+
pcresample man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+PCRE SAMPLE PROGRAM
+

+

+A simple, complete demonstration program, to get you started with using PCRE,
+is supplied in the file pcredemo.c in the PCRE distribution. A listing of
+this program is given in the
+pcredemo
+documentation. If you do not have a copy of the PCRE distribution, you can save
+this listing to re-create pcredemo.c.
+

+

+The demonstration program, which uses the original PCRE 8-bit library, compiles
+the regular expression that is its first argument, and matches it against the
+subject string in its second argument. No PCRE options are set, and default
+character tables are used. If matching succeeds, the program outputs the
+portion of the subject that matched, together with the contents of any captured
+substrings.
+

+

+If the -g option is given on the command line, the program then goes on to
+check for further matches of the same regular expression in the same subject
+string. The logic is a little bit tricky because of the possibility of matching
+an empty string. Comments in the code explain what is going on.
+

+

+If PCRE is installed in the standard include and library directories for your
+operating system, you should be able to compile the demonstration program using
+this command:
+
+  gcc -o pcredemo pcredemo.c -lpcre
+

+If PCRE is installed elsewhere, you may need to add additional options to the
+command line. For example, on a Unix-like system that has PCRE installed in
+/usr/local, you can compile the demonstration program using a command
+like this:
+
+  gcc -o pcredemo -I/usr/local/include pcredemo.c -L/usr/local/lib -lpcre
+

+In a Windows environment, if you want to statically link the program against a
+non-dll pcre.a file, you must uncomment the line that defines PCRE_STATIC
+before including pcre.h, because otherwise the pcre_malloc() and
+pcre_free() exported functions will be declared
+__declspec(dllimport), with unwanted results.
+

+

+Once you have compiled and linked the demonstration program, you can run simple
+tests like this:
+
+  ./pcredemo 'cat|dog' 'the cat sat on the mat'
+  ./pcredemo -g 'cat|dog' 'the dog sat on the cat'
+

+Note that there is a much more comprehensive test program, called
+pcretest,
+which supports many more facilities for testing regular expressions and both
+PCRE libraries. The
+pcredemo
+program is provided as a simple coding example.
+

+

+If you try to run
+pcredemo
+when PCRE is not installed in the standard library directory, you may get an
+error like this on some operating systems (e.g. Solaris):
+
+  ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory
+

+This is caused by the way shared library support works on those systems. You
+need to add
+
+  -R/usr/local/lib
+

+(for example) to the compile command to get round this problem.
+

+

+AUTHOR
+

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+

+REVISION
+

+

+Last updated: 10 January 2012
+

+Copyright © 1997-2012 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcrestack.html b/doc/html/pcrestack.html
new file mode 100644
index 0000000..af6406d
--- /dev/null
+++ b/doc/html/pcrestack.html
@@ -0,0 +1,225 @@
+
+
+pcrestack specification
+
+
+
pcrestack man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+PCRE DISCUSSION OF STACK USAGE
+

+

+When you call pcre[16|32]_exec(), it makes use of an internal function
+called match(). This calls itself recursively at branch points in the
+pattern, in order to remember the state of the match so that it can back up and
+try a different alternative if the first one fails. As matching proceeds deeper
+and deeper into the tree of possibilities, the recursion depth increases. The
+match() function is also called in other circumstances, for example,
+whenever a parenthesized sub-pattern is entered, and in certain cases of
+repetition.
+

+

+Not all calls of match() increase the recursion depth; for an item such
+as a* it may be called several times at the same level, after matching
+different numbers of a's. Furthermore, in a number of cases where the result of
+the recursive call would immediately be passed back as the result of the
+current call (a "tail recursion"), the function is just restarted instead.
+

+

+The above comments apply when pcre[16|32]_exec() is run in its normal
+interpretive manner. If the pattern was studied with the
+PCRE_STUDY_JIT_COMPILE option, and just-in-time compiling was successful, and
+the options passed to pcre[16|32]_exec() were not incompatible, the matching
+process uses the JIT-compiled code instead of the match() function. In
+this case, the memory requirements are handled entirely differently. See the
+pcrejit
+documentation for details.
+

+

+The pcre[16|32]_dfa_exec() function operates in an entirely different way,
+and uses recursion only when there is a regular expression recursion or
+subroutine call in the pattern. This includes the processing of assertion and
+"once-only" subpatterns, which are handled like subroutine calls. Normally,
+these are never very deep, and the limit on the complexity of
+pcre[16|32]_dfa_exec() is controlled by the amount of workspace it is given.
+However, it is possible to write patterns with runaway infinite recursions;
+such patterns will cause pcre[16|32]_dfa_exec() to run out of stack. At
+present, there is no protection against this.
+

+

+The comments that follow do NOT apply to pcre[16|32]_dfa_exec(); they are
+relevant only for pcre[16|32]_exec() without the JIT optimization.
+

+

+Reducing pcre[16|32]_exec()'s stack usage
+

+

+Each time that match() is actually called recursively, it uses memory
+from the process stack. For certain kinds of pattern and data, very large
+amounts of stack may be needed, despite the recognition of "tail recursion".
+You can often reduce the amount of recursion, and therefore the amount of stack
+used, by modifying the pattern that is being matched. Consider, for example,
+this pattern:
+
+  ([^<]|<(?!inet))+
+

+It matches from wherever it starts until it encounters "<inet" or the end of
+the data, and is the kind of pattern that might be used when processing an XML
+file. Each iteration of the outer parentheses matches either one character that
+is not "<" or a "<" that is not followed by "inet". However, each time a
+parenthesis is processed, a recursion occurs, so this formulation uses a stack
+frame for each matched character. For a long string, a lot of stack is
+required. Consider now this rewritten pattern, which matches exactly the same
+strings:
+
+  ([^<]++|<(?!inet))+
+

+This uses very much less stack, because runs of characters that do not contain
+"<" are "swallowed" in one item inside the parentheses. Recursion happens only
+when a "<" character that is not followed by "inet" is encountered (and we
+assume this is relatively rare). A possessive quantifier is used to stop any
+backtracking into the runs of non-"<" characters, but that is not related to
+stack usage.
+

+

+This example shows that one way of avoiding stack problems when matching long
+subject strings is to write repeated parenthesized subpatterns to match more
+than one character whenever possible.
+

+

+Compiling PCRE to use heap instead of stack for pcre[16|32]_exec()
+

+

+In environments where stack memory is constrained, you might want to compile
+PCRE to use heap memory instead of stack for remembering back-up points when
+pcre[16|32]_exec() is running. This makes it run a lot more slowly, however.
+Details of how to do this are given in the
+pcrebuild
+documentation. When built in this way, instead of using the stack, PCRE obtains
+and frees memory by calling the functions that are pointed to by the
+pcre[16|32]_stack_malloc and pcre[16|32]_stack_free variables. By
+default, these point to malloc() and free(), but you can replace
+the pointers to cause PCRE to use your own functions. Since the block sizes are
+always the same, and are always freed in reverse order, it may be possible to
+implement customized memory handlers that are more efficient than the standard
+functions.
+

+

+Limiting pcre[16|32]_exec()'s stack usage
+

+

+You can set limits on the number of times that match() is called, both in
+total and recursively. If a limit is exceeded, pcre[16|32]_exec() returns an
+error code. Setting suitable limits should prevent it from running out of
+stack. The default values of the limits are very large, and unlikely ever to
+operate. They can be changed when PCRE is built, and they can also be set when
+pcre[16|32]_exec() is called. For details of these interfaces, see the
+pcrebuild
+documentation and the
+section on extra data for pcre[16|32]_exec()
+in the
+pcreapi
+documentation.
+

+

+As a very rough rule of thumb, you should reckon on about 500 bytes per
+recursion. Thus, if you want to limit your stack usage to 8Mb, you should set
+the limit at 16000 recursions. A 64Mb stack, on the other hand, can support
+around 128000 recursions.
+

+

+In Unix-like environments, the pcretest test program has a command line
+option (-S) that can be used to increase the size of its stack. As long
+as the stack is large enough, another option (-M) can be used to find the
+smallest limits that allow a particular pattern to match a given subject
+string. This is done by calling pcre[16|32]_exec() repeatedly with different
+limits.
+

+

+Obtaining an estimate of stack usage
+

+

+The actual amount of stack used per recursion can vary quite a lot, depending
+on the compiler that was used to build PCRE and the optimization or debugging
+options that were set for it. The rule of thumb value of 500 bytes mentioned
+above may be larger or smaller than what is actually needed. A better
+approximation can be obtained by running this command:
+
+  pcretest -m -C
+

+The -C option causes pcretest to output information about the
+options with which PCRE was compiled. When -m is also given (before
+-C), information about stack use is given in a line like this:
+
+  Match recursion uses stack: approximate frame size = 640 bytes
+

+The value is approximate because some recursions need a bit more (up to perhaps
+16 more bytes).
+

+

+If the above command is given when PCRE is compiled to use the heap instead of
+the stack for recursion, the value that is output is the size of each block
+that is obtained from the heap.
+

+

+Changing stack size in Unix-like systems
+

+

+In Unix-like environments, there is not often a problem with the stack unless
+very long strings are involved, though the default limit on stack size varies
+from system to system. Values from 8Mb to 64Mb are common. You can find your
+default limit by running the command:
+
+  ulimit -s
+

+Unfortunately, the effect of running out of stack is often SIGSEGV, though
+sometimes a more explicit error message is given. You can normally increase the
+limit on stack size by code such as this:
+
+  struct rlimit rlim;
+  getrlimit(RLIMIT_STACK, &rlim);
+  rlim.rlim_cur = 100*1024*1024;
+  setrlimit(RLIMIT_STACK, &rlim);
+

+This reads the current limits (soft and hard) using getrlimit(), then
+attempts to increase the soft limit to 100Mb using setrlimit(). You must
+do this before calling pcre[16|32]_exec().
+

+

+Changing stack size in Mac OS X
+

+

+Using setrlimit(), as described above, should also work on Mac OS X. It
+is also possible to set a stack size when linking a program. There is a
+discussion about stack sizes in Mac OS X at this web site:
+http://developer.apple.com/qa/qa2005/qa1419.html.
+

+

+AUTHOR
+

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+

+REVISION
+

+

+Last updated: 24 June 2012
+

+Copyright © 1997-2012 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcresyntax.html b/doc/html/pcresyntax.html
new file mode 100644
index 0000000..89f3573
--- /dev/null
+++ b/doc/html/pcresyntax.html
@@ -0,0 +1,538 @@
+
+
+pcresyntax specification
+
+
+
pcresyntax man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+
PCRE REGULAR EXPRESSION SYNTAX SUMMARY

+

+The full syntax and semantics of the regular expressions that are supported by
+PCRE are described in the
+pcrepattern
+documentation. This document contains a quick-reference summary of the syntax.
+

+
QUOTING

+

+
+  \x         where x is non-alphanumeric is a literal x
+  \Q...\E    treat enclosed characters as literal
+

+

+
CHARACTERS

+

+
+  \a         alarm, that is, the BEL character (hex 07)
+  \cx        "control-x", where x is any ASCII character
+  \e         escape (hex 1B)
+  \f         form feed (hex 0C)
+  \n         newline (hex 0A)
+  \r         carriage return (hex 0D)
+  \t         tab (hex 09)
+  \0dd       character with octal code 0dd
+  \ddd       character with octal code ddd, or backreference
+  \o{ddd..}  character with octal code ddd..
+  \xhh       character with hex code hh
+  \x{hhh..}  character with hex code hhh..
+

+Note that \0dd is always an octal code, and that \8 and \9 are the literal
+characters "8" and "9".
+

+
CHARACTER TYPES

+

+
+  .          any character except newline;
+               in dotall mode, any character whatsoever
+  \C         one data unit, even in UTF mode (best avoided)
+  \d         a decimal digit
+  \D         a character that is not a decimal digit
+  \h         a horizontal white space character
+  \H         a character that is not a horizontal white space character
+  \N         a character that is not a newline
+  \p{xx}     a character with the xx property
+  \P{xx}     a character without the xx property
+  \R         a newline sequence
+  \s         a white space character
+  \S         a character that is not a white space character
+  \v         a vertical white space character
+  \V         a character that is not a vertical white space character
+  \w         a "word" character
+  \W         a "non-word" character
+  \X         a Unicode extended grapheme cluster
+

+By default, \d, \s, and \w match only ASCII characters, even in UTF-8 mode
+or in the 16- bit and 32-bit libraries. However, if locale-specific matching is
+happening, \s and \w may also match characters with code points in the range
+128-255. If the PCRE_UCP option is set, the behaviour of these escape sequences
+is changed to use Unicode properties and they match many more characters.
+

+
GENERAL CATEGORY PROPERTIES FOR \p and \P

+

+
+  C          Other
+  Cc         Control
+  Cf         Format
+  Cn         Unassigned
+  Co         Private use
+  Cs         Surrogate
+
+  L          Letter
+  Ll         Lower case letter
+  Lm         Modifier letter
+  Lo         Other letter
+  Lt         Title case letter
+  Lu         Upper case letter
+  L&         Ll, Lu, or Lt
+
+  M          Mark
+  Mc         Spacing mark
+  Me         Enclosing mark
+  Mn         Non-spacing mark
+
+  N          Number
+  Nd         Decimal number
+  Nl         Letter number
+  No         Other number
+
+  P          Punctuation
+  Pc         Connector punctuation
+  Pd         Dash punctuation
+  Pe         Close punctuation
+  Pf         Final punctuation
+  Pi         Initial punctuation
+  Po         Other punctuation
+  Ps         Open punctuation
+
+  S          Symbol
+  Sc         Currency symbol
+  Sk         Modifier symbol
+  Sm         Mathematical symbol
+  So         Other symbol
+
+  Z          Separator
+  Zl         Line separator
+  Zp         Paragraph separator
+  Zs         Space separator
+

+

+
PCRE SPECIAL CATEGORY PROPERTIES FOR \p and \P

+

+
+  Xan        Alphanumeric: union of properties L and N
+  Xps        POSIX space: property Z or tab, NL, VT, FF, CR
+  Xsp        Perl space: property Z or tab, NL, VT, FF, CR
+  Xuc        Univerally-named character: one that can be
+               represented by a Universal Character Name
+  Xwd        Perl word: property Xan or underscore
+

+Perl and POSIX space are now the same. Perl added VT to its space character set
+at release 5.18 and PCRE changed at release 8.34.
+

+
SCRIPT NAMES FOR \p AND \P

+

+Arabic,
+Armenian,
+Avestan,
+Balinese,
+Bamum,
+Batak,
+Bengali,
+Bopomofo,
+Brahmi,
+Braille,
+Buginese,
+Buhid,
+Canadian_Aboriginal,
+Carian,
+Chakma,
+Cham,
+Cherokee,
+Common,
+Coptic,
+Cuneiform,
+Cypriot,
+Cyrillic,
+Deseret,
+Devanagari,
+Egyptian_Hieroglyphs,
+Ethiopic,
+Georgian,
+Glagolitic,
+Gothic,
+Greek,
+Gujarati,
+Gurmukhi,
+Han,
+Hangul,
+Hanunoo,
+Hebrew,
+Hiragana,
+Imperial_Aramaic,
+Inherited,
+Inscriptional_Pahlavi,
+Inscriptional_Parthian,
+Javanese,
+Kaithi,
+Kannada,
+Katakana,
+Kayah_Li,
+Kharoshthi,
+Khmer,
+Lao,
+Latin,
+Lepcha,
+Limbu,
+Linear_B,
+Lisu,
+Lycian,
+Lydian,
+Malayalam,
+Mandaic,
+Meetei_Mayek,
+Meroitic_Cursive,
+Meroitic_Hieroglyphs,
+Miao,
+Mongolian,
+Myanmar,
+New_Tai_Lue,
+Nko,
+Ogham,
+Old_Italic,
+Old_Persian,
+Old_South_Arabian,
+Old_Turkic,
+Ol_Chiki,
+Oriya,
+Osmanya,
+Phags_Pa,
+Phoenician,
+Rejang,
+Runic,
+Samaritan,
+Saurashtra,
+Sharada,
+Shavian,
+Sinhala,
+Sora_Sompeng,
+Sundanese,
+Syloti_Nagri,
+Syriac,
+Tagalog,
+Tagbanwa,
+Tai_Le,
+Tai_Tham,
+Tai_Viet,
+Takri,
+Tamil,
+Telugu,
+Thaana,
+Thai,
+Tibetan,
+Tifinagh,
+Ugaritic,
+Vai,
+Yi.
+

+
CHARACTER CLASSES

+

+
+  [...]       positive character class
+  [^...]      negative character class
+  [x-y]       range (can be used for hex characters)
+  [[:xxx:]]   positive POSIX named set
+  [[:^xxx:]]  negative POSIX named set
+
+  alnum       alphanumeric
+  alpha       alphabetic
+  ascii       0-127
+  blank       space or tab
+  cntrl       control character
+  digit       decimal digit
+  graph       printing, excluding space
+  lower       lower case letter
+  print       printing, including space
+  punct       printing, excluding alphanumeric
+  space       white space
+  upper       upper case letter
+  word        same as \w
+  xdigit      hexadecimal digit
+

+In PCRE, POSIX character set names recognize only ASCII characters by default,
+but some of them use Unicode properties if PCRE_UCP is set. You can use
+\Q...\E inside a character class.
+

+
QUANTIFIERS

+

+
+  ?           0 or 1, greedy
+  ?+          0 or 1, possessive
+  ??          0 or 1, lazy
+  *           0 or more, greedy
+  *+          0 or more, possessive
+  *?          0 or more, lazy
+  +           1 or more, greedy
+  ++          1 or more, possessive
+  +?          1 or more, lazy
+  {n}         exactly n
+  {n,m}       at least n, no more than m, greedy
+  {n,m}+      at least n, no more than m, possessive
+  {n,m}?      at least n, no more than m, lazy
+  {n,}        n or more, greedy
+  {n,}+       n or more, possessive
+  {n,}?       n or more, lazy
+

+

+
ANCHORS AND SIMPLE ASSERTIONS

+

+
+  \b          word boundary
+  \B          not a word boundary
+  ^           start of subject
+               also after internal newline in multiline mode
+  \A          start of subject
+  $           end of subject
+               also before newline at end of subject
+               also before internal newline in multiline mode
+  \Z          end of subject
+               also before newline at end of subject
+  \z          end of subject
+  \G          first matching position in subject
+

+

+
MATCH POINT RESET

+

+
+  \K          reset start of match
+

+\K is honoured in positive assertions, but ignored in negative ones.
+

+
ALTERNATION

+

+
+  expr|expr|expr...
+

+

+
CAPTURING

+

+
+  (...)           capturing group
+  (?<name>...)    named capturing group (Perl)
+  (?'name'...)    named capturing group (Perl)
+  (?P<name>...)   named capturing group (Python)
+  (?:...)         non-capturing group
+  (?|...)         non-capturing group; reset group numbers for
+                   capturing groups in each alternative
+

+

+
ATOMIC GROUPS

+

+
+  (?>...)         atomic, non-capturing group
+

+

+
COMMENT

+

+
+  (?#....)        comment (not nestable)
+

+

+
OPTION SETTING

+

+
+  (?i)            caseless
+  (?J)            allow duplicate names
+  (?m)            multiline
+  (?s)            single line (dotall)
+  (?U)            default ungreedy (lazy)
+  (?x)            extended (ignore white space)
+  (?-...)         unset option(s)
+

+The following are recognized only at the very start of a pattern or after one
+of the newline or \R options with similar syntax. More than one of them may
+appear.
+
+  (*LIMIT_MATCH=d) set the match limit to d (decimal number)
+  (*LIMIT_RECURSION=d) set the recursion limit to d (decimal number)
+  (*NO_AUTO_POSSESS) no auto-possessification (PCRE_NO_AUTO_POSSESS)
+  (*NO_START_OPT) no start-match optimization (PCRE_NO_START_OPTIMIZE)
+  (*UTF8)         set UTF-8 mode: 8-bit library (PCRE_UTF8)
+  (*UTF16)        set UTF-16 mode: 16-bit library (PCRE_UTF16)
+  (*UTF32)        set UTF-32 mode: 32-bit library (PCRE_UTF32)
+  (*UTF)          set appropriate UTF mode for the library in use
+  (*UCP)          set PCRE_UCP (use Unicode properties for \d etc)
+

+Note that LIMIT_MATCH and LIMIT_RECURSION can only reduce the value of the
+limits set by the caller of pcre_exec(), not increase them.
+

+
NEWLINE CONVENTION

+

+These are recognized only at the very start of the pattern or after option
+settings with a similar syntax.
+
+  (*CR)           carriage return only
+  (*LF)           linefeed only
+  (*CRLF)         carriage return followed by linefeed
+  (*ANYCRLF)      all three of the above
+  (*ANY)          any Unicode newline sequence
+

+

+
WHAT \R MATCHES

+

+These are recognized only at the very start of the pattern or after option
+setting with a similar syntax.
+
+  (*BSR_ANYCRLF)  CR, LF, or CRLF
+  (*BSR_UNICODE)  any Unicode newline sequence
+

+

+
LOOKAHEAD AND LOOKBEHIND ASSERTIONS

+

+
+  (?=...)         positive look ahead
+  (?!...)         negative look ahead
+  (?<=...)        positive look behind
+  (?<!...)        negative look behind
+

+Each top-level branch of a look behind must be of a fixed length.
+

+
BACKREFERENCES

+

+
+  \n              reference by number (can be ambiguous)
+  \gn             reference by number
+  \g{n}           reference by number
+  \g{-n}          relative reference by number
+  \k<name>        reference by name (Perl)
+  \k'name'        reference by name (Perl)
+  \g{name}        reference by name (Perl)
+  \k{name}        reference by name (.NET)
+  (?P=name)       reference by name (Python)
+

+

+
SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)

+

+
+  (?R)            recurse whole pattern
+  (?n)            call subpattern by absolute number
+  (?+n)           call subpattern by relative number
+  (?-n)           call subpattern by relative number
+  (?&name)        call subpattern by name (Perl)
+  (?P>name)       call subpattern by name (Python)
+  \g<name>        call subpattern by name (Oniguruma)
+  \g'name'        call subpattern by name (Oniguruma)
+  \g<n>           call subpattern by absolute number (Oniguruma)
+  \g'n'           call subpattern by absolute number (Oniguruma)
+  \g<+n>          call subpattern by relative number (PCRE extension)
+  \g'+n'          call subpattern by relative number (PCRE extension)
+  \g<-n>          call subpattern by relative number (PCRE extension)
+  \g'-n'          call subpattern by relative number (PCRE extension)
+

+

+
CONDITIONAL PATTERNS

+

+
+  (?(condition)yes-pattern)
+  (?(condition)yes-pattern|no-pattern)
+
+  (?(n)...        absolute reference condition
+  (?(+n)...       relative reference condition
+  (?(-n)...       relative reference condition
+  (?(<name>)...   named reference condition (Perl)
+  (?('name')...   named reference condition (Perl)
+  (?(name)...     named reference condition (PCRE)
+  (?(R)...        overall recursion condition
+  (?(Rn)...       specific group recursion condition
+  (?(R&name)...   specific recursion condition
+  (?(DEFINE)...   define subpattern for reference
+  (?(assert)...   assertion condition
+

+

+
BACKTRACKING CONTROL

+

+The following act immediately they are reached:
+
+  (*ACCEPT)       force successful match
+  (*FAIL)         force backtrack; synonym (*F)
+  (*MARK:NAME)    set name to be passed back; synonym (*:NAME)
+

+The following act only when a subsequent match failure causes a backtrack to
+reach them. They all force a match failure, but they differ in what happens
+afterwards. Those that advance the start-of-match point do so only if the
+pattern is not anchored.
+
+  (*COMMIT)       overall failure, no advance of starting point
+  (*PRUNE)        advance to next starting character
+  (*PRUNE:NAME)   equivalent to (*MARK:NAME)(*PRUNE)
+  (*SKIP)         advance to current matching position
+  (*SKIP:NAME)    advance to position corresponding to an earlier
+                  (*MARK:NAME); if not found, the (*SKIP) is ignored
+  (*THEN)         local failure, backtrack to next alternation
+  (*THEN:NAME)    equivalent to (*MARK:NAME)(*THEN)
+

+

+
CALLOUTS

+

+
+  (?C)      callout
+  (?Cn)     callout with data n
+

+

+
SEE ALSO

+

+pcrepattern(3), pcreapi(3), pcrecallout(3),
+pcrematching(3), pcre(3).
+

+
AUTHOR

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+
REVISION

+

+Last updated: 08 January 2014
+

+Copyright © 1997-2014 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcretest.html b/doc/html/pcretest.html
new file mode 100644
index 0000000..839fabf
--- /dev/null
+++ b/doc/html/pcretest.html
@@ -0,0 +1,1158 @@
+
+
+pcretest specification
+
+
+
pcretest man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+
SYNOPSIS

+

+pcretest [options] [input file [output file]]
+

+

+pcretest was written as a test program for the PCRE regular expression
+library itself, but it can also be used for experimenting with regular
+expressions. This document describes the features of the test program; for
+details of the regular expressions themselves, see the
+pcrepattern
+documentation. For details of the PCRE library function calls and their
+options, see the
+pcreapi
+,
+pcre16
+and
+pcre32
+documentation.
+

+

+The input for pcretest is a sequence of regular expression patterns and
+strings to be matched, as described below. The output shows the result of each
+match. Options on the command line and the patterns control PCRE options and
+exactly what is output.
+

+

+As PCRE has evolved, it has acquired many different features, and as a result,
+pcretest now has rather a lot of obscure options for testing every
+possible feature. Some of these options are specifically designed for use in
+conjunction with the test script and data files that are distributed as part of
+PCRE, and are unlikely to be of use otherwise. They are all documented here,
+but without much justification.
+

+
INPUT DATA FORMAT

+

+Input to pcretest is processed line by line, either by calling the C
+library's fgets() function, or via the libreadline library (see
+below). In Unix-like environments, fgets() treats any bytes other than
+newline as data characters. However, in some Windows environments character 26
+(hex 1A) causes an immediate end of file, and no further data is read. For
+maximum portability, therefore, it is safest to use only ASCII characters in
+pcretest input files.
+

+
PCRE's 8-BIT, 16-BIT AND 32-BIT LIBRARIES

+

+From release 8.30, two separate PCRE libraries can be built. The original one
+supports 8-bit character strings, whereas the newer 16-bit library supports
+character strings encoded in 16-bit units. From release 8.32, a third library
+can be built, supporting character strings encoded in 32-bit units. The
+pcretest program can be used to test all three libraries. However, it is
+itself still an 8-bit program, reading 8-bit input and writing 8-bit output.
+When testing the 16-bit or 32-bit library, the patterns and data strings are
+converted to 16- or 32-bit format before being passed to the PCRE library
+functions. Results are converted to 8-bit for output.
+

+

+References to functions and structures of the form pcre[16|32]_xx below
+mean "pcre_xx when using the 8-bit library, pcre16_xx when using
+the 16-bit library, or pcre32_xx when using the 32-bit library".
+

+
COMMAND LINE OPTIONS

+

+-8
+If both the 8-bit library has been built, this option causes the 8-bit library
+to be used (which is the default); if the 8-bit library has not been built,
+this option causes an error.
+

+

+-16
+If both the 8-bit or the 32-bit, and the 16-bit libraries have been built, this
+option causes the 16-bit library to be used. If only the 16-bit library has been
+built, this is the default (so has no effect). If only the 8-bit or the 32-bit
+library has been built, this option causes an error.
+

+

+-32
+If both the 8-bit or the 16-bit, and the 32-bit libraries have been built, this
+option causes the 32-bit library to be used. If only the 32-bit library has been
+built, this is the default (so has no effect). If only the 8-bit or the 16-bit
+library has been built, this option causes an error.
+

+

+-b
+Behave as if each pattern has the /B (show byte code) modifier; the
+internal form is output after compilation.
+

+

+-C
+Output the version number of the PCRE library, and all available information
+about the optional features that are included, and then exit with zero exit
+code. All other options are ignored.
+

+

+-C option
+Output information about a specific build-time option, then exit. This
+functionality is intended for use in scripts such as RunTest. The
+following options output the value and set the exit code as indicated:
+
+  ebcdic-nl  the code for LF (= NL) in an EBCDIC environment:
+               0x15 or 0x25
+               0 if used in an ASCII environment
+               exit code is always 0
+  linksize   the configured internal link size (2, 3, or 4)
+               exit code is set to the link size
+  newline    the default newline setting:
+               CR, LF, CRLF, ANYCRLF, or ANY
+               exit code is always 0
+  bsr        the default setting for what \R matches:
+               ANYCRLF or ANY
+               exit code is always 0
+

+The following options output 1 for true or 0 for false, and set the exit code
+to the same value:
+
+  ebcdic     compiled for an EBCDIC environment
+  jit        just-in-time support is available
+  pcre16     the 16-bit library was built
+  pcre32     the 32-bit library was built
+  pcre8      the 8-bit library was built
+  ucp        Unicode property support is available
+  utf        UTF-8 and/or UTF-16 and/or UTF-32 support
+               is available
+

+If an unknown option is given, an error message is output; the exit code is 0.
+

+

+-d
+Behave as if each pattern has the /D (debug) modifier; the internal
+form and information about the compiled pattern is output after compilation;
+-d is equivalent to -b -i.
+

+

+-dfa
+Behave as if each data line contains the \D escape sequence; this causes the
+alternative matching function, pcre[16|32]_dfa_exec(), to be used instead
+of the standard pcre[16|32]_exec() function (more detail is given below).
+

+

+-help
+Output a brief summary these options and then exit.
+

+

+-i
+Behave as if each pattern has the /I modifier; information about the
+compiled pattern is given after compilation.
+

+

+-M
+Behave as if each data line contains the \M escape sequence; this causes
+PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
+calling pcre[16|32]_exec() repeatedly with different limits.
+

+

+-m
+Output the size of each compiled pattern after it has been compiled. This is
+equivalent to adding /M to each regular expression. The size is given in
+bytes for both libraries.
+

+

+-O
+Behave as if each pattern has the /O modifier, that is disable
+auto-possessification for all patterns.
+

+

+-o osize
+Set the number of elements in the output vector that is used when calling
+pcre[16|32]_exec() or pcre[16|32]_dfa_exec() to be osize. The
+default value is 45, which is enough for 14 capturing subexpressions for
+pcre[16|32]_exec() or 22 different matches for
+pcre[16|32]_dfa_exec().
+The vector size can be changed for individual matching calls by including \O
+in the data line (see below).
+

+

+-p
+Behave as if each pattern has the /P modifier; the POSIX wrapper API is
+used to call PCRE. None of the other options has any effect when -p is
+set. This option can be used only with the 8-bit library.
+

+

+-q
+Do not output the version number of pcretest at the start of execution.
+

+

+-S size
+On Unix-like systems, set the size of the run-time stack to size
+megabytes.
+

+

+-s or -s+
+Behave as if each pattern has the /S modifier; in other words, force each
+pattern to be studied. If -s+ is used, all the JIT compile options are
+passed to pcre[16|32]_study(), causing just-in-time optimization to be set
+up if it is available, for both full and partial matching. Specific JIT compile
+options can be selected by following -s+ with a digit in the range 1 to
+7, which selects the JIT compile modes as follows:
+
+  1  normal match only
+  2  soft partial match only
+  3  normal match and soft partial match
+  4  hard partial match only
+  6  soft and hard partial match
+  7  all three modes (default)
+

+If -s++ is used instead of -s+ (with or without a following digit),
+the text "(JIT)" is added to the first output line after a match or no match
+when JIT-compiled code was actually used.
+

+

+Note that there are pattern options that can override -s, either
+specifying no studying at all, or suppressing JIT compilation.
+

+

+If the /I or /D option is present on a pattern (requesting output
+about the compiled pattern), information about the result of studying is not
+included when studying is caused only by -s and neither -i nor
+-d is present on the command line. This behaviour means that the output
+from tests that are run with and without -s should be identical, except
+when options that output information about the actual running of a match are
+set.
+

+

+The -M, -t, and -tm options, which give information about
+resources used, are likely to produce different output with and without
+-s. Output may also differ if the /C option is present on an
+individual pattern. This uses callouts to trace the the matching process, and
+this may be different between studied and non-studied patterns. If the pattern
+contains (*MARK) items there may also be differences, for the same reason. The
+-s command line option can be overridden for specific patterns that
+should never be studied (see the /S pattern modifier below).
+

+

+-t
+Run each compile, study, and match many times with a timer, and output the
+resulting times per compile, study, or match (in milliseconds). Do not set
+-m with -t, because you will then get the size output a zillion
+times, and the timing will be distorted. You can control the number of
+iterations that are used for timing by following -t with a number (as a
+separate item on the command line). For example, "-t 1000" iterates 1000 times.
+The default is to iterate 500000 times.
+

+

+-tm
+This is like -t except that it times only the matching phase, not the
+compile or study phases.
+

+

+-T -TM
+These behave like -t and -tm, but in addition, at the end of a run,
+the total times for all compiles, studies, and matches are output.
+

+
DESCRIPTION

+

+If pcretest is given two filename arguments, it reads from the first and
+writes to the second. If it is given only one filename argument, it reads from
+that file and writes to stdout. Otherwise, it reads from stdin and writes to
+stdout, and prompts for each line of input, using "re>" to prompt for regular
+expressions, and "data>" to prompt for data lines.
+

+

+When pcretest is built, a configuration option can specify that it should
+be linked with the libreadline library. When this is done, if the input
+is from a terminal, it is read using the readline() function. This
+provides line-editing and history facilities. The output from the -help
+option states whether or not readline() will be used.
+

+

+The program handles any number of sets of input on a single input file. Each
+set starts with a regular expression, and continues with any number of data
+lines to be matched against that pattern.
+

+

+Each data line is matched separately and independently. If you want to do
+multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
+etc., depending on the newline setting) in a single line of input to encode the
+newline sequences. There is no limit on the length of data lines; the input
+buffer is automatically extended if it is too small.
+

+

+An empty line signals the end of the data lines, at which point a new regular
+expression is read. The regular expressions are given enclosed in any
+non-alphanumeric delimiters other than backslash, for example:
+
+  /(a|bc)x+yz/
+

+White space before the initial delimiter is ignored. A regular expression may
+be continued over several input lines, in which case the newline characters are
+included within it. It is possible to include the delimiter within the pattern
+by escaping it, for example
+
+  /abc\/def/
+

+If you do so, the escape and the delimiter form part of the pattern, but since
+delimiters are always non-alphanumeric, this does not affect its interpretation.
+If the terminating delimiter is immediately followed by a backslash, for
+example,
+
+  /abc/\
+

+then a backslash is added to the end of the pattern. This is done to provide a
+way of testing the error condition that arises if a pattern finishes with a
+backslash, because
+
+  /abc\/
+

+is interpreted as the first line of a pattern that starts with "abc/", causing
+pcretest to read the next line as a continuation of the regular expression.
+

+
PATTERN MODIFIERS

+

+A pattern may be followed by any number of modifiers, which are mostly single
+characters, though some of these can be qualified by further characters.
+Following Perl usage, these are referred to below as, for example, "the
+/i modifier", even though the delimiter of the pattern need not always be
+a slash, and no slash is used when writing modifiers. White space may appear
+between the final pattern delimiter and the first modifier, and between the
+modifiers themselves. For reference, here is a complete list of modifiers. They
+fall into several groups that are described in detail in the following
+sections.
+
+  /8              set UTF mode
+  /9              set PCRE_NEVER_UTF (locks out UTF mode)
+  /?              disable UTF validity check
+  /+              show remainder of subject after match
+  /=              show all captures (not just those that are set)
+
+  /A              set PCRE_ANCHORED
+  /B              show compiled code
+  /C              set PCRE_AUTO_CALLOUT
+  /D              same as /B plus /I
+  /E              set PCRE_DOLLAR_ENDONLY
+  /F              flip byte order in compiled pattern
+  /f              set PCRE_FIRSTLINE
+  /G              find all matches (shorten string)
+  /g              find all matches (use startoffset)
+  /I              show information about pattern
+  /i              set PCRE_CASELESS
+  /J              set PCRE_DUPNAMES
+  /K              show backtracking control names
+  /L              set locale
+  /M              show compiled memory size
+  /m              set PCRE_MULTILINE
+  /N              set PCRE_NO_AUTO_CAPTURE
+  /O              set PCRE_NO_AUTO_POSSESS
+  /P              use the POSIX wrapper
+  /Q              test external stack check function
+  /S              study the pattern after compilation
+  /s              set PCRE_DOTALL
+  /T              select character tables
+  /U              set PCRE_UNGREEDY
+  /W              set PCRE_UCP
+  /X              set PCRE_EXTRA
+  /x              set PCRE_EXTENDED
+  /Y              set PCRE_NO_START_OPTIMIZE
+  /Z              don't show lengths in /B output
+
+  /<any>          set PCRE_NEWLINE_ANY
+  /<anycrlf>      set PCRE_NEWLINE_ANYCRLF
+  /<cr>           set PCRE_NEWLINE_CR
+  /<crlf>         set PCRE_NEWLINE_CRLF
+  /<lf>           set PCRE_NEWLINE_LF
+  /<bsr_anycrlf>  set PCRE_BSR_ANYCRLF
+  /<bsr_unicode>  set PCRE_BSR_UNICODE
+  /<JS>           set PCRE_JAVASCRIPT_COMPAT
+
+

+

+

+Perl-compatible modifiers
+

+

+The /i, /m, /s, and /x modifiers set the PCRE_CASELESS,
+PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
+pcre[16|32]_compile() is called. These four modifier letters have the same
+effect as they do in Perl. For example:
+
+  /caseless/i
+
+

+

+

+Modifiers for other PCRE options
+

+

+The following table shows additional modifiers for setting PCRE compile-time
+options that do not correspond to anything in Perl:
+
+  /8              PCRE_UTF8           ) when using the 8-bit
+  /?              PCRE_NO_UTF8_CHECK  )   library
+
+  /8              PCRE_UTF16          ) when using the 16-bit
+  /?              PCRE_NO_UTF16_CHECK )   library
+
+  /8              PCRE_UTF32          ) when using the 32-bit
+  /?              PCRE_NO_UTF32_CHECK )   library
+
+  /9              PCRE_NEVER_UTF
+  /A              PCRE_ANCHORED
+  /C              PCRE_AUTO_CALLOUT
+  /E              PCRE_DOLLAR_ENDONLY
+  /f              PCRE_FIRSTLINE
+  /J              PCRE_DUPNAMES
+  /N              PCRE_NO_AUTO_CAPTURE
+  /O              PCRE_NO_AUTO_POSSESS
+  /U              PCRE_UNGREEDY
+  /W              PCRE_UCP
+  /X              PCRE_EXTRA
+  /Y              PCRE_NO_START_OPTIMIZE
+  /<any>          PCRE_NEWLINE_ANY
+  /<anycrlf>      PCRE_NEWLINE_ANYCRLF
+  /<cr>           PCRE_NEWLINE_CR
+  /<crlf>         PCRE_NEWLINE_CRLF
+  /<lf>           PCRE_NEWLINE_LF
+  /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
+  /<bsr_unicode>  PCRE_BSR_UNICODE
+  /<JS>           PCRE_JAVASCRIPT_COMPAT
+

+The modifiers that are enclosed in angle brackets are literal strings as shown,
+including the angle brackets, but the letters within can be in either case.
+This example sets multiline matching with CRLF as the line ending sequence:
+
+  /^abc/m<CRLF>
+

+As well as turning on the PCRE_UTF8/16/32 option, the /8 modifier causes
+all non-printing characters in output strings to be printed using the
+\x{hh...} notation. Otherwise, those less than 0x100 are output in hex without
+the curly brackets.
+

+

+Full details of the PCRE options are given in the
+pcreapi
+documentation.
+

+

+Finding all matches in a string
+

+

+Searching for all possible matches within each subject string can be requested
+by the /g or /G modifier. After finding a match, PCRE is called
+again to search the remainder of the subject string. The difference between
+/g and /G is that the former uses the startoffset argument to
+pcre[16|32]_exec() to start searching at a new point within the entire
+string (which is in effect what Perl does), whereas the latter passes over a
+shortened substring. This makes a difference to the matching process if the
+pattern begins with a lookbehind assertion (including \b or \B).
+

+

+If any call to pcre[16|32]_exec() in a /g or /G sequence matches
+an empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
+PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
+same point. If this second match fails, the start offset is advanced, and the
+normal match is retried. This imitates the way Perl handles such cases when
+using the /g modifier or the split() function. Normally, the start
+offset is advanced by one character, but if the newline convention recognizes
+CRLF as a newline, and the current character is CR followed by LF, an advance
+of two is used.
+

+

+Other modifiers
+

+

+There are yet more modifiers for controlling the way pcretest
+operates.
+

+

+The /+ modifier requests that as well as outputting the substring that
+matched the entire pattern, pcretest should in addition output the
+remainder of the subject string. This is useful for tests where the subject
+contains multiple copies of the same substring. If the + modifier appears
+twice, the same action is taken for captured substrings. In each case the
+remainder is output on the following line with a plus character following the
+capture number. Note that this modifier must not immediately follow the /S
+modifier because /S+ and /S++ have other meanings.
+

+

+The /= modifier requests that the values of all potential captured
+parentheses be output after a match. By default, only those up to the highest
+one actually used in the match are output (corresponding to the return code
+from pcre[16|32]_exec()). Values in the offsets vector corresponding to
+higher numbers should be set to -1, and these are output as "<unset>". This
+modifier gives a way of checking that this is happening.
+

+

+The /B modifier is a debugging feature. It requests that pcretest
+output a representation of the compiled code after compilation. Normally this
+information contains length and offset values; however, if /Z is also
+present, this data is replaced by spaces. This is a special feature for use in
+the automatic test scripts; it ensures that the same output is generated for
+different internal link sizes.
+

+

+The /D modifier is a PCRE debugging feature, and is equivalent to
+/BI, that is, both the /B and the /I modifiers.
+

+

+The /F modifier causes pcretest to flip the byte order of the
+2-byte and 4-byte fields in the compiled pattern. This facility is for testing
+the feature in PCRE that allows it to execute patterns that were compiled on a
+host with a different endianness. This feature is not available when the POSIX
+interface to PCRE is being used, that is, when the /P pattern modifier is
+specified. See also the section about saving and reloading compiled patterns
+below.
+

+

+The /I modifier requests that pcretest output information about the
+compiled pattern (whether it is anchored, has a fixed first character, and
+so on). It does this by calling pcre[16|32]_fullinfo() after compiling a
+pattern. If the pattern is studied, the results of that are also output. In
+this output, the word "char" means a non-UTF character, that is, the value of a
+single data item (8-bit, 16-bit, or 32-bit, depending on the library that is
+being tested).
+

+

+The /K modifier requests pcretest to show names from backtracking
+control verbs that are returned from calls to pcre[16|32]_exec(). It causes
+pcretest to create a pcre[16|32]_extra block if one has not already
+been created by a call to pcre[16|32]_study(), and to set the
+PCRE_EXTRA_MARK flag and the mark field within it, every time that
+pcre[16|32]_exec() is called. If the variable that the mark field
+points to is non-NULL for a match, non-match, or partial match, pcretest
+prints the string to which it points. For a match, this is shown on a line by
+itself, tagged with "MK:". For a non-match it is added to the message.
+

+

+The /L modifier must be followed directly by the name of a locale, for
+example,
+
+  /pattern/Lfr_FR
+

+For this reason, it must be the last modifier. The given locale is set,
+pcre[16|32]_maketables() is called to build a set of character tables for
+the locale, and this is then passed to pcre[16|32]_compile() when compiling
+the regular expression. Without an /L (or /T) modifier, NULL is
+passed as the tables pointer; that is, /L applies only to the expression
+on which it appears.
+

+

+The /M modifier causes the size in bytes of the memory block used to hold
+the compiled pattern to be output. This does not include the size of the
+pcre[16|32] block; it is just the actual compiled data. If the pattern is
+successfully studied with the PCRE_STUDY_JIT_COMPILE option, the size of the
+JIT compiled code is also output.
+

+

+The /Q modifier is used to test the use of pcre_stack_guard. It
+must be followed by '0' or '1', specifying the return code to be given from an
+external function that is passed to PCRE and used for stack checking during
+compilation (see the
+pcreapi
+documentation for details).
+

+

+The /S modifier causes pcre[16|32]_study() to be called after the
+expression has been compiled, and the results used when the expression is
+matched. There are a number of qualifying characters that may follow /S.
+They may appear in any order.
+

+

+If /S is followed by an exclamation mark, pcre[16|32]_study() is
+called with the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a
+pcre_extra block, even when studying discovers no useful information.
+

+

+If /S is followed by a second S character, it suppresses studying, even
+if it was requested externally by the -s command line option. This makes
+it possible to specify that certain patterns are always studied, and others are
+never studied, independently of -s. This feature is used in the test
+files in a few cases where the output is different when the pattern is studied.
+

+

+If the /S modifier is followed by a + character, the call to
+pcre[16|32]_study() is made with all the JIT study options, requesting
+just-in-time optimization support if it is available, for both normal and
+partial matching. If you want to restrict the JIT compiling modes, you can
+follow /S+ with a digit in the range 1 to 7:
+
+  1  normal match only
+  2  soft partial match only
+  3  normal match and soft partial match
+  4  hard partial match only
+  6  soft and hard partial match
+  7  all three modes (default)
+

+If /S++ is used instead of /S+ (with or without a following digit),
+the text "(JIT)" is added to the first output line after a match or no match
+when JIT-compiled code was actually used.
+

+

+Note that there is also an independent /+ modifier; it must not be given
+immediately after /S or /S+ because this will be misinterpreted.
+

+

+If JIT studying is successful, the compiled JIT code will automatically be used
+when pcre[16|32]_exec() is run, except when incompatible run-time options
+are specified. For more details, see the
+pcrejit
+documentation. See also the \J escape sequence below for a way of
+setting the size of the JIT stack.
+

+

+Finally, if /S is followed by a minus character, JIT compilation is
+suppressed, even if it was requested externally by the -s command line
+option. This makes it possible to specify that JIT is never to be used for
+certain patterns.
+

+

+The /T modifier must be followed by a single digit. It causes a specific
+set of built-in character tables to be passed to pcre[16|32]_compile(). It
+is used in the standard PCRE tests to check behaviour with different character
+tables. The digit specifies the tables as follows:
+
+  0   the default ASCII tables, as distributed in
+        pcre_chartables.c.dist
+  1   a set of tables defining ISO 8859 characters
+

+In table 1, some characters whose codes are greater than 128 are identified as
+letters, digits, spaces, etc.
+

+

+Using the POSIX wrapper API
+

+

+The /P modifier causes pcretest to call PCRE via the POSIX wrapper
+API rather than its native API. This supports only the 8-bit library. When
+/P is set, the following modifiers set options for the regcomp()
+function:
+
+  /i    REG_ICASE
+  /m    REG_NEWLINE
+  /N    REG_NOSUB
+  /s    REG_DOTALL     )
+  /U    REG_UNGREEDY   ) These options are not part of
+  /W    REG_UCP        )   the POSIX standard
+  /8    REG_UTF8       )
+

+The /+ modifier works as described above. All other modifiers are
+ignored.
+

+

+Locking out certain modifiers
+

+

+PCRE can be compiled with or without support for certain features such as
+UTF-8/16/32 or Unicode properties. Accordingly, the standard tests are split up
+into a number of different files that are selected for running depending on
+which features are available. When updating the tests, it is all too easy to
+put a new test into the wrong file by mistake; for example, to put a test that
+requires UTF support into a file that is used when it is not available. To help
+detect such mistakes as early as possible, there is a facility for locking out
+specific modifiers. If an input line for pcretest starts with the string
+"< forbid " the following sequence of characters is taken as a list of
+forbidden modifiers. For example, in the test files that must not use UTF or
+Unicode property support, this line appears:
+
+  < forbid 8W
+

+This locks out the /8 and /W modifiers. An immediate error is given if they are
+subsequently encountered. If the character string contains < but not >, all the
+multi-character modifiers that begin with < are locked out. Otherwise, such
+modifiers must be explicitly listed, for example:
+
+  < forbid <JS><cr>
+

+There must be a single space between < and "forbid" for this feature to be
+recognised. If there is not, the line is interpreted either as a request to
+re-load a pre-compiled pattern (see "SAVING AND RELOADING COMPILED PATTERNS"
+below) or, if there is a another < character, as a pattern that uses < as its
+delimiter.
+

+
DATA LINES

+

+Before each data line is passed to pcre[16|32]_exec(), leading and trailing
+white space is removed, and it is then scanned for \ escapes. Some of these
+are pretty esoteric features, intended for checking out some of the more
+complicated features of PCRE. If you are just testing "ordinary" regular
+expressions, you probably don't need any of these. The following escapes are
+recognized:
+
+  \a         alarm (BEL, \x07)
+  \b         backspace (\x08)
+  \e         escape (\x27)
+  \f         form feed (\x0c)
+  \n         newline (\x0a)
+  \qdd       set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
+  \r         carriage return (\x0d)
+  \t         tab (\x09)
+  \v         vertical tab (\x0b)
+  \nnn       octal character (up to 3 octal digits); always
+               a byte unless > 255 in UTF-8 or 16-bit or 32-bit mode
+  \o{dd...}  octal character (any number of octal digits}
+  \xhh       hexadecimal byte (up to 2 hex digits)
+  \x{hh...}  hexadecimal character (any number of hex digits)
+  \A         pass the PCRE_ANCHORED option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \B         pass the PCRE_NOTBOL option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \Cdd       call pcre[16|32]_copy_substring() for substring dd after a successful match (number less than 32)
+  \Cname     call pcre[16|32]_copy_named_substring() for substring "name" after a successful match (name termin-
+               ated by next non alphanumeric character)
+  \C+        show the current captured substrings at callout time
+  \C-        do not supply a callout function
+  \C!n       return 1 instead of 0 when callout number n is reached
+  \C!n!m     return 1 instead of 0 when callout number n is reached for the nth time
+  \C*n       pass the number n (may be negative) as callout data; this is used as the callout return value
+  \D         use the pcre[16|32]_dfa_exec() match function
+  \F         only shortest match for pcre[16|32]_dfa_exec()
+  \Gdd       call pcre[16|32]_get_substring() for substring dd after a successful match (number less than 32)
+  \Gname     call pcre[16|32]_get_named_substring() for substring "name" after a successful match (name termin-
+               ated by next non-alphanumeric character)
+  \Jdd       set up a JIT stack of dd kilobytes maximum (any number of digits)
+  \L         call pcre[16|32]_get_substringlist() after a successful match
+  \M         discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
+  \N         pass the PCRE_NOTEMPTY option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec(); if used twice, pass the
+               PCRE_NOTEMPTY_ATSTART option
+  \Odd       set the size of the output vector passed to pcre[16|32]_exec() to dd (any number of digits)
+  \P         pass the PCRE_PARTIAL_SOFT option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec(); if used twice, pass the
+               PCRE_PARTIAL_HARD option
+  \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
+  \R         pass the PCRE_DFA_RESTART option to pcre[16|32]_dfa_exec()
+  \S         output details of memory get/free calls during matching
+  \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \Z         pass the PCRE_NOTEOL option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \?         pass the PCRE_NO_UTF[8|16|32]_CHECK option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \>dd       start the match at offset dd (optional "-"; then any number of digits); this sets the startoffset
+               argument for pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \<cr>      pass the PCRE_NEWLINE_CR option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \<lf>      pass the PCRE_NEWLINE_LF option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+  \<any>     pass the PCRE_NEWLINE_ANY option to pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+

+The use of \x{hh...} is not dependent on the use of the /8 modifier on
+the pattern. It is recognized always. There may be any number of hexadecimal
+digits inside the braces; invalid values provoke error messages.
+

+

+Note that \xhh specifies one byte rather than one character in UTF-8 mode;
+this makes it possible to construct invalid UTF-8 sequences for testing
+purposes. On the other hand, \x{hh} is interpreted as a UTF-8 character in
+UTF-8 mode, generating more than one byte if the value is greater than 127.
+When testing the 8-bit library not in UTF-8 mode, \x{hh} generates one byte
+for values less than 256, and causes an error for greater values.
+

+

+In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
+possible to construct invalid UTF-16 sequences for testing purposes.
+

+

+In UTF-32 mode, all 4- to 8-digit \x{...} values are accepted. This makes it
+possible to construct invalid UTF-32 sequences for testing purposes.
+

+

+The escapes that specify line ending sequences are literal strings, exactly as
+shown. No more than one newline setting should be present in any data line.
+

+

+A backslash followed by anything else just escapes the anything else. If
+the very last character is a backslash, it is ignored. This gives a way of
+passing an empty line as data, since a real empty line terminates the data
+input.
+

+

+The \J escape provides a way of setting the maximum stack size that is
+used by the just-in-time optimization code. It is ignored if JIT optimization
+is not being used. Providing a stack that is larger than the default 32K is
+necessary only for very complicated patterns.
+

+

+If \M is present, pcretest calls pcre[16|32]_exec() several times,
+with different values in the match_limit and match_limit_recursion
+fields of the pcre[16|32]_extra data structure, until it finds the minimum
+numbers for each parameter that allow pcre[16|32]_exec() to complete without
+error. Because this is testing a specific feature of the normal interpretive
+pcre[16|32]_exec() execution, the use of any JIT optimization that might
+have been set up by the /S+ qualifier of -s+ option is disabled.
+

+

+The match_limit number is a measure of the amount of backtracking
+that takes place, and checking it out can be instructive. For most simple
+matches, the number is quite small, but for patterns with very large numbers of
+matching possibilities, it can become large very quickly with increasing length
+of subject string. The match_limit_recursion number is a measure of how
+much stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is
+needed to complete the match attempt.
+

+

+When \O is used, the value specified may be higher or lower than the size set
+by the -O command line option (or defaulted to 45); \O applies only to
+the call of pcre[16|32]_exec() for the line in which it appears.
+

+

+If the /P modifier was present on the pattern, causing the POSIX wrapper
+API to be used, the only option-setting sequences that have any effect are \B,
+\N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
+to be passed to regexec().
+

+
THE ALTERNATIVE MATCHING FUNCTION

+

+By default, pcretest uses the standard PCRE matching function,
+pcre[16|32]_exec() to match each data line. PCRE also supports an
+alternative matching function, pcre[16|32]_dfa_test(), which operates in a
+different way, and has some restrictions. The differences between the two
+functions are described in the
+pcrematching
+documentation.
+

+

+If a data line contains the \D escape sequence, or if the command line
+contains the -dfa option, the alternative matching function is used.
+This function finds all possible matches at a given point. If, however, the \F
+escape sequence is present in the data line, it stops after the first match is
+found. This is always the shortest possible match.
+

+
DEFAULT OUTPUT FROM PCRETEST

+

+This section describes the output when the normal matching function,
+pcre[16|32]_exec(), is being used.
+

+

+When a match succeeds, pcretest outputs the list of captured substrings
+that pcre[16|32]_exec() returns, starting with number 0 for the string that
+matched the whole pattern. Otherwise, it outputs "No match" when the return is
+PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
+substring when pcre[16|32]_exec() returns PCRE_ERROR_PARTIAL. (Note that
+this is the entire substring that was inspected during the partial match; it
+may include characters before the actual match start if a lookbehind assertion,
+\K, \b, or \B was involved.) For any other return, pcretest outputs
+the PCRE negative error number and a short descriptive phrase. If the error is
+a failed UTF string check, the offset of the start of the failing character and
+the reason code are also output, provided that the size of the output vector is
+at least two. Here is an example of an interactive pcretest run.
+
+  $ pcretest
+  PCRE version 8.13 2011-04-30
+
+    re> /^abc(\d+)/
+  data> abc123
+   0: abc123
+   1: 123
+  data> xyz
+  No match
+

+Unset capturing substrings that are not followed by one that is set are not
+returned by pcre[16|32]_exec(), and are not shown by pcretest. In the
+following example, there are two capturing substrings, but when the first data
+line is matched, the second, unset substring is not shown. An "internal" unset
+substring is shown as "<unset>", as for the second data line.
+
+    re> /(a)|(b)/
+  data> a
+   0: a
+   1: a
+  data> b
+   0: b
+   1: <unset>
+   2: b
+

+If the strings contain any non-printing characters, they are output as \xhh
+escapes if the value is less than 256 and UTF mode is not set. Otherwise they
+are output as \x{hh...} escapes. See below for the definition of non-printing
+characters. If the pattern has the /+ modifier, the output for substring
+0 is followed by the the rest of the subject string, identified by "0+" like
+this:
+
+    re> /cat/+
+  data> cataract
+   0: cat
+   0+ aract
+

+If the pattern has the /g or /G modifier, the results of successive
+matching attempts are output in sequence, like this:
+
+    re> /\Bi(\w\w)/g
+  data> Mississippi
+   0: iss
+   1: ss
+   0: iss
+   1: ss
+   0: ipp
+   1: pp
+

+"No match" is output only if the first match attempt fails. Here is an example
+of a failure message (the offset 4 that is specified by \>4 is past the end of
+the subject string):
+
+    re> /xyz/
+  data> xyz\>4
+  Error -24 (bad offset value)
+

+

+

+If any of the sequences \C, \G, or \L are present in a
+data line that is successfully matched, the substrings extracted by the
+convenience functions are output with C, G, or L after the string number
+instead of a colon. This is in addition to the normal full list. The string
+length (that is, the return from the extraction function) is given in
+parentheses after each string for \C and \G.
+

+

+Note that whereas patterns can be continued over several lines (a plain ">"
+prompt is used for continuations), data lines may not. However newlines can be
+included in data by means of the \n escape (or \r, \r\n, etc., depending on
+the newline sequence setting).
+

+
OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION

+

+When the alternative matching function, pcre[16|32]_dfa_exec(), is used (by
+means of the \D escape sequence or the -dfa command line option), the
+output consists of a list of all the matches that start at the first point in
+the subject where there is at least one match. For example:
+
+    re> /(tang|tangerine|tan)/
+  data> yellow tangerine\D
+   0: tangerine
+   1: tang
+   2: tan
+

+(Using the normal matching function on this data finds only "tang".) The
+longest matching string is always given first (and numbered zero). After a
+PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
+partially matching substring. (Note that this is the entire substring that was
+inspected during the partial match; it may include characters before the actual
+match start if a lookbehind assertion, \K, \b, or \B was involved.)
+

+

+If /g is present on the pattern, the search for further matches resumes
+at the end of the longest match. For example:
+
+    re> /(tang|tangerine|tan)/g
+  data> yellow tangerine and tangy sultana\D
+   0: tangerine
+   1: tang
+   2: tan
+   0: tang
+   1: tan
+   0: tan
+

+Since the matching function does not support substring capture, the escape
+sequences that are concerned with captured substrings are not relevant.
+

+
RESTARTING AFTER A PARTIAL MATCH

+

+When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
+indicating that the subject partially matched the pattern, you can restart the
+match with additional subject data by means of the \R escape sequence. For
+example:
+
+    re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
+  data> 23ja\P\D
+  Partial match: 23ja
+  data> n05\R\D
+   0: n05
+

+For further information about partial matching, see the
+pcrepartial
+documentation.
+

+
CALLOUTS

+

+If the pattern contains any callout requests, pcretest's callout function
+is called during matching. This works with both matching functions. By default,
+the called function displays the callout number, the start and current
+positions in the text at the callout time, and the next pattern item to be
+tested. For example:
+
+  --->pqrabcdef
+    0    ^  ^     \d
+

+This output indicates that callout number 0 occurred for a match attempt
+starting at the fourth character of the subject string, when the pointer was at
+the seventh character of the data, and when the next pattern item was \d. Just
+one circumflex is output if the start and current positions are the same.
+

+

+Callouts numbered 255 are assumed to be automatic callouts, inserted as a
+result of the /C pattern modifier. In this case, instead of showing the
+callout number, the offset in the pattern, preceded by a plus, is output. For
+example:
+
+    re> /\d?[A-E]\*/C
+  data> E*
+  --->E*
+   +0 ^      \d?
+   +3 ^      [A-E]
+   +8 ^^     \*
+  +10 ^ ^
+   0: E*
+

+If a pattern contains (*MARK) items, an additional line is output whenever
+a change of latest mark is passed to the callout function. For example:
+
+    re> /a(*MARK:X)bc/C
+  data> abc
+  --->abc
+   +0 ^       a
+   +1 ^^      (*MARK:X)
+  +10 ^^      b
+  Latest Mark: X
+  +11 ^ ^     c
+  +12 ^  ^
+   0: abc
+

+The mark changes between matching "a" and "b", but stays the same for the rest
+of the match, so nothing more is output. If, as a result of backtracking, the
+mark reverts to being unset, the text "<unset>" is output.
+

+

+The callout function in pcretest returns zero (carry on matching) by
+default, but you can use a \C item in a data line (as described above) to
+change this and other parameters of the callout.
+

+

+Inserting callouts can be helpful when using pcretest to check
+complicated regular expressions. For further information about callouts, see
+the
+pcrecallout
+documentation.
+

+
NON-PRINTING CHARACTERS

+

+When pcretest is outputting text in the compiled version of a pattern,
+bytes other than 32-126 are always treated as non-printing characters are are
+therefore shown as hex escapes.
+

+

+When pcretest is outputting text that is a matched part of a subject
+string, it behaves in the same way, unless a different locale has been set for
+the pattern (using the /L modifier). In this case, the isprint()
+function to distinguish printing and non-printing characters.
+

+
SAVING AND RELOADING COMPILED PATTERNS

+

+The facilities described in this section are not available when the POSIX
+interface to PCRE is being used, that is, when the /P pattern modifier is
+specified.
+

+

+When the POSIX interface is not in use, you can cause pcretest to write a
+compiled pattern to a file, by following the modifiers with > and a file name.
+For example:
+
+  /pattern/im >/some/file
+

+See the
+pcreprecompile
+documentation for a discussion about saving and re-using compiled patterns.
+Note that if the pattern was successfully studied with JIT optimization, the
+JIT data cannot be saved.
+

+

+The data that is written is binary. The first eight bytes are the length of the
+compiled pattern data followed by the length of the optional study data, each
+written as four bytes in big-endian order (most significant byte first). If
+there is no study data (either the pattern was not studied, or studying did not
+return any data), the second length is zero. The lengths are followed by an
+exact copy of the compiled pattern. If there is additional study data, this
+(excluding any JIT data) follows immediately after the compiled pattern. After
+writing the file, pcretest expects to read a new pattern.
+

+

+A saved pattern can be reloaded into pcretest by specifying < and a file
+name instead of a pattern. There must be no space between < and the file name,
+which must not contain a < character, as otherwise pcretest will
+interpret the line as a pattern delimited by < characters. For example:
+
+   re> </some/file
+  Compiled pattern loaded from /some/file
+  No study data
+

+If the pattern was previously studied with the JIT optimization, the JIT
+information cannot be saved and restored, and so is lost. When the pattern has
+been loaded, pcretest proceeds to read data lines in the usual way.
+

+

+You can copy a file written by pcretest to a different host and reload it
+there, even if the new host has opposite endianness to the one on which the
+pattern was compiled. For example, you can compile on an i86 machine and run on
+a SPARC machine. When a pattern is reloaded on a host with different
+endianness, the confirmation message is changed to:
+
+  Compiled pattern (byte-inverted) loaded from /some/file
+

+The test suite contains some saved pre-compiled patterns with different
+endianness. These are reloaded using "<!" instead of just "<". This suppresses
+the "(byte-inverted)" text so that the output is the same on all hosts. It also
+forces debugging output once the pattern has been reloaded.
+

+

+File names for saving and reloading can be absolute or relative, but note that
+the shell facility of expanding a file name that starts with a tilde (~) is not
+available.
+

+

+The ability to save and reload files in pcretest is intended for testing
+and experimentation. It is not intended for production use because only a
+single pattern can be written to a file. Furthermore, there is no facility for
+supplying custom character tables for use with a reloaded pattern. If the
+original pattern was compiled with custom tables, an attempt to match a subject
+string using a reloaded pattern is likely to cause pcretest to crash.
+Finally, if you attempt to load a file that is not in the correct format, the
+result is undefined.
+

+
SEE ALSO

+

+pcre(3), pcre16(3), pcre32(3), pcreapi(3),
+pcrecallout(3),
+pcrejit, pcrematching(3), pcrepartial(d),
+pcrepattern(3), pcreprecompile(3).
+

+
AUTHOR

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+
REVISION

+

+Last updated: 09 February 2014
+

+Copyright © 1997-2014 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/html/pcreunicode.html b/doc/html/pcreunicode.html
new file mode 100644
index 0000000..ab36bc6
--- /dev/null
+++ b/doc/html/pcreunicode.html
@@ -0,0 +1,262 @@
+
+
+pcreunicode specification
+
+
+
pcreunicode man page

+

+Return to the PCRE index page.
+

+

+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+

+

+UTF-8, UTF-16, UTF-32, AND UNICODE PROPERTY SUPPORT
+

+

+As well as UTF-8 support, PCRE also supports UTF-16 (from release 8.30) and
+UTF-32 (from release 8.32), by means of two additional libraries. They can be
+built as well as, or instead of, the 8-bit library.
+

+

+UTF-8 SUPPORT
+

+

+In order process UTF-8 strings, you must build PCRE's 8-bit library with UTF
+support, and, in addition, you must call
+pcre_compile()
+with the PCRE_UTF8 option flag, or the pattern must start with the sequence
+(*UTF8) or (*UTF). When either of these is the case, both the pattern and any
+subject strings that are matched against it are treated as UTF-8 strings
+instead of strings of individual 1-byte characters.
+

+

+UTF-16 AND UTF-32 SUPPORT
+

+

+In order process UTF-16 or UTF-32 strings, you must build PCRE's 16-bit or
+32-bit library with UTF support, and, in addition, you must call
+pcre16_compile()
+or
+pcre32_compile()
+with the PCRE_UTF16 or PCRE_UTF32 option flag, as appropriate. Alternatively,
+the pattern must start with the sequence (*UTF16), (*UTF32), as appropriate, or
+(*UTF), which can be used with either library. When UTF mode is set, both the
+pattern and any subject strings that are matched against it are treated as
+UTF-16 or UTF-32 strings instead of strings of individual 16-bit or 32-bit
+characters.
+

+

+UTF SUPPORT OVERHEAD
+

+

+If you compile PCRE with UTF support, but do not use it at run time, the
+library will be a bit bigger, but the additional run time overhead is limited
+to testing the PCRE_UTF[8|16|32] flag occasionally, so should not be very big.
+

+

+UNICODE PROPERTY SUPPORT
+

+

+If PCRE is built with Unicode character property support (which implies UTF
+support), the escape sequences \p{..}, \P{..}, and \X can be used.
+The available properties that can be tested are limited to the general
+category properties such as Lu for an upper case letter or Nd for a decimal
+number, the Unicode script names such as Arabic or Han, and the derived
+properties Any and L&. Full lists is given in the
+pcrepattern
+and
+pcresyntax
+documentation. Only the short names for properties are supported. For example,
+\p{L} matches a letter. Its Perl synonym, \p{Letter}, is not supported.
+Furthermore, in Perl, many properties may optionally be prefixed by "Is", for
+compatibility with Perl 5.6. PCRE does not support this.
+

+

+Validity of UTF-8 strings
+

+

+When you set the PCRE_UTF8 flag, the byte strings passed as patterns and
+subjects are (by default) checked for validity on entry to the relevant
+functions. The entire string is checked before any other processing takes
+place. From release 7.3 of PCRE, the check is according the rules of RFC 3629,
+which are themselves derived from the Unicode specification. Earlier releases
+of PCRE followed the rules of RFC 2279, which allows the full range of 31-bit
+values (0 to 0x7FFFFFFF). The current check allows only values in the range U+0
+to U+10FFFF, excluding the surrogate area. (From release 8.33 the so-called
+"non-character" code points are no longer excluded because Unicode corrigendum
+#9 makes it clear that they should not be.)
+

+

+Characters in the "Surrogate Area" of Unicode are reserved for use by UTF-16,
+where they are used in pairs to encode codepoints with values greater than
+0xFFFF. The code points that are encoded by UTF-16 pairs are available
+independently in the UTF-8 and UTF-32 encodings. (In other words, the whole
+surrogate thing is a fudge for UTF-16 which unfortunately messes up UTF-8 and
+UTF-32.)
+

+

+If an invalid UTF-8 string is passed to PCRE, an error return is given. At
+compile time, the only additional information is the offset to the first byte
+of the failing character. The run-time functions pcre_exec() and
+pcre_dfa_exec() also pass back this information, as well as a more
+detailed reason code if the caller has provided memory in which to do this.
+

+

+In some situations, you may already know that your strings are valid, and
+therefore want to skip these checks in order to improve performance, for
+example in the case of a long subject string that is being scanned repeatedly.
+If you set the PCRE_NO_UTF8_CHECK flag at compile time or at run time, PCRE
+assumes that the pattern or subject it is given (respectively) contains only
+valid UTF-8 codes. In this case, it does not diagnose an invalid UTF-8 string.
+

+

+Note that passing PCRE_NO_UTF8_CHECK to pcre_compile() just disables the
+check for the pattern; it does not also apply to subject strings. If you want
+to disable the check for a subject string you must pass this option to
+pcre_exec() or pcre_dfa_exec().
+

+

+If you pass an invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set, the result
+is undefined and your program may crash.
+

+

+Validity of UTF-16 strings
+

+

+When you set the PCRE_UTF16 flag, the strings of 16-bit data units that are
+passed as patterns and subjects are (by default) checked for validity on entry
+to the relevant functions. Values other than those in the surrogate range
+U+D800 to U+DFFF are independent code points. Values in the surrogate range
+must be used in pairs in the correct manner.
+

+

+If an invalid UTF-16 string is passed to PCRE, an error return is given. At
+compile time, the only additional information is the offset to the first data
+unit of the failing character. The run-time functions pcre16_exec() and
+pcre16_dfa_exec() also pass back this information, as well as a more
+detailed reason code if the caller has provided memory in which to do this.
+

+

+In some situations, you may already know that your strings are valid, and
+therefore want to skip these checks in order to improve performance. If you set
+the PCRE_NO_UTF16_CHECK flag at compile time or at run time, PCRE assumes that
+the pattern or subject it is given (respectively) contains only valid UTF-16
+sequences. In this case, it does not diagnose an invalid UTF-16 string.
+However, if an invalid string is passed, the result is undefined.
+

+

+Validity of UTF-32 strings
+

+

+When you set the PCRE_UTF32 flag, the strings of 32-bit data units that are
+passed as patterns and subjects are (by default) checked for validity on entry
+to the relevant functions.  This check allows only values in the range U+0
+to U+10FFFF, excluding the surrogate area U+D800 to U+DFFF.
+

+

+If an invalid UTF-32 string is passed to PCRE, an error return is given. At
+compile time, the only additional information is the offset to the first data
+unit of the failing character. The run-time functions pcre32_exec() and
+pcre32_dfa_exec() also pass back this information, as well as a more
+detailed reason code if the caller has provided memory in which to do this.
+

+

+In some situations, you may already know that your strings are valid, and
+therefore want to skip these checks in order to improve performance. If you set
+the PCRE_NO_UTF32_CHECK flag at compile time or at run time, PCRE assumes that
+the pattern or subject it is given (respectively) contains only valid UTF-32
+sequences. In this case, it does not diagnose an invalid UTF-32 string.
+However, if an invalid string is passed, the result is undefined.
+

+

+General comments about UTF modes
+

+

+1. Codepoints less than 256 can be specified in patterns by either braced or
+unbraced hexadecimal escape sequences (for example, \x{b3} or \xb3). Larger
+values have to use braced sequences.
+

+

+2. Octal numbers up to \777 are recognized, and in UTF-8 mode they match
+two-byte characters for values greater than \177.
+

+

+3. Repeat quantifiers apply to complete UTF characters, not to individual
+data units, for example: \x{100}{3}.
+

+

+4. The dot metacharacter matches one UTF character instead of a single data
+unit.
+

+

+5. The escape sequence \C can be used to match a single byte in UTF-8 mode, or
+a single 16-bit data unit in UTF-16 mode, or a single 32-bit data unit in
+UTF-32 mode, but its use can lead to some strange effects because it breaks up
+multi-unit characters (see the description of \C in the
+pcrepattern
+documentation). The use of \C is not supported in the alternative matching
+function pcre[16|32]_dfa_exec(), nor is it supported in UTF mode by the
+JIT optimization of pcre[16|32]_exec(). If JIT optimization is requested
+for a UTF pattern that contains \C, it will not succeed, and so the matching
+will be carried out by the normal interpretive function.
+

+

+6. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly
+test characters of any code value, but, by default, the characters that PCRE
+recognizes as digits, spaces, or word characters remain the same set as in
+non-UTF mode, all with values less than 256. This remains true even when PCRE
+is built to include Unicode property support, because to do otherwise would
+slow down PCRE in many common cases. Note in particular that this applies to
+\b and \B, because they are defined in terms of \w and \W. If you really
+want to test for a wider sense of, say, "digit", you can use explicit Unicode
+property tests such as \p{Nd}. Alternatively, if you set the PCRE_UCP option,
+the way that the character escapes work is changed so that Unicode properties
+are used to determine which characters match. There are more details in the
+section on
+generic character types
+in the
+pcrepattern
+documentation.
+

+

+7. Similarly, characters that match the POSIX named character classes are all
+low-valued characters, unless the PCRE_UCP option is set.
+

+

+8. However, the horizontal and vertical white space matching escapes (\h, \H,
+\v, and \V) do match all the appropriate Unicode characters, whether or not
+PCRE_UCP is set.
+

+

+9. Case-insensitive matching applies only to characters whose values are less
+than 128, unless PCRE is built with Unicode property support. A few Unicode
+characters such as Greek sigma have more than two codepoints that are
+case-equivalent. Up to and including PCRE release 8.31, only one-to-one case
+mappings were supported, but later releases (with Unicode property support) do
+treat as case-equivalent all versions of characters such as Greek sigma.
+

+

+AUTHOR
+

+

+Philip Hazel
+

+University Computing Service
+

+Cambridge CB2 3QH, England.
+

+

+

+REVISION
+

+

+Last updated: 27 February 2013
+

+Copyright © 1997-2013 University of Cambridge.
+

+

+Return to the PCRE index page.
+

diff --git a/doc/index.html.src b/doc/index.html.src
new file mode 100644
index 0000000..887f4d7
--- /dev/null
+++ b/doc/index.html.src
@@ -0,0 +1,185 @@
+
+      
+
+PCRE specification
+
+
+
Perl-compatible Regular Expressions (PCRE)

+

+The HTML documentation for PCRE consists of a number of pages that are listed
+below in alphabetical order. If you are new to PCRE, please read the first one
+first.
+

+
+
+
+    
+
+
+    
+
+
+    
+
+
+    
+
+
+    
+
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+    
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+    
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+    
+
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+    
+
+
+    
+
+
+    
+
pcre  Introductory page
pcre-config  Information about the installation configuration
pcre16  Discussion of the 16-bit PCRE library
pcre32  Discussion of the 32-bit PCRE library
pcreapi  PCRE's native API
pcrebuild  Building PCRE
pcrecallout  The callout facility
pcrecompat  Compability with Perl
pcrecpp  The C++ wrapper for the PCRE library
pcredemo  A demonstration C program that uses the PCRE library
pcregrep  The pcregrep command
pcrejit  Discussion of the just-in-time optimization support
pcrelimits  Details of size and other limits
pcrematching  Discussion of the two matching algorithms
pcrepartial  Using PCRE for partial matching
pcrepattern  Specification of the regular expressions supported by PCRE
pcreperform  Some comments on performance
pcreposix  The POSIX API to the PCRE 8-bit library
pcreprecompile  How to save and re-use compiled patterns
pcresample  Discussion of the pcredemo program
pcrestack  Discussion of PCRE's stack usage
pcresyntax  Syntax quick-reference summary
pcretest  The pcretest command for testing PCRE
pcreunicode  Discussion of Unicode and UTF-8/UTF-16/UTF-32 support

+
+

+There are also individual pages that summarize the interface for each function
+in the library. There is a single page for each triple of 8-bit/16-bit/32-bit
+functions.
+

+
+    
+
+
+    
+
+
+    
+
+
+    
+
+
+    
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+    
+
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+    
+
+
+    
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+
+    
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+
+    
+
+
+    
+
+
+    
+
+
+    
+
+
+    
+    
+
+    
+
+
+    
+
+
+    
+
+
+    
+
+
+    
+
+
+    
+
pcre_assign_jit_stack  Assign stack for JIT matching
pcre_compile  Compile a regular expression
pcre_compile2  Compile a regular expression (alternate interface)
pcre_config  Show build-time configuration options
pcre_copy_named_substring  Extract named substring into given buffer
pcre_copy_substring  Extract numbered substring into given buffer
pcre_dfa_exec  Match a compiled pattern to a subject string
+    (DFA algorithm; not Perl compatible)
pcre_exec  Match a compiled pattern to a subject string
+    (Perl compatible)
pcre_free_study  Free study data
pcre_free_substring  Free extracted substring
pcre_free_substring_list  Free list of extracted substrings
pcre_fullinfo  Extract information about a pattern
pcre_get_named_substring  Extract named substring into new memory
pcre_get_stringnumber  Convert captured string name to number
pcre_get_stringtable_entries  Find table entries for given string name
pcre_get_substring  Extract numbered substring into new memory
pcre_get_substring_list  Extract all substrings into new memory
pcre_jit_exec  Fast path interface to JIT matching
pcre_jit_stack_alloc  Create a stack for JIT matching
pcre_jit_stack_free  Free a JIT matching stack
pcre_maketables  Build character tables in current locale
pcre_pattern_to_host_byte_order  Convert compiled pattern to host byte order if necessary
pcre_refcount  Maintain reference count in compiled pattern
pcre_study  Study a compiled pattern
pcre_utf16_to_host_byte_order  Convert UTF-16 string to host byte order if necessary
pcre_utf32_to_host_byte_order  Convert UTF-32 string to host byte order if necessary
pcre_version  Return PCRE version and release date

+
+
diff --git a/doc/pcre-config.1 b/doc/pcre-config.1
new file mode 100644
index 0000000..52eb4fb
--- /dev/null
+++ b/doc/pcre-config.1
@@ -0,0 +1,92 @@
+.TH PCRE-CONFIG 1 "01 January 2012" "PCRE 8.30"
+.SH NAME
+pcre-config - program to return PCRE configuration
+.SH SYNOPSIS
+.rs
+.sp
+.nf
+.B pcre-config  [--prefix] [--exec-prefix] [--version] [--libs]
+.B "            [--libs16] [--libs32] [--libs-cpp] [--libs-posix]"
+.B "            [--cflags] [--cflags-posix]"
+.fi
+.
+.
+.SH DESCRIPTION
+.rs
+.sp
+\fBpcre-config\fP returns the configuration of the installed PCRE
+libraries and the options required to compile a program to use them. Some of
+the options apply only to the 8-bit, or 16-bit, or 32-bit libraries,
+respectively, and are
+not available if only one of those libraries has been built. If an unavailable
+option is encountered, the "usage" information is output.
+.
+.
+.SH OPTIONS
+.rs
+.TP 10
+\fB--prefix\fP
+Writes the directory prefix used in the PCRE installation for architecture
+independent files (\fI/usr\fP on many systems, \fI/usr/local\fP on some
+systems) to the standard output.
+.TP 10
+\fB--exec-prefix\fP
+Writes the directory prefix used in the PCRE installation for architecture
+dependent files (normally the same as \fB--prefix\fP) to the standard output.
+.TP 10
+\fB--version\fP
+Writes the version number of the installed PCRE libraries to the standard
+output.
+.TP 10
+\fB--libs\fP
+Writes to the standard output the command line options required to link
+with the 8-bit PCRE library (\fB-lpcre\fP on many systems).
+.TP 10
+\fB--libs16\fP
+Writes to the standard output the command line options required to link
+with the 16-bit PCRE library (\fB-lpcre16\fP on many systems).
+.TP 10
+\fB--libs32\fP
+Writes to the standard output the command line options required to link
+with the 32-bit PCRE library (\fB-lpcre32\fP on many systems).
+.TP 10
+\fB--libs-cpp\fP
+Writes to the standard output the command line options required to link with
+PCRE's C++ wrapper library (\fB-lpcrecpp\fP \fB-lpcre\fP on many
+systems).
+.TP 10
+\fB--libs-posix\fP
+Writes to the standard output the command line options required to link with
+PCRE's POSIX API wrapper library (\fB-lpcreposix\fP \fB-lpcre\fP on many
+systems).
+.TP 10
+\fB--cflags\fP
+Writes to the standard output the command line options required to compile
+files that use PCRE (this may include some \fB-I\fP options, but is blank on
+many systems).
+.TP 10
+\fB--cflags-posix\fP
+Writes to the standard output the command line options required to compile
+files that use PCRE's POSIX API wrapper library (this may include some \fB-I\fP
+options, but is blank on many systems).
+.
+.
+.SH "SEE ALSO"
+.rs
+.sp
+\fBpcre(3)\fP
+.
+.
+.SH AUTHOR
+.rs
+.sp
+This manual page was originally written by Mark Baker for the Debian GNU/Linux
+system. It has been subsequently revised as a generic PCRE man page.
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 24 June 2012
+.fi
diff --git a/doc/pcre-config.txt b/doc/pcre-config.txt
new file mode 100644
index 0000000..8503ab0
--- /dev/null
+++ b/doc/pcre-config.txt
@@ -0,0 +1,86 @@
+PCRE-CONFIG(1)              General Commands Manual             PCRE-CONFIG(1)
+
+
+
+NAME
+       pcre-config - program to return PCRE configuration
+
+SYNOPSIS
+
+       pcre-config [--prefix] [--exec-prefix] [--version] [--libs]
+                   [--libs16] [--libs32] [--libs-cpp] [--libs-posix]
+                   [--cflags] [--cflags-posix]
+
+
+DESCRIPTION
+
+       pcre-config  returns  the configuration of the installed PCRE libraries
+       and the options required to compile a program to use them. Some of  the
+       options  apply  only  to  the  8-bit,  or  16-bit, or 32-bit libraries,
+       respectively, and are not available if only one of those libraries  has
+       been built. If an unavailable option is encountered, the "usage" infor-
+       mation is output.
+
+
+OPTIONS
+
+       --prefix  Writes the directory prefix used in the PCRE installation for
+                 architecture   independent   files  (/usr  on  many  systems,
+                 /usr/local on some systems) to the standard output.
+
+       --exec-prefix
+                 Writes the directory prefix used in the PCRE installation for
+                 architecture  dependent files (normally the same as --prefix)
+                 to the standard output.
+
+       --version Writes the version number of the installed PCRE libraries  to
+                 the standard output.
+
+       --libs    Writes  to  the  standard  output  the  command  line options
+                 required to link with the 8-bit PCRE library (-lpcre on  many
+                 systems).
+
+       --libs16  Writes  to  the  standard  output  the  command  line options
+                 required to link with the 16-bit PCRE  library  (-lpcre16  on
+                 many systems).
+
+       --libs32  Writes  to  the  standard  output  the  command  line options
+                 required to link with the 32-bit PCRE  library  (-lpcre32  on
+                 many systems).
+
+       --libs-cpp
+                 Writes  to  the  standard  output  the  command  line options
+                 required to link with PCRE's C++ wrapper  library  (-lpcrecpp
+                 -lpcre on many systems).
+
+       --libs-posix
+                 Writes  to  the  standard  output  the  command  line options
+                 required to  link  with  PCRE's  POSIX  API  wrapper  library
+                 (-lpcreposix -lpcre on many systems).
+
+       --cflags  Writes  to  the  standard  output  the  command  line options
+                 required to compile files that use  PCRE  (this  may  include
+                 some -I options, but is blank on many systems).
+
+       --cflags-posix
+                 Writes  to  the  standard  output  the  command  line options
+                 required to compile files that use PCRE's POSIX  API  wrapper
+                 library  (this  may  include some -I options, but is blank on
+                 many systems).
+
+
+SEE ALSO
+
+       pcre(3)
+
+
+AUTHOR
+
+       This manual page was originally written by Mark Baker  for  the  Debian
+       GNU/Linux  system.  It  has been subsequently revised as a generic PCRE
+       man page.
+
+
+REVISION
+
+       Last updated: 24 June 2012
diff --git a/doc/pcre.3 b/doc/pcre.3
new file mode 100644
index 0000000..4eda404
--- /dev/null
+++ b/doc/pcre.3
@@ -0,0 +1,218 @@
+.TH PCRE 3 "08 January 2014" "PCRE 8.35"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH INTRODUCTION
+.rs
+.sp
+The PCRE library is a set of functions that implement regular expression
+pattern matching using the same syntax and semantics as Perl, with just a few
+differences. Some features that appeared in Python and PCRE before they
+appeared in Perl are also available using the Python syntax, there is some
+support for one or two .NET and Oniguruma syntax items, and there is an option
+for requesting some minor changes that give better JavaScript compatibility.
+.P
+Starting with release 8.30, it is possible to compile two separate PCRE
+libraries: the original, which supports 8-bit character strings (including
+UTF-8 strings), and a second library that supports 16-bit character strings
+(including UTF-16 strings). The build process allows either one or both to be
+built. The majority of the work to make this possible was done by Zoltan
+Herczeg.
+.P
+Starting with release 8.32 it is possible to compile a third separate PCRE
+library that supports 32-bit character strings (including UTF-32 strings). The
+build process allows any combination of the 8-, 16- and 32-bit libraries. The
+work to make this possible was done by Christian Persch.
+.P
+The three libraries contain identical sets of functions, except that the names
+in the 16-bit library start with \fBpcre16_\fP instead of \fBpcre_\fP, and the
+names in the 32-bit library start with \fBpcre32_\fP instead of \fBpcre_\fP. To
+avoid over-complication and reduce the documentation maintenance load, most of
+the documentation describes the 8-bit library, with the differences for the
+16-bit and 32-bit libraries described separately in the
+.\" HREF
+\fBpcre16\fP
+and
+.\" HREF
+\fBpcre32\fP
+.\"
+pages. References to functions or structures of the form \fIpcre[16|32]_xxx\fP
+should be read as meaning "\fIpcre_xxx\fP when using the 8-bit library,
+\fIpcre16_xxx\fP when using the 16-bit library, or \fIpcre32_xxx\fP when using
+the 32-bit library".
+.P
+The current implementation of PCRE corresponds approximately with Perl 5.12,
+including support for UTF-8/16/32 encoded strings and Unicode general category
+properties. However, UTF-8/16/32 and Unicode support has to be explicitly
+enabled; it is not the default. The Unicode tables correspond to Unicode
+release 6.3.0.
+.P
+In addition to the Perl-compatible matching function, PCRE contains an
+alternative function that matches the same compiled patterns in a different
+way. In certain circumstances, the alternative function has some advantages.
+For a discussion of the two matching algorithms, see the
+.\" HREF
+\fBpcrematching\fP
+.\"
+page.
+.P
+PCRE is written in C and released as a C library. A number of people have
+written wrappers and interfaces of various kinds. In particular, Google Inc.
+have provided a comprehensive C++ wrapper for the 8-bit library. This is now
+included as part of the PCRE distribution. The
+.\" HREF
+\fBpcrecpp\fP
+.\"
+page has details of this interface. Other people's contributions can be found
+in the \fIContrib\fP directory at the primary FTP site, which is:
+.sp
+.\" HTML 
+.\" 
+ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
+.\"
+.P
+Details of exactly which Perl regular expression features are and are not
+supported by PCRE are given in separate documents. See the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+and
+.\" HREF
+\fBpcrecompat\fP
+.\"
+pages. There is a syntax summary in the
+.\" HREF
+\fBpcresyntax\fP
+.\"
+page.
+.P
+Some features of PCRE can be included, excluded, or changed when the library is
+built. The
+.\" HREF
+\fBpcre_config()\fP
+.\"
+function makes it possible for a client to discover which features are
+available. The features themselves are described in the
+.\" HREF
+\fBpcrebuild\fP
+.\"
+page. Documentation about building PCRE for various operating systems can be
+found in the
+.\" HTML 
+.\" 
+\fBREADME\fP
+.\"
+and
+.\" HTML 
+.\" 
+\fBNON-AUTOTOOLS_BUILD\fP
+.\"
+files in the source distribution.
+.P
+The libraries contains a number of undocumented internal functions and data
+tables that are used by more than one of the exported external functions, but
+which are not intended for use by external callers. Their names all begin with
+"_pcre_" or "_pcre16_" or "_pcre32_", which hopefully will not provoke any name
+clashes. In some environments, it is possible to control which external symbols
+are exported when a shared library is built, and in these cases the
+undocumented symbols are not exported.
+.
+.
+.SH "SECURITY CONSIDERATIONS"
+.rs
+.sp
+If you are using PCRE in a non-UTF application that permits users to supply
+arbitrary patterns for compilation, you should be aware of a feature that
+allows users to turn on UTF support from within a pattern, provided that PCRE
+was built with UTF support. For example, an 8-bit pattern that begins with
+"(*UTF8)" or "(*UTF)" turns on UTF-8 mode, which interprets patterns and
+subjects as strings of UTF-8 characters instead of individual 8-bit characters.
+This causes both the pattern and any data against which it is matched to be
+checked for UTF-8 validity. If the data string is very long, such a check might
+use sufficiently many resources as to cause your application to lose
+performance.
+.P
+One way of guarding against this possibility is to use the
+\fBpcre_fullinfo()\fP function to check the compiled pattern's options for UTF.
+Alternatively, from release 8.33, you can set the PCRE_NEVER_UTF option at
+compile time. This causes an compile time error if a pattern contains a
+UTF-setting sequence.
+.P
+If your application is one that supports UTF, be aware that validity checking
+can take time. If the same data string is to be matched many times, you can use
+the PCRE_NO_UTF[8|16|32]_CHECK option for the second and subsequent matches to
+save redundant checks.
+.P
+Another way that performance can be hit is by running a pattern that has a very
+large search tree against a string that will never match. Nested unlimited
+repeats in a pattern are a common example. PCRE provides some protection
+against this: see the PCRE_EXTRA_MATCH_LIMIT feature in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page.
+.
+.
+.SH "USER DOCUMENTATION"
+.rs
+.sp
+The user documentation for PCRE comprises a number of different sections. In
+the "man" format, each of these is a separate "man page". In the HTML format,
+each is a separate page, linked from the index page. In the plain text format,
+the descriptions of the \fBpcregrep\fP and \fBpcretest\fP programs are in files
+called \fBpcregrep.txt\fP and \fBpcretest.txt\fP, respectively. The remaining
+sections, except for the \fBpcredemo\fP section (which is a program listing),
+are concatenated in \fBpcre.txt\fP, for ease of searching. The sections are as
+follows:
+.sp
+  pcre              this document
+  pcre-config       show PCRE installation configuration information
+  pcre16            details of the 16-bit library
+  pcre32            details of the 32-bit library
+  pcreapi           details of PCRE's native C API
+  pcrebuild         building PCRE
+  pcrecallout       details of the callout feature
+  pcrecompat        discussion of Perl compatibility
+  pcrecpp           details of the C++ wrapper for the 8-bit library
+  pcredemo          a demonstration C program that uses PCRE
+  pcregrep          description of the \fBpcregrep\fP command (8-bit only)
+  pcrejit           discussion of the just-in-time optimization support
+  pcrelimits        details of size and other limits
+  pcrematching      discussion of the two matching algorithms
+  pcrepartial       details of the partial matching facility
+.\" JOIN
+  pcrepattern       syntax and semantics of supported
+                      regular expressions
+  pcreperform       discussion of performance issues
+  pcreposix         the POSIX-compatible C API for the 8-bit library
+  pcreprecompile    details of saving and re-using precompiled patterns
+  pcresample        discussion of the pcredemo program
+  pcrestack         discussion of stack usage
+  pcresyntax        quick syntax reference
+  pcretest          description of the \fBpcretest\fP testing command
+  pcreunicode       discussion of Unicode and UTF-8/16/32 support
+.sp
+In the "man" and HTML formats, there is also a short page for each C library
+function, listing its arguments and results.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.P
+Putting an actual email address here seems to have been a spam magnet, so I've
+taken it away. If you want to email me, use my two initials, followed by the
+two digits 10, at the domain cam.ac.uk.
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 08 January 2014
+Copyright (c) 1997-2014 University of Cambridge.
+.fi
diff --git a/doc/pcre.txt b/doc/pcre.txt
new file mode 100644
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+-----------------------------------------------------------------------------
+This file contains a concatenation of the PCRE man pages, converted to plain
+text format for ease of searching with a text editor, or for use on systems
+that do not have a man page processor. The small individual files that give
+synopses of each function in the library have not been included. Neither has
+the pcredemo program. There are separate text files for the pcregrep and
+pcretest commands.
+-----------------------------------------------------------------------------
+
+
+PCRE(3)                    Library Functions Manual                    PCRE(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+INTRODUCTION
+
+       The  PCRE  library is a set of functions that implement regular expres-
+       sion pattern matching using the same syntax and semantics as Perl, with
+       just  a few differences. Some features that appeared in Python and PCRE
+       before they appeared in Perl are also available using the  Python  syn-
+       tax,  there  is  some  support for one or two .NET and Oniguruma syntax
+       items, and there is an option for requesting some  minor  changes  that
+       give better JavaScript compatibility.
+
+       Starting with release 8.30, it is possible to compile two separate PCRE
+       libraries:  the  original,  which  supports  8-bit  character   strings
+       (including  UTF-8  strings),  and a second library that supports 16-bit
+       character strings (including UTF-16 strings). The build process  allows
+       either  one  or both to be built. The majority of the work to make this
+       possible was done by Zoltan Herczeg.
+
+       Starting with release 8.32 it is possible to compile a  third  separate
+       PCRE  library  that supports 32-bit character strings (including UTF-32
+       strings). The build process allows any combination of the 8-,  16-  and
+       32-bit  libraries. The work to make this possible was done by Christian
+       Persch.
+
+       The three libraries contain identical sets of  functions,  except  that
+       the  names  in  the 16-bit library start with pcre16_ instead of pcre_,
+       and the names in the 32-bit  library  start  with  pcre32_  instead  of
+       pcre_.  To avoid over-complication and reduce the documentation mainte-
+       nance load, most of the documentation describes the 8-bit library, with
+       the  differences  for  the  16-bit and 32-bit libraries described sepa-
+       rately in the pcre16 and  pcre32  pages.  References  to  functions  or
+       structures  of  the  form  pcre[16|32]_xxx  should  be  read as meaning
+       "pcre_xxx when using the  8-bit  library,  pcre16_xxx  when  using  the
+       16-bit library, or pcre32_xxx when using the 32-bit library".
+
+       The  current implementation of PCRE corresponds approximately with Perl
+       5.12, including support for UTF-8/16/32  encoded  strings  and  Unicode
+       general  category  properties. However, UTF-8/16/32 and Unicode support
+       has to be explicitly enabled; it is not the default. The Unicode tables
+       correspond to Unicode release 6.3.0.
+
+       In  addition to the Perl-compatible matching function, PCRE contains an
+       alternative function that matches the same compiled patterns in a  dif-
+       ferent way. In certain circumstances, the alternative function has some
+       advantages.  For a discussion of the two matching algorithms,  see  the
+       pcrematching page.
+
+       PCRE  is  written  in C and released as a C library. A number of people
+       have written wrappers and interfaces of various kinds.  In  particular,
+       Google  Inc.   have  provided a comprehensive C++ wrapper for the 8-bit
+       library. This is now included as part of  the  PCRE  distribution.  The
+       pcrecpp  page  has  details of this interface. Other people's contribu-
+       tions can be found in the Contrib directory at the  primary  FTP  site,
+       which is:
+
+       ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
+
+       Details  of  exactly which Perl regular expression features are and are
+       not supported by PCRE are given in separate documents. See the pcrepat-
+       tern  and pcrecompat pages. There is a syntax summary in the pcresyntax
+       page.
+
+       Some features of PCRE can be included, excluded, or  changed  when  the
+       library  is  built.  The pcre_config() function makes it possible for a
+       client to discover which features are  available.  The  features  them-
+       selves  are described in the pcrebuild page. Documentation about build-
+       ing PCRE for various operating systems can be found in the  README  and
+       NON-AUTOTOOLS_BUILD files in the source distribution.
+
+       The  libraries contains a number of undocumented internal functions and
+       data tables that are used by more than one  of  the  exported  external
+       functions,  but  which  are  not  intended for use by external callers.
+       Their names all begin with "_pcre_" or "_pcre16_" or "_pcre32_",  which
+       hopefully  will  not provoke any name clashes. In some environments, it
+       is possible to control which  external  symbols  are  exported  when  a
+       shared  library  is  built, and in these cases the undocumented symbols
+       are not exported.
+
+
+SECURITY CONSIDERATIONS
+
+       If you are using PCRE in a non-UTF application that  permits  users  to
+       supply  arbitrary  patterns  for  compilation, you should be aware of a
+       feature that allows users to turn on UTF support from within a pattern,
+       provided  that  PCRE  was built with UTF support. For example, an 8-bit
+       pattern that begins with "(*UTF8)" or "(*UTF)"  turns  on  UTF-8  mode,
+       which  interprets  patterns and subjects as strings of UTF-8 characters
+       instead of individual 8-bit characters.  This causes both  the  pattern
+       and any data against which it is matched to be checked for UTF-8 valid-
+       ity. If the data string is very long, such a  check  might  use  suffi-
+       ciently  many  resources  as  to cause your application to lose perfor-
+       mance.
+
+       One  way  of  guarding  against  this  possibility  is   to   use   the
+       pcre_fullinfo()  function  to  check the compiled pattern's options for
+       UTF.  Alternatively, from release 8.33, you can set the  PCRE_NEVER_UTF
+       option  at compile time. This causes an compile time error if a pattern
+       contains a UTF-setting sequence.
+
+       If your application is one that supports UTF, be  aware  that  validity
+       checking  can  take time. If the same data string is to be matched many
+       times, you can use the PCRE_NO_UTF[8|16|32]_CHECK option for the second
+       and subsequent matches to save redundant checks.
+
+       Another  way  that  performance can be hit is by running a pattern that
+       has a very large search tree against a string that  will  never  match.
+       Nested  unlimited  repeats in a pattern are a common example. PCRE pro-
+       vides some protection against this: see the PCRE_EXTRA_MATCH_LIMIT fea-
+       ture in the pcreapi page.
+
+
+USER DOCUMENTATION
+
+       The  user  documentation  for PCRE comprises a number of different sec-
+       tions. In the "man" format, each of these is a separate "man page".  In
+       the  HTML  format, each is a separate page, linked from the index page.
+       In the plain text format, the descriptions of the pcregrep and pcretest
+       programs  are  in  files  called pcregrep.txt and pcretest.txt, respec-
+       tively. The remaining sections, except for the pcredemo section  (which
+       is  a  program  listing),  are  concatenated  in  pcre.txt, for ease of
+       searching. The sections are as follows:
+
+         pcre              this document
+         pcre-config       show PCRE installation configuration information
+         pcre16            details of the 16-bit library
+         pcre32            details of the 32-bit library
+         pcreapi           details of PCRE's native C API
+         pcrebuild         building PCRE
+         pcrecallout       details of the callout feature
+         pcrecompat        discussion of Perl compatibility
+         pcrecpp           details of the C++ wrapper for the 8-bit library
+         pcredemo          a demonstration C program that uses PCRE
+         pcregrep          description of the pcregrep command (8-bit only)
+         pcrejit           discussion of the just-in-time optimization support
+         pcrelimits        details of size and other limits
+         pcrematching      discussion of the two matching algorithms
+         pcrepartial       details of the partial matching facility
+         pcrepattern       syntax and semantics of supported
+                             regular expressions
+         pcreperform       discussion of performance issues
+         pcreposix         the POSIX-compatible C API for the 8-bit library
+         pcreprecompile    details of saving and re-using precompiled patterns
+         pcresample        discussion of the pcredemo program
+         pcrestack         discussion of stack usage
+         pcresyntax        quick syntax reference
+         pcretest          description of the pcretest testing command
+         pcreunicode       discussion of Unicode and UTF-8/16/32 support
+
+       In the "man" and HTML formats, there is also a short page  for  each  C
+       library function, listing its arguments and results.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+       Putting  an actual email address here seems to have been a spam magnet,
+       so I've taken it away. If you want to email me, use  my  two  initials,
+       followed by the two digits 10, at the domain cam.ac.uk.
+
+
+REVISION
+
+       Last updated: 08 January 2014
+       Copyright (c) 1997-2014 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCRE(3)                    Library Functions Manual                    PCRE(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+       #include 
+
+
+PCRE 16-BIT API BASIC FUNCTIONS
+
+       pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options,
+            const char **errptr, int *erroffset,
+            const unsigned char *tableptr);
+
+       pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options,
+            int *errorcodeptr,
+            const char **errptr, int *erroffset,
+            const unsigned char *tableptr);
+
+       pcre16_extra *pcre16_study(const pcre16 *code, int options,
+            const char **errptr);
+
+       void pcre16_free_study(pcre16_extra *extra);
+
+       int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
+            PCRE_SPTR16 subject, int length, int startoffset,
+            int options, int *ovector, int ovecsize);
+
+       int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
+            PCRE_SPTR16 subject, int length, int startoffset,
+            int options, int *ovector, int ovecsize,
+            int *workspace, int wscount);
+
+
+PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
+
+       int pcre16_copy_named_substring(const pcre16 *code,
+            PCRE_SPTR16 subject, int *ovector,
+            int stringcount, PCRE_SPTR16 stringname,
+            PCRE_UCHAR16 *buffer, int buffersize);
+
+       int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
+            int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
+            int buffersize);
+
+       int pcre16_get_named_substring(const pcre16 *code,
+            PCRE_SPTR16 subject, int *ovector,
+            int stringcount, PCRE_SPTR16 stringname,
+            PCRE_SPTR16 *stringptr);
+
+       int pcre16_get_stringnumber(const pcre16 *code,
+            PCRE_SPTR16 name);
+
+       int pcre16_get_stringtable_entries(const pcre16 *code,
+            PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
+
+       int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
+            int stringcount, int stringnumber,
+            PCRE_SPTR16 *stringptr);
+
+       int pcre16_get_substring_list(PCRE_SPTR16 subject,
+            int *ovector, int stringcount, PCRE_SPTR16 **listptr);
+
+       void pcre16_free_substring(PCRE_SPTR16 stringptr);
+
+       void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
+
+
+PCRE 16-BIT API AUXILIARY FUNCTIONS
+
+       pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
+
+       void pcre16_jit_stack_free(pcre16_jit_stack *stack);
+
+       void pcre16_assign_jit_stack(pcre16_extra *extra,
+            pcre16_jit_callback callback, void *data);
+
+       const unsigned char *pcre16_maketables(void);
+
+       int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
+            int what, void *where);
+
+       int pcre16_refcount(pcre16 *code, int adjust);
+
+       int pcre16_config(int what, void *where);
+
+       const char *pcre16_version(void);
+
+       int pcre16_pattern_to_host_byte_order(pcre16 *code,
+            pcre16_extra *extra, const unsigned char *tables);
+
+
+PCRE 16-BIT API INDIRECTED FUNCTIONS
+
+       void *(*pcre16_malloc)(size_t);
+
+       void (*pcre16_free)(void *);
+
+       void *(*pcre16_stack_malloc)(size_t);
+
+       void (*pcre16_stack_free)(void *);
+
+       int (*pcre16_callout)(pcre16_callout_block *);
+
+
+PCRE 16-BIT API 16-BIT-ONLY FUNCTION
+
+       int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
+            PCRE_SPTR16 input, int length, int *byte_order,
+            int keep_boms);
+
+
+THE PCRE 16-BIT LIBRARY
+
+       Starting  with  release  8.30, it is possible to compile a PCRE library
+       that supports 16-bit character strings, including  UTF-16  strings,  as
+       well  as  or instead of the original 8-bit library. The majority of the
+       work to make  this  possible  was  done  by  Zoltan  Herczeg.  The  two
+       libraries contain identical sets of functions, used in exactly the same
+       way. Only the names of the functions and the data types of their  argu-
+       ments  and results are different. To avoid over-complication and reduce
+       the documentation maintenance load,  most  of  the  PCRE  documentation
+       describes  the  8-bit  library,  with only occasional references to the
+       16-bit library. This page describes what is different when you use  the
+       16-bit library.
+
+       WARNING:  A  single  application can be linked with both libraries, but
+       you must take care when processing any particular pattern to use  func-
+       tions  from  just one library. For example, if you want to study a pat-
+       tern that was compiled with  pcre16_compile(),  you  must  do  so  with
+       pcre16_study(), not pcre_study(), and you must free the study data with
+       pcre16_free_study().
+
+
+THE HEADER FILE
+
+       There is only one header file, pcre.h. It contains prototypes  for  all
+       the functions in all libraries, as well as definitions of flags, struc-
+       tures, error codes, etc.
+
+
+THE LIBRARY NAME
+
+       In Unix-like systems, the 16-bit library is called libpcre16,  and  can
+       normally  be  accesss  by adding -lpcre16 to the command for linking an
+       application that uses PCRE.
+
+
+STRING TYPES
+
+       In the 8-bit library, strings are passed to PCRE library  functions  as
+       vectors  of  bytes  with  the  C  type "char *". In the 16-bit library,
+       strings are passed as vectors of unsigned 16-bit quantities. The  macro
+       PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
+       defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
+       int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
+       as "unsigned short int", but checks that it really  is  a  16-bit  data
+       type.  If  it is not, the build fails with an error message telling the
+       maintainer to modify the definition appropriately.
+
+
+STRUCTURE TYPES
+
+       The types of the opaque structures that are used  for  compiled  16-bit
+       patterns  and  JIT stacks are pcre16 and pcre16_jit_stack respectively.
+       The  type  of  the  user-accessible  structure  that  is  returned   by
+       pcre16_study()  is  pcre16_extra, and the type of the structure that is
+       used for passing data to a callout  function  is  pcre16_callout_block.
+       These structures contain the same fields, with the same names, as their
+       8-bit counterparts. The only difference is that pointers  to  character
+       strings are 16-bit instead of 8-bit types.
+
+
+16-BIT FUNCTIONS
+
+       For  every function in the 8-bit library there is a corresponding func-
+       tion in the 16-bit library with a name that starts with pcre16_ instead
+       of  pcre_.  The  prototypes are listed above. In addition, there is one
+       extra function, pcre16_utf16_to_host_byte_order(). This  is  a  utility
+       function  that converts a UTF-16 character string to host byte order if
+       necessary. The other 16-bit  functions  expect  the  strings  they  are
+       passed to be in host byte order.
+
+       The input and output arguments of pcre16_utf16_to_host_byte_order() may
+       point to the same address, that is, conversion in place  is  supported.
+       The output buffer must be at least as long as the input.
+
+       The  length  argument  specifies the number of 16-bit data units in the
+       input string; a negative value specifies a zero-terminated string.
+
+       If byte_order is NULL, it is assumed that the string starts off in host
+       byte  order. This may be changed by byte-order marks (BOMs) anywhere in
+       the string (commonly as the first character).
+
+       If byte_order is not NULL, a non-zero value of the integer to which  it
+       points  means  that  the input starts off in host byte order, otherwise
+       the opposite order is assumed. Again, BOMs in  the  string  can  change
+       this. The final byte order is passed back at the end of processing.
+
+       If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
+       copied into the output string. Otherwise they are discarded.
+
+       The result of the function is the number of 16-bit  units  placed  into
+       the  output  buffer,  including  the  zero terminator if the string was
+       zero-terminated.
+
+
+SUBJECT STRING OFFSETS
+
+       The lengths and starting offsets of subject strings must  be  specified
+       in  16-bit  data units, and the offsets within subject strings that are
+       returned by the matching functions are in also 16-bit units rather than
+       bytes.
+
+
+NAMED SUBPATTERNS
+
+       The  name-to-number translation table that is maintained for named sub-
+       patterns uses 16-bit characters.  The  pcre16_get_stringtable_entries()
+       function returns the length of each entry in the table as the number of
+       16-bit data units.
+
+
+OPTION NAMES
+
+       There   are   two   new   general   option   names,   PCRE_UTF16    and
+       PCRE_NO_UTF16_CHECK,     which     correspond    to    PCRE_UTF8    and
+       PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
+       define  the  same bits in the options word. There is a discussion about
+       the validity of UTF-16 strings in the pcreunicode page.
+
+       For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16
+       that  returns  1  if UTF-16 support is configured, otherwise 0. If this
+       option  is  given  to  pcre_config()  or  pcre32_config(),  or  if  the
+       PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF32  option is given to pcre16_con-
+       fig(), the result is the PCRE_ERROR_BADOPTION error.
+
+
+CHARACTER CODES
+
+       In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
+       treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
+       that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
+       types  for characters less than 0xff can therefore be influenced by the
+       locale in the same way as before.  Characters greater  than  0xff  have
+       only one case, and no "type" (such as letter or digit).
+
+       In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
+       0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
+       because  those  are "surrogate" values that are used in pairs to encode
+       values greater than 0xffff.
+
+       A UTF-16 string can indicate its endianness by special code knows as  a
+       byte-order mark (BOM). The PCRE functions do not handle this, expecting
+       strings  to  be  in  host  byte  order.  A  utility   function   called
+       pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
+       above).
+
+
+ERROR NAMES
+
+       The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
+       spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
+       given when a compiled pattern is passed to a  function  that  processes
+       patterns  in  the  other  mode, for example, if a pattern compiled with
+       pcre_compile() is passed to pcre16_exec().
+
+       There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
+       invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
+       UTF-8 strings that are described in the section entitled "Reason  codes
+       for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
+       are:
+
+         PCRE_UTF16_ERR1  Missing low surrogate at end of string
+         PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
+         PCRE_UTF16_ERR3  Isolated low surrogate
+         PCRE_UTF16_ERR4  Non-character
+
+
+ERROR TEXTS
+
+       If there is an error while compiling a pattern, the error text that  is
+       passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
+       character string, zero-terminated.
+
+
+CALLOUTS
+
+       The subject and mark fields in the callout block that is  passed  to  a
+       callout function point to 16-bit vectors.
+
+
+TESTING
+
+       The  pcretest  program continues to operate with 8-bit input and output
+       files, but it can be used for testing the 16-bit library. If it is  run
+       with the command line option -16, patterns and subject strings are con-
+       verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
+       library  functions  are used instead of the 8-bit ones. Returned 16-bit
+       strings are converted to 8-bit for output. If both the  8-bit  and  the
+       32-bit libraries were not compiled, pcretest defaults to 16-bit and the
+       -16 option is ignored.
+
+       When PCRE is being built, the RunTest script that is  called  by  "make
+       check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
+       16-bit and 32-bit libraries has been built, and runs the  tests  appro-
+       priately.
+
+
+NOT SUPPORTED IN 16-BIT MODE
+
+       Not all the features of the 8-bit library are available with the 16-bit
+       library. The C++ and POSIX wrapper functions  support  only  the  8-bit
+       library, and the pcregrep program is at present 8-bit only.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 12 May 2013
+       Copyright (c) 1997-2013 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCRE(3)                    Library Functions Manual                    PCRE(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+       #include 
+
+
+PCRE 32-BIT API BASIC FUNCTIONS
+
+       pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
+            const char **errptr, int *erroffset,
+            const unsigned char *tableptr);
+
+       pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
+            int *errorcodeptr,
+            const unsigned char *tableptr);
+
+       pcre32_extra *pcre32_study(const pcre32 *code, int options,
+            const char **errptr);
+
+       void pcre32_free_study(pcre32_extra *extra);
+
+       int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
+            PCRE_SPTR32 subject, int length, int startoffset,
+            int options, int *ovector, int ovecsize);
+
+       int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
+            PCRE_SPTR32 subject, int length, int startoffset,
+            int options, int *ovector, int ovecsize,
+            int *workspace, int wscount);
+
+
+PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
+
+       int pcre32_copy_named_substring(const pcre32 *code,
+            PCRE_SPTR32 subject, int *ovector,
+            int stringcount, PCRE_SPTR32 stringname,
+            PCRE_UCHAR32 *buffer, int buffersize);
+
+       int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
+            int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
+            int buffersize);
+
+       int pcre32_get_named_substring(const pcre32 *code,
+            PCRE_SPTR32 subject, int *ovector,
+            int stringcount, PCRE_SPTR32 stringname,
+            PCRE_SPTR32 *stringptr);
+
+       int pcre32_get_stringnumber(const pcre32 *code,
+            PCRE_SPTR32 name);
+
+       int pcre32_get_stringtable_entries(const pcre32 *code,
+            PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);
+
+       int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
+            int stringcount, int stringnumber,
+            PCRE_SPTR32 *stringptr);
+
+       int pcre32_get_substring_list(PCRE_SPTR32 subject,
+            int *ovector, int stringcount, PCRE_SPTR32 **listptr);
+
+       void pcre32_free_substring(PCRE_SPTR32 stringptr);
+
+       void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);
+
+
+PCRE 32-BIT API AUXILIARY FUNCTIONS
+
+       pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);
+
+       void pcre32_jit_stack_free(pcre32_jit_stack *stack);
+
+       void pcre32_assign_jit_stack(pcre32_extra *extra,
+            pcre32_jit_callback callback, void *data);
+
+       const unsigned char *pcre32_maketables(void);
+
+       int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
+            int what, void *where);
+
+       int pcre32_refcount(pcre32 *code, int adjust);
+
+       int pcre32_config(int what, void *where);
+
+       const char *pcre32_version(void);
+
+       int pcre32_pattern_to_host_byte_order(pcre32 *code,
+            pcre32_extra *extra, const unsigned char *tables);
+
+
+PCRE 32-BIT API INDIRECTED FUNCTIONS
+
+       void *(*pcre32_malloc)(size_t);
+
+       void (*pcre32_free)(void *);
+
+       void *(*pcre32_stack_malloc)(size_t);
+
+       void (*pcre32_stack_free)(void *);
+
+       int (*pcre32_callout)(pcre32_callout_block *);
+
+
+PCRE 32-BIT API 32-BIT-ONLY FUNCTION
+
+       int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
+            PCRE_SPTR32 input, int length, int *byte_order,
+            int keep_boms);
+
+
+THE PCRE 32-BIT LIBRARY
+
+       Starting  with  release  8.32, it is possible to compile a PCRE library
+       that supports 32-bit character strings, including  UTF-32  strings,  as
+       well as or instead of the original 8-bit library. This work was done by
+       Christian Persch, based on the work done  by  Zoltan  Herczeg  for  the
+       16-bit  library.  All  three  libraries contain identical sets of func-
+       tions, used in exactly the same way.  Only the names of  the  functions
+       and  the  data  types  of their arguments and results are different. To
+       avoid over-complication and reduce the documentation maintenance  load,
+       most  of  the PCRE documentation describes the 8-bit library, with only
+       occasional references to the 16-bit and  32-bit  libraries.  This  page
+       describes what is different when you use the 32-bit library.
+
+       WARNING:  A  single  application  can  be linked with all or any of the
+       three libraries, but you must take care when processing any  particular
+       pattern  to  use  functions  from just one library. For example, if you
+       want to study a pattern that was compiled  with  pcre32_compile(),  you
+       must do so with pcre32_study(), not pcre_study(), and you must free the
+       study data with pcre32_free_study().
+
+
+THE HEADER FILE
+
+       There is only one header file, pcre.h. It contains prototypes  for  all
+       the functions in all libraries, as well as definitions of flags, struc-
+       tures, error codes, etc.
+
+
+THE LIBRARY NAME
+
+       In Unix-like systems, the 32-bit library is called libpcre32,  and  can
+       normally  be  accesss  by adding -lpcre32 to the command for linking an
+       application that uses PCRE.
+
+
+STRING TYPES
+
+       In the 8-bit library, strings are passed to PCRE library  functions  as
+       vectors  of  bytes  with  the  C  type "char *". In the 32-bit library,
+       strings are passed as vectors of unsigned 32-bit quantities. The  macro
+       PCRE_UCHAR32  specifies  an  appropriate  data type, and PCRE_SPTR32 is
+       defined as "const PCRE_UCHAR32 *". In very many environments, "unsigned
+       int" is a 32-bit data type. When PCRE is built, it defines PCRE_UCHAR32
+       as "unsigned int", but checks that it really is a 32-bit data type.  If
+       it is not, the build fails with an error message telling the maintainer
+       to modify the definition appropriately.
+
+
+STRUCTURE TYPES
+
+       The types of the opaque structures that are used  for  compiled  32-bit
+       patterns  and  JIT stacks are pcre32 and pcre32_jit_stack respectively.
+       The  type  of  the  user-accessible  structure  that  is  returned   by
+       pcre32_study()  is  pcre32_extra, and the type of the structure that is
+       used for passing data to a callout  function  is  pcre32_callout_block.
+       These structures contain the same fields, with the same names, as their
+       8-bit counterparts. The only difference is that pointers  to  character
+       strings are 32-bit instead of 8-bit types.
+
+
+32-BIT FUNCTIONS
+
+       For  every function in the 8-bit library there is a corresponding func-
+       tion in the 32-bit library with a name that starts with pcre32_ instead
+       of  pcre_.  The  prototypes are listed above. In addition, there is one
+       extra function, pcre32_utf32_to_host_byte_order(). This  is  a  utility
+       function  that converts a UTF-32 character string to host byte order if
+       necessary. The other 32-bit  functions  expect  the  strings  they  are
+       passed to be in host byte order.
+
+       The input and output arguments of pcre32_utf32_to_host_byte_order() may
+       point to the same address, that is, conversion in place  is  supported.
+       The output buffer must be at least as long as the input.
+
+       The  length  argument  specifies the number of 32-bit data units in the
+       input string; a negative value specifies a zero-terminated string.
+
+       If byte_order is NULL, it is assumed that the string starts off in host
+       byte  order. This may be changed by byte-order marks (BOMs) anywhere in
+       the string (commonly as the first character).
+
+       If byte_order is not NULL, a non-zero value of the integer to which  it
+       points  means  that  the input starts off in host byte order, otherwise
+       the opposite order is assumed. Again, BOMs in  the  string  can  change
+       this. The final byte order is passed back at the end of processing.
+
+       If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
+       copied into the output string. Otherwise they are discarded.
+
+       The result of the function is the number of 32-bit  units  placed  into
+       the  output  buffer,  including  the  zero terminator if the string was
+       zero-terminated.
+
+
+SUBJECT STRING OFFSETS
+
+       The lengths and starting offsets of subject strings must  be  specified
+       in  32-bit  data units, and the offsets within subject strings that are
+       returned by the matching functions are in also 32-bit units rather than
+       bytes.
+
+
+NAMED SUBPATTERNS
+
+       The  name-to-number translation table that is maintained for named sub-
+       patterns uses 32-bit characters.  The  pcre32_get_stringtable_entries()
+       function returns the length of each entry in the table as the number of
+       32-bit data units.
+
+
+OPTION NAMES
+
+       There   are   two   new   general   option   names,   PCRE_UTF32    and
+       PCRE_NO_UTF32_CHECK,     which     correspond    to    PCRE_UTF8    and
+       PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
+       define  the  same bits in the options word. There is a discussion about
+       the validity of UTF-32 strings in the pcreunicode page.
+
+       For the pcre32_config() function there is an  option  PCRE_CONFIG_UTF32
+       that  returns  1  if UTF-32 support is configured, otherwise 0. If this
+       option  is  given  to  pcre_config()  or  pcre16_config(),  or  if  the
+       PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF16  option is given to pcre32_con-
+       fig(), the result is the PCRE_ERROR_BADOPTION error.
+
+
+CHARACTER CODES
+
+       In 32-bit mode, when  PCRE_UTF32  is  not  set,  character  values  are
+       treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
+       that they can range from 0 to 0x7fffffff instead of 0 to 0xff.  Charac-
+       ter  types for characters less than 0xff can therefore be influenced by
+       the locale in the same way as before.   Characters  greater  than  0xff
+       have only one case, and no "type" (such as letter or digit).
+
+       In  UTF-32  mode,  the  character  code  is  Unicode, in the range 0 to
+       0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
+       because those are "surrogate" values that are ill-formed in UTF-32.
+
+       A  UTF-32 string can indicate its endianness by special code knows as a
+       byte-order mark (BOM). The PCRE functions do not handle this, expecting
+       strings   to   be  in  host  byte  order.  A  utility  function  called
+       pcre32_utf32_to_host_byte_order() is provided to help  with  this  (see
+       above).
+
+
+ERROR NAMES
+
+       The  error  PCRE_ERROR_BADUTF32  corresponds  to its 8-bit counterpart.
+       The error PCRE_ERROR_BADMODE is given when a compiled pattern is passed
+       to  a  function that processes patterns in the other mode, for example,
+       if a pattern compiled with pcre_compile() is passed to pcre32_exec().
+
+       There are new error codes whose names  begin  with  PCRE_UTF32_ERR  for
+       invalid  UTF-32  strings,  corresponding to the PCRE_UTF8_ERR codes for
+       UTF-8 strings that are described in the section entitled "Reason  codes
+       for  invalid UTF-8 strings" in the main pcreapi page. The UTF-32 errors
+       are:
+
+         PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
+         PCRE_UTF32_ERR2  Non-character
+         PCRE_UTF32_ERR3  Character > 0x10ffff
+
+
+ERROR TEXTS
+
+       If there is an error while compiling a pattern, the error text that  is
+       passed  back by pcre32_compile() or pcre32_compile2() is still an 8-bit
+       character string, zero-terminated.
+
+
+CALLOUTS
+
+       The subject and mark fields in the callout block that is  passed  to  a
+       callout function point to 32-bit vectors.
+
+
+TESTING
+
+       The  pcretest  program continues to operate with 8-bit input and output
+       files, but it can be used for testing the 32-bit library. If it is  run
+       with the command line option -32, patterns and subject strings are con-
+       verted from 8-bit to 32-bit before being passed to PCRE, and the 32-bit
+       library  functions  are used instead of the 8-bit ones. Returned 32-bit
+       strings are converted to 8-bit for output. If both the  8-bit  and  the
+       16-bit libraries were not compiled, pcretest defaults to 32-bit and the
+       -32 option is ignored.
+
+       When PCRE is being built, the RunTest script that is  called  by  "make
+       check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
+       16-bit and 32-bit libraries has been built, and runs the  tests  appro-
+       priately.
+
+
+NOT SUPPORTED IN 32-BIT MODE
+
+       Not all the features of the 8-bit library are available with the 32-bit
+       library. The C++ and POSIX wrapper functions  support  only  the  8-bit
+       library, and the pcregrep program is at present 8-bit only.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 12 May 2013
+       Copyright (c) 1997-2013 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCREBUILD(3)               Library Functions Manual               PCREBUILD(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+BUILDING PCRE
+
+       PCRE  is  distributed with a configure script that can be used to build
+       the library in Unix-like environments using the applications  known  as
+       Autotools.   Also  in  the  distribution  are files to support building
+       using CMake instead of configure. The text file README contains general
+       information  about  building  with Autotools (some of which is repeated
+       below), and also has some comments about building on various  operating
+       systems.  There  is  a lot more information about building PCRE without
+       using Autotools (including information about using CMake  and  building
+       "by  hand")  in  the  text file called NON-AUTOTOOLS-BUILD.  You should
+       consult this file as well as the README file if you are building  in  a
+       non-Unix-like environment.
+
+
+PCRE BUILD-TIME OPTIONS
+
+       The  rest of this document describes the optional features of PCRE that
+       can be selected when the library is compiled. It  assumes  use  of  the
+       configure  script,  where  the  optional features are selected or dese-
+       lected by providing options to configure before running the  make  com-
+       mand.  However,  the same options can be selected in both Unix-like and
+       non-Unix-like environments using the GUI facility of cmake-gui  if  you
+       are using CMake instead of configure to build PCRE.
+
+       If  you  are not using Autotools or CMake, option selection can be done
+       by editing the config.h file, or by passing parameter settings  to  the
+       compiler, as described in NON-AUTOTOOLS-BUILD.
+
+       The complete list of options for configure (which includes the standard
+       ones such as the  selection  of  the  installation  directory)  can  be
+       obtained by running
+
+         ./configure --help
+
+       The  following  sections  include  descriptions  of options whose names
+       begin with --enable or --disable. These settings specify changes to the
+       defaults  for  the configure command. Because of the way that configure
+       works, --enable and --disable always come in pairs, so  the  complemen-
+       tary  option always exists as well, but as it specifies the default, it
+       is not described.
+
+
+BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
+
+       By default, a library called libpcre  is  built,  containing  functions
+       that  take  string  arguments  contained in vectors of bytes, either as
+       single-byte characters, or interpreted as UTF-8 strings. You  can  also
+       build  a  separate library, called libpcre16, in which strings are con-
+       tained in vectors of 16-bit data units and interpreted either  as  sin-
+       gle-unit characters or UTF-16 strings, by adding
+
+         --enable-pcre16
+
+       to  the  configure  command.  You  can  also build yet another separate
+       library, called libpcre32, in which strings are contained in vectors of
+       32-bit  data  units and interpreted either as single-unit characters or
+       UTF-32 strings, by adding
+
+         --enable-pcre32
+
+       to the configure command. If you do not want the 8-bit library, add
+
+         --disable-pcre8
+
+       as well. At least one of the three libraries must be built.  Note  that
+       the  C++  and  POSIX  wrappers are for the 8-bit library only, and that
+       pcregrep is an 8-bit program. None of these are  built  if  you  select
+       only the 16-bit or 32-bit libraries.
+
+
+BUILDING SHARED AND STATIC LIBRARIES
+
+       The  Autotools  PCRE building process uses libtool to build both shared
+       and static libraries by default. You  can  suppress  one  of  these  by
+       adding one of
+
+         --disable-shared
+         --disable-static
+
+       to the configure command, as required.
+
+
+C++ SUPPORT
+
+       By  default,  if the 8-bit library is being built, the configure script
+       will search for a C++ compiler and C++ header files. If it finds  them,
+       it  automatically  builds  the C++ wrapper library (which supports only
+       8-bit strings). You can disable this by adding
+
+         --disable-cpp
+
+       to the configure command.
+
+
+UTF-8, UTF-16 AND UTF-32 SUPPORT
+
+       To build PCRE with support for UTF Unicode character strings, add
+
+         --enable-utf
+
+       to the configure command. This setting applies to all three  libraries,
+       adding  support  for  UTF-8 to the 8-bit library, support for UTF-16 to
+       the 16-bit library, and  support  for  UTF-32  to  the  to  the  32-bit
+       library.  There  are no separate options for enabling UTF-8, UTF-16 and
+       UTF-32 independently because that would allow ridiculous settings  such
+       as  requesting UTF-16 support while building only the 8-bit library. It
+       is not possible to build one library with UTF support and another with-
+       out  in the same configuration. (For backwards compatibility, --enable-
+       utf8 is a synonym of --enable-utf.)
+
+       Of itself, this setting does not make  PCRE  treat  strings  as  UTF-8,
+       UTF-16  or UTF-32. As well as compiling PCRE with this option, you also
+       have have to set the PCRE_UTF8, PCRE_UTF16  or  PCRE_UTF32  option  (as
+       appropriate) when you call one of the pattern compiling functions.
+
+       If  you  set --enable-utf when compiling in an EBCDIC environment, PCRE
+       expects its input to be either ASCII or UTF-8 (depending  on  the  run-
+       time option). It is not possible to support both EBCDIC and UTF-8 codes
+       in the same version of  the  library.  Consequently,  --enable-utf  and
+       --enable-ebcdic are mutually exclusive.
+
+
+UNICODE CHARACTER PROPERTY SUPPORT
+
+       UTF  support allows the libraries to process character codepoints up to
+       0x10ffff in the strings that they handle. On its own, however, it  does
+       not provide any facilities for accessing the properties of such charac-
+       ters. If you want to be able to use the pattern escapes \P, \p, and \X,
+       which refer to Unicode character properties, you must add
+
+         --enable-unicode-properties
+
+       to  the  configure  command. This implies UTF support, even if you have
+       not explicitly requested it.
+
+       Including Unicode property support adds around 30K  of  tables  to  the
+       PCRE  library.  Only  the general category properties such as Lu and Nd
+       are supported. Details are given in the pcrepattern documentation.
+
+
+JUST-IN-TIME COMPILER SUPPORT
+
+       Just-in-time compiler support is included in the build by specifying
+
+         --enable-jit
+
+       This support is available only for certain hardware  architectures.  If
+       this  option  is  set  for  an unsupported architecture, a compile time
+       error occurs.  See the pcrejit documentation for a  discussion  of  JIT
+       usage. When JIT support is enabled, pcregrep automatically makes use of
+       it, unless you add
+
+         --disable-pcregrep-jit
+
+       to the "configure" command.
+
+
+CODE VALUE OF NEWLINE
+
+       By default, PCRE interprets the linefeed (LF) character  as  indicating
+       the  end  of  a line. This is the normal newline character on Unix-like
+       systems. You can compile PCRE to use carriage return (CR)  instead,  by
+       adding
+
+         --enable-newline-is-cr
+
+       to  the  configure  command.  There  is  also  a --enable-newline-is-lf
+       option, which explicitly specifies linefeed as the newline character.
+
+       Alternatively, you can specify that line endings are to be indicated by
+       the two character sequence CRLF. If you want this, add
+
+         --enable-newline-is-crlf
+
+       to the configure command. There is a fourth option, specified by
+
+         --enable-newline-is-anycrlf
+
+       which  causes  PCRE  to recognize any of the three sequences CR, LF, or
+       CRLF as indicating a line ending. Finally, a fifth option, specified by
+
+         --enable-newline-is-any
+
+       causes PCRE to recognize any Unicode newline sequence.
+
+       Whatever line ending convention is selected when PCRE is built  can  be
+       overridden  when  the library functions are called. At build time it is
+       conventional to use the standard for your operating system.
+
+
+WHAT \R MATCHES
+
+       By default, the sequence \R in a pattern matches  any  Unicode  newline
+       sequence,  whatever  has  been selected as the line ending sequence. If
+       you specify
+
+         --enable-bsr-anycrlf
+
+       the default is changed so that \R matches only CR, LF, or  CRLF.  What-
+       ever  is selected when PCRE is built can be overridden when the library
+       functions are called.
+
+
+POSIX MALLOC USAGE
+
+       When the 8-bit library is called through the POSIX interface  (see  the
+       pcreposix  documentation),  additional  working storage is required for
+       holding the pointers to capturing  substrings,  because  PCRE  requires
+       three integers per substring, whereas the POSIX interface provides only
+       two. If the number of expected substrings is small, the  wrapper  func-
+       tion  uses  space  on the stack, because this is faster than using mal-
+       loc() for each call. The default threshold above which the stack is  no
+       longer used is 10; it can be changed by adding a setting such as
+
+         --with-posix-malloc-threshold=20
+
+       to the configure command.
+
+
+HANDLING VERY LARGE PATTERNS
+
+       Within  a  compiled  pattern,  offset values are used to point from one
+       part to another (for example, from an opening parenthesis to an  alter-
+       nation  metacharacter).  By default, in the 8-bit and 16-bit libraries,
+       two-byte values are used for these offsets, leading to a  maximum  size
+       for  a compiled pattern of around 64K. This is sufficient to handle all
+       but the most gigantic patterns.  Nevertheless, some people do  want  to
+       process  truly  enormous patterns, so it is possible to compile PCRE to
+       use three-byte or four-byte offsets by adding a setting such as
+
+         --with-link-size=3
+
+       to the configure command. The value given must be 2, 3, or 4.  For  the
+       16-bit  library,  a  value of 3 is rounded up to 4. In these libraries,
+       using longer offsets slows down the operation of PCRE because it has to
+       load  additional  data  when  handling them. For the 32-bit library the
+       value is always 4 and cannot be overridden; the value  of  --with-link-
+       size is ignored.
+
+
+AVOIDING EXCESSIVE STACK USAGE
+
+       When matching with the pcre_exec() function, PCRE implements backtrack-
+       ing by making recursive calls to an internal function  called  match().
+       In  environments  where  the size of the stack is limited, this can se-
+       verely limit PCRE's operation. (The Unix environment does  not  usually
+       suffer from this problem, but it may sometimes be necessary to increase
+       the maximum stack size.  There is a discussion in the  pcrestack  docu-
+       mentation.)  An alternative approach to recursion that uses memory from
+       the heap to remember data, instead of using recursive  function  calls,
+       has  been  implemented to work round the problem of limited stack size.
+       If you want to build a version of PCRE that works this way, add
+
+         --disable-stack-for-recursion
+
+       to the configure command. With this configuration, PCRE  will  use  the
+       pcre_stack_malloc  and pcre_stack_free variables to call memory manage-
+       ment functions. By default these point to malloc() and free(), but  you
+       can replace the pointers so that your own functions are used instead.
+
+       Separate  functions  are  provided  rather  than  using pcre_malloc and
+       pcre_free because the  usage  is  very  predictable:  the  block  sizes
+       requested  are  always  the  same,  and  the blocks are always freed in
+       reverse order. A calling program might be able to  implement  optimized
+       functions  that  perform  better  than  malloc()  and free(). PCRE runs
+       noticeably more slowly when built in this way. This option affects only
+       the pcre_exec() function; it is not relevant for pcre_dfa_exec().
+
+
+LIMITING PCRE RESOURCE USAGE
+
+       Internally,  PCRE has a function called match(), which it calls repeat-
+       edly  (sometimes  recursively)  when  matching  a  pattern   with   the
+       pcre_exec()  function.  By controlling the maximum number of times this
+       function may be called during a single matching operation, a limit  can
+       be  placed  on  the resources used by a single call to pcre_exec(). The
+       limit can be changed at run time, as described in the pcreapi  documen-
+       tation.  The default is 10 million, but this can be changed by adding a
+       setting such as
+
+         --with-match-limit=500000
+
+       to  the  configure  command.  This  setting  has  no  effect   on   the
+       pcre_dfa_exec() matching function.
+
+       In  some  environments  it is desirable to limit the depth of recursive
+       calls of match() more strictly than the total number of calls, in order
+       to  restrict  the maximum amount of stack (or heap, if --disable-stack-
+       for-recursion is specified) that is used. A second limit controls this;
+       it  defaults  to  the  value  that is set for --with-match-limit, which
+       imposes no additional constraints. However, you can set a  lower  limit
+       by adding, for example,
+
+         --with-match-limit-recursion=10000
+
+       to  the  configure  command.  This  value can also be overridden at run
+       time.
+
+
+CREATING CHARACTER TABLES AT BUILD TIME
+
+       PCRE uses fixed tables for processing characters whose code values  are
+       less  than 256. By default, PCRE is built with a set of tables that are
+       distributed in the file pcre_chartables.c.dist. These  tables  are  for
+       ASCII codes only. If you add
+
+         --enable-rebuild-chartables
+
+       to  the  configure  command, the distributed tables are no longer used.
+       Instead, a program called dftables is compiled and  run.  This  outputs
+       the source for new set of tables, created in the default locale of your
+       C run-time system. (This method of replacing the tables does  not  work
+       if  you are cross compiling, because dftables is run on the local host.
+       If you need to create alternative tables when cross compiling, you will
+       have to do so "by hand".)
+
+
+USING EBCDIC CODE
+
+       PCRE  assumes  by  default that it will run in an environment where the
+       character code is ASCII (or Unicode, which is  a  superset  of  ASCII).
+       This  is  the  case for most computer operating systems. PCRE can, how-
+       ever, be compiled to run in an EBCDIC environment by adding
+
+         --enable-ebcdic
+
+       to the configure command. This setting implies --enable-rebuild-charta-
+       bles.  You  should  only  use  it if you know that you are in an EBCDIC
+       environment (for example,  an  IBM  mainframe  operating  system).  The
+       --enable-ebcdic option is incompatible with --enable-utf.
+
+       The EBCDIC character that corresponds to an ASCII LF is assumed to have
+       the value 0x15 by default. However, in some EBCDIC  environments,  0x25
+       is used. In such an environment you should use
+
+         --enable-ebcdic-nl25
+
+       as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
+       has the same value as in ASCII, namely, 0x0d.  Whichever  of  0x15  and
+       0x25 is not chosen as LF is made to correspond to the Unicode NEL char-
+       acter (which, in Unicode, is 0x85).
+
+       The options that select newline behaviour, such as --enable-newline-is-
+       cr, and equivalent run-time options, refer to these character values in
+       an EBCDIC environment.
+
+
+PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
+
+       By default, pcregrep reads all files as plain text. You can build it so
+       that it recognizes files whose names end in .gz or .bz2, and reads them
+       with libz or libbz2, respectively, by adding one or both of
+
+         --enable-pcregrep-libz
+         --enable-pcregrep-libbz2
+
+       to the configure command. These options naturally require that the rel-
+       evant  libraries  are installed on your system. Configuration will fail
+       if they are not.
+
+
+PCREGREP BUFFER SIZE
+
+       pcregrep uses an internal buffer to hold a "window" on the file  it  is
+       scanning, in order to be able to output "before" and "after" lines when
+       it finds a match. The size of the buffer is controlled by  a  parameter
+       whose default value is 20K. The buffer itself is three times this size,
+       but because of the way it is used for holding "before" lines, the long-
+       est  line  that  is guaranteed to be processable is the parameter size.
+       You can change the default parameter value by adding, for example,
+
+         --with-pcregrep-bufsize=50K
+
+       to the configure command. The caller of pcregrep can, however, override
+       this value by specifying a run-time option.
+
+
+PCRETEST OPTION FOR LIBREADLINE SUPPORT
+
+       If you add
+
+         --enable-pcretest-libreadline
+
+       to  the  configure  command,  pcretest  is  linked with the libreadline
+       library, and when its input is from a terminal, it reads it  using  the
+       readline() function. This provides line-editing and history facilities.
+       Note that libreadline is GPL-licensed, so if you distribute a binary of
+       pcretest linked in this way, there may be licensing issues.
+
+       Setting  this  option  causes  the -lreadline option to be added to the
+       pcretest build. In many operating environments with  a  sytem-installed
+       libreadline this is sufficient. However, in some environments (e.g.  if
+       an unmodified distribution version of readline is in use),  some  extra
+       configuration  may  be necessary. The INSTALL file for libreadline says
+       this:
+
+         "Readline uses the termcap functions, but does not link with the
+         termcap or curses library itself, allowing applications which link
+         with readline the to choose an appropriate library."
+
+       If your environment has not been set up so that an appropriate  library
+       is automatically included, you may need to add something like
+
+         LIBS="-ncurses"
+
+       immediately before the configure command.
+
+
+DEBUGGING WITH VALGRIND SUPPORT
+
+       By adding the
+
+         --enable-valgrind
+
+       option  to to the configure command, PCRE will use valgrind annotations
+       to mark certain memory regions as  unaddressable.  This  allows  it  to
+       detect invalid memory accesses, and is mostly useful for debugging PCRE
+       itself.
+
+
+CODE COVERAGE REPORTING
+
+       If your C compiler is gcc, you can build a version  of  PCRE  that  can
+       generate a code coverage report for its test suite. To enable this, you
+       must install lcov version 1.6 or above. Then specify
+
+         --enable-coverage
+
+       to the configure command and build PCRE in the usual way.
+
+       Note that using ccache (a caching C compiler) is incompatible with code
+       coverage  reporting. If you have configured ccache to run automatically
+       on your system, you must set the environment variable
+
+         CCACHE_DISABLE=1
+
+       before running make to build PCRE, so that ccache is not used.
+
+       When --enable-coverage is used,  the  following  addition  targets  are
+       added to the Makefile:
+
+         make coverage
+
+       This  creates  a  fresh  coverage report for the PCRE test suite. It is
+       equivalent to running "make coverage-reset", "make  coverage-baseline",
+       "make check", and then "make coverage-report".
+
+         make coverage-reset
+
+       This zeroes the coverage counters, but does nothing else.
+
+         make coverage-baseline
+
+       This captures baseline coverage information.
+
+         make coverage-report
+
+       This creates the coverage report.
+
+         make coverage-clean-report
+
+       This  removes the generated coverage report without cleaning the cover-
+       age data itself.
+
+         make coverage-clean-data
+
+       This removes the captured coverage data without removing  the  coverage
+       files created at compile time (*.gcno).
+
+         make coverage-clean
+
+       This  cleans all coverage data including the generated coverage report.
+       For more information about code coverage, see the gcov and  lcov  docu-
+       mentation.
+
+
+SEE ALSO
+
+       pcreapi(3), pcre16, pcre32, pcre_config(3).
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 12 May 2013
+       Copyright (c) 1997-2013 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCREMATCHING(3)            Library Functions Manual            PCREMATCHING(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+PCRE MATCHING ALGORITHMS
+
+       This document describes the two different algorithms that are available
+       in PCRE for matching a compiled regular expression against a given sub-
+       ject  string.  The  "standard"  algorithm  is  the  one provided by the
+       pcre_exec(), pcre16_exec() and pcre32_exec() functions. These  work  in
+       the  same as as Perl's matching function, and provide a Perl-compatible
+       matching  operation.   The  just-in-time  (JIT)  optimization  that  is
+       described  in  the pcrejit documentation is compatible with these func-
+       tions.
+
+       An  alternative  algorithm  is   provided   by   the   pcre_dfa_exec(),
+       pcre16_dfa_exec()  and  pcre32_dfa_exec()  functions; they operate in a
+       different way, and are not Perl-compatible. This alternative has advan-
+       tages and disadvantages compared with the standard algorithm, and these
+       are described below.
+
+       When there is only one possible way in which a given subject string can
+       match  a pattern, the two algorithms give the same answer. A difference
+       arises, however, when there are multiple possibilities. For example, if
+       the pattern
+
+         ^<.*>
+
+       is matched against the string
+
+           
+
+       there are three possible answers. The standard algorithm finds only one
+       of them, whereas the alternative algorithm finds all three.
+
+
+REGULAR EXPRESSIONS AS TREES
+
+       The set of strings that are matched by a regular expression can be rep-
+       resented  as  a  tree structure. An unlimited repetition in the pattern
+       makes the tree of infinite size, but it is still a tree.  Matching  the
+       pattern  to a given subject string (from a given starting point) can be
+       thought of as a search of the tree.  There are two  ways  to  search  a
+       tree:  depth-first  and  breadth-first, and these correspond to the two
+       matching algorithms provided by PCRE.
+
+
+THE STANDARD MATCHING ALGORITHM
+
+       In the terminology of Jeffrey Friedl's book "Mastering Regular  Expres-
+       sions",  the  standard  algorithm  is an "NFA algorithm". It conducts a
+       depth-first search of the pattern tree. That is, it  proceeds  along  a
+       single path through the tree, checking that the subject matches what is
+       required. When there is a mismatch, the algorithm  tries  any  alterna-
+       tives  at  the  current point, and if they all fail, it backs up to the
+       previous branch point in the  tree,  and  tries  the  next  alternative
+       branch  at  that  level.  This often involves backing up (moving to the
+       left) in the subject string as well.  The  order  in  which  repetition
+       branches  are  tried  is controlled by the greedy or ungreedy nature of
+       the quantifier.
+
+       If a leaf node is reached, a matching string has  been  found,  and  at
+       that  point the algorithm stops. Thus, if there is more than one possi-
+       ble match, this algorithm returns the first one that it finds.  Whether
+       this  is the shortest, the longest, or some intermediate length depends
+       on the way the greedy and ungreedy repetition quantifiers are specified
+       in the pattern.
+
+       Because  it  ends  up  with a single path through the tree, it is rela-
+       tively straightforward for this algorithm to keep  track  of  the  sub-
+       strings  that  are  matched  by portions of the pattern in parentheses.
+       This provides support for capturing parentheses and back references.
+
+
+THE ALTERNATIVE MATCHING ALGORITHM
+
+       This algorithm conducts a breadth-first search of  the  tree.  Starting
+       from  the  first  matching  point  in the subject, it scans the subject
+       string from left to right, once, character by character, and as it does
+       this,  it remembers all the paths through the tree that represent valid
+       matches. In Friedl's terminology, this is a kind  of  "DFA  algorithm",
+       though  it is not implemented as a traditional finite state machine (it
+       keeps multiple states active simultaneously).
+
+       Although the general principle of this matching algorithm  is  that  it
+       scans  the subject string only once, without backtracking, there is one
+       exception: when a lookaround assertion is encountered,  the  characters
+       following  or  preceding  the  current  point  have to be independently
+       inspected.
+
+       The scan continues until either the end of the subject is  reached,  or
+       there  are  no more unterminated paths. At this point, terminated paths
+       represent the different matching possibilities (if there are none,  the
+       match  has  failed).   Thus,  if there is more than one possible match,
+       this algorithm finds all of them, and in particular, it finds the long-
+       est.  The  matches are returned in decreasing order of length. There is
+       an option to stop the algorithm after the first match (which is  neces-
+       sarily the shortest) is found.
+
+       Note that all the matches that are found start at the same point in the
+       subject. If the pattern
+
+         cat(er(pillar)?)?
+
+       is matched against the string "the caterpillar catchment",  the  result
+       will  be the three strings "caterpillar", "cater", and "cat" that start
+       at the fifth character of the subject. The algorithm does not automati-
+       cally move on to find matches that start at later positions.
+
+       PCRE's  "auto-possessification" optimization usually applies to charac-
+       ter repeats at the end of a pattern (as well as internally). For  exam-
+       ple, the pattern "a\d+" is compiled as if it were "a\d++" because there
+       is no point even considering the possibility of backtracking  into  the
+       repeated  digits.  For  DFA matching, this means that only one possible
+       match is found. If you really do want multiple matches in  such  cases,
+       either use an ungreedy repeat ("a\d+?") or set the PCRE_NO_AUTO_POSSESS
+       option when compiling.
+
+       There are a number of features of PCRE regular expressions that are not
+       supported by the alternative matching algorithm. They are as follows:
+
+       1.  Because  the  algorithm  finds  all possible matches, the greedy or
+       ungreedy nature of repetition quantifiers is not relevant.  Greedy  and
+       ungreedy quantifiers are treated in exactly the same way. However, pos-
+       sessive quantifiers can make a difference when what follows could  also
+       match what is quantified, for example in a pattern like this:
+
+         ^a++\w!
+
+       This  pattern matches "aaab!" but not "aaa!", which would be matched by
+       a non-possessive quantifier. Similarly, if an atomic group is  present,
+       it  is matched as if it were a standalone pattern at the current point,
+       and the longest match is then "locked in" for the rest of  the  overall
+       pattern.
+
+       2. When dealing with multiple paths through the tree simultaneously, it
+       is not straightforward to keep track of  captured  substrings  for  the
+       different  matching  possibilities,  and  PCRE's implementation of this
+       algorithm does not attempt to do this. This means that no captured sub-
+       strings are available.
+
+       3.  Because no substrings are captured, back references within the pat-
+       tern are not supported, and cause errors if encountered.
+
+       4. For the same reason, conditional expressions that use  a  backrefer-
+       ence  as  the  condition or test for a specific group recursion are not
+       supported.
+
+       5. Because many paths through the tree may be  active,  the  \K  escape
+       sequence, which resets the start of the match when encountered (but may
+       be on some paths and not on others), is not  supported.  It  causes  an
+       error if encountered.
+
+       6.  Callouts  are  supported, but the value of the capture_top field is
+       always 1, and the value of the capture_last field is always -1.
+
+       7. The \C escape sequence, which (in  the  standard  algorithm)  always
+       matches  a  single data unit, even in UTF-8, UTF-16 or UTF-32 modes, is
+       not supported in these modes, because the alternative  algorithm  moves
+       through the subject string one character (not data unit) at a time, for
+       all active paths through the tree.
+
+       8. Except for (*FAIL), the backtracking control verbs such as  (*PRUNE)
+       are  not  supported.  (*FAIL)  is supported, and behaves like a failing
+       negative assertion.
+
+
+ADVANTAGES OF THE ALTERNATIVE ALGORITHM
+
+       Using the alternative matching algorithm provides the following  advan-
+       tages:
+
+       1. All possible matches (at a single point in the subject) are automat-
+       ically found, and in particular, the longest match is  found.  To  find
+       more than one match using the standard algorithm, you have to do kludgy
+       things with callouts.
+
+       2. Because the alternative algorithm  scans  the  subject  string  just
+       once, and never needs to backtrack (except for lookbehinds), it is pos-
+       sible to pass very long subject strings to  the  matching  function  in
+       several pieces, checking for partial matching each time. Although it is
+       possible to do multi-segment matching using the standard  algorithm  by
+       retaining  partially  matched  substrings,  it is more complicated. The
+       pcrepartial documentation gives details of partial  matching  and  dis-
+       cusses multi-segment matching.
+
+
+DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
+
+       The alternative algorithm suffers from a number of disadvantages:
+
+       1.  It  is  substantially  slower  than the standard algorithm. This is
+       partly because it has to search for all possible matches, but  is  also
+       because it is less susceptible to optimization.
+
+       2. Capturing parentheses and back references are not supported.
+
+       3. Although atomic groups are supported, their use does not provide the
+       performance advantage that it does for the standard algorithm.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 12 November 2013
+       Copyright (c) 1997-2012 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCREAPI(3)                 Library Functions Manual                 PCREAPI(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+       #include 
+
+
+PCRE NATIVE API BASIC FUNCTIONS
+
+       pcre *pcre_compile(const char *pattern, int options,
+            const char **errptr, int *erroffset,
+            const unsigned char *tableptr);
+
+       pcre *pcre_compile2(const char *pattern, int options,
+            int *errorcodeptr,
+            const char **errptr, int *erroffset,
+            const unsigned char *tableptr);
+
+       pcre_extra *pcre_study(const pcre *code, int options,
+            const char **errptr);
+
+       void pcre_free_study(pcre_extra *extra);
+
+       int pcre_exec(const pcre *code, const pcre_extra *extra,
+            const char *subject, int length, int startoffset,
+            int options, int *ovector, int ovecsize);
+
+       int pcre_dfa_exec(const pcre *code, const pcre_extra *extra,
+            const char *subject, int length, int startoffset,
+            int options, int *ovector, int ovecsize,
+            int *workspace, int wscount);
+
+
+PCRE NATIVE API STRING EXTRACTION FUNCTIONS
+
+       int pcre_copy_named_substring(const pcre *code,
+            const char *subject, int *ovector,
+            int stringcount, const char *stringname,
+            char *buffer, int buffersize);
+
+       int pcre_copy_substring(const char *subject, int *ovector,
+            int stringcount, int stringnumber, char *buffer,
+            int buffersize);
+
+       int pcre_get_named_substring(const pcre *code,
+            const char *subject, int *ovector,
+            int stringcount, const char *stringname,
+            const char **stringptr);
+
+       int pcre_get_stringnumber(const pcre *code,
+            const char *name);
+
+       int pcre_get_stringtable_entries(const pcre *code,
+            const char *name, char **first, char **last);
+
+       int pcre_get_substring(const char *subject, int *ovector,
+            int stringcount, int stringnumber,
+            const char **stringptr);
+
+       int pcre_get_substring_list(const char *subject,
+            int *ovector, int stringcount, const char ***listptr);
+
+       void pcre_free_substring(const char *stringptr);
+
+       void pcre_free_substring_list(const char **stringptr);
+
+
+PCRE NATIVE API AUXILIARY FUNCTIONS
+
+       int pcre_jit_exec(const pcre *code, const pcre_extra *extra,
+            const char *subject, int length, int startoffset,
+            int options, int *ovector, int ovecsize,
+            pcre_jit_stack *jstack);
+
+       pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
+
+       void pcre_jit_stack_free(pcre_jit_stack *stack);
+
+       void pcre_assign_jit_stack(pcre_extra *extra,
+            pcre_jit_callback callback, void *data);
+
+       const unsigned char *pcre_maketables(void);
+
+       int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
+            int what, void *where);
+
+       int pcre_refcount(pcre *code, int adjust);
+
+       int pcre_config(int what, void *where);
+
+       const char *pcre_version(void);
+
+       int pcre_pattern_to_host_byte_order(pcre *code,
+            pcre_extra *extra, const unsigned char *tables);
+
+
+PCRE NATIVE API INDIRECTED FUNCTIONS
+
+       void *(*pcre_malloc)(size_t);
+
+       void (*pcre_free)(void *);
+
+       void *(*pcre_stack_malloc)(size_t);
+
+       void (*pcre_stack_free)(void *);
+
+       int (*pcre_callout)(pcre_callout_block *);
+
+       int (*pcre_stack_guard)(void);
+
+
+PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES
+
+       As  well  as  support  for  8-bit character strings, PCRE also supports
+       16-bit strings (from release 8.30) and  32-bit  strings  (from  release
+       8.32),  by means of two additional libraries. They can be built as well
+       as, or instead of, the 8-bit library. To avoid too  much  complication,
+       this  document describes the 8-bit versions of the functions, with only
+       occasional references to the 16-bit and 32-bit libraries.
+
+       The 16-bit and 32-bit functions operate in the same way as their  8-bit
+       counterparts;  they  just  use different data types for their arguments
+       and results, and their names start with pcre16_ or pcre32_  instead  of
+       pcre_.  For  every  option  that  has  UTF8  in  its name (for example,
+       PCRE_UTF8), there are corresponding 16-bit and 32-bit names  with  UTF8
+       replaced by UTF16 or UTF32, respectively. This facility is in fact just
+       cosmetic; the 16-bit and 32-bit option names define the same  bit  val-
+       ues.
+
+       References to bytes and UTF-8 in this document should be read as refer-
+       ences to 16-bit data units and UTF-16 when using the 16-bit library, or
+       32-bit  data  units  and  UTF-32  when using the 32-bit library, unless
+       specified otherwise.  More details of the specific differences for  the
+       16-bit and 32-bit libraries are given in the pcre16 and pcre32 pages.
+
+
+PCRE API OVERVIEW
+
+       PCRE has its own native API, which is described in this document. There
+       are also some wrapper functions (for the 8-bit library only) that  cor-
+       respond  to  the  POSIX  regular  expression  API, but they do not give
+       access to all the functionality. They are described  in  the  pcreposix
+       documentation.  Both  of these APIs define a set of C function calls. A
+       C++ wrapper (again for the 8-bit library only) is also distributed with
+       PCRE. It is documented in the pcrecpp page.
+
+       The  native  API  C  function prototypes are defined in the header file
+       pcre.h, and on Unix-like systems the (8-bit) library itself  is  called
+       libpcre.  It  can  normally be accessed by adding -lpcre to the command
+       for linking an application that uses PCRE. The header file defines  the
+       macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release
+       numbers for the library. Applications can use these to include  support
+       for different releases of PCRE.
+
+       In a Windows environment, if you want to statically link an application
+       program against a non-dll pcre.a  file,  you  must  define  PCRE_STATIC
+       before  including  pcre.h or pcrecpp.h, because otherwise the pcre_mal-
+       loc()   and   pcre_free()   exported   functions   will   be   declared
+       __declspec(dllimport), with unwanted results.
+
+       The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and
+       pcre_exec() are used for compiling and matching regular expressions  in
+       a  Perl-compatible  manner. A sample program that demonstrates the sim-
+       plest way of using them is provided in the file  called  pcredemo.c  in
+       the PCRE source distribution. A listing of this program is given in the
+       pcredemo documentation, and the pcresample documentation describes  how
+       to compile and run it.
+
+       Just-in-time  compiler  support is an optional feature of PCRE that can
+       be built in appropriate hardware environments. It greatly speeds up the
+       matching  performance  of  many  patterns.  Simple  programs can easily
+       request that it be used if available, by  setting  an  option  that  is
+       ignored  when  it is not relevant. More complicated programs might need
+       to    make    use    of    the    functions     pcre_jit_stack_alloc(),
+       pcre_jit_stack_free(),  and pcre_assign_jit_stack() in order to control
+       the JIT code's memory usage.
+
+       From release 8.32 there is also a direct interface for  JIT  execution,
+       which  gives  improved performance. The JIT-specific functions are dis-
+       cussed in the pcrejit documentation.
+
+       A second matching function, pcre_dfa_exec(), which is not Perl-compati-
+       ble,  is  also provided. This uses a different algorithm for the match-
+       ing. The alternative algorithm finds all possible matches (at  a  given
+       point  in  the  subject), and scans the subject just once (unless there
+       are lookbehind assertions). However, this  algorithm  does  not  return
+       captured  substrings.  A description of the two matching algorithms and
+       their advantages and disadvantages is given in the  pcrematching  docu-
+       mentation.
+
+       In  addition  to  the  main compiling and matching functions, there are
+       convenience functions for extracting captured substrings from a subject
+       string that is matched by pcre_exec(). They are:
+
+         pcre_copy_substring()
+         pcre_copy_named_substring()
+         pcre_get_substring()
+         pcre_get_named_substring()
+         pcre_get_substring_list()
+         pcre_get_stringnumber()
+         pcre_get_stringtable_entries()
+
+       pcre_free_substring() and pcre_free_substring_list() are also provided,
+       to free the memory used for extracted strings.
+
+       The function pcre_maketables() is used to  build  a  set  of  character
+       tables   in   the   current   locale  for  passing  to  pcre_compile(),
+       pcre_exec(), or pcre_dfa_exec(). This is an optional facility  that  is
+       provided  for  specialist  use.  Most  commonly,  no special tables are
+       passed, in which case internal tables that are generated when  PCRE  is
+       built are used.
+
+       The  function  pcre_fullinfo()  is used to find out information about a
+       compiled pattern. The function pcre_version() returns a  pointer  to  a
+       string containing the version of PCRE and its date of release.
+
+       The  function  pcre_refcount()  maintains  a  reference count in a data
+       block containing a compiled pattern. This is provided for  the  benefit
+       of object-oriented applications.
+
+       The  global  variables  pcre_malloc and pcre_free initially contain the
+       entry points of the standard malloc()  and  free()  functions,  respec-
+       tively. PCRE calls the memory management functions via these variables,
+       so a calling program can replace them if it  wishes  to  intercept  the
+       calls. This should be done before calling any PCRE functions.
+
+       The  global  variables  pcre_stack_malloc  and pcre_stack_free are also
+       indirections to memory management functions.  These  special  functions
+       are  used  only  when  PCRE is compiled to use the heap for remembering
+       data, instead of recursive function calls, when running the pcre_exec()
+       function.  See  the  pcrebuild  documentation  for details of how to do
+       this. It is a non-standard way of building PCRE, for  use  in  environ-
+       ments  that  have  limited stacks. Because of the greater use of memory
+       management, it runs more slowly. Separate  functions  are  provided  so
+       that  special-purpose  external  code  can  be used for this case. When
+       used, these functions are always called in a  stack-like  manner  (last
+       obtained,  first freed), and always for memory blocks of the same size.
+       There is a discussion about PCRE's stack usage in the  pcrestack  docu-
+       mentation.
+
+       The global variable pcre_callout initially contains NULL. It can be set
+       by the caller to a "callout" function, which PCRE  will  then  call  at
+       specified  points during a matching operation. Details are given in the
+       pcrecallout documentation.
+
+       The global variable pcre_stack_guard initially contains NULL. It can be
+       set  by  the  caller  to  a function that is called by PCRE whenever it
+       starts to compile a parenthesized part of a pattern.  When  parentheses
+       are nested, PCRE uses recursive function calls, which use up the system
+       stack. This function is provided so that applications  with  restricted
+       stacks  can  force a compilation error if the stack runs out. The func-
+       tion should return zero if all is well, or non-zero to force an error.
+
+
+NEWLINES
+
+       PCRE supports five different conventions for indicating line breaks  in
+       strings:  a  single  CR (carriage return) character, a single LF (line-
+       feed) character, the two-character sequence CRLF, any of the three pre-
+       ceding,  or any Unicode newline sequence. The Unicode newline sequences
+       are the three just mentioned, plus the single characters  VT  (vertical
+       tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
+       separator, U+2028), and PS (paragraph separator, U+2029).
+
+       Each of the first three conventions is used by at least  one  operating
+       system  as its standard newline sequence. When PCRE is built, a default
+       can be specified.  The default default is LF, which is the  Unix  stan-
+       dard.  When  PCRE  is run, the default can be overridden, either when a
+       pattern is compiled, or when it is matched.
+
+       At compile time, the newline convention can be specified by the options
+       argument  of  pcre_compile(), or it can be specified by special text at
+       the start of the pattern itself; this overrides any other settings. See
+       the pcrepattern page for details of the special character sequences.
+
+       In the PCRE documentation the word "newline" is used to mean "the char-
+       acter or pair of characters that indicate a line break". The choice  of
+       newline  convention  affects  the  handling of the dot, circumflex, and
+       dollar metacharacters, the handling of #-comments in /x mode, and, when
+       CRLF  is a recognized line ending sequence, the match position advance-
+       ment for a non-anchored pattern. There is more detail about this in the
+       section on pcre_exec() options below.
+
+       The  choice of newline convention does not affect the interpretation of
+       the \n or \r escape sequences, nor does  it  affect  what  \R  matches,
+       which is controlled in a similar way, but by separate options.
+
+
+MULTITHREADING
+
+       The  PCRE  functions  can be used in multi-threading applications, with
+       the  proviso  that  the  memory  management  functions  pointed  to  by
+       pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the
+       callout and stack-checking functions pointed  to  by  pcre_callout  and
+       pcre_stack_guard, are shared by all threads.
+
+       The  compiled form of a regular expression is not altered during match-
+       ing, so the same compiled pattern can safely be used by several threads
+       at once.
+
+       If  the just-in-time optimization feature is being used, it needs sepa-
+       rate memory stack areas for each thread. See the pcrejit  documentation
+       for more details.
+
+
+SAVING PRECOMPILED PATTERNS FOR LATER USE
+
+       The compiled form of a regular expression can be saved and re-used at a
+       later time, possibly by a different program, and even on a  host  other
+       than  the  one  on  which  it  was  compiled.  Details are given in the
+       pcreprecompile documentation,  which  includes  a  description  of  the
+       pcre_pattern_to_host_byte_order()  function. However, compiling a regu-
+       lar expression with one version of PCRE for use with a  different  ver-
+       sion is not guaranteed to work and may cause crashes.
+
+
+CHECKING BUILD-TIME OPTIONS
+
+       int pcre_config(int what, void *where);
+
+       The  function pcre_config() makes it possible for a PCRE client to dis-
+       cover which optional features have been compiled into the PCRE library.
+       The  pcrebuild documentation has more details about these optional fea-
+       tures.
+
+       The first argument for pcre_config() is an  integer,  specifying  which
+       information is required; the second argument is a pointer to a variable
+       into which the information is placed. The returned  value  is  zero  on
+       success,  or  the negative error code PCRE_ERROR_BADOPTION if the value
+       in the first argument is not recognized. The following  information  is
+       available:
+
+         PCRE_CONFIG_UTF8
+
+       The  output is an integer that is set to one if UTF-8 support is avail-
+       able; otherwise it is set to zero. This value should normally be  given
+       to the 8-bit version of this function, pcre_config(). If it is given to
+       the  16-bit  or  32-bit  version  of  this  function,  the  result   is
+       PCRE_ERROR_BADOPTION.
+
+         PCRE_CONFIG_UTF16
+
+       The output is an integer that is set to one if UTF-16 support is avail-
+       able; otherwise it is set to zero. This value should normally be  given
+       to the 16-bit version of this function, pcre16_config(). If it is given
+       to the 8-bit  or  32-bit  version  of  this  function,  the  result  is
+       PCRE_ERROR_BADOPTION.
+
+         PCRE_CONFIG_UTF32
+
+       The output is an integer that is set to one if UTF-32 support is avail-
+       able; otherwise it is set to zero. This value should normally be  given
+       to the 32-bit version of this function, pcre32_config(). If it is given
+       to the 8-bit  or  16-bit  version  of  this  function,  the  result  is
+       PCRE_ERROR_BADOPTION.
+
+         PCRE_CONFIG_UNICODE_PROPERTIES
+
+       The  output  is  an  integer  that is set to one if support for Unicode
+       character properties is available; otherwise it is set to zero.
+
+         PCRE_CONFIG_JIT
+
+       The output is an integer that is set to one if support for just-in-time
+       compiling is available; otherwise it is set to zero.
+
+         PCRE_CONFIG_JITTARGET
+
+       The  output is a pointer to a zero-terminated "const char *" string. If
+       JIT support is available, the string contains the name of the architec-
+       ture  for  which the JIT compiler is configured, for example "x86 32bit
+       (little endian + unaligned)". If JIT  support  is  not  available,  the
+       result is NULL.
+
+         PCRE_CONFIG_NEWLINE
+
+       The  output  is  an integer whose value specifies the default character
+       sequence that is recognized as meaning "newline". The values  that  are
+       supported in ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338
+       for CRLF, -2 for ANYCRLF, and -1 for ANY. In EBCDIC  environments,  CR,
+       ANYCRLF,  and  ANY  yield the same values. However, the value for LF is
+       normally 21, though some EBCDIC environments use 37. The  corresponding
+       values  for  CRLF are 3349 and 3365. The default should normally corre-
+       spond to the standard sequence for your operating system.
+
+         PCRE_CONFIG_BSR
+
+       The output is an integer whose value indicates what character sequences
+       the  \R  escape sequence matches by default. A value of 0 means that \R
+       matches any Unicode line ending sequence; a value of 1  means  that  \R
+       matches only CR, LF, or CRLF. The default can be overridden when a pat-
+       tern is compiled or matched.
+
+         PCRE_CONFIG_LINK_SIZE
+
+       The output is an integer that contains the number  of  bytes  used  for
+       internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
+       library, the value can be 2, 3, or 4. For the 16-bit library, the value
+       is  either  2  or  4  and  is  still  a number of bytes. For the 32-bit
+       library, the value is either 2 or 4 and is still a number of bytes. The
+       default value of 2 is sufficient for all but the most massive patterns,
+       since it allows the compiled pattern to be up to 64K  in  size.  Larger
+       values  allow larger regular expressions to be compiled, at the expense
+       of slower matching.
+
+         PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
+
+       The output is an integer that contains the threshold  above  which  the
+       POSIX  interface  uses malloc() for output vectors. Further details are
+       given in the pcreposix documentation.
+
+         PCRE_CONFIG_PARENS_LIMIT
+
+       The output is a long integer that gives the maximum depth of nesting of
+       parentheses  (of  any  kind) in a pattern. This limit is imposed to cap
+       the amount of system stack used when a pattern is compiled. It is spec-
+       ified  when PCRE is built; the default is 250. This limit does not take
+       into account the stack that may already be used by the calling applica-
+       tion.  For  finer  control  over compilation stack usage, you can set a
+       pointer to an external checking function in pcre_stack_guard.
+
+         PCRE_CONFIG_MATCH_LIMIT
+
+       The output is a long integer that gives the default limit for the  num-
+       ber  of  internal  matching  function calls in a pcre_exec() execution.
+       Further details are given with pcre_exec() below.
+
+         PCRE_CONFIG_MATCH_LIMIT_RECURSION
+
+       The output is a long integer that gives the default limit for the depth
+       of   recursion  when  calling  the  internal  matching  function  in  a
+       pcre_exec() execution.  Further  details  are  given  with  pcre_exec()
+       below.
+
+         PCRE_CONFIG_STACKRECURSE
+
+       The  output is an integer that is set to one if internal recursion when
+       running pcre_exec() is implemented by recursive function calls that use
+       the  stack  to remember their state. This is the usual way that PCRE is
+       compiled. The output is zero if PCRE was compiled to use blocks of data
+       on  the  heap  instead  of  recursive  function  calls.  In  this case,
+       pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory
+       blocks on the heap, thus avoiding the use of the stack.
+
+
+COMPILING A PATTERN
+
+       pcre *pcre_compile(const char *pattern, int options,
+            const char **errptr, int *erroffset,
+            const unsigned char *tableptr);
+
+       pcre *pcre_compile2(const char *pattern, int options,
+            int *errorcodeptr,
+            const char **errptr, int *erroffset,
+            const unsigned char *tableptr);
+
+       Either of the functions pcre_compile() or pcre_compile2() can be called
+       to compile a pattern into an internal form. The only difference between
+       the  two interfaces is that pcre_compile2() has an additional argument,
+       errorcodeptr, via which a numerical error  code  can  be  returned.  To
+       avoid  too  much repetition, we refer just to pcre_compile() below, but
+       the information applies equally to pcre_compile2().
+
+       The pattern is a C string terminated by a binary zero, and is passed in
+       the  pattern  argument.  A  pointer to a single block of memory that is
+       obtained via pcre_malloc is returned. This contains the  compiled  code
+       and related data. The pcre type is defined for the returned block; this
+       is a typedef for a structure whose contents are not externally defined.
+       It is up to the caller to free the memory (via pcre_free) when it is no
+       longer required.
+
+       Although the compiled code of a PCRE regex is relocatable, that is,  it
+       does not depend on memory location, the complete pcre data block is not
+       fully relocatable, because it may contain a copy of the tableptr  argu-
+       ment, which is an address (see below).
+
+       The options argument contains various bit settings that affect the com-
+       pilation. It should be zero if no options are required.  The  available
+       options  are  described  below. Some of them (in particular, those that
+       are compatible with Perl, but some others as well) can also be set  and
+       unset  from  within  the  pattern  (see the detailed description in the
+       pcrepattern documentation). For those options that can be different  in
+       different  parts  of  the pattern, the contents of the options argument
+       specifies their settings at the start of compilation and execution. The
+       PCRE_ANCHORED,  PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK, and
+       PCRE_NO_START_OPTIMIZE options can be set at the time  of  matching  as
+       well as at compile time.
+
+       If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
+       if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and
+       sets the variable pointed to by errptr to point to a textual error mes-
+       sage. This is a static string that is part of the library. You must not
+       try  to  free it. Normally, the offset from the start of the pattern to
+       the data unit that was being processed when the error was discovered is
+       placed  in the variable pointed to by erroffset, which must not be NULL
+       (if it is, an immediate error is given). However, for an invalid  UTF-8
+       or  UTF-16  string,  the  offset  is that of the first data unit of the
+       failing character.
+
+       Some errors are not detected until the whole pattern has been  scanned;
+       in  these  cases,  the offset passed back is the length of the pattern.
+       Note that the offset is in data units, not characters, even  in  a  UTF
+       mode. It may sometimes point into the middle of a UTF-8 or UTF-16 char-
+       acter.
+
+       If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
+       codeptr  argument is not NULL, a non-zero error code number is returned
+       via this argument in the event of an error. This is in addition to  the
+       textual error message. Error codes and messages are listed below.
+
+       If  the  final  argument, tableptr, is NULL, PCRE uses a default set of
+       character tables that are  built  when  PCRE  is  compiled,  using  the
+       default  C  locale.  Otherwise, tableptr must be an address that is the
+       result of a call to pcre_maketables(). This value is  stored  with  the
+       compiled  pattern,  and  used  again by pcre_exec() and pcre_dfa_exec()
+       when the pattern is matched. For more discussion, see  the  section  on
+       locale support below.
+
+       This  code  fragment  shows a typical straightforward call to pcre_com-
+       pile():
+
+         pcre *re;
+         const char *error;
+         int erroffset;
+         re = pcre_compile(
+           "^A.*Z",          /* the pattern */
+           0,                /* default options */
+           &error,           /* for error message */
+           &erroffset,       /* for error offset */
+           NULL);            /* use default character tables */
+
+       The following names for option bits are defined in  the  pcre.h  header
+       file:
+
+         PCRE_ANCHORED
+
+       If this bit is set, the pattern is forced to be "anchored", that is, it
+       is constrained to match only at the first matching point in the  string
+       that  is being searched (the "subject string"). This effect can also be
+       achieved by appropriate constructs in the pattern itself, which is  the
+       only way to do it in Perl.
+
+         PCRE_AUTO_CALLOUT
+
+       If this bit is set, pcre_compile() automatically inserts callout items,
+       all with number 255, before each pattern item. For  discussion  of  the
+       callout facility, see the pcrecallout documentation.
+
+         PCRE_BSR_ANYCRLF
+         PCRE_BSR_UNICODE
+
+       These options (which are mutually exclusive) control what the \R escape
+       sequence matches. The choice is either to match only CR, LF,  or  CRLF,
+       or to match any Unicode newline sequence. The default is specified when
+       PCRE is built. It can be overridden from within the pattern, or by set-
+       ting an option when a compiled pattern is matched.
+
+         PCRE_CASELESS
+
+       If  this  bit is set, letters in the pattern match both upper and lower
+       case letters. It is equivalent to Perl's  /i  option,  and  it  can  be
+       changed  within a pattern by a (?i) option setting. In UTF-8 mode, PCRE
+       always understands the concept of case for characters whose values  are
+       less  than 128, so caseless matching is always possible. For characters
+       with higher values, the concept of case is supported if  PCRE  is  com-
+       piled  with Unicode property support, but not otherwise. If you want to
+       use caseless matching for characters 128 and  above,  you  must  ensure
+       that  PCRE  is  compiled  with Unicode property support as well as with
+       UTF-8 support.
+
+         PCRE_DOLLAR_ENDONLY
+
+       If this bit is set, a dollar metacharacter in the pattern matches  only
+       at  the  end  of the subject string. Without this option, a dollar also
+       matches immediately before a newline at the end of the string (but  not
+       before  any  other newlines). The PCRE_DOLLAR_ENDONLY option is ignored
+       if PCRE_MULTILINE is set.  There is no equivalent  to  this  option  in
+       Perl, and no way to set it within a pattern.
+
+         PCRE_DOTALL
+
+       If  this bit is set, a dot metacharacter in the pattern matches a char-
+       acter of any value, including one that indicates a newline. However, it
+       only  ever  matches  one character, even if newlines are coded as CRLF.
+       Without this option, a dot does not match when the current position  is
+       at a newline. This option is equivalent to Perl's /s option, and it can
+       be changed within a pattern by a (?s) option setting. A negative  class
+       such as [^a] always matches newline characters, independent of the set-
+       ting of this option.
+
+         PCRE_DUPNAMES
+
+       If this bit is set, names used to identify capturing  subpatterns  need
+       not be unique. This can be helpful for certain types of pattern when it
+       is known that only one instance of the named  subpattern  can  ever  be
+       matched.  There  are  more details of named subpatterns below; see also
+       the pcrepattern documentation.
+
+         PCRE_EXTENDED
+
+       If this bit is set, most white space  characters  in  the  pattern  are
+       totally  ignored  except when escaped or inside a character class. How-
+       ever, white space is not allowed within  sequences  such  as  (?>  that
+       introduce  various  parenthesized  subpatterns,  nor within a numerical
+       quantifier such as {1,3}.  However, ignorable white space is  permitted
+       between an item and a following quantifier and between a quantifier and
+       a following + that indicates possessiveness.
+
+       White space did not used to include the VT character (code 11), because
+       Perl did not treat this character as white space. However, Perl changed
+       at release 5.18, so PCRE followed  at  release  8.34,  and  VT  is  now
+       treated as white space.
+
+       PCRE_EXTENDED  also  causes characters between an unescaped # outside a
+       character class  and  the  next  newline,  inclusive,  to  be  ignored.
+       PCRE_EXTENDED  is equivalent to Perl's /x option, and it can be changed
+       within a pattern by a (?x) option setting.
+
+       Which characters are interpreted  as  newlines  is  controlled  by  the
+       options  passed to pcre_compile() or by a special sequence at the start
+       of the pattern, as described in the section entitled  "Newline  conven-
+       tions" in the pcrepattern documentation. Note that the end of this type
+       of comment is  a  literal  newline  sequence  in  the  pattern;  escape
+       sequences that happen to represent a newline do not count.
+
+       This  option  makes  it possible to include comments inside complicated
+       patterns.  Note, however, that this applies only  to  data  characters.
+       White  space  characters  may  never  appear  within  special character
+       sequences in a pattern, for example within the sequence (?( that intro-
+       duces a conditional subpattern.
+
+         PCRE_EXTRA
+
+       This  option  was invented in order to turn on additional functionality
+       of PCRE that is incompatible with Perl, but it  is  currently  of  very
+       little  use. When set, any backslash in a pattern that is followed by a
+       letter that has no special meaning  causes  an  error,  thus  reserving
+       these  combinations  for  future  expansion.  By default, as in Perl, a
+       backslash followed by a letter with no special meaning is treated as  a
+       literal. (Perl can, however, be persuaded to give an error for this, by
+       running it with the -w option.) There are at present no other  features
+       controlled  by this option. It can also be set by a (?X) option setting
+       within a pattern.
+
+         PCRE_FIRSTLINE
+
+       If this option is set, an  unanchored  pattern  is  required  to  match
+       before  or  at  the  first  newline  in  the subject string, though the
+       matched text may continue over the newline.
+
+         PCRE_JAVASCRIPT_COMPAT
+
+       If this option is set, PCRE's behaviour is changed in some ways so that
+       it  is  compatible with JavaScript rather than Perl. The changes are as
+       follows:
+
+       (1) A lone closing square bracket in a pattern  causes  a  compile-time
+       error,  because this is illegal in JavaScript (by default it is treated
+       as a data character). Thus, the pattern AB]CD becomes illegal when this
+       option is set.
+
+       (2)  At run time, a back reference to an unset subpattern group matches
+       an empty string (by default this causes the current  matching  alterna-
+       tive  to  fail). A pattern such as (\1)(a) succeeds when this option is
+       set (assuming it can find an "a" in the subject), whereas it  fails  by
+       default, for Perl compatibility.
+
+       (3) \U matches an upper case "U" character; by default \U causes a com-
+       pile time error (Perl uses \U to upper case subsequent characters).
+
+       (4) \u matches a lower case "u" character unless it is followed by four
+       hexadecimal  digits,  in  which case the hexadecimal number defines the
+       code point to match. By default, \u causes a compile time  error  (Perl
+       uses it to upper case the following character).
+
+       (5)  \x matches a lower case "x" character unless it is followed by two
+       hexadecimal digits, in which case the hexadecimal  number  defines  the
+       code  point  to  match. By default, as in Perl, a hexadecimal number is
+       always expected after \x, but it may have zero, one, or two digits (so,
+       for example, \xz matches a binary zero character followed by z).
+
+         PCRE_MULTILINE
+
+       By  default,  for  the purposes of matching "start of line" and "end of
+       line", PCRE treats the subject string as consisting of a single line of
+       characters,  even if it actually contains newlines. The "start of line"
+       metacharacter (^) matches only at the start of the string, and the "end
+       of  line"  metacharacter  ($) matches only at the end of the string, or
+       before a terminating newline (except when PCRE_DOLLAR_ENDONLY is  set).
+       Note,  however,  that  unless  PCRE_DOTALL  is set, the "any character"
+       metacharacter (.) does not match at a newline. This behaviour  (for  ^,
+       $, and dot) is the same as Perl.
+
+       When  PCRE_MULTILINE  it  is set, the "start of line" and "end of line"
+       constructs match immediately following or immediately  before  internal
+       newlines  in  the  subject string, respectively, as well as at the very
+       start and end. This is equivalent to Perl's /m option, and  it  can  be
+       changed within a pattern by a (?m) option setting. If there are no new-
+       lines in a subject string, or no occurrences of ^ or $  in  a  pattern,
+       setting PCRE_MULTILINE has no effect.
+
+         PCRE_NEVER_UTF
+
+       This option locks out interpretation of the pattern as UTF-8 (or UTF-16
+       or UTF-32 in the 16-bit and 32-bit libraries). In particular,  it  pre-
+       vents  the  creator of the pattern from switching to UTF interpretation
+       by starting the pattern with (*UTF). This may be useful in applications
+       that  process  patterns  from  external  sources.  The  combination  of
+       PCRE_UTF8 and PCRE_NEVER_UTF also causes an error.
+
+         PCRE_NEWLINE_CR
+         PCRE_NEWLINE_LF
+         PCRE_NEWLINE_CRLF
+         PCRE_NEWLINE_ANYCRLF
+         PCRE_NEWLINE_ANY
+
+       These options override the default newline definition that  was  chosen
+       when  PCRE  was built. Setting the first or the second specifies that a
+       newline is indicated by a single character (CR  or  LF,  respectively).
+       Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the
+       two-character CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF  specifies
+       that any of the three preceding sequences should be recognized. Setting
+       PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should  be
+       recognized.
+
+       In  an ASCII/Unicode environment, the Unicode newline sequences are the
+       three just mentioned, plus the  single  characters  VT  (vertical  tab,
+       U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
+       arator, U+2028), and PS (paragraph separator, U+2029).  For  the  8-bit
+       library, the last two are recognized only in UTF-8 mode.
+
+       When  PCRE is compiled to run in an EBCDIC (mainframe) environment, the
+       code for CR is 0x0d, the same as ASCII. However, the character code for
+       LF  is  normally 0x15, though in some EBCDIC environments 0x25 is used.
+       Whichever of these is not LF is made to  correspond  to  Unicode's  NEL
+       character.  EBCDIC  codes  are all less than 256. For more details, see
+       the pcrebuild documentation.
+
+       The newline setting in the  options  word  uses  three  bits  that  are
+       treated as a number, giving eight possibilities. Currently only six are
+       used (default plus the five values above). This means that if  you  set
+       more  than one newline option, the combination may or may not be sensi-
+       ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to
+       PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and
+       cause an error.
+
+       The only time that a line break in a pattern  is  specially  recognized
+       when  compiling is when PCRE_EXTENDED is set. CR and LF are white space
+       characters, and so are ignored in this mode. Also, an unescaped #  out-
+       side  a  character class indicates a comment that lasts until after the
+       next line break sequence. In other circumstances, line break  sequences
+       in patterns are treated as literal data.
+
+       The newline option that is set at compile time becomes the default that
+       is used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.
+
+         PCRE_NO_AUTO_CAPTURE
+
+       If this option is set, it disables the use of numbered capturing paren-
+       theses  in the pattern. Any opening parenthesis that is not followed by
+       ? behaves as if it were followed by ?: but named parentheses can  still
+       be  used  for  capturing  (and  they acquire numbers in the usual way).
+       There is no equivalent of this option in Perl.
+
+         PCRE_NO_AUTO_POSSESS
+
+       If this option is set, it disables "auto-possessification". This is  an
+       optimization  that,  for example, turns a+b into a++b in order to avoid
+       backtracks into a+ that can never be successful. However,  if  callouts
+       are  in  use,  auto-possessification  means that some of them are never
+       taken. You can set this option if you want the matching functions to do
+       a  full  unoptimized  search and run all the callouts, but it is mainly
+       provided for testing purposes.
+
+         PCRE_NO_START_OPTIMIZE
+
+       This is an option that acts at matching time; that is, it is really  an
+       option  for  pcre_exec()  or  pcre_dfa_exec().  If it is set at compile
+       time, it is remembered with the compiled pattern and assumed at  match-
+       ing  time.  This is necessary if you want to use JIT execution, because
+       the JIT compiler needs to know whether or not this option is  set.  For
+       details see the discussion of PCRE_NO_START_OPTIMIZE below.
+
+         PCRE_UCP
+
+       This  option changes the way PCRE processes \B, \b, \D, \d, \S, \s, \W,
+       \w, and some of the POSIX character classes.  By  default,  only  ASCII
+       characters  are  recognized, but if PCRE_UCP is set, Unicode properties
+       are used instead to classify characters. More details are given in  the
+       section  on generic character types in the pcrepattern page. If you set
+       PCRE_UCP, matching one of the items it affects takes much  longer.  The
+       option  is  available only if PCRE has been compiled with Unicode prop-
+       erty support.
+
+         PCRE_UNGREEDY
+
+       This option inverts the "greediness" of the quantifiers  so  that  they
+       are  not greedy by default, but become greedy if followed by "?". It is
+       not compatible with Perl. It can also be set by a (?U)  option  setting
+       within the pattern.
+
+         PCRE_UTF8
+
+       This  option  causes PCRE to regard both the pattern and the subject as
+       strings of UTF-8 characters instead of single-byte strings. However, it
+       is  available  only  when PCRE is built to include UTF support. If not,
+       the use of this option provokes an error. Details of  how  this  option
+       changes the behaviour of PCRE are given in the pcreunicode page.
+
+         PCRE_NO_UTF8_CHECK
+
+       When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
+       automatically checked. There is a  discussion  about  the  validity  of
+       UTF-8  strings in the pcreunicode page. If an invalid UTF-8 sequence is
+       found, pcre_compile() returns an error. If you already know  that  your
+       pattern  is valid, and you want to skip this check for performance rea-
+       sons, you can set the PCRE_NO_UTF8_CHECK option.  When it is  set,  the
+       effect of passing an invalid UTF-8 string as a pattern is undefined. It
+       may cause your program to crash or loop. Note that this option can also
+       be  passed to pcre_exec() and pcre_dfa_exec(), to suppress the validity
+       checking of subject strings only. If the same string is  being  matched
+       many  times, the option can be safely set for the second and subsequent
+       matchings to improve performance.
+
+
+COMPILATION ERROR CODES
+
+       The following table lists the error  codes  than  may  be  returned  by
+       pcre_compile2(),  along with the error messages that may be returned by
+       both compiling functions. Note that error  messages  are  always  8-bit
+       ASCII  strings,  even  in 16-bit or 32-bit mode. As PCRE has developed,
+       some error codes have fallen out of use. To avoid confusion, they  have
+       not been re-used.
+
+          0  no error
+          1  \ at end of pattern
+          2  \c at end of pattern
+          3  unrecognized character follows \
+          4  numbers out of order in {} quantifier
+          5  number too big in {} quantifier
+          6  missing terminating ] for character class
+          7  invalid escape sequence in character class
+          8  range out of order in character class
+          9  nothing to repeat
+         10  [this code is not in use]
+         11  internal error: unexpected repeat
+         12  unrecognized character after (? or (?-
+         13  POSIX named classes are supported only within a class
+         14  missing )
+         15  reference to non-existent subpattern
+         16  erroffset passed as NULL
+         17  unknown option bit(s) set
+         18  missing ) after comment
+         19  [this code is not in use]
+         20  regular expression is too large
+         21  failed to get memory
+         22  unmatched parentheses
+         23  internal error: code overflow
+         24  unrecognized character after (?<
+         25  lookbehind assertion is not fixed length
+         26  malformed number or name after (?(
+         27  conditional group contains more than two branches
+         28  assertion expected after (?(
+         29  (?R or (?[+-]digits must be followed by )
+         30  unknown POSIX class name
+         31  POSIX collating elements are not supported
+         32  this version of PCRE is compiled without UTF support
+         33  [this code is not in use]
+         34  character value in \x{} or \o{} is too large
+         35  invalid condition (?(0)
+         36  \C not allowed in lookbehind assertion
+         37  PCRE does not support \L, \l, \N{name}, \U, or \u
+         38  number after (?C is > 255
+         39  closing ) for (?C expected
+         40  recursive call could loop indefinitely
+         41  unrecognized character after (?P
+         42  syntax error in subpattern name (missing terminator)
+         43  two named subpatterns have the same name
+         44  invalid UTF-8 string (specifically UTF-8)
+         45  support for \P, \p, and \X has not been compiled
+         46  malformed \P or \p sequence
+         47  unknown property name after \P or \p
+         48  subpattern name is too long (maximum 32 characters)
+         49  too many named subpatterns (maximum 10000)
+         50  [this code is not in use]
+         51  octal value is greater than \377 in 8-bit non-UTF-8 mode
+         52  internal error: overran compiling workspace
+         53  internal error: previously-checked referenced subpattern
+               not found
+         54  DEFINE group contains more than one branch
+         55  repeating a DEFINE group is not allowed
+         56  inconsistent NEWLINE options
+         57  \g is not followed by a braced, angle-bracketed, or quoted
+               name/number or by a plain number
+         58  a numbered reference must not be zero
+         59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
+         60  (*VERB) not recognized or malformed
+         61  number is too big
+         62  subpattern name expected
+         63  digit expected after (?+
+         64  ] is an invalid data character in JavaScript compatibility mode
+         65  different names for subpatterns of the same number are
+               not allowed
+         66  (*MARK) must have an argument
+         67  this version of PCRE is not compiled with Unicode property
+               support
+         68  \c must be followed by an ASCII character
+         69  \k is not followed by a braced, angle-bracketed, or quoted name
+         70  internal error: unknown opcode in find_fixedlength()
+         71  \N is not supported in a class
+         72  too many forward references
+         73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
+         74  invalid UTF-16 string (specifically UTF-16)
+         75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
+         76  character value in \u.... sequence is too large
+         77  invalid UTF-32 string (specifically UTF-32)
+         78  setting UTF is disabled by the application
+         79  non-hex character in \x{} (closing brace missing?)
+         80  non-octal character in \o{} (closing brace missing?)
+         81  missing opening brace after \o
+         82  parentheses are too deeply nested
+         83  invalid range in character class
+         84  group name must start with a non-digit
+         85  parentheses are too deeply nested (stack check)
+
+       The  numbers  32  and 10000 in errors 48 and 49 are defaults; different
+       values may be used if the limits were changed when PCRE was built.
+
+
+STUDYING A PATTERN
+
+       pcre_extra *pcre_study(const pcre *code, int options,
+            const char **errptr);
+
+       If a compiled pattern is going to be used several times,  it  is  worth
+       spending more time analyzing it in order to speed up the time taken for
+       matching. The function pcre_study() takes a pointer to a compiled  pat-
+       tern as its first argument. If studying the pattern produces additional
+       information that will help speed up matching,  pcre_study()  returns  a
+       pointer  to a pcre_extra block, in which the study_data field points to
+       the results of the study.
+
+       The  returned  value  from  pcre_study()  can  be  passed  directly  to
+       pcre_exec()  or  pcre_dfa_exec(). However, a pcre_extra block also con-
+       tains other fields that can be set by the caller before  the  block  is
+       passed; these are described below in the section on matching a pattern.
+
+       If  studying  the  pattern  does  not  produce  any useful information,
+       pcre_study() returns NULL by default.  In  that  circumstance,  if  the
+       calling program wants to pass any of the other fields to pcre_exec() or
+       pcre_dfa_exec(), it must set up its own pcre_extra block.  However,  if
+       pcre_study()  is  called  with  the  PCRE_STUDY_EXTRA_NEEDED option, it
+       returns a pcre_extra block even if studying did not find any additional
+       information.  It  may still return NULL, however, if an error occurs in
+       pcre_study().
+
+       The second argument of pcre_study() contains  option  bits.  There  are
+       three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
+
+         PCRE_STUDY_JIT_COMPILE
+         PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+         PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+
+       If  any  of  these are set, and the just-in-time compiler is available,
+       the pattern is further compiled into machine code  that  executes  much
+       faster  than  the  pcre_exec()  interpretive  matching function. If the
+       just-in-time compiler is not available, these options are ignored.  All
+       undefined bits in the options argument must be zero.
+
+       JIT  compilation  is  a heavyweight optimization. It can take some time
+       for patterns to be analyzed, and for one-off matches  and  simple  pat-
+       terns  the benefit of faster execution might be offset by a much slower
+       study time.  Not all patterns can be optimized by the JIT compiler. For
+       those  that cannot be handled, matching automatically falls back to the
+       pcre_exec() interpreter. For more details, see the  pcrejit  documenta-
+       tion.
+
+       The  third argument for pcre_study() is a pointer for an error message.
+       If studying succeeds (even if no data is  returned),  the  variable  it
+       points  to  is  set  to NULL. Otherwise it is set to point to a textual
+       error message. This is a static string that is part of the library. You
+       must  not  try  to  free it. You should test the error pointer for NULL
+       after calling pcre_study(), to be sure that it has run successfully.
+
+       When you are finished with a pattern, you can free the memory used  for
+       the study data by calling pcre_free_study(). This function was added to
+       the API for release 8.20. For earlier versions,  the  memory  could  be
+       freed  with  pcre_free(), just like the pattern itself. This will still
+       work in cases where JIT optimization is not used, but it  is  advisable
+       to change to the new function when convenient.
+
+       This  is  a typical way in which pcre_study() is used (except that in a
+       real application there should be tests for errors):
+
+         int rc;
+         pcre *re;
+         pcre_extra *sd;
+         re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
+         sd = pcre_study(
+           re,             /* result of pcre_compile() */
+           0,              /* no options */
+           &error);        /* set to NULL or points to a message */
+         rc = pcre_exec(   /* see below for details of pcre_exec() options */
+           re, sd, "subject", 7, 0, 0, ovector, 30);
+         ...
+         pcre_free_study(sd);
+         pcre_free(re);
+
+       Studying a pattern does two things: first, a lower bound for the length
+       of subject string that is needed to match the pattern is computed. This
+       does not mean that there are any strings of that length that match, but
+       it  does  guarantee that no shorter strings match. The value is used to
+       avoid wasting time by trying to match strings that are shorter than the
+       lower  bound.  You  can find out the value in a calling program via the
+       pcre_fullinfo() function.
+
+       Studying a pattern is also useful for non-anchored patterns that do not
+       have  a  single fixed starting character. A bitmap of possible starting
+       bytes is created. This speeds up finding a position in the  subject  at
+       which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
+       values less than 256.  In 32-bit mode, the bitmap is  used  for  32-bit
+       values less than 256.)
+
+       These  two optimizations apply to both pcre_exec() and pcre_dfa_exec(),
+       and the information is also used by the JIT  compiler.   The  optimiza-
+       tions  can  be  disabled  by setting the PCRE_NO_START_OPTIMIZE option.
+       You might want to do this if your pattern contains callouts or  (*MARK)
+       and  you  want  to make use of these facilities in cases where matching
+       fails.
+
+       PCRE_NO_START_OPTIMIZE can be specified at either compile time or  exe-
+       cution   time.   However,   if   PCRE_NO_START_OPTIMIZE  is  passed  to
+       pcre_exec(), (that is, after any JIT compilation has happened) JIT exe-
+       cution  is disabled. For JIT execution to work with PCRE_NO_START_OPTI-
+       MIZE, the option must be set at compile time.
+
+       There is a longer discussion of PCRE_NO_START_OPTIMIZE below.
+
+
+LOCALE SUPPORT
+
+       PCRE handles caseless matching, and determines whether  characters  are
+       letters,  digits, or whatever, by reference to a set of tables, indexed
+       by character code point. When running in UTF-8 mode, or in the  16-  or
+       32-bit libraries, this applies only to characters with code points less
+       than 256. By default, higher-valued code  points  never  match  escapes
+       such  as \w or \d. However, if PCRE is built with Unicode property sup-
+       port, all characters can be tested with \p and \P,  or,  alternatively,
+       the  PCRE_UCP option can be set when a pattern is compiled; this causes
+       \w and friends to use Unicode property support instead of the  built-in
+       tables.
+
+       The  use  of  locales  with Unicode is discouraged. If you are handling
+       characters with code points greater than 128,  you  should  either  use
+       Unicode support, or use locales, but not try to mix the two.
+
+       PCRE  contains  an  internal set of tables that are used when the final
+       argument of pcre_compile() is  NULL.  These  are  sufficient  for  many
+       applications.  Normally, the internal tables recognize only ASCII char-
+       acters. However, when PCRE is built, it is possible to cause the inter-
+       nal tables to be rebuilt in the default "C" locale of the local system,
+       which may cause them to be different.
+
+       The internal tables can always be overridden by tables supplied by  the
+       application that calls PCRE. These may be created in a different locale
+       from the default. As more and more applications change  to  using  Uni-
+       code, the need for this locale support is expected to die away.
+
+       External  tables  are  built by calling the pcre_maketables() function,
+       which has no arguments, in the relevant locale. The result can then  be
+       passed  to  pcre_compile() as often as necessary. For example, to build
+       and use tables that  are  appropriate  for  the  French  locale  (where
+       accented  characters  with  values greater than 128 are treated as let-
+       ters), the following code could be used:
+
+         setlocale(LC_CTYPE, "fr_FR");
+         tables = pcre_maketables();
+         re = pcre_compile(..., tables);
+
+       The locale name "fr_FR" is used on Linux and other  Unix-like  systems;
+       if you are using Windows, the name for the French locale is "french".
+
+       When  pcre_maketables()  runs,  the  tables are built in memory that is
+       obtained via pcre_malloc. It is the caller's responsibility  to  ensure
+       that  the memory containing the tables remains available for as long as
+       it is needed.
+
+       The pointer that is passed to pcre_compile() is saved with the compiled
+       pattern,  and the same tables are used via this pointer by pcre_study()
+       and also by pcre_exec() and pcre_dfa_exec(). Thus, for any single  pat-
+       tern, compilation, studying and matching all happen in the same locale,
+       but different patterns can be processed in different locales.
+
+       It is possible to pass a table pointer or NULL (indicating the  use  of
+       the internal tables) to pcre_exec() or pcre_dfa_exec() (see the discus-
+       sion below in the section on matching a pattern). This facility is pro-
+       vided  for  use  with  pre-compiled  patterns  that have been saved and
+       reloaded.  Character tables are not saved with patterns, so if  a  non-
+       standard table was used at compile time, it must be provided again when
+       the reloaded pattern is matched. Attempting to  use  this  facility  to
+       match a pattern in a different locale from the one in which it was com-
+       piled is likely to lead to anomalous (usually incorrect) results.
+
+
+INFORMATION ABOUT A PATTERN
+
+       int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
+            int what, void *where);
+
+       The pcre_fullinfo() function returns information about a compiled  pat-
+       tern.  It replaces the pcre_info() function, which was removed from the
+       library at version 8.30, after more than 10 years of obsolescence.
+
+       The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
+       pattern.  The second argument is the result of pcre_study(), or NULL if
+       the pattern was not studied. The third argument specifies  which  piece
+       of  information  is required, and the fourth argument is a pointer to a
+       variable to receive the data. The yield of the  function  is  zero  for
+       success, or one of the following negative numbers:
+
+         PCRE_ERROR_NULL           the argument code was NULL
+                                   the argument where was NULL
+         PCRE_ERROR_BADMAGIC       the "magic number" was not found
+         PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
+                                   endianness
+         PCRE_ERROR_BADOPTION      the value of what was invalid
+         PCRE_ERROR_UNSET          the requested field is not set
+
+       The  "magic  number" is placed at the start of each compiled pattern as
+       an simple check against passing an arbitrary memory pointer. The  endi-
+       anness error can occur if a compiled pattern is saved and reloaded on a
+       different host. Here is a typical call of  pcre_fullinfo(),  to  obtain
+       the length of the compiled pattern:
+
+         int rc;
+         size_t length;
+         rc = pcre_fullinfo(
+           re,               /* result of pcre_compile() */
+           sd,               /* result of pcre_study(), or NULL */
+           PCRE_INFO_SIZE,   /* what is required */
+           &length);         /* where to put the data */
+
+       The  possible  values for the third argument are defined in pcre.h, and
+       are as follows:
+
+         PCRE_INFO_BACKREFMAX
+
+       Return the number of the highest back reference  in  the  pattern.  The
+       fourth  argument  should  point to an int variable. Zero is returned if
+       there are no back references.
+
+         PCRE_INFO_CAPTURECOUNT
+
+       Return the number of capturing subpatterns in the pattern.  The  fourth
+       argument should point to an int variable.
+
+         PCRE_INFO_DEFAULT_TABLES
+
+       Return  a pointer to the internal default character tables within PCRE.
+       The fourth argument should point to an unsigned char *  variable.  This
+       information call is provided for internal use by the pcre_study() func-
+       tion. External callers can cause PCRE to use  its  internal  tables  by
+       passing a NULL table pointer.
+
+         PCRE_INFO_FIRSTBYTE (deprecated)
+
+       Return information about the first data unit of any matched string, for
+       a non-anchored pattern. The name of this option  refers  to  the  8-bit
+       library,  where  data units are bytes. The fourth argument should point
+       to an int variable. Negative values are used for  special  cases.  How-
+       ever,  this  means  that when the 32-bit library is in non-UTF-32 mode,
+       the full 32-bit range of characters cannot be returned. For  this  rea-
+       son,  this  value  is deprecated; use PCRE_INFO_FIRSTCHARACTERFLAGS and
+       PCRE_INFO_FIRSTCHARACTER instead.
+
+       If there is a fixed first value, for example, the  letter  "c"  from  a
+       pattern  such  as (cat|cow|coyote), its value is returned. In the 8-bit
+       library, the value is always less than 256. In the 16-bit  library  the
+       value can be up to 0xffff. In the 32-bit library the value can be up to
+       0x10ffff.
+
+       If there is no fixed first value, and if either
+
+       (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
+       branch starts with "^", or
+
+       (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
+       set (if it were set, the pattern would be anchored),
+
+       -1 is returned, indicating that the pattern matches only at  the  start
+       of  a  subject string or after any newline within the string. Otherwise
+       -2 is returned. For anchored patterns, -2 is returned.
+
+         PCRE_INFO_FIRSTCHARACTER
+
+       Return the value of the first data  unit  (non-UTF  character)  of  any
+       matched  string  in  the  situation where PCRE_INFO_FIRSTCHARACTERFLAGS
+       returns 1; otherwise return 0. The fourth argument should point  to  an
+       uint_t variable.
+
+       In  the 8-bit library, the value is always less than 256. In the 16-bit
+       library the value can be up to 0xffff. In the 32-bit library in  UTF-32
+       mode  the  value  can  be up to 0x10ffff, and up to 0xffffffff when not
+       using UTF-32 mode.
+
+         PCRE_INFO_FIRSTCHARACTERFLAGS
+
+       Return information about the first data unit of any matched string, for
+       a  non-anchored  pattern.  The  fourth  argument should point to an int
+       variable.
+
+       If there is a fixed first value, for example, the  letter  "c"  from  a
+       pattern  such  as  (cat|cow|coyote),  1  is returned, and the character
+       value can be retrieved using PCRE_INFO_FIRSTCHARACTER. If there  is  no
+       fixed first value, and if either
+
+       (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
+       branch starts with "^", or
+
+       (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
+       set (if it were set, the pattern would be anchored),
+
+       2 is returned, indicating that the pattern matches only at the start of
+       a subject string or after any newline within the string. Otherwise 0 is
+       returned. For anchored patterns, 0 is returned.
+
+         PCRE_INFO_FIRSTTABLE
+
+       If  the pattern was studied, and this resulted in the construction of a
+       256-bit table indicating a fixed set of values for the first data  unit
+       in  any  matching string, a pointer to the table is returned. Otherwise
+       NULL is returned. The fourth argument should point to an unsigned  char
+       * variable.
+
+         PCRE_INFO_HASCRORLF
+
+       Return  1  if  the  pattern  contains any explicit matches for CR or LF
+       characters, otherwise 0. The fourth argument should  point  to  an  int
+       variable.  An explicit match is either a literal CR or LF character, or
+       \r or \n.
+
+         PCRE_INFO_JCHANGED
+
+       Return 1 if the (?J) or (?-J) option setting is used  in  the  pattern,
+       otherwise  0. The fourth argument should point to an int variable. (?J)
+       and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
+
+         PCRE_INFO_JIT
+
+       Return 1 if the pattern was studied with one of the  JIT  options,  and
+       just-in-time compiling was successful. The fourth argument should point
+       to an int variable. A return value of 0 means that JIT support  is  not
+       available  in this version of PCRE, or that the pattern was not studied
+       with a JIT option, or that the JIT compiler could not handle this  par-
+       ticular  pattern. See the pcrejit documentation for details of what can
+       and cannot be handled.
+
+         PCRE_INFO_JITSIZE
+
+       If the pattern was successfully studied with a JIT option,  return  the
+       size  of the JIT compiled code, otherwise return zero. The fourth argu-
+       ment should point to a size_t variable.
+
+         PCRE_INFO_LASTLITERAL
+
+       Return the value of the rightmost literal data unit that must exist  in
+       any  matched  string, other than at its start, if such a value has been
+       recorded. The fourth argument should point to an int variable. If there
+       is no such value, -1 is returned. For anchored patterns, a last literal
+       value is recorded only if it follows something of variable length.  For
+       example, for the pattern /^a\d+z\d+/ the returned value is "z", but for
+       /^a\dz\d/ the returned value is -1.
+
+       Since for the 32-bit library using the non-UTF-32 mode,  this  function
+       is  unable to return the full 32-bit range of characters, this value is
+       deprecated;     instead     the     PCRE_INFO_REQUIREDCHARFLAGS     and
+       PCRE_INFO_REQUIREDCHAR values should be used.
+
+         PCRE_INFO_MATCH_EMPTY
+
+       Return  1  if  the  pattern can match an empty string, otherwise 0. The
+       fourth argument should point to an int variable.
+
+         PCRE_INFO_MATCHLIMIT
+
+       If the pattern set a match limit by  including  an  item  of  the  form
+       (*LIMIT_MATCH=nnnn)  at  the  start,  the value is returned. The fourth
+       argument should point to an unsigned 32-bit integer. If no  such  value
+       has   been   set,   the  call  to  pcre_fullinfo()  returns  the  error
+       PCRE_ERROR_UNSET.
+
+         PCRE_INFO_MAXLOOKBEHIND
+
+       Return the number of characters (NB not  data  units)  in  the  longest
+       lookbehind  assertion  in  the pattern. This information is useful when
+       doing multi-segment matching using  the  partial  matching  facilities.
+       Note that the simple assertions \b and \B require a one-character look-
+       behind. \A also registers a one-character lookbehind,  though  it  does
+       not  actually inspect the previous character. This is to ensure that at
+       least one character from the old segment is retained when a new segment
+       is processed. Otherwise, if there are no lookbehinds in the pattern, \A
+       might match incorrectly at the start of a new segment.
+
+         PCRE_INFO_MINLENGTH
+
+       If the pattern was studied and a minimum length  for  matching  subject
+       strings  was  computed,  its  value is returned. Otherwise the returned
+       value is -1. The value is a number of characters, which in UTF mode may
+       be  different from the number of data units. The fourth argument should
+       point to an int variable. A non-negative value is a lower bound to  the
+       length  of  any  matching  string. There may not be any strings of that
+       length that do actually match, but every string that does match  is  at
+       least that long.
+
+         PCRE_INFO_NAMECOUNT
+         PCRE_INFO_NAMEENTRYSIZE
+         PCRE_INFO_NAMETABLE
+
+       PCRE  supports the use of named as well as numbered capturing parenthe-
+       ses. The names are just an additional way of identifying the  parenthe-
+       ses, which still acquire numbers. Several convenience functions such as
+       pcre_get_named_substring() are provided for  extracting  captured  sub-
+       strings  by  name. It is also possible to extract the data directly, by
+       first converting the name to a number in order to  access  the  correct
+       pointers in the output vector (described with pcre_exec() below). To do
+       the conversion, you need  to  use  the  name-to-number  map,  which  is
+       described by these three values.
+
+       The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
+       gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
+       of  each  entry;  both  of  these  return  an int value. The entry size
+       depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns
+       a pointer to the first entry of the table. This is a pointer to char in
+       the 8-bit library, where the first two bytes of each entry are the num-
+       ber  of  the capturing parenthesis, most significant byte first. In the
+       16-bit library, the pointer points to 16-bit data units, the  first  of
+       which  contains  the  parenthesis  number.  In  the 32-bit library, the
+       pointer points to 32-bit data units, the first of  which  contains  the
+       parenthesis  number.  The  rest of the entry is the corresponding name,
+       zero terminated.
+
+       The names are in alphabetical order. If (?| is used to create  multiple
+       groups  with  the same number, as described in the section on duplicate
+       subpattern numbers in the pcrepattern page, the groups may be given the
+       same  name,  but  there is only one entry in the table. Different names
+       for groups of the same number are not permitted.  Duplicate  names  for
+       subpatterns with different numbers are permitted, but only if PCRE_DUP-
+       NAMES is set. They appear in the table in the order in which they  were
+       found  in  the  pattern.  In  the  absence  of (?| this is the order of
+       increasing number; when (?| is used this is not  necessarily  the  case
+       because later subpatterns may have lower numbers.
+
+       As  a  simple  example of the name/number table, consider the following
+       pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
+       set, so white space - including newlines - is ignored):
+
+         (? (?(\d\d)?\d\d) -
+         (?\d\d) - (?\d\d) )
+
+       There  are  four  named subpatterns, so the table has four entries, and
+       each entry in the table is eight bytes long. The table is  as  follows,
+       with non-printing bytes shows in hexadecimal, and undefined bytes shown
+       as ??:
+
+         00 01 d  a  t  e  00 ??
+         00 05 d  a  y  00 ?? ??
+         00 04 m  o  n  t  h  00
+         00 02 y  e  a  r  00 ??
+
+       When writing code to extract data  from  named  subpatterns  using  the
+       name-to-number  map,  remember that the length of the entries is likely
+       to be different for each compiled pattern.
+
+         PCRE_INFO_OKPARTIAL
+
+       Return 1  if  the  pattern  can  be  used  for  partial  matching  with
+       pcre_exec(),  otherwise  0.  The fourth argument should point to an int
+       variable. From  release  8.00,  this  always  returns  1,  because  the
+       restrictions  that  previously  applied  to  partial matching have been
+       lifted. The pcrepartial documentation gives details of  partial  match-
+       ing.
+
+         PCRE_INFO_OPTIONS
+
+       Return  a  copy of the options with which the pattern was compiled. The
+       fourth argument should point to an unsigned long  int  variable.  These
+       option bits are those specified in the call to pcre_compile(), modified
+       by any top-level option settings at the start of the pattern itself. In
+       other  words,  they are the options that will be in force when matching
+       starts. For example, if the pattern /(?im)abc(?-i)d/ is  compiled  with
+       the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
+       and PCRE_EXTENDED.
+
+       A pattern is automatically anchored by PCRE if  all  of  its  top-level
+       alternatives begin with one of the following:
+
+         ^     unless PCRE_MULTILINE is set
+         \A    always
+         \G    always
+         .*    if PCRE_DOTALL is set and there are no back
+                 references to the subpattern in which .* appears
+
+       For such patterns, the PCRE_ANCHORED bit is set in the options returned
+       by pcre_fullinfo().
+
+         PCRE_INFO_RECURSIONLIMIT
+
+       If the pattern set a recursion limit by including an item of  the  form
+       (*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth
+       argument should point to an unsigned 32-bit integer. If no  such  value
+       has   been   set,   the  call  to  pcre_fullinfo()  returns  the  error
+       PCRE_ERROR_UNSET.
+
+         PCRE_INFO_SIZE
+
+       Return the size of  the  compiled  pattern  in  bytes  (for  all  three
+       libraries). The fourth argument should point to a size_t variable. This
+       value does not include the size of the pcre structure that is  returned
+       by  pcre_compile().  The  value  that  is  passed  as  the  argument to
+       pcre_malloc() when pcre_compile() is getting memory in which  to  place
+       the compiled data is the value returned by this option plus the size of
+       the pcre structure. Studying a compiled pattern, with or  without  JIT,
+       does not alter the value returned by this option.
+
+         PCRE_INFO_STUDYSIZE
+
+       Return  the  size  in bytes (for all three libraries) of the data block
+       pointed to by the study_data field in a pcre_extra block. If pcre_extra
+       is  NULL, or there is no study data, zero is returned. The fourth argu-
+       ment should point to a size_t variable. The study_data field is set  by
+       pcre_study() to record information that will speed up matching (see the
+       section entitled  "Studying  a  pattern"  above).  The  format  of  the
+       study_data  block is private, but its length is made available via this
+       option so that it can be saved and  restored  (see  the  pcreprecompile
+       documentation for details).
+
+         PCRE_INFO_REQUIREDCHARFLAGS
+
+       Returns  1 if there is a rightmost literal data unit that must exist in
+       any matched string, other than at its start. The fourth argument should
+       point  to an int variable. If there is no such value, 0 is returned. If
+       returning  1,  the  character  value  itself  can  be  retrieved  using
+       PCRE_INFO_REQUIREDCHAR.
+
+       For anchored patterns, a last literal value is recorded only if it fol-
+       lows something  of  variable  length.  For  example,  for  the  pattern
+       /^a\d+z\d+/   the   returned   value   1   (with   "z"   returned  from
+       PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.
+
+         PCRE_INFO_REQUIREDCHAR
+
+       Return the value of the rightmost literal data unit that must exist  in
+       any  matched  string, other than at its start, if such a value has been
+       recorded. The fourth argument should point to an uint32_t variable.  If
+       there is no such value, 0 is returned.
+
+
+REFERENCE COUNTS
+
+       int pcre_refcount(pcre *code, int adjust);
+
+       The  pcre_refcount()  function is used to maintain a reference count in
+       the data block that contains a compiled pattern. It is provided for the
+       benefit  of  applications  that  operate  in an object-oriented manner,
+       where different parts of the application may be using the same compiled
+       pattern, but you want to free the block when they are all done.
+
+       When a pattern is compiled, the reference count field is initialized to
+       zero.  It is changed only by calling this function, whose action is  to
+       add  the  adjust  value  (which may be positive or negative) to it. The
+       yield of the function is the new value. However, the value of the count
+       is  constrained to lie between 0 and 65535, inclusive. If the new value
+       is outside these limits, it is forced to the appropriate limit value.
+
+       Except when it is zero, the reference count is not correctly  preserved
+       if  a  pattern  is  compiled on one host and then transferred to a host
+       whose byte-order is different. (This seems a highly unlikely scenario.)
+
+
+MATCHING A PATTERN: THE TRADITIONAL FUNCTION
+
+       int pcre_exec(const pcre *code, const pcre_extra *extra,
+            const char *subject, int length, int startoffset,
+            int options, int *ovector, int ovecsize);
+
+       The function pcre_exec() is called to match a subject string against  a
+       compiled  pattern, which is passed in the code argument. If the pattern
+       was studied, the result of the study should  be  passed  in  the  extra
+       argument.  You  can call pcre_exec() with the same code and extra argu-
+       ments as many times as you like, in order to  match  different  subject
+       strings with the same pattern.
+
+       This  function  is  the  main  matching facility of the library, and it
+       operates in a Perl-like manner. For specialist use  there  is  also  an
+       alternative  matching function, which is described below in the section
+       about the pcre_dfa_exec() function.
+
+       In most applications, the pattern will have been compiled (and  option-
+       ally  studied)  in the same process that calls pcre_exec(). However, it
+       is possible to save compiled patterns and study data, and then use them
+       later  in  different processes, possibly even on different hosts. For a
+       discussion about this, see the pcreprecompile documentation.
+
+       Here is an example of a simple call to pcre_exec():
+
+         int rc;
+         int ovector[30];
+         rc = pcre_exec(
+           re,             /* result of pcre_compile() */
+           NULL,           /* we didn't study the pattern */
+           "some string",  /* the subject string */
+           11,             /* the length of the subject string */
+           0,              /* start at offset 0 in the subject */
+           0,              /* default options */
+           ovector,        /* vector of integers for substring information */
+           30);            /* number of elements (NOT size in bytes) */
+
+   Extra data for pcre_exec()
+
+       If the extra argument is not NULL, it must point to a  pcre_extra  data
+       block.  The pcre_study() function returns such a block (when it doesn't
+       return NULL), but you can also create one for yourself, and pass  addi-
+       tional  information  in it. The pcre_extra block contains the following
+       fields (not necessarily in this order):
+
+         unsigned long int flags;
+         void *study_data;
+         void *executable_jit;
+         unsigned long int match_limit;
+         unsigned long int match_limit_recursion;
+         void *callout_data;
+         const unsigned char *tables;
+         unsigned char **mark;
+
+       In the 16-bit version of  this  structure,  the  mark  field  has  type
+       "PCRE_UCHAR16 **".
+
+       In  the  32-bit  version  of  this  structure,  the mark field has type
+       "PCRE_UCHAR32 **".
+
+       The flags field is used to specify which of the other fields  are  set.
+       The flag bits are:
+
+         PCRE_EXTRA_CALLOUT_DATA
+         PCRE_EXTRA_EXECUTABLE_JIT
+         PCRE_EXTRA_MARK
+         PCRE_EXTRA_MATCH_LIMIT
+         PCRE_EXTRA_MATCH_LIMIT_RECURSION
+         PCRE_EXTRA_STUDY_DATA
+         PCRE_EXTRA_TABLES
+
+       Other  flag  bits should be set to zero. The study_data field and some-
+       times the executable_jit field are set in the pcre_extra block that  is
+       returned  by pcre_study(), together with the appropriate flag bits. You
+       should not set these yourself, but you may add to the block by  setting
+       other fields and their corresponding flag bits.
+
+       The match_limit field provides a means of preventing PCRE from using up
+       a vast amount of resources when running patterns that are not going  to
+       match,  but  which  have  a very large number of possibilities in their
+       search trees. The classic example is a pattern that uses nested  unlim-
+       ited repeats.
+
+       Internally,  pcre_exec() uses a function called match(), which it calls
+       repeatedly (sometimes recursively). The limit  set  by  match_limit  is
+       imposed  on the number of times this function is called during a match,
+       which has the effect of limiting the amount of  backtracking  that  can
+       take place. For patterns that are not anchored, the count restarts from
+       zero for each position in the subject string.
+
+       When pcre_exec() is called with a pattern that was successfully studied
+       with  a  JIT  option, the way that the matching is executed is entirely
+       different.  However, there is still the possibility of runaway matching
+       that goes on for a very long time, and so the match_limit value is also
+       used in this case (but in a different way) to limit how long the match-
+       ing can continue.
+
+       The  default  value  for  the  limit can be set when PCRE is built; the
+       default default is 10 million, which handles all but the  most  extreme
+       cases.  You  can  override  the  default by suppling pcre_exec() with a
+       pcre_extra    block    in    which    match_limit    is    set,     and
+       PCRE_EXTRA_MATCH_LIMIT  is  set  in  the  flags  field. If the limit is
+       exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
+
+       A value for the match limit may also be supplied  by  an  item  at  the
+       start of a pattern of the form
+
+         (*LIMIT_MATCH=d)
+
+       where  d is a decimal number. However, such a setting is ignored unless
+       d is less than the limit set by the caller of  pcre_exec()  or,  if  no
+       such limit is set, less than the default.
+
+       The  match_limit_recursion field is similar to match_limit, but instead
+       of limiting the total number of times that match() is called, it limits
+       the  depth  of  recursion. The recursion depth is a smaller number than
+       the total number of calls, because not all calls to match() are  recur-
+       sive.  This limit is of use only if it is set smaller than match_limit.
+
+       Limiting  the  recursion  depth limits the amount of machine stack that
+       can be used, or, when PCRE has been compiled to use memory on the  heap
+       instead  of the stack, the amount of heap memory that can be used. This
+       limit is not relevant, and is ignored, when matching is done using  JIT
+       compiled code.
+
+       The  default  value  for  match_limit_recursion can be set when PCRE is
+       built; the default default  is  the  same  value  as  the  default  for
+       match_limit.  You can override the default by suppling pcre_exec() with
+       a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and
+       PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the
+       limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
+
+       A value for the recursion limit may also be supplied by an item at  the
+       start of a pattern of the form
+
+         (*LIMIT_RECURSION=d)
+
+       where  d is a decimal number. However, such a setting is ignored unless
+       d is less than the limit set by the caller of  pcre_exec()  or,  if  no
+       such limit is set, less than the default.
+
+       The  callout_data  field is used in conjunction with the "callout" fea-
+       ture, and is described in the pcrecallout documentation.
+
+       The tables field is provided for use with patterns that have been  pre-
+       compiled using custom character tables, saved to disc or elsewhere, and
+       then reloaded, because the tables that were used to compile  a  pattern
+       are  not saved with it. See the pcreprecompile documentation for a dis-
+       cussion of saving compiled patterns for later use. If  NULL  is  passed
+       using this mechanism, it forces PCRE's internal tables to be used.
+
+       Warning:  The  tables  that  pcre_exec() uses must be the same as those
+       that were used when the pattern was compiled. If this is not the  case,
+       the behaviour of pcre_exec() is undefined. Therefore, when a pattern is
+       compiled and matched in the same process, this field  should  never  be
+       set. In this (the most common) case, the correct table pointer is auto-
+       matically passed with  the  compiled  pattern  from  pcre_compile()  to
+       pcre_exec().
+
+       If  PCRE_EXTRA_MARK  is  set in the flags field, the mark field must be
+       set to point to a suitable variable. If the pattern contains any  back-
+       tracking  control verbs such as (*MARK:NAME), and the execution ends up
+       with a name to pass back, a pointer to the  name  string  (zero  termi-
+       nated)  is  placed  in  the  variable pointed to by the mark field. The
+       names are within the compiled pattern; if you wish  to  retain  such  a
+       name  you must copy it before freeing the memory of a compiled pattern.
+       If there is no name to pass back, the variable pointed to by  the  mark
+       field  is  set  to NULL. For details of the backtracking control verbs,
+       see the section entitled "Backtracking control" in the pcrepattern doc-
+       umentation.
+
+   Option bits for pcre_exec()
+
+       The  unused  bits of the options argument for pcre_exec() must be zero.
+       The only bits that may  be  set  are  PCRE_ANCHORED,  PCRE_NEWLINE_xxx,
+       PCRE_NOTBOL,    PCRE_NOTEOL,    PCRE_NOTEMPTY,   PCRE_NOTEMPTY_ATSTART,
+       PCRE_NO_START_OPTIMIZE,  PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,   and
+       PCRE_PARTIAL_SOFT.
+
+       If  the  pattern  was successfully studied with one of the just-in-time
+       (JIT) compile options, the only supported options for JIT execution are
+       PCRE_NO_UTF8_CHECK,     PCRE_NOTBOL,     PCRE_NOTEOL,    PCRE_NOTEMPTY,
+       PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If  an
+       unsupported  option  is  used, JIT execution is disabled and the normal
+       interpretive code in pcre_exec() is run.
+
+         PCRE_ANCHORED
+
+       The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first
+       matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or
+       turned out to be anchored by virtue of its contents, it cannot be  made
+       unachored at matching time.
+
+         PCRE_BSR_ANYCRLF
+         PCRE_BSR_UNICODE
+
+       These options (which are mutually exclusive) control what the \R escape
+       sequence matches. The choice is either to match only CR, LF,  or  CRLF,
+       or  to  match  any Unicode newline sequence. These options override the
+       choice that was made or defaulted when the pattern was compiled.
+
+         PCRE_NEWLINE_CR
+         PCRE_NEWLINE_LF
+         PCRE_NEWLINE_CRLF
+         PCRE_NEWLINE_ANYCRLF
+         PCRE_NEWLINE_ANY
+
+       These options override  the  newline  definition  that  was  chosen  or
+       defaulted  when the pattern was compiled. For details, see the descrip-
+       tion of pcre_compile()  above.  During  matching,  the  newline  choice
+       affects  the  behaviour  of the dot, circumflex, and dollar metacharac-
+       ters. It may also alter the way the match position is advanced after  a
+       match failure for an unanchored pattern.
+
+       When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is
+       set, and a match attempt for an unanchored pattern fails when the  cur-
+       rent  position  is  at  a  CRLF  sequence,  and the pattern contains no
+       explicit matches for  CR  or  LF  characters,  the  match  position  is
+       advanced by two characters instead of one, in other words, to after the
+       CRLF.
+
+       The above rule is a compromise that makes the most common cases work as
+       expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL
+       option is not set), it does not match the string "\r\nA" because, after
+       failing  at the start, it skips both the CR and the LF before retrying.
+       However, the pattern [\r\n]A does match that string,  because  it  con-
+       tains an explicit CR or LF reference, and so advances only by one char-
+       acter after the first failure.
+
+       An explicit match for CR of LF is either a literal appearance of one of
+       those  characters,  or  one  of the \r or \n escape sequences. Implicit
+       matches such as [^X] do not count, nor does \s (which includes  CR  and
+       LF in the characters that it matches).
+
+       Notwithstanding  the above, anomalous effects may still occur when CRLF
+       is a valid newline sequence and explicit \r or \n escapes appear in the
+       pattern.
+
+         PCRE_NOTBOL
+
+       This option specifies that first character of the subject string is not
+       the beginning of a line, so the  circumflex  metacharacter  should  not
+       match  before it. Setting this without PCRE_MULTILINE (at compile time)
+       causes circumflex never to match. This option affects only  the  behav-
+       iour of the circumflex metacharacter. It does not affect \A.
+
+         PCRE_NOTEOL
+
+       This option specifies that the end of the subject string is not the end
+       of a line, so the dollar metacharacter should not match it nor  (except
+       in  multiline mode) a newline immediately before it. Setting this with-
+       out PCRE_MULTILINE (at compile time) causes dollar never to match. This
+       option  affects only the behaviour of the dollar metacharacter. It does
+       not affect \Z or \z.
+
+         PCRE_NOTEMPTY
+
+       An empty string is not considered to be a valid match if this option is
+       set.  If  there are alternatives in the pattern, they are tried. If all
+       the alternatives match the empty string, the entire  match  fails.  For
+       example, if the pattern
+
+         a?b?
+
+       is  applied  to  a  string not beginning with "a" or "b", it matches an
+       empty string at the start of the subject. With PCRE_NOTEMPTY set,  this
+       match is not valid, so PCRE searches further into the string for occur-
+       rences of "a" or "b".
+
+         PCRE_NOTEMPTY_ATSTART
+
+       This is like PCRE_NOTEMPTY, except that an empty string match  that  is
+       not  at  the  start  of  the  subject  is  permitted. If the pattern is
+       anchored, such a match can occur only if the pattern contains \K.
+
+       Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or
+       PCRE_NOTEMPTY_ATSTART,  but  it  does  make a special case of a pattern
+       match of the empty string within its split() function, and  when  using
+       the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after
+       matching a null string by first trying the match again at the same off-
+       set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that
+       fails, by advancing the starting offset (see below) and trying an ordi-
+       nary  match  again. There is some code that demonstrates how to do this
+       in the pcredemo sample program. In the most general case, you  have  to
+       check  to  see  if the newline convention recognizes CRLF as a newline,
+       and if so, and the current character is CR followed by LF, advance  the
+       starting offset by two characters instead of one.
+
+         PCRE_NO_START_OPTIMIZE
+
+       There  are a number of optimizations that pcre_exec() uses at the start
+       of a match, in order to speed up the process. For  example,  if  it  is
+       known that an unanchored match must start with a specific character, it
+       searches the subject for that character, and fails  immediately  if  it
+       cannot  find  it,  without actually running the main matching function.
+       This means that a special item such as (*COMMIT) at the start of a pat-
+       tern  is  not  considered until after a suitable starting point for the
+       match has been found. Also, when callouts or (*MARK) items are in  use,
+       these "start-up" optimizations can cause them to be skipped if the pat-
+       tern is never actually used. The start-up optimizations are in effect a
+       pre-scan of the subject that takes place before the pattern is run.
+
+       The  PCRE_NO_START_OPTIMIZE option disables the start-up optimizations,
+       possibly causing performance to suffer,  but  ensuring  that  in  cases
+       where  the  result is "no match", the callouts do occur, and that items
+       such as (*COMMIT) and (*MARK) are considered at every possible starting
+       position  in  the  subject  string. If PCRE_NO_START_OPTIMIZE is set at
+       compile time,  it  cannot  be  unset  at  matching  time.  The  use  of
+       PCRE_NO_START_OPTIMIZE  at  matching  time  (that  is,  passing  it  to
+       pcre_exec()) disables JIT execution; in  this  situation,  matching  is
+       always done using interpretively.
+
+       Setting  PCRE_NO_START_OPTIMIZE  can  change  the outcome of a matching
+       operation.  Consider the pattern
+
+         (*COMMIT)ABC
+
+       When this is compiled, PCRE records the fact that a  match  must  start
+       with  the  character  "A".  Suppose the subject string is "DEFABC". The
+       start-up optimization scans along the subject, finds "A" and  runs  the
+       first  match attempt from there. The (*COMMIT) item means that the pat-
+       tern must match the current starting position, which in this  case,  it
+       does.  However,  if  the  same match is run with PCRE_NO_START_OPTIMIZE
+       set, the initial scan along the subject string  does  not  happen.  The
+       first  match  attempt  is  run  starting  from "D" and when this fails,
+       (*COMMIT) prevents any further matches  being  tried,  so  the  overall
+       result  is  "no  match". If the pattern is studied, more start-up opti-
+       mizations may be used. For example, a minimum length  for  the  subject
+       may be recorded. Consider the pattern
+
+         (*MARK:A)(X|Y)
+
+       The  minimum  length  for  a  match is one character. If the subject is
+       "ABC", there will be attempts to  match  "ABC",  "BC",  "C",  and  then
+       finally  an empty string.  If the pattern is studied, the final attempt
+       does not take place, because PCRE knows that the subject is too  short,
+       and  so  the  (*MARK) is never encountered.  In this case, studying the
+       pattern does not affect the overall match result, which  is  still  "no
+       match", but it does affect the auxiliary information that is returned.
+
+         PCRE_NO_UTF8_CHECK
+
+       When PCRE_UTF8 is set at compile time, the validity of the subject as a
+       UTF-8 string is automatically checked when pcre_exec() is  subsequently
+       called.  The entire string is checked before any other processing takes
+       place. The value of startoffset is  also  checked  to  ensure  that  it
+       points  to  the start of a UTF-8 character. There is a discussion about
+       the validity of UTF-8 strings in the pcreunicode page.  If  an  invalid
+       sequence   of   bytes   is   found,   pcre_exec()   returns  the  error
+       PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
+       truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
+       both cases, information about the precise nature of the error may  also
+       be  returned (see the descriptions of these errors in the section enti-
+       tled Error return values from pcre_exec() below).  If startoffset  con-
+       tains a value that does not point to the start of a UTF-8 character (or
+       to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
+
+       If you already know that your subject is valid, and you  want  to  skip
+       these    checks    for   performance   reasons,   you   can   set   the
+       PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might  want  to
+       do  this  for the second and subsequent calls to pcre_exec() if you are
+       making repeated calls to find all  the  matches  in  a  single  subject
+       string.  However,  you  should  be  sure  that the value of startoffset
+       points to the start of a character (or the end of  the  subject).  When
+       PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a
+       subject or an invalid value of startoffset is undefined.  Your  program
+       may crash or loop.
+
+         PCRE_PARTIAL_HARD
+         PCRE_PARTIAL_SOFT
+
+       These  options turn on the partial matching feature. For backwards com-
+       patibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A  partial
+       match  occurs if the end of the subject string is reached successfully,
+       but there are not enough subject characters to complete the  match.  If
+       this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
+       matching continues by testing any remaining alternatives.  Only  if  no
+       complete  match  can be found is PCRE_ERROR_PARTIAL returned instead of
+       PCRE_ERROR_NOMATCH. In other words,  PCRE_PARTIAL_SOFT  says  that  the
+       caller  is  prepared to handle a partial match, but only if no complete
+       match can be found.
+
+       If PCRE_PARTIAL_HARD is set, it overrides  PCRE_PARTIAL_SOFT.  In  this
+       case,  if  a  partial  match  is found, pcre_exec() immediately returns
+       PCRE_ERROR_PARTIAL, without  considering  any  other  alternatives.  In
+       other  words, when PCRE_PARTIAL_HARD is set, a partial match is consid-
+       ered to be more important that an alternative complete match.
+
+       In both cases, the portion of the string that was  inspected  when  the
+       partial match was found is set as the first matching string. There is a
+       more detailed discussion of partial and  multi-segment  matching,  with
+       examples, in the pcrepartial documentation.
+
+   The string to be matched by pcre_exec()
+
+       The  subject string is passed to pcre_exec() as a pointer in subject, a
+       length in length, and a starting offset in startoffset. The  units  for
+       length  and  startoffset  are  bytes for the 8-bit library, 16-bit data
+       items for the 16-bit library, and 32-bit  data  items  for  the  32-bit
+       library.
+
+       If  startoffset  is negative or greater than the length of the subject,
+       pcre_exec() returns PCRE_ERROR_BADOFFSET. When the starting  offset  is
+       zero,  the  search  for a match starts at the beginning of the subject,
+       and this is by far the most common case. In UTF-8 or UTF-16  mode,  the
+       offset  must  point to the start of a character, or the end of the sub-
+       ject (in UTF-32 mode, one data unit equals one character, so  all  off-
+       sets  are  valid).  Unlike  the pattern string, the subject may contain
+       binary zeroes.
+
+       A non-zero starting offset is useful when searching for  another  match
+       in  the same subject by calling pcre_exec() again after a previous suc-
+       cess.  Setting startoffset differs from just passing over  a  shortened
+       string  and  setting  PCRE_NOTBOL  in the case of a pattern that begins
+       with any kind of lookbehind. For example, consider the pattern
+
+         \Biss\B
+
+       which finds occurrences of "iss" in the middle of  words.  (\B  matches
+       only  if  the  current position in the subject is not a word boundary.)
+       When applied to the string "Mississipi" the first call  to  pcre_exec()
+       finds  the  first  occurrence. If pcre_exec() is called again with just
+       the remainder of the subject,  namely  "issipi",  it  does  not  match,
+       because \B is always false at the start of the subject, which is deemed
+       to be a word boundary. However, if pcre_exec()  is  passed  the  entire
+       string again, but with startoffset set to 4, it finds the second occur-
+       rence of "iss" because it is able to look behind the starting point  to
+       discover that it is preceded by a letter.
+
+       Finding  all  the  matches  in a subject is tricky when the pattern can
+       match an empty string. It is possible to emulate Perl's /g behaviour by
+       first   trying   the   match   again  at  the  same  offset,  with  the
+       PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED  options,  and  then  if  that
+       fails,  advancing  the  starting  offset  and  trying an ordinary match
+       again. There is some code that demonstrates how to do this in the pcre-
+       demo sample program. In the most general case, you have to check to see
+       if the newline convention recognizes CRLF as a newline, and if so,  and
+       the current character is CR followed by LF, advance the starting offset
+       by two characters instead of one.
+
+       If a non-zero starting offset is passed when the pattern  is  anchored,
+       one attempt to match at the given offset is made. This can only succeed
+       if the pattern does not require the match to be at  the  start  of  the
+       subject.
+
+   How pcre_exec() returns captured substrings
+
+       In  general, a pattern matches a certain portion of the subject, and in
+       addition, further substrings from the subject  may  be  picked  out  by
+       parts  of  the  pattern.  Following the usage in Jeffrey Friedl's book,
+       this is called "capturing" in what follows, and the  phrase  "capturing
+       subpattern"  is  used for a fragment of a pattern that picks out a sub-
+       string. PCRE supports several other kinds of  parenthesized  subpattern
+       that do not cause substrings to be captured.
+
+       Captured substrings are returned to the caller via a vector of integers
+       whose address is passed in ovector. The number of elements in the  vec-
+       tor  is  passed in ovecsize, which must be a non-negative number. Note:
+       this argument is NOT the size of ovector in bytes.
+
+       The first two-thirds of the vector is used to pass back  captured  sub-
+       strings,  each  substring using a pair of integers. The remaining third
+       of the vector is used as workspace by pcre_exec() while  matching  cap-
+       turing  subpatterns, and is not available for passing back information.
+       The number passed in ovecsize should always be a multiple of three.  If
+       it is not, it is rounded down.
+
+       When  a  match  is successful, information about captured substrings is
+       returned in pairs of integers, starting at the  beginning  of  ovector,
+       and  continuing  up  to two-thirds of its length at the most. The first
+       element of each pair is set to the offset of the first character  in  a
+       substring,  and  the second is set to the offset of the first character
+       after the end of a substring. These values are always  data  unit  off-
+       sets,  even  in  UTF  mode. They are byte offsets in the 8-bit library,
+       16-bit data item offsets in the 16-bit library, and  32-bit  data  item
+       offsets in the 32-bit library. Note: they are not character counts.
+
+       The  first  pair  of  integers, ovector[0] and ovector[1], identify the
+       portion of the subject string matched by the entire pattern.  The  next
+       pair  is  used for the first capturing subpattern, and so on. The value
+       returned by pcre_exec() is one more than the highest numbered pair that
+       has  been  set.  For example, if two substrings have been captured, the
+       returned value is 3. If there are no capturing subpatterns, the  return
+       value from a successful match is 1, indicating that just the first pair
+       of offsets has been set.
+
+       If a capturing subpattern is matched repeatedly, it is the last portion
+       of the string that it matched that is returned.
+
+       If  the vector is too small to hold all the captured substring offsets,
+       it is used as far as possible (up to two-thirds of its length), and the
+       function  returns a value of zero. If neither the actual string matched
+       nor any captured substrings are of interest, pcre_exec() may be  called
+       with  ovector passed as NULL and ovecsize as zero. However, if the pat-
+       tern contains back references and the ovector  is  not  big  enough  to
+       remember  the related substrings, PCRE has to get additional memory for
+       use during matching. Thus it is usually advisable to supply an  ovector
+       of reasonable size.
+
+       There  are  some  cases where zero is returned (indicating vector over-
+       flow) when in fact the vector is exactly the right size for  the  final
+       match. For example, consider the pattern
+
+         (a)(?:(b)c|bd)
+
+       If  a  vector of 6 elements (allowing for only 1 captured substring) is
+       given with subject string "abd", pcre_exec() will try to set the second
+       captured string, thereby recording a vector overflow, before failing to
+       match "c" and backing up  to  try  the  second  alternative.  The  zero
+       return,  however,  does  correctly  indicate that the maximum number of
+       slots (namely 2) have been filled. In similar cases where there is tem-
+       porary  overflow,  but  the final number of used slots is actually less
+       than the maximum, a non-zero value is returned.
+
+       The pcre_fullinfo() function can be used to find out how many capturing
+       subpatterns  there  are  in  a  compiled pattern. The smallest size for
+       ovector that will allow for n captured substrings, in addition  to  the
+       offsets of the substring matched by the whole pattern, is (n+1)*3.
+
+       It  is  possible for capturing subpattern number n+1 to match some part
+       of the subject when subpattern n has not been used at all. For example,
+       if  the  string  "abc"  is  matched against the pattern (a|(z))(bc) the
+       return from the function is 4, and subpatterns 1 and 3 are matched, but
+       2  is  not.  When  this happens, both values in the offset pairs corre-
+       sponding to unused subpatterns are set to -1.
+
+       Offset values that correspond to unused subpatterns at the end  of  the
+       expression  are  also  set  to  -1. For example, if the string "abc" is
+       matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are  not
+       matched.  The  return  from the function is 2, because the highest used
+       capturing subpattern number is 1, and the offsets for  for  the  second
+       and  third  capturing subpatterns (assuming the vector is large enough,
+       of course) are set to -1.
+
+       Note: Elements in the first two-thirds of ovector that  do  not  corre-
+       spond  to  capturing parentheses in the pattern are never changed. That
+       is, if a pattern contains n capturing parentheses, no more  than  ovec-
+       tor[0]  to ovector[2n+1] are set by pcre_exec(). The other elements (in
+       the first two-thirds) retain whatever values they previously had.
+
+       Some convenience functions are provided  for  extracting  the  captured
+       substrings as separate strings. These are described below.
+
+   Error return values from pcre_exec()
+
+       If  pcre_exec()  fails, it returns a negative number. The following are
+       defined in the header file:
+
+         PCRE_ERROR_NOMATCH        (-1)
+
+       The subject string did not match the pattern.
+
+         PCRE_ERROR_NULL           (-2)
+
+       Either code or subject was passed as NULL,  or  ovector  was  NULL  and
+       ovecsize was not zero.
+
+         PCRE_ERROR_BADOPTION      (-3)
+
+       An unrecognized bit was set in the options argument.
+
+         PCRE_ERROR_BADMAGIC       (-4)
+
+       PCRE  stores a 4-byte "magic number" at the start of the compiled code,
+       to catch the case when it is passed a junk pointer and to detect when a
+       pattern that was compiled in an environment of one endianness is run in
+       an environment with the other endianness. This is the error  that  PCRE
+       gives when the magic number is not present.
+
+         PCRE_ERROR_UNKNOWN_OPCODE (-5)
+
+       While running the pattern match, an unknown item was encountered in the
+       compiled pattern. This error could be caused by a bug  in  PCRE  or  by
+       overwriting of the compiled pattern.
+
+         PCRE_ERROR_NOMEMORY       (-6)
+
+       If  a  pattern contains back references, but the ovector that is passed
+       to pcre_exec() is not big enough to remember the referenced substrings,
+       PCRE  gets  a  block of memory at the start of matching to use for this
+       purpose. If the call via pcre_malloc() fails, this error is given.  The
+       memory is automatically freed at the end of matching.
+
+       This  error  is also given if pcre_stack_malloc() fails in pcre_exec().
+       This can happen only when PCRE has been compiled with  --disable-stack-
+       for-recursion.
+
+         PCRE_ERROR_NOSUBSTRING    (-7)
+
+       This  error is used by the pcre_copy_substring(), pcre_get_substring(),
+       and  pcre_get_substring_list()  functions  (see  below).  It  is  never
+       returned by pcre_exec().
+
+         PCRE_ERROR_MATCHLIMIT     (-8)
+
+       The  backtracking  limit,  as  specified  by the match_limit field in a
+       pcre_extra structure (or defaulted) was reached.  See  the  description
+       above.
+
+         PCRE_ERROR_CALLOUT        (-9)
+
+       This error is never generated by pcre_exec() itself. It is provided for
+       use by callout functions that want to yield a distinctive  error  code.
+       See the pcrecallout documentation for details.
+
+         PCRE_ERROR_BADUTF8        (-10)
+
+       A  string  that contains an invalid UTF-8 byte sequence was passed as a
+       subject, and the PCRE_NO_UTF8_CHECK option was not set. If the size  of
+       the  output  vector  (ovecsize)  is  at least 2, the byte offset to the
+       start of the the invalid UTF-8 character is placed in  the  first  ele-
+       ment,  and  a  reason  code is placed in the second element. The reason
+       codes are listed in the following section.  For backward compatibility,
+       if  PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8 char-
+       acter  at  the  end  of  the   subject   (reason   codes   1   to   5),
+       PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
+
+         PCRE_ERROR_BADUTF8_OFFSET (-11)
+
+       The  UTF-8  byte  sequence that was passed as a subject was checked and
+       found to be valid (the PCRE_NO_UTF8_CHECK option was not set), but  the
+       value  of startoffset did not point to the beginning of a UTF-8 charac-
+       ter or the end of the subject.
+
+         PCRE_ERROR_PARTIAL        (-12)
+
+       The subject string did not match, but it did match partially.  See  the
+       pcrepartial documentation for details of partial matching.
+
+         PCRE_ERROR_BADPARTIAL     (-13)
+
+       This  code  is  no  longer  in  use.  It was formerly returned when the
+       PCRE_PARTIAL option was used with a compiled pattern  containing  items
+       that  were  not  supported  for  partial  matching.  From  release 8.00
+       onwards, there are no restrictions on partial matching.
+
+         PCRE_ERROR_INTERNAL       (-14)
+
+       An unexpected internal error has occurred. This error could  be  caused
+       by a bug in PCRE or by overwriting of the compiled pattern.
+
+         PCRE_ERROR_BADCOUNT       (-15)
+
+       This error is given if the value of the ovecsize argument is negative.
+
+         PCRE_ERROR_RECURSIONLIMIT (-21)
+
+       The internal recursion limit, as specified by the match_limit_recursion
+       field in a pcre_extra structure (or defaulted)  was  reached.  See  the
+       description above.
+
+         PCRE_ERROR_BADNEWLINE     (-23)
+
+       An invalid combination of PCRE_NEWLINE_xxx options was given.
+
+         PCRE_ERROR_BADOFFSET      (-24)
+
+       The value of startoffset was negative or greater than the length of the
+       subject, that is, the value in length.
+
+         PCRE_ERROR_SHORTUTF8      (-25)
+
+       This error is returned instead of PCRE_ERROR_BADUTF8 when  the  subject
+       string  ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD
+       option is set.  Information  about  the  failure  is  returned  as  for
+       PCRE_ERROR_BADUTF8.  It  is in fact sufficient to detect this case, but
+       this special error code for PCRE_PARTIAL_HARD precedes the  implementa-
+       tion  of returned information; it is retained for backwards compatibil-
+       ity.
+
+         PCRE_ERROR_RECURSELOOP    (-26)
+
+       This error is returned when pcre_exec() detects a recursion loop within
+       the  pattern. Specifically, it means that either the whole pattern or a
+       subpattern has been called recursively for the second time at the  same
+       position in the subject string. Some simple patterns that might do this
+       are detected and faulted at compile time, but more  complicated  cases,
+       in particular mutual recursions between two different subpatterns, can-
+       not be detected until run time.
+
+         PCRE_ERROR_JIT_STACKLIMIT (-27)
+
+       This error is returned when a pattern  that  was  successfully  studied
+       using  a  JIT compile option is being matched, but the memory available
+       for the just-in-time processing stack is  not  large  enough.  See  the
+       pcrejit documentation for more details.
+
+         PCRE_ERROR_BADMODE        (-28)
+
+       This error is given if a pattern that was compiled by the 8-bit library
+       is passed to a 16-bit or 32-bit library function, or vice versa.
+
+         PCRE_ERROR_BADENDIANNESS  (-29)
+
+       This error is given if  a  pattern  that  was  compiled  and  saved  is
+       reloaded  on  a  host  with  different endianness. The utility function
+       pcre_pattern_to_host_byte_order() can be used to convert such a pattern
+       so that it runs on the new host.
+
+         PCRE_ERROR_JIT_BADOPTION
+
+       This  error  is  returned  when a pattern that was successfully studied
+       using a JIT compile option is being  matched,  but  the  matching  mode
+       (partial  or complete match) does not correspond to any JIT compilation
+       mode. When the JIT fast path function is used, this error may  be  also
+       given  for  invalid  options.  See  the  pcrejit documentation for more
+       details.
+
+         PCRE_ERROR_BADLENGTH      (-32)
+
+       This error is given if pcre_exec() is called with a negative value  for
+       the length argument.
+
+       Error numbers -16 to -20, -22, and 30 are not used by pcre_exec().
+
+   Reason codes for invalid UTF-8 strings
+
+       This  section  applies  only  to  the  8-bit library. The corresponding
+       information for the 16-bit and 32-bit libraries is given in the  pcre16
+       and pcre32 pages.
+
+       When pcre_exec() returns either PCRE_ERROR_BADUTF8 or PCRE_ERROR_SHORT-
+       UTF8, and the size of the output vector (ovecsize) is at least  2,  the
+       offset  of  the  start  of the invalid UTF-8 character is placed in the
+       first output vector element (ovector[0]) and a reason code is placed in
+       the  second  element  (ovector[1]). The reason codes are given names in
+       the pcre.h header file:
+
+         PCRE_UTF8_ERR1
+         PCRE_UTF8_ERR2
+         PCRE_UTF8_ERR3
+         PCRE_UTF8_ERR4
+         PCRE_UTF8_ERR5
+
+       The string ends with a truncated UTF-8 character;  the  code  specifies
+       how  many bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8
+       characters to be no longer than 4 bytes, the  encoding  scheme  (origi-
+       nally  defined  by  RFC  2279)  allows  for  up to 6 bytes, and this is
+       checked first; hence the possibility of 4 or 5 missing bytes.
+
+         PCRE_UTF8_ERR6
+         PCRE_UTF8_ERR7
+         PCRE_UTF8_ERR8
+         PCRE_UTF8_ERR9
+         PCRE_UTF8_ERR10
+
+       The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of
+       the  character  do  not have the binary value 0b10 (that is, either the
+       most significant bit is 0, or the next bit is 1).
+
+         PCRE_UTF8_ERR11
+         PCRE_UTF8_ERR12
+
+       A character that is valid by the RFC 2279 rules is either 5 or 6  bytes
+       long; these code points are excluded by RFC 3629.
+
+         PCRE_UTF8_ERR13
+
+       A  4-byte character has a value greater than 0x10fff; these code points
+       are excluded by RFC 3629.
+
+         PCRE_UTF8_ERR14
+
+       A 3-byte character has a value in the  range  0xd800  to  0xdfff;  this
+       range  of code points are reserved by RFC 3629 for use with UTF-16, and
+       so are excluded from UTF-8.
+
+         PCRE_UTF8_ERR15
+         PCRE_UTF8_ERR16
+         PCRE_UTF8_ERR17
+         PCRE_UTF8_ERR18
+         PCRE_UTF8_ERR19
+
+       A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it  codes
+       for  a  value that can be represented by fewer bytes, which is invalid.
+       For example, the two bytes 0xc0, 0xae give the value 0x2e,  whose  cor-
+       rect coding uses just one byte.
+
+         PCRE_UTF8_ERR20
+
+       The two most significant bits of the first byte of a character have the
+       binary value 0b10 (that is, the most significant bit is 1 and the  sec-
+       ond  is  0). Such a byte can only validly occur as the second or subse-
+       quent byte of a multi-byte character.
+
+         PCRE_UTF8_ERR21
+
+       The first byte of a character has the value 0xfe or 0xff. These  values
+       can never occur in a valid UTF-8 string.
+
+         PCRE_UTF8_ERR22
+
+       This  error  code  was  formerly  used when the presence of a so-called
+       "non-character" caused an error. Unicode corrigendum #9 makes it  clear
+       that  such  characters should not cause a string to be rejected, and so
+       this code is no longer in use and is never returned.
+
+
+EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+
+       int pcre_copy_substring(const char *subject, int *ovector,
+            int stringcount, int stringnumber, char *buffer,
+            int buffersize);
+
+       int pcre_get_substring(const char *subject, int *ovector,
+            int stringcount, int stringnumber,
+            const char **stringptr);
+
+       int pcre_get_substring_list(const char *subject,
+            int *ovector, int stringcount, const char ***listptr);
+
+       Captured substrings can be  accessed  directly  by  using  the  offsets
+       returned  by  pcre_exec()  in  ovector.  For convenience, the functions
+       pcre_copy_substring(),    pcre_get_substring(),    and    pcre_get_sub-
+       string_list()  are  provided for extracting captured substrings as new,
+       separate, zero-terminated strings. These functions identify  substrings
+       by  number.  The  next section describes functions for extracting named
+       substrings.
+
+       A substring that contains a binary zero is correctly extracted and  has
+       a  further zero added on the end, but the result is not, of course, a C
+       string.  However, you can process such a string  by  referring  to  the
+       length  that  is  returned  by  pcre_copy_substring() and pcre_get_sub-
+       string().  Unfortunately, the interface to pcre_get_substring_list() is
+       not  adequate for handling strings containing binary zeros, because the
+       end of the final string is not independently indicated.
+
+       The first three arguments are the same for all  three  of  these  func-
+       tions:  subject  is  the subject string that has just been successfully
+       matched, ovector is a pointer to the vector of integer offsets that was
+       passed to pcre_exec(), and stringcount is the number of substrings that
+       were captured by the match, including the substring  that  matched  the
+       entire regular expression. This is the value returned by pcre_exec() if
+       it is greater than zero. If pcre_exec() returned zero, indicating  that
+       it  ran out of space in ovector, the value passed as stringcount should
+       be the number of elements in the vector divided by three.
+
+       The functions pcre_copy_substring() and pcre_get_substring() extract  a
+       single  substring,  whose  number  is given as stringnumber. A value of
+       zero extracts the substring that matched the  entire  pattern,  whereas
+       higher  values  extract  the  captured  substrings.  For pcre_copy_sub-
+       string(), the string is placed in buffer,  whose  length  is  given  by
+       buffersize,  while  for  pcre_get_substring()  a new block of memory is
+       obtained via pcre_malloc, and its address is  returned  via  stringptr.
+       The  yield  of  the function is the length of the string, not including
+       the terminating zero, or one of these error codes:
+
+         PCRE_ERROR_NOMEMORY       (-6)
+
+       The buffer was too small for pcre_copy_substring(), or the  attempt  to
+       get memory failed for pcre_get_substring().
+
+         PCRE_ERROR_NOSUBSTRING    (-7)
+
+       There is no substring whose number is stringnumber.
+
+       The  pcre_get_substring_list()  function  extracts  all  available sub-
+       strings and builds a list of pointers to them. All this is  done  in  a
+       single block of memory that is obtained via pcre_malloc. The address of
+       the memory block is returned via listptr, which is also  the  start  of
+       the  list  of  string pointers. The end of the list is marked by a NULL
+       pointer. The yield of the function is zero if all  went  well,  or  the
+       error code
+
+         PCRE_ERROR_NOMEMORY       (-6)
+
+       if the attempt to get the memory block failed.
+
+       When  any of these functions encounter a substring that is unset, which
+       can happen when capturing subpattern number n+1 matches  some  part  of
+       the  subject, but subpattern n has not been used at all, they return an
+       empty string. This can be distinguished from a genuine zero-length sub-
+       string  by inspecting the appropriate offset in ovector, which is nega-
+       tive for unset substrings.
+
+       The two convenience functions pcre_free_substring() and  pcre_free_sub-
+       string_list()  can  be  used  to free the memory returned by a previous
+       call  of  pcre_get_substring()  or  pcre_get_substring_list(),  respec-
+       tively.  They  do  nothing  more  than  call the function pointed to by
+       pcre_free, which of course could be called directly from a  C  program.
+       However,  PCRE is used in some situations where it is linked via a spe-
+       cial  interface  to  another  programming  language  that  cannot   use
+       pcre_free  directly;  it is for these cases that the functions are pro-
+       vided.
+
+
+EXTRACTING CAPTURED SUBSTRINGS BY NAME
+
+       int pcre_get_stringnumber(const pcre *code,
+            const char *name);
+
+       int pcre_copy_named_substring(const pcre *code,
+            const char *subject, int *ovector,
+            int stringcount, const char *stringname,
+            char *buffer, int buffersize);
+
+       int pcre_get_named_substring(const pcre *code,
+            const char *subject, int *ovector,
+            int stringcount, const char *stringname,
+            const char **stringptr);
+
+       To extract a substring by name, you first have to find associated  num-
+       ber.  For example, for this pattern
+
+         (a+)b(?\d+)...
+
+       the number of the subpattern called "xxx" is 2. If the name is known to
+       be unique (PCRE_DUPNAMES was not set), you can find the number from the
+       name by calling pcre_get_stringnumber(). The first argument is the com-
+       piled pattern, and the second is the name. The yield of the function is
+       the  subpattern  number,  or PCRE_ERROR_NOSUBSTRING (-7) if there is no
+       subpattern of that name.
+
+       Given the number, you can extract the substring directly, or use one of
+       the functions described in the previous section. For convenience, there
+       are also two functions that do the whole job.
+
+       Most   of   the   arguments    of    pcre_copy_named_substring()    and
+       pcre_get_named_substring()  are  the  same  as  those for the similarly
+       named functions that extract by number. As these are described  in  the
+       previous  section,  they  are not re-described here. There are just two
+       differences:
+
+       First, instead of a substring number, a substring name is  given.  Sec-
+       ond, there is an extra argument, given at the start, which is a pointer
+       to the compiled pattern. This is needed in order to gain access to  the
+       name-to-number translation table.
+
+       These  functions call pcre_get_stringnumber(), and if it succeeds, they
+       then call pcre_copy_substring() or pcre_get_substring(),  as  appropri-
+       ate.  NOTE:  If PCRE_DUPNAMES is set and there are duplicate names, the
+       behaviour may not be what you want (see the next section).
+
+       Warning: If the pattern uses the (?| feature to set up multiple subpat-
+       terns  with  the  same number, as described in the section on duplicate
+       subpattern numbers in the pcrepattern page, you  cannot  use  names  to
+       distinguish  the  different subpatterns, because names are not included
+       in the compiled code. The matching process uses only numbers. For  this
+       reason,  the  use of different names for subpatterns of the same number
+       causes an error at compile time.
+
+
+DUPLICATE SUBPATTERN NAMES
+
+       int pcre_get_stringtable_entries(const pcre *code,
+            const char *name, char **first, char **last);
+
+       When a pattern is compiled with the  PCRE_DUPNAMES  option,  names  for
+       subpatterns  are not required to be unique. (Duplicate names are always
+       allowed for subpatterns with the same number, created by using the  (?|
+       feature.  Indeed,  if  such subpatterns are named, they are required to
+       use the same names.)
+
+       Normally, patterns with duplicate names are such that in any one match,
+       only  one of the named subpatterns participates. An example is shown in
+       the pcrepattern documentation.
+
+       When   duplicates   are   present,   pcre_copy_named_substring()    and
+       pcre_get_named_substring()  return the first substring corresponding to
+       the given name that is set. If  none  are  set,  PCRE_ERROR_NOSUBSTRING
+       (-7)  is  returned;  no  data  is returned. The pcre_get_stringnumber()
+       function returns one of the numbers that are associated with the  name,
+       but it is not defined which it is.
+
+       If  you want to get full details of all captured substrings for a given
+       name, you must use  the  pcre_get_stringtable_entries()  function.  The
+       first argument is the compiled pattern, and the second is the name. The
+       third and fourth are pointers to variables which  are  updated  by  the
+       function. After it has run, they point to the first and last entries in
+       the name-to-number table  for  the  given  name.  The  function  itself
+       returns  the  length  of  each entry, or PCRE_ERROR_NOSUBSTRING (-7) if
+       there are none. The format of the table is described above in the  sec-
+       tion  entitled  Information about a pattern above.  Given all the rele-
+       vant entries for the name, you can extract each of their  numbers,  and
+       hence the captured data, if any.
+
+
+FINDING ALL POSSIBLE MATCHES
+
+       The  traditional  matching  function  uses a similar algorithm to Perl,
+       which stops when it finds the first match, starting at a given point in
+       the  subject.  If you want to find all possible matches, or the longest
+       possible match, consider using the alternative matching  function  (see
+       below)  instead.  If you cannot use the alternative function, but still
+       need to find all possible matches, you can kludge it up by  making  use
+       of the callout facility, which is described in the pcrecallout documen-
+       tation.
+
+       What you have to do is to insert a callout right at the end of the pat-
+       tern.   When your callout function is called, extract and save the cur-
+       rent matched substring. Then return  1,  which  forces  pcre_exec()  to
+       backtrack  and  try other alternatives. Ultimately, when it runs out of
+       matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.
+
+
+OBTAINING AN ESTIMATE OF STACK USAGE
+
+       Matching certain patterns using pcre_exec() can use a  lot  of  process
+       stack,  which  in  certain  environments can be rather limited in size.
+       Some users find it helpful to have an estimate of the amount  of  stack
+       that  is  used  by  pcre_exec(),  to help them set recursion limits, as
+       described in the pcrestack documentation. The estimate that  is  output
+       by pcretest when called with the -m and -C options is obtained by call-
+       ing pcre_exec with the values NULL, NULL, NULL, -999, and -999 for  its
+       first five arguments.
+
+       Normally,  if  its  first  argument  is  NULL,  pcre_exec() immediately
+       returns the negative error code PCRE_ERROR_NULL, but with this  special
+       combination  of  arguments,  it returns instead a negative number whose
+       absolute value is the approximate stack frame size in bytes.  (A  nega-
+       tive  number  is  used so that it is clear that no match has happened.)
+       The value is approximate because in  some  cases,  recursive  calls  to
+       pcre_exec() occur when there are one or two additional variables on the
+       stack.
+
+       If PCRE has been compiled to use the heap  instead  of  the  stack  for
+       recursion,  the  value  returned  is  the  size  of  each block that is
+       obtained from the heap.
+
+
+MATCHING A PATTERN: THE ALTERNATIVE FUNCTION
+
+       int pcre_dfa_exec(const pcre *code, const pcre_extra *extra,
+            const char *subject, int length, int startoffset,
+            int options, int *ovector, int ovecsize,
+            int *workspace, int wscount);
+
+       The function pcre_dfa_exec()  is  called  to  match  a  subject  string
+       against  a  compiled pattern, using a matching algorithm that scans the
+       subject string just once, and does not backtrack.  This  has  different
+       characteristics  to  the  normal  algorithm, and is not compatible with
+       Perl. Some of the features of PCRE patterns are not  supported.  Never-
+       theless,  there are times when this kind of matching can be useful. For
+       a discussion of the two matching algorithms, and  a  list  of  features
+       that  pcre_dfa_exec() does not support, see the pcrematching documenta-
+       tion.
+
+       The arguments for the pcre_dfa_exec() function  are  the  same  as  for
+       pcre_exec(), plus two extras. The ovector argument is used in a differ-
+       ent way, and this is described below. The other  common  arguments  are
+       used  in  the  same way as for pcre_exec(), so their description is not
+       repeated here.
+
+       The two additional arguments provide workspace for  the  function.  The
+       workspace  vector  should  contain at least 20 elements. It is used for
+       keeping  track  of  multiple  paths  through  the  pattern  tree.  More
+       workspace  will  be  needed for patterns and subjects where there are a
+       lot of potential matches.
+
+       Here is an example of a simple call to pcre_dfa_exec():
+
+         int rc;
+         int ovector[10];
+         int wspace[20];
+         rc = pcre_dfa_exec(
+           re,             /* result of pcre_compile() */
+           NULL,           /* we didn't study the pattern */
+           "some string",  /* the subject string */
+           11,             /* the length of the subject string */
+           0,              /* start at offset 0 in the subject */
+           0,              /* default options */
+           ovector,        /* vector of integers for substring information */
+           10,             /* number of elements (NOT size in bytes) */
+           wspace,         /* working space vector */
+           20);            /* number of elements (NOT size in bytes) */
+
+   Option bits for pcre_dfa_exec()
+
+       The unused bits of the options argument  for  pcre_dfa_exec()  must  be
+       zero.  The  only  bits  that  may  be  set are PCRE_ANCHORED, PCRE_NEW-
+       LINE_xxx,        PCRE_NOTBOL,        PCRE_NOTEOL,        PCRE_NOTEMPTY,
+       PCRE_NOTEMPTY_ATSTART,       PCRE_NO_UTF8_CHECK,      PCRE_BSR_ANYCRLF,
+       PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE, PCRE_PARTIAL_HARD,  PCRE_PAR-
+       TIAL_SOFT,  PCRE_DFA_SHORTEST,  and PCRE_DFA_RESTART.  All but the last
+       four of these are  exactly  the  same  as  for  pcre_exec(),  so  their
+       description is not repeated here.
+
+         PCRE_PARTIAL_HARD
+         PCRE_PARTIAL_SOFT
+
+       These  have the same general effect as they do for pcre_exec(), but the
+       details are slightly  different.  When  PCRE_PARTIAL_HARD  is  set  for
+       pcre_dfa_exec(),  it  returns PCRE_ERROR_PARTIAL if the end of the sub-
+       ject is reached and there is still at least  one  matching  possibility
+       that requires additional characters. This happens even if some complete
+       matches have also been found. When PCRE_PARTIAL_SOFT is set, the return
+       code PCRE_ERROR_NOMATCH is converted into PCRE_ERROR_PARTIAL if the end
+       of the subject is reached, there have been  no  complete  matches,  but
+       there  is  still  at least one matching possibility. The portion of the
+       string that was inspected when the longest partial match was  found  is
+       set  as  the  first  matching  string  in  both cases.  There is a more
+       detailed discussion of partial and multi-segment matching,  with  exam-
+       ples, in the pcrepartial documentation.
+
+         PCRE_DFA_SHORTEST
+
+       Setting  the  PCRE_DFA_SHORTEST option causes the matching algorithm to
+       stop as soon as it has found one match. Because of the way the alterna-
+       tive  algorithm  works, this is necessarily the shortest possible match
+       at the first possible matching point in the subject string.
+
+         PCRE_DFA_RESTART
+
+       When pcre_dfa_exec() returns a partial match, it is possible to call it
+       again,  with  additional  subject characters, and have it continue with
+       the same match. The PCRE_DFA_RESTART option requests this action;  when
+       it  is  set,  the workspace and wscount options must reference the same
+       vector as before because data about the match so far is  left  in  them
+       after a partial match. There is more discussion of this facility in the
+       pcrepartial documentation.
+
+   Successful returns from pcre_dfa_exec()
+
+       When pcre_dfa_exec() succeeds, it may have matched more than  one  sub-
+       string in the subject. Note, however, that all the matches from one run
+       of the function start at the same point in  the  subject.  The  shorter
+       matches  are all initial substrings of the longer matches. For example,
+       if the pattern
+
+         <.*>
+
+       is matched against the string
+
+         This is    no more
+
+       the three matched strings are
+
+         
+          
+           
+
+       On success, the yield of the function is a number  greater  than  zero,
+       which  is  the  number of matched substrings. The substrings themselves
+       are returned in ovector. Each string uses two elements;  the  first  is
+       the  offset  to  the start, and the second is the offset to the end. In
+       fact, all the strings have the same start  offset.  (Space  could  have
+       been  saved by giving this only once, but it was decided to retain some
+       compatibility with the way pcre_exec() returns data,  even  though  the
+       meaning of the strings is different.)
+
+       The strings are returned in reverse order of length; that is, the long-
+       est matching string is given first. If there were too many  matches  to
+       fit  into ovector, the yield of the function is zero, and the vector is
+       filled with the longest matches.  Unlike  pcre_exec(),  pcre_dfa_exec()
+       can use the entire ovector for returning matched strings.
+
+       NOTE:  PCRE's  "auto-possessification"  optimization usually applies to
+       character repeats at the end of a pattern (as well as internally).  For
+       example,  the  pattern "a\d+" is compiled as if it were "a\d++" because
+       there is no point even considering the possibility of backtracking into
+       the  repeated digits. For DFA matching, this means that only one possi-
+       ble match is found. If you really do  want  multiple  matches  in  such
+       cases,   either   use   an   ungreedy   repeat  ("a\d+?")  or  set  the
+       PCRE_NO_AUTO_POSSESS option when compiling.
+
+   Error returns from pcre_dfa_exec()
+
+       The pcre_dfa_exec() function returns a negative number when  it  fails.
+       Many  of  the  errors  are  the  same as for pcre_exec(), and these are
+       described above.  There are in addition the following errors  that  are
+       specific to pcre_dfa_exec():
+
+         PCRE_ERROR_DFA_UITEM      (-16)
+
+       This  return is given if pcre_dfa_exec() encounters an item in the pat-
+       tern that it does not support, for instance, the use of \C  or  a  back
+       reference.
+
+         PCRE_ERROR_DFA_UCOND      (-17)
+
+       This  return  is  given  if pcre_dfa_exec() encounters a condition item
+       that uses a back reference for the condition, or a test  for  recursion
+       in a specific group. These are not supported.
+
+         PCRE_ERROR_DFA_UMLIMIT    (-18)
+
+       This  return  is given if pcre_dfa_exec() is called with an extra block
+       that contains a setting of  the  match_limit  or  match_limit_recursion
+       fields.  This  is  not  supported (these fields are meaningless for DFA
+       matching).
+
+         PCRE_ERROR_DFA_WSSIZE     (-19)
+
+       This return is given if  pcre_dfa_exec()  runs  out  of  space  in  the
+       workspace vector.
+
+         PCRE_ERROR_DFA_RECURSE    (-20)
+
+       When  a  recursive subpattern is processed, the matching function calls
+       itself recursively, using private vectors for  ovector  and  workspace.
+       This  error  is  given  if  the output vector is not large enough. This
+       should be extremely rare, as a vector of size 1000 is used.
+
+         PCRE_ERROR_DFA_BADRESTART (-30)
+
+       When pcre_dfa_exec() is called with the PCRE_DFA_RESTART  option,  some
+       plausibility  checks  are  made on the contents of the workspace, which
+       should contain data about the previous partial match. If any  of  these
+       checks fail, this error is given.
+
+
+SEE ALSO
+
+       pcre16(3),   pcre32(3),  pcrebuild(3),  pcrecallout(3),  pcrecpp(3)(3),
+       pcrematching(3), pcrepartial(3), pcreposix(3), pcreprecompile(3), pcre-
+       sample(3), pcrestack(3).
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 09 February 2014
+       Copyright (c) 1997-2014 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCRECALLOUT(3)             Library Functions Manual             PCRECALLOUT(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+SYNOPSIS
+
+       #include 
+
+       int (*pcre_callout)(pcre_callout_block *);
+
+       int (*pcre16_callout)(pcre16_callout_block *);
+
+       int (*pcre32_callout)(pcre32_callout_block *);
+
+
+DESCRIPTION
+
+       PCRE provides a feature called "callout", which is a means of temporar-
+       ily passing control to the caller of PCRE  in  the  middle  of  pattern
+       matching.  The  caller of PCRE provides an external function by putting
+       its entry point in the global variable pcre_callout (pcre16_callout for
+       the 16-bit library, pcre32_callout for the 32-bit library). By default,
+       this variable contains NULL, which disables all calling out.
+
+       Within a regular expression, (?C) indicates the  points  at  which  the
+       external  function  is  to  be  called. Different callout points can be
+       identified by putting a number less than 256 after the  letter  C.  The
+       default  value  is  zero.   For  example,  this pattern has two callout
+       points:
+
+         (?C1)abc(?C2)def
+
+       If the PCRE_AUTO_CALLOUT option bit is set when a pattern is  compiled,
+       PCRE  automatically  inserts callouts, all with number 255, before each
+       item in the pattern. For example, if PCRE_AUTO_CALLOUT is used with the
+       pattern
+
+         A(\d{2}|--)
+
+       it is processed as if it were
+
+       (?C255)A(?C255)((?C255)\d{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255)
+
+       Notice  that  there  is a callout before and after each parenthesis and
+       alternation bar. If the pattern contains a conditional group whose con-
+       dition  is  an  assertion, an automatic callout is inserted immediately
+       before the condition. Such a callout may also be  inserted  explicitly,
+       for example:
+
+         (?(?C9)(?=a)ab|de)
+
+       This  applies only to assertion conditions (because they are themselves
+       independent groups).
+
+       Automatic callouts can be used for tracking  the  progress  of  pattern
+       matching.   The pcretest program has a pattern qualifier (/C) that sets
+       automatic callouts; when it is used, the output indicates how the  pat-
+       tern  is  being matched. This is useful information when you are trying
+       to optimize the performance of a particular pattern.
+
+
+MISSING CALLOUTS
+
+       You should be aware that, because of optimizations in the way PCRE com-
+       piles and matches patterns, callouts sometimes do not happen exactly as
+       you might expect.
+
+       At compile time, PCRE "auto-possessifies" repeated items when it  knows
+       that  what follows cannot be part of the repeat. For example, a+[bc] is
+       compiled as if it were a++[bc]. The pcretest output when  this  pattern
+       is  anchored  and  then  applied  with automatic callouts to the string
+       "aaaa" is:
+
+         --->aaaa
+          +0 ^        ^
+          +1 ^        a+
+          +3 ^   ^    [bc]
+         No match
+
+       This indicates that when matching [bc] fails, there is no  backtracking
+       into  a+  and  therefore the callouts that would be taken for the back-
+       tracks do not occur.  You can disable the  auto-possessify  feature  by
+       passing PCRE_NO_AUTO_POSSESS to pcre_compile(), or starting the pattern
+       with (*NO_AUTO_POSSESS). If this is done  in  pcretest  (using  the  /O
+       qualifier), the output changes to this:
+
+         --->aaaa
+          +0 ^        ^
+          +1 ^        a+
+          +3 ^   ^    [bc]
+          +3 ^  ^     [bc]
+          +3 ^ ^      [bc]
+          +3 ^^       [bc]
+         No match
+
+       This time, when matching [bc] fails, the matcher backtracks into a+ and
+       tries again, repeatedly, until a+ itself fails.
+
+       Other optimizations that provide fast "no match"  results  also  affect
+       callouts.  For example, if the pattern is
+
+         ab(?C4)cd
+
+       PCRE knows that any matching string must contain the letter "d". If the
+       subject string is "abyz", the lack of "d" means that  matching  doesn't
+       ever  start,  and  the  callout is never reached. However, with "abyd",
+       though the result is still no match, the callout is obeyed.
+
+       If the pattern is studied, PCRE knows the minimum length of a  matching
+       string,  and will immediately give a "no match" return without actually
+       running a match if the subject is not long enough, or,  for  unanchored
+       patterns, if it has been scanned far enough.
+
+       You  can disable these optimizations by passing the PCRE_NO_START_OPTI-
+       MIZE option to the matching function, or by starting the  pattern  with
+       (*NO_START_OPT).  This slows down the matching process, but does ensure
+       that callouts such as the example above are obeyed.
+
+
+THE CALLOUT INTERFACE
+
+       During matching, when PCRE reaches a callout point, the external  func-
+       tion defined by pcre_callout or pcre[16|32]_callout is called (if it is
+       set). This applies to both normal and DFA matching. The  only  argument
+       to   the   callout   function   is  a  pointer  to  a  pcre_callout  or
+       pcre[16|32]_callout block.  These  structures  contains  the  following
+       fields:
+
+         int           version;
+         int           callout_number;
+         int          *offset_vector;
+         const char   *subject;           (8-bit version)
+         PCRE_SPTR16   subject;           (16-bit version)
+         PCRE_SPTR32   subject;           (32-bit version)
+         int           subject_length;
+         int           start_match;
+         int           current_position;
+         int           capture_top;
+         int           capture_last;
+         void         *callout_data;
+         int           pattern_position;
+         int           next_item_length;
+         const unsigned char *mark;       (8-bit version)
+         const PCRE_UCHAR16  *mark;       (16-bit version)
+         const PCRE_UCHAR32  *mark;       (32-bit version)
+
+       The  version  field  is an integer containing the version number of the
+       block format. The initial version was 0; the current version is 2.  The
+       version  number  will  change  again in future if additional fields are
+       added, but the intention is never to remove any of the existing fields.
+
+       The callout_number field contains the number of the  callout,  as  com-
+       piled  into  the pattern (that is, the number after ?C for manual call-
+       outs, and 255 for automatically generated callouts).
+
+       The offset_vector field is a pointer to the vector of offsets that  was
+       passed  by  the  caller  to  the matching function. When pcre_exec() or
+       pcre[16|32]_exec() is used, the contents can be inspected, in order  to
+       extract  substrings  that  have been matched so far, in the same way as
+       for extracting substrings after a match  has  completed.  For  the  DFA
+       matching functions, this field is not useful.
+
+       The subject and subject_length fields contain copies of the values that
+       were passed to the matching function.
+
+       The start_match field normally contains the offset within  the  subject
+       at  which  the  current  match  attempt started. However, if the escape
+       sequence \K has been encountered, this value is changed to reflect  the
+       modified  starting  point.  If the pattern is not anchored, the callout
+       function may be called several times from the same point in the pattern
+       for different starting points in the subject.
+
+       The  current_position  field  contains the offset within the subject of
+       the current match pointer.
+
+       When the pcre_exec() or pcre[16|32]_exec()  is  used,  the  capture_top
+       field  contains  one  more than the number of the highest numbered cap-
+       tured substring so far. If no substrings have been captured, the  value
+       of  capture_top  is one. This is always the case when the DFA functions
+       are used, because they do not support captured substrings.
+
+       The capture_last field contains the number of the  most  recently  cap-
+       tured  substring. However, when a recursion exits, the value reverts to
+       what it was outside the recursion, as do the  values  of  all  captured
+       substrings.  If  no  substrings  have  been captured, the value of cap-
+       ture_last is -1. This is always the case for  the  DFA  matching  func-
+       tions.
+
+       The  callout_data  field  contains a value that is passed to a matching
+       function specifically so that it can be passed back in callouts. It  is
+       passed  in  the callout_data field of a pcre_extra or pcre[16|32]_extra
+       data structure. If no such data was passed, the value  of  callout_data
+       in  a  callout  block is NULL. There is a description of the pcre_extra
+       structure in the pcreapi documentation.
+
+       The pattern_position field is present from version  1  of  the  callout
+       structure. It contains the offset to the next item to be matched in the
+       pattern string.
+
+       The next_item_length field is present from version  1  of  the  callout
+       structure. It contains the length of the next item to be matched in the
+       pattern string. When the callout immediately  precedes  an  alternation
+       bar,  a  closing  parenthesis, or the end of the pattern, the length is
+       zero. When the callout precedes an opening parenthesis, the  length  is
+       that of the entire subpattern.
+
+       The  pattern_position  and next_item_length fields are intended to help
+       in distinguishing between different automatic callouts, which all  have
+       the same callout number. However, they are set for all callouts.
+
+       The  mark  field is present from version 2 of the callout structure. In
+       callouts from pcre_exec() or pcre[16|32]_exec() it contains  a  pointer
+       to  the  zero-terminated  name  of  the  most  recently passed (*MARK),
+       (*PRUNE), or (*THEN) item in the match, or NULL if no such  items  have
+       been  passed.  Instances  of  (*PRUNE) or (*THEN) without a name do not
+       obliterate a previous (*MARK). In callouts from the DFA matching  func-
+       tions this field always contains NULL.
+
+
+RETURN VALUES
+
+       The  external callout function returns an integer to PCRE. If the value
+       is zero, matching proceeds as normal. If  the  value  is  greater  than
+       zero,  matching  fails  at  the current point, but the testing of other
+       matching possibilities goes ahead, just as if a lookahead assertion had
+       failed.  If  the  value  is less than zero, the match is abandoned, the
+       matching function returns the negative value.
+
+       Negative  values  should  normally  be   chosen   from   the   set   of
+       PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan-
+       dard "no  match"  failure.   The  error  number  PCRE_ERROR_CALLOUT  is
+       reserved  for  use  by callout functions; it will never be used by PCRE
+       itself.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 12 November 2013
+       Copyright (c) 1997-2013 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCRECOMPAT(3)              Library Functions Manual              PCRECOMPAT(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+DIFFERENCES BETWEEN PCRE AND PERL
+
+       This  document describes the differences in the ways that PCRE and Perl
+       handle regular expressions. The differences  described  here  are  with
+       respect to Perl versions 5.10 and above.
+
+       1. PCRE has only a subset of Perl's Unicode support. Details of what it
+       does have are given in the pcreunicode page.
+
+       2. PCRE allows repeat quantifiers only on parenthesized assertions, but
+       they  do  not mean what you might think. For example, (?!a){3} does not
+       assert that the next three characters are not "a". It just asserts that
+       the next character is not "a" three times (in principle: PCRE optimizes
+       this to run the assertion just once). Perl allows repeat quantifiers on
+       other assertions such as \b, but these do not seem to have any use.
+
+       3.  Capturing  subpatterns  that occur inside negative lookahead asser-
+       tions are counted, but their entries in the offsets  vector  are  never
+       set.  Perl sometimes (but not always) sets its numerical variables from
+       inside negative assertions.
+
+       4. Though binary zero characters are supported in the  subject  string,
+       they are not allowed in a pattern string because it is passed as a nor-
+       mal C string, terminated by zero. The escape sequence \0 can be used in
+       the pattern to represent a binary zero.
+
+       5.  The  following Perl escape sequences are not supported: \l, \u, \L,
+       \U, and \N when followed by a character name or Unicode value.  (\N  on
+       its own, matching a non-newline character, is supported.) In fact these
+       are implemented by Perl's general string-handling and are not  part  of
+       its  pattern  matching engine. If any of these are encountered by PCRE,
+       an error is generated by default. However, if the  PCRE_JAVASCRIPT_COM-
+       PAT  option  is set, \U and \u are interpreted as JavaScript interprets
+       them.
+
+       6. The Perl escape sequences \p, \P, and \X are supported only if  PCRE
+       is  built  with Unicode character property support. The properties that
+       can be tested with \p and \P are limited to the general category  prop-
+       erties  such  as  Lu and Nd, script names such as Greek or Han, and the
+       derived properties Any and L&. PCRE does  support  the  Cs  (surrogate)
+       property,  which  Perl  does  not; the Perl documentation says "Because
+       Perl hides the need for the user to understand the internal representa-
+       tion  of Unicode characters, there is no need to implement the somewhat
+       messy concept of surrogates."
+
+       7. PCRE does support the \Q...\E escape for quoting substrings. Charac-
+       ters  in  between  are  treated as literals. This is slightly different
+       from Perl in that $ and @ are  also  handled  as  literals  inside  the
+       quotes.  In Perl, they cause variable interpolation (but of course PCRE
+       does not have variables). Note the following examples:
+
+           Pattern            PCRE matches      Perl matches
+
+           \Qabc$xyz\E        abc$xyz           abc followed by the
+                                                  contents of $xyz
+           \Qabc\$xyz\E       abc\$xyz          abc\$xyz
+           \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
+
+       The \Q...\E sequence is recognized both inside  and  outside  character
+       classes.
+
+       8. Fairly obviously, PCRE does not support the (?{code}) and (??{code})
+       constructions. However, there is support for recursive  patterns.  This
+       is  not  available  in Perl 5.8, but it is in Perl 5.10. Also, the PCRE
+       "callout" feature allows an external function to be called during  pat-
+       tern matching. See the pcrecallout documentation for details.
+
+       9.  Subpatterns  that  are called as subroutines (whether or not recur-
+       sively) are always treated as atomic  groups  in  PCRE.  This  is  like
+       Python,  but  unlike Perl.  Captured values that are set outside a sub-
+       routine call can be reference from inside in PCRE,  but  not  in  Perl.
+       There is a discussion that explains these differences in more detail in
+       the section on recursion differences from Perl in the pcrepattern page.
+
+       10. If any of the backtracking control verbs are used in  a  subpattern
+       that  is  called  as  a  subroutine (whether or not recursively), their
+       effect is confined to that subpattern; it does not extend to  the  sur-
+       rounding  pattern.  This is not always the case in Perl. In particular,
+       if (*THEN) is present in a group that is called as  a  subroutine,  its
+       action is limited to that group, even if the group does not contain any
+       | characters. Note that such subpatterns are processed as  anchored  at
+       the point where they are tested.
+
+       11.  If a pattern contains more than one backtracking control verb, the
+       first one that is backtracked onto acts. For example,  in  the  pattern
+       A(*COMMIT)B(*PRUNE)C  a  failure in B triggers (*COMMIT), but a failure
+       in C triggers (*PRUNE). Perl's behaviour is more complex; in many cases
+       it is the same as PCRE, but there are examples where it differs.
+
+       12.  Most  backtracking  verbs in assertions have their normal actions.
+       They are not confined to the assertion.
+
+       13. There are some differences that are concerned with the settings  of
+       captured  strings  when  part  of  a  pattern is repeated. For example,
+       matching "aba" against the  pattern  /^(a(b)?)+$/  in  Perl  leaves  $2
+       unset, but in PCRE it is set to "b".
+
+       14.  PCRE's handling of duplicate subpattern numbers and duplicate sub-
+       pattern names is not as general as Perl's. This is a consequence of the
+       fact the PCRE works internally just with numbers, using an external ta-
+       ble to translate between numbers and names. In  particular,  a  pattern
+       such  as  (?|(?A)|(?  (Oniguruma  syntax)  are  not synonymous. The former is a back
+       reference; the latter is a subroutine call.
+
+   Generic character types
+
+       Another use of backslash is for specifying generic character types:
+
+         \d     any decimal digit
+         \D     any character that is not a decimal digit
+         \h     any horizontal white space character
+         \H     any character that is not a horizontal white space character
+         \s     any white space character
+         \S     any character that is not a white space character
+         \v     any vertical white space character
+         \V     any character that is not a vertical white space character
+         \w     any "word" character
+         \W     any "non-word" character
+
+       There is also the single sequence \N, which matches a non-newline char-
+       acter.   This  is the same as the "." metacharacter when PCRE_DOTALL is
+       not set. Perl also uses \N to match characters by name; PCRE  does  not
+       support this.
+
+       Each  pair of lower and upper case escape sequences partitions the com-
+       plete set of characters into two disjoint  sets.  Any  given  character
+       matches  one, and only one, of each pair. The sequences can appear both
+       inside and outside character classes. They each match one character  of
+       the  appropriate  type.  If the current matching point is at the end of
+       the subject string, all of them fail, because there is no character  to
+       match.
+
+       For  compatibility with Perl, \s did not used to match the VT character
+       (code 11), which made it different from the the  POSIX  "space"  class.
+       However,  Perl  added  VT  at  release  5.18, and PCRE followed suit at
+       release 8.34. The default \s characters are now HT  (9),  LF  (10),  VT
+       (11),  FF  (12),  CR  (13),  and space (32), which are defined as white
+       space in the "C" locale. This list may vary if locale-specific matching
+       is  taking place. For example, in some locales the "non-breaking space"
+       character (\xA0) is recognized as white space, and  in  others  the  VT
+       character is not.
+
+       A  "word"  character is an underscore or any character that is a letter
+       or digit.  By default, the definition of letters  and  digits  is  con-
+       trolled  by PCRE's low-valued character tables, and may vary if locale-
+       specific matching is taking place (see "Locale support" in the  pcreapi
+       page).  For  example,  in  a French locale such as "fr_FR" in Unix-like
+       systems, or "french" in Windows, some character codes greater than  127
+       are  used  for  accented letters, and these are then matched by \w. The
+       use of locales with Unicode is discouraged.
+
+       By default, characters whose code points are  greater  than  127  never
+       match \d, \s, or \w, and always match \D, \S, and \W, although this may
+       vary for characters in the range 128-255 when locale-specific  matching
+       is  happening.   These  escape sequences retain their original meanings
+       from before Unicode support was available, mainly for  efficiency  rea-
+       sons.  If  PCRE  is  compiled  with  Unicode  property support, and the
+       PCRE_UCP option is set, the behaviour is changed so that Unicode  prop-
+       erties are used to determine character types, as follows:
+
+         \d  any character that matches \p{Nd} (decimal digit)
+         \s  any character that matches \p{Z} or \h or \v
+         \w  any character that matches \p{L} or \p{N}, plus underscore
+
+       The  upper case escapes match the inverse sets of characters. Note that
+       \d matches only decimal digits, whereas \w matches any  Unicode  digit,
+       as  well as any Unicode letter, and underscore. Note also that PCRE_UCP
+       affects \b, and \B because they are defined in  terms  of  \w  and  \W.
+       Matching these sequences is noticeably slower when PCRE_UCP is set.
+
+       The  sequences  \h, \H, \v, and \V are features that were added to Perl
+       at release 5.10. In contrast to the other sequences, which  match  only
+       ASCII  characters  by  default,  these always match certain high-valued
+       code points, whether or not PCRE_UCP is set. The horizontal space char-
+       acters are:
+
+         U+0009     Horizontal tab (HT)
+         U+0020     Space
+         U+00A0     Non-break space
+         U+1680     Ogham space mark
+         U+180E     Mongolian vowel separator
+         U+2000     En quad
+         U+2001     Em quad
+         U+2002     En space
+         U+2003     Em space
+         U+2004     Three-per-em space
+         U+2005     Four-per-em space
+         U+2006     Six-per-em space
+         U+2007     Figure space
+         U+2008     Punctuation space
+         U+2009     Thin space
+         U+200A     Hair space
+         U+202F     Narrow no-break space
+         U+205F     Medium mathematical space
+         U+3000     Ideographic space
+
+       The vertical space characters are:
+
+         U+000A     Linefeed (LF)
+         U+000B     Vertical tab (VT)
+         U+000C     Form feed (FF)
+         U+000D     Carriage return (CR)
+         U+0085     Next line (NEL)
+         U+2028     Line separator
+         U+2029     Paragraph separator
+
+       In 8-bit, non-UTF-8 mode, only the characters with codepoints less than
+       256 are relevant.
+
+   Newline sequences
+
+       Outside a character class, by default, the escape sequence  \R  matches
+       any  Unicode newline sequence. In 8-bit non-UTF-8 mode \R is equivalent
+       to the following:
+
+         (?>\r\n|\n|\x0b|\f|\r|\x85)
+
+       This is an example of an "atomic group", details  of  which  are  given
+       below.  This particular group matches either the two-character sequence
+       CR followed by LF, or  one  of  the  single  characters  LF  (linefeed,
+       U+000A),  VT  (vertical  tab, U+000B), FF (form feed, U+000C), CR (car-
+       riage return, U+000D), or NEL (next line,  U+0085).  The  two-character
+       sequence is treated as a single unit that cannot be split.
+
+       In  other modes, two additional characters whose codepoints are greater
+       than 255 are added: LS (line separator, U+2028) and PS (paragraph sepa-
+       rator,  U+2029).   Unicode character property support is not needed for
+       these characters to be recognized.
+
+       It is possible to restrict \R to match only CR, LF, or CRLF (instead of
+       the  complete  set  of  Unicode  line  endings)  by  setting the option
+       PCRE_BSR_ANYCRLF either at compile time or when the pattern is matched.
+       (BSR is an abbrevation for "backslash R".) This can be made the default
+       when PCRE is built; if this is the case, the  other  behaviour  can  be
+       requested  via  the  PCRE_BSR_UNICODE  option.   It is also possible to
+       specify these settings by starting a pattern string  with  one  of  the
+       following sequences:
+
+         (*BSR_ANYCRLF)   CR, LF, or CRLF only
+         (*BSR_UNICODE)   any Unicode newline sequence
+
+       These override the default and the options given to the compiling func-
+       tion, but they can themselves be  overridden  by  options  given  to  a
+       matching  function.  Note  that  these  special settings, which are not
+       Perl-compatible, are recognized only at the very start  of  a  pattern,
+       and  that  they  must  be  in  upper  case. If more than one of them is
+       present, the last one is used. They can be combined with  a  change  of
+       newline convention; for example, a pattern can start with:
+
+         (*ANY)(*BSR_ANYCRLF)
+
+       They  can also be combined with the (*UTF8), (*UTF16), (*UTF32), (*UTF)
+       or (*UCP) special sequences. Inside a character class, \R is treated as
+       an  unrecognized  escape  sequence,  and  so  matches the letter "R" by
+       default, but causes an error if PCRE_EXTRA is set.
+
+   Unicode character properties
+
+       When PCRE is built with Unicode character property support, three addi-
+       tional  escape sequences that match characters with specific properties
+       are available.  When in 8-bit non-UTF-8 mode, these  sequences  are  of
+       course  limited  to  testing  characters whose codepoints are less than
+       256, but they do work in this mode.  The extra escape sequences are:
+
+         \p{xx}   a character with the xx property
+         \P{xx}   a character without the xx property
+         \X       a Unicode extended grapheme cluster
+
+       The property names represented by xx above are limited to  the  Unicode
+       script names, the general category properties, "Any", which matches any
+       character  (including  newline),  and  some  special  PCRE   properties
+       (described  in the next section).  Other Perl properties such as "InMu-
+       sicalSymbols" are not currently supported by PCRE.  Note  that  \P{Any}
+       does not match any characters, so always causes a match failure.
+
+       Sets of Unicode characters are defined as belonging to certain scripts.
+       A character from one of these sets can be matched using a script  name.
+       For example:
+
+         \p{Greek}
+         \P{Han}
+
+       Those  that are not part of an identified script are lumped together as
+       "Common". The current list of scripts is:
+
+       Arabic, Armenian, Avestan, Balinese, Bamum, Batak,  Bengali,  Bopomofo,
+       Brahmi,  Braille, Buginese, Buhid, Canadian_Aboriginal, Carian, Chakma,
+       Cham, Cherokee, Common, Coptic, Cuneiform, Cypriot, Cyrillic,  Deseret,
+       Devanagari,   Egyptian_Hieroglyphs,   Ethiopic,  Georgian,  Glagolitic,
+       Gothic, Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew,  Hira-
+       gana,   Imperial_Aramaic,  Inherited,  Inscriptional_Pahlavi,  Inscrip-
+       tional_Parthian,  Javanese,  Kaithi,   Kannada,   Katakana,   Kayah_Li,
+       Kharoshthi,  Khmer,  Lao, Latin, Lepcha, Limbu, Linear_B, Lisu, Lycian,
+       Lydian,    Malayalam,    Mandaic,    Meetei_Mayek,    Meroitic_Cursive,
+       Meroitic_Hieroglyphs,   Miao,  Mongolian,  Myanmar,  New_Tai_Lue,  Nko,
+       Ogham,   Old_Italic,   Old_Persian,   Old_South_Arabian,    Old_Turkic,
+       Ol_Chiki,  Oriya, Osmanya, Phags_Pa, Phoenician, Rejang, Runic, Samari-
+       tan, Saurashtra, Sharada, Shavian,  Sinhala,  Sora_Sompeng,  Sundanese,
+       Syloti_Nagri,  Syriac,  Tagalog,  Tagbanwa, Tai_Le, Tai_Tham, Tai_Viet,
+       Takri, Tamil, Telugu, Thaana, Thai, Tibetan, Tifinagh,  Ugaritic,  Vai,
+       Yi.
+
+       Each character has exactly one Unicode general category property, spec-
+       ified by a two-letter abbreviation. For compatibility with Perl,  nega-
+       tion  can  be  specified  by including a circumflex between the opening
+       brace and the property name.  For  example,  \p{^Lu}  is  the  same  as
+       \P{Lu}.
+
+       If only one letter is specified with \p or \P, it includes all the gen-
+       eral category properties that start with that letter. In this case,  in
+       the  absence of negation, the curly brackets in the escape sequence are
+       optional; these two examples have the same effect:
+
+         \p{L}
+         \pL
+
+       The following general category property codes are supported:
+
+         C     Other
+         Cc    Control
+         Cf    Format
+         Cn    Unassigned
+         Co    Private use
+         Cs    Surrogate
+
+         L     Letter
+         Ll    Lower case letter
+         Lm    Modifier letter
+         Lo    Other letter
+         Lt    Title case letter
+         Lu    Upper case letter
+
+         M     Mark
+         Mc    Spacing mark
+         Me    Enclosing mark
+         Mn    Non-spacing mark
+
+         N     Number
+         Nd    Decimal number
+         Nl    Letter number
+         No    Other number
+
+         P     Punctuation
+         Pc    Connector punctuation
+         Pd    Dash punctuation
+         Pe    Close punctuation
+         Pf    Final punctuation
+         Pi    Initial punctuation
+         Po    Other punctuation
+         Ps    Open punctuation
+
+         S     Symbol
+         Sc    Currency symbol
+         Sk    Modifier symbol
+         Sm    Mathematical symbol
+         So    Other symbol
+
+         Z     Separator
+         Zl    Line separator
+         Zp    Paragraph separator
+         Zs    Space separator
+
+       The special property L& is also supported: it matches a character  that
+       has  the  Lu,  Ll, or Lt property, in other words, a letter that is not
+       classified as a modifier or "other".
+
+       The Cs (Surrogate) property applies only to  characters  in  the  range
+       U+D800  to U+DFFF. Such characters are not valid in Unicode strings and
+       so cannot be tested by PCRE, unless  UTF  validity  checking  has  been
+       turned    off    (see    the    discussion    of    PCRE_NO_UTF8_CHECK,
+       PCRE_NO_UTF16_CHECK and PCRE_NO_UTF32_CHECK in the pcreapi page).  Perl
+       does not support the Cs property.
+
+       The  long  synonyms  for  property  names  that  Perl supports (such as
+       \p{Letter}) are not supported by PCRE, nor is it  permitted  to  prefix
+       any of these properties with "Is".
+
+       No character that is in the Unicode table has the Cn (unassigned) prop-
+       erty.  Instead, this property is assumed for any code point that is not
+       in the Unicode table.
+
+       Specifying  caseless  matching  does not affect these escape sequences.
+       For example, \p{Lu} always matches only upper  case  letters.  This  is
+       different from the behaviour of current versions of Perl.
+
+       Matching  characters  by Unicode property is not fast, because PCRE has
+       to do a multistage table lookup in order to find  a  character's  prop-
+       erty. That is why the traditional escape sequences such as \d and \w do
+       not use Unicode properties in PCRE by default, though you can make them
+       do  so  by  setting the PCRE_UCP option or by starting the pattern with
+       (*UCP).
+
+   Extended grapheme clusters
+
+       The \X escape matches any number of Unicode  characters  that  form  an
+       "extended grapheme cluster", and treats the sequence as an atomic group
+       (see below).  Up to and including release 8.31, PCRE  matched  an  ear-
+       lier, simpler definition that was equivalent to
+
+         (?>\PM\pM*)
+
+       That  is,  it matched a character without the "mark" property, followed
+       by zero or more characters with the "mark"  property.  Characters  with
+       the  "mark"  property are typically non-spacing accents that affect the
+       preceding character.
+
+       This simple definition was extended in Unicode to include more  compli-
+       cated  kinds of composite character by giving each character a grapheme
+       breaking property, and creating rules  that  use  these  properties  to
+       define  the  boundaries  of  extended grapheme clusters. In releases of
+       PCRE later than 8.31, \X matches one of these clusters.
+
+       \X always matches at least one character. Then it  decides  whether  to
+       add additional characters according to the following rules for ending a
+       cluster:
+
+       1. End at the end of the subject string.
+
+       2. Do not end between CR and LF; otherwise end after any control  char-
+       acter.
+
+       3.  Do  not  break  Hangul (a Korean script) syllable sequences. Hangul
+       characters are of five types: L, V, T, LV, and LVT. An L character  may
+       be  followed by an L, V, LV, or LVT character; an LV or V character may
+       be followed by a V or T character; an LVT or T character may be follwed
+       only by a T character.
+
+       4.  Do not end before extending characters or spacing marks. Characters
+       with the "mark" property always have  the  "extend"  grapheme  breaking
+       property.
+
+       5. Do not end after prepend characters.
+
+       6. Otherwise, end the cluster.
+
+   PCRE's additional properties
+
+       As  well  as the standard Unicode properties described above, PCRE sup-
+       ports four more that make it possible  to  convert  traditional  escape
+       sequences  such as \w and \s to use Unicode properties. PCRE uses these
+       non-standard, non-Perl properties internally when PCRE_UCP is set. How-
+       ever, they may also be used explicitly. These properties are:
+
+         Xan   Any alphanumeric character
+         Xps   Any POSIX space character
+         Xsp   Any Perl space character
+         Xwd   Any Perl "word" character
+
+       Xan  matches  characters that have either the L (letter) or the N (num-
+       ber) property. Xps matches the characters tab, linefeed, vertical  tab,
+       form  feed,  or carriage return, and any other character that has the Z
+       (separator) property.  Xsp is the same as Xps; it used to exclude  ver-
+       tical  tab,  for Perl compatibility, but Perl changed, and so PCRE fol-
+       lowed at release 8.34. Xwd matches the same  characters  as  Xan,  plus
+       underscore.
+
+       There  is another non-standard property, Xuc, which matches any charac-
+       ter that can be represented by a Universal Character Name  in  C++  and
+       other  programming  languages.  These are the characters $, @, ` (grave
+       accent), and all characters with Unicode code points  greater  than  or
+       equal  to U+00A0, except for the surrogates U+D800 to U+DFFF. Note that
+       most base (ASCII) characters are excluded. (Universal  Character  Names
+       are  of  the  form \uHHHH or \UHHHHHHHH where H is a hexadecimal digit.
+       Note that the Xuc property does not match these sequences but the char-
+       acters that they represent.)
+
+   Resetting the match start
+
+       The  escape sequence \K causes any previously matched characters not to
+       be included in the final matched sequence. For example, the pattern:
+
+         foo\Kbar
+
+       matches "foobar", but reports that it has matched "bar".  This  feature
+       is  similar  to  a lookbehind assertion (described below).  However, in
+       this case, the part of the subject before the real match does not  have
+       to  be of fixed length, as lookbehind assertions do. The use of \K does
+       not interfere with the setting of captured  substrings.   For  example,
+       when the pattern
+
+         (foo)\Kbar
+
+       matches "foobar", the first substring is still set to "foo".
+
+       Perl  documents  that  the  use  of  \K  within assertions is "not well
+       defined". In PCRE, \K is acted upon  when  it  occurs  inside  positive
+       assertions,  but  is  ignored  in negative assertions. Note that when a
+       pattern such as (?=ab\K) matches, the reported start of the  match  can
+       be greater than the end of the match.
+
+   Simple assertions
+
+       The  final use of backslash is for certain simple assertions. An asser-
+       tion specifies a condition that has to be met at a particular point  in
+       a  match, without consuming any characters from the subject string. The
+       use of subpatterns for more complicated assertions is described  below.
+       The backslashed assertions are:
+
+         \b     matches at a word boundary
+         \B     matches when not at a word boundary
+         \A     matches at the start of the subject
+         \Z     matches at the end of the subject
+                 also matches before a newline at the end of the subject
+         \z     matches only at the end of the subject
+         \G     matches at the first matching position in the subject
+
+       Inside  a  character  class, \b has a different meaning; it matches the
+       backspace character. If any other of  these  assertions  appears  in  a
+       character  class, by default it matches the corresponding literal char-
+       acter  (for  example,  \B  matches  the  letter  B).  However,  if  the
+       PCRE_EXTRA  option is set, an "invalid escape sequence" error is gener-
+       ated instead.
+
+       A word boundary is a position in the subject string where  the  current
+       character  and  the previous character do not both match \w or \W (i.e.
+       one matches \w and the other matches \W), or the start or  end  of  the
+       string  if  the  first or last character matches \w, respectively. In a
+       UTF mode, the meanings of \w and \W  can  be  changed  by  setting  the
+       PCRE_UCP  option. When this is done, it also affects \b and \B. Neither
+       PCRE nor Perl has a separate "start of word" or "end of  word"  metase-
+       quence.  However,  whatever follows \b normally determines which it is.
+       For example, the fragment \ba matches "a" at the start of a word.
+
+       The \A, \Z, and \z assertions differ from  the  traditional  circumflex
+       and dollar (described in the next section) in that they only ever match
+       at the very start and end of the subject string, whatever  options  are
+       set.  Thus,  they are independent of multiline mode. These three asser-
+       tions are not affected by the PCRE_NOTBOL or PCRE_NOTEOL options, which
+       affect  only the behaviour of the circumflex and dollar metacharacters.
+       However, if the startoffset argument of pcre_exec() is non-zero,  indi-
+       cating that matching is to start at a point other than the beginning of
+       the subject, \A can never match. The difference between \Z  and  \z  is
+       that \Z matches before a newline at the end of the string as well as at
+       the very end, whereas \z matches only at the end.
+
+       The \G assertion is true only when the current matching position is  at
+       the  start point of the match, as specified by the startoffset argument
+       of pcre_exec(). It differs from \A when the  value  of  startoffset  is
+       non-zero.  By calling pcre_exec() multiple times with appropriate argu-
+       ments, you can mimic Perl's /g option, and it is in this kind of imple-
+       mentation where \G can be useful.
+
+       Note,  however,  that  PCRE's interpretation of \G, as the start of the
+       current match, is subtly different from Perl's, which defines it as the
+       end  of  the  previous  match. In Perl, these can be different when the
+       previously matched string was empty. Because PCRE does just  one  match
+       at a time, it cannot reproduce this behaviour.
+
+       If  all  the alternatives of a pattern begin with \G, the expression is
+       anchored to the starting match position, and the "anchored" flag is set
+       in the compiled regular expression.
+
+
+CIRCUMFLEX AND DOLLAR
+
+       The  circumflex  and  dollar  metacharacters are zero-width assertions.
+       That is, they test for a particular condition being true  without  con-
+       suming any characters from the subject string.
+
+       Outside a character class, in the default matching mode, the circumflex
+       character is an assertion that is true only  if  the  current  matching
+       point  is  at the start of the subject string. If the startoffset argu-
+       ment of pcre_exec() is non-zero, circumflex  can  never  match  if  the
+       PCRE_MULTILINE  option  is  unset. Inside a character class, circumflex
+       has an entirely different meaning (see below).
+
+       Circumflex need not be the first character of the pattern if  a  number
+       of  alternatives are involved, but it should be the first thing in each
+       alternative in which it appears if the pattern is ever  to  match  that
+       branch.  If all possible alternatives start with a circumflex, that is,
+       if the pattern is constrained to match only at the start  of  the  sub-
+       ject,  it  is  said  to be an "anchored" pattern. (There are also other
+       constructs that can cause a pattern to be anchored.)
+
+       The dollar character is an assertion that is true only if  the  current
+       matching  point  is  at  the  end of the subject string, or immediately
+       before a newline at the end of the string (by default). Note,  however,
+       that  it  does  not  actually match the newline. Dollar need not be the
+       last character of the pattern if a number of alternatives are involved,
+       but  it should be the last item in any branch in which it appears. Dol-
+       lar has no special meaning in a character class.
+
+       The meaning of dollar can be changed so that it  matches  only  at  the
+       very  end  of  the string, by setting the PCRE_DOLLAR_ENDONLY option at
+       compile time. This does not affect the \Z assertion.
+
+       The meanings of the circumflex and dollar characters are changed if the
+       PCRE_MULTILINE  option  is  set.  When  this  is the case, a circumflex
+       matches immediately after internal newlines as well as at the start  of
+       the  subject  string.  It  does not match after a newline that ends the
+       string. A dollar matches before any newlines in the string, as well  as
+       at  the very end, when PCRE_MULTILINE is set. When newline is specified
+       as the two-character sequence CRLF, isolated CR and  LF  characters  do
+       not indicate newlines.
+
+       For  example, the pattern /^abc$/ matches the subject string "def\nabc"
+       (where \n represents a newline) in multiline mode, but  not  otherwise.
+       Consequently,  patterns  that  are anchored in single line mode because
+       all branches start with ^ are not anchored in  multiline  mode,  and  a
+       match  for  circumflex  is  possible  when  the startoffset argument of
+       pcre_exec() is non-zero. The PCRE_DOLLAR_ENDONLY option is  ignored  if
+       PCRE_MULTILINE is set.
+
+       Note  that  the sequences \A, \Z, and \z can be used to match the start
+       and end of the subject in both modes, and if all branches of a  pattern
+       start  with  \A it is always anchored, whether or not PCRE_MULTILINE is
+       set.
+
+
+FULL STOP (PERIOD, DOT) AND \N
+
+       Outside a character class, a dot in the pattern matches any one charac-
+       ter  in  the subject string except (by default) a character that signi-
+       fies the end of a line.
+
+       When a line ending is defined as a single character, dot never  matches
+       that  character; when the two-character sequence CRLF is used, dot does
+       not match CR if it is immediately followed  by  LF,  but  otherwise  it
+       matches  all characters (including isolated CRs and LFs). When any Uni-
+       code line endings are being recognized, dot does not match CR or LF  or
+       any of the other line ending characters.
+
+       The  behaviour  of  dot  with regard to newlines can be changed. If the
+       PCRE_DOTALL option is set, a dot matches  any  one  character,  without
+       exception. If the two-character sequence CRLF is present in the subject
+       string, it takes two dots to match it.
+
+       The handling of dot is entirely independent of the handling of  circum-
+       flex  and  dollar,  the  only relationship being that they both involve
+       newlines. Dot has no special meaning in a character class.
+
+       The escape sequence \N behaves like  a  dot,  except  that  it  is  not
+       affected  by  the  PCRE_DOTALL  option.  In other words, it matches any
+       character except one that signifies the end of a line. Perl  also  uses
+       \N to match characters by name; PCRE does not support this.
+
+
+MATCHING A SINGLE DATA UNIT
+
+       Outside  a character class, the escape sequence \C matches any one data
+       unit, whether or not a UTF mode is set. In the 8-bit library, one  data
+       unit  is  one  byte;  in the 16-bit library it is a 16-bit unit; in the
+       32-bit library it is a 32-bit unit. Unlike a  dot,  \C  always  matches
+       line-ending  characters.  The  feature  is provided in Perl in order to
+       match individual bytes in UTF-8 mode, but it is unclear how it can use-
+       fully  be  used.  Because  \C breaks up characters into individual data
+       units, matching one unit with \C in a UTF mode means that the  rest  of
+       the string may start with a malformed UTF character. This has undefined
+       results, because PCRE assumes that it is dealing with valid UTF strings
+       (and  by  default  it checks this at the start of processing unless the
+       PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK or  PCRE_NO_UTF32_CHECK  option
+       is used).
+
+       PCRE  does  not  allow \C to appear in lookbehind assertions (described
+       below) in a UTF mode, because this would make it impossible  to  calcu-
+       late the length of the lookbehind.
+
+       In general, the \C escape sequence is best avoided. However, one way of
+       using it that avoids the problem of malformed UTF characters is to  use
+       a  lookahead to check the length of the next character, as in this pat-
+       tern, which could be used with a UTF-8 string (ignore white  space  and
+       line breaks):
+
+         (?| (?=[\x00-\x7f])(\C) |
+             (?=[\x80-\x{7ff}])(\C)(\C) |
+             (?=[\x{800}-\x{ffff}])(\C)(\C)(\C) |
+             (?=[\x{10000}-\x{1fffff}])(\C)(\C)(\C)(\C))
+
+       A  group  that starts with (?| resets the capturing parentheses numbers
+       in each alternative (see "Duplicate  Subpattern  Numbers"  below).  The
+       assertions  at  the start of each branch check the next UTF-8 character
+       for values whose encoding uses 1, 2, 3, or 4 bytes,  respectively.  The
+       character's  individual bytes are then captured by the appropriate num-
+       ber of groups.
+
+
+SQUARE BRACKETS AND CHARACTER CLASSES
+
+       An opening square bracket introduces a character class, terminated by a
+       closing square bracket. A closing square bracket on its own is not spe-
+       cial by default.  However, if the PCRE_JAVASCRIPT_COMPAT option is set,
+       a lone closing square bracket causes a compile-time error. If a closing
+       square bracket is required as a member of the class, it should  be  the
+       first  data  character  in  the  class (after an initial circumflex, if
+       present) or escaped with a backslash.
+
+       A character class matches a single character in the subject. In  a  UTF
+       mode,  the  character  may  be  more than one data unit long. A matched
+       character must be in the set of characters defined by the class, unless
+       the  first  character in the class definition is a circumflex, in which
+       case the subject character must not be in the set defined by the class.
+       If  a  circumflex is actually required as a member of the class, ensure
+       it is not the first character, or escape it with a backslash.
+
+       For example, the character class [aeiou] matches any lower case  vowel,
+       while  [^aeiou]  matches  any character that is not a lower case vowel.
+       Note that a circumflex is just a convenient notation for specifying the
+       characters  that  are in the class by enumerating those that are not. A
+       class that starts with a circumflex is not an assertion; it still  con-
+       sumes  a  character  from the subject string, and therefore it fails if
+       the current pointer is at the end of the string.
+
+       In UTF-8 (UTF-16, UTF-32) mode, characters with values greater than 255
+       (0xffff)  can be included in a class as a literal string of data units,
+       or by using the \x{ escaping mechanism.
+
+       When caseless matching is set, any letters in a  class  represent  both
+       their  upper  case  and lower case versions, so for example, a caseless
+       [aeiou] matches "A" as well as "a", and a caseless  [^aeiou]  does  not
+       match  "A", whereas a caseful version would. In a UTF mode, PCRE always
+       understands the concept of case for characters whose  values  are  less
+       than  128, so caseless matching is always possible. For characters with
+       higher values, the concept of case is supported  if  PCRE  is  compiled
+       with  Unicode  property support, but not otherwise.  If you want to use
+       caseless matching in a UTF mode for characters 128 and above, you  must
+       ensure  that  PCRE is compiled with Unicode property support as well as
+       with UTF support.
+
+       Characters that might indicate line breaks are  never  treated  in  any
+       special  way  when  matching  character  classes,  whatever line-ending
+       sequence is in  use,  and  whatever  setting  of  the  PCRE_DOTALL  and
+       PCRE_MULTILINE options is used. A class such as [^a] always matches one
+       of these characters.
+
+       The minus (hyphen) character can be used to specify a range of  charac-
+       ters  in  a  character  class.  For  example,  [d-m] matches any letter
+       between d and m, inclusive. If a  minus  character  is  required  in  a
+       class,  it  must  be  escaped  with a backslash or appear in a position
+       where it cannot be interpreted as indicating a range, typically as  the
+       first or last character in the class, or immediately after a range. For
+       example, [b-d-z] matches letters in the range b to d, a hyphen  charac-
+       ter, or z.
+
+       It is not possible to have the literal character "]" as the end charac-
+       ter of a range. A pattern such as [W-]46] is interpreted as a class  of
+       two  characters ("W" and "-") followed by a literal string "46]", so it
+       would match "W46]" or "-46]". However, if the "]"  is  escaped  with  a
+       backslash  it is interpreted as the end of range, so [W-\]46] is inter-
+       preted as a class containing a range followed by two other  characters.
+       The  octal or hexadecimal representation of "]" can also be used to end
+       a range.
+
+       An error is generated if a POSIX character  class  (see  below)  or  an
+       escape  sequence other than one that defines a single character appears
+       at a point where a range ending character  is  expected.  For  example,
+       [z-\xff] is valid, but [A-\d] and [A-[:digit:]] are not.
+
+       Ranges  operate in the collating sequence of character values. They can
+       also  be  used  for  characters  specified  numerically,  for   example
+       [\000-\037].  Ranges  can include any characters that are valid for the
+       current mode.
+
+       If a range that includes letters is used when caseless matching is set,
+       it matches the letters in either case. For example, [W-c] is equivalent
+       to [][\\^_`wxyzabc], matched caselessly, and  in  a  non-UTF  mode,  if
+       character  tables  for  a French locale are in use, [\xc8-\xcb] matches
+       accented E characters in both cases. In UTF modes,  PCRE  supports  the
+       concept  of  case for characters with values greater than 128 only when
+       it is compiled with Unicode property support.
+
+       The character escape sequences \d, \D, \h, \H, \p, \P, \s, \S, \v,  \V,
+       \w, and \W may appear in a character class, and add the characters that
+       they match to the class. For example, [\dABCDEF] matches any  hexadeci-
+       mal  digit.  In  UTF modes, the PCRE_UCP option affects the meanings of
+       \d, \s, \w and their upper case partners, just as  it  does  when  they
+       appear  outside a character class, as described in the section entitled
+       "Generic character types" above. The escape sequence \b has a different
+       meaning  inside  a character class; it matches the backspace character.
+       The sequences \B, \N, \R, and \X are not  special  inside  a  character
+       class.  Like  any other unrecognized escape sequences, they are treated
+       as the literal characters "B", "N", "R", and "X" by default, but  cause
+       an error if the PCRE_EXTRA option is set.
+
+       A  circumflex  can  conveniently  be used with the upper case character
+       types to specify a more restricted set of characters than the  matching
+       lower  case  type.  For example, the class [^\W_] matches any letter or
+       digit, but not underscore, whereas [\w] includes underscore. A positive
+       character class should be read as "something OR something OR ..." and a
+       negative class as "NOT something AND NOT something AND NOT ...".
+
+       The only metacharacters that are recognized in  character  classes  are
+       backslash,  hyphen  (only  where  it can be interpreted as specifying a
+       range), circumflex (only at the start), opening  square  bracket  (only
+       when  it can be interpreted as introducing a POSIX class name, or for a
+       special compatibility feature - see the next  two  sections),  and  the
+       terminating  closing  square  bracket.  However,  escaping  other  non-
+       alphanumeric characters does no harm.
+
+
+POSIX CHARACTER CLASSES
+
+       Perl supports the POSIX notation for character classes. This uses names
+       enclosed  by  [: and :] within the enclosing square brackets. PCRE also
+       supports this notation. For example,
+
+         [01[:alpha:]%]
+
+       matches "0", "1", any alphabetic character, or "%". The supported class
+       names are:
+
+         alnum    letters and digits
+         alpha    letters
+         ascii    character codes 0 - 127
+         blank    space or tab only
+         cntrl    control characters
+         digit    decimal digits (same as \d)
+         graph    printing characters, excluding space
+         lower    lower case letters
+         print    printing characters, including space
+         punct    printing characters, excluding letters and digits and space
+         space    white space (the same as \s from PCRE 8.34)
+         upper    upper case letters
+         word     "word" characters (same as \w)
+         xdigit   hexadecimal digits
+
+       The  default  "space" characters are HT (9), LF (10), VT (11), FF (12),
+       CR (13), and space (32). If locale-specific matching is  taking  place,
+       the  list  of  space characters may be different; there may be fewer or
+       more of them. "Space" used to be different to \s, which did not include
+       VT, for Perl compatibility.  However, Perl changed at release 5.18, and
+       PCRE followed at release 8.34.  "Space" and \s now match the  same  set
+       of characters.
+
+       The  name  "word"  is  a Perl extension, and "blank" is a GNU extension
+       from Perl 5.8. Another Perl extension is negation, which  is  indicated
+       by a ^ character after the colon. For example,
+
+         [12[:^digit:]]
+
+       matches  "1", "2", or any non-digit. PCRE (and Perl) also recognize the
+       POSIX syntax [.ch.] and [=ch=] where "ch" is a "collating element", but
+       these are not supported, and an error is given if they are encountered.
+
+       By default, characters with values greater than 128 do not match any of
+       the POSIX character classes. However, if the PCRE_UCP option is  passed
+       to  pcre_compile(),  some  of  the  classes are changed so that Unicode
+       character properties are used. This is achieved  by  replacing  certain
+       POSIX classes by other sequences, as follows:
+
+         [:alnum:]  becomes  \p{Xan}
+         [:alpha:]  becomes  \p{L}
+         [:blank:]  becomes  \h
+         [:digit:]  becomes  \p{Nd}
+         [:lower:]  becomes  \p{Ll}
+         [:space:]  becomes  \p{Xps}
+         [:upper:]  becomes  \p{Lu}
+         [:word:]   becomes  \p{Xwd}
+
+       Negated  versions, such as [:^alpha:] use \P instead of \p. Three other
+       POSIX classes are handled specially in UCP mode:
+
+       [:graph:] This matches characters that have glyphs that mark  the  page
+                 when printed. In Unicode property terms, it matches all char-
+                 acters with the L, M, N, P, S, or Cf properties, except for:
+
+                   U+061C           Arabic Letter Mark
+                   U+180E           Mongolian Vowel Separator
+                   U+2066 - U+2069  Various "isolate"s
+
+
+       [:print:] This matches the same  characters  as  [:graph:]  plus  space
+                 characters  that  are  not controls, that is, characters with
+                 the Zs property.
+
+       [:punct:] This matches all characters that have the Unicode P (punctua-
+                 tion)  property,  plus those characters whose code points are
+                 less than 128 that have the S (Symbol) property.
+
+       The other POSIX classes are unchanged, and match only  characters  with
+       code points less than 128.
+
+
+COMPATIBILITY FEATURE FOR WORD BOUNDARIES
+
+       In  the POSIX.2 compliant library that was included in 4.4BSD Unix, the
+       ugly syntax [[:<:]] and [[:>:]] is used for matching  "start  of  word"
+       and "end of word". PCRE treats these items as follows:
+
+         [[:<:]]  is converted to  \b(?=\w)
+         [[:>:]]  is converted to  \b(?<=\w)
+
+       Only these exact character sequences are recognized. A sequence such as
+       [a[:<:]b] provokes error for an unrecognized  POSIX  class  name.  This
+       support  is not compatible with Perl. It is provided to help migrations
+       from other environments, and is best not used in any new patterns. Note
+       that  \b matches at the start and the end of a word (see "Simple asser-
+       tions" above), and in a Perl-style pattern the preceding  or  following
+       character  normally  shows  which  is  wanted, without the need for the
+       assertions that are used above in order to give exactly the  POSIX  be-
+       haviour.
+
+
+VERTICAL BAR
+
+       Vertical  bar characters are used to separate alternative patterns. For
+       example, the pattern
+
+         gilbert|sullivan
+
+       matches either "gilbert" or "sullivan". Any number of alternatives  may
+       appear,  and  an  empty  alternative  is  permitted (matching the empty
+       string). The matching process tries each alternative in turn, from left
+       to  right, and the first one that succeeds is used. If the alternatives
+       are within a subpattern (defined below), "succeeds" means matching  the
+       rest of the main pattern as well as the alternative in the subpattern.
+
+
+INTERNAL OPTION SETTING
+
+       The  settings  of  the  PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and
+       PCRE_EXTENDED options (which are Perl-compatible) can be  changed  from
+       within  the  pattern  by  a  sequence  of  Perl option letters enclosed
+       between "(?" and ")".  The option letters are
+
+         i  for PCRE_CASELESS
+         m  for PCRE_MULTILINE
+         s  for PCRE_DOTALL
+         x  for PCRE_EXTENDED
+
+       For example, (?im) sets caseless, multiline matching. It is also possi-
+       ble to unset these options by preceding the letter with a hyphen, and a
+       combined setting and unsetting such as (?im-sx), which sets  PCRE_CASE-
+       LESS  and PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED,
+       is also permitted. If a  letter  appears  both  before  and  after  the
+       hyphen, the option is unset.
+
+       The  PCRE-specific options PCRE_DUPNAMES, PCRE_UNGREEDY, and PCRE_EXTRA
+       can be changed in the same way as the Perl-compatible options by  using
+       the characters J, U and X respectively.
+
+       When  one  of  these  option  changes occurs at top level (that is, not
+       inside subpattern parentheses), the change applies to the remainder  of
+       the pattern that follows. If the change is placed right at the start of
+       a pattern, PCRE extracts it into the global options (and it will there-
+       fore show up in data extracted by the pcre_fullinfo() function).
+
+       An  option  change  within a subpattern (see below for a description of
+       subpatterns) affects only that part of the subpattern that follows  it,
+       so
+
+         (a(?i)b)c
+
+       matches abc and aBc and no other strings (assuming PCRE_CASELESS is not
+       used).  By this means, options can be made to have  different  settings
+       in  different parts of the pattern. Any changes made in one alternative
+       do carry on into subsequent branches within the  same  subpattern.  For
+       example,
+
+         (a(?i)b|c)
+
+       matches  "ab",  "aB",  "c",  and "C", even though when matching "C" the
+       first branch is abandoned before the option setting.  This  is  because
+       the  effects  of option settings happen at compile time. There would be
+       some very weird behaviour otherwise.
+
+       Note: There are other PCRE-specific options that  can  be  set  by  the
+       application  when  the  compiling  or matching functions are called. In
+       some cases the pattern can contain special leading  sequences  such  as
+       (*CRLF)  to  override  what  the  application  has set or what has been
+       defaulted.  Details  are  given  in  the  section   entitled   "Newline
+       sequences"  above.  There  are also the (*UTF8), (*UTF16),(*UTF32), and
+       (*UCP) leading sequences that can be used to set UTF and Unicode  prop-
+       erty  modes;  they are equivalent to setting the PCRE_UTF8, PCRE_UTF16,
+       PCRE_UTF32 and the PCRE_UCP options, respectively. The (*UTF)  sequence
+       is  a  generic version that can be used with any of the libraries. How-
+       ever, the application can set the PCRE_NEVER_UTF  option,  which  locks
+       out the use of the (*UTF) sequences.
+
+
+SUBPATTERNS
+
+       Subpatterns are delimited by parentheses (round brackets), which can be
+       nested.  Turning part of a pattern into a subpattern does two things:
+
+       1. It localizes a set of alternatives. For example, the pattern
+
+         cat(aract|erpillar|)
+
+       matches "cataract", "caterpillar", or "cat". Without  the  parentheses,
+       it would match "cataract", "erpillar" or an empty string.
+
+       2.  It  sets  up  the  subpattern as a capturing subpattern. This means
+       that, when the whole pattern  matches,  that  portion  of  the  subject
+       string that matched the subpattern is passed back to the caller via the
+       ovector argument of the matching function. (This applies  only  to  the
+       traditional  matching functions; the DFA matching functions do not sup-
+       port capturing.)
+
+       Opening parentheses are counted from left to right (starting from 1) to
+       obtain  numbers  for  the  capturing  subpatterns.  For example, if the
+       string "the red king" is matched against the pattern
+
+         the ((red|white) (king|queen))
+
+       the captured substrings are "red king", "red", and "king", and are num-
+       bered 1, 2, and 3, respectively.
+
+       The  fact  that  plain  parentheses  fulfil two functions is not always
+       helpful.  There are often times when a grouping subpattern is  required
+       without  a capturing requirement. If an opening parenthesis is followed
+       by a question mark and a colon, the subpattern does not do any  captur-
+       ing,  and  is  not  counted when computing the number of any subsequent
+       capturing subpatterns. For example, if the string "the white queen"  is
+       matched against the pattern
+
+         the ((?:red|white) (king|queen))
+
+       the captured substrings are "white queen" and "queen", and are numbered
+       1 and 2. The maximum number of capturing subpatterns is 65535.
+
+       As a convenient shorthand, if any option settings are required  at  the
+       start  of  a  non-capturing  subpattern,  the option letters may appear
+       between the "?" and the ":". Thus the two patterns
+
+         (?i:saturday|sunday)
+         (?:(?i)saturday|sunday)
+
+       match exactly the same set of strings. Because alternative branches are
+       tried  from  left  to right, and options are not reset until the end of
+       the subpattern is reached, an option setting in one branch does  affect
+       subsequent  branches,  so  the above patterns match "SUNDAY" as well as
+       "Saturday".
+
+
+DUPLICATE SUBPATTERN NUMBERS
+
+       Perl 5.10 introduced a feature whereby each alternative in a subpattern
+       uses  the same numbers for its capturing parentheses. Such a subpattern
+       starts with (?| and is itself a non-capturing subpattern. For  example,
+       consider this pattern:
+
+         (?|(Sat)ur|(Sun))day
+
+       Because  the two alternatives are inside a (?| group, both sets of cap-
+       turing parentheses are numbered one. Thus, when  the  pattern  matches,
+       you  can  look  at captured substring number one, whichever alternative
+       matched. This construct is useful when you want to  capture  part,  but
+       not all, of one of a number of alternatives. Inside a (?| group, paren-
+       theses are numbered as usual, but the number is reset at the  start  of
+       each  branch.  The numbers of any capturing parentheses that follow the
+       subpattern start after the highest number used in any branch. The  fol-
+       lowing example is taken from the Perl documentation. The numbers under-
+       neath show in which buffer the captured content will be stored.
+
+         # before  ---------------branch-reset----------- after
+         / ( a )  (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
+         # 1            2         2  3        2     3     4
+
+       A back reference to a numbered subpattern uses the  most  recent  value
+       that  is  set  for that number by any subpattern. The following pattern
+       matches "abcabc" or "defdef":
+
+         /(?|(abc)|(def))\1/
+
+       In contrast, a subroutine call to a numbered subpattern  always  refers
+       to  the  first  one in the pattern with the given number. The following
+       pattern matches "abcabc" or "defabc":
+
+         /(?|(abc)|(def))(?1)/
+
+       If a condition test for a subpattern's having matched refers to a  non-
+       unique  number, the test is true if any of the subpatterns of that num-
+       ber have matched.
+
+       An alternative approach to using this "branch reset" feature is to  use
+       duplicate named subpatterns, as described in the next section.
+
+
+NAMED SUBPATTERNS
+
+       Identifying  capturing  parentheses  by number is simple, but it can be
+       very hard to keep track of the numbers in complicated  regular  expres-
+       sions.  Furthermore,  if  an  expression  is  modified, the numbers may
+       change. To help with this difficulty, PCRE supports the naming of  sub-
+       patterns. This feature was not added to Perl until release 5.10. Python
+       had the feature earlier, and PCRE introduced it at release  4.0,  using
+       the  Python syntax. PCRE now supports both the Perl and the Python syn-
+       tax. Perl allows identically numbered  subpatterns  to  have  different
+       names, but PCRE does not.
+
+       In  PCRE,  a subpattern can be named in one of three ways: (?...)
+       or (?'name'...) as in Perl, or (?P...) as in  Python.  References
+       to  capturing parentheses from other parts of the pattern, such as back
+       references, recursion, and conditions, can be made by name as  well  as
+       by number.
+
+       Names  consist of up to 32 alphanumeric characters and underscores, but
+       must start with a non-digit.  Named  capturing  parentheses  are  still
+       allocated  numbers  as  well as names, exactly as if the names were not
+       present. The PCRE API provides function calls for extracting the  name-
+       to-number  translation  table  from a compiled pattern. There is also a
+       convenience function for extracting a captured substring by name.
+
+       By default, a name must be unique within a pattern, but it is  possible
+       to relax this constraint by setting the PCRE_DUPNAMES option at compile
+       time. (Duplicate names are also always permitted for  subpatterns  with
+       the  same  number, set up as described in the previous section.) Dupli-
+       cate names can be useful for patterns where only one  instance  of  the
+       named  parentheses  can  match. Suppose you want to match the name of a
+       weekday, either as a 3-letter abbreviation or as the full name, and  in
+       both cases you want to extract the abbreviation. This pattern (ignoring
+       the line breaks) does the job:
+
+         (?Mon|Fri|Sun)(?:day)?|
+         (?Tue)(?:sday)?|
+         (?Wed)(?:nesday)?|
+         (?Thu)(?:rsday)?|
+         (?Sat)(?:urday)?
+
+       There are five capturing substrings, but only one is ever set  after  a
+       match.  (An alternative way of solving this problem is to use a "branch
+       reset" subpattern, as described in the previous section.)
+
+       The convenience function for extracting the data by  name  returns  the
+       substring  for  the first (and in this example, the only) subpattern of
+       that name that matched. This saves searching  to  find  which  numbered
+       subpattern it was.
+
+       If  you  make  a  back  reference to a non-unique named subpattern from
+       elsewhere in the pattern, the subpatterns to which the name refers  are
+       checked  in  the order in which they appear in the overall pattern. The
+       first one that is set is used for the reference. For example, this pat-
+       tern matches both "foofoo" and "barbar" but not "foobar" or "barfoo":
+
+         (?:(?foo)|(?bar))\k
+
+
+       If you make a subroutine call to a non-unique named subpattern, the one
+       that corresponds to the first occurrence of the name is  used.  In  the
+       absence of duplicate numbers (see the previous section) this is the one
+       with the lowest number.
+
+       If you use a named reference in a condition test (see the section about
+       conditions below), either to check whether a subpattern has matched, or
+       to check for recursion, all subpatterns with the same name are  tested.
+       If  the condition is true for any one of them, the overall condition is
+       true. This is the same behaviour as  testing  by  number.  For  further
+       details  of  the  interfaces  for  handling  named subpatterns, see the
+       pcreapi documentation.
+
+       Warning: You cannot use different names to distinguish between two sub-
+       patterns  with  the same number because PCRE uses only the numbers when
+       matching. For this reason, an error is given at compile time if differ-
+       ent  names  are given to subpatterns with the same number. However, you
+       can always give the same name to subpatterns with the same number, even
+       when PCRE_DUPNAMES is not set.
+
+
+REPETITION
+
+       Repetition  is  specified  by  quantifiers, which can follow any of the
+       following items:
+
+         a literal data character
+         the dot metacharacter
+         the \C escape sequence
+         the \X escape sequence
+         the \R escape sequence
+         an escape such as \d or \pL that matches a single character
+         a character class
+         a back reference (see next section)
+         a parenthesized subpattern (including assertions)
+         a subroutine call to a subpattern (recursive or otherwise)
+
+       The general repetition quantifier specifies a minimum and maximum  num-
+       ber  of  permitted matches, by giving the two numbers in curly brackets
+       (braces), separated by a comma. The numbers must be  less  than  65536,
+       and the first must be less than or equal to the second. For example:
+
+         z{2,4}
+
+       matches  "zz",  "zzz",  or  "zzzz". A closing brace on its own is not a
+       special character. If the second number is omitted, but  the  comma  is
+       present,  there  is  no upper limit; if the second number and the comma
+       are both omitted, the quantifier specifies an exact number of  required
+       matches. Thus
+
+         [aeiou]{3,}
+
+       matches at least 3 successive vowels, but may match many more, while
+
+         \d{8}
+
+       matches  exactly  8  digits. An opening curly bracket that appears in a
+       position where a quantifier is not allowed, or one that does not  match
+       the  syntax of a quantifier, is taken as a literal character. For exam-
+       ple, {,6} is not a quantifier, but a literal string of four characters.
+
+       In UTF modes, quantifiers apply to characters rather than to individual
+       data  units. Thus, for example, \x{100}{2} matches two characters, each
+       of which is represented by a two-byte sequence in a UTF-8 string. Simi-
+       larly,  \X{3} matches three Unicode extended grapheme clusters, each of
+       which may be several data units long (and  they  may  be  of  different
+       lengths).
+
+       The quantifier {0} is permitted, causing the expression to behave as if
+       the previous item and the quantifier were not present. This may be use-
+       ful  for  subpatterns that are referenced as subroutines from elsewhere
+       in the pattern (but see also the section entitled "Defining subpatterns
+       for  use  by  reference only" below). Items other than subpatterns that
+       have a {0} quantifier are omitted from the compiled pattern.
+
+       For convenience, the three most common quantifiers have  single-charac-
+       ter abbreviations:
+
+         *    is equivalent to {0,}
+         +    is equivalent to {1,}
+         ?    is equivalent to {0,1}
+
+       It  is  possible  to construct infinite loops by following a subpattern
+       that can match no characters with a quantifier that has no upper limit,
+       for example:
+
+         (a?)*
+
+       Earlier versions of Perl and PCRE used to give an error at compile time
+       for such patterns. However, because there are cases where this  can  be
+       useful,  such  patterns  are now accepted, but if any repetition of the
+       subpattern does in fact match no characters, the loop is forcibly  bro-
+       ken.
+
+       By  default,  the quantifiers are "greedy", that is, they match as much
+       as possible (up to the maximum  number  of  permitted  times),  without
+       causing  the  rest of the pattern to fail. The classic example of where
+       this gives problems is in trying to match comments in C programs. These
+       appear  between  /*  and  */ and within the comment, individual * and /
+       characters may appear. An attempt to match C comments by  applying  the
+       pattern
+
+         /\*.*\*/
+
+       to the string
+
+         /* first comment */  not comment  /* second comment */
+
+       fails,  because it matches the entire string owing to the greediness of
+       the .*  item.
+
+       However, if a quantifier is followed by a question mark, it  ceases  to
+       be greedy, and instead matches the minimum number of times possible, so
+       the pattern
+
+         /\*.*?\*/
+
+       does the right thing with the C comments. The meaning  of  the  various
+       quantifiers  is  not  otherwise  changed,  just the preferred number of
+       matches.  Do not confuse this use of question mark with its  use  as  a
+       quantifier  in its own right. Because it has two uses, it can sometimes
+       appear doubled, as in
+
+         \d??\d
+
+       which matches one digit by preference, but can match two if that is the
+       only way the rest of the pattern matches.
+
+       If  the PCRE_UNGREEDY option is set (an option that is not available in
+       Perl), the quantifiers are not greedy by default, but  individual  ones
+       can  be  made  greedy  by following them with a question mark. In other
+       words, it inverts the default behaviour.
+
+       When a parenthesized subpattern is quantified  with  a  minimum  repeat
+       count  that is greater than 1 or with a limited maximum, more memory is
+       required for the compiled pattern, in proportion to  the  size  of  the
+       minimum or maximum.
+
+       If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equiv-
+       alent to Perl's /s) is set, thus allowing the dot  to  match  newlines,
+       the  pattern  is  implicitly anchored, because whatever follows will be
+       tried against every character position in the subject string, so  there
+       is  no  point  in  retrying the overall match at any position after the
+       first. PCRE normally treats such a pattern as though it  were  preceded
+       by \A.
+
+       In  cases  where  it  is known that the subject string contains no new-
+       lines, it is worth setting PCRE_DOTALL in order to  obtain  this  opti-
+       mization, or alternatively using ^ to indicate anchoring explicitly.
+
+       However,  there  are  some cases where the optimization cannot be used.
+       When .*  is inside capturing parentheses that are the subject of a back
+       reference elsewhere in the pattern, a match at the start may fail where
+       a later one succeeds. Consider, for example:
+
+         (.*)abc\1
+
+       If the subject is "xyz123abc123" the match point is the fourth  charac-
+       ter. For this reason, such a pattern is not implicitly anchored.
+
+       Another  case where implicit anchoring is not applied is when the lead-
+       ing .* is inside an atomic group. Once again, a match at the start  may
+       fail where a later one succeeds. Consider this pattern:
+
+         (?>.*?a)b
+
+       It  matches "ab" in the subject "aab". The use of the backtracking con-
+       trol verbs (*PRUNE) and (*SKIP) also disable this optimization.
+
+       When a capturing subpattern is repeated, the value captured is the sub-
+       string that matched the final iteration. For example, after
+
+         (tweedle[dume]{3}\s*)+
+
+       has matched "tweedledum tweedledee" the value of the captured substring
+       is "tweedledee". However, if there are  nested  capturing  subpatterns,
+       the  corresponding captured values may have been set in previous itera-
+       tions. For example, after
+
+         /(a|(b))+/
+
+       matches "aba" the value of the second captured substring is "b".
+
+
+ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
+
+       With both maximizing ("greedy") and minimizing ("ungreedy"  or  "lazy")
+       repetition,  failure  of what follows normally causes the repeated item
+       to be re-evaluated to see if a different number of repeats  allows  the
+       rest  of  the pattern to match. Sometimes it is useful to prevent this,
+       either to change the nature of the match, or to cause it  fail  earlier
+       than  it otherwise might, when the author of the pattern knows there is
+       no point in carrying on.
+
+       Consider, for example, the pattern \d+foo when applied to  the  subject
+       line
+
+         123456bar
+
+       After matching all 6 digits and then failing to match "foo", the normal
+       action of the matcher is to try again with only 5 digits  matching  the
+       \d+  item,  and  then  with  4,  and  so on, before ultimately failing.
+       "Atomic grouping" (a term taken from Jeffrey  Friedl's  book)  provides
+       the  means for specifying that once a subpattern has matched, it is not
+       to be re-evaluated in this way.
+
+       If we use atomic grouping for the previous example, the  matcher  gives
+       up  immediately  on failing to match "foo" the first time. The notation
+       is a kind of special parenthesis, starting with (?> as in this example:
+
+         (?>\d+)foo
+
+       This kind of parenthesis "locks up" the  part of the  pattern  it  con-
+       tains  once  it  has matched, and a failure further into the pattern is
+       prevented from backtracking into it. Backtracking past it  to  previous
+       items, however, works as normal.
+
+       An  alternative  description  is that a subpattern of this type matches
+       the string of characters that an  identical  standalone  pattern  would
+       match, if anchored at the current point in the subject string.
+
+       Atomic grouping subpatterns are not capturing subpatterns. Simple cases
+       such as the above example can be thought of as a maximizing repeat that
+       must  swallow  everything  it can. So, while both \d+ and \d+? are pre-
+       pared to adjust the number of digits they match in order  to  make  the
+       rest of the pattern match, (?>\d+) can only match an entire sequence of
+       digits.
+
+       Atomic groups in general can of course contain arbitrarily  complicated
+       subpatterns,  and  can  be  nested. However, when the subpattern for an
+       atomic group is just a single repeated item, as in the example above, a
+       simpler  notation,  called  a "possessive quantifier" can be used. This
+       consists of an additional + character  following  a  quantifier.  Using
+       this notation, the previous example can be rewritten as
+
+         \d++foo
+
+       Note that a possessive quantifier can be used with an entire group, for
+       example:
+
+         (abc|xyz){2,3}+
+
+       Possessive  quantifiers  are  always  greedy;  the   setting   of   the
+       PCRE_UNGREEDY option is ignored. They are a convenient notation for the
+       simpler forms of atomic group. However, there is no difference  in  the
+       meaning  of  a  possessive  quantifier and the equivalent atomic group,
+       though there may be a performance  difference;  possessive  quantifiers
+       should be slightly faster.
+
+       The  possessive  quantifier syntax is an extension to the Perl 5.8 syn-
+       tax.  Jeffrey Friedl originated the idea (and the name)  in  the  first
+       edition of his book. Mike McCloskey liked it, so implemented it when he
+       built Sun's Java package, and PCRE copied it from there. It  ultimately
+       found its way into Perl at release 5.10.
+
+       PCRE has an optimization that automatically "possessifies" certain sim-
+       ple pattern constructs. For example, the sequence  A+B  is  treated  as
+       A++B  because  there is no point in backtracking into a sequence of A's
+       when B must follow.
+
+       When a pattern contains an unlimited repeat inside  a  subpattern  that
+       can  itself  be  repeated  an  unlimited number of times, the use of an
+       atomic group is the only way to avoid some  failing  matches  taking  a
+       very long time indeed. The pattern
+
+         (\D+|<\d+>)*[!?]
+
+       matches  an  unlimited number of substrings that either consist of non-
+       digits, or digits enclosed in <>, followed by either ! or  ?.  When  it
+       matches, it runs quickly. However, if it is applied to
+
+         aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+
+       it  takes  a  long  time  before reporting failure. This is because the
+       string can be divided between the internal \D+ repeat and the  external
+       *  repeat  in  a  large  number of ways, and all have to be tried. (The
+       example uses [!?] rather than a single character at  the  end,  because
+       both  PCRE  and  Perl have an optimization that allows for fast failure
+       when a single character is used. They remember the last single  charac-
+       ter  that  is required for a match, and fail early if it is not present
+       in the string.) If the pattern is changed so that  it  uses  an  atomic
+       group, like this:
+
+         ((?>\D+)|<\d+>)*[!?]
+
+       sequences of non-digits cannot be broken, and failure happens quickly.
+
+
+BACK REFERENCES
+
+       Outside a character class, a backslash followed by a digit greater than
+       0 (and possibly further digits) is a back reference to a capturing sub-
+       pattern  earlier  (that is, to its left) in the pattern, provided there
+       have been that many previous capturing left parentheses.
+
+       However, if the decimal number following the backslash is less than 10,
+       it  is  always  taken  as a back reference, and causes an error only if
+       there are not that many capturing left parentheses in the  entire  pat-
+       tern.  In  other words, the parentheses that are referenced need not be
+       to the left of the reference for numbers less than 10. A "forward  back
+       reference"  of  this  type can make sense when a repetition is involved
+       and the subpattern to the right has participated in an  earlier  itera-
+       tion.
+
+       It  is  not  possible to have a numerical "forward back reference" to a
+       subpattern whose number is 10 or  more  using  this  syntax  because  a
+       sequence  such  as  \50 is interpreted as a character defined in octal.
+       See the subsection entitled "Non-printing characters" above for further
+       details  of  the  handling of digits following a backslash. There is no
+       such problem when named parentheses are used. A back reference  to  any
+       subpattern is possible using named parentheses (see below).
+
+       Another  way  of  avoiding  the ambiguity inherent in the use of digits
+       following a backslash is to use the \g  escape  sequence.  This  escape
+       must be followed by an unsigned number or a negative number, optionally
+       enclosed in braces. These examples are all identical:
+
+         (ring), \1
+         (ring), \g1
+         (ring), \g{1}
+
+       An unsigned number specifies an absolute reference without the  ambigu-
+       ity that is present in the older syntax. It is also useful when literal
+       digits follow the reference. A negative number is a relative reference.
+       Consider this example:
+
+         (abc(def)ghi)\g{-1}
+
+       The sequence \g{-1} is a reference to the most recently started captur-
+       ing subpattern before \g, that is, is it equivalent to \2 in this exam-
+       ple.   Similarly, \g{-2} would be equivalent to \1. The use of relative
+       references can be helpful in long patterns, and also in  patterns  that
+       are  created  by  joining  together  fragments  that contain references
+       within themselves.
+
+       A back reference matches whatever actually matched the  capturing  sub-
+       pattern  in  the  current subject string, rather than anything matching
+       the subpattern itself (see "Subpatterns as subroutines" below for a way
+       of doing that). So the pattern
+
+         (sens|respons)e and \1ibility
+
+       matches  "sense and sensibility" and "response and responsibility", but
+       not "sense and responsibility". If caseful matching is in force at  the
+       time  of the back reference, the case of letters is relevant. For exam-
+       ple,
+
+         ((?i)rah)\s+\1
+
+       matches "rah rah" and "RAH RAH", but not "RAH  rah",  even  though  the
+       original capturing subpattern is matched caselessly.
+
+       There  are  several  different ways of writing back references to named
+       subpatterns. The .NET syntax \k{name} and the Perl syntax  \k  or
+       \k'name'  are supported, as is the Python syntax (?P=name). Perl 5.10's
+       unified back reference syntax, in which \g can be used for both numeric
+       and  named  references,  is  also supported. We could rewrite the above
+       example in any of the following ways:
+
+         (?(?i)rah)\s+\k
+         (?'p1'(?i)rah)\s+\k{p1}
+         (?P(?i)rah)\s+(?P=p1)
+         (?(?i)rah)\s+\g{p1}
+
+       A subpattern that is referenced by  name  may  appear  in  the  pattern
+       before or after the reference.
+
+       There  may be more than one back reference to the same subpattern. If a
+       subpattern has not actually been used in a particular match,  any  back
+       references to it always fail by default. For example, the pattern
+
+         (a|(bc))\2
+
+       always  fails  if  it starts to match "a" rather than "bc". However, if
+       the PCRE_JAVASCRIPT_COMPAT option is set at compile time, a back refer-
+       ence to an unset value matches an empty string.
+
+       Because  there may be many capturing parentheses in a pattern, all dig-
+       its following a backslash are taken as part of a potential back  refer-
+       ence  number.   If  the  pattern continues with a digit character, some
+       delimiter must  be  used  to  terminate  the  back  reference.  If  the
+       PCRE_EXTENDED  option  is  set, this can be white space. Otherwise, the
+       \g{ syntax or an empty comment (see "Comments" below) can be used.
+
+   Recursive back references
+
+       A back reference that occurs inside the parentheses to which it  refers
+       fails  when  the subpattern is first used, so, for example, (a\1) never
+       matches.  However, such references can be useful inside  repeated  sub-
+       patterns. For example, the pattern
+
+         (a|b\1)+
+
+       matches any number of "a"s and also "aba", "ababbaa" etc. At each iter-
+       ation of the subpattern,  the  back  reference  matches  the  character
+       string  corresponding  to  the previous iteration. In order for this to
+       work, the pattern must be such that the first iteration does  not  need
+       to  match the back reference. This can be done using alternation, as in
+       the example above, or by a quantifier with a minimum of zero.
+
+       Back references of this type cause the group that they reference to  be
+       treated  as  an atomic group.  Once the whole group has been matched, a
+       subsequent matching failure cannot cause backtracking into  the  middle
+       of the group.
+
+
+ASSERTIONS
+
+       An  assertion  is  a  test on the characters following or preceding the
+       current matching point that does not actually consume  any  characters.
+       The  simple  assertions  coded  as  \b, \B, \A, \G, \Z, \z, ^ and $ are
+       described above.
+
+       More complicated assertions are coded as  subpatterns.  There  are  two
+       kinds:  those  that  look  ahead of the current position in the subject
+       string, and those that look  behind  it.  An  assertion  subpattern  is
+       matched  in  the  normal way, except that it does not cause the current
+       matching position to be changed.
+
+       Assertion subpatterns are not capturing subpatterns. If such an  asser-
+       tion  contains  capturing  subpatterns within it, these are counted for
+       the purposes of numbering the capturing subpatterns in the  whole  pat-
+       tern.  However,  substring  capturing  is carried out only for positive
+       assertions. (Perl sometimes, but not always, does do capturing in nega-
+       tive assertions.)
+
+       For  compatibility  with  Perl,  assertion subpatterns may be repeated;
+       though it makes no sense to assert the same thing  several  times,  the
+       side  effect  of  capturing  parentheses may occasionally be useful. In
+       practice, there only three cases:
+
+       (1) If the quantifier is {0}, the  assertion  is  never  obeyed  during
+       matching.   However,  it  may  contain internal capturing parenthesized
+       groups that are called from elsewhere via the subroutine mechanism.
+
+       (2) If quantifier is {0,n} where n is greater than zero, it is  treated
+       as  if  it  were  {0,1}.  At run time, the rest of the pattern match is
+       tried with and without the assertion, the order depending on the greed-
+       iness of the quantifier.
+
+       (3)  If  the minimum repetition is greater than zero, the quantifier is
+       ignored.  The assertion is obeyed just  once  when  encountered  during
+       matching.
+
+   Lookahead assertions
+
+       Lookahead assertions start with (?= for positive assertions and (?! for
+       negative assertions. For example,
+
+         \w+(?=;)
+
+       matches a word followed by a semicolon, but does not include the  semi-
+       colon in the match, and
+
+         foo(?!bar)
+
+       matches  any  occurrence  of  "foo" that is not followed by "bar". Note
+       that the apparently similar pattern
+
+         (?!foo)bar
+
+       does not find an occurrence of "bar"  that  is  preceded  by  something
+       other  than "foo"; it finds any occurrence of "bar" whatsoever, because
+       the assertion (?!foo) is always true when the next three characters are
+       "bar". A lookbehind assertion is needed to achieve the other effect.
+
+       If you want to force a matching failure at some point in a pattern, the
+       most convenient way to do it is  with  (?!)  because  an  empty  string
+       always  matches, so an assertion that requires there not to be an empty
+       string must always fail.  The backtracking control verb (*FAIL) or (*F)
+       is a synonym for (?!).
+
+   Lookbehind assertions
+
+       Lookbehind  assertions start with (?<= for positive assertions and (?)...) or (?('name')...)  to  test  for  a
+       used  subpattern  by  name.  For compatibility with earlier versions of
+       PCRE, which had this facility before Perl, the syntax  (?(name)...)  is
+       also recognized.
+
+       Rewriting the above example to use a named subpattern gives this:
+
+         (? \( )?    [^()]+    (?() \) )
+
+       If  the  name used in a condition of this kind is a duplicate, the test
+       is applied to all subpatterns of the same name, and is true if any  one
+       of them has matched.
+
+   Checking for pattern recursion
+
+       If the condition is the string (R), and there is no subpattern with the
+       name R, the condition is true if a recursive call to the whole  pattern
+       or any subpattern has been made. If digits or a name preceded by amper-
+       sand follow the letter R, for example:
+
+         (?(R3)...) or (?(R&name)...)
+
+       the condition is true if the most recent recursion is into a subpattern
+       whose number or name is given. This condition does not check the entire
+       recursion stack. If the name used in a condition  of  this  kind  is  a
+       duplicate, the test is applied to all subpatterns of the same name, and
+       is true if any one of them is the most recent recursion.
+
+       At "top level", all these recursion test  conditions  are  false.   The
+       syntax for recursive patterns is described below.
+
+   Defining subpatterns for use by reference only
+
+       If  the  condition  is  the string (DEFINE), and there is no subpattern
+       with the name DEFINE, the condition is  always  false.  In  this  case,
+       there  may  be  only  one  alternative  in the subpattern. It is always
+       skipped if control reaches this point  in  the  pattern;  the  idea  of
+       DEFINE  is that it can be used to define subroutines that can be refer-
+       enced from elsewhere. (The use of subroutines is described below.)  For
+       example,  a  pattern  to match an IPv4 address such as "192.168.23.245"
+       could be written like this (ignore white space and line breaks):
+
+         (?(DEFINE) (? 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) )
+         \b (?&byte) (\.(?&byte)){3} \b
+
+       The first part of the pattern is a DEFINE group inside which a  another
+       group  named "byte" is defined. This matches an individual component of
+       an IPv4 address (a number less than 256). When  matching  takes  place,
+       this  part  of  the pattern is skipped because DEFINE acts like a false
+       condition. The rest of the pattern uses references to the  named  group
+       to  match the four dot-separated components of an IPv4 address, insist-
+       ing on a word boundary at each end.
+
+   Assertion conditions
+
+       If the condition is not in any of the above  formats,  it  must  be  an
+       assertion.   This may be a positive or negative lookahead or lookbehind
+       assertion. Consider  this  pattern,  again  containing  non-significant
+       white space, and with the two alternatives on the second line:
+
+         (?(?=[^a-z]*[a-z])
+         \d{2}-[a-z]{3}-\d{2}  |  \d{2}-\d{2}-\d{2} )
+
+       The  condition  is  a  positive  lookahead  assertion  that  matches an
+       optional sequence of non-letters followed by a letter. In other  words,
+       it  tests  for the presence of at least one letter in the subject. If a
+       letter is found, the subject is matched against the first  alternative;
+       otherwise  it  is  matched  against  the  second.  This pattern matches
+       strings in one of the two forms dd-aaa-dd or dd-dd-dd,  where  aaa  are
+       letters and dd are digits.
+
+
+COMMENTS
+
+       There are two ways of including comments in patterns that are processed
+       by PCRE. In both cases, the start of the comment must not be in a char-
+       acter class, nor in the middle of any other sequence of related charac-
+       ters such as (?: or a subpattern name or number.  The  characters  that
+       make up a comment play no part in the pattern matching.
+
+       The  sequence (?# marks the start of a comment that continues up to the
+       next closing parenthesis. Nested parentheses are not permitted. If  the
+       PCRE_EXTENDED option is set, an unescaped # character also introduces a
+       comment, which in this case continues to  immediately  after  the  next
+       newline  character  or character sequence in the pattern. Which charac-
+       ters are interpreted as newlines is controlled by the options passed to
+       a  compiling function or by a special sequence at the start of the pat-
+       tern, as described in the section entitled "Newline conventions" above.
+       Note that the end of this type of comment is a literal newline sequence
+       in the pattern; escape sequences that happen to represent a newline  do
+       not  count.  For  example,  consider this pattern when PCRE_EXTENDED is
+       set, and the default newline convention is in force:
+
+         abc #comment \n still comment
+
+       On encountering the # character, pcre_compile()  skips  along,  looking
+       for  a newline in the pattern. The sequence \n is still literal at this
+       stage, so it does not terminate the comment. Only an  actual  character
+       with the code value 0x0a (the default newline) does so.
+
+
+RECURSIVE PATTERNS
+
+       Consider  the problem of matching a string in parentheses, allowing for
+       unlimited nested parentheses. Without the use of  recursion,  the  best
+       that  can  be  done  is  to use a pattern that matches up to some fixed
+       depth of nesting. It is not possible to  handle  an  arbitrary  nesting
+       depth.
+
+       For some time, Perl has provided a facility that allows regular expres-
+       sions to recurse (amongst other things). It does this by  interpolating
+       Perl  code in the expression at run time, and the code can refer to the
+       expression itself. A Perl pattern using code interpolation to solve the
+       parentheses problem can be created like this:
+
+         $re = qr{\( (?: (?>[^()]+) | (?p{$re}) )* \)}x;
+
+       The (?p{...}) item interpolates Perl code at run time, and in this case
+       refers recursively to the pattern in which it appears.
+
+       Obviously, PCRE cannot support the interpolation of Perl code. Instead,
+       it  supports  special  syntax  for recursion of the entire pattern, and
+       also for individual subpattern recursion.  After  its  introduction  in
+       PCRE  and  Python,  this  kind of recursion was subsequently introduced
+       into Perl at release 5.10.
+
+       A special item that consists of (? followed by a  number  greater  than
+       zero  and  a  closing parenthesis is a recursive subroutine call of the
+       subpattern of the given number, provided that  it  occurs  inside  that
+       subpattern.  (If  not,  it is a non-recursive subroutine call, which is
+       described in the next section.) The special item  (?R)  or  (?0)  is  a
+       recursive call of the entire regular expression.
+
+       This  PCRE  pattern  solves  the nested parentheses problem (assume the
+       PCRE_EXTENDED option is set so that white space is ignored):
+
+         \( ( [^()]++ | (?R) )* \)
+
+       First it matches an opening parenthesis. Then it matches any number  of
+       substrings  which  can  either  be  a sequence of non-parentheses, or a
+       recursive match of the pattern itself (that is, a  correctly  parenthe-
+       sized substring).  Finally there is a closing parenthesis. Note the use
+       of a possessive quantifier to avoid backtracking into sequences of non-
+       parentheses.
+
+       If  this  were  part of a larger pattern, you would not want to recurse
+       the entire pattern, so instead you could use this:
+
+         ( \( ( [^()]++ | (?1) )* \) )
+
+       We have put the pattern into parentheses, and caused the  recursion  to
+       refer to them instead of the whole pattern.
+
+       In  a  larger  pattern,  keeping  track  of  parenthesis numbers can be
+       tricky. This is made easier by the use of relative references.  Instead
+       of (?1) in the pattern above you can write (?-2) to refer to the second
+       most recently opened parentheses  preceding  the  recursion.  In  other
+       words,  a  negative  number counts capturing parentheses leftwards from
+       the point at which it is encountered.
+
+       It is also possible to refer to  subsequently  opened  parentheses,  by
+       writing  references  such  as (?+2). However, these cannot be recursive
+       because the reference is not inside the  parentheses  that  are  refer-
+       enced.  They are always non-recursive subroutine calls, as described in
+       the next section.
+
+       An alternative approach is to use named parentheses instead.  The  Perl
+       syntax  for  this  is (?&name); PCRE's earlier syntax (?P>name) is also
+       supported. We could rewrite the above example as follows:
+
+         (? \( ( [^()]++ | (?&pn) )* \) )
+
+       If there is more than one subpattern with the same name,  the  earliest
+       one is used.
+
+       This  particular  example pattern that we have been looking at contains
+       nested unlimited repeats, and so the use of a possessive quantifier for
+       matching strings of non-parentheses is important when applying the pat-
+       tern to strings that do not match. For example, when  this  pattern  is
+       applied to
+
+         (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
+
+       it  yields  "no  match" quickly. However, if a possessive quantifier is
+       not used, the match runs for a very long time indeed because there  are
+       so  many  different  ways the + and * repeats can carve up the subject,
+       and all have to be tested before failure can be reported.
+
+       At the end of a match, the values of capturing  parentheses  are  those
+       from  the outermost level. If you want to obtain intermediate values, a
+       callout function can be used (see below and the pcrecallout  documenta-
+       tion). If the pattern above is matched against
+
+         (ab(cd)ef)
+
+       the  value  for  the  inner capturing parentheses (numbered 2) is "ef",
+       which is the last value taken on at the top level. If a capturing  sub-
+       pattern  is  not  matched at the top level, its final captured value is
+       unset, even if it was (temporarily) set at a deeper  level  during  the
+       matching process.
+
+       If  there are more than 15 capturing parentheses in a pattern, PCRE has
+       to obtain extra memory to store data during a recursion, which it  does
+       by using pcre_malloc, freeing it via pcre_free afterwards. If no memory
+       can be obtained, the match fails with the PCRE_ERROR_NOMEMORY error.
+
+       Do not confuse the (?R) item with the condition (R),  which  tests  for
+       recursion.   Consider  this pattern, which matches text in angle brack-
+       ets, allowing for arbitrary nesting. Only digits are allowed in  nested
+       brackets  (that is, when recursing), whereas any characters are permit-
+       ted at the outer level.
+
+         < (?: (?(R) \d++  | [^<>]*+) | (?R)) * >
+
+       In this pattern, (?(R) is the start of a conditional  subpattern,  with
+       two  different  alternatives for the recursive and non-recursive cases.
+       The (?R) item is the actual recursive call.
+
+   Differences in recursion processing between PCRE and Perl
+
+       Recursion processing in PCRE differs from Perl in two  important  ways.
+       In  PCRE (like Python, but unlike Perl), a recursive subpattern call is
+       always treated as an atomic group. That is, once it has matched some of
+       the subject string, it is never re-entered, even if it contains untried
+       alternatives and there is a subsequent matching failure.  This  can  be
+       illustrated  by the following pattern, which purports to match a palin-
+       dromic string that contains an odd number of characters  (for  example,
+       "a", "aba", "abcba", "abcdcba"):
+
+         ^(.|(.)(?1)\2)$
+
+       The idea is that it either matches a single character, or two identical
+       characters surrounding a sub-palindrome. In Perl, this  pattern  works;
+       in  PCRE  it  does  not if the pattern is longer than three characters.
+       Consider the subject string "abcba":
+
+       At the top level, the first character is matched, but as it is  not  at
+       the end of the string, the first alternative fails; the second alterna-
+       tive is taken and the recursion kicks in. The recursive call to subpat-
+       tern  1  successfully  matches the next character ("b"). (Note that the
+       beginning and end of line tests are not part of the recursion).
+
+       Back at the top level, the next character ("c") is compared  with  what
+       subpattern  2 matched, which was "a". This fails. Because the recursion
+       is treated as an atomic group, there are now  no  backtracking  points,
+       and  so  the  entire  match fails. (Perl is able, at this point, to re-
+       enter the recursion and try the second alternative.)  However,  if  the
+       pattern is written with the alternatives in the other order, things are
+       different:
+
+         ^((.)(?1)\2|.)$
+
+       This time, the recursing alternative is tried first, and  continues  to
+       recurse  until  it runs out of characters, at which point the recursion
+       fails. But this time we do have  another  alternative  to  try  at  the
+       higher  level.  That  is  the  big difference: in the previous case the
+       remaining alternative is at a deeper recursion level, which PCRE cannot
+       use.
+
+       To  change  the pattern so that it matches all palindromic strings, not
+       just those with an odd number of characters, it is tempting  to  change
+       the pattern to this:
+
+         ^((.)(?1)\2|.?)$
+
+       Again,  this  works  in Perl, but not in PCRE, and for the same reason.
+       When a deeper recursion has matched a single character,  it  cannot  be
+       entered  again  in  order  to match an empty string. The solution is to
+       separate the two cases, and write out the odd and even cases as  alter-
+       natives at the higher level:
+
+         ^(?:((.)(?1)\2|)|((.)(?3)\4|.))
+
+       If  you  want  to match typical palindromic phrases, the pattern has to
+       ignore all non-word characters, which can be done like this:
+
+         ^\W*+(?:((.)\W*+(?1)\W*+\2|)|((.)\W*+(?3)\W*+\4|\W*+.\W*+))\W*+$
+
+       If run with the PCRE_CASELESS option, this pattern matches phrases such
+       as "A man, a plan, a canal: Panama!" and it works well in both PCRE and
+       Perl. Note the use of the possessive quantifier *+ to avoid  backtrack-
+       ing  into  sequences of non-word characters. Without this, PCRE takes a
+       great deal longer (ten times or more) to  match  typical  phrases,  and
+       Perl takes so long that you think it has gone into a loop.
+
+       WARNING:  The  palindrome-matching patterns above work only if the sub-
+       ject string does not start with a palindrome that is shorter  than  the
+       entire  string.  For example, although "abcba" is correctly matched, if
+       the subject is "ababa", PCRE finds the palindrome "aba" at  the  start,
+       then  fails at top level because the end of the string does not follow.
+       Once again, it cannot jump back into the recursion to try other  alter-
+       natives, so the entire match fails.
+
+       The  second  way  in which PCRE and Perl differ in their recursion pro-
+       cessing is in the handling of captured values. In Perl, when a  subpat-
+       tern  is  called recursively or as a subpattern (see the next section),
+       it has no access to any values that were captured  outside  the  recur-
+       sion,  whereas  in  PCRE  these values can be referenced. Consider this
+       pattern:
+
+         ^(.)(\1|a(?2))
+
+       In PCRE, this pattern matches "bab". The  first  capturing  parentheses
+       match  "b",  then in the second group, when the back reference \1 fails
+       to match "b", the second alternative matches "a" and then recurses.  In
+       the  recursion,  \1 does now match "b" and so the whole match succeeds.
+       In Perl, the pattern fails to match because inside the  recursive  call
+       \1 cannot access the externally set value.
+
+
+SUBPATTERNS AS SUBROUTINES
+
+       If  the  syntax for a recursive subpattern call (either by number or by
+       name) is used outside the parentheses to which it refers,  it  operates
+       like  a subroutine in a programming language. The called subpattern may
+       be defined before or after the reference. A numbered reference  can  be
+       absolute or relative, as in these examples:
+
+         (...(absolute)...)...(?2)...
+         (...(relative)...)...(?-1)...
+         (...(?+1)...(relative)...
+
+       An earlier example pointed out that the pattern
+
+         (sens|respons)e and \1ibility
+
+       matches  "sense and sensibility" and "response and responsibility", but
+       not "sense and responsibility". If instead the pattern
+
+         (sens|respons)e and (?1)ibility
+
+       is used, it does match "sense and responsibility" as well as the  other
+       two  strings.  Another  example  is  given  in the discussion of DEFINE
+       above.
+
+       All subroutine calls, whether recursive or not, are always  treated  as
+       atomic  groups. That is, once a subroutine has matched some of the sub-
+       ject string, it is never re-entered, even if it contains untried alter-
+       natives  and  there  is  a  subsequent  matching failure. Any capturing
+       parentheses that are set during the subroutine  call  revert  to  their
+       previous values afterwards.
+
+       Processing  options  such as case-independence are fixed when a subpat-
+       tern is defined, so if it is used as a subroutine, such options  cannot
+       be changed for different calls. For example, consider this pattern:
+
+         (abc)(?i:(?-1))
+
+       It  matches  "abcabc". It does not match "abcABC" because the change of
+       processing option does not affect the called subpattern.
+
+
+ONIGURUMA SUBROUTINE SYNTAX
+
+       For compatibility with Oniguruma, the non-Perl syntax \g followed by  a
+       name or a number enclosed either in angle brackets or single quotes, is
+       an alternative syntax for referencing a  subpattern  as  a  subroutine,
+       possibly  recursively. Here are two of the examples used above, rewrit-
+       ten using this syntax:
+
+         (? \( ( (?>[^()]+) | \g )* \) )
+         (sens|respons)e and \g'1'ibility
+
+       PCRE supports an extension to Oniguruma: if a number is preceded  by  a
+       plus or a minus sign it is taken as a relative reference. For example:
+
+         (abc)(?i:\g<-1>)
+
+       Note  that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not
+       synonymous. The former is a back reference; the latter is a  subroutine
+       call.
+
+
+CALLOUTS
+
+       Perl has a feature whereby using the sequence (?{...}) causes arbitrary
+       Perl code to be obeyed in the middle of matching a regular  expression.
+       This makes it possible, amongst other things, to extract different sub-
+       strings that match the same pair of parentheses when there is a repeti-
+       tion.
+
+       PCRE provides a similar feature, but of course it cannot obey arbitrary
+       Perl code. The feature is called "callout". The caller of PCRE provides
+       an  external function by putting its entry point in the global variable
+       pcre_callout (8-bit library) or pcre[16|32]_callout (16-bit  or  32-bit
+       library).   By default, this variable contains NULL, which disables all
+       calling out.
+
+       Within a regular expression, (?C) indicates the  points  at  which  the
+       external  function  is  to be called. If you want to identify different
+       callout points, you can put a number less than 256 after the letter  C.
+       The  default  value is zero.  For example, this pattern has two callout
+       points:
+
+         (?C1)abc(?C2)def
+
+       If the PCRE_AUTO_CALLOUT flag is passed to a compiling function,  call-
+       outs  are automatically installed before each item in the pattern. They
+       are all numbered 255. If there is a conditional group  in  the  pattern
+       whose condition is an assertion, an additional callout is inserted just
+       before the condition. An explicit callout may also be set at this posi-
+       tion, as in this example:
+
+         (?(?C9)(?=a)abc|def)
+
+       Note that this applies only to assertion conditions, not to other types
+       of condition.
+
+       During matching, when PCRE reaches a callout point, the external  func-
+       tion  is  called.  It  is  provided with the number of the callout, the
+       position in the pattern, and, optionally, one item of  data  originally
+       supplied  by  the caller of the matching function. The callout function
+       may cause matching to proceed, to backtrack, or to fail altogether.
+
+       By default, PCRE implements a number of optimizations at  compile  time
+       and  matching  time, and one side-effect is that sometimes callouts are
+       skipped. If you need all possible callouts to happen, you need  to  set
+       options  that  disable  the relevant optimizations. More details, and a
+       complete description of the interface  to  the  callout  function,  are
+       given in the pcrecallout documentation.
+
+
+BACKTRACKING CONTROL
+
+       Perl  5.10 introduced a number of "Special Backtracking Control Verbs",
+       which are still described in the Perl  documentation  as  "experimental
+       and  subject to change or removal in a future version of Perl". It goes
+       on to say: "Their usage in production code should  be  noted  to  avoid
+       problems  during upgrades." The same remarks apply to the PCRE features
+       described in this section.
+
+       The new verbs make use of what was previously invalid syntax: an  open-
+       ing parenthesis followed by an asterisk. They are generally of the form
+       (*VERB) or (*VERB:NAME). Some may take either form,  possibly  behaving
+       differently  depending  on  whether or not a name is present. A name is
+       any sequence of characters that does not include a closing parenthesis.
+       The maximum length of name is 255 in the 8-bit library and 65535 in the
+       16-bit and 32-bit libraries. If the name is  empty,  that  is,  if  the
+       closing  parenthesis immediately follows the colon, the effect is as if
+       the colon were not there.  Any number of these verbs  may  occur  in  a
+       pattern.
+
+       Since  these  verbs  are  specifically related to backtracking, most of
+       them can be used only when the pattern is to be matched  using  one  of
+       the  traditional  matching  functions, because these use a backtracking
+       algorithm. With the exception of (*FAIL), which behaves like a  failing
+       negative  assertion,  the  backtracking control verbs cause an error if
+       encountered by a DFA matching function.
+
+       The behaviour of these verbs in repeated  groups,  assertions,  and  in
+       subpatterns called as subroutines (whether or not recursively) is docu-
+       mented below.
+
+   Optimizations that affect backtracking verbs
+
+       PCRE contains some optimizations that are used to speed up matching  by
+       running some checks at the start of each match attempt. For example, it
+       may know the minimum length of matching subject, or that  a  particular
+       character must be present. When one of these optimizations bypasses the
+       running of a match,  any  included  backtracking  verbs  will  not,  of
+       course, be processed. You can suppress the start-of-match optimizations
+       by setting the PCRE_NO_START_OPTIMIZE  option  when  calling  pcre_com-
+       pile() or pcre_exec(), or by starting the pattern with (*NO_START_OPT).
+       There is more discussion of this option in the section entitled "Option
+       bits for pcre_exec()" in the pcreapi documentation.
+
+       Experiments  with  Perl  suggest that it too has similar optimizations,
+       sometimes leading to anomalous results.
+
+   Verbs that act immediately
+
+       The following verbs act as soon as they are encountered. They  may  not
+       be followed by a name.
+
+          (*ACCEPT)
+
+       This  verb causes the match to end successfully, skipping the remainder
+       of the pattern. However, when it is inside a subpattern that is  called
+       as  a  subroutine, only that subpattern is ended successfully. Matching
+       then continues at the outer level. If (*ACCEPT) in triggered in a posi-
+       tive  assertion,  the  assertion succeeds; in a negative assertion, the
+       assertion fails.
+
+       If (*ACCEPT) is inside capturing parentheses, the data so far  is  cap-
+       tured. For example:
+
+         A((?:A|B(*ACCEPT)|C)D)
+
+       This  matches  "AB", "AAD", or "ACD"; when it matches "AB", "B" is cap-
+       tured by the outer parentheses.
+
+         (*FAIL) or (*F)
+
+       This verb causes a matching failure, forcing backtracking to occur.  It
+       is  equivalent to (?!) but easier to read. The Perl documentation notes
+       that it is probably useful only when combined  with  (?{})  or  (??{}).
+       Those  are,  of course, Perl features that are not present in PCRE. The
+       nearest equivalent is the callout feature, as for example in this  pat-
+       tern:
+
+         a+(?C)(*FAIL)
+
+       A  match  with the string "aaaa" always fails, but the callout is taken
+       before each backtrack happens (in this example, 10 times).
+
+   Recording which path was taken
+
+       There is one verb whose main purpose  is  to  track  how  a  match  was
+       arrived  at,  though  it  also  has a secondary use in conjunction with
+       advancing the match starting point (see (*SKIP) below).
+
+         (*MARK:NAME) or (*:NAME)
+
+       A name is always  required  with  this  verb.  There  may  be  as  many
+       instances  of  (*MARK) as you like in a pattern, and their names do not
+       have to be unique.
+
+       When a match succeeds, the name of the  last-encountered  (*MARK:NAME),
+       (*PRUNE:NAME),  or  (*THEN:NAME) on the matching path is passed back to
+       the caller as  described  in  the  section  entitled  "Extra  data  for
+       pcre_exec()"  in  the  pcreapi  documentation.  Here  is  an example of
+       pcretest output, where the /K modifier requests the retrieval and  out-
+       putting of (*MARK) data:
+
+           re> /X(*MARK:A)Y|X(*MARK:B)Z/K
+         data> XY
+          0: XY
+         MK: A
+         XZ
+          0: XZ
+         MK: B
+
+       The (*MARK) name is tagged with "MK:" in this output, and in this exam-
+       ple it indicates which of the two alternatives matched. This is a  more
+       efficient  way of obtaining this information than putting each alterna-
+       tive in its own capturing parentheses.
+
+       If a verb with a name is encountered in a positive  assertion  that  is
+       true,  the  name  is recorded and passed back if it is the last-encoun-
+       tered. This does not happen for negative assertions or failing positive
+       assertions.
+
+       After  a  partial match or a failed match, the last encountered name in
+       the entire match process is returned. For example:
+
+           re> /X(*MARK:A)Y|X(*MARK:B)Z/K
+         data> XP
+         No match, mark = B
+
+       Note that in this unanchored example the  mark  is  retained  from  the
+       match attempt that started at the letter "X" in the subject. Subsequent
+       match attempts starting at "P" and then with an empty string do not get
+       as far as the (*MARK) item, but nevertheless do not reset it.
+
+       If  you  are  interested  in  (*MARK)  values after failed matches, you
+       should probably set the PCRE_NO_START_OPTIMIZE option  (see  above)  to
+       ensure that the match is always attempted.
+
+   Verbs that act after backtracking
+
+       The following verbs do nothing when they are encountered. Matching con-
+       tinues with what follows, but if there is no subsequent match,  causing
+       a  backtrack  to  the  verb, a failure is forced. That is, backtracking
+       cannot pass to the left of the verb. However, when one of  these  verbs
+       appears inside an atomic group or an assertion that is true, its effect
+       is confined to that group, because once the  group  has  been  matched,
+       there  is never any backtracking into it. In this situation, backtrack-
+       ing can "jump back" to the left of the entire atomic  group  or  asser-
+       tion.  (Remember  also,  as  stated  above, that this localization also
+       applies in subroutine calls.)
+
+       These verbs differ in exactly what kind of failure  occurs  when  back-
+       tracking  reaches  them.  The behaviour described below is what happens
+       when the verb is not in a subroutine or an assertion.  Subsequent  sec-
+       tions cover these special cases.
+
+         (*COMMIT)
+
+       This  verb, which may not be followed by a name, causes the whole match
+       to fail outright if there is a later matching failure that causes back-
+       tracking  to  reach  it.  Even if the pattern is unanchored, no further
+       attempts to find a match by advancing the starting point take place. If
+       (*COMMIT)  is  the  only backtracking verb that is encountered, once it
+       has been passed pcre_exec() is committed to finding a match at the cur-
+       rent starting point, or not at all. For example:
+
+         a+(*COMMIT)b
+
+       This  matches  "xxaab" but not "aacaab". It can be thought of as a kind
+       of dynamic anchor, or "I've started, so I must finish." The name of the
+       most  recently passed (*MARK) in the path is passed back when (*COMMIT)
+       forces a match failure.
+
+       If there is more than one backtracking verb in a pattern,  a  different
+       one  that  follows  (*COMMIT) may be triggered first, so merely passing
+       (*COMMIT) during a match does not always guarantee that a match must be
+       at this starting point.
+
+       Note  that  (*COMMIT)  at  the start of a pattern is not the same as an
+       anchor, unless PCRE's start-of-match optimizations are turned  off,  as
+       shown in this output from pcretest:
+
+           re> /(*COMMIT)abc/
+         data> xyzabc
+          0: abc
+         data> xyzabc\Y
+         No match
+
+       For this pattern, PCRE knows that any match must start with "a", so the
+       optimization skips along the subject to "a" before applying the pattern
+       to  the first set of data. The match attempt then succeeds. In the sec-
+       ond set of data, the escape sequence \Y is interpreted by the  pcretest
+       program.  It  causes  the  PCRE_NO_START_OPTIMIZE option to be set when
+       pcre_exec() is called.  This disables the optimization that skips along
+       to the first character. The pattern is now applied starting at "x", and
+       so the (*COMMIT) causes the match to  fail  without  trying  any  other
+       starting points.
+
+         (*PRUNE) or (*PRUNE:NAME)
+
+       This  verb causes the match to fail at the current starting position in
+       the subject if there is a later matching failure that causes backtrack-
+       ing  to  reach it. If the pattern is unanchored, the normal "bumpalong"
+       advance to the next starting character then happens.  Backtracking  can
+       occur  as  usual to the left of (*PRUNE), before it is reached, or when
+       matching to the right of (*PRUNE), but if there  is  no  match  to  the
+       right,  backtracking cannot cross (*PRUNE). In simple cases, the use of
+       (*PRUNE) is just an alternative to an atomic group or possessive  quan-
+       tifier, but there are some uses of (*PRUNE) that cannot be expressed in
+       any other way. In an anchored pattern (*PRUNE) has the same  effect  as
+       (*COMMIT).
+
+       The   behaviour   of   (*PRUNE:NAME)   is   the   not   the   same   as
+       (*MARK:NAME)(*PRUNE).  It is like (*MARK:NAME)  in  that  the  name  is
+       remembered  for  passing  back  to  the  caller.  However, (*SKIP:NAME)
+       searches only for names set with (*MARK).
+
+         (*SKIP)
+
+       This verb, when given without a name, is like (*PRUNE), except that  if
+       the  pattern  is unanchored, the "bumpalong" advance is not to the next
+       character, but to the position in the subject where (*SKIP) was encoun-
+       tered.  (*SKIP)  signifies that whatever text was matched leading up to
+       it cannot be part of a successful match. Consider:
+
+         a+(*SKIP)b
+
+       If the subject is "aaaac...",  after  the  first  match  attempt  fails
+       (starting  at  the  first  character in the string), the starting point
+       skips on to start the next attempt at "c". Note that a possessive quan-
+       tifer  does not have the same effect as this example; although it would
+       suppress backtracking  during  the  first  match  attempt,  the  second
+       attempt  would  start at the second character instead of skipping on to
+       "c".
+
+         (*SKIP:NAME)
+
+       When (*SKIP) has an associated name, its behaviour is modified. When it
+       is triggered, the previous path through the pattern is searched for the
+       most recent (*MARK) that has the  same  name.  If  one  is  found,  the
+       "bumpalong" advance is to the subject position that corresponds to that
+       (*MARK) instead of to where (*SKIP) was encountered. If no (*MARK) with
+       a matching name is found, the (*SKIP) is ignored.
+
+       Note  that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It
+       ignores names that are set by (*PRUNE:NAME) or (*THEN:NAME).
+
+         (*THEN) or (*THEN:NAME)
+
+       This verb causes a skip to the next innermost  alternative  when  back-
+       tracking  reaches  it.  That  is,  it  cancels any further backtracking
+       within the current alternative. Its name  comes  from  the  observation
+       that it can be used for a pattern-based if-then-else block:
+
+         ( COND1 (*THEN) FOO | COND2 (*THEN) BAR | COND3 (*THEN) BAZ ) ...
+
+       If  the COND1 pattern matches, FOO is tried (and possibly further items
+       after the end of the group if FOO succeeds); on  failure,  the  matcher
+       skips  to  the second alternative and tries COND2, without backtracking
+       into COND1. If that succeeds and BAR fails, COND3 is tried.  If  subse-
+       quently  BAZ fails, there are no more alternatives, so there is a back-
+       track to whatever came before the  entire  group.  If  (*THEN)  is  not
+       inside an alternation, it acts like (*PRUNE).
+
+       The    behaviour   of   (*THEN:NAME)   is   the   not   the   same   as
+       (*MARK:NAME)(*THEN).  It is like  (*MARK:NAME)  in  that  the  name  is
+       remembered  for  passing  back  to  the  caller.  However, (*SKIP:NAME)
+       searches only for names set with (*MARK).
+
+       A subpattern that does not contain a | character is just a part of  the
+       enclosing  alternative;  it  is  not a nested alternation with only one
+       alternative. The effect of (*THEN) extends beyond such a subpattern  to
+       the  enclosing alternative. Consider this pattern, where A, B, etc. are
+       complex pattern fragments that do not contain any | characters at  this
+       level:
+
+         A (B(*THEN)C) | D
+
+       If  A and B are matched, but there is a failure in C, matching does not
+       backtrack into A; instead it moves to the next alternative, that is, D.
+       However,  if the subpattern containing (*THEN) is given an alternative,
+       it behaves differently:
+
+         A (B(*THEN)C | (*FAIL)) | D
+
+       The effect of (*THEN) is now confined to the inner subpattern. After  a
+       failure in C, matching moves to (*FAIL), which causes the whole subpat-
+       tern to fail because there are no more alternatives  to  try.  In  this
+       case, matching does now backtrack into A.
+
+       Note  that  a  conditional  subpattern  is not considered as having two
+       alternatives, because only one is ever used.  In  other  words,  the  |
+       character in a conditional subpattern has a different meaning. Ignoring
+       white space, consider:
+
+         ^.*? (?(?=a) a | b(*THEN)c )
+
+       If the subject is "ba", this pattern does not  match.  Because  .*?  is
+       ungreedy,  it  initially  matches  zero characters. The condition (?=a)
+       then fails, the character "b" is matched,  but  "c"  is  not.  At  this
+       point,  matching does not backtrack to .*? as might perhaps be expected
+       from the presence of the | character.  The  conditional  subpattern  is
+       part of the single alternative that comprises the whole pattern, and so
+       the match fails. (If there was a backtrack into  .*?,  allowing  it  to
+       match "b", the match would succeed.)
+
+       The  verbs just described provide four different "strengths" of control
+       when subsequent matching fails. (*THEN) is the weakest, carrying on the
+       match  at  the next alternative. (*PRUNE) comes next, failing the match
+       at the current starting position, but allowing an advance to  the  next
+       character  (for an unanchored pattern). (*SKIP) is similar, except that
+       the advance may be more than one character. (*COMMIT) is the strongest,
+       causing the entire match to fail.
+
+   More than one backtracking verb
+
+       If  more  than  one  backtracking verb is present in a pattern, the one
+       that is backtracked onto first acts. For example,  consider  this  pat-
+       tern, where A, B, etc. are complex pattern fragments:
+
+         (A(*COMMIT)B(*THEN)C|ABD)
+
+       If  A matches but B fails, the backtrack to (*COMMIT) causes the entire
+       match to fail. However, if A and B match, but C fails, the backtrack to
+       (*THEN)  causes  the next alternative (ABD) to be tried. This behaviour
+       is consistent, but is not always the same as Perl's. It means  that  if
+       two  or  more backtracking verbs appear in succession, all the the last
+       of them has no effect. Consider this example:
+
+         ...(*COMMIT)(*PRUNE)...
+
+       If there is a matching failure to the right, backtracking onto (*PRUNE)
+       causes  it to be triggered, and its action is taken. There can never be
+       a backtrack onto (*COMMIT).
+
+   Backtracking verbs in repeated groups
+
+       PCRE differs from  Perl  in  its  handling  of  backtracking  verbs  in
+       repeated groups. For example, consider:
+
+         /(a(*COMMIT)b)+ac/
+
+       If  the  subject  is  "abac",  Perl matches, but PCRE fails because the
+       (*COMMIT) in the second repeat of the group acts.
+
+   Backtracking verbs in assertions
+
+       (*FAIL) in an assertion has its normal effect: it forces  an  immediate
+       backtrack.
+
+       (*ACCEPT) in a positive assertion causes the assertion to succeed with-
+       out any further processing. In a negative assertion,  (*ACCEPT)  causes
+       the assertion to fail without any further processing.
+
+       The  other  backtracking verbs are not treated specially if they appear
+       in a positive assertion. In  particular,  (*THEN)  skips  to  the  next
+       alternative  in  the  innermost  enclosing group that has alternations,
+       whether or not this is within the assertion.
+
+       Negative assertions are, however, different, in order  to  ensure  that
+       changing  a  positive  assertion  into a negative assertion changes its
+       result. Backtracking into (*COMMIT), (*SKIP), or (*PRUNE) causes a neg-
+       ative assertion to be true, without considering any further alternative
+       branches in the assertion.  Backtracking into (*THEN) causes it to skip
+       to  the next enclosing alternative within the assertion (the normal be-
+       haviour), but if the assertion  does  not  have  such  an  alternative,
+       (*THEN) behaves like (*PRUNE).
+
+   Backtracking verbs in subroutines
+
+       These  behaviours  occur whether or not the subpattern is called recur-
+       sively.  Perl's treatment of subroutines is different in some cases.
+
+       (*FAIL) in a subpattern called as a subroutine has its  normal  effect:
+       it forces an immediate backtrack.
+
+       (*ACCEPT)  in a subpattern called as a subroutine causes the subroutine
+       match to succeed without any further processing. Matching then  contin-
+       ues after the subroutine call.
+
+       (*COMMIT), (*SKIP), and (*PRUNE) in a subpattern called as a subroutine
+       cause the subroutine match to fail.
+
+       (*THEN) skips to the next alternative in the innermost enclosing  group
+       within  the subpattern that has alternatives. If there is no such group
+       within the subpattern, (*THEN) causes the subroutine match to fail.
+
+
+SEE ALSO
+
+       pcreapi(3), pcrecallout(3),  pcrematching(3),  pcresyntax(3),  pcre(3),
+       pcre16(3), pcre32(3).
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 08 January 2014
+       Copyright (c) 1997-2014 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCRESYNTAX(3)              Library Functions Manual              PCRESYNTAX(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+PCRE REGULAR EXPRESSION SYNTAX SUMMARY
+
+       The  full syntax and semantics of the regular expressions that are sup-
+       ported by PCRE are described in  the  pcrepattern  documentation.  This
+       document contains a quick-reference summary of the syntax.
+
+
+QUOTING
+
+         \x         where x is non-alphanumeric is a literal x
+         \Q...\E    treat enclosed characters as literal
+
+
+CHARACTERS
+
+         \a         alarm, that is, the BEL character (hex 07)
+         \cx        "control-x", where x is any ASCII character
+         \e         escape (hex 1B)
+         \f         form feed (hex 0C)
+         \n         newline (hex 0A)
+         \r         carriage return (hex 0D)
+         \t         tab (hex 09)
+         \0dd       character with octal code 0dd
+         \ddd       character with octal code ddd, or backreference
+         \o{ddd..}  character with octal code ddd..
+         \xhh       character with hex code hh
+         \x{hhh..}  character with hex code hhh..
+
+       Note that \0dd is always an octal code, and that \8 and \9 are the lit-
+       eral characters "8" and "9".
+
+
+CHARACTER TYPES
+
+         .          any character except newline;
+                      in dotall mode, any character whatsoever
+         \C         one data unit, even in UTF mode (best avoided)
+         \d         a decimal digit
+         \D         a character that is not a decimal digit
+         \h         a horizontal white space character
+         \H         a character that is not a horizontal white space character
+         \N         a character that is not a newline
+         \p{xx}     a character with the xx property
+         \P{xx}     a character without the xx property
+         \R         a newline sequence
+         \s         a white space character
+         \S         a character that is not a white space character
+         \v         a vertical white space character
+         \V         a character that is not a vertical white space character
+         \w         a "word" character
+         \W         a "non-word" character
+         \X         a Unicode extended grapheme cluster
+
+       By default, \d, \s, and \w match only ASCII characters, even  in  UTF-8
+       mode  or  in  the 16- bit and 32-bit libraries. However, if locale-spe-
+       cific matching is happening, \s and \w may also match  characters  with
+       code  points  in  the range 128-255. If the PCRE_UCP option is set, the
+       behaviour of these escape sequences is changed to use  Unicode  proper-
+       ties and they match many more characters.
+
+
+GENERAL CATEGORY PROPERTIES FOR \p and \P
+
+         C          Other
+         Cc         Control
+         Cf         Format
+         Cn         Unassigned
+         Co         Private use
+         Cs         Surrogate
+
+         L          Letter
+         Ll         Lower case letter
+         Lm         Modifier letter
+         Lo         Other letter
+         Lt         Title case letter
+         Lu         Upper case letter
+         L&         Ll, Lu, or Lt
+
+         M          Mark
+         Mc         Spacing mark
+         Me         Enclosing mark
+         Mn         Non-spacing mark
+
+         N          Number
+         Nd         Decimal number
+         Nl         Letter number
+         No         Other number
+
+         P          Punctuation
+         Pc         Connector punctuation
+         Pd         Dash punctuation
+         Pe         Close punctuation
+         Pf         Final punctuation
+         Pi         Initial punctuation
+         Po         Other punctuation
+         Ps         Open punctuation
+
+         S          Symbol
+         Sc         Currency symbol
+         Sk         Modifier symbol
+         Sm         Mathematical symbol
+         So         Other symbol
+
+         Z          Separator
+         Zl         Line separator
+         Zp         Paragraph separator
+         Zs         Space separator
+
+
+PCRE SPECIAL CATEGORY PROPERTIES FOR \p and \P
+
+         Xan        Alphanumeric: union of properties L and N
+         Xps        POSIX space: property Z or tab, NL, VT, FF, CR
+         Xsp        Perl space: property Z or tab, NL, VT, FF, CR
+         Xuc        Univerally-named character: one that can be
+                      represented by a Universal Character Name
+         Xwd        Perl word: property Xan or underscore
+
+       Perl and POSIX space are now the same. Perl added VT to its space char-
+       acter set at release 5.18 and PCRE changed at release 8.34.
+
+
+SCRIPT NAMES FOR \p AND \P
+
+       Arabic, Armenian, Avestan, Balinese, Bamum, Batak,  Bengali,  Bopomofo,
+       Brahmi,  Braille, Buginese, Buhid, Canadian_Aboriginal, Carian, Chakma,
+       Cham, Cherokee, Common, Coptic, Cuneiform, Cypriot, Cyrillic,  Deseret,
+       Devanagari,   Egyptian_Hieroglyphs,   Ethiopic,  Georgian,  Glagolitic,
+       Gothic, Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew,  Hira-
+       gana,   Imperial_Aramaic,  Inherited,  Inscriptional_Pahlavi,  Inscrip-
+       tional_Parthian,  Javanese,  Kaithi,   Kannada,   Katakana,   Kayah_Li,
+       Kharoshthi,  Khmer,  Lao, Latin, Lepcha, Limbu, Linear_B, Lisu, Lycian,
+       Lydian,    Malayalam,    Mandaic,    Meetei_Mayek,    Meroitic_Cursive,
+       Meroitic_Hieroglyphs,   Miao,  Mongolian,  Myanmar,  New_Tai_Lue,  Nko,
+       Ogham,   Old_Italic,   Old_Persian,   Old_South_Arabian,    Old_Turkic,
+       Ol_Chiki,  Oriya, Osmanya, Phags_Pa, Phoenician, Rejang, Runic, Samari-
+       tan, Saurashtra, Sharada, Shavian,  Sinhala,  Sora_Sompeng,  Sundanese,
+       Syloti_Nagri,  Syriac,  Tagalog,  Tagbanwa, Tai_Le, Tai_Tham, Tai_Viet,
+       Takri, Tamil, Telugu, Thaana, Thai, Tibetan, Tifinagh,  Ugaritic,  Vai,
+       Yi.
+
+
+CHARACTER CLASSES
+
+         [...]       positive character class
+         [^...]      negative character class
+         [x-y]       range (can be used for hex characters)
+         [[:xxx:]]   positive POSIX named set
+         [[:^xxx:]]  negative POSIX named set
+
+         alnum       alphanumeric
+         alpha       alphabetic
+         ascii       0-127
+         blank       space or tab
+         cntrl       control character
+         digit       decimal digit
+         graph       printing, excluding space
+         lower       lower case letter
+         print       printing, including space
+         punct       printing, excluding alphanumeric
+         space       white space
+         upper       upper case letter
+         word        same as \w
+         xdigit      hexadecimal digit
+
+       In  PCRE,  POSIX character set names recognize only ASCII characters by
+       default, but some of them use Unicode properties if  PCRE_UCP  is  set.
+       You can use \Q...\E inside a character class.
+
+
+QUANTIFIERS
+
+         ?           0 or 1, greedy
+         ?+          0 or 1, possessive
+         ??          0 or 1, lazy
+         *           0 or more, greedy
+         *+          0 or more, possessive
+         *?          0 or more, lazy
+         +           1 or more, greedy
+         ++          1 or more, possessive
+         +?          1 or more, lazy
+         {n}         exactly n
+         {n,m}       at least n, no more than m, greedy
+         {n,m}+      at least n, no more than m, possessive
+         {n,m}?      at least n, no more than m, lazy
+         {n,}        n or more, greedy
+         {n,}+       n or more, possessive
+         {n,}?       n or more, lazy
+
+
+ANCHORS AND SIMPLE ASSERTIONS
+
+         \b          word boundary
+         \B          not a word boundary
+         ^           start of subject
+                      also after internal newline in multiline mode
+         \A          start of subject
+         $           end of subject
+                      also before newline at end of subject
+                      also before internal newline in multiline mode
+         \Z          end of subject
+                      also before newline at end of subject
+         \z          end of subject
+         \G          first matching position in subject
+
+
+MATCH POINT RESET
+
+         \K          reset start of match
+
+       \K is honoured in positive assertions, but ignored in negative ones.
+
+
+ALTERNATION
+
+         expr|expr|expr...
+
+
+CAPTURING
+
+         (...)           capturing group
+         (?...)    named capturing group (Perl)
+         (?'name'...)    named capturing group (Perl)
+         (?P...)   named capturing group (Python)
+         (?:...)         non-capturing group
+         (?|...)         non-capturing group; reset group numbers for
+                          capturing groups in each alternative
+
+
+ATOMIC GROUPS
+
+         (?>...)         atomic, non-capturing group
+
+
+COMMENT
+
+         (?#....)        comment (not nestable)
+
+
+OPTION SETTING
+
+         (?i)            caseless
+         (?J)            allow duplicate names
+         (?m)            multiline
+         (?s)            single line (dotall)
+         (?U)            default ungreedy (lazy)
+         (?x)            extended (ignore white space)
+         (?-...)         unset option(s)
+
+       The  following  are  recognized  only at the very start of a pattern or
+       after one of the newline or \R options with similar syntax.  More  than
+       one of them may appear.
+
+         (*LIMIT_MATCH=d) set the match limit to d (decimal number)
+         (*LIMIT_RECURSION=d) set the recursion limit to d (decimal number)
+         (*NO_AUTO_POSSESS) no auto-possessification (PCRE_NO_AUTO_POSSESS)
+         (*NO_START_OPT) no start-match optimization (PCRE_NO_START_OPTIMIZE)
+         (*UTF8)         set UTF-8 mode: 8-bit library (PCRE_UTF8)
+         (*UTF16)        set UTF-16 mode: 16-bit library (PCRE_UTF16)
+         (*UTF32)        set UTF-32 mode: 32-bit library (PCRE_UTF32)
+         (*UTF)          set appropriate UTF mode for the library in use
+         (*UCP)          set PCRE_UCP (use Unicode properties for \d etc)
+
+       Note  that LIMIT_MATCH and LIMIT_RECURSION can only reduce the value of
+       the limits set by the caller of pcre_exec(), not increase them.
+
+
+NEWLINE CONVENTION
+
+       These are recognized only at the very start of  the  pattern  or  after
+       option settings with a similar syntax.
+
+         (*CR)           carriage return only
+         (*LF)           linefeed only
+         (*CRLF)         carriage return followed by linefeed
+         (*ANYCRLF)      all three of the above
+         (*ANY)          any Unicode newline sequence
+
+
+WHAT \R MATCHES
+
+       These  are  recognized  only  at the very start of the pattern or after
+       option setting with a similar syntax.
+
+         (*BSR_ANYCRLF)  CR, LF, or CRLF
+         (*BSR_UNICODE)  any Unicode newline sequence
+
+
+LOOKAHEAD AND LOOKBEHIND ASSERTIONS
+
+         (?=...)         positive look ahead
+         (?!...)         negative look ahead
+         (?<=...)        positive look behind
+         (?        reference by name (Perl)
+         \k'name'        reference by name (Perl)
+         \g{name}        reference by name (Perl)
+         \k{name}        reference by name (.NET)
+         (?P=name)       reference by name (Python)
+
+
+SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)
+
+         (?R)            recurse whole pattern
+         (?n)            call subpattern by absolute number
+         (?+n)           call subpattern by relative number
+         (?-n)           call subpattern by relative number
+         (?&name)        call subpattern by name (Perl)
+         (?P>name)       call subpattern by name (Python)
+         \g        call subpattern by name (Oniguruma)
+         \g'name'        call subpattern by name (Oniguruma)
+         \g           call subpattern by absolute number (Oniguruma)
+         \g'n'           call subpattern by absolute number (Oniguruma)
+         \g<+n>          call subpattern by relative number (PCRE extension)
+         \g'+n'          call subpattern by relative number (PCRE extension)
+         \g<-n>          call subpattern by relative number (PCRE extension)
+         \g'-n'          call subpattern by relative number (PCRE extension)
+
+
+CONDITIONAL PATTERNS
+
+         (?(condition)yes-pattern)
+         (?(condition)yes-pattern|no-pattern)
+
+         (?(n)...        absolute reference condition
+         (?(+n)...       relative reference condition
+         (?(-n)...       relative reference condition
+         (?()...   named reference condition (Perl)
+         (?('name')...   named reference condition (Perl)
+         (?(name)...     named reference condition (PCRE)
+         (?(R)...        overall recursion condition
+         (?(Rn)...       specific group recursion condition
+         (?(R&name)...   specific recursion condition
+         (?(DEFINE)...   define subpattern for reference
+         (?(assert)...   assertion condition
+
+
+BACKTRACKING CONTROL
+
+       The following act immediately they are reached:
+
+         (*ACCEPT)       force successful match
+         (*FAIL)         force backtrack; synonym (*F)
+         (*MARK:NAME)    set name to be passed back; synonym (*:NAME)
+
+       The following act only when a subsequent match failure causes  a  back-
+       track to reach them. They all force a match failure, but they differ in
+       what happens afterwards. Those that advance the start-of-match point do
+       so only if the pattern is not anchored.
+
+         (*COMMIT)       overall failure, no advance of starting point
+         (*PRUNE)        advance to next starting character
+         (*PRUNE:NAME)   equivalent to (*MARK:NAME)(*PRUNE)
+         (*SKIP)         advance to current matching position
+         (*SKIP:NAME)    advance to position corresponding to an earlier
+                         (*MARK:NAME); if not found, the (*SKIP) is ignored
+         (*THEN)         local failure, backtrack to next alternation
+         (*THEN:NAME)    equivalent to (*MARK:NAME)(*THEN)
+
+
+CALLOUTS
+
+         (?C)      callout
+         (?Cn)     callout with data n
+
+
+SEE ALSO
+
+       pcrepattern(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcre(3).
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 08 January 2014
+       Copyright (c) 1997-2014 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCREUNICODE(3)             Library Functions Manual             PCREUNICODE(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+UTF-8, UTF-16, UTF-32, AND UNICODE PROPERTY SUPPORT
+
+       As well as UTF-8 support, PCRE also supports UTF-16 (from release 8.30)
+       and UTF-32 (from release 8.32), by means of two  additional  libraries.
+       They can be built as well as, or instead of, the 8-bit library.
+
+
+UTF-8 SUPPORT
+
+       In  order  process  UTF-8  strings, you must build PCRE's 8-bit library
+       with UTF support, and, in addition, you must call  pcre_compile()  with
+       the  PCRE_UTF8 option flag, or the pattern must start with the sequence
+       (*UTF8) or (*UTF). When either of these is the case, both  the  pattern
+       and  any  subject  strings  that  are matched against it are treated as
+       UTF-8 strings instead of strings of individual 1-byte characters.
+
+
+UTF-16 AND UTF-32 SUPPORT
+
+       In order process UTF-16 or UTF-32 strings, you must build PCRE's 16-bit
+       or  32-bit  library  with  UTF support, and, in addition, you must call
+       pcre16_compile() or pcre32_compile() with the PCRE_UTF16 or  PCRE_UTF32
+       option flag, as appropriate. Alternatively, the pattern must start with
+       the sequence (*UTF16), (*UTF32), as appropriate, or (*UTF),  which  can
+       be used with either library. When UTF mode is set, both the pattern and
+       any subject strings that are matched against it are treated  as  UTF-16
+       or  UTF-32  strings  instead  of strings of individual 16-bit or 32-bit
+       characters.
+
+
+UTF SUPPORT OVERHEAD
+
+       If you compile PCRE with UTF support, but do not use it  at  run  time,
+       the  library will be a bit bigger, but the additional run time overhead
+       is limited to  testing  the  PCRE_UTF[8|16|32]  flag  occasionally,  so
+       should not be very big.
+
+
+UNICODE PROPERTY SUPPORT
+
+       If PCRE is built with Unicode character property support (which implies
+       UTF support), the escape sequences \p{..}, \P{..}, and \X can be  used.
+       The  available properties that can be tested are limited to the general
+       category properties such as Lu for an upper case letter  or  Nd  for  a
+       decimal number, the Unicode script names such as Arabic or Han, and the
+       derived properties Any and L&. Full lists is given in  the  pcrepattern
+       and  pcresyntax  documentation. Only the short names for properties are
+       supported. For example, \p{L}  matches  a  letter.  Its  Perl  synonym,
+       \p{Letter},  is  not  supported.  Furthermore, in Perl, many properties
+       may optionally be prefixed by "Is", for compatibility  with  Perl  5.6.
+       PCRE does not support this.
+
+   Validity of UTF-8 strings
+
+       When  you  set  the PCRE_UTF8 flag, the byte strings passed as patterns
+       and subjects are (by default) checked for validity on entry to the rel-
+       evant functions. The entire string is checked before any other process-
+       ing takes place. From release 7.3 of PCRE, the check is  according  the
+       rules of RFC 3629, which are themselves derived from the Unicode speci-
+       fication. Earlier releases of PCRE followed  the  rules  of  RFC  2279,
+       which  allows  the  full  range of 31-bit values (0 to 0x7FFFFFFF). The
+       current check allows only values in the range U+0 to U+10FFFF,  exclud-
+       ing  the  surrogate area. (From release 8.33 the so-called "non-charac-
+       ter" code points are no longer excluded because Unicode corrigendum  #9
+       makes it clear that they should not be.)
+
+       Characters  in  the "Surrogate Area" of Unicode are reserved for use by
+       UTF-16, where they are used in pairs to encode codepoints  with  values
+       greater  than  0xFFFF. The code points that are encoded by UTF-16 pairs
+       are available independently in the  UTF-8  and  UTF-32  encodings.  (In
+       other  words,  the  whole  surrogate  thing is a fudge for UTF-16 which
+       unfortunately messes up UTF-8 and UTF-32.)
+
+       If an invalid UTF-8 string is passed to PCRE, an error return is given.
+       At  compile  time, the only additional information is the offset to the
+       first byte of the failing character. The run-time functions pcre_exec()
+       and  pcre_dfa_exec() also pass back this information, as well as a more
+       detailed reason code if the caller has provided memory in which  to  do
+       this.
+
+       In  some  situations, you may already know that your strings are valid,
+       and therefore want to skip these checks in  order  to  improve  perfor-
+       mance,  for  example in the case of a long subject string that is being
+       scanned repeatedly.  If you set the PCRE_NO_UTF8_CHECK flag at  compile
+       time  or  at  run  time, PCRE assumes that the pattern or subject it is
+       given (respectively) contains only valid UTF-8 codes. In this case,  it
+       does not diagnose an invalid UTF-8 string.
+
+       Note  that  passing  PCRE_NO_UTF8_CHECK to pcre_compile() just disables
+       the check for the pattern; it does not also apply to  subject  strings.
+       If  you  want  to  disable the check for a subject string you must pass
+       this option to pcre_exec() or pcre_dfa_exec().
+
+       If you pass an invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set, the
+       result is undefined and your program may crash.
+
+   Validity of UTF-16 strings
+
+       When you set the PCRE_UTF16 flag, the strings of 16-bit data units that
+       are passed as patterns and subjects are (by default) checked for valid-
+       ity  on entry to the relevant functions. Values other than those in the
+       surrogate range U+D800 to U+DFFF are independent code points. Values in
+       the surrogate range must be used in pairs in the correct manner.
+
+       If  an  invalid  UTF-16  string  is  passed to PCRE, an error return is
+       given. At compile time, the only additional information is  the  offset
+       to the first data unit of the failing character. The run-time functions
+       pcre16_exec() and pcre16_dfa_exec() also pass back this information, as
+       well  as  a more detailed reason code if the caller has provided memory
+       in which to do this.
+
+       In some situations, you may already know that your strings  are  valid,
+       and  therefore  want  to  skip these checks in order to improve perfor-
+       mance. If you set the PCRE_NO_UTF16_CHECK flag at compile  time  or  at
+       run time, PCRE assumes that the pattern or subject it is given (respec-
+       tively) contains only valid UTF-16 sequences. In this case, it does not
+       diagnose  an  invalid  UTF-16 string.  However, if an invalid string is
+       passed, the result is undefined.
+
+   Validity of UTF-32 strings
+
+       When you set the PCRE_UTF32 flag, the strings of 32-bit data units that
+       are passed as patterns and subjects are (by default) checked for valid-
+       ity on entry to the relevant functions.  This check allows only  values
+       in  the  range  U+0 to U+10FFFF, excluding the surrogate area U+D800 to
+       U+DFFF.
+
+       If an invalid UTF-32 string is passed  to  PCRE,  an  error  return  is
+       given.  At  compile time, the only additional information is the offset
+       to the first data unit of the failing character. The run-time functions
+       pcre32_exec() and pcre32_dfa_exec() also pass back this information, as
+       well as a more detailed reason code if the caller has  provided  memory
+       in which to do this.
+
+       In  some  situations, you may already know that your strings are valid,
+       and therefore want to skip these checks in  order  to  improve  perfor-
+       mance.  If  you  set the PCRE_NO_UTF32_CHECK flag at compile time or at
+       run time, PCRE assumes that the pattern or subject it is given (respec-
+       tively) contains only valid UTF-32 sequences. In this case, it does not
+       diagnose an invalid UTF-32 string.  However, if an  invalid  string  is
+       passed, the result is undefined.
+
+   General comments about UTF modes
+
+       1.  Codepoints  less  than  256  can be specified in patterns by either
+       braced or unbraced hexadecimal escape sequences (for example, \x{b3} or
+       \xb3). Larger values have to use braced sequences.
+
+       2.  Octal  numbers  up  to  \777 are recognized, and in UTF-8 mode they
+       match two-byte characters for values greater than \177.
+
+       3. Repeat quantifiers apply to complete UTF characters, not to individ-
+       ual data units, for example: \x{100}{3}.
+
+       4.  The dot metacharacter matches one UTF character instead of a single
+       data unit.
+
+       5. The escape sequence \C can be used to match a single byte  in  UTF-8
+       mode,  or  a single 16-bit data unit in UTF-16 mode, or a single 32-bit
+       data unit in UTF-32 mode, but its use can lead to some strange  effects
+       because  it  breaks up multi-unit characters (see the description of \C
+       in the pcrepattern documentation). The use of \C is  not  supported  in
+       the  alternative  matching  function  pcre[16|32]_dfa_exec(), nor is it
+       supported in UTF mode by the JIT optimization of pcre[16|32]_exec(). If
+       JIT  optimization  is  requested for a UTF pattern that contains \C, it
+       will not succeed, and so the matching will be carried out by the normal
+       interpretive function.
+
+       6.  The  character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly
+       test characters of any code value, but, by default, the characters that
+       PCRE  recognizes  as digits, spaces, or word characters remain the same
+       set as in non-UTF mode, all with values less  than  256.  This  remains
+       true  even  when  PCRE  is  built  to include Unicode property support,
+       because to do otherwise would slow down PCRE in many common cases. Note
+       in  particular that this applies to \b and \B, because they are defined
+       in terms of \w and \W. If you really want to test for a wider sense of,
+       say,  "digit",  you  can  use  explicit  Unicode property tests such as
+       \p{Nd}. Alternatively, if you set the PCRE_UCP option, the way that the
+       character  escapes  work is changed so that Unicode properties are used
+       to determine which characters match. There are more details in the sec-
+       tion on generic character types in the pcrepattern documentation.
+
+       7.  Similarly,  characters that match the POSIX named character classes
+       are all low-valued characters, unless the PCRE_UCP option is set.
+
+       8. However, the horizontal and vertical white  space  matching  escapes
+       (\h,  \H,  \v, and \V) do match all the appropriate Unicode characters,
+       whether or not PCRE_UCP is set.
+
+       9. Case-insensitive matching applies only to  characters  whose  values
+       are  less than 128, unless PCRE is built with Unicode property support.
+       A few Unicode characters such as Greek sigma have more than  two  code-
+       points that are case-equivalent. Up to and including PCRE release 8.31,
+       only one-to-one case mappings were supported, but later releases  (with
+       Unicode  property  support) do treat as case-equivalent all versions of
+       characters such as Greek sigma.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 27 February 2013
+       Copyright (c) 1997-2013 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCREJIT(3)                 Library Functions Manual                 PCREJIT(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+PCRE JUST-IN-TIME COMPILER SUPPORT
+
+       Just-in-time  compiling  is a heavyweight optimization that can greatly
+       speed up pattern matching. However, it comes at the cost of extra  pro-
+       cessing before the match is performed. Therefore, it is of most benefit
+       when the same pattern is going to be matched many times. This does  not
+       necessarily  mean  many calls of a matching function; if the pattern is
+       not anchored, matching attempts may take place many  times  at  various
+       positions  in  the  subject, even for a single call.  Therefore, if the
+       subject string is very long, it may still pay to use  JIT  for  one-off
+       matches.
+
+       JIT  support  applies  only to the traditional Perl-compatible matching
+       function.  It does not apply when the DFA matching  function  is  being
+       used. The code for this support was written by Zoltan Herczeg.
+
+
+8-BIT, 16-BIT AND 32-BIT SUPPORT
+
+       JIT  support  is available for all of the 8-bit, 16-bit and 32-bit PCRE
+       libraries. To keep this documentation simple, only the 8-bit  interface
+       is described in what follows. If you are using the 16-bit library, sub-
+       stitute the  16-bit  functions  and  16-bit  structures  (for  example,
+       pcre16_jit_stack  instead  of  pcre_jit_stack).  If  you  are using the
+       32-bit library, substitute the 32-bit functions and  32-bit  structures
+       (for example, pcre32_jit_stack instead of pcre_jit_stack).
+
+
+AVAILABILITY OF JIT SUPPORT
+
+       JIT  support  is  an  optional  feature of PCRE. The "configure" option
+       --enable-jit (or equivalent CMake option) must  be  set  when  PCRE  is
+       built  if  you want to use JIT. The support is limited to the following
+       hardware platforms:
+
+         ARM v5, v7, and Thumb2
+         Intel x86 32-bit and 64-bit
+         MIPS 32-bit
+         Power PC 32-bit and 64-bit
+         SPARC 32-bit (experimental)
+
+       If --enable-jit is set on an unsupported platform, compilation fails.
+
+       A program that is linked with PCRE 8.20 or later can tell if  JIT  sup-
+       port  is  available  by  calling pcre_config() with the PCRE_CONFIG_JIT
+       option. The result is 1 when JIT is available, and  0  otherwise.  How-
+       ever, a simple program does not need to check this in order to use JIT.
+       The normal API is implemented in a way that falls back to the interpre-
+       tive code if JIT is not available. For programs that need the best pos-
+       sible performance, there is also a "fast path"  API  that  is  JIT-spe-
+       cific.
+
+       If  your program may sometimes be linked with versions of PCRE that are
+       older than 8.20, but you want to use JIT when it is available, you  can
+       test the values of PCRE_MAJOR and PCRE_MINOR, or the existence of a JIT
+       macro such as PCRE_CONFIG_JIT, for compile-time control of your code.
+
+
+SIMPLE USE OF JIT
+
+       You have to do two things to make use of the JIT support  in  the  sim-
+       plest way:
+
+         (1) Call pcre_study() with the PCRE_STUDY_JIT_COMPILE option for
+             each compiled pattern, and pass the resulting pcre_extra block to
+             pcre_exec().
+
+         (2) Use pcre_free_study() to free the pcre_extra block when it is
+             no  longer  needed,  instead  of  just  freeing it yourself. This
+       ensures that
+             any JIT data is also freed.
+
+       For a program that may be linked with pre-8.20 versions  of  PCRE,  you
+       can insert
+
+         #ifndef PCRE_STUDY_JIT_COMPILE
+         #define PCRE_STUDY_JIT_COMPILE 0
+         #endif
+
+       so  that  no  option  is passed to pcre_study(), and then use something
+       like this to free the study data:
+
+         #ifdef PCRE_CONFIG_JIT
+             pcre_free_study(study_ptr);
+         #else
+             pcre_free(study_ptr);
+         #endif
+
+       PCRE_STUDY_JIT_COMPILE requests the JIT compiler to generate  code  for
+       complete  matches.  If  you  want  to  run  partial  matches  using the
+       PCRE_PARTIAL_HARD or  PCRE_PARTIAL_SOFT  options  of  pcre_exec(),  you
+       should  set  one  or  both  of the following options in addition to, or
+       instead of, PCRE_STUDY_JIT_COMPILE when you call pcre_study():
+
+         PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+         PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+
+       The JIT compiler generates different optimized code  for  each  of  the
+       three  modes  (normal, soft partial, hard partial). When pcre_exec() is
+       called, the appropriate code is run if it is available. Otherwise,  the
+       pattern is matched using interpretive code.
+
+       In  some circumstances you may need to call additional functions. These
+       are described in the  section  entitled  "Controlling  the  JIT  stack"
+       below.
+
+       If  JIT  support  is  not  available,  PCRE_STUDY_JIT_COMPILE  etc. are
+       ignored, and no JIT data is created. Otherwise, the compiled pattern is
+       passed  to the JIT compiler, which turns it into machine code that exe-
+       cutes much faster than the normal interpretive code.  When  pcre_exec()
+       is  passed  a  pcre_extra block containing a pointer to JIT code of the
+       appropriate mode (normal or hard/soft  partial),  it  obeys  that  code
+       instead  of  running  the interpreter. The result is identical, but the
+       compiled JIT code runs much faster.
+
+       There are some pcre_exec() options that are not supported for JIT  exe-
+       cution.  There  are  also  some  pattern  items that JIT cannot handle.
+       Details are given below. In both cases, execution  automatically  falls
+       back  to  the  interpretive  code.  If you want to know whether JIT was
+       actually used for a particular match, you  should  arrange  for  a  JIT
+       callback  function  to  be  set up as described in the section entitled
+       "Controlling the JIT stack" below, even if you do not need to supply  a
+       non-default  JIT stack. Such a callback function is called whenever JIT
+       code is about to be obeyed. If the execution options are not right  for
+       JIT execution, the callback function is not obeyed.
+
+       If  the  JIT  compiler finds an unsupported item, no JIT data is gener-
+       ated. You can find out if JIT execution is available after  studying  a
+       pattern  by  calling  pcre_fullinfo()  with the PCRE_INFO_JIT option. A
+       result of 1 means that JIT compilation was successful. A  result  of  0
+       means that JIT support is not available, or the pattern was not studied
+       with PCRE_STUDY_JIT_COMPILE etc., or the JIT compiler was not  able  to
+       handle the pattern.
+
+       Once a pattern has been studied, with or without JIT, it can be used as
+       many times as you like for matching different subject strings.
+
+
+UNSUPPORTED OPTIONS AND PATTERN ITEMS
+
+       The only pcre_exec() options that are supported for JIT  execution  are
+       PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK, PCRE_NO_UTF32_CHECK, PCRE_NOT-
+       BOL,  PCRE_NOTEOL,  PCRE_NOTEMPTY,   PCRE_NOTEMPTY_ATSTART,   PCRE_PAR-
+       TIAL_HARD, and PCRE_PARTIAL_SOFT.
+
+       The  only  unsupported  pattern items are \C (match a single data unit)
+       when running in a UTF mode, and a callout immediately before an  asser-
+       tion condition in a conditional group.
+
+
+RETURN VALUES FROM JIT EXECUTION
+
+       When  a  pattern  is matched using JIT execution, the return values are
+       the same as those given by the interpretive pcre_exec() code, with  the
+       addition  of  one new error code: PCRE_ERROR_JIT_STACKLIMIT. This means
+       that the memory used for the JIT stack was insufficient. See  "Control-
+       ling the JIT stack" below for a discussion of JIT stack usage. For com-
+       patibility with the interpretive pcre_exec() code, no  more  than  two-
+       thirds  of  the ovector argument is used for passing back captured sub-
+       strings.
+
+       The error code PCRE_ERROR_MATCHLIMIT is returned by  the  JIT  code  if
+       searching  a  very large pattern tree goes on for too long, as it is in
+       the same circumstance when JIT is not used, but the details of  exactly
+       what  is  counted are not the same. The PCRE_ERROR_RECURSIONLIMIT error
+       code is never returned by JIT execution.
+
+
+SAVING AND RESTORING COMPILED PATTERNS
+
+       The code that is generated by the  JIT  compiler  is  architecture-spe-
+       cific,  and  is also position dependent. For those reasons it cannot be
+       saved (in a file or database) and restored later like the bytecode  and
+       other  data  of  a compiled pattern. Saving and restoring compiled pat-
+       terns is not something many people do. More detail about this  facility
+       is  given in the pcreprecompile documentation. It should be possible to
+       run pcre_study() on a saved and restored pattern, and thereby  recreate
+       the  JIT  data, but because JIT compilation uses significant resources,
+       it is probably not worth doing this; you might as  well  recompile  the
+       original pattern.
+
+
+CONTROLLING THE JIT STACK
+
+       When the compiled JIT code runs, it needs a block of memory to use as a
+       stack.  By default, it uses 32K on the  machine  stack.  However,  some
+       large   or   complicated  patterns  need  more  than  this.  The  error
+       PCRE_ERROR_JIT_STACKLIMIT is given when  there  is  not  enough  stack.
+       Three  functions  are provided for managing blocks of memory for use as
+       JIT stacks. There is further discussion about the use of JIT stacks  in
+       the section entitled "JIT stack FAQ" below.
+
+       The  pcre_jit_stack_alloc() function creates a JIT stack. Its arguments
+       are a starting size and a maximum size, and it returns a pointer to  an
+       opaque  structure of type pcre_jit_stack, or NULL if there is an error.
+       The pcre_jit_stack_free() function can be used to free a stack that  is
+       no  longer  needed.  (For  the technically minded: the address space is
+       allocated by mmap or VirtualAlloc.)
+
+       JIT uses far less memory for recursion than the interpretive code,  and
+       a  maximum  stack size of 512K to 1M should be more than enough for any
+       pattern.
+
+       The pcre_assign_jit_stack() function specifies  which  stack  JIT  code
+       should use. Its arguments are as follows:
+
+         pcre_extra         *extra
+         pcre_jit_callback  callback
+         void               *data
+
+       The  extra  argument  must  be  the  result  of studying a pattern with
+       PCRE_STUDY_JIT_COMPILE etc. There are three cases for the values of the
+       other two options:
+
+         (1) If callback is NULL and data is NULL, an internal 32K block
+             on the machine stack is used.
+
+         (2) If callback is NULL and data is not NULL, data must be
+             a valid JIT stack, the result of calling pcre_jit_stack_alloc().
+
+         (3) If callback is not NULL, it must point to a function that is
+             called with data as an argument at the start of matching, in
+             order to set up a JIT stack. If the return from the callback
+             function is NULL, the internal 32K stack is used; otherwise the
+             return value must be a valid JIT stack, the result of calling
+             pcre_jit_stack_alloc().
+
+       A  callback function is obeyed whenever JIT code is about to be run; it
+       is not obeyed when pcre_exec() is called with options that  are  incom-
+       patible for JIT execution. A callback function can therefore be used to
+       determine whether a match operation was  executed  by  JIT  or  by  the
+       interpreter.
+
+       You may safely use the same JIT stack for more than one pattern (either
+       by assigning directly or by callback), as long as the patterns are  all
+       matched  sequentially in the same thread. In a multithread application,
+       if you do not specify a JIT stack, or if you assign or pass  back  NULL
+       from  a  callback, that is thread-safe, because each thread has its own
+       machine stack. However, if you assign  or  pass  back  a  non-NULL  JIT
+       stack,  this  must  be  a  different  stack for each thread so that the
+       application is thread-safe.
+
+       Strictly speaking, even more is allowed. You can assign the  same  non-
+       NULL  stack  to any number of patterns as long as they are not used for
+       matching by multiple threads at the same time.  For  example,  you  can
+       assign  the same stack to all compiled patterns, and use a global mutex
+       in the callback to wait until the stack is available for use.  However,
+       this is an inefficient solution, and not recommended.
+
+       This  is a suggestion for how a multithreaded program that needs to set
+       up non-default JIT stacks might operate:
+
+         During thread initalization
+           thread_local_var = pcre_jit_stack_alloc(...)
+
+         During thread exit
+           pcre_jit_stack_free(thread_local_var)
+
+         Use a one-line callback function
+           return thread_local_var
+
+       All the functions described in this section do nothing if  JIT  is  not
+       available,  and  pcre_assign_jit_stack()  does nothing unless the extra
+       argument is non-NULL and points to  a  pcre_extra  block  that  is  the
+       result of a successful study with PCRE_STUDY_JIT_COMPILE etc.
+
+
+JIT STACK FAQ
+
+       (1) Why do we need JIT stacks?
+
+       PCRE  (and JIT) is a recursive, depth-first engine, so it needs a stack
+       where the local data of the current node is pushed before checking  its
+       child nodes.  Allocating real machine stack on some platforms is diffi-
+       cult. For example, the stack chain needs to be updated every time if we
+       extend  the  stack  on  PowerPC.  Although it is possible, its updating
+       time overhead decreases performance. So we do the recursion in memory.
+
+       (2) Why don't we simply allocate blocks of memory with malloc()?
+
+       Modern operating systems have a  nice  feature:  they  can  reserve  an
+       address space instead of allocating memory. We can safely allocate mem-
+       ory pages inside this address space, so the stack  could  grow  without
+       moving memory data (this is important because of pointers). Thus we can
+       allocate 1M address space, and use only a single memory  page  (usually
+       4K)  if  that is enough. However, we can still grow up to 1M anytime if
+       needed.
+
+       (3) Who "owns" a JIT stack?
+
+       The owner of the stack is the user program, not the JIT studied pattern
+       or  anything else. The user program must ensure that if a stack is used
+       by pcre_exec(), (that is, it is assigned to the pattern currently  run-
+       ning), that stack must not be used by any other threads (to avoid over-
+       writing the same memory area). The best practice for multithreaded pro-
+       grams  is  to  allocate  a stack for each thread, and return this stack
+       through the JIT callback function.
+
+       (4) When should a JIT stack be freed?
+
+       You can free a JIT stack at any time, as long as it will not be used by
+       pcre_exec()  again.  When  you  assign  the  stack to a pattern, only a
+       pointer is set. There is no reference counting or any other magic.  You
+       can  free  the  patterns  and stacks in any order, anytime. Just do not
+       call pcre_exec() with a pattern pointing to an already freed stack,  as
+       that  will cause SEGFAULT. (Also, do not free a stack currently used by
+       pcre_exec() in another thread). You can also replace the  stack  for  a
+       pattern  at  any  time.  You  can  even  free the previous stack before
+       assigning a replacement.
+
+       (5) Should I allocate/free a  stack  every  time  before/after  calling
+       pcre_exec()?
+
+       No,  because  this  is  too  costly in terms of resources. However, you
+       could implement some clever idea which release the stack if it  is  not
+       used  in  let's  say  two minutes. The JIT callback can help to achieve
+       this without keeping a list of the currently JIT studied patterns.
+
+       (6) OK, the stack is for long term memory allocation. But what  happens
+       if  a pattern causes stack overflow with a stack of 1M? Is that 1M kept
+       until the stack is freed?
+
+       Especially on embedded sytems, it might be a good idea to release  mem-
+       ory  sometimes  without  freeing the stack. There is no API for this at
+       the moment.  Probably a function call which returns with the  currently
+       allocated  memory for any stack and another which allows releasing mem-
+       ory (shrinking the stack) would be a good idea if someone needs this.
+
+       (7) This is too much of a headache. Isn't there any better solution for
+       JIT stack handling?
+
+       No,  thanks to Windows. If POSIX threads were used everywhere, we could
+       throw out this complicated API.
+
+
+EXAMPLE CODE
+
+       This is a single-threaded example that specifies a  JIT  stack  without
+       using a callback.
+
+         int rc;
+         int ovector[30];
+         pcre *re;
+         pcre_extra *extra;
+         pcre_jit_stack *jit_stack;
+
+         re = pcre_compile(pattern, 0, &error, &erroffset, NULL);
+         /* Check for errors */
+         extra = pcre_study(re, PCRE_STUDY_JIT_COMPILE, &error);
+         jit_stack = pcre_jit_stack_alloc(32*1024, 512*1024);
+         /* Check for error (NULL) */
+         pcre_assign_jit_stack(extra, NULL, jit_stack);
+         rc = pcre_exec(re, extra, subject, length, 0, 0, ovector, 30);
+         /* Check results */
+         pcre_free(re);
+         pcre_free_study(extra);
+         pcre_jit_stack_free(jit_stack);
+
+
+JIT FAST PATH API
+
+       Because  the  API  described  above falls back to interpreted execution
+       when JIT is not available, it is convenient for programs that are writ-
+       ten  for  general  use  in  many environments. However, calling JIT via
+       pcre_exec() does have a performance impact. Programs that  are  written
+       for  use  where  JIT  is known to be available, and which need the best
+       possible performance, can instead use a "fast path"  API  to  call  JIT
+       execution  directly  instead of calling pcre_exec() (obviously only for
+       patterns that have been successfully studied by JIT).
+
+       The fast path function is called pcre_jit_exec(), and it takes  exactly
+       the  same  arguments  as pcre_exec(), plus one additional argument that
+       must point to a JIT stack. The JIT stack arrangements  described  above
+       do not apply. The return values are the same as for pcre_exec().
+
+       When  you  call  pcre_exec(), as well as testing for invalid options, a
+       number of other sanity checks are performed on the arguments. For exam-
+       ple,  if  the  subject  pointer  is NULL, or its length is negative, an
+       immediate error is given. Also, unless PCRE_NO_UTF[8|16|32] is  set,  a
+       UTF  subject  string is tested for validity. In the interests of speed,
+       these checks do not happen on the JIT fast path, and if invalid data is
+       passed, the result is undefined.
+
+       Bypassing  the  sanity  checks  and  the  pcre_exec() wrapping can give
+       speedups of more than 10%.
+
+
+SEE ALSO
+
+       pcreapi(3)
+
+
+AUTHOR
+
+       Philip Hazel (FAQ by Zoltan Herczeg)
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 17 March 2013
+       Copyright (c) 1997-2013 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCREPARTIAL(3)             Library Functions Manual             PCREPARTIAL(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+PARTIAL MATCHING IN PCRE
+
+       In normal use of PCRE, if the subject string that is passed to a match-
+       ing function matches as far as it goes, but is too short to  match  the
+       entire pattern, PCRE_ERROR_NOMATCH is returned. There are circumstances
+       where it might be helpful to distinguish this case from other cases  in
+       which there is no match.
+
+       Consider, for example, an application where a human is required to type
+       in data for a field with specific formatting requirements.  An  example
+       might be a date in the form ddmmmyy, defined by this pattern:
+
+         ^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$
+
+       If the application sees the user's keystrokes one by one, and can check
+       that what has been typed so far is potentially valid,  it  is  able  to
+       raise  an  error  as  soon  as  a  mistake  is made, by beeping and not
+       reflecting the character that has been typed, for example. This immedi-
+       ate  feedback is likely to be a better user interface than a check that
+       is delayed until the entire string has been entered.  Partial  matching
+       can  also be useful when the subject string is very long and is not all
+       available at once.
+
+       PCRE supports partial matching by means of  the  PCRE_PARTIAL_SOFT  and
+       PCRE_PARTIAL_HARD  options,  which  can  be set when calling any of the
+       matching functions. For backwards compatibility, PCRE_PARTIAL is a syn-
+       onym  for  PCRE_PARTIAL_SOFT.  The essential difference between the two
+       options is whether or not a partial match is preferred to  an  alterna-
+       tive complete match, though the details differ between the two types of
+       matching function. If both options  are  set,  PCRE_PARTIAL_HARD  takes
+       precedence.
+
+       If  you  want to use partial matching with just-in-time optimized code,
+       you must call pcre_study(), pcre16_study() or  pcre32_study() with  one
+       or both of these options:
+
+         PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+         PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+
+       PCRE_STUDY_JIT_COMPILE  should also be set if you are going to run non-
+       partial matches on the same pattern. If the appropriate JIT study  mode
+       has not been set for a match, the interpretive matching code is used.
+
+       Setting a partial matching option disables two of PCRE's standard opti-
+       mizations. PCRE remembers the last literal data unit in a pattern,  and
+       abandons  matching  immediately  if  it  is  not present in the subject
+       string. This optimization cannot be used  for  a  subject  string  that
+       might  match only partially. If the pattern was studied, PCRE knows the
+       minimum length of a matching string, and does not  bother  to  run  the
+       matching  function  on  shorter strings. This optimization is also dis-
+       abled for partial matching.
+
+
+PARTIAL MATCHING USING pcre_exec() OR pcre[16|32]_exec()
+
+       A  partial   match   occurs   during   a   call   to   pcre_exec()   or
+       pcre[16|32]_exec()  when  the end of the subject string is reached suc-
+       cessfully, but matching cannot continue  because  more  characters  are
+       needed.   However, at least one character in the subject must have been
+       inspected. This character need not  form  part  of  the  final  matched
+       string;  lookbehind  assertions and the \K escape sequence provide ways
+       of inspecting characters before the start of a matched  substring.  The
+       requirement  for  inspecting  at  least one character exists because an
+       empty string can always be matched; without such  a  restriction  there
+       would  always  be  a partial match of an empty string at the end of the
+       subject.
+
+       If there are at least two slots in the offsets vector  when  a  partial
+       match  is returned, the first slot is set to the offset of the earliest
+       character that was inspected. For convenience, the second offset points
+       to the end of the subject so that a substring can easily be identified.
+       If there are at least three slots in the offsets vector, the third slot
+       is set to the offset of the character where matching started.
+
+       For the majority of patterns, the contents of the first and third slots
+       will be the same. However, for patterns that contain lookbehind  asser-
+       tions, or begin with \b or \B, characters before the one where matching
+       started may have been inspected while carrying out the match. For exam-
+       ple, consider this pattern:
+
+         /(?<=abc)123/
+
+       This pattern matches "123", but only if it is preceded by "abc". If the
+       subject string is "xyzabc12", the first two  offsets  after  a  partial
+       match  are for the substring "abc12", because all these characters were
+       inspected. However, the third offset is set to 6, because that  is  the
+       offset where matching began.
+
+       What happens when a partial match is identified depends on which of the
+       two partial matching options are set.
+
+   PCRE_PARTIAL_SOFT WITH pcre_exec() OR pcre[16|32]_exec()
+
+       If PCRE_PARTIAL_SOFT is  set  when  pcre_exec()  or  pcre[16|32]_exec()
+       identifies a partial match, the partial match is remembered, but match-
+       ing continues as normal, and other  alternatives  in  the  pattern  are
+       tried.  If  no  complete  match  can  be  found,  PCRE_ERROR_PARTIAL is
+       returned instead of PCRE_ERROR_NOMATCH.
+
+       This option is "soft" because it prefers a complete match over  a  par-
+       tial  match.   All the various matching items in a pattern behave as if
+       the subject string is potentially complete. For example, \z, \Z, and  $
+       match  at  the end of the subject, as normal, and for \b and \B the end
+       of the subject is treated as a non-alphanumeric.
+
+       If there is more than one partial match, the first one that  was  found
+       provides the data that is returned. Consider this pattern:
+
+         /123\w+X|dogY/
+
+       If  this is matched against the subject string "abc123dog", both alter-
+       natives fail to match, but the end of the  subject  is  reached  during
+       matching,  so  PCRE_ERROR_PARTIAL is returned. The offsets are set to 3
+       and 9, identifying "123dog" as the first partial match that was  found.
+       (In  this  example, there are two partial matches, because "dog" on its
+       own partially matches the second alternative.)
+
+   PCRE_PARTIAL_HARD WITH pcre_exec() OR pcre[16|32]_exec()
+
+       If PCRE_PARTIAL_HARD is  set  for  pcre_exec()  or  pcre[16|32]_exec(),
+       PCRE_ERROR_PARTIAL  is  returned  as  soon as a partial match is found,
+       without continuing to search for possible complete matches. This option
+       is "hard" because it prefers an earlier partial match over a later com-
+       plete match. For this reason, the assumption is made that  the  end  of
+       the  supplied  subject  string may not be the true end of the available
+       data, and so, if \z, \Z, \b, \B, or $ are encountered at the end of the
+       subject,  the  result is PCRE_ERROR_PARTIAL, provided that at least one
+       character in the subject has been inspected.
+
+       Setting PCRE_PARTIAL_HARD also affects the way UTF-8 and UTF-16 subject
+       strings  are checked for validity. Normally, an invalid sequence causes
+       the error PCRE_ERROR_BADUTF8 or PCRE_ERROR_BADUTF16.  However,  in  the
+       special  case  of  a  truncated  character  at  the end of the subject,
+       PCRE_ERROR_SHORTUTF8  or   PCRE_ERROR_SHORTUTF16   is   returned   when
+       PCRE_PARTIAL_HARD is set.
+
+   Comparing hard and soft partial matching
+
+       The  difference  between the two partial matching options can be illus-
+       trated by a pattern such as:
+
+         /dog(sbody)?/
+
+       This matches either "dog" or "dogsbody", greedily (that is, it  prefers
+       the  longer  string  if  possible). If it is matched against the string
+       "dog" with PCRE_PARTIAL_SOFT, it yields a  complete  match  for  "dog".
+       However, if PCRE_PARTIAL_HARD is set, the result is PCRE_ERROR_PARTIAL.
+       On the other hand, if the pattern is made ungreedy the result  is  dif-
+       ferent:
+
+         /dog(sbody)??/
+
+       In  this  case  the  result  is always a complete match because that is
+       found first, and matching never  continues  after  finding  a  complete
+       match. It might be easier to follow this explanation by thinking of the
+       two patterns like this:
+
+         /dog(sbody)?/    is the same as  /dogsbody|dog/
+         /dog(sbody)??/   is the same as  /dog|dogsbody/
+
+       The second pattern will never match "dogsbody", because it will  always
+       find the shorter match first.
+
+
+PARTIAL MATCHING USING pcre_dfa_exec() OR pcre[16|32]_dfa_exec()
+
+       The DFA functions move along the subject string character by character,
+       without backtracking, searching for  all  possible  matches  simultane-
+       ously.  If the end of the subject is reached before the end of the pat-
+       tern, there is the possibility of a partial match, again provided  that
+       at least one character has been inspected.
+
+       When  PCRE_PARTIAL_SOFT  is set, PCRE_ERROR_PARTIAL is returned only if
+       there have been no complete matches. Otherwise,  the  complete  matches
+       are  returned.   However,  if PCRE_PARTIAL_HARD is set, a partial match
+       takes precedence over any complete matches. The portion of  the  string
+       that  was  inspected when the longest partial match was found is set as
+       the first matching string, provided there are at least two slots in the
+       offsets vector.
+
+       Because  the  DFA functions always search for all possible matches, and
+       there is no difference between greedy and  ungreedy  repetition,  their
+       behaviour  is  different  from  the  standard  functions when PCRE_PAR-
+       TIAL_HARD is  set.  Consider  the  string  "dog"  matched  against  the
+       ungreedy pattern shown above:
+
+         /dog(sbody)??/
+
+       Whereas  the  standard functions stop as soon as they find the complete
+       match for "dog", the DFA functions also  find  the  partial  match  for
+       "dogsbody", and so return that when PCRE_PARTIAL_HARD is set.
+
+
+PARTIAL MATCHING AND WORD BOUNDARIES
+
+       If  a  pattern ends with one of sequences \b or \B, which test for word
+       boundaries, partial matching with PCRE_PARTIAL_SOFT can  give  counter-
+       intuitive results. Consider this pattern:
+
+         /\bcat\b/
+
+       This matches "cat", provided there is a word boundary at either end. If
+       the subject string is "the cat", the comparison of the final "t" with a
+       following  character  cannot  take  place, so a partial match is found.
+       However, normal matching carries on, and \b matches at the end  of  the
+       subject  when  the  last  character is a letter, so a complete match is
+       found.  The  result,  therefore,  is  not   PCRE_ERROR_PARTIAL.   Using
+       PCRE_PARTIAL_HARD  in  this case does yield PCRE_ERROR_PARTIAL, because
+       then the partial match takes precedence.
+
+
+FORMERLY RESTRICTED PATTERNS
+
+       For releases of PCRE prior to 8.00, because of the way certain internal
+       optimizations   were  implemented  in  the  pcre_exec()  function,  the
+       PCRE_PARTIAL option (predecessor of  PCRE_PARTIAL_SOFT)  could  not  be
+       used  with all patterns. From release 8.00 onwards, the restrictions no
+       longer apply, and partial matching with can be requested for  any  pat-
+       tern.
+
+       Items that were formerly restricted were repeated single characters and
+       repeated metasequences. If PCRE_PARTIAL was set for a pattern that  did
+       not  conform  to  the restrictions, pcre_exec() returned the error code
+       PCRE_ERROR_BADPARTIAL (-13). This error code is no longer in  use.  The
+       PCRE_INFO_OKPARTIAL  call  to pcre_fullinfo() to find out if a compiled
+       pattern can be used for partial matching now always returns 1.
+
+
+EXAMPLE OF PARTIAL MATCHING USING PCRETEST
+
+       If the escape sequence \P is present  in  a  pcretest  data  line,  the
+       PCRE_PARTIAL_SOFT  option  is  used  for  the  match.  Here is a run of
+       pcretest that uses the date example quoted above:
+
+           re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
+         data> 25jun04\P
+          0: 25jun04
+          1: jun
+         data> 25dec3\P
+         Partial match: 23dec3
+         data> 3ju\P
+         Partial match: 3ju
+         data> 3juj\P
+         No match
+         data> j\P
+         No match
+
+       The first data string is matched  completely,  so  pcretest  shows  the
+       matched  substrings.  The  remaining four strings do not match the com-
+       plete pattern, but the first two are partial matches. Similar output is
+       obtained if DFA matching is used.
+
+       If  the escape sequence \P is present more than once in a pcretest data
+       line, the PCRE_PARTIAL_HARD option is set for the match.
+
+
+MULTI-SEGMENT MATCHING WITH pcre_dfa_exec() OR pcre[16|32]_dfa_exec()
+
+       When a partial match has been found using a DFA matching  function,  it
+       is  possible to continue the match by providing additional subject data
+       and calling the function again with the same compiled  regular  expres-
+       sion,  this time setting the PCRE_DFA_RESTART option. You must pass the
+       same working space as before, because this is where details of the pre-
+       vious  partial  match  are  stored.  Here is an example using pcretest,
+       using the \R escape sequence to set  the  PCRE_DFA_RESTART  option  (\D
+       specifies the use of the DFA matching function):
+
+           re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
+         data> 23ja\P\D
+         Partial match: 23ja
+         data> n05\R\D
+          0: n05
+
+       The  first  call has "23ja" as the subject, and requests partial match-
+       ing; the second call  has  "n05"  as  the  subject  for  the  continued
+       (restarted)  match.   Notice  that when the match is complete, only the
+       last part is shown; PCRE does  not  retain  the  previously  partially-
+       matched  string. It is up to the calling program to do that if it needs
+       to.
+
+       That means that, for an unanchored pattern, if a continued match fails,
+       it  is  not  possible  to  try  again at a new starting point. All this
+       facility is capable of doing is  continuing  with  the  previous  match
+       attempt.  In  the previous example, if the second set of data is "ug23"
+       the result is no match, even though there would be a match for  "aug23"
+       if  the entire string were given at once. Depending on the application,
+       this may or may not be what you want.  The only way to allow for start-
+       ing  again  at  the next character is to retain the matched part of the
+       subject and try a new complete match.
+
+       You can set the PCRE_PARTIAL_SOFT  or  PCRE_PARTIAL_HARD  options  with
+       PCRE_DFA_RESTART  to  continue partial matching over multiple segments.
+       This facility can be used to pass very long subject strings to the  DFA
+       matching functions.
+
+
+MULTI-SEGMENT MATCHING WITH pcre_exec() OR pcre[16|32]_exec()
+
+       From  release 8.00, the standard matching functions can also be used to
+       do multi-segment matching. Unlike the DFA functions, it is not possible
+       to  restart the previous match with a new segment of data. Instead, new
+       data must be added to the previous subject string, and the entire match
+       re-run,  starting from the point where the partial match occurred. Ear-
+       lier data can be discarded.
+
+       It is best to use PCRE_PARTIAL_HARD in this situation, because it  does
+       not  treat the end of a segment as the end of the subject when matching
+       \z, \Z, \b, \B, and $. Consider  an  unanchored  pattern  that  matches
+       dates:
+
+           re> /\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d/
+         data> The date is 23ja\P\P
+         Partial match: 23ja
+
+       At  this stage, an application could discard the text preceding "23ja",
+       add on text from the next  segment,  and  call  the  matching  function
+       again.  Unlike  the  DFA matching functions, the entire matching string
+       must always be available, and the complete matching process occurs  for
+       each call, so more memory and more processing time is needed.
+
+       Note:  If  the pattern contains lookbehind assertions, or \K, or starts
+       with \b or \B, the string that is returned for a partial match includes
+       characters  that precede the start of what would be returned for a com-
+       plete match, because it contains all the characters that were inspected
+       during the partial match.
+
+
+ISSUES WITH MULTI-SEGMENT MATCHING
+
+       Certain types of pattern may give problems with multi-segment matching,
+       whichever matching function is used.
+
+       1. If the pattern contains a test for the beginning of a line, you need
+       to  pass  the  PCRE_NOTBOL  option when the subject string for any call
+       does start at the beginning of a line.  There  is  also  a  PCRE_NOTEOL
+       option, but in practice when doing multi-segment matching you should be
+       using PCRE_PARTIAL_HARD, which includes the effect of PCRE_NOTEOL.
+
+       2. Lookbehind assertions that have already been obeyed are catered  for
+       in the offsets that are returned for a partial match. However a lookbe-
+       hind assertion later in the pattern could require even earlier  charac-
+       ters   to  be  inspected.  You  can  handle  this  case  by  using  the
+       PCRE_INFO_MAXLOOKBEHIND    option    of    the    pcre_fullinfo()    or
+       pcre[16|32]_fullinfo()  functions  to  obtain the length of the longest
+       lookbehind in the pattern. This length  is  given  in  characters,  not
+       bytes.  If  you  always retain at least that many characters before the
+       partially matched string, all should be  well.  (Of  course,  near  the
+       start of the subject, fewer characters may be present; in that case all
+       characters should be retained.)
+
+       From release 8.33, there is a more accurate way of deciding which char-
+       acters  to  retain.  Instead  of  subtracting the length of the longest
+       lookbehind from the  earliest  inspected  character  (offsets[0]),  the
+       match  start  position  (offsets[2]) should be used, and the next match
+       attempt started at the offsets[2] character by setting the  startoffset
+       argument of pcre_exec() or pcre_dfa_exec().
+
+       For  example, if the pattern "(?<=123)abc" is partially matched against
+       the string "xx123a", the three offset values returned are 2, 6, and  5.
+       This  indicates  that  the  matching  process that gave a partial match
+       started at offset 5, but the characters "123a" were all inspected.  The
+       maximum  lookbehind  for  that pattern is 3, so taking that away from 5
+       shows that we need only keep "123a", and the next match attempt can  be
+       started at offset 3 (that is, at "a") when further characters have been
+       added. When the match start is not the  earliest  inspected  character,
+       pcretest shows it explicitly:
+
+           re> "(?<=123)abc"
+         data> xx123a\P\P
+         Partial match at offset 5: 123a
+
+       3.  Because a partial match must always contain at least one character,
+       what might be considered a partial match of an  empty  string  actually
+       gives a "no match" result. For example:
+
+           re> /c(?<=abc)x/
+         data> ab\P
+         No match
+
+       If the next segment begins "cx", a match should be found, but this will
+       only happen if characters from the previous segment are  retained.  For
+       this  reason,  a  "no  match"  result should be interpreted as "partial
+       match of an empty string" when the pattern contains lookbehinds.
+
+       4. Matching a subject string that is split into multiple  segments  may
+       not  always produce exactly the same result as matching over one single
+       long string, especially when PCRE_PARTIAL_SOFT  is  used.  The  section
+       "Partial  Matching  and  Word Boundaries" above describes an issue that
+       arises if the pattern ends with \b or \B. Another  kind  of  difference
+       may  occur when there are multiple matching possibilities, because (for
+       PCRE_PARTIAL_SOFT) a partial match result is given only when there  are
+       no completed matches. This means that as soon as the shortest match has
+       been found, continuation to a new subject segment is no  longer  possi-
+       ble. Consider again this pcretest example:
+
+           re> /dog(sbody)?/
+         data> dogsb\P
+          0: dog
+         data> do\P\D
+         Partial match: do
+         data> gsb\R\P\D
+          0: g
+         data> dogsbody\D
+          0: dogsbody
+          1: dog
+
+       The  first  data  line passes the string "dogsb" to a standard matching
+       function, setting the PCRE_PARTIAL_SOFT option. Although the string  is
+       a  partial  match for "dogsbody", the result is not PCRE_ERROR_PARTIAL,
+       because the shorter string "dog" is a complete match.  Similarly,  when
+       the  subject  is  presented to a DFA matching function in several parts
+       ("do" and "gsb" being the first two) the match  stops  when  "dog"  has
+       been  found, and it is not possible to continue.  On the other hand, if
+       "dogsbody" is presented as a single string,  a  DFA  matching  function
+       finds both matches.
+
+       Because  of  these  problems,  it is best to use PCRE_PARTIAL_HARD when
+       matching multi-segment data. The example  above  then  behaves  differ-
+       ently:
+
+           re> /dog(sbody)?/
+         data> dogsb\P\P
+         Partial match: dogsb
+         data> do\P\D
+         Partial match: do
+         data> gsb\R\P\P\D
+         Partial match: gsb
+
+       5. Patterns that contain alternatives at the top level which do not all
+       start with the  same  pattern  item  may  not  work  as  expected  when
+       PCRE_DFA_RESTART is used. For example, consider this pattern:
+
+         1234|3789
+
+       If  the  first  part of the subject is "ABC123", a partial match of the
+       first alternative is found at offset 3. There is no partial  match  for
+       the second alternative, because such a match does not start at the same
+       point in the subject string. Attempting to  continue  with  the  string
+       "7890"  does  not  yield  a  match because only those alternatives that
+       match at one point in the subject are remembered.  The  problem  arises
+       because  the  start  of the second alternative matches within the first
+       alternative. There is no problem with  anchored  patterns  or  patterns
+       such as:
+
+         1234|ABCD
+
+       where  no  string can be a partial match for both alternatives. This is
+       not a problem if a standard matching  function  is  used,  because  the
+       entire match has to be rerun each time:
+
+           re> /1234|3789/
+         data> ABC123\P\P
+         Partial match: 123
+         data> 1237890
+          0: 3789
+
+       Of course, instead of using PCRE_DFA_RESTART, the same technique of re-
+       running the entire match can also be used with the DFA  matching  func-
+       tions.  Another  possibility  is to work with two buffers. If a partial
+       match at offset n in the first buffer is followed by  "no  match"  when
+       PCRE_DFA_RESTART  is  used on the second buffer, you can then try a new
+       match starting at offset n+1 in the first buffer.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 02 July 2013
+       Copyright (c) 1997-2013 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCREPRECOMPILE(3)          Library Functions Manual          PCREPRECOMPILE(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+SAVING AND RE-USING PRECOMPILED PCRE PATTERNS
+
+       If  you  are running an application that uses a large number of regular
+       expression patterns, it may be useful to store them  in  a  precompiled
+       form  instead  of  having to compile them every time the application is
+       run.  If you are not  using  any  private  character  tables  (see  the
+       pcre_maketables()  documentation),  this is relatively straightforward.
+       If you are using private tables, it is a little bit  more  complicated.
+       However,  if you are using the just-in-time optimization feature, it is
+       not possible to save and reload the JIT data.
+
+       If you save compiled patterns to a file, you can copy them to a differ-
+       ent host and run them there. If the two hosts have different endianness
+       (byte    order),    you     should     run     the     pcre[16|32]_pat-
+       tern_to_host_byte_order()  function  on  the  new host before trying to
+       match the pattern. The matching functions return  PCRE_ERROR_BADENDIAN-
+       NESS if they detect a pattern with the wrong endianness.
+
+       Compiling  regular  expressions with one version of PCRE for use with a
+       different version is not guaranteed to work and may cause crashes,  and
+       saving  and  restoring  a  compiled  pattern loses any JIT optimization
+       data.
+
+
+SAVING A COMPILED PATTERN
+
+       The value returned by pcre[16|32]_compile() points to a single block of
+       memory  that  holds  the  compiled pattern and associated data. You can
+       find   the   length   of   this   block    in    bytes    by    calling
+       pcre[16|32]_fullinfo() with an argument of PCRE_INFO_SIZE. You can then
+       save the data in any appropriate manner. Here is sample  code  for  the
+       8-bit  library  that  compiles  a  pattern  and writes it to a file. It
+       assumes that the variable fd refers to a file that is open for output:
+
+         int erroroffset, rc, size;
+         char *error;
+         pcre *re;
+
+         re = pcre_compile("my pattern", 0, &error, &erroroffset, NULL);
+         if (re == NULL) { ... handle errors ... }
+         rc = pcre_fullinfo(re, NULL, PCRE_INFO_SIZE, &size);
+         if (rc < 0) { ... handle errors ... }
+         rc = fwrite(re, 1, size, fd);
+         if (rc != size) { ... handle errors ... }
+
+       In this example, the bytes  that  comprise  the  compiled  pattern  are
+       copied  exactly.  Note that this is binary data that may contain any of
+       the 256 possible byte  values.  On  systems  that  make  a  distinction
+       between binary and non-binary data, be sure that the file is opened for
+       binary output.
+
+       If you want to write more than one pattern to a file, you will have  to
+       devise  a  way of separating them. For binary data, preceding each pat-
+       tern with its length is probably  the  most  straightforward  approach.
+       Another  possibility is to write out the data in hexadecimal instead of
+       binary, one pattern to a line.
+
+       Saving compiled patterns in a file is only one possible way of  storing
+       them  for later use. They could equally well be saved in a database, or
+       in the memory of some daemon process that passes them  via  sockets  to
+       the processes that want them.
+
+       If the pattern has been studied, it is also possible to save the normal
+       study data in a similar way to the compiled pattern itself. However, if
+       the PCRE_STUDY_JIT_COMPILE was used, the just-in-time data that is cre-
+       ated cannot be saved because it is too dependent on the  current  envi-
+       ronment.    When    studying    generates    additional    information,
+       pcre[16|32]_study() returns  a  pointer  to  a  pcre[16|32]_extra  data
+       block.  Its  format  is defined in the section on matching a pattern in
+       the pcreapi documentation. The study_data field points  to  the  binary
+       study  data,  and this is what you must save (not the pcre[16|32]_extra
+       block itself). The length of the study data can be obtained by  calling
+       pcre[16|32]_fullinfo()  with an argument of PCRE_INFO_STUDYSIZE. Remem-
+       ber to check that  pcre[16|32]_study()  did  return  a  non-NULL  value
+       before trying to save the study data.
+
+
+RE-USING A PRECOMPILED PATTERN
+
+       Re-using  a  precompiled pattern is straightforward. Having reloaded it
+       into main memory,  called  pcre[16|32]_pattern_to_host_byte_order()  if
+       necessary,    you   pass   its   pointer   to   pcre[16|32]_exec()   or
+       pcre[16|32]_dfa_exec() in the usual way.
+
+       However, if you passed a pointer to custom character  tables  when  the
+       pattern  was compiled (the tableptr argument of pcre[16|32]_compile()),
+       you  must  now  pass  a  similar  pointer  to   pcre[16|32]_exec()   or
+       pcre[16|32]_dfa_exec(),  because the value saved with the compiled pat-
+       tern will obviously be nonsense. A field in a pcre[16|32]_extra() block
+       is  used  to  pass this data, as described in the section on matching a
+       pattern in the pcreapi documentation.
+
+       Warning: The tables that pcre_exec() and pcre_dfa_exec()  use  must  be
+       the same as those that were used when the pattern was compiled. If this
+       is not the case, the behaviour is undefined.
+
+       If you did not provide custom character tables  when  the  pattern  was
+       compiled, the pointer in the compiled pattern is NULL, which causes the
+       matching functions to use PCRE's internal tables. Thus, you do not need
+       to take any special action at run time in this case.
+
+       If  you  saved study data with the compiled pattern, you need to create
+       your own pcre[16|32]_extra data block and set the study_data  field  to
+       point   to   the   reloaded   study   data.   You  must  also  set  the
+       PCRE_EXTRA_STUDY_DATA bit in the flags field  to  indicate  that  study
+       data  is present. Then pass the pcre[16|32]_extra block to the matching
+       function in the usual way. If the pattern was studied for  just-in-time
+       optimization,  that  data  cannot  be  saved,  and  so  is  lost  by  a
+       save/restore cycle.
+
+
+COMPATIBILITY WITH DIFFERENT PCRE RELEASES
+
+       In general, it is safest to  recompile  all  saved  patterns  when  you
+       update  to  a new PCRE release, though not all updates actually require
+       this.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 12 November 2013
+       Copyright (c) 1997-2013 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCREPERFORM(3)             Library Functions Manual             PCREPERFORM(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+PCRE PERFORMANCE
+
+       Two  aspects  of performance are discussed below: memory usage and pro-
+       cessing time. The way you express your pattern as a regular  expression
+       can affect both of them.
+
+
+COMPILED PATTERN MEMORY USAGE
+
+       Patterns  are compiled by PCRE into a reasonably efficient interpretive
+       code, so that most simple patterns do not  use  much  memory.  However,
+       there  is  one case where the memory usage of a compiled pattern can be
+       unexpectedly large. If a parenthesized subpattern has a quantifier with
+       a minimum greater than 1 and/or a limited maximum, the whole subpattern
+       is repeated in the compiled code. For example, the pattern
+
+         (abc|def){2,4}
+
+       is compiled as if it were
+
+         (abc|def)(abc|def)((abc|def)(abc|def)?)?
+
+       (Technical aside: It is done this way so that backtrack  points  within
+       each of the repetitions can be independently maintained.)
+
+       For  regular expressions whose quantifiers use only small numbers, this
+       is not usually a problem. However, if the numbers are large,  and  par-
+       ticularly  if  such repetitions are nested, the memory usage can become
+       an embarrassment. For example, the very simple pattern
+
+         ((ab){1,1000}c){1,3}
+
+       uses 51K bytes when compiled using the 8-bit library. When PCRE is com-
+       piled  with  its  default  internal pointer size of two bytes, the size
+       limit on a compiled pattern is 64K data units, and this is reached with
+       the  above  pattern  if  the outer repetition is increased from 3 to 4.
+       PCRE can be compiled to use larger internal pointers  and  thus  handle
+       larger  compiled patterns, but it is better to try to rewrite your pat-
+       tern to use less memory if you can.
+
+       One way of reducing the memory usage for such patterns is to  make  use
+       of PCRE's "subroutine" facility. Re-writing the above pattern as
+
+         ((ab)(?2){0,999}c)(?1){0,2}
+
+       reduces the memory requirements to 18K, and indeed it remains under 20K
+       even with the outer repetition increased to 100. However, this  pattern
+       is  not  exactly equivalent, because the "subroutine" calls are treated
+       as atomic groups into which there can be no backtracking if there is  a
+       subsequent  matching  failure.  Therefore,  PCRE cannot do this kind of
+       rewriting automatically.  Furthermore, there is a  noticeable  loss  of
+       speed  when executing the modified pattern. Nevertheless, if the atomic
+       grouping is not a problem and the loss of  speed  is  acceptable,  this
+       kind  of  rewriting will allow you to process patterns that PCRE cannot
+       otherwise handle.
+
+
+STACK USAGE AT RUN TIME
+
+       When pcre_exec() or pcre[16|32]_exec() is used  for  matching,  certain
+       kinds  of  pattern  can  cause  it  to use large amounts of the process
+       stack. In some environments the default process stack is  quite  small,
+       and  if it runs out the result is often SIGSEGV. This issue is probably
+       the most frequently raised problem with PCRE.  Rewriting  your  pattern
+       can  often  help.  The  pcrestack documentation discusses this issue in
+       detail.
+
+
+PROCESSING TIME
+
+       Certain items in regular expression patterns are processed  more  effi-
+       ciently than others. It is more efficient to use a character class like
+       [aeiou]  than  a  set  of   single-character   alternatives   such   as
+       (a|e|i|o|u).  In  general,  the simplest construction that provides the
+       required behaviour is usually the most efficient. Jeffrey Friedl's book
+       contains  a  lot  of useful general discussion about optimizing regular
+       expressions for efficient performance. This  document  contains  a  few
+       observations about PCRE.
+
+       Using  Unicode  character  properties  (the  \p, \P, and \X escapes) is
+       slow, because PCRE has to use a multi-stage table  lookup  whenever  it
+       needs  a  character's  property. If you can find an alternative pattern
+       that does not use character properties, it will probably be faster.
+
+       By default, the escape sequences \b, \d, \s,  and  \w,  and  the  POSIX
+       character  classes  such  as  [:alpha:]  do not use Unicode properties,
+       partly for backwards compatibility, and partly for performance reasons.
+       However,  you can set PCRE_UCP if you want Unicode character properties
+       to be used. This can double the matching time for  items  such  as  \d,
+       when matched with a traditional matching function; the performance loss
+       is less with a DFA matching function, and in both cases  there  is  not
+       much difference for \b.
+
+       When  a  pattern  begins  with .* not in parentheses, or in parentheses
+       that are not the subject of a backreference, and the PCRE_DOTALL option
+       is  set, the pattern is implicitly anchored by PCRE, since it can match
+       only at the start of a subject string. However, if PCRE_DOTALL  is  not
+       set,  PCRE  cannot  make this optimization, because the . metacharacter
+       does not then match a newline, and if the subject string contains  new-
+       lines,  the  pattern may match from the character immediately following
+       one of them instead of from the very start. For example, the pattern
+
+         .*second
+
+       matches the subject "first\nand second" (where \n stands for a  newline
+       character),  with the match starting at the seventh character. In order
+       to do this, PCRE has to retry the match starting after every newline in
+       the subject.
+
+       If  you  are using such a pattern with subject strings that do not con-
+       tain newlines, the best performance is obtained by setting PCRE_DOTALL,
+       or  starting  the pattern with ^.* or ^.*? to indicate explicit anchor-
+       ing. That saves PCRE from having to scan along the subject looking  for
+       a newline to restart at.
+
+       Beware  of  patterns  that contain nested indefinite repeats. These can
+       take a long time to run when applied to a string that does  not  match.
+       Consider the pattern fragment
+
+         ^(a+)*
+
+       This  can  match "aaaa" in 16 different ways, and this number increases
+       very rapidly as the string gets longer. (The * repeat can match  0,  1,
+       2,  3, or 4 times, and for each of those cases other than 0 or 4, the +
+       repeats can match different numbers of times.) When  the  remainder  of
+       the pattern is such that the entire match is going to fail, PCRE has in
+       principle to try  every  possible  variation,  and  this  can  take  an
+       extremely long time, even for relatively short strings.
+
+       An optimization catches some of the more simple cases such as
+
+         (a+)*b
+
+       where  a  literal  character  follows. Before embarking on the standard
+       matching procedure, PCRE checks that there is a "b" later in  the  sub-
+       ject  string, and if there is not, it fails the match immediately. How-
+       ever, when there is no following literal this  optimization  cannot  be
+       used. You can see the difference by comparing the behaviour of
+
+         (a+)*\d
+
+       with  the  pattern  above.  The former gives a failure almost instantly
+       when applied to a whole line of  "a"  characters,  whereas  the  latter
+       takes an appreciable time with strings longer than about 20 characters.
+
+       In many cases, the solution to this kind of performance issue is to use
+       an atomic group or a possessive quantifier.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 25 August 2012
+       Copyright (c) 1997-2012 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCREPOSIX(3)               Library Functions Manual               PCREPOSIX(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions.
+
+SYNOPSIS
+
+       #include 
+
+       int regcomp(regex_t *preg, const char *pattern,
+            int cflags);
+
+       int regexec(regex_t *preg, const char *string,
+            size_t nmatch, regmatch_t pmatch[], int eflags);
+            size_t regerror(int errcode, const regex_t *preg,
+            char *errbuf, size_t errbuf_size);
+
+       void regfree(regex_t *preg);
+
+
+DESCRIPTION
+
+       This  set  of functions provides a POSIX-style API for the PCRE regular
+       expression 8-bit library. See the pcreapi documentation for a  descrip-
+       tion  of  PCRE's native API, which contains much additional functional-
+       ity. There is no POSIX-style  wrapper  for  PCRE's  16-bit  and  32-bit
+       library.
+
+       The functions described here are just wrapper functions that ultimately
+       call  the  PCRE  native  API.  Their  prototypes  are  defined  in  the
+       pcreposix.h  header  file,  and  on  Unix systems the library itself is
+       called pcreposix.a, so can be accessed by  adding  -lpcreposix  to  the
+       command  for  linking  an application that uses them. Because the POSIX
+       functions call the native ones, it is also necessary to add -lpcre.
+
+       I have implemented only those POSIX option bits that can be  reasonably
+       mapped  to PCRE native options. In addition, the option REG_EXTENDED is
+       defined with the value zero. This has no  effect,  but  since  programs
+       that  are  written  to  the POSIX interface often use it, this makes it
+       easier to slot in PCRE as a replacement library.  Other  POSIX  options
+       are not even defined.
+
+       There  are also some other options that are not defined by POSIX. These
+       have been added at the request of users who want to make use of certain
+       PCRE-specific features via the POSIX calling interface.
+
+       When  PCRE  is  called  via these functions, it is only the API that is
+       POSIX-like in style. The syntax and semantics of  the  regular  expres-
+       sions  themselves  are  still  those of Perl, subject to the setting of
+       various PCRE options, as described below. "POSIX-like in  style"  means
+       that  the  API  approximates  to  the POSIX definition; it is not fully
+       POSIX-compatible, and in multi-byte encoding  domains  it  is  probably
+       even less compatible.
+
+       The  header for these functions is supplied as pcreposix.h to avoid any
+       potential clash with other POSIX  libraries.  It  can,  of  course,  be
+       renamed or aliased as regex.h, which is the "correct" name. It provides
+       two structure types, regex_t for  compiled  internal  forms,  and  reg-
+       match_t  for  returning  captured substrings. It also defines some con-
+       stants whose names start  with  "REG_";  these  are  used  for  setting
+       options and identifying error codes.
+
+
+COMPILING A PATTERN
+
+       The  function regcomp() is called to compile a pattern into an internal
+       form. The pattern is a C string terminated by a  binary  zero,  and  is
+       passed  in  the  argument  pattern. The preg argument is a pointer to a
+       regex_t structure that is used as a base for storing information  about
+       the compiled regular expression.
+
+       The argument cflags is either zero, or contains one or more of the bits
+       defined by the following macros:
+
+         REG_DOTALL
+
+       The PCRE_DOTALL option is set when the regular expression is passed for
+       compilation to the native function. Note that REG_DOTALL is not part of
+       the POSIX standard.
+
+         REG_ICASE
+
+       The PCRE_CASELESS option is set when the regular expression  is  passed
+       for compilation to the native function.
+
+         REG_NEWLINE
+
+       The  PCRE_MULTILINE option is set when the regular expression is passed
+       for compilation to the native function. Note that this does  not  mimic
+       the  defined  POSIX  behaviour  for REG_NEWLINE (see the following sec-
+       tion).
+
+         REG_NOSUB
+
+       The PCRE_NO_AUTO_CAPTURE option is set when the regular  expression  is
+       passed for compilation to the native function. In addition, when a pat-
+       tern that is compiled with this flag is passed to regexec() for  match-
+       ing,  the  nmatch  and  pmatch  arguments  are ignored, and no captured
+       strings are returned.
+
+         REG_UCP
+
+       The PCRE_UCP option is set when the regular expression  is  passed  for
+       compilation  to  the  native  function. This causes PCRE to use Unicode
+       properties when matchine \d, \w,  etc.,  instead  of  just  recognizing
+       ASCII values. Note that REG_UTF8 is not part of the POSIX standard.
+
+         REG_UNGREEDY
+
+       The  PCRE_UNGREEDY  option is set when the regular expression is passed
+       for compilation to the native function. Note that REG_UNGREEDY  is  not
+       part of the POSIX standard.
+
+         REG_UTF8
+
+       The  PCRE_UTF8  option is set when the regular expression is passed for
+       compilation to the native function. This causes the pattern itself  and
+       all  data  strings used for matching it to be treated as UTF-8 strings.
+       Note that REG_UTF8 is not part of the POSIX standard.
+
+       In the absence of these flags, no options  are  passed  to  the  native
+       function.   This  means  the  the  regex  is compiled with PCRE default
+       semantics. In particular, the way it handles newline characters in  the
+       subject  string  is  the Perl way, not the POSIX way. Note that setting
+       PCRE_MULTILINE has only some of the effects specified for  REG_NEWLINE.
+       It  does not affect the way newlines are matched by . (they are not) or
+       by a negative class such as [^a] (they are).
+
+       The yield of regcomp() is zero on success, and non-zero otherwise.  The
+       preg structure is filled in on success, and one member of the structure
+       is public: re_nsub contains the number of capturing subpatterns in  the
+       regular expression. Various error codes are defined in the header file.
+
+       NOTE:  If  the  yield of regcomp() is non-zero, you must not attempt to
+       use the contents of the preg structure. If, for example, you pass it to
+       regexec(), the result is undefined and your program is likely to crash.
+
+
+MATCHING NEWLINE CHARACTERS
+
+       This area is not simple, because POSIX and Perl take different views of
+       things.  It is not possible to get PCRE to obey  POSIX  semantics,  but
+       then  PCRE was never intended to be a POSIX engine. The following table
+       lists the different possibilities for matching  newline  characters  in
+       PCRE:
+
+                                 Default   Change with
+
+         . matches newline          no     PCRE_DOTALL
+         newline matches [^a]       yes    not changeable
+         $ matches \n at end        yes    PCRE_DOLLARENDONLY
+         $ matches \n in middle     no     PCRE_MULTILINE
+         ^ matches \n in middle     no     PCRE_MULTILINE
+
+       This is the equivalent table for POSIX:
+
+                                 Default   Change with
+
+         . matches newline          yes    REG_NEWLINE
+         newline matches [^a]       yes    REG_NEWLINE
+         $ matches \n at end        no     REG_NEWLINE
+         $ matches \n in middle     no     REG_NEWLINE
+         ^ matches \n in middle     no     REG_NEWLINE
+
+       PCRE's behaviour is the same as Perl's, except that there is no equiva-
+       lent for PCRE_DOLLAR_ENDONLY in Perl. In both PCRE and Perl,  there  is
+       no way to stop newline from matching [^a].
+
+       The   default  POSIX  newline  handling  can  be  obtained  by  setting
+       PCRE_DOTALL and PCRE_DOLLAR_ENDONLY, but there is no way to  make  PCRE
+       behave exactly as for the REG_NEWLINE action.
+
+
+MATCHING A PATTERN
+
+       The  function  regexec()  is  called  to  match a compiled pattern preg
+       against a given string, which is by default terminated by a  zero  byte
+       (but  see  REG_STARTEND below), subject to the options in eflags. These
+       can be:
+
+         REG_NOTBOL
+
+       The PCRE_NOTBOL option is set when calling the underlying PCRE matching
+       function.
+
+         REG_NOTEMPTY
+
+       The PCRE_NOTEMPTY option is set when calling the underlying PCRE match-
+       ing function. Note that REG_NOTEMPTY is not part of the POSIX standard.
+       However, setting this option can give more POSIX-like behaviour in some
+       situations.
+
+         REG_NOTEOL
+
+       The PCRE_NOTEOL option is set when calling the underlying PCRE matching
+       function.
+
+         REG_STARTEND
+
+       The  string  is  considered to start at string + pmatch[0].rm_so and to
+       have a terminating NUL located at string + pmatch[0].rm_eo (there  need
+       not  actually  be  a  NUL at that location), regardless of the value of
+       nmatch. This is a BSD extension, compatible with but not  specified  by
+       IEEE  Standard  1003.2  (POSIX.2),  and  should be used with caution in
+       software intended to be portable to other systems. Note that a non-zero
+       rm_so does not imply REG_NOTBOL; REG_STARTEND affects only the location
+       of the string, not how it is matched.
+
+       If the pattern was compiled with the REG_NOSUB flag, no data about  any
+       matched  strings  is  returned.  The  nmatch  and  pmatch  arguments of
+       regexec() are ignored.
+
+       If the value of nmatch is zero, or if the value pmatch is NULL, no data
+       about any matched strings is returned.
+
+       Otherwise,the portion of the string that was matched, and also any cap-
+       tured substrings, are returned via the pmatch argument, which points to
+       an  array  of nmatch structures of type regmatch_t, containing the mem-
+       bers rm_so and rm_eo. These contain the offset to the  first  character
+       of  each  substring and the offset to the first character after the end
+       of each substring, respectively. The 0th element of the vector  relates
+       to  the  entire portion of string that was matched; subsequent elements
+       relate to the capturing subpatterns of the regular  expression.  Unused
+       entries in the array have both structure members set to -1.
+
+       A  successful  match  yields  a  zero  return;  various error codes are
+       defined in the header file, of  which  REG_NOMATCH  is  the  "expected"
+       failure code.
+
+
+ERROR MESSAGES
+
+       The regerror() function maps a non-zero errorcode from either regcomp()
+       or regexec() to a printable message. If preg is  not  NULL,  the  error
+       should have arisen from the use of that structure. A message terminated
+       by a binary zero is placed  in  errbuf.  The  length  of  the  message,
+       including  the  zero, is limited to errbuf_size. The yield of the func-
+       tion is the size of buffer needed to hold the whole message.
+
+
+MEMORY USAGE
+
+       Compiling a regular expression causes memory to be allocated and  asso-
+       ciated  with  the preg structure. The function regfree() frees all such
+       memory, after which preg may no longer be used as  a  compiled  expres-
+       sion.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 09 January 2012
+       Copyright (c) 1997-2012 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCRECPP(3)                 Library Functions Manual                 PCRECPP(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions.
+
+SYNOPSIS OF C++ WRAPPER
+
+       #include 
+
+
+DESCRIPTION
+
+       The  C++  wrapper  for PCRE was provided by Google Inc. Some additional
+       functionality was added by Giuseppe Maxia. This brief man page was con-
+       structed  from  the  notes  in the pcrecpp.h file, which should be con-
+       sulted for further details. Note that the C++ wrapper supports only the
+       original  8-bit  PCRE  library. There is no 16-bit or 32-bit support at
+       present.
+
+
+MATCHING INTERFACE
+
+       The "FullMatch" operation checks that supplied text matches a  supplied
+       pattern  exactly.  If pointer arguments are supplied, it copies matched
+       sub-strings that match sub-patterns into them.
+
+         Example: successful match
+            pcrecpp::RE re("h.*o");
+            re.FullMatch("hello");
+
+         Example: unsuccessful match (requires full match):
+            pcrecpp::RE re("e");
+            !re.FullMatch("hello");
+
+         Example: creating a temporary RE object:
+            pcrecpp::RE("h.*o").FullMatch("hello");
+
+       You can pass in a "const char*" or a "string" for "text". The  examples
+       below  tend to use a const char*. You can, as in the different examples
+       above, store the RE object explicitly in a variable or use a  temporary
+       RE  object.  The  examples below use one mode or the other arbitrarily.
+       Either could correctly be used for any of these examples.
+
+       You must supply extra pointer arguments to extract matched subpieces.
+
+         Example: extracts "ruby" into "s" and 1234 into "i"
+            int i;
+            string s;
+            pcrecpp::RE re("(\\w+):(\\d+)");
+            re.FullMatch("ruby:1234", &s, &i);
+
+         Example: does not try to extract any extra sub-patterns
+            re.FullMatch("ruby:1234", &s);
+
+         Example: does not try to extract into NULL
+            re.FullMatch("ruby:1234", NULL, &i);
+
+         Example: integer overflow causes failure
+            !re.FullMatch("ruby:1234567891234", NULL, &i);
+
+         Example: fails because there aren't enough sub-patterns:
+            !pcrecpp::RE("\\w+:\\d+").FullMatch("ruby:1234", &s);
+
+         Example: fails because string cannot be stored in integer
+            !pcrecpp::RE("(.*)").FullMatch("ruby", &i);
+
+       The provided pointer arguments can be pointers to  any  scalar  numeric
+       type, or one of:
+
+          string        (matched piece is copied to string)
+          StringPiece   (StringPiece is mutated to point to matched piece)
+          T             (where "bool T::ParseFrom(const char*, int)" exists)
+          NULL          (the corresponding matched sub-pattern is not copied)
+
+       The  function returns true iff all of the following conditions are sat-
+       isfied:
+
+         a. "text" matches "pattern" exactly;
+
+         b. The number of matched sub-patterns is >= number of supplied
+            pointers;
+
+         c. The "i"th argument has a suitable type for holding the
+            string captured as the "i"th sub-pattern. If you pass in
+            void * NULL for the "i"th argument, or a non-void * NULL
+            of the correct type, or pass fewer arguments than the
+            number of sub-patterns, "i"th captured sub-pattern is
+            ignored.
+
+       CAVEAT: An optional sub-pattern that does  not  exist  in  the  matched
+       string  is  assigned  the  empty  string. Therefore, the following will
+       return false (because the empty string is not a valid number):
+
+          int number;
+          pcrecpp::RE::FullMatch("abc", "[a-z]+(\\d+)?", &number);
+
+       The matching interface supports at most 16 arguments per call.  If  you
+       need    more,    consider    using    the    more   general   interface
+       pcrecpp::RE::DoMatch. See pcrecpp.h for the signature for DoMatch.
+
+       NOTE: Do not use no_arg, which is used internally to mark the end of  a
+       list  of optional arguments, as a placeholder for missing arguments, as
+       this can lead to segfaults.
+
+
+QUOTING METACHARACTERS
+
+       You can use the "QuoteMeta" operation to insert backslashes before  all
+       potentially  meaningful  characters  in  a string. The returned string,
+       used as a regular expression, will exactly match the original string.
+
+         Example:
+            string quoted = RE::QuoteMeta(unquoted);
+
+       Note that it's legal to escape a character even if it  has  no  special
+       meaning  in  a  regular expression -- so this function does that. (This
+       also makes it identical to the perl function  of  the  same  name;  see
+       "perldoc    -f    quotemeta".)    For   example,   "1.5-2.0?"   becomes
+       "1\.5\-2\.0\?".
+
+
+PARTIAL MATCHES
+
+       You can use the "PartialMatch" operation when you want the  pattern  to
+       match any substring of the text.
+
+         Example: simple search for a string:
+            pcrecpp::RE("ell").PartialMatch("hello");
+
+         Example: find first number in a string:
+            int number;
+            pcrecpp::RE re("(\\d+)");
+            re.PartialMatch("x*100 + 20", &number);
+            assert(number == 100);
+
+
+UTF-8 AND THE MATCHING INTERFACE
+
+       By  default,  pattern  and text are plain text, one byte per character.
+       The UTF8 flag, passed to  the  constructor,  causes  both  pattern  and
+       string to be treated as UTF-8 text, still a byte stream but potentially
+       multiple bytes per character. In practice, the text is likelier  to  be
+       UTF-8  than  the pattern, but the match returned may depend on the UTF8
+       flag, so always use it when matching UTF8 text. For example,  "."  will
+       match  one  byte normally but with UTF8 set may match up to three bytes
+       of a multi-byte character.
+
+         Example:
+            pcrecpp::RE_Options options;
+            options.set_utf8();
+            pcrecpp::RE re(utf8_pattern, options);
+            re.FullMatch(utf8_string);
+
+         Example: using the convenience function UTF8():
+            pcrecpp::RE re(utf8_pattern, pcrecpp::UTF8());
+            re.FullMatch(utf8_string);
+
+       NOTE: The UTF8 flag is ignored if pcre was not configured with the
+             --enable-utf8 flag.
+
+
+PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE
+
+       PCRE defines some modifiers to  change  the  behavior  of  the  regular
+       expression   engine.  The  C++  wrapper  defines  an  auxiliary  class,
+       RE_Options, as a vehicle to pass such modifiers to  a  RE  class.  Cur-
+       rently, the following modifiers are supported:
+
+          modifier              description               Perl corresponding
+
+          PCRE_CASELESS         case insensitive match      /i
+          PCRE_MULTILINE        multiple lines match        /m
+          PCRE_DOTALL           dot matches newlines        /s
+          PCRE_DOLLAR_ENDONLY   $ matches only at end       N/A
+          PCRE_EXTRA            strict escape parsing       N/A
+          PCRE_EXTENDED         ignore white spaces         /x
+          PCRE_UTF8             handles UTF8 chars          built-in
+          PCRE_UNGREEDY         reverses * and *?           N/A
+          PCRE_NO_AUTO_CAPTURE  disables capturing parens   N/A (*)
+
+       (*)  Both Perl and PCRE allow non capturing parentheses by means of the
+       "?:" modifier within the pattern itself. e.g. (?:ab|cd) does  not  cap-
+       ture, while (ab|cd) does.
+
+       For  a  full  account on how each modifier works, please check the PCRE
+       API reference page.
+
+       For each modifier, there are two member functions whose  name  is  made
+       out  of  the  modifier  in  lowercase,  without the "PCRE_" prefix. For
+       instance, PCRE_CASELESS is handled by
+
+         bool caseless()
+
+       which returns true if the modifier is set, and
+
+         RE_Options & set_caseless(bool)
+
+       which sets or unsets the modifier. Moreover, PCRE_EXTRA_MATCH_LIMIT can
+       be  accessed  through  the  set_match_limit()  and match_limit() member
+       functions. Setting match_limit to a non-zero value will limit the  exe-
+       cution  of pcre to keep it from doing bad things like blowing the stack
+       or taking an eternity to return a result.  A  value  of  5000  is  good
+       enough  to stop stack blowup in a 2MB thread stack. Setting match_limit
+       to  zero  disables  match  limiting.  Alternatively,   you   can   call
+       match_limit_recursion()  which uses PCRE_EXTRA_MATCH_LIMIT_RECURSION to
+       limit how much  PCRE  recurses.  match_limit()  limits  the  number  of
+       matches PCRE does; match_limit_recursion() limits the depth of internal
+       recursion, and therefore the amount of stack that is used.
+
+       Normally, to pass one or more modifiers to a RE class,  you  declare  a
+       RE_Options object, set the appropriate options, and pass this object to
+       a RE constructor. Example:
+
+          RE_Options opt;
+          opt.set_caseless(true);
+          if (RE("HELLO", opt).PartialMatch("hello world")) ...
+
+       RE_options has two constructors. The default constructor takes no argu-
+       ments  and creates a set of flags that are off by default. The optional
+       parameter option_flags is to facilitate transfer of legacy code from  C
+       programs.  This lets you do
+
+          RE(pattern,
+            RE_Options(PCRE_CASELESS|PCRE_MULTILINE)).PartialMatch(str);
+
+       However, new code is better off doing
+
+          RE(pattern,
+            RE_Options().set_caseless(true).set_multiline(true))
+              .PartialMatch(str);
+
+       If you are going to pass one of the most used modifiers, there are some
+       convenience functions that return a RE_Options class with the appropri-
+       ate  modifier  already  set: CASELESS(), UTF8(), MULTILINE(), DOTALL(),
+       and EXTENDED().
+
+       If you need to set several options at once, and you don't  want  to  go
+       through  the pains of declaring a RE_Options object and setting several
+       options, there is a parallel method that give you such ability  on  the
+       fly.  You  can  concatenate several set_xxxxx() member functions, since
+       each of them returns a reference to its class object. For  example,  to
+       pass  PCRE_CASELESS, PCRE_EXTENDED, and PCRE_MULTILINE to a RE with one
+       statement, you may write:
+
+          RE(" ^ xyz \\s+ .* blah$",
+            RE_Options()
+              .set_caseless(true)
+              .set_extended(true)
+              .set_multiline(true)).PartialMatch(sometext);
+
+
+SCANNING TEXT INCREMENTALLY
+
+       The "Consume" operation may be useful if you want to  repeatedly  match
+       regular expressions at the front of a string and skip over them as they
+       match. This requires use of the "StringPiece" type, which represents  a
+       sub-range  of  a  real  string.  Like RE, StringPiece is defined in the
+       pcrecpp namespace.
+
+         Example: read lines of the form "var = value" from a string.
+            string contents = ...;                 // Fill string somehow
+            pcrecpp::StringPiece input(contents);  // Wrap in a StringPiece
+
+            string var;
+            int value;
+            pcrecpp::RE re("(\\w+) = (\\d+)\n");
+            while (re.Consume(&input, &var, &value)) {
+              ...;
+            }
+
+       Each successful call  to  "Consume"  will  set  "var/value",  and  also
+       advance "input" so it points past the matched text.
+
+       The  "FindAndConsume"  operation  is  similar to "Consume" but does not
+       anchor your match at the beginning of  the  string.  For  example,  you
+       could extract all words from a string by repeatedly calling
+
+         pcrecpp::RE("(\\w+)").FindAndConsume(&input, &word)
+
+
+PARSING HEX/OCTAL/C-RADIX NUMBERS
+
+       By default, if you pass a pointer to a numeric value, the corresponding
+       text is interpreted as a base-10  number.  You  can  instead  wrap  the
+       pointer with a call to one of the operators Hex(), Octal(), or CRadix()
+       to interpret the text in another base. The CRadix  operator  interprets
+       C-style  "0"  (base-8)  and  "0x"  (base-16)  prefixes, but defaults to
+       base-10.
+
+         Example:
+           int a, b, c, d;
+           pcrecpp::RE re("(.*) (.*) (.*) (.*)");
+           re.FullMatch("100 40 0100 0x40",
+                        pcrecpp::Octal(&a), pcrecpp::Hex(&b),
+                        pcrecpp::CRadix(&c), pcrecpp::CRadix(&d));
+
+       will leave 64 in a, b, c, and d.
+
+
+REPLACING PARTS OF STRINGS
+
+       You can replace the first match of "pattern" in "str"  with  "rewrite".
+       Within  "rewrite",  backslash-escaped  digits (\1 to \9) can be used to
+       insert text matching corresponding parenthesized group  from  the  pat-
+       tern. \0 in "rewrite" refers to the entire matching text. For example:
+
+         string s = "yabba dabba doo";
+         pcrecpp::RE("b+").Replace("d", &s);
+
+       will  leave  "s" containing "yada dabba doo". The result is true if the
+       pattern matches and a replacement occurs, false otherwise.
+
+       GlobalReplace is like Replace except that it replaces  all  occurrences
+       of  the  pattern  in  the string with the rewrite. Replacements are not
+       subject to re-matching. For example:
+
+         string s = "yabba dabba doo";
+         pcrecpp::RE("b+").GlobalReplace("d", &s);
+
+       will leave "s" containing "yada dada doo". It  returns  the  number  of
+       replacements made.
+
+       Extract  is like Replace, except that if the pattern matches, "rewrite"
+       is copied into "out" (an additional argument) with substitutions.   The
+       non-matching  portions  of "text" are ignored. Returns true iff a match
+       occurred and the extraction happened successfully;  if no match occurs,
+       the string is left unaffected.
+
+
+AUTHOR
+
+       The C++ wrapper was contributed by Google Inc.
+       Copyright (c) 2007 Google Inc.
+
+
+REVISION
+
+       Last updated: 08 January 2012
+------------------------------------------------------------------------------
+
+
+PCRESAMPLE(3)              Library Functions Manual              PCRESAMPLE(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+PCRE SAMPLE PROGRAM
+
+       A simple, complete demonstration program, to get you started with using
+       PCRE, is supplied in the file pcredemo.c in the  PCRE  distribution.  A
+       listing  of this program is given in the pcredemo documentation. If you
+       do not have a copy of the PCRE distribution, you can save this  listing
+       to re-create pcredemo.c.
+
+       The  demonstration program, which uses the original PCRE 8-bit library,
+       compiles the regular expression that is its first argument, and matches
+       it  against  the subject string in its second argument. No PCRE options
+       are set, and default character tables are used. If  matching  succeeds,
+       the  program  outputs the portion of the subject that matched, together
+       with the contents of any captured substrings.
+
+       If the -g option is given on the command line, the program then goes on
+       to check for further matches of the same regular expression in the same
+       subject string. The logic is a little bit tricky because of the  possi-
+       bility  of  matching an empty string. Comments in the code explain what
+       is going on.
+
+       If PCRE is installed in the standard include  and  library  directories
+       for your operating system, you should be able to compile the demonstra-
+       tion program using this command:
+
+         gcc -o pcredemo pcredemo.c -lpcre
+
+       If PCRE is installed elsewhere, you may need to add additional  options
+       to  the  command line. For example, on a Unix-like system that has PCRE
+       installed in /usr/local, you  can  compile  the  demonstration  program
+       using a command like this:
+
+         gcc -o pcredemo -I/usr/local/include pcredemo.c \
+             -L/usr/local/lib -lpcre
+
+       In  a  Windows  environment, if you want to statically link the program
+       against a non-dll pcre.a file, you must uncomment the line that defines
+       PCRE_STATIC  before  including  pcre.h, because otherwise the pcre_mal-
+       loc()   and   pcre_free()   exported   functions   will   be   declared
+       __declspec(dllimport), with unwanted results.
+
+       Once  you  have  compiled and linked the demonstration program, you can
+       run simple tests like this:
+
+         ./pcredemo 'cat|dog' 'the cat sat on the mat'
+         ./pcredemo -g 'cat|dog' 'the dog sat on the cat'
+
+       Note that there is a  much  more  comprehensive  test  program,  called
+       pcretest,  which  supports  many  more  facilities  for testing regular
+       expressions and both PCRE libraries. The pcredemo program  is  provided
+       as a simple coding example.
+
+       If  you  try to run pcredemo when PCRE is not installed in the standard
+       library directory, you may get an error like  this  on  some  operating
+       systems (e.g. Solaris):
+
+         ld.so.1:  a.out:  fatal:  libpcre.so.0:  open failed: No such file or
+       directory
+
+       This is caused by the way shared library support works  on  those  sys-
+       tems. You need to add
+
+         -R/usr/local/lib
+
+       (for example) to the compile command to get round this problem.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 10 January 2012
+       Copyright (c) 1997-2012 University of Cambridge.
+------------------------------------------------------------------------------
+PCRELIMITS(3)              Library Functions Manual              PCRELIMITS(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+SIZE AND OTHER LIMITATIONS
+
+       There  are some size limitations in PCRE but it is hoped that they will
+       never in practice be relevant.
+
+       The maximum length of a compiled  pattern  is  approximately  64K  data
+       units  (bytes  for  the  8-bit  library,  16-bit  units  for the 16-bit
+       library, and 32-bit units for the 32-bit library) if PCRE  is  compiled
+       with  the default internal linkage size, which is 2 bytes for the 8-bit
+       and 16-bit libraries, and 4 bytes for the 32-bit library. If  you  want
+       to process regular expressions that are truly enormous, you can compile
+       PCRE with an internal linkage size of 3 or 4 (when building the  16-bit
+       or  32-bit  library,  3 is rounded up to 4). See the README file in the
+       source distribution and the pcrebuild  documentation  for  details.  In
+       these  cases  the limit is substantially larger.  However, the speed of
+       execution is slower.
+
+       All values in repeating quantifiers must be less than 65536.
+
+       There is no limit to the number of parenthesized subpatterns, but there
+       can  be  no more than 65535 capturing subpatterns. There is, however, a
+       limit to the depth of  nesting  of  parenthesized  subpatterns  of  all
+       kinds.  This  is  imposed  in order to limit the amount of system stack
+       used at compile time. The limit can be specified when  PCRE  is  built;
+       the default is 250.
+
+       There is a limit to the number of forward references to subsequent sub-
+       patterns of around 200,000.  Repeated  forward  references  with  fixed
+       upper  limits,  for example, (?2){0,100} when subpattern number 2 is to
+       the right, are included in the count. There is no limit to  the  number
+       of backward references.
+
+       The maximum length of name for a named subpattern is 32 characters, and
+       the maximum number of named subpatterns is 10000.
+
+       The maximum length of a  name  in  a  (*MARK),  (*PRUNE),  (*SKIP),  or
+       (*THEN)  verb is 255 for the 8-bit library and 65535 for the 16-bit and
+       32-bit libraries.
+
+       The maximum length of a subject string is the largest  positive  number
+       that  an integer variable can hold. However, when using the traditional
+       matching function, PCRE uses recursion to handle subpatterns and indef-
+       inite  repetition.  This means that the available stack space may limit
+       the size of a subject string that can be processed by certain patterns.
+       For a discussion of stack issues, see the pcrestack documentation.
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 05 November 2013
+       Copyright (c) 1997-2013 University of Cambridge.
+------------------------------------------------------------------------------
+
+
+PCRESTACK(3)               Library Functions Manual               PCRESTACK(3)
+
+
+
+NAME
+       PCRE - Perl-compatible regular expressions
+
+PCRE DISCUSSION OF STACK USAGE
+
+       When  you call pcre[16|32]_exec(), it makes use of an internal function
+       called match(). This calls itself recursively at branch points  in  the
+       pattern,  in  order  to  remember the state of the match so that it can
+       back up and try a different alternative if  the  first  one  fails.  As
+       matching proceeds deeper and deeper into the tree of possibilities, the
+       recursion depth increases. The match() function is also called in other
+       circumstances,  for  example,  whenever  a parenthesized sub-pattern is
+       entered, and in certain cases of repetition.
+
+       Not all calls of match() increase the recursion depth; for an item such
+       as  a* it may be called several times at the same level, after matching
+       different numbers of a's. Furthermore, in a number of cases  where  the
+       result  of  the  recursive call would immediately be passed back as the
+       result of the current call (a "tail recursion"), the function  is  just
+       restarted instead.
+
+       The  above  comments apply when pcre[16|32]_exec() is run in its normal
+       interpretive  manner.   If   the   pattern   was   studied   with   the
+       PCRE_STUDY_JIT_COMPILE  option, and just-in-time compiling was success-
+       ful, and the options passed to pcre[16|32]_exec() were  not  incompati-
+       ble,  the  matching  process  uses the JIT-compiled code instead of the
+       match() function. In this case, the  memory  requirements  are  handled
+       entirely differently. See the pcrejit documentation for details.
+
+       The  pcre[16|32]_dfa_exec()  function operates in an entirely different
+       way, and uses recursion only when there is a regular expression  recur-
+       sion or subroutine call in the pattern. This includes the processing of
+       assertion and "once-only" subpatterns, which are handled  like  subrou-
+       tine  calls.  Normally, these are never very deep, and the limit on the
+       complexity of pcre[16|32]_dfa_exec() is controlled  by  the  amount  of
+       workspace  it is given.  However, it is possible to write patterns with
+       runaway    infinite    recursions;    such    patterns    will    cause
+       pcre[16|32]_dfa_exec()  to  run  out  of stack. At present, there is no
+       protection against this.
+
+       The comments that follow do NOT apply to  pcre[16|32]_dfa_exec();  they
+       are relevant only for pcre[16|32]_exec() without the JIT optimization.
+
+   Reducing pcre[16|32]_exec()'s stack usage
+
+       Each  time  that match() is actually called recursively, it uses memory
+       from the process stack. For certain kinds of  pattern  and  data,  very
+       large  amounts of stack may be needed, despite the recognition of "tail
+       recursion".  You can often reduce the amount of recursion,  and  there-
+       fore  the  amount of stack used, by modifying the pattern that is being
+       matched. Consider, for example, this pattern:
+
+         ([^<]|<(?!inet))+
+
+       It matches from wherever it starts until it encounters "
+.
+.
+.SH "PCRE 16-BIT API BASIC FUNCTIONS"
+.rs
+.sp
+.nf
+.B pcre16 *pcre16_compile(PCRE_SPTR16 \fIpattern\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre16 *pcre16_compile2(PCRE_SPTR16 \fIpattern\fP, int \fIoptions\fP,
+.B "     int *\fIerrorcodeptr\fP,"
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre16_extra *pcre16_study(const pcre16 *\fIcode\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP);"
+.sp
+.B void pcre16_free_study(pcre16_extra *\fIextra\fP);
+.sp
+.B int pcre16_exec(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
+.B "     PCRE_SPTR16 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);"
+.sp
+.B int pcre16_dfa_exec(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
+.B "     PCRE_SPTR16 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     int *\fIworkspace\fP, int \fIwscount\fP);"
+.fi
+.
+.
+.SH "PCRE 16-BIT API STRING EXTRACTION FUNCTIONS"
+.rs
+.sp
+.nf
+.B int pcre16_copy_named_substring(const pcre16 *\fIcode\fP,
+.B "     PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, PCRE_SPTR16 \fIstringname\fP,"
+.B "     PCRE_UCHAR16 *\fIbuffer\fP, int \fIbuffersize\fP);"
+.sp
+.B int pcre16_copy_substring(PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP, PCRE_UCHAR16 *\fIbuffer\fP,"
+.B "     int \fIbuffersize\fP);"
+.sp
+.B int pcre16_get_named_substring(const pcre16 *\fIcode\fP,
+.B "     PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, PCRE_SPTR16 \fIstringname\fP,"
+.B "     PCRE_SPTR16 *\fIstringptr\fP);"
+.sp
+.B int pcre16_get_stringnumber(const pcre16 *\fIcode\fP,
+.B "     PCRE_SPTR16 \fIname\fP);
+.sp
+.B int pcre16_get_stringtable_entries(const pcre16 *\fIcode\fP,
+.B "     PCRE_SPTR16 \fIname\fP, PCRE_UCHAR16 **\fIfirst\fP, PCRE_UCHAR16 **\fIlast\fP);"
+.sp
+.B int pcre16_get_substring(PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP,"
+.B "     PCRE_SPTR16 *\fIstringptr\fP);"
+.sp
+.B int pcre16_get_substring_list(PCRE_SPTR16 \fIsubject\fP,
+.B "     int *\fIovector\fP, int \fIstringcount\fP, PCRE_SPTR16 **\fIlistptr\fP);"
+.sp
+.B void pcre16_free_substring(PCRE_SPTR16 \fIstringptr\fP);
+.sp
+.B void pcre16_free_substring_list(PCRE_SPTR16 *\fIstringptr\fP);
+.fi
+.
+.
+.SH "PCRE 16-BIT API AUXILIARY FUNCTIONS"
+.rs
+.sp
+.nf
+.B pcre16_jit_stack *pcre16_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
+.sp
+.B void pcre16_jit_stack_free(pcre16_jit_stack *\fIstack\fP);
+.sp
+.B void pcre16_assign_jit_stack(pcre16_extra *\fIextra\fP,
+.B "     pcre16_jit_callback \fIcallback\fP, void *\fIdata\fP);"
+.sp
+.B const unsigned char *pcre16_maketables(void);
+.sp
+.B int pcre16_fullinfo(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
+.B "     int \fIwhat\fP, void *\fIwhere\fP);"
+.sp
+.B int pcre16_refcount(pcre16 *\fIcode\fP, int \fIadjust\fP);
+.sp
+.B int pcre16_config(int \fIwhat\fP, void *\fIwhere\fP);
+.sp
+.B const char *pcre16_version(void);
+.sp
+.B int pcre16_pattern_to_host_byte_order(pcre16 *\fIcode\fP,
+.B "     pcre16_extra *\fIextra\fP, const unsigned char *\fItables\fP);"
+.fi
+.
+.
+.SH "PCRE 16-BIT API INDIRECTED FUNCTIONS"
+.rs
+.sp
+.nf
+.B void *(*pcre16_malloc)(size_t);
+.sp
+.B void (*pcre16_free)(void *);
+.sp
+.B void *(*pcre16_stack_malloc)(size_t);
+.sp
+.B void (*pcre16_stack_free)(void *);
+.sp
+.B int (*pcre16_callout)(pcre16_callout_block *);
+.fi
+.
+.
+.SH "PCRE 16-BIT API 16-BIT-ONLY FUNCTION"
+.rs
+.sp
+.nf
+.B int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *\fIoutput\fP,
+.B "     PCRE_SPTR16 \fIinput\fP, int \fIlength\fP, int *\fIbyte_order\fP,"
+.B "     int \fIkeep_boms\fP);"
+.fi
+.
+.
+.SH "THE PCRE 16-BIT LIBRARY"
+.rs
+.sp
+Starting with release 8.30, it is possible to compile a PCRE library that
+supports 16-bit character strings, including UTF-16 strings, as well as or
+instead of the original 8-bit library. The majority of the work to make this
+possible was done by Zoltan Herczeg. The two libraries contain identical sets
+of functions, used in exactly the same way. Only the names of the functions and
+the data types of their arguments and results are different. To avoid
+over-complication and reduce the documentation maintenance load, most of the
+PCRE documentation describes the 8-bit library, with only occasional references
+to the 16-bit library. This page describes what is different when you use the
+16-bit library.
+.P
+WARNING: A single application can be linked with both libraries, but you must
+take care when processing any particular pattern to use functions from just one
+library. For example, if you want to study a pattern that was compiled with
+\fBpcre16_compile()\fP, you must do so with \fBpcre16_study()\fP, not
+\fBpcre_study()\fP, and you must free the study data with
+\fBpcre16_free_study()\fP.
+.
+.
+.SH "THE HEADER FILE"
+.rs
+.sp
+There is only one header file, \fBpcre.h\fP. It contains prototypes for all the
+functions in all libraries, as well as definitions of flags, structures, error
+codes, etc.
+.
+.
+.SH "THE LIBRARY NAME"
+.rs
+.sp
+In Unix-like systems, the 16-bit library is called \fBlibpcre16\fP, and can
+normally be accesss by adding \fB-lpcre16\fP to the command for linking an
+application that uses PCRE.
+.
+.
+.SH "STRING TYPES"
+.rs
+.sp
+In the 8-bit library, strings are passed to PCRE library functions as vectors
+of bytes with the C type "char *". In the 16-bit library, strings are passed as
+vectors of unsigned 16-bit quantities. The macro PCRE_UCHAR16 specifies an
+appropriate data type, and PCRE_SPTR16 is defined as "const PCRE_UCHAR16 *". In
+very many environments, "short int" is a 16-bit data type. When PCRE is built,
+it defines PCRE_UCHAR16 as "unsigned short int", but checks that it really is a
+16-bit data type. If it is not, the build fails with an error message telling
+the maintainer to modify the definition appropriately.
+.
+.
+.SH "STRUCTURE TYPES"
+.rs
+.sp
+The types of the opaque structures that are used for compiled 16-bit patterns
+and JIT stacks are \fBpcre16\fP and \fBpcre16_jit_stack\fP respectively. The
+type of the user-accessible structure that is returned by \fBpcre16_study()\fP
+is \fBpcre16_extra\fP, and the type of the structure that is used for passing
+data to a callout function is \fBpcre16_callout_block\fP. These structures
+contain the same fields, with the same names, as their 8-bit counterparts. The
+only difference is that pointers to character strings are 16-bit instead of
+8-bit types.
+.
+.
+.SH "16-BIT FUNCTIONS"
+.rs
+.sp
+For every function in the 8-bit library there is a corresponding function in
+the 16-bit library with a name that starts with \fBpcre16_\fP instead of
+\fBpcre_\fP. The prototypes are listed above. In addition, there is one extra
+function, \fBpcre16_utf16_to_host_byte_order()\fP. This is a utility function
+that converts a UTF-16 character string to host byte order if necessary. The
+other 16-bit functions expect the strings they are passed to be in host byte
+order.
+.P
+The \fIinput\fP and \fIoutput\fP arguments of
+\fBpcre16_utf16_to_host_byte_order()\fP may point to the same address, that is,
+conversion in place is supported. The output buffer must be at least as long as
+the input.
+.P
+The \fIlength\fP argument specifies the number of 16-bit data units in the
+input string; a negative value specifies a zero-terminated string.
+.P
+If \fIbyte_order\fP is NULL, it is assumed that the string starts off in host
+byte order. This may be changed by byte-order marks (BOMs) anywhere in the
+string (commonly as the first character).
+.P
+If \fIbyte_order\fP is not NULL, a non-zero value of the integer to which it
+points means that the input starts off in host byte order, otherwise the
+opposite order is assumed. Again, BOMs in the string can change this. The final
+byte order is passed back at the end of processing.
+.P
+If \fIkeep_boms\fP is not zero, byte-order mark characters (0xfeff) are copied
+into the output string. Otherwise they are discarded.
+.P
+The result of the function is the number of 16-bit units placed into the output
+buffer, including the zero terminator if the string was zero-terminated.
+.
+.
+.SH "SUBJECT STRING OFFSETS"
+.rs
+.sp
+The lengths and starting offsets of subject strings must be specified in 16-bit
+data units, and the offsets within subject strings that are returned by the
+matching functions are in also 16-bit units rather than bytes.
+.
+.
+.SH "NAMED SUBPATTERNS"
+.rs
+.sp
+The name-to-number translation table that is maintained for named subpatterns
+uses 16-bit characters. The \fBpcre16_get_stringtable_entries()\fP function
+returns the length of each entry in the table as the number of 16-bit data
+units.
+.
+.
+.SH "OPTION NAMES"
+.rs
+.sp
+There are two new general option names, PCRE_UTF16 and PCRE_NO_UTF16_CHECK,
+which correspond to PCRE_UTF8 and PCRE_NO_UTF8_CHECK in the 8-bit library. In
+fact, these new options define the same bits in the options word. There is a
+discussion about the
+.\" HTML 
+.\" 
+validity of UTF-16 strings
+.\"
+in the
+.\" HREF
+\fBpcreunicode\fP
+.\"
+page.
+.P
+For the \fBpcre16_config()\fP function there is an option PCRE_CONFIG_UTF16
+that returns 1 if UTF-16 support is configured, otherwise 0. If this option is
+given to \fBpcre_config()\fP or \fBpcre32_config()\fP, or if the
+PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF32 option is given to \fBpcre16_config()\fP,
+the result is the PCRE_ERROR_BADOPTION error.
+.
+.
+.SH "CHARACTER CODES"
+.rs
+.sp
+In 16-bit mode, when PCRE_UTF16 is not set, character values are treated in the
+same way as in 8-bit, non UTF-8 mode, except, of course, that they can range
+from 0 to 0xffff instead of 0 to 0xff. Character types for characters less than
+0xff can therefore be influenced by the locale in the same way as before.
+Characters greater than 0xff have only one case, and no "type" (such as letter
+or digit).
+.P
+In UTF-16 mode, the character code is Unicode, in the range 0 to 0x10ffff, with
+the exception of values in the range 0xd800 to 0xdfff because those are
+"surrogate" values that are used in pairs to encode values greater than 0xffff.
+.P
+A UTF-16 string can indicate its endianness by special code knows as a
+byte-order mark (BOM). The PCRE functions do not handle this, expecting strings
+to be in host byte order. A utility function called
+\fBpcre16_utf16_to_host_byte_order()\fP is provided to help with this (see
+above).
+.
+.
+.SH "ERROR NAMES"
+.rs
+.sp
+The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16 correspond to
+their 8-bit counterparts. The error PCRE_ERROR_BADMODE is given when a compiled
+pattern is passed to a function that processes patterns in the other
+mode, for example, if a pattern compiled with \fBpcre_compile()\fP is passed to
+\fBpcre16_exec()\fP.
+.P
+There are new error codes whose names begin with PCRE_UTF16_ERR for invalid
+UTF-16 strings, corresponding to the PCRE_UTF8_ERR codes for UTF-8 strings that
+are described in the section entitled
+.\" HTML 
+.\" 
+"Reason codes for invalid UTF-8 strings"
+.\"
+in the main
+.\" HREF
+\fBpcreapi\fP
+.\"
+page. The UTF-16 errors are:
+.sp
+  PCRE_UTF16_ERR1  Missing low surrogate at end of string
+  PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
+  PCRE_UTF16_ERR3  Isolated low surrogate
+  PCRE_UTF16_ERR4  Non-character
+.
+.
+.SH "ERROR TEXTS"
+.rs
+.sp
+If there is an error while compiling a pattern, the error text that is passed
+back by \fBpcre16_compile()\fP or \fBpcre16_compile2()\fP is still an 8-bit
+character string, zero-terminated.
+.
+.
+.SH "CALLOUTS"
+.rs
+.sp
+The \fIsubject\fP and \fImark\fP fields in the callout block that is passed to
+a callout function point to 16-bit vectors.
+.
+.
+.SH "TESTING"
+.rs
+.sp
+The \fBpcretest\fP program continues to operate with 8-bit input and output
+files, but it can be used for testing the 16-bit library. If it is run with the
+command line option \fB-16\fP, patterns and subject strings are converted from
+8-bit to 16-bit before being passed to PCRE, and the 16-bit library functions
+are used instead of the 8-bit ones. Returned 16-bit strings are converted to
+8-bit for output. If both the 8-bit and the 32-bit libraries were not compiled,
+\fBpcretest\fP defaults to 16-bit and the \fB-16\fP option is ignored.
+.P
+When PCRE is being built, the \fBRunTest\fP script that is called by "make
+check" uses the \fBpcretest\fP \fB-C\fP option to discover which of the 8-bit,
+16-bit and 32-bit libraries has been built, and runs the tests appropriately.
+.
+.
+.SH "NOT SUPPORTED IN 16-BIT MODE"
+.rs
+.sp
+Not all the features of the 8-bit library are available with the 16-bit
+library. The C++ and POSIX wrapper functions support only the 8-bit library,
+and the \fBpcregrep\fP program is at present 8-bit only.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 12 May 2013
+Copyright (c) 1997-2013 University of Cambridge.
+.fi
diff --git a/doc/pcre32.3 b/doc/pcre32.3
new file mode 100644
index 0000000..7cde8c0
--- /dev/null
+++ b/doc/pcre32.3
@@ -0,0 +1,369 @@
+.TH PCRE 3 "12 May 2013" "PCRE 8.33"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.sp
+.B #include 
+.
+.
+.SH "PCRE 32-BIT API BASIC FUNCTIONS"
+.rs
+.sp
+.nf
+.B pcre32 *pcre32_compile(PCRE_SPTR32 \fIpattern\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre32 *pcre32_compile2(PCRE_SPTR32 \fIpattern\fP, int \fIoptions\fP,
+.B "     int *\fIerrorcodeptr\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre32_extra *pcre32_study(const pcre32 *\fIcode\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP);"
+.sp
+.B void pcre32_free_study(pcre32_extra *\fIextra\fP);
+.sp
+.B int pcre32_exec(const pcre32 *\fIcode\fP, "const pcre32_extra *\fIextra\fP,"
+.B "     PCRE_SPTR32 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);"
+.sp
+.B int pcre32_dfa_exec(const pcre32 *\fIcode\fP, "const pcre32_extra *\fIextra\fP,"
+.B "     PCRE_SPTR32 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     int *\fIworkspace\fP, int \fIwscount\fP);"
+.fi
+.
+.
+.SH "PCRE 32-BIT API STRING EXTRACTION FUNCTIONS"
+.rs
+.sp
+.nf
+.B int pcre32_copy_named_substring(const pcre32 *\fIcode\fP,
+.B "     PCRE_SPTR32 \fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, PCRE_SPTR32 \fIstringname\fP,"
+.B "     PCRE_UCHAR32 *\fIbuffer\fP, int \fIbuffersize\fP);"
+.sp
+.B int pcre32_copy_substring(PCRE_SPTR32 \fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP, PCRE_UCHAR32 *\fIbuffer\fP,"
+.B "     int \fIbuffersize\fP);"
+.sp
+.B int pcre32_get_named_substring(const pcre32 *\fIcode\fP,
+.B "     PCRE_SPTR32 \fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, PCRE_SPTR32 \fIstringname\fP,"
+.B "     PCRE_SPTR32 *\fIstringptr\fP);"
+.sp
+.B int pcre32_get_stringnumber(const pcre32 *\fIcode\fP,
+.B "     PCRE_SPTR32 \fIname\fP);"
+.sp
+.B int pcre32_get_stringtable_entries(const pcre32 *\fIcode\fP,
+.B "     PCRE_SPTR32 \fIname\fP, PCRE_UCHAR32 **\fIfirst\fP, PCRE_UCHAR32 **\fIlast\fP);"
+.sp
+.B int pcre32_get_substring(PCRE_SPTR32 \fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP,"
+.B "     PCRE_SPTR32 *\fIstringptr\fP);"
+.sp
+.B int pcre32_get_substring_list(PCRE_SPTR32 \fIsubject\fP,
+.B "     int *\fIovector\fP, int \fIstringcount\fP, PCRE_SPTR32 **\fIlistptr\fP);"
+.sp
+.B void pcre32_free_substring(PCRE_SPTR32 \fIstringptr\fP);
+.sp
+.B void pcre32_free_substring_list(PCRE_SPTR32 *\fIstringptr\fP);
+.fi
+.
+.
+.SH "PCRE 32-BIT API AUXILIARY FUNCTIONS"
+.rs
+.sp
+.nf
+.B pcre32_jit_stack *pcre32_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
+.sp
+.B void pcre32_jit_stack_free(pcre32_jit_stack *\fIstack\fP);
+.sp
+.B void pcre32_assign_jit_stack(pcre32_extra *\fIextra\fP,
+.B "     pcre32_jit_callback \fIcallback\fP, void *\fIdata\fP);"
+.sp
+.B const unsigned char *pcre32_maketables(void);
+.sp
+.B int pcre32_fullinfo(const pcre32 *\fIcode\fP, "const pcre32_extra *\fIextra\fP,"
+.B "     int \fIwhat\fP, void *\fIwhere\fP);"
+.sp
+.B int pcre32_refcount(pcre32 *\fIcode\fP, int \fIadjust\fP);
+.sp
+.B int pcre32_config(int \fIwhat\fP, void *\fIwhere\fP);
+.sp
+.B const char *pcre32_version(void);
+.sp
+.B int pcre32_pattern_to_host_byte_order(pcre32 *\fIcode\fP,
+.B "     pcre32_extra *\fIextra\fP, const unsigned char *\fItables\fP);"
+.fi
+.
+.
+.SH "PCRE 32-BIT API INDIRECTED FUNCTIONS"
+.rs
+.sp
+.nf
+.B void *(*pcre32_malloc)(size_t);
+.sp
+.B void (*pcre32_free)(void *);
+.sp
+.B void *(*pcre32_stack_malloc)(size_t);
+.sp
+.B void (*pcre32_stack_free)(void *);
+.sp
+.B int (*pcre32_callout)(pcre32_callout_block *);
+.fi
+.
+.
+.SH "PCRE 32-BIT API 32-BIT-ONLY FUNCTION"
+.rs
+.sp
+.nf
+.B int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *\fIoutput\fP,
+.B "     PCRE_SPTR32 \fIinput\fP, int \fIlength\fP, int *\fIbyte_order\fP,"
+.B "     int \fIkeep_boms\fP);"
+.fi
+.
+.
+.SH "THE PCRE 32-BIT LIBRARY"
+.rs
+.sp
+Starting with release 8.32, it is possible to compile a PCRE library that
+supports 32-bit character strings, including UTF-32 strings, as well as or
+instead of the original 8-bit library. This work was done by Christian Persch,
+based on the work done by Zoltan Herczeg for the 16-bit library. All three
+libraries contain identical sets of functions, used in exactly the same way.
+Only the names of the functions and the data types of their arguments and
+results are different. To avoid over-complication and reduce the documentation
+maintenance load, most of the PCRE documentation describes the 8-bit library,
+with only occasional references to the 16-bit and 32-bit libraries. This page
+describes what is different when you use the 32-bit library.
+.P
+WARNING: A single application can be linked with all or any of the three
+libraries, but you must take care when processing any particular pattern
+to use functions from just one library. For example, if you want to study
+a pattern that was compiled with \fBpcre32_compile()\fP, you must do so
+with \fBpcre32_study()\fP, not \fBpcre_study()\fP, and you must free the
+study data with \fBpcre32_free_study()\fP.
+.
+.
+.SH "THE HEADER FILE"
+.rs
+.sp
+There is only one header file, \fBpcre.h\fP. It contains prototypes for all the
+functions in all libraries, as well as definitions of flags, structures, error
+codes, etc.
+.
+.
+.SH "THE LIBRARY NAME"
+.rs
+.sp
+In Unix-like systems, the 32-bit library is called \fBlibpcre32\fP, and can
+normally be accesss by adding \fB-lpcre32\fP to the command for linking an
+application that uses PCRE.
+.
+.
+.SH "STRING TYPES"
+.rs
+.sp
+In the 8-bit library, strings are passed to PCRE library functions as vectors
+of bytes with the C type "char *". In the 32-bit library, strings are passed as
+vectors of unsigned 32-bit quantities. The macro PCRE_UCHAR32 specifies an
+appropriate data type, and PCRE_SPTR32 is defined as "const PCRE_UCHAR32 *". In
+very many environments, "unsigned int" is a 32-bit data type. When PCRE is
+built, it defines PCRE_UCHAR32 as "unsigned int", but checks that it really is
+a 32-bit data type. If it is not, the build fails with an error message telling
+the maintainer to modify the definition appropriately.
+.
+.
+.SH "STRUCTURE TYPES"
+.rs
+.sp
+The types of the opaque structures that are used for compiled 32-bit patterns
+and JIT stacks are \fBpcre32\fP and \fBpcre32_jit_stack\fP respectively. The
+type of the user-accessible structure that is returned by \fBpcre32_study()\fP
+is \fBpcre32_extra\fP, and the type of the structure that is used for passing
+data to a callout function is \fBpcre32_callout_block\fP. These structures
+contain the same fields, with the same names, as their 8-bit counterparts. The
+only difference is that pointers to character strings are 32-bit instead of
+8-bit types.
+.
+.
+.SH "32-BIT FUNCTIONS"
+.rs
+.sp
+For every function in the 8-bit library there is a corresponding function in
+the 32-bit library with a name that starts with \fBpcre32_\fP instead of
+\fBpcre_\fP. The prototypes are listed above. In addition, there is one extra
+function, \fBpcre32_utf32_to_host_byte_order()\fP. This is a utility function
+that converts a UTF-32 character string to host byte order if necessary. The
+other 32-bit functions expect the strings they are passed to be in host byte
+order.
+.P
+The \fIinput\fP and \fIoutput\fP arguments of
+\fBpcre32_utf32_to_host_byte_order()\fP may point to the same address, that is,
+conversion in place is supported. The output buffer must be at least as long as
+the input.
+.P
+The \fIlength\fP argument specifies the number of 32-bit data units in the
+input string; a negative value specifies a zero-terminated string.
+.P
+If \fIbyte_order\fP is NULL, it is assumed that the string starts off in host
+byte order. This may be changed by byte-order marks (BOMs) anywhere in the
+string (commonly as the first character).
+.P
+If \fIbyte_order\fP is not NULL, a non-zero value of the integer to which it
+points means that the input starts off in host byte order, otherwise the
+opposite order is assumed. Again, BOMs in the string can change this. The final
+byte order is passed back at the end of processing.
+.P
+If \fIkeep_boms\fP is not zero, byte-order mark characters (0xfeff) are copied
+into the output string. Otherwise they are discarded.
+.P
+The result of the function is the number of 32-bit units placed into the output
+buffer, including the zero terminator if the string was zero-terminated.
+.
+.
+.SH "SUBJECT STRING OFFSETS"
+.rs
+.sp
+The lengths and starting offsets of subject strings must be specified in 32-bit
+data units, and the offsets within subject strings that are returned by the
+matching functions are in also 32-bit units rather than bytes.
+.
+.
+.SH "NAMED SUBPATTERNS"
+.rs
+.sp
+The name-to-number translation table that is maintained for named subpatterns
+uses 32-bit characters. The \fBpcre32_get_stringtable_entries()\fP function
+returns the length of each entry in the table as the number of 32-bit data
+units.
+.
+.
+.SH "OPTION NAMES"
+.rs
+.sp
+There are two new general option names, PCRE_UTF32 and PCRE_NO_UTF32_CHECK,
+which correspond to PCRE_UTF8 and PCRE_NO_UTF8_CHECK in the 8-bit library. In
+fact, these new options define the same bits in the options word. There is a
+discussion about the
+.\" HTML 
+.\" 
+validity of UTF-32 strings
+.\"
+in the
+.\" HREF
+\fBpcreunicode\fP
+.\"
+page.
+.P
+For the \fBpcre32_config()\fP function there is an option PCRE_CONFIG_UTF32
+that returns 1 if UTF-32 support is configured, otherwise 0. If this option is
+given to \fBpcre_config()\fP or \fBpcre16_config()\fP, or if the
+PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF16 option is given to \fBpcre32_config()\fP,
+the result is the PCRE_ERROR_BADOPTION error.
+.
+.
+.SH "CHARACTER CODES"
+.rs
+.sp
+In 32-bit mode, when PCRE_UTF32 is not set, character values are treated in the
+same way as in 8-bit, non UTF-8 mode, except, of course, that they can range
+from 0 to 0x7fffffff instead of 0 to 0xff. Character types for characters less
+than 0xff can therefore be influenced by the locale in the same way as before.
+Characters greater than 0xff have only one case, and no "type" (such as letter
+or digit).
+.P
+In UTF-32 mode, the character code is Unicode, in the range 0 to 0x10ffff, with
+the exception of values in the range 0xd800 to 0xdfff because those are
+"surrogate" values that are ill-formed in UTF-32.
+.P
+A UTF-32 string can indicate its endianness by special code knows as a
+byte-order mark (BOM). The PCRE functions do not handle this, expecting strings
+to be in host byte order. A utility function called
+\fBpcre32_utf32_to_host_byte_order()\fP is provided to help with this (see
+above).
+.
+.
+.SH "ERROR NAMES"
+.rs
+.sp
+The error PCRE_ERROR_BADUTF32 corresponds to its 8-bit counterpart.
+The error PCRE_ERROR_BADMODE is given when a compiled
+pattern is passed to a function that processes patterns in the other
+mode, for example, if a pattern compiled with \fBpcre_compile()\fP is passed to
+\fBpcre32_exec()\fP.
+.P
+There are new error codes whose names begin with PCRE_UTF32_ERR for invalid
+UTF-32 strings, corresponding to the PCRE_UTF8_ERR codes for UTF-8 strings that
+are described in the section entitled
+.\" HTML 
+.\" 
+"Reason codes for invalid UTF-8 strings"
+.\"
+in the main
+.\" HREF
+\fBpcreapi\fP
+.\"
+page. The UTF-32 errors are:
+.sp
+  PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
+  PCRE_UTF32_ERR2  Non-character
+  PCRE_UTF32_ERR3  Character > 0x10ffff
+.
+.
+.SH "ERROR TEXTS"
+.rs
+.sp
+If there is an error while compiling a pattern, the error text that is passed
+back by \fBpcre32_compile()\fP or \fBpcre32_compile2()\fP is still an 8-bit
+character string, zero-terminated.
+.
+.
+.SH "CALLOUTS"
+.rs
+.sp
+The \fIsubject\fP and \fImark\fP fields in the callout block that is passed to
+a callout function point to 32-bit vectors.
+.
+.
+.SH "TESTING"
+.rs
+.sp
+The \fBpcretest\fP program continues to operate with 8-bit input and output
+files, but it can be used for testing the 32-bit library. If it is run with the
+command line option \fB-32\fP, patterns and subject strings are converted from
+8-bit to 32-bit before being passed to PCRE, and the 32-bit library functions
+are used instead of the 8-bit ones. Returned 32-bit strings are converted to
+8-bit for output. If both the 8-bit and the 16-bit libraries were not compiled,
+\fBpcretest\fP defaults to 32-bit and the \fB-32\fP option is ignored.
+.P
+When PCRE is being built, the \fBRunTest\fP script that is called by "make
+check" uses the \fBpcretest\fP \fB-C\fP option to discover which of the 8-bit,
+16-bit and 32-bit libraries has been built, and runs the tests appropriately.
+.
+.
+.SH "NOT SUPPORTED IN 32-BIT MODE"
+.rs
+.sp
+Not all the features of the 8-bit library are available with the 32-bit
+library. The C++ and POSIX wrapper functions support only the 8-bit library,
+and the \fBpcregrep\fP program is at present 8-bit only.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 12 May 2013
+Copyright (c) 1997-2013 University of Cambridge.
+.fi
diff --git a/doc/pcre_assign_jit_stack.3 b/doc/pcre_assign_jit_stack.3
new file mode 100644
index 0000000..0ecf6f2
--- /dev/null
+++ b/doc/pcre_assign_jit_stack.3
@@ -0,0 +1,59 @@
+.TH PCRE_ASSIGN_JIT_STACK 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
+.B "     pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);"
+.sp
+.B void pcre16_assign_jit_stack(pcre16_extra *\fIextra\fP,
+.B "     pcre16_jit_callback \fIcallback\fP, void *\fIdata\fP);"
+.sp
+.B void pcre32_assign_jit_stack(pcre32_extra *\fIextra\fP,
+.B "     pcre32_jit_callback \fIcallback\fP, void *\fIdata\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function provides control over the memory used as a stack at run-time by a
+call to \fBpcre[16|32]_exec()\fP with a pattern that has been successfully
+compiled with JIT optimization. The arguments are:
+.sp
+  extra     the data pointer returned by \fBpcre[16|32]_study()\fP
+  callback  a callback function
+  data      a JIT stack or a value to be passed to the callback
+              function
+.P
+If \fIcallback\fP is NULL and \fIdata\fP is NULL, an internal 32K block on
+the machine stack is used.
+.P
+If \fIcallback\fP is NULL and \fIdata\fP is not NULL, \fIdata\fP must
+be a valid JIT stack, the result of calling \fBpcre[16|32]_jit_stack_alloc()\fP.
+.P
+If \fIcallback\fP not NULL, it is called with \fIdata\fP as an argument at
+the start of matching, in order to set up a JIT stack. If the result is NULL,
+the internal 32K stack is used; otherwise the return value must be a valid JIT
+stack, the result of calling \fBpcre[16|32]_jit_stack_alloc()\fP.
+.P
+You may safely assign the same JIT stack to multiple patterns, as long as they
+are all matched in the same thread. In a multithread application, each thread
+must use its own JIT stack. For more details, see the
+.\" HREF
+\fBpcrejit\fP
+.\"
+page.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_compile.3 b/doc/pcre_compile.3
new file mode 100644
index 0000000..5c16ebe
--- /dev/null
+++ b/doc/pcre_compile.3
@@ -0,0 +1,96 @@
+.TH PCRE_COMPILE 3 "01 October 2013" "PCRE 8.34"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre16 *pcre16_compile(PCRE_SPTR16 \fIpattern\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre32 *pcre32_compile(PCRE_SPTR32 \fIpattern\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function compiles a regular expression into an internal form. It is the
+same as \fBpcre[16|32]_compile2()\fP, except for the absence of the
+\fIerrorcodeptr\fP argument. Its arguments are:
+.sp
+  \fIpattern\fP       A zero-terminated string containing the
+                  regular expression to be compiled
+  \fIoptions\fP       Zero or more option bits
+  \fIerrptr\fP        Where to put an error message
+  \fIerroffset\fP     Offset in pattern where error was found
+  \fItableptr\fP      Pointer to character tables, or NULL to
+                  use the built-in default
+.sp
+The option bits are:
+.sp
+  PCRE_ANCHORED           Force pattern anchoring
+  PCRE_AUTO_CALLOUT       Compile automatic callouts
+  PCRE_BSR_ANYCRLF        \eR matches only CR, LF, or CRLF
+  PCRE_BSR_UNICODE        \eR matches all Unicode line endings
+  PCRE_CASELESS           Do caseless matching
+  PCRE_DOLLAR_ENDONLY     $ not to match newline at end
+  PCRE_DOTALL             . matches anything including NL
+  PCRE_DUPNAMES           Allow duplicate names for subpatterns
+  PCRE_EXTENDED           Ignore white space and # comments
+  PCRE_EXTRA              PCRE extra features
+                            (not much use currently)
+  PCRE_FIRSTLINE          Force matching to be before newline
+  PCRE_JAVASCRIPT_COMPAT  JavaScript compatibility
+  PCRE_MULTILINE          ^ and $ match newlines within data
+  PCRE_NEVER_UTF          Lock out UTF, e.g. via (*UTF)
+  PCRE_NEWLINE_ANY        Recognize any Unicode newline sequence
+  PCRE_NEWLINE_ANYCRLF    Recognize CR, LF, and CRLF as newline
+                            sequences
+  PCRE_NEWLINE_CR         Set CR as the newline sequence
+  PCRE_NEWLINE_CRLF       Set CRLF as the newline sequence
+  PCRE_NEWLINE_LF         Set LF as the newline sequence
+  PCRE_NO_AUTO_CAPTURE    Disable numbered capturing paren-
+                            theses (named ones available)
+  PCRE_NO_AUTO_POSSESS    Disable auto-possessification
+  PCRE_NO_START_OPTIMIZE  Disable match-time start optimizations
+  PCRE_NO_UTF16_CHECK     Do not check the pattern for UTF-16
+                            validity (only relevant if
+                            PCRE_UTF16 is set)
+  PCRE_NO_UTF32_CHECK     Do not check the pattern for UTF-32
+                            validity (only relevant if
+                            PCRE_UTF32 is set)
+  PCRE_NO_UTF8_CHECK      Do not check the pattern for UTF-8
+                            validity (only relevant if
+                            PCRE_UTF8 is set)
+  PCRE_UCP                Use Unicode properties for \ed, \ew, etc.
+  PCRE_UNGREEDY           Invert greediness of quantifiers
+  PCRE_UTF16              Run in \fBpcre16_compile()\fP UTF-16 mode
+  PCRE_UTF32              Run in \fBpcre32_compile()\fP UTF-32 mode
+  PCRE_UTF8               Run in \fBpcre_compile()\fP UTF-8 mode
+.sp
+PCRE must be built with UTF support in order to use PCRE_UTF8/16/32 and
+PCRE_NO_UTF8/16/32_CHECK, and with UCP support if PCRE_UCP is used.
+.P
+The yield of the function is a pointer to a private data structure that
+contains the compiled pattern, or NULL if an error was detected. Note that
+compiling regular expressions with one version of PCRE for use with a different
+version is not guaranteed to work and may cause crashes.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_compile2.3 b/doc/pcre_compile2.3
new file mode 100644
index 0000000..3774201
--- /dev/null
+++ b/doc/pcre_compile2.3
@@ -0,0 +1,101 @@
+.TH PCRE_COMPILE2 3 "01 October 2013" "PCRE 8.34"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
+.B "     int *\fIerrorcodeptr\fP,"
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre16 *pcre16_compile2(PCRE_SPTR16 \fIpattern\fP, int \fIoptions\fP,
+.B "     int *\fIerrorcodeptr\fP,"
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre32 *pcre32_compile2(PCRE_SPTR32 \fIpattern\fP, int \fIoptions\fP,
+.B "     int *\fIerrorcodeptr\fP,£
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function compiles a regular expression into an internal form. It is the
+same as \fBpcre[16|32]_compile()\fP, except for the addition of the
+\fIerrorcodeptr\fP argument. The arguments are:
+.
+.sp
+  \fIpattern\fP       A zero-terminated string containing the
+                  regular expression to be compiled
+  \fIoptions\fP       Zero or more option bits
+  \fIerrorcodeptr\fP  Where to put an error code
+  \fIerrptr\fP        Where to put an error message
+  \fIerroffset\fP     Offset in pattern where error was found
+  \fItableptr\fP      Pointer to character tables, or NULL to
+                  use the built-in default
+.sp
+The option bits are:
+.sp
+  PCRE_ANCHORED           Force pattern anchoring
+  PCRE_AUTO_CALLOUT       Compile automatic callouts
+  PCRE_BSR_ANYCRLF        \eR matches only CR, LF, or CRLF
+  PCRE_BSR_UNICODE        \eR matches all Unicode line endings
+  PCRE_CASELESS           Do caseless matching
+  PCRE_DOLLAR_ENDONLY     $ not to match newline at end
+  PCRE_DOTALL             . matches anything including NL
+  PCRE_DUPNAMES           Allow duplicate names for subpatterns
+  PCRE_EXTENDED           Ignore white space and # comments
+  PCRE_EXTRA              PCRE extra features
+                            (not much use currently)
+  PCRE_FIRSTLINE          Force matching to be before newline
+  PCRE_JAVASCRIPT_COMPAT  JavaScript compatibility
+  PCRE_MULTILINE          ^ and $ match newlines within data
+  PCRE_NEVER_UTF          Lock out UTF, e.g. via (*UTF)
+  PCRE_NEWLINE_ANY        Recognize any Unicode newline sequence
+  PCRE_NEWLINE_ANYCRLF    Recognize CR, LF, and CRLF as newline
+                            sequences
+  PCRE_NEWLINE_CR         Set CR as the newline sequence
+  PCRE_NEWLINE_CRLF       Set CRLF as the newline sequence
+  PCRE_NEWLINE_LF         Set LF as the newline sequence
+  PCRE_NO_AUTO_CAPTURE    Disable numbered capturing paren-
+                            theses (named ones available)
+  PCRE_NO_AUTO_POSSESS    Disable auto-possessification
+  PCRE_NO_START_OPTIMIZE  Disable match-time start optimizations
+  PCRE_NO_UTF16_CHECK     Do not check the pattern for UTF-16
+                            validity (only relevant if
+                            PCRE_UTF16 is set)
+  PCRE_NO_UTF32_CHECK     Do not check the pattern for UTF-32
+                            validity (only relevant if
+                            PCRE_UTF32 is set)
+  PCRE_NO_UTF8_CHECK      Do not check the pattern for UTF-8
+                            validity (only relevant if
+                            PCRE_UTF8 is set)
+  PCRE_UCP                Use Unicode properties for \ed, \ew, etc.
+  PCRE_UNGREEDY           Invert greediness of quantifiers
+  PCRE_UTF16              Run \fBpcre16_compile()\fP in UTF-16 mode
+  PCRE_UTF32              Run \fBpcre32_compile()\fP in UTF-32 mode
+  PCRE_UTF8               Run \fBpcre_compile()\fP in UTF-8 mode
+.sp
+PCRE must be built with UTF support in order to use PCRE_UTF8/16/32 and
+PCRE_NO_UTF8/16/32_CHECK, and with UCP support if PCRE_UCP is used.
+.P
+The yield of the function is a pointer to a private data structure that
+contains the compiled pattern, or NULL if an error was detected. Note that
+compiling regular expressions with one version of PCRE for use with a different
+version is not guaranteed to work and may cause crashes.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_config.3 b/doc/pcre_config.3
new file mode 100644
index 0000000..d3de14b
--- /dev/null
+++ b/doc/pcre_config.3
@@ -0,0 +1,77 @@
+.TH PCRE_CONFIG 3 "05 November 2013" "PCRE 8.34"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.SM
+.B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
+.PP
+.B int pcre16_config(int \fIwhat\fP, void *\fIwhere\fP);
+.PP
+.B int pcre32_config(int \fIwhat\fP, void *\fIwhere\fP);
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function makes it possible for a client program to find out which optional
+features are available in the version of the PCRE library it is using. The
+arguments are as follows:
+.sp
+  \fIwhat\fP     A code specifying what information is required
+  \fIwhere\fP    Points to where to put the data
+.sp
+The \fIwhere\fP argument must point to an integer variable, except for
+PCRE_CONFIG_MATCH_LIMIT and PCRE_CONFIG_MATCH_LIMIT_RECURSION, when it must
+point to an unsigned long integer. The available codes are:
+.sp
+  PCRE_CONFIG_JIT           Availability of just-in-time compiler
+                              support (1=yes 0=no)
+  PCRE_CONFIG_JITTARGET     String containing information about the
+                              target architecture for the JIT compiler,
+                              or NULL if there is no JIT support
+  PCRE_CONFIG_LINK_SIZE     Internal link size: 2, 3, or 4
+  PCRE_CONFIG_PARENS_LIMIT  Parentheses nesting limit
+  PCRE_CONFIG_MATCH_LIMIT   Internal resource limit
+  PCRE_CONFIG_MATCH_LIMIT_RECURSION
+                            Internal recursion depth limit
+  PCRE_CONFIG_NEWLINE       Value of the default newline sequence:
+                                13 (0x000d)    for CR
+                                10 (0x000a)    for LF
+                              3338 (0x0d0a)    for CRLF
+                                -2             for ANYCRLF
+                                -1             for ANY
+  PCRE_CONFIG_BSR           Indicates what \eR matches by default:
+                                 0             all Unicode line endings
+                                 1             CR, LF, or CRLF only
+  PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
+                            Threshold of return slots, above which
+                              \fBmalloc()\fP is used by the POSIX API
+  PCRE_CONFIG_STACKRECURSE  Recursion implementation (1=stack 0=heap)
+  PCRE_CONFIG_UTF16         Availability of UTF-16 support (1=yes
+                               0=no); option for \fBpcre16_config()\fP
+  PCRE_CONFIG_UTF32         Availability of UTF-32 support (1=yes
+                               0=no); option for \fBpcre32_config()\fP
+  PCRE_CONFIG_UTF8          Availability of UTF-8 support (1=yes 0=no);
+                              option for \fBpcre_config()\fP
+  PCRE_CONFIG_UNICODE_PROPERTIES
+                            Availability of Unicode property support
+                              (1=yes 0=no)
+.sp
+The function yields 0 on success or PCRE_ERROR_BADOPTION otherwise. That error
+is also given if PCRE_CONFIG_UTF16 or PCRE_CONFIG_UTF32 is passed to
+\fBpcre_config()\fP, if PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF32 is passed to
+\fBpcre16_config()\fP, or if PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF16 is passed to
+\fBpcre32_config()\fP.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_copy_named_substring.3 b/doc/pcre_copy_named_substring.3
new file mode 100644
index 0000000..52582ae
--- /dev/null
+++ b/doc/pcre_copy_named_substring.3
@@ -0,0 +1,51 @@
+.TH PCRE_COPY_NAMED_SUBSTRING 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_copy_named_substring(const pcre *\fIcode\fP,
+.B "     const char *\fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, const char *\fIstringname\fP,"
+.B "     char *\fIbuffer\fP, int \fIbuffersize\fP);"
+.sp
+.B int pcre16_copy_named_substring(const pcre16 *\fIcode\fP,
+.B "     PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, PCRE_SPTR16 \fIstringname\fP,"
+.B "     PCRE_UCHAR16 *\fIbuffer\fP, int \fIbuffersize\fP);"
+.sp
+.B int pcre32_copy_named_substring(const pcre32 *\fIcode\fP,
+.B "     PCRE_SPTR32 \fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, PCRE_SPTR32 \fIstringname\fP,"
+.B "     PCRE_UCHAR32 *\fIbuffer\fP, int \fIbuffersize\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This is a convenience function for extracting a captured substring, identified
+by name, into a given buffer. The arguments are:
+.sp
+  \fIcode\fP          Pattern that was successfully matched
+  \fIsubject\fP       Subject that has been successfully matched
+  \fIovector\fP       Offset vector that \fBpcre[16|32]_exec()\fP used
+  \fIstringcount\fP   Value returned by \fBpcre[16|32]_exec()\fP
+  \fIstringname\fP    Name of the required substring
+  \fIbuffer\fP        Buffer to receive the string
+  \fIbuffersize\fP    Size of buffer
+.sp
+The yield is the length of the substring, PCRE_ERROR_NOMEMORY if the buffer was
+too small, or PCRE_ERROR_NOSUBSTRING if the string name is invalid.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_copy_substring.3 b/doc/pcre_copy_substring.3
new file mode 100644
index 0000000..83af6e8
--- /dev/null
+++ b/doc/pcre_copy_substring.3
@@ -0,0 +1,47 @@
+.TH PCRE_COPY_SUBSTRING 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,"
+.B "     int \fIbuffersize\fP);"
+.sp
+.B int pcre16_copy_substring(PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP, PCRE_UCHAR16 *\fIbuffer\fP,"
+.B "     int \fIbuffersize\fP);"
+.sp
+.B int pcre32_copy_substring(PCRE_SPTR32 \fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP, PCRE_UCHAR32 *\fIbuffer\fP,"
+.B "     int \fIbuffersize\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This is a convenience function for extracting a captured substring into a given
+buffer. The arguments are:
+.sp
+  \fIsubject\fP       Subject that has been successfully matched
+  \fIovector\fP       Offset vector that \fBpcre[16|32]_exec()\fP used
+  \fIstringcount\fP   Value returned by \fBpcre[16|32]_exec()\fP
+  \fIstringnumber\fP  Number of the required substring
+  \fIbuffer\fP        Buffer to receive the string
+  \fIbuffersize\fP    Size of buffer
+.sp
+The yield is the length of the string, PCRE_ERROR_NOMEMORY if the buffer was
+too small, or PCRE_ERROR_NOSUBSTRING if the string number is invalid.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_dfa_exec.3 b/doc/pcre_dfa_exec.3
new file mode 100644
index 0000000..39c2e83
--- /dev/null
+++ b/doc/pcre_dfa_exec.3
@@ -0,0 +1,118 @@
+.TH PCRE_DFA_EXEC 3 "12 May 2013" "PCRE 8.33"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     const char *\fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     int *\fIworkspace\fP, int \fIwscount\fP);"
+.sp
+.B int pcre16_dfa_exec(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
+.B "     PCRE_SPTR16 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     int *\fIworkspace\fP, int \fIwscount\fP);"
+.sp
+.B int pcre32_dfa_exec(const pcre32 *\fIcode\fP, "const pcre32_extra *\fIextra\fP,"
+.B "     PCRE_SPTR32 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     int *\fIworkspace\fP, int \fIwscount\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function matches a compiled regular expression against a given subject
+string, using an alternative matching algorithm that scans the subject string
+just once (\fInot\fP Perl-compatible). Note that the main, Perl-compatible,
+matching function is \fBpcre[16|32]_exec()\fP. The arguments for this function
+are:
+.sp
+  \fIcode\fP         Points to the compiled pattern
+  \fIextra\fP        Points to an associated \fBpcre[16|32]_extra\fP structure,
+                 or is NULL
+  \fIsubject\fP      Points to the subject string
+  \fIlength\fP       Length of the subject string
+  \fIstartoffset\fP  Offset in the subject at which to start matching
+  \fIoptions\fP      Option bits
+  \fIovector\fP      Points to a vector of ints for result offsets
+  \fIovecsize\fP     Number of elements in the vector
+  \fIworkspace\fP    Points to a vector of ints used as working space
+  \fIwscount\fP      Number of elements in the vector
+.sp
+The units for \fIlength\fP and \fIstartoffset\fP are bytes for
+\fBpcre_exec()\fP, 16-bit data items for \fBpcre16_exec()\fP, and 32-bit items
+for \fBpcre32_exec()\fP. The options are:
+.sp
+  PCRE_ANCHORED          Match only at the first position
+  PCRE_BSR_ANYCRLF       \eR matches only CR, LF, or CRLF
+  PCRE_BSR_UNICODE       \eR matches all Unicode line endings
+  PCRE_NEWLINE_ANY       Recognize any Unicode newline sequence
+  PCRE_NEWLINE_ANYCRLF   Recognize CR, LF, & CRLF as newline sequences
+  PCRE_NEWLINE_CR        Recognize CR as the only newline sequence
+  PCRE_NEWLINE_CRLF      Recognize CRLF as the only newline sequence
+  PCRE_NEWLINE_LF        Recognize LF as the only newline sequence
+  PCRE_NOTBOL            Subject is not the beginning of a line
+  PCRE_NOTEOL            Subject is not the end of a line
+  PCRE_NOTEMPTY          An empty string is not a valid match
+  PCRE_NOTEMPTY_ATSTART  An empty string at the start of the subject
+                           is not a valid match
+  PCRE_NO_START_OPTIMIZE Do not do "start-match" optimizations
+  PCRE_NO_UTF16_CHECK    Do not check the subject for UTF-16
+                           validity (only relevant if PCRE_UTF16
+                           was set at compile time)
+  PCRE_NO_UTF32_CHECK    Do not check the subject for UTF-32
+                           validity (only relevant if PCRE_UTF32
+                           was set at compile time)
+  PCRE_NO_UTF8_CHECK     Do not check the subject for UTF-8
+                           validity (only relevant if PCRE_UTF8
+                           was set at compile time)
+  PCRE_PARTIAL           ) Return PCRE_ERROR_PARTIAL for a partial
+  PCRE_PARTIAL_SOFT      )   match if no full matches are found
+  PCRE_PARTIAL_HARD      Return PCRE_ERROR_PARTIAL for a partial match
+                           even if there is a full match as well
+  PCRE_DFA_SHORTEST      Return only the shortest match
+  PCRE_DFA_RESTART       Restart after a partial match
+.sp
+There are restrictions on what may appear in a pattern when using this matching
+function. Details are given in the
+.\" HREF
+\fBpcrematching\fP
+.\"
+documentation. For details of partial matching, see the
+.\" HREF
+\fBpcrepartial\fP
+.\"
+page.
+.P
+A \fBpcre[16|32]_extra\fP structure contains the following fields:
+.sp
+  \fIflags\fP            Bits indicating which fields are set
+  \fIstudy_data\fP       Opaque data from \fBpcre[16|32]_study()\fP
+  \fImatch_limit\fP      Limit on internal resource use
+  \fImatch_limit_recursion\fP  Limit on internal recursion depth
+  \fIcallout_data\fP     Opaque data passed back to callouts
+  \fItables\fP           Points to character tables or is NULL
+  \fImark\fP             For passing back a *MARK pointer
+  \fIexecutable_jit\fP   Opaque data from JIT compilation
+.sp
+The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT,
+PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA,
+PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT. For this
+matching function, the \fImatch_limit\fP and \fImatch_limit_recursion\fP fields
+are not used, and must not be set. The PCRE_EXTRA_EXECUTABLE_JIT flag and
+the corresponding variable are ignored.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_exec.3 b/doc/pcre_exec.3
new file mode 100644
index 0000000..4686bd6
--- /dev/null
+++ b/doc/pcre_exec.3
@@ -0,0 +1,99 @@
+.TH PCRE_EXEC 3 "12 May 2013" "PCRE 8.33"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     const char *\fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);"
+.sp
+.B int pcre16_exec(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
+.B "     PCRE_SPTR16 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);"
+.sp
+.B int pcre32_exec(const pcre32 *\fIcode\fP, "const pcre32_extra *\fIextra\fP,"
+.B "     PCRE_SPTR32 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function matches a compiled regular expression against a given subject
+string, using a matching algorithm that is similar to Perl's. It returns
+offsets to captured substrings. Its arguments are:
+.sp
+  \fIcode\fP         Points to the compiled pattern
+  \fIextra\fP        Points to an associated \fBpcre[16|32]_extra\fP structure,
+                 or is NULL
+  \fIsubject\fP      Points to the subject string
+  \fIlength\fP       Length of the subject string
+  \fIstartoffset\fP  Offset in the subject at which to start matching
+  \fIoptions\fP      Option bits
+  \fIovector\fP      Points to a vector of ints for result offsets
+  \fIovecsize\fP     Number of elements in the vector (a multiple of 3)
+.sp
+The units for \fIlength\fP and \fIstartoffset\fP are bytes for
+\fBpcre_exec()\fP, 16-bit data items for \fBpcre16_exec()\fP, and 32-bit items
+for \fBpcre32_exec()\fP. The options are:
+.sp
+  PCRE_ANCHORED          Match only at the first position
+  PCRE_BSR_ANYCRLF       \eR matches only CR, LF, or CRLF
+  PCRE_BSR_UNICODE       \eR matches all Unicode line endings
+  PCRE_NEWLINE_ANY       Recognize any Unicode newline sequence
+  PCRE_NEWLINE_ANYCRLF   Recognize CR, LF, & CRLF as newline sequences
+  PCRE_NEWLINE_CR        Recognize CR as the only newline sequence
+  PCRE_NEWLINE_CRLF      Recognize CRLF as the only newline sequence
+  PCRE_NEWLINE_LF        Recognize LF as the only newline sequence
+  PCRE_NOTBOL            Subject string is not the beginning of a line
+  PCRE_NOTEOL            Subject string is not the end of a line
+  PCRE_NOTEMPTY          An empty string is not a valid match
+  PCRE_NOTEMPTY_ATSTART  An empty string at the start of the subject
+                           is not a valid match
+  PCRE_NO_START_OPTIMIZE Do not do "start-match" optimizations
+  PCRE_NO_UTF16_CHECK    Do not check the subject for UTF-16
+                           validity (only relevant if PCRE_UTF16
+                           was set at compile time)
+  PCRE_NO_UTF32_CHECK    Do not check the subject for UTF-32
+                           validity (only relevant if PCRE_UTF32
+                           was set at compile time)
+  PCRE_NO_UTF8_CHECK     Do not check the subject for UTF-8
+                           validity (only relevant if PCRE_UTF8
+                           was set at compile time)
+  PCRE_PARTIAL           ) Return PCRE_ERROR_PARTIAL for a partial
+  PCRE_PARTIAL_SOFT      )   match if no full matches are found
+  PCRE_PARTIAL_HARD      Return PCRE_ERROR_PARTIAL for a partial match
+                           if that is found before a full match
+.sp
+For details of partial matching, see the
+.\" HREF
+\fBpcrepartial\fP
+.\"
+page. A \fBpcre_extra\fP structure contains the following fields:
+.sp
+  \fIflags\fP            Bits indicating which fields are set
+  \fIstudy_data\fP       Opaque data from \fBpcre[16|32]_study()\fP
+  \fImatch_limit\fP      Limit on internal resource use
+  \fImatch_limit_recursion\fP  Limit on internal recursion depth
+  \fIcallout_data\fP     Opaque data passed back to callouts
+  \fItables\fP           Points to character tables or is NULL
+  \fImark\fP             For passing back a *MARK pointer
+  \fIexecutable_jit\fP   Opaque data from JIT compilation
+.sp
+The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT,
+PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA,
+PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_free_study.3 b/doc/pcre_free_study.3
new file mode 100644
index 0000000..8826b73
--- /dev/null
+++ b/doc/pcre_free_study.3
@@ -0,0 +1,31 @@
+.TH PCRE_FREE_STUDY 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.SM
+.B void pcre_free_study(pcre_extra *\fIextra\fP);
+.PP
+.B void pcre16_free_study(pcre16_extra *\fIextra\fP);
+.PP
+.B void pcre32_free_study(pcre32_extra *\fIextra\fP);
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function is used to free the memory used for the data generated by a call
+to \fBpcre[16|32]_study()\fP when it is no longer needed. The argument must be the
+result of such a call.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_free_substring.3 b/doc/pcre_free_substring.3
new file mode 100644
index 0000000..88c0401
--- /dev/null
+++ b/doc/pcre_free_substring.3
@@ -0,0 +1,31 @@
+.TH PCRE_FREE_SUBSTRING 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.SM
+.B void pcre_free_substring(const char *\fIstringptr\fP);
+.PP
+.B void pcre16_free_substring(PCRE_SPTR16 \fIstringptr\fP);
+.PP
+.B void pcre32_free_substring(PCRE_SPTR32 \fIstringptr\fP);
+.
+.SH DESCRIPTION
+.rs
+.sp
+This is a convenience function for freeing the store obtained by a previous
+call to \fBpcre[16|32]_get_substring()\fP or \fBpcre[16|32]_get_named_substring()\fP.
+Its only argument is a pointer to the string.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_free_substring_list.3 b/doc/pcre_free_substring_list.3
new file mode 100644
index 0000000..248b4bd
--- /dev/null
+++ b/doc/pcre_free_substring_list.3
@@ -0,0 +1,31 @@
+.TH PCRE_FREE_SUBSTRING_LIST 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.SM
+.B void pcre_free_substring_list(const char **\fIstringptr\fP);
+.PP
+.B void pcre16_free_substring_list(PCRE_SPTR16 *\fIstringptr\fP);
+.PP
+.B void pcre32_free_substring_list(PCRE_SPTR32 *\fIstringptr\fP);
+.
+.SH DESCRIPTION
+.rs
+.sp
+This is a convenience function for freeing the store obtained by a previous
+call to \fBpcre[16|32]_get_substring_list()\fP. Its only argument is a pointer to
+the list of string pointers.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_fullinfo.3 b/doc/pcre_fullinfo.3
new file mode 100644
index 0000000..01e2e92
--- /dev/null
+++ b/doc/pcre_fullinfo.3
@@ -0,0 +1,93 @@
+.TH PCRE_FULLINFO 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     int \fIwhat\fP, void *\fIwhere\fP);"
+.sp
+.B int pcre16_fullinfo(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
+.B "     int \fIwhat\fP, void *\fIwhere\fP);"
+.sp
+.B int pcre32_fullinfo(const pcre32 *\fIcode\fP, "const pcre32_extra *\fIextra\fP,"
+.B "     int \fIwhat\fP, void *\fIwhere\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function returns information about a compiled pattern. Its arguments are:
+.sp
+  \fIcode\fP                      Compiled regular expression
+  \fIextra\fP                     Result of \fBpcre[16|32]_study()\fP or NULL
+  \fIwhat\fP                      What information is required
+  \fIwhere\fP                     Where to put the information
+.sp
+The following information is available:
+.sp
+  PCRE_INFO_BACKREFMAX      Number of highest back reference
+  PCRE_INFO_CAPTURECOUNT    Number of capturing subpatterns
+  PCRE_INFO_DEFAULT_TABLES  Pointer to default tables
+  PCRE_INFO_FIRSTBYTE       Fixed first data unit for a match, or
+                              -1 for start of string
+                                 or after newline, or
+                              -2 otherwise
+  PCRE_INFO_FIRSTTABLE      Table of first data units (after studying)
+  PCRE_INFO_HASCRORLF       Return 1 if explicit CR or LF matches exist
+  PCRE_INFO_JCHANGED        Return 1 if (?J) or (?-J) was used
+  PCRE_INFO_JIT             Return 1 after successful JIT compilation
+  PCRE_INFO_JITSIZE         Size of JIT compiled code
+  PCRE_INFO_LASTLITERAL     Literal last data unit required
+  PCRE_INFO_MINLENGTH       Lower bound length of matching strings
+  PCRE_INFO_NAMECOUNT       Number of named subpatterns
+  PCRE_INFO_NAMEENTRYSIZE   Size of name table entry
+  PCRE_INFO_NAMETABLE       Pointer to name table
+  PCRE_INFO_OKPARTIAL       Return 1 if partial matching can be tried
+                              (always returns 1 after release 8.00)
+  PCRE_INFO_OPTIONS         Option bits used for compilation
+  PCRE_INFO_SIZE            Size of compiled pattern
+  PCRE_INFO_STUDYSIZE       Size of study data
+  PCRE_INFO_FIRSTCHARACTER      Fixed first data unit for a match
+  PCRE_INFO_FIRSTCHARACTERFLAGS Returns
+                                  1 if there is a first data character set, which can
+                                    then be retrieved using PCRE_INFO_FIRSTCHARACTER,
+                                  2 if the first character is at the start of the data
+                                    string or after a newline, and
+                                  0 otherwise
+  PCRE_INFO_REQUIREDCHAR      Literal last data unit required
+  PCRE_INFO_REQUIREDCHARFLAGS Returns 1 if the last data character is set (which can then
+                              be retrieved using PCRE_INFO_REQUIREDCHAR); 0 otherwise
+.sp
+The \fIwhere\fP argument must point to an integer variable, except for the
+following \fIwhat\fP values:
+.sp
+  PCRE_INFO_DEFAULT_TABLES  const unsigned char *
+  PCRE_INFO_FIRSTTABLE      const unsigned char *
+  PCRE_INFO_NAMETABLE       PCRE_SPTR16           (16-bit library)
+  PCRE_INFO_NAMETABLE       PCRE_SPTR32           (32-bit library)
+  PCRE_INFO_NAMETABLE       const unsigned char * (8-bit library)
+  PCRE_INFO_OPTIONS         unsigned long int
+  PCRE_INFO_SIZE            size_t
+  PCRE_INFO_FIRSTCHARACTER  uint32_t
+  PCRE_INFO_REQUIREDCHAR    uint32_t
+.sp
+The yield of the function is zero on success or:
+.sp
+  PCRE_ERROR_NULL           the argument \fIcode\fP was NULL
+                            the argument \fIwhere\fP was NULL
+  PCRE_ERROR_BADMAGIC       the "magic number" was not found
+  PCRE_ERROR_BADOPTION      the value of \fIwhat\fP was invalid
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_get_named_substring.3 b/doc/pcre_get_named_substring.3
new file mode 100644
index 0000000..84d4ee7
--- /dev/null
+++ b/doc/pcre_get_named_substring.3
@@ -0,0 +1,54 @@
+.TH PCRE_GET_NAMED_SUBSTRING 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_get_named_substring(const pcre *\fIcode\fP,
+.B "     const char *\fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, const char *\fIstringname\fP,"
+.B "     const char **\fIstringptr\fP);"
+.sp
+.B int pcre16_get_named_substring(const pcre16 *\fIcode\fP,
+.B "     PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, PCRE_SPTR16 \fIstringname\fP,"
+.B "     PCRE_SPTR16 *\fIstringptr\fP);"
+.sp
+.B int pcre32_get_named_substring(const pcre32 *\fIcode\fP,
+.B "     PCRE_SPTR32 \fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, PCRE_SPTR32 \fIstringname\fP,"
+.B "     PCRE_SPTR32 *\fIstringptr\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This is a convenience function for extracting a captured substring by name. The
+arguments are:
+.sp
+  \fIcode\fP          Compiled pattern
+  \fIsubject\fP       Subject that has been successfully matched
+  \fIovector\fP       Offset vector that \fBpcre[16|32]_exec()\fP used
+  \fIstringcount\fP   Value returned by \fBpcre[16|32]_exec()\fP
+  \fIstringname\fP    Name of the required substring
+  \fIstringptr\fP     Where to put the string pointer
+.sp
+The memory in which the substring is placed is obtained by calling
+\fBpcre[16|32]_malloc()\fP. The convenience function
+\fBpcre[16|32]_free_substring()\fP can be used to free it when it is no longer
+needed. The yield of the function is the length of the extracted substring,
+PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or
+PCRE_ERROR_NOSUBSTRING if the string name is invalid.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_get_stringnumber.3 b/doc/pcre_get_stringnumber.3
new file mode 100644
index 0000000..9fc5291
--- /dev/null
+++ b/doc/pcre_get_stringnumber.3
@@ -0,0 +1,43 @@
+.TH PCRE_GET_STRINGNUMBER 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_get_stringnumber(const pcre *\fIcode\fP,
+.B "     const char *\fIname\fP);"
+.sp
+.B int pcre16_get_stringnumber(const pcre16 *\fIcode\fP,
+.B "     PCRE_SPTR16 \fIname\fP);"
+.sp
+.B int pcre32_get_stringnumber(const pcre32 *\fIcode\fP,
+.B "     PCRE_SPTR32 \fIname\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This convenience function finds the number of a named substring capturing
+parenthesis in a compiled pattern. Its arguments are:
+.sp
+  \fIcode\fP    Compiled regular expression
+  \fIname\fP    Name whose number is required
+.sp
+The yield of the function is the number of the parenthesis if the name is
+found, or PCRE_ERROR_NOSUBSTRING otherwise. When duplicate names are allowed
+(PCRE_DUPNAMES is set), it is not defined which of the numbers is returned by
+\fBpcre[16|32]_get_stringnumber()\fP. You can obtain the complete list by calling
+\fBpcre[16|32]_get_stringtable_entries()\fP.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_get_stringtable_entries.3 b/doc/pcre_get_stringtable_entries.3
new file mode 100644
index 0000000..5c58c90
--- /dev/null
+++ b/doc/pcre_get_stringtable_entries.3
@@ -0,0 +1,46 @@
+.TH PCRE_GET_STRINGTABLE_ENTRIES 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
+.B "     const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);"
+.sp
+.B int pcre16_get_stringtable_entries(const pcre16 *\fIcode\fP,
+.B "     PCRE_SPTR16 \fIname\fP, PCRE_UCHAR16 **\fIfirst\fP, PCRE_UCHAR16 **\fIlast\fP);"
+.sp
+.B int pcre32_get_stringtable_entries(const pcre32 *\fIcode\fP,
+.B "     PCRE_SPTR32 \fIname\fP, PCRE_UCHAR32 **\fIfirst\fP, PCRE_UCHAR32 **\fIlast\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This convenience function finds, for a compiled pattern, the first and last
+entries for a given name in the table that translates capturing parenthesis
+names into numbers. When names are required to be unique (PCRE_DUPNAMES is
+\fInot\fP set), it is usually easier to use \fBpcre[16|32]_get_stringnumber()\fP
+instead.
+.sp
+  \fIcode\fP    Compiled regular expression
+  \fIname\fP    Name whose entries required
+  \fIfirst\fP   Where to return a pointer to the first entry
+  \fIlast\fP    Where to return a pointer to the last entry
+.sp
+The yield of the function is the length of each entry, or
+PCRE_ERROR_NOSUBSTRING if none are found.
+.P
+There is a complete description of the PCRE native API, including the format of
+the table entries, in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page, and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_get_substring.3 b/doc/pcre_get_substring.3
new file mode 100644
index 0000000..1e62b2c
--- /dev/null
+++ b/doc/pcre_get_substring.3
@@ -0,0 +1,50 @@
+.TH PCRE_GET_SUBSTRING 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP,"
+.B "     const char **\fIstringptr\fP);"
+.sp
+.B int pcre16_get_substring(PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP,"
+.B "     PCRE_SPTR16 *\fIstringptr\fP);"
+.sp
+.B int pcre32_get_substring(PCRE_SPTR32 \fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP,"
+.B "     PCRE_SPTR32 *\fIstringptr\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This is a convenience function for extracting a captured substring. The
+arguments are:
+.sp
+  \fIsubject\fP       Subject that has been successfully matched
+  \fIovector\fP       Offset vector that \fBpcre[16|32]_exec()\fP used
+  \fIstringcount\fP   Value returned by \fBpcre[16|32]_exec()\fP
+  \fIstringnumber\fP  Number of the required substring
+  \fIstringptr\fP     Where to put the string pointer
+.sp
+The memory in which the substring is placed is obtained by calling
+\fBpcre[16|32]_malloc()\fP. The convenience function
+\fBpcre[16|32]_free_substring()\fP can be used to free it when it is no longer
+needed. The yield of the function is the length of the substring,
+PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or
+PCRE_ERROR_NOSUBSTRING if the string number is invalid.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_get_substring_list.3 b/doc/pcre_get_substring_list.3
new file mode 100644
index 0000000..511a4a3
--- /dev/null
+++ b/doc/pcre_get_substring_list.3
@@ -0,0 +1,47 @@
+.TH PCRE_GET_SUBSTRING_LIST 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_get_substring_list(const char *\fIsubject\fP,
+.B "     int *\fIovector\fP, int \fIstringcount\fP, const char ***\fIlistptr\fP);"
+.sp
+.B int pcre16_get_substring_list(PCRE_SPTR16 \fIsubject\fP,
+.B "     int *\fIovector\fP, int \fIstringcount\fP, PCRE_SPTR16 **\fIlistptr\fP);"
+.sp
+.B int pcre32_get_substring_list(PCRE_SPTR32 \fIsubject\fP,
+.B "     int *\fIovector\fP, int \fIstringcount\fP, PCRE_SPTR32 **\fIlistptr\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This is a convenience function for extracting a list of all the captured
+substrings. The arguments are:
+.sp
+  \fIsubject\fP       Subject that has been successfully matched
+  \fIovector\fP       Offset vector that \fBpcre[16|32]_exec\fP used
+  \fIstringcount\fP   Value returned by \fBpcre[16|32]_exec\fP
+  \fIlistptr\fP       Where to put a pointer to the list
+.sp
+The memory in which the substrings and the list are placed is obtained by
+calling \fBpcre[16|32]_malloc()\fP. The convenience function
+\fBpcre[16|32]_free_substring_list()\fP can be used to free it when it is no
+longer needed. A pointer to a list of pointers is put in the variable whose
+address is in \fIlistptr\fP. The list is terminated by a NULL pointer. The
+yield of the function is zero on success or PCRE_ERROR_NOMEMORY if sufficient
+memory could not be obtained.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_jit_exec.3 b/doc/pcre_jit_exec.3
new file mode 100644
index 0000000..ba85168
--- /dev/null
+++ b/doc/pcre_jit_exec.3
@@ -0,0 +1,96 @@
+.TH PCRE_EXEC 3 "31 October 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_jit_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     const char *\fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     pcre_jit_stack *\fIjstack\fP);"
+.sp
+.B int pcre16_jit_exec(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
+.B "     PCRE_SPTR16 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     pcre_jit_stack *\fIjstack\fP);"
+.sp
+.B int pcre32_jit_exec(const pcre32 *\fIcode\fP, "const pcre32_extra *\fIextra\fP,"
+.B "     PCRE_SPTR32 \fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     pcre_jit_stack *\fIjstack\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function matches a compiled regular expression that has been successfully
+studied with one of the JIT options against a given subject string, using a
+matching algorithm that is similar to Perl's. It is a "fast path" interface to
+JIT, and it bypasses some of the sanity checks that \fBpcre_exec()\fP applies.
+It returns offsets to captured substrings. Its arguments are:
+.sp
+  \fIcode\fP         Points to the compiled pattern
+  \fIextra\fP        Points to an associated \fBpcre[16|32]_extra\fP structure,
+                 or is NULL
+  \fIsubject\fP      Points to the subject string
+  \fIlength\fP       Length of the subject string, in bytes
+  \fIstartoffset\fP  Offset in bytes in the subject at which to
+                 start matching
+  \fIoptions\fP      Option bits
+  \fIovector\fP      Points to a vector of ints for result offsets
+  \fIovecsize\fP     Number of elements in the vector (a multiple of 3)
+  \fIjstack\fP       Pointer to a JIT stack
+.sp
+The allowed options are:
+.sp
+  PCRE_NOTBOL            Subject string is not the beginning of a line
+  PCRE_NOTEOL            Subject string is not the end of a line
+  PCRE_NOTEMPTY          An empty string is not a valid match
+  PCRE_NOTEMPTY_ATSTART  An empty string at the start of the subject
+                           is not a valid match
+  PCRE_NO_UTF16_CHECK    Do not check the subject for UTF-16
+                           validity (only relevant if PCRE_UTF16
+                           was set at compile time)
+  PCRE_NO_UTF32_CHECK    Do not check the subject for UTF-32
+                           validity (only relevant if PCRE_UTF32
+                           was set at compile time)
+  PCRE_NO_UTF8_CHECK     Do not check the subject for UTF-8
+                           validity (only relevant if PCRE_UTF8
+                           was set at compile time)
+  PCRE_PARTIAL           ) Return PCRE_ERROR_PARTIAL for a partial
+  PCRE_PARTIAL_SOFT      )   match if no full matches are found
+  PCRE_PARTIAL_HARD      Return PCRE_ERROR_PARTIAL for a partial match
+                           if that is found before a full match
+.sp
+However, the PCRE_NO_UTF[8|16|32]_CHECK options have no effect, as this check
+is never applied. For details of partial matching, see the
+.\" HREF
+\fBpcrepartial\fP
+.\"
+page. A \fBpcre_extra\fP structure contains the following fields:
+.sp
+  \fIflags\fP            Bits indicating which fields are set
+  \fIstudy_data\fP       Opaque data from \fBpcre[16|32]_study()\fP
+  \fImatch_limit\fP      Limit on internal resource use
+  \fImatch_limit_recursion\fP  Limit on internal recursion depth
+  \fIcallout_data\fP     Opaque data passed back to callouts
+  \fItables\fP           Points to character tables or is NULL
+  \fImark\fP             For passing back a *MARK pointer
+  \fIexecutable_jit\fP   Opaque data from JIT compilation
+.sp
+The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT,
+PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA,
+PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the JIT API in the
+.\" HREF
+\fBpcrejit\fP
+.\"
+page.
diff --git a/doc/pcre_jit_stack_alloc.3 b/doc/pcre_jit_stack_alloc.3
new file mode 100644
index 0000000..11c97a0
--- /dev/null
+++ b/doc/pcre_jit_stack_alloc.3
@@ -0,0 +1,43 @@
+.TH PCRE_JIT_STACK_ALLOC 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP,
+.B "     int \fImaxsize\fP);"
+.sp
+.B pcre16_jit_stack *pcre16_jit_stack_alloc(int \fIstartsize\fP,
+.B "     int \fImaxsize\fP);"
+.sp
+.B pcre32_jit_stack *pcre32_jit_stack_alloc(int \fIstartsize\fP,
+.B "     int \fImaxsize\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function is used to create a stack for use by the code compiled by the JIT
+optimization of \fBpcre[16|32]_study()\fP. The arguments are a starting size for
+the stack, and a maximum size to which it is allowed to grow. The result can be
+passed to the JIT run-time code by \fBpcre[16|32]_assign_jit_stack()\fP, or that
+function can set up a callback for obtaining a stack. A maximum stack size of
+512K to 1M should be more than enough for any pattern. For more details, see
+the
+.\" HREF
+\fBpcrejit\fP
+.\"
+page.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_jit_stack_free.3 b/doc/pcre_jit_stack_free.3
new file mode 100644
index 0000000..494724e
--- /dev/null
+++ b/doc/pcre_jit_stack_free.3
@@ -0,0 +1,35 @@
+.TH PCRE_JIT_STACK_FREE 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.SM
+.B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
+.PP
+.B void pcre16_jit_stack_free(pcre16_jit_stack *\fIstack\fP);
+.PP
+.B void pcre32_jit_stack_free(pcre32_jit_stack *\fIstack\fP);
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function is used to free a JIT stack that was created by
+\fBpcre[16|32]_jit_stack_alloc()\fP when it is no longer needed. For more details,
+see the
+.\" HREF
+\fBpcrejit\fP
+.\"
+page.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_maketables.3 b/doc/pcre_maketables.3
new file mode 100644
index 0000000..b2c3d23
--- /dev/null
+++ b/doc/pcre_maketables.3
@@ -0,0 +1,33 @@
+.TH PCRE_MAKETABLES 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.SM
+.B const unsigned char *pcre_maketables(void);
+.PP
+.B const unsigned char *pcre16_maketables(void);
+.PP
+.B const unsigned char *pcre32_maketables(void);
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function builds a set of character tables for character values less than
+256. These can be passed to \fBpcre[16|32]_compile()\fP to override PCRE's
+internal, built-in tables (which were made by \fBpcre[16|32]_maketables()\fP when
+PCRE was compiled). You might want to do this if you are using a non-standard
+locale. The function yields a pointer to the tables.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_pattern_to_host_byte_order.3 b/doc/pcre_pattern_to_host_byte_order.3
new file mode 100644
index 0000000..b0c41c3
--- /dev/null
+++ b/doc/pcre_pattern_to_host_byte_order.3
@@ -0,0 +1,44 @@
+.TH PCRE_PATTERN_TO_HOST_BYTE_ORDER 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre_pattern_to_host_byte_order(pcre *\fIcode\fP,
+.B "     pcre_extra *\fIextra\fP, const unsigned char *\fItables\fP);"
+.sp
+.B int pcre16_pattern_to_host_byte_order(pcre16 *\fIcode\fP,
+.B "     pcre16_extra *\fIextra\fP, const unsigned char *\fItables\fP);"
+.sp
+.B int pcre32_pattern_to_host_byte_order(pcre32 *\fIcode\fP,
+.B "     pcre32_extra *\fIextra\fP, const unsigned char *\fItables\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function ensures that the bytes in 2-byte and 4-byte values in a compiled
+pattern are in the correct order for the current host. It is useful when a
+pattern that has been compiled on one host is transferred to another that might
+have different endianness. The arguments are:
+.sp
+  \fIcode\fP         A compiled regular expression
+  \fIextra\fP        Points to an associated \fBpcre[16|32]_extra\fP structure,
+                 or is NULL
+  \fItables\fP       Pointer to character tables, or NULL to
+                 set the built-in default
+.sp
+The result is 0 for success, a negative PCRE_ERROR_xxx value otherwise.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_refcount.3 b/doc/pcre_refcount.3
new file mode 100644
index 0000000..45a41fe
--- /dev/null
+++ b/doc/pcre_refcount.3
@@ -0,0 +1,36 @@
+.TH PCRE_REFCOUNT 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.SM
+.B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
+.PP
+.B int pcre16_refcount(pcre16 *\fIcode\fP, int \fIadjust\fP);
+.PP
+.B int pcre32_refcount(pcre32 *\fIcode\fP, int \fIadjust\fP);
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function is used to maintain a reference count inside a data block that
+contains a compiled pattern. Its arguments are:
+.sp
+  \fIcode\fP                      Compiled regular expression
+  \fIadjust\fP                    Adjustment to reference value
+.sp
+The yield of the function is the adjusted reference value, which is constrained
+to lie between 0 and 65535.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_study.3 b/doc/pcre_study.3
new file mode 100644
index 0000000..1200e0a
--- /dev/null
+++ b/doc/pcre_study.3
@@ -0,0 +1,54 @@
+.TH PCRE_STUDY 3 " 24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP);"
+.sp
+.B pcre16_extra *pcre16_study(const pcre16 *\fIcode\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP);"
+.sp
+.B pcre32_extra *pcre32_study(const pcre32 *\fIcode\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function studies a compiled pattern, to see if additional information can
+be extracted that might speed up matching. Its arguments are:
+.sp
+  \fIcode\fP       A compiled regular expression
+  \fIoptions\fP    Options for \fBpcre[16|32]_study()\fP
+  \fIerrptr\fP     Where to put an error message
+.sp
+If the function succeeds, it returns a value that can be passed to
+\fBpcre[16|32]_exec()\fP or \fBpcre[16|32]_dfa_exec()\fP via their \fIextra\fP
+arguments.
+.P
+If the function returns NULL, either it could not find any additional
+information, or there was an error. You can tell the difference by looking at
+the error value. It is NULL in first case.
+.P
+The only option is PCRE_STUDY_JIT_COMPILE. It requests just-in-time compilation
+if possible. If PCRE has been compiled without JIT support, this option is
+ignored. See the
+.\" HREF
+\fBpcrejit\fP
+.\"
+page for further details.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_utf16_to_host_byte_order.3 b/doc/pcre_utf16_to_host_byte_order.3
new file mode 100644
index 0000000..1851b61
--- /dev/null
+++ b/doc/pcre_utf16_to_host_byte_order.3
@@ -0,0 +1,45 @@
+.TH PCRE_UTF16_TO_HOST_BYTE_ORDER 3 "21 January 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *\fIoutput\fP,
+.B "     PCRE_SPTR16 \fIinput\fP, int \fIlength\fP, int *\fIhost_byte_order\fP,"
+.B "     int \fIkeep_boms\fP);"
+.fi
+.
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function, which exists only in the 16-bit library, converts a UTF-16
+string to the correct order for the current host, taking account of any byte
+order marks (BOMs) within the string. Its arguments are:
+.sp
+  \fIoutput\fP           pointer to output buffer, may be the same as \fIinput\fP
+  \fIinput\fP            pointer to input buffer
+  \fIlength\fP           number of 16-bit units in the input, or negative for
+                     a zero-terminated string
+  \fIhost_byte_order\fP  a NULL value or a non-zero value pointed to means
+                     start in host byte order
+  \fIkeep_boms\fP        if non-zero, BOMs are copied to the output string
+.sp
+The result of the function is the number of 16-bit units placed into the output
+buffer, including the zero terminator if the string was zero-terminated.
+.P
+If \fIhost_byte_order\fP is not NULL, it is set to indicate the byte order that
+is current at the end of the string.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_utf32_to_host_byte_order.3 b/doc/pcre_utf32_to_host_byte_order.3
new file mode 100644
index 0000000..a415dcf
--- /dev/null
+++ b/doc/pcre_utf32_to_host_byte_order.3
@@ -0,0 +1,45 @@
+.TH PCRE_UTF32_TO_HOST_BYTE_ORDER 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *\fIoutput\fP,
+.B "     PCRE_SPTR32 \fIinput\fP, int \fIlength\fP, int *\fIhost_byte_order\fP,"
+.B "     int \fIkeep_boms\fP);"
+.fi
+.
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function, which exists only in the 32-bit library, converts a UTF-32
+string to the correct order for the current host, taking account of any byte
+order marks (BOMs) within the string. Its arguments are:
+.sp
+  \fIoutput\fP           pointer to output buffer, may be the same as \fIinput\fP
+  \fIinput\fP            pointer to input buffer
+  \fIlength\fP           number of 32-bit units in the input, or negative for
+                     a zero-terminated string
+  \fIhost_byte_order\fP  a NULL value or a non-zero value pointed to means
+                     start in host byte order
+  \fIkeep_boms\fP        if non-zero, BOMs are copied to the output string
+.sp
+The result of the function is the number of 32-bit units placed into the output
+buffer, including the zero terminator if the string was zero-terminated.
+.P
+If \fIhost_byte_order\fP is not NULL, it is set to indicate the byte order that
+is current at the end of the string.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcre_version.3 b/doc/pcre_version.3
new file mode 100644
index 0000000..0f4973f
--- /dev/null
+++ b/doc/pcre_version.3
@@ -0,0 +1,31 @@
+.TH PCRE_VERSION 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.SM
+.B const char *pcre_version(void);
+.PP
+.B const char *pcre16_version(void);
+.PP
+.B const char *pcre32_version(void);
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function (even in the 16-bit and 32-bit libraries) returns a
+zero-terminated, 8-bit character string that gives the version number of the
+PCRE library and the date of its release.
+.P
+There is a complete description of the PCRE native API in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+page.
diff --git a/doc/pcreapi.3 b/doc/pcreapi.3
new file mode 100644
index 0000000..ab3eaa0
--- /dev/null
+++ b/doc/pcreapi.3
@@ -0,0 +1,2919 @@
+.TH PCREAPI 3 "09 February 2014" "PCRE 8.35"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.sp
+.B #include 
+.
+.
+.SH "PCRE NATIVE API BASIC FUNCTIONS"
+.rs
+.sp
+.nf
+.B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
+.B "     int *\fIerrorcodeptr\fP,"
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP);"
+.sp
+.B void pcre_free_study(pcre_extra *\fIextra\fP);
+.sp
+.B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     const char *\fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);"
+.sp
+.B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     const char *\fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     int *\fIworkspace\fP, int \fIwscount\fP);"
+.fi
+.
+.
+.SH "PCRE NATIVE API STRING EXTRACTION FUNCTIONS"
+.rs
+.sp
+.nf
+.B int pcre_copy_named_substring(const pcre *\fIcode\fP,
+.B "     const char *\fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, const char *\fIstringname\fP,"
+.B "     char *\fIbuffer\fP, int \fIbuffersize\fP);"
+.sp
+.B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,"
+.B "     int \fIbuffersize\fP);"
+.sp
+.B int pcre_get_named_substring(const pcre *\fIcode\fP,
+.B "     const char *\fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, const char *\fIstringname\fP,"
+.B "     const char **\fIstringptr\fP);"
+.sp
+.B int pcre_get_stringnumber(const pcre *\fIcode\fP,
+.B "     const char *\fIname\fP);"
+.sp
+.B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
+.B "     const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);"
+.sp
+.B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP,"
+.B "     const char **\fIstringptr\fP);"
+.sp
+.B int pcre_get_substring_list(const char *\fIsubject\fP,
+.B "     int *\fIovector\fP, int \fIstringcount\fP, const char ***\fIlistptr\fP);"
+.sp
+.B void pcre_free_substring(const char *\fIstringptr\fP);
+.sp
+.B void pcre_free_substring_list(const char **\fIstringptr\fP);
+.fi
+.
+.
+.SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
+.rs
+.sp
+.nf
+.B int pcre_jit_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     const char *\fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     pcre_jit_stack *\fIjstack\fP);"
+.sp
+.B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
+.sp
+.B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
+.sp
+.B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
+.B "     pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);"
+.sp
+.B const unsigned char *pcre_maketables(void);
+.sp
+.B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     int \fIwhat\fP, void *\fIwhere\fP);"
+.sp
+.B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
+.sp
+.B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
+.sp
+.B const char *pcre_version(void);
+.sp
+.B int pcre_pattern_to_host_byte_order(pcre *\fIcode\fP,
+.B "     pcre_extra *\fIextra\fP, const unsigned char *\fItables\fP);"
+.fi
+.
+.
+.SH "PCRE NATIVE API INDIRECTED FUNCTIONS"
+.rs
+.sp
+.nf
+.B void *(*pcre_malloc)(size_t);
+.sp
+.B void (*pcre_free)(void *);
+.sp
+.B void *(*pcre_stack_malloc)(size_t);
+.sp
+.B void (*pcre_stack_free)(void *);
+.sp
+.B int (*pcre_callout)(pcre_callout_block *);
+.sp
+.B int (*pcre_stack_guard)(void);
+.fi
+.
+.
+.SH "PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES"
+.rs
+.sp
+As well as support for 8-bit character strings, PCRE also supports 16-bit
+strings (from release 8.30) and 32-bit strings (from release 8.32), by means of
+two additional libraries. They can be built as well as, or instead of, the
+8-bit library. To avoid too much complication, this document describes the
+8-bit versions of the functions, with only occasional references to the 16-bit
+and 32-bit libraries.
+.P
+The 16-bit and 32-bit functions operate in the same way as their 8-bit
+counterparts; they just use different data types for their arguments and
+results, and their names start with \fBpcre16_\fP or \fBpcre32_\fP instead of
+\fBpcre_\fP. For every option that has UTF8 in its name (for example,
+PCRE_UTF8), there are corresponding 16-bit and 32-bit names with UTF8 replaced
+by UTF16 or UTF32, respectively. This facility is in fact just cosmetic; the
+16-bit and 32-bit option names define the same bit values.
+.P
+References to bytes and UTF-8 in this document should be read as references to
+16-bit data units and UTF-16 when using the 16-bit library, or 32-bit data
+units and UTF-32 when using the 32-bit library, unless specified otherwise.
+More details of the specific differences for the 16-bit and 32-bit libraries
+are given in the
+.\" HREF
+\fBpcre16\fP
+.\"
+and
+.\" HREF
+\fBpcre32\fP
+.\"
+pages.
+.
+.
+.SH "PCRE API OVERVIEW"
+.rs
+.sp
+PCRE has its own native API, which is described in this document. There are
+also some wrapper functions (for the 8-bit library only) that correspond to the
+POSIX regular expression API, but they do not give access to all the
+functionality. They are described in the
+.\" HREF
+\fBpcreposix\fP
+.\"
+documentation. Both of these APIs define a set of C function calls. A C++
+wrapper (again for the 8-bit library only) is also distributed with PCRE. It is
+documented in the
+.\" HREF
+\fBpcrecpp\fP
+.\"
+page.
+.P
+The native API C function prototypes are defined in the header file
+\fBpcre.h\fP, and on Unix-like systems the (8-bit) library itself is called
+\fBlibpcre\fP. It can normally be accessed by adding \fB-lpcre\fP to the
+command for linking an application that uses PCRE. The header file defines the
+macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release numbers
+for the library. Applications can use these to include support for different
+releases of PCRE.
+.P
+In a Windows environment, if you want to statically link an application program
+against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
+including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
+\fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
+\fB__declspec(dllimport)\fP, with unwanted results.
+.P
+The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
+and \fBpcre_exec()\fP are used for compiling and matching regular expressions
+in a Perl-compatible manner. A sample program that demonstrates the simplest
+way of using them is provided in the file called \fIpcredemo.c\fP in the PCRE
+source distribution. A listing of this program is given in the
+.\" HREF
+\fBpcredemo\fP
+.\"
+documentation, and the
+.\" HREF
+\fBpcresample\fP
+.\"
+documentation describes how to compile and run it.
+.P
+Just-in-time compiler support is an optional feature of PCRE that can be built
+in appropriate hardware environments. It greatly speeds up the matching
+performance of many patterns. Simple programs can easily request that it be
+used if available, by setting an option that is ignored when it is not
+relevant. More complicated programs might need to make use of the functions
+\fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
+\fBpcre_assign_jit_stack()\fP in order to control the JIT code's memory usage.
+.P
+From release 8.32 there is also a direct interface for JIT execution, which
+gives improved performance. The JIT-specific functions are discussed in the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation.
+.P
+A second matching function, \fBpcre_dfa_exec()\fP, which is not
+Perl-compatible, is also provided. This uses a different algorithm for the
+matching. The alternative algorithm finds all possible matches (at a given
+point in the subject), and scans the subject just once (unless there are
+lookbehind assertions). However, this algorithm does not return captured
+substrings. A description of the two matching algorithms and their advantages
+and disadvantages is given in the
+.\" HREF
+\fBpcrematching\fP
+.\"
+documentation.
+.P
+In addition to the main compiling and matching functions, there are convenience
+functions for extracting captured substrings from a subject string that is
+matched by \fBpcre_exec()\fP. They are:
+.sp
+  \fBpcre_copy_substring()\fP
+  \fBpcre_copy_named_substring()\fP
+  \fBpcre_get_substring()\fP
+  \fBpcre_get_named_substring()\fP
+  \fBpcre_get_substring_list()\fP
+  \fBpcre_get_stringnumber()\fP
+  \fBpcre_get_stringtable_entries()\fP
+.sp
+\fBpcre_free_substring()\fP and \fBpcre_free_substring_list()\fP are also
+provided, to free the memory used for extracted strings.
+.P
+The function \fBpcre_maketables()\fP is used to build a set of character tables
+in the current locale for passing to \fBpcre_compile()\fP, \fBpcre_exec()\fP,
+or \fBpcre_dfa_exec()\fP. This is an optional facility that is provided for
+specialist use. Most commonly, no special tables are passed, in which case
+internal tables that are generated when PCRE is built are used.
+.P
+The function \fBpcre_fullinfo()\fP is used to find out information about a
+compiled pattern. The function \fBpcre_version()\fP returns a pointer to a
+string containing the version of PCRE and its date of release.
+.P
+The function \fBpcre_refcount()\fP maintains a reference count in a data block
+containing a compiled pattern. This is provided for the benefit of
+object-oriented applications.
+.P
+The global variables \fBpcre_malloc\fP and \fBpcre_free\fP initially contain
+the entry points of the standard \fBmalloc()\fP and \fBfree()\fP functions,
+respectively. PCRE calls the memory management functions via these variables,
+so a calling program can replace them if it wishes to intercept the calls. This
+should be done before calling any PCRE functions.
+.P
+The global variables \fBpcre_stack_malloc\fP and \fBpcre_stack_free\fP are also
+indirections to memory management functions. These special functions are used
+only when PCRE is compiled to use the heap for remembering data, instead of
+recursive function calls, when running the \fBpcre_exec()\fP function. See the
+.\" HREF
+\fBpcrebuild\fP
+.\"
+documentation for details of how to do this. It is a non-standard way of
+building PCRE, for use in environments that have limited stacks. Because of the
+greater use of memory management, it runs more slowly. Separate functions are
+provided so that special-purpose external code can be used for this case. When
+used, these functions are always called in a stack-like manner (last obtained,
+first freed), and always for memory blocks of the same size. There is a
+discussion about PCRE's stack usage in the
+.\" HREF
+\fBpcrestack\fP
+.\"
+documentation.
+.P
+The global variable \fBpcre_callout\fP initially contains NULL. It can be set
+by the caller to a "callout" function, which PCRE will then call at specified
+points during a matching operation. Details are given in the
+.\" HREF
+\fBpcrecallout\fP
+.\"
+documentation.
+.P
+The global variable \fBpcre_stack_guard\fP initially contains NULL. It can be
+set by the caller to a function that is called by PCRE whenever it starts
+to compile a parenthesized part of a pattern. When parentheses are nested, PCRE
+uses recursive function calls, which use up the system stack. This function is
+provided so that applications with restricted stacks can force a compilation
+error if the stack runs out. The function should return zero if all is well, or
+non-zero to force an error.
+.
+.
+.\" HTML 
+.SH NEWLINES
+.rs
+.sp
+PCRE supports five different conventions for indicating line breaks in
+strings: a single CR (carriage return) character, a single LF (linefeed)
+character, the two-character sequence CRLF, any of the three preceding, or any
+Unicode newline sequence. The Unicode newline sequences are the three just
+mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed,
+U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
+(paragraph separator, U+2029).
+.P
+Each of the first three conventions is used by at least one operating system as
+its standard newline sequence. When PCRE is built, a default can be specified.
+The default default is LF, which is the Unix standard. When PCRE is run, the
+default can be overridden, either when a pattern is compiled, or when it is
+matched.
+.P
+At compile time, the newline convention can be specified by the \fIoptions\fP
+argument of \fBpcre_compile()\fP, or it can be specified by special text at the
+start of the pattern itself; this overrides any other settings. See the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+page for details of the special character sequences.
+.P
+In the PCRE documentation the word "newline" is used to mean "the character or
+pair of characters that indicate a line break". The choice of newline
+convention affects the handling of the dot, circumflex, and dollar
+metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
+recognized line ending sequence, the match position advancement for a
+non-anchored pattern. There is more detail about this in the
+.\" HTML 
+.\" 
+section on \fBpcre_exec()\fP options
+.\"
+below.
+.P
+The choice of newline convention does not affect the interpretation of
+the \en or \er escape sequences, nor does it affect what \eR matches, which is
+controlled in a similar way, but by separate options.
+.
+.
+.SH MULTITHREADING
+.rs
+.sp
+The PCRE functions can be used in multi-threading applications, with the
+proviso that the memory management functions pointed to by \fBpcre_malloc\fP,
+\fBpcre_free\fP, \fBpcre_stack_malloc\fP, and \fBpcre_stack_free\fP, and the
+callout and stack-checking functions pointed to by \fBpcre_callout\fP and
+\fBpcre_stack_guard\fP, are shared by all threads.
+.P
+The compiled form of a regular expression is not altered during matching, so
+the same compiled pattern can safely be used by several threads at once.
+.P
+If the just-in-time optimization feature is being used, it needs separate
+memory stack areas for each thread. See the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation for more details.
+.
+.
+.SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
+.rs
+.sp
+The compiled form of a regular expression can be saved and re-used at a later
+time, possibly by a different program, and even on a host other than the one on
+which it was compiled. Details are given in the
+.\" HREF
+\fBpcreprecompile\fP
+.\"
+documentation, which includes a description of the
+\fBpcre_pattern_to_host_byte_order()\fP function. However, compiling a regular
+expression with one version of PCRE for use with a different version is not
+guaranteed to work and may cause crashes.
+.
+.
+.SH "CHECKING BUILD-TIME OPTIONS"
+.rs
+.sp
+.B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
+.PP
+The function \fBpcre_config()\fP makes it possible for a PCRE client to
+discover which optional features have been compiled into the PCRE library. The
+.\" HREF
+\fBpcrebuild\fP
+.\"
+documentation has more details about these optional features.
+.P
+The first argument for \fBpcre_config()\fP is an integer, specifying which
+information is required; the second argument is a pointer to a variable into
+which the information is placed. The returned value is zero on success, or the
+negative error code PCRE_ERROR_BADOPTION if the value in the first argument is
+not recognized. The following information is available:
+.sp
+  PCRE_CONFIG_UTF8
+.sp
+The output is an integer that is set to one if UTF-8 support is available;
+otherwise it is set to zero. This value should normally be given to the 8-bit
+version of this function, \fBpcre_config()\fP. If it is given to the 16-bit
+or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION.
+.sp
+  PCRE_CONFIG_UTF16
+.sp
+The output is an integer that is set to one if UTF-16 support is available;
+otherwise it is set to zero. This value should normally be given to the 16-bit
+version of this function, \fBpcre16_config()\fP. If it is given to the 8-bit
+or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION.
+.sp
+  PCRE_CONFIG_UTF32
+.sp
+The output is an integer that is set to one if UTF-32 support is available;
+otherwise it is set to zero. This value should normally be given to the 32-bit
+version of this function, \fBpcre32_config()\fP. If it is given to the 8-bit
+or 16-bit version of this function, the result is PCRE_ERROR_BADOPTION.
+.sp
+  PCRE_CONFIG_UNICODE_PROPERTIES
+.sp
+The output is an integer that is set to one if support for Unicode character
+properties is available; otherwise it is set to zero.
+.sp
+  PCRE_CONFIG_JIT
+.sp
+The output is an integer that is set to one if support for just-in-time
+compiling is available; otherwise it is set to zero.
+.sp
+  PCRE_CONFIG_JITTARGET
+.sp
+The output is a pointer to a zero-terminated "const char *" string. If JIT
+support is available, the string contains the name of the architecture for
+which the JIT compiler is configured, for example "x86 32bit (little endian +
+unaligned)". If JIT support is not available, the result is NULL.
+.sp
+  PCRE_CONFIG_NEWLINE
+.sp
+The output is an integer whose value specifies the default character sequence
+that is recognized as meaning "newline". The values that are supported in
+ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for
+ANYCRLF, and -1 for ANY. In EBCDIC environments, CR, ANYCRLF, and ANY yield the
+same values. However, the value for LF is normally 21, though some EBCDIC
+environments use 37. The corresponding values for CRLF are 3349 and 3365. The
+default should normally correspond to the standard sequence for your operating
+system.
+.sp
+  PCRE_CONFIG_BSR
+.sp
+The output is an integer whose value indicates what character sequences the \eR
+escape sequence matches by default. A value of 0 means that \eR matches any
+Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
+or CRLF. The default can be overridden when a pattern is compiled or matched.
+.sp
+  PCRE_CONFIG_LINK_SIZE
+.sp
+The output is an integer that contains the number of bytes used for internal
+linkage in compiled regular expressions. For the 8-bit library, the value can
+be 2, 3, or 4. For the 16-bit library, the value is either 2 or 4 and is still
+a number of bytes. For the 32-bit library, the value is either 2 or 4 and is
+still a number of bytes. The default value of 2 is sufficient for all but the
+most massive patterns, since it allows the compiled pattern to be up to 64K in
+size. Larger values allow larger regular expressions to be compiled, at the
+expense of slower matching.
+.sp
+  PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
+.sp
+The output is an integer that contains the threshold above which the POSIX
+interface uses \fBmalloc()\fP for output vectors. Further details are given in
+the
+.\" HREF
+\fBpcreposix\fP
+.\"
+documentation.
+.sp
+  PCRE_CONFIG_PARENS_LIMIT
+.sp
+The output is a long integer that gives the maximum depth of nesting of
+parentheses (of any kind) in a pattern. This limit is imposed to cap the amount
+of system stack used when a pattern is compiled. It is specified when PCRE is
+built; the default is 250. This limit does not take into account the stack that
+may already be used by the calling application. For finer control over
+compilation stack usage, you can set a pointer to an external checking function
+in \fBpcre_stack_guard\fP.
+.sp
+  PCRE_CONFIG_MATCH_LIMIT
+.sp
+The output is a long integer that gives the default limit for the number of
+internal matching function calls in a \fBpcre_exec()\fP execution. Further
+details are given with \fBpcre_exec()\fP below.
+.sp
+  PCRE_CONFIG_MATCH_LIMIT_RECURSION
+.sp
+The output is a long integer that gives the default limit for the depth of
+recursion when calling the internal matching function in a \fBpcre_exec()\fP
+execution. Further details are given with \fBpcre_exec()\fP below.
+.sp
+  PCRE_CONFIG_STACKRECURSE
+.sp
+The output is an integer that is set to one if internal recursion when running
+\fBpcre_exec()\fP is implemented by recursive function calls that use the stack
+to remember their state. This is the usual way that PCRE is compiled. The
+output is zero if PCRE was compiled to use blocks of data on the heap instead
+of recursive function calls. In this case, \fBpcre_stack_malloc\fP and
+\fBpcre_stack_free\fP are called to manage memory blocks on the heap, thus
+avoiding the use of the stack.
+.
+.
+.SH "COMPILING A PATTERN"
+.rs
+.sp
+.nf
+.B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.sp
+.B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
+.B "     int *\fIerrorcodeptr\fP,"
+.B "     const char **\fIerrptr\fP, int *\fIerroffset\fP,"
+.B "     const unsigned char *\fItableptr\fP);"
+.fi
+.P
+Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
+called to compile a pattern into an internal form. The only difference between
+the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
+\fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
+too much repetition, we refer just to \fBpcre_compile()\fP below, but the
+information applies equally to \fBpcre_compile2()\fP.
+.P
+The pattern is a C string terminated by a binary zero, and is passed in the
+\fIpattern\fP argument. A pointer to a single block of memory that is obtained
+via \fBpcre_malloc\fP is returned. This contains the compiled code and related
+data. The \fBpcre\fP type is defined for the returned block; this is a typedef
+for a structure whose contents are not externally defined. It is up to the
+caller to free the memory (via \fBpcre_free\fP) when it is no longer required.
+.P
+Although the compiled code of a PCRE regex is relocatable, that is, it does not
+depend on memory location, the complete \fBpcre\fP data block is not
+fully relocatable, because it may contain a copy of the \fItableptr\fP
+argument, which is an address (see below).
+.P
+The \fIoptions\fP argument contains various bit settings that affect the
+compilation. It should be zero if no options are required. The available
+options are described below. Some of them (in particular, those that are
+compatible with Perl, but some others as well) can also be set and unset from
+within the pattern (see the detailed description in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+documentation). For those options that can be different in different parts of
+the pattern, the contents of the \fIoptions\fP argument specifies their
+settings at the start of compilation and execution. The PCRE_ANCHORED,
+PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
+PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at
+compile time.
+.P
+If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
+Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
+NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
+error message. This is a static string that is part of the library. You must
+not try to free it. Normally, the offset from the start of the pattern to the
+data unit that was being processed when the error was discovered is placed in
+the variable pointed to by \fIerroffset\fP, which must not be NULL (if it is,
+an immediate error is given). However, for an invalid UTF-8 or UTF-16 string,
+the offset is that of the first data unit of the failing character.
+.P
+Some errors are not detected until the whole pattern has been scanned; in these
+cases, the offset passed back is the length of the pattern. Note that the
+offset is in data units, not characters, even in a UTF mode. It may sometimes
+point into the middle of a UTF-8 or UTF-16 character.
+.P
+If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
+\fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
+returned via this argument in the event of an error. This is in addition to the
+textual error message. Error codes and messages are listed below.
+.P
+If the final argument, \fItableptr\fP, is NULL, PCRE uses a default set of
+character tables that are built when PCRE is compiled, using the default C
+locale. Otherwise, \fItableptr\fP must be an address that is the result of a
+call to \fBpcre_maketables()\fP. This value is stored with the compiled
+pattern, and used again by \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP when the
+pattern is matched. For more discussion, see the section on locale support
+below.
+.P
+This code fragment shows a typical straightforward call to \fBpcre_compile()\fP:
+.sp
+  pcre *re;
+  const char *error;
+  int erroffset;
+  re = pcre_compile(
+    "^A.*Z",          /* the pattern */
+    0,                /* default options */
+    &error,           /* for error message */
+    &erroffset,       /* for error offset */
+    NULL);            /* use default character tables */
+.sp
+The following names for option bits are defined in the \fBpcre.h\fP header
+file:
+.sp
+  PCRE_ANCHORED
+.sp
+If this bit is set, the pattern is forced to be "anchored", that is, it is
+constrained to match only at the first matching point in the string that is
+being searched (the "subject string"). This effect can also be achieved by
+appropriate constructs in the pattern itself, which is the only way to do it in
+Perl.
+.sp
+  PCRE_AUTO_CALLOUT
+.sp
+If this bit is set, \fBpcre_compile()\fP automatically inserts callout items,
+all with number 255, before each pattern item. For discussion of the callout
+facility, see the
+.\" HREF
+\fBpcrecallout\fP
+.\"
+documentation.
+.sp
+  PCRE_BSR_ANYCRLF
+  PCRE_BSR_UNICODE
+.sp
+These options (which are mutually exclusive) control what the \eR escape
+sequence matches. The choice is either to match only CR, LF, or CRLF, or to
+match any Unicode newline sequence. The default is specified when PCRE is
+built. It can be overridden from within the pattern, or by setting an option
+when a compiled pattern is matched.
+.sp
+  PCRE_CASELESS
+.sp
+If this bit is set, letters in the pattern match both upper and lower case
+letters. It is equivalent to Perl's /i option, and it can be changed within a
+pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
+concept of case for characters whose values are less than 128, so caseless
+matching is always possible. For characters with higher values, the concept of
+case is supported if PCRE is compiled with Unicode property support, but not
+otherwise. If you want to use caseless matching for characters 128 and above,
+you must ensure that PCRE is compiled with Unicode property support as well as
+with UTF-8 support.
+.sp
+  PCRE_DOLLAR_ENDONLY
+.sp
+If this bit is set, a dollar metacharacter in the pattern matches only at the
+end of the subject string. Without this option, a dollar also matches
+immediately before a newline at the end of the string (but not before any other
+newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
+There is no equivalent to this option in Perl, and no way to set it within a
+pattern.
+.sp
+  PCRE_DOTALL
+.sp
+If this bit is set, a dot metacharacter in the pattern matches a character of
+any value, including one that indicates a newline. However, it only ever
+matches one character, even if newlines are coded as CRLF. Without this option,
+a dot does not match when the current position is at a newline. This option is
+equivalent to Perl's /s option, and it can be changed within a pattern by a
+(?s) option setting. A negative class such as [^a] always matches newline
+characters, independent of the setting of this option.
+.sp
+  PCRE_DUPNAMES
+.sp
+If this bit is set, names used to identify capturing subpatterns need not be
+unique. This can be helpful for certain types of pattern when it is known that
+only one instance of the named subpattern can ever be matched. There are more
+details of named subpatterns below; see also the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+documentation.
+.sp
+  PCRE_EXTENDED
+.sp
+If this bit is set, most white space characters in the pattern are totally
+ignored except when escaped or inside a character class. However, white space
+is not allowed within sequences such as (?> that introduce various
+parenthesized subpatterns, nor within a numerical quantifier such as {1,3}.
+However, ignorable white space is permitted between an item and a following
+quantifier and between a quantifier and a following + that indicates
+possessiveness.
+.P
+White space did not used to include the VT character (code 11), because Perl
+did not treat this character as white space. However, Perl changed at release
+5.18, so PCRE followed at release 8.34, and VT is now treated as white space.
+.P
+PCRE_EXTENDED also causes characters between an unescaped # outside a character
+class and the next newline, inclusive, to be ignored. PCRE_EXTENDED is
+equivalent to Perl's /x option, and it can be changed within a pattern by a
+(?x) option setting.
+.P
+Which characters are interpreted as newlines is controlled by the options
+passed to \fBpcre_compile()\fP or by a special sequence at the start of the
+pattern, as described in the section entitled
+.\" HTML 
+.\" 
+"Newline conventions"
+.\"
+in the \fBpcrepattern\fP documentation. Note that the end of this type of
+comment is a literal newline sequence in the pattern; escape sequences that
+happen to represent a newline do not count.
+.P
+This option makes it possible to include comments inside complicated patterns.
+Note, however, that this applies only to data characters. White space characters
+may never appear within special character sequences in a pattern, for example
+within the sequence (?( that introduces a conditional subpattern.
+.sp
+  PCRE_EXTRA
+.sp
+This option was invented in order to turn on additional functionality of PCRE
+that is incompatible with Perl, but it is currently of very little use. When
+set, any backslash in a pattern that is followed by a letter that has no
+special meaning causes an error, thus reserving these combinations for future
+expansion. By default, as in Perl, a backslash followed by a letter with no
+special meaning is treated as a literal. (Perl can, however, be persuaded to
+give an error for this, by running it with the -w option.) There are at present
+no other features controlled by this option. It can also be set by a (?X)
+option setting within a pattern.
+.sp
+  PCRE_FIRSTLINE
+.sp
+If this option is set, an unanchored pattern is required to match before or at
+the first newline in the subject string, though the matched text may continue
+over the newline.
+.sp
+  PCRE_JAVASCRIPT_COMPAT
+.sp
+If this option is set, PCRE's behaviour is changed in some ways so that it is
+compatible with JavaScript rather than Perl. The changes are as follows:
+.P
+(1) A lone closing square bracket in a pattern causes a compile-time error,
+because this is illegal in JavaScript (by default it is treated as a data
+character). Thus, the pattern AB]CD becomes illegal when this option is set.
+.P
+(2) At run time, a back reference to an unset subpattern group matches an empty
+string (by default this causes the current matching alternative to fail). A
+pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
+an "a" in the subject), whereas it fails by default, for Perl compatibility.
+.P
+(3) \eU matches an upper case "U" character; by default \eU causes a compile
+time error (Perl uses \eU to upper case subsequent characters).
+.P
+(4) \eu matches a lower case "u" character unless it is followed by four
+hexadecimal digits, in which case the hexadecimal number defines the code point
+to match. By default, \eu causes a compile time error (Perl uses it to upper
+case the following character).
+.P
+(5) \ex matches a lower case "x" character unless it is followed by two
+hexadecimal digits, in which case the hexadecimal number defines the code point
+to match. By default, as in Perl, a hexadecimal number is always expected after
+\ex, but it may have zero, one, or two digits (so, for example, \exz matches a
+binary zero character followed by z).
+.sp
+  PCRE_MULTILINE
+.sp
+By default, for the purposes of matching "start of line" and "end of line",
+PCRE treats the subject string as consisting of a single line of characters,
+even if it actually contains newlines. The "start of line" metacharacter (^)
+matches only at the start of the string, and the "end of line" metacharacter
+($) matches only at the end of the string, or before a terminating newline
+(except when PCRE_DOLLAR_ENDONLY is set). Note, however, that unless
+PCRE_DOTALL is set, the "any character" metacharacter (.) does not match at a
+newline. This behaviour (for ^, $, and dot) is the same as Perl.
+.P
+When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs
+match immediately following or immediately before internal newlines in the
+subject string, respectively, as well as at the very start and end. This is
+equivalent to Perl's /m option, and it can be changed within a pattern by a
+(?m) option setting. If there are no newlines in a subject string, or no
+occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
+.sp
+  PCRE_NEVER_UTF
+.sp
+This option locks out interpretation of the pattern as UTF-8 (or UTF-16 or
+UTF-32 in the 16-bit and 32-bit libraries). In particular, it prevents the
+creator of the pattern from switching to UTF interpretation by starting the
+pattern with (*UTF). This may be useful in applications that process patterns
+from external sources. The combination of PCRE_UTF8 and PCRE_NEVER_UTF also
+causes an error.
+.sp
+  PCRE_NEWLINE_CR
+  PCRE_NEWLINE_LF
+  PCRE_NEWLINE_CRLF
+  PCRE_NEWLINE_ANYCRLF
+  PCRE_NEWLINE_ANY
+.sp
+These options override the default newline definition that was chosen when PCRE
+was built. Setting the first or the second specifies that a newline is
+indicated by a single character (CR or LF, respectively). Setting
+PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
+CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
+preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
+that any Unicode newline sequence should be recognized.
+.P
+In an ASCII/Unicode environment, the Unicode newline sequences are the three
+just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form
+feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
+(paragraph separator, U+2029). For the 8-bit library, the last two are
+recognized only in UTF-8 mode.
+.P
+When PCRE is compiled to run in an EBCDIC (mainframe) environment, the code for
+CR is 0x0d, the same as ASCII. However, the character code for LF is normally
+0x15, though in some EBCDIC environments 0x25 is used. Whichever of these is
+not LF is made to correspond to Unicode's NEL character. EBCDIC codes are all
+less than 256. For more details, see the
+.\" HREF
+\fBpcrebuild\fP
+.\"
+documentation.
+.P
+The newline setting in the options word uses three bits that are treated
+as a number, giving eight possibilities. Currently only six are used (default
+plus the five values above). This means that if you set more than one newline
+option, the combination may or may not be sensible. For example,
+PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
+other combinations may yield unused numbers and cause an error.
+.P
+The only time that a line break in a pattern is specially recognized when
+compiling is when PCRE_EXTENDED is set. CR and LF are white space characters,
+and so are ignored in this mode. Also, an unescaped # outside a character class
+indicates a comment that lasts until after the next line break sequence. In
+other circumstances, line break sequences in patterns are treated as literal
+data.
+.P
+The newline option that is set at compile time becomes the default that is used
+for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
+.sp
+  PCRE_NO_AUTO_CAPTURE
+.sp
+If this option is set, it disables the use of numbered capturing parentheses in
+the pattern. Any opening parenthesis that is not followed by ? behaves as if it
+were followed by ?: but named parentheses can still be used for capturing (and
+they acquire numbers in the usual way). There is no equivalent of this option
+in Perl.
+.sp
+  PCRE_NO_AUTO_POSSESS
+.sp
+If this option is set, it disables "auto-possessification". This is an
+optimization that, for example, turns a+b into a++b in order to avoid
+backtracks into a+ that can never be successful. However, if callouts are in
+use, auto-possessification means that some of them are never taken. You can set
+this option if you want the matching functions to do a full unoptimized search
+and run all the callouts, but it is mainly provided for testing purposes.
+.sp
+  PCRE_NO_START_OPTIMIZE
+.sp
+This is an option that acts at matching time; that is, it is really an option
+for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
+it is remembered with the compiled pattern and assumed at matching time. This
+is necessary if you want to use JIT execution, because the JIT compiler needs
+to know whether or not this option is set. For details see the discussion of
+PCRE_NO_START_OPTIMIZE
+.\" HTML 
+.\" 
+below.
+.\"
+.sp
+  PCRE_UCP
+.sp
+This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
+\ew, and some of the POSIX character classes. By default, only ASCII characters
+are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
+classify characters. More details are given in the section on
+.\" HTML 
+.\" 
+generic character types
+.\"
+in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+page. If you set PCRE_UCP, matching one of the items it affects takes much
+longer. The option is available only if PCRE has been compiled with Unicode
+property support.
+.sp
+  PCRE_UNGREEDY
+.sp
+This option inverts the "greediness" of the quantifiers so that they are not
+greedy by default, but become greedy if followed by "?". It is not compatible
+with Perl. It can also be set by a (?U) option setting within the pattern.
+.sp
+  PCRE_UTF8
+.sp
+This option causes PCRE to regard both the pattern and the subject as strings
+of UTF-8 characters instead of single-byte strings. However, it is available
+only when PCRE is built to include UTF support. If not, the use of this option
+provokes an error. Details of how this option changes the behaviour of PCRE are
+given in the
+.\" HREF
+\fBpcreunicode\fP
+.\"
+page.
+.sp
+  PCRE_NO_UTF8_CHECK
+.sp
+When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
+automatically checked. There is a discussion about the
+.\" HTML 
+.\" 
+validity of UTF-8 strings
+.\"
+in the
+.\" HREF
+\fBpcreunicode\fP
+.\"
+page. If an invalid UTF-8 sequence is found, \fBpcre_compile()\fP returns an
+error. If you already know that your pattern is valid, and you want to skip
+this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK option.
+When it is set, the effect of passing an invalid UTF-8 string as a pattern is
+undefined. It may cause your program to crash or loop. Note that this option
+can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress
+the validity checking of subject strings only. If the same string is being
+matched many times, the option can be safely set for the second and subsequent
+matchings to improve performance.
+.
+.
+.SH "COMPILATION ERROR CODES"
+.rs
+.sp
+The following table lists the error codes than may be returned by
+\fBpcre_compile2()\fP, along with the error messages that may be returned by
+both compiling functions. Note that error messages are always 8-bit ASCII
+strings, even in 16-bit or 32-bit mode. As PCRE has developed, some error codes
+have fallen out of use. To avoid confusion, they have not been re-used.
+.sp
+   0  no error
+   1  \e at end of pattern
+   2  \ec at end of pattern
+   3  unrecognized character follows \e
+   4  numbers out of order in {} quantifier
+   5  number too big in {} quantifier
+   6  missing terminating ] for character class
+   7  invalid escape sequence in character class
+   8  range out of order in character class
+   9  nothing to repeat
+  10  [this code is not in use]
+  11  internal error: unexpected repeat
+  12  unrecognized character after (? or (?-
+  13  POSIX named classes are supported only within a class
+  14  missing )
+  15  reference to non-existent subpattern
+  16  erroffset passed as NULL
+  17  unknown option bit(s) set
+  18  missing ) after comment
+  19  [this code is not in use]
+  20  regular expression is too large
+  21  failed to get memory
+  22  unmatched parentheses
+  23  internal error: code overflow
+  24  unrecognized character after (?<
+  25  lookbehind assertion is not fixed length
+  26  malformed number or name after (?(
+  27  conditional group contains more than two branches
+  28  assertion expected after (?(
+  29  (?R or (?[+-]digits must be followed by )
+  30  unknown POSIX class name
+  31  POSIX collating elements are not supported
+  32  this version of PCRE is compiled without UTF support
+  33  [this code is not in use]
+  34  character value in \ex{} or \eo{} is too large
+  35  invalid condition (?(0)
+  36  \eC not allowed in lookbehind assertion
+  37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
+  38  number after (?C is > 255
+  39  closing ) for (?C expected
+  40  recursive call could loop indefinitely
+  41  unrecognized character after (?P
+  42  syntax error in subpattern name (missing terminator)
+  43  two named subpatterns have the same name
+  44  invalid UTF-8 string (specifically UTF-8)
+  45  support for \eP, \ep, and \eX has not been compiled
+  46  malformed \eP or \ep sequence
+  47  unknown property name after \eP or \ep
+  48  subpattern name is too long (maximum 32 characters)
+  49  too many named subpatterns (maximum 10000)
+  50  [this code is not in use]
+  51  octal value is greater than \e377 in 8-bit non-UTF-8 mode
+  52  internal error: overran compiling workspace
+  53  internal error: previously-checked referenced subpattern
+        not found
+  54  DEFINE group contains more than one branch
+  55  repeating a DEFINE group is not allowed
+  56  inconsistent NEWLINE options
+  57  \eg is not followed by a braced, angle-bracketed, or quoted
+        name/number or by a plain number
+  58  a numbered reference must not be zero
+  59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
+  60  (*VERB) not recognized or malformed
+  61  number is too big
+  62  subpattern name expected
+  63  digit expected after (?+
+  64  ] is an invalid data character in JavaScript compatibility mode
+  65  different names for subpatterns of the same number are
+        not allowed
+  66  (*MARK) must have an argument
+  67  this version of PCRE is not compiled with Unicode property
+        support
+  68  \ec must be followed by an ASCII character
+  69  \ek is not followed by a braced, angle-bracketed, or quoted name
+  70  internal error: unknown opcode in find_fixedlength()
+  71  \eN is not supported in a class
+  72  too many forward references
+  73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
+  74  invalid UTF-16 string (specifically UTF-16)
+  75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
+  76  character value in \eu.... sequence is too large
+  77  invalid UTF-32 string (specifically UTF-32)
+  78  setting UTF is disabled by the application
+  79  non-hex character in \ex{} (closing brace missing?)
+  80  non-octal character in \eo{} (closing brace missing?)
+  81  missing opening brace after \eo
+  82  parentheses are too deeply nested
+  83  invalid range in character class
+  84  group name must start with a non-digit
+  85  parentheses are too deeply nested (stack check)
+.sp
+The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
+be used if the limits were changed when PCRE was built.
+.
+.
+.\" HTML 
+.SH "STUDYING A PATTERN"
+.rs
+.sp
+.nf
+.B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP,
+.B "     const char **\fIerrptr\fP);"
+.fi
+.PP
+If a compiled pattern is going to be used several times, it is worth spending
+more time analyzing it in order to speed up the time taken for matching. The
+function \fBpcre_study()\fP takes a pointer to a compiled pattern as its first
+argument. If studying the pattern produces additional information that will
+help speed up matching, \fBpcre_study()\fP returns a pointer to a
+\fBpcre_extra\fP block, in which the \fIstudy_data\fP field points to the
+results of the study.
+.P
+The returned value from \fBpcre_study()\fP can be passed directly to
+\fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. However, a \fBpcre_extra\fP block
+also contains other fields that can be set by the caller before the block is
+passed; these are described
+.\" HTML 
+.\" 
+below
+.\"
+in the section on matching a pattern.
+.P
+If studying the pattern does not produce any useful information,
+\fBpcre_study()\fP returns NULL by default. In that circumstance, if the
+calling program wants to pass any of the other fields to \fBpcre_exec()\fP or
+\fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block. However,
+if \fBpcre_study()\fP is called with the PCRE_STUDY_EXTRA_NEEDED option, it
+returns a \fBpcre_extra\fP block even if studying did not find any additional
+information. It may still return NULL, however, if an error occurs in
+\fBpcre_study()\fP.
+.P
+The second argument of \fBpcre_study()\fP contains option bits. There are three
+further options in addition to PCRE_STUDY_EXTRA_NEEDED:
+.sp
+  PCRE_STUDY_JIT_COMPILE
+  PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+  PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+.sp
+If any of these are set, and the just-in-time compiler is available, the
+pattern is further compiled into machine code that executes much faster than
+the \fBpcre_exec()\fP interpretive matching function. If the just-in-time
+compiler is not available, these options are ignored. All undefined bits in the
+\fIoptions\fP argument must be zero.
+.P
+JIT compilation is a heavyweight optimization. It can take some time for
+patterns to be analyzed, and for one-off matches and simple patterns the
+benefit of faster execution might be offset by a much slower study time.
+Not all patterns can be optimized by the JIT compiler. For those that cannot be
+handled, matching automatically falls back to the \fBpcre_exec()\fP
+interpreter. For more details, see the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation.
+.P
+The third argument for \fBpcre_study()\fP is a pointer for an error message. If
+studying succeeds (even if no data is returned), the variable it points to is
+set to NULL. Otherwise it is set to point to a textual error message. This is a
+static string that is part of the library. You must not try to free it. You
+should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
+sure that it has run successfully.
+.P
+When you are finished with a pattern, you can free the memory used for the
+study data by calling \fBpcre_free_study()\fP. This function was added to the
+API for release 8.20. For earlier versions, the memory could be freed with
+\fBpcre_free()\fP, just like the pattern itself. This will still work in cases
+where JIT optimization is not used, but it is advisable to change to the new
+function when convenient.
+.P
+This is a typical way in which \fBpcre_study\fP() is used (except that in a
+real application there should be tests for errors):
+.sp
+  int rc;
+  pcre *re;
+  pcre_extra *sd;
+  re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
+  sd = pcre_study(
+    re,             /* result of pcre_compile() */
+    0,              /* no options */
+    &error);        /* set to NULL or points to a message */
+  rc = pcre_exec(   /* see below for details of pcre_exec() options */
+    re, sd, "subject", 7, 0, 0, ovector, 30);
+  ...
+  pcre_free_study(sd);
+  pcre_free(re);
+.sp
+Studying a pattern does two things: first, a lower bound for the length of
+subject string that is needed to match the pattern is computed. This does not
+mean that there are any strings of that length that match, but it does
+guarantee that no shorter strings match. The value is used to avoid wasting
+time by trying to match strings that are shorter than the lower bound. You can
+find out the value in a calling program via the \fBpcre_fullinfo()\fP function.
+.P
+Studying a pattern is also useful for non-anchored patterns that do not have a
+single fixed starting character. A bitmap of possible starting bytes is
+created. This speeds up finding a position in the subject at which to start
+matching. (In 16-bit mode, the bitmap is used for 16-bit values less than 256.
+In 32-bit mode, the bitmap is used for 32-bit values less than 256.)
+.P
+These two optimizations apply to both \fBpcre_exec()\fP and
+\fBpcre_dfa_exec()\fP, and the information is also used by the JIT compiler.
+The optimizations can be disabled by setting the PCRE_NO_START_OPTIMIZE option.
+You might want to do this if your pattern contains callouts or (*MARK) and you
+want to make use of these facilities in cases where matching fails.
+.P
+PCRE_NO_START_OPTIMIZE can be specified at either compile time or execution
+time. However, if PCRE_NO_START_OPTIMIZE is passed to \fBpcre_exec()\fP, (that
+is, after any JIT compilation has happened) JIT execution is disabled. For JIT
+execution to work with PCRE_NO_START_OPTIMIZE, the option must be set at
+compile time.
+.P
+There is a longer discussion of PCRE_NO_START_OPTIMIZE
+.\" HTML 
+.\" 
+below.
+.\"
+.
+.
+.\" HTML 
+.SH "LOCALE SUPPORT"
+.rs
+.sp
+PCRE handles caseless matching, and determines whether characters are letters,
+digits, or whatever, by reference to a set of tables, indexed by character
+code point. When running in UTF-8 mode, or in the 16- or 32-bit libraries, this
+applies only to characters with code points less than 256. By default,
+higher-valued code points never match escapes such as \ew or \ed. However, if
+PCRE is built with Unicode property support, all characters can be tested with
+\ep and \eP, or, alternatively, the PCRE_UCP option can be set when a pattern
+is compiled; this causes \ew and friends to use Unicode property support
+instead of the built-in tables.
+.P
+The use of locales with Unicode is discouraged. If you are handling characters
+with code points greater than 128, you should either use Unicode support, or
+use locales, but not try to mix the two.
+.P
+PCRE contains an internal set of tables that are used when the final argument
+of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
+Normally, the internal tables recognize only ASCII characters. However, when
+PCRE is built, it is possible to cause the internal tables to be rebuilt in the
+default "C" locale of the local system, which may cause them to be different.
+.P
+The internal tables can always be overridden by tables supplied by the
+application that calls PCRE. These may be created in a different locale from
+the default. As more and more applications change to using Unicode, the need
+for this locale support is expected to die away.
+.P
+External tables are built by calling the \fBpcre_maketables()\fP function,
+which has no arguments, in the relevant locale. The result can then be passed
+to \fBpcre_compile()\fP as often as necessary. For example, to build and use
+tables that are appropriate for the French locale (where accented characters
+with values greater than 128 are treated as letters), the following code could
+be used:
+.sp
+  setlocale(LC_CTYPE, "fr_FR");
+  tables = pcre_maketables();
+  re = pcre_compile(..., tables);
+.sp
+The locale name "fr_FR" is used on Linux and other Unix-like systems; if you
+are using Windows, the name for the French locale is "french".
+.P
+When \fBpcre_maketables()\fP runs, the tables are built in memory that is
+obtained via \fBpcre_malloc\fP. It is the caller's responsibility to ensure
+that the memory containing the tables remains available for as long as it is
+needed.
+.P
+The pointer that is passed to \fBpcre_compile()\fP is saved with the compiled
+pattern, and the same tables are used via this pointer by \fBpcre_study()\fP
+and also by \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP. Thus, for any single
+pattern, compilation, studying and matching all happen in the same locale, but
+different patterns can be processed in different locales.
+.P
+It is possible to pass a table pointer or NULL (indicating the use of the
+internal tables) to \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP (see the
+discussion below in the section on matching a pattern). This facility is
+provided for use with pre-compiled patterns that have been saved and reloaded.
+Character tables are not saved with patterns, so if a non-standard table was
+used at compile time, it must be provided again when the reloaded pattern is
+matched. Attempting to use this facility to match a pattern in a different
+locale from the one in which it was compiled is likely to lead to anomalous
+(usually incorrect) results.
+.
+.
+.\" HTML 
+.SH "INFORMATION ABOUT A PATTERN"
+.rs
+.sp
+.nf
+.B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     int \fIwhat\fP, void *\fIwhere\fP);"
+.fi
+.PP
+The \fBpcre_fullinfo()\fP function returns information about a compiled
+pattern. It replaces the \fBpcre_info()\fP function, which was removed from the
+library at version 8.30, after more than 10 years of obsolescence.
+.P
+The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled
+pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if
+the pattern was not studied. The third argument specifies which piece of
+information is required, and the fourth argument is a pointer to a variable
+to receive the data. The yield of the function is zero for success, or one of
+the following negative numbers:
+.sp
+  PCRE_ERROR_NULL           the argument \fIcode\fP was NULL
+                            the argument \fIwhere\fP was NULL
+  PCRE_ERROR_BADMAGIC       the "magic number" was not found
+  PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
+                            endianness
+  PCRE_ERROR_BADOPTION      the value of \fIwhat\fP was invalid
+  PCRE_ERROR_UNSET          the requested field is not set
+.sp
+The "magic number" is placed at the start of each compiled pattern as an simple
+check against passing an arbitrary memory pointer. The endianness error can
+occur if a compiled pattern is saved and reloaded on a different host. Here is
+a typical call of \fBpcre_fullinfo()\fP, to obtain the length of the compiled
+pattern:
+.sp
+  int rc;
+  size_t length;
+  rc = pcre_fullinfo(
+    re,               /* result of pcre_compile() */
+    sd,               /* result of pcre_study(), or NULL */
+    PCRE_INFO_SIZE,   /* what is required */
+    &length);         /* where to put the data */
+.sp
+The possible values for the third argument are defined in \fBpcre.h\fP, and are
+as follows:
+.sp
+  PCRE_INFO_BACKREFMAX
+.sp
+Return the number of the highest back reference in the pattern. The fourth
+argument should point to an \fBint\fP variable. Zero is returned if there are
+no back references.
+.sp
+  PCRE_INFO_CAPTURECOUNT
+.sp
+Return the number of capturing subpatterns in the pattern. The fourth argument
+should point to an \fBint\fP variable.
+.sp
+  PCRE_INFO_DEFAULT_TABLES
+.sp
+Return a pointer to the internal default character tables within PCRE. The
+fourth argument should point to an \fBunsigned char *\fP variable. This
+information call is provided for internal use by the \fBpcre_study()\fP
+function. External callers can cause PCRE to use its internal tables by passing
+a NULL table pointer.
+.sp
+  PCRE_INFO_FIRSTBYTE (deprecated)
+.sp
+Return information about the first data unit of any matched string, for a
+non-anchored pattern. The name of this option refers to the 8-bit library,
+where data units are bytes. The fourth argument should point to an \fBint\fP
+variable. Negative values are used for special cases. However, this means that
+when the 32-bit library is in non-UTF-32 mode, the full 32-bit range of
+characters cannot be returned. For this reason, this value is deprecated; use
+PCRE_INFO_FIRSTCHARACTERFLAGS and PCRE_INFO_FIRSTCHARACTER instead.
+.P
+If there is a fixed first value, for example, the letter "c" from a pattern
+such as (cat|cow|coyote), its value is returned. In the 8-bit library, the
+value is always less than 256. In the 16-bit library the value can be up to
+0xffff. In the 32-bit library the value can be up to 0x10ffff.
+.P
+If there is no fixed first value, and if either
+.sp
+(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
+starts with "^", or
+.sp
+(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
+(if it were set, the pattern would be anchored),
+.sp
+-1 is returned, indicating that the pattern matches only at the start of a
+subject string or after any newline within the string. Otherwise -2 is
+returned. For anchored patterns, -2 is returned.
+.sp
+  PCRE_INFO_FIRSTCHARACTER
+.sp
+Return the value of the first data unit (non-UTF character) of any matched
+string in the situation where PCRE_INFO_FIRSTCHARACTERFLAGS returns 1;
+otherwise return 0. The fourth argument should point to an \fBuint_t\fP
+variable.
+.P
+In the 8-bit library, the value is always less than 256. In the 16-bit library
+the value can be up to 0xffff. In the 32-bit library in UTF-32 mode the value
+can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32 mode.
+.sp
+  PCRE_INFO_FIRSTCHARACTERFLAGS
+.sp
+Return information about the first data unit of any matched string, for a
+non-anchored pattern. The fourth argument should point to an \fBint\fP
+variable.
+.P
+If there is a fixed first value, for example, the letter "c" from a pattern
+such as (cat|cow|coyote), 1 is returned, and the character value can be
+retrieved using PCRE_INFO_FIRSTCHARACTER. If there is no fixed first value, and
+if either
+.sp
+(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
+starts with "^", or
+.sp
+(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
+(if it were set, the pattern would be anchored),
+.sp
+2 is returned, indicating that the pattern matches only at the start of a
+subject string or after any newline within the string. Otherwise 0 is
+returned. For anchored patterns, 0 is returned.
+.sp
+  PCRE_INFO_FIRSTTABLE
+.sp
+If the pattern was studied, and this resulted in the construction of a 256-bit
+table indicating a fixed set of values for the first data unit in any matching
+string, a pointer to the table is returned. Otherwise NULL is returned. The
+fourth argument should point to an \fBunsigned char *\fP variable.
+.sp
+  PCRE_INFO_HASCRORLF
+.sp
+Return 1 if the pattern contains any explicit matches for CR or LF characters,
+otherwise 0. The fourth argument should point to an \fBint\fP variable. An
+explicit match is either a literal CR or LF character, or \er or \en.
+.sp
+  PCRE_INFO_JCHANGED
+.sp
+Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
+0. The fourth argument should point to an \fBint\fP variable. (?J) and
+(?-J) set and unset the local PCRE_DUPNAMES option, respectively.
+.sp
+  PCRE_INFO_JIT
+.sp
+Return 1 if the pattern was studied with one of the JIT options, and
+just-in-time compiling was successful. The fourth argument should point to an
+\fBint\fP variable. A return value of 0 means that JIT support is not available
+in this version of PCRE, or that the pattern was not studied with a JIT option,
+or that the JIT compiler could not handle this particular pattern. See the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation for details of what can and cannot be handled.
+.sp
+  PCRE_INFO_JITSIZE
+.sp
+If the pattern was successfully studied with a JIT option, return the size of
+the JIT compiled code, otherwise return zero. The fourth argument should point
+to a \fBsize_t\fP variable.
+.sp
+  PCRE_INFO_LASTLITERAL
+.sp
+Return the value of the rightmost literal data unit that must exist in any
+matched string, other than at its start, if such a value has been recorded. The
+fourth argument should point to an \fBint\fP variable. If there is no such
+value, -1 is returned. For anchored patterns, a last literal value is recorded
+only if it follows something of variable length. For example, for the pattern
+/^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
+is -1.
+.P
+Since for the 32-bit library using the non-UTF-32 mode, this function is unable
+to return the full 32-bit range of characters, this value is deprecated;
+instead the PCRE_INFO_REQUIREDCHARFLAGS and PCRE_INFO_REQUIREDCHAR values should
+be used.
+.sp
+  PCRE_INFO_MATCH_EMPTY
+.sp
+Return 1 if the pattern can match an empty string, otherwise 0. The fourth
+argument should point to an \fBint\fP variable.
+.sp
+  PCRE_INFO_MATCHLIMIT
+.sp
+If the pattern set a match limit by including an item of the form
+(*LIMIT_MATCH=nnnn) at the start, the value is returned. The fourth argument
+should point to an unsigned 32-bit integer. If no such value has been set, the
+call to \fBpcre_fullinfo()\fP returns the error PCRE_ERROR_UNSET.
+.sp
+  PCRE_INFO_MAXLOOKBEHIND
+.sp
+Return the number of characters (NB not data units) in the longest lookbehind
+assertion in the pattern. This information is useful when doing multi-segment
+matching using the partial matching facilities. Note that the simple assertions
+\eb and \eB require a one-character lookbehind. \eA also registers a
+one-character lookbehind, though it does not actually inspect the previous
+character. This is to ensure that at least one character from the old segment
+is retained when a new segment is processed. Otherwise, if there are no
+lookbehinds in the pattern, \eA might match incorrectly at the start of a new
+segment.
+.sp
+  PCRE_INFO_MINLENGTH
+.sp
+If the pattern was studied and a minimum length for matching subject strings
+was computed, its value is returned. Otherwise the returned value is -1. The
+value is a number of characters, which in UTF mode may be different from the
+number of data units. The fourth argument should point to an \fBint\fP
+variable. A non-negative value is a lower bound to the length of any matching
+string. There may not be any strings of that length that do actually match, but
+every string that does match is at least that long.
+.sp
+  PCRE_INFO_NAMECOUNT
+  PCRE_INFO_NAMEENTRYSIZE
+  PCRE_INFO_NAMETABLE
+.sp
+PCRE supports the use of named as well as numbered capturing parentheses. The
+names are just an additional way of identifying the parentheses, which still
+acquire numbers. Several convenience functions such as
+\fBpcre_get_named_substring()\fP are provided for extracting captured
+substrings by name. It is also possible to extract the data directly, by first
+converting the name to a number in order to access the correct pointers in the
+output vector (described with \fBpcre_exec()\fP below). To do the conversion,
+you need to use the name-to-number map, which is described by these three
+values.
+.P
+The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives
+the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each
+entry; both of these return an \fBint\fP value. The entry size depends on the
+length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first
+entry of the table. This is a pointer to \fBchar\fP in the 8-bit library, where
+the first two bytes of each entry are the number of the capturing parenthesis,
+most significant byte first. In the 16-bit library, the pointer points to
+16-bit data units, the first of which contains the parenthesis number. In the
+32-bit library, the pointer points to 32-bit data units, the first of which
+contains the parenthesis number. The rest of the entry is the corresponding
+name, zero terminated.
+.P
+The names are in alphabetical order. If (?| is used to create multiple groups
+with the same number, as described in the
+.\" HTML 
+.\" 
+section on duplicate subpattern numbers
+.\"
+in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+page, the groups may be given the same name, but there is only one entry in the
+table. Different names for groups of the same number are not permitted.
+Duplicate names for subpatterns with different numbers are permitted,
+but only if PCRE_DUPNAMES is set. They appear in the table in the order in
+which they were found in the pattern. In the absence of (?| this is the order
+of increasing number; when (?| is used this is not necessarily the case because
+later subpatterns may have lower numbers.
+.P
+As a simple example of the name/number table, consider the following pattern
+after compilation by the 8-bit library (assume PCRE_EXTENDED is set, so white
+space - including newlines - is ignored):
+.sp
+.\" JOIN
+  (? (?(\ed\ed)?\ed\ed) -
+  (?\ed\ed) - (?\ed\ed) )
+.sp
+There are four named subpatterns, so the table has four entries, and each entry
+in the table is eight bytes long. The table is as follows, with non-printing
+bytes shows in hexadecimal, and undefined bytes shown as ??:
+.sp
+  00 01 d  a  t  e  00 ??
+  00 05 d  a  y  00 ?? ??
+  00 04 m  o  n  t  h  00
+  00 02 y  e  a  r  00 ??
+.sp
+When writing code to extract data from named subpatterns using the
+name-to-number map, remember that the length of the entries is likely to be
+different for each compiled pattern.
+.sp
+  PCRE_INFO_OKPARTIAL
+.sp
+Return 1 if the pattern can be used for partial matching with
+\fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
+\fBint\fP variable. From release 8.00, this always returns 1, because the
+restrictions that previously applied to partial matching have been lifted. The
+.\" HREF
+\fBpcrepartial\fP
+.\"
+documentation gives details of partial matching.
+.sp
+  PCRE_INFO_OPTIONS
+.sp
+Return a copy of the options with which the pattern was compiled. The fourth
+argument should point to an \fBunsigned long int\fP variable. These option bits
+are those specified in the call to \fBpcre_compile()\fP, modified by any
+top-level option settings at the start of the pattern itself. In other words,
+they are the options that will be in force when matching starts. For example,
+if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
+result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
+.P
+A pattern is automatically anchored by PCRE if all of its top-level
+alternatives begin with one of the following:
+.sp
+  ^     unless PCRE_MULTILINE is set
+  \eA    always
+  \eG    always
+.\" JOIN
+  .*    if PCRE_DOTALL is set and there are no back
+          references to the subpattern in which .* appears
+.sp
+For such patterns, the PCRE_ANCHORED bit is set in the options returned by
+\fBpcre_fullinfo()\fP.
+.sp
+  PCRE_INFO_RECURSIONLIMIT
+.sp
+If the pattern set a recursion limit by including an item of the form
+(*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth
+argument should point to an unsigned 32-bit integer. If no such value has been
+set, the call to \fBpcre_fullinfo()\fP returns the error PCRE_ERROR_UNSET.
+.sp
+  PCRE_INFO_SIZE
+.sp
+Return the size of the compiled pattern in bytes (for all three libraries). The
+fourth argument should point to a \fBsize_t\fP variable. This value does not
+include the size of the \fBpcre\fP structure that is returned by
+\fBpcre_compile()\fP. The value that is passed as the argument to
+\fBpcre_malloc()\fP when \fBpcre_compile()\fP is getting memory in which to
+place the compiled data is the value returned by this option plus the size of
+the \fBpcre\fP structure. Studying a compiled pattern, with or without JIT,
+does not alter the value returned by this option.
+.sp
+  PCRE_INFO_STUDYSIZE
+.sp
+Return the size in bytes (for all three libraries) of the data block pointed to
+by the \fIstudy_data\fP field in a \fBpcre_extra\fP block. If \fBpcre_extra\fP
+is NULL, or there is no study data, zero is returned. The fourth argument
+should point to a \fBsize_t\fP variable. The \fIstudy_data\fP field is set by
+\fBpcre_study()\fP to record information that will speed up matching (see the
+section entitled
+.\" HTML 
+.\" 
+"Studying a pattern"
+.\"
+above). The format of the \fIstudy_data\fP block is private, but its length
+is made available via this option so that it can be saved and restored (see the
+.\" HREF
+\fBpcreprecompile\fP
+.\"
+documentation for details).
+.sp
+  PCRE_INFO_REQUIREDCHARFLAGS
+.sp
+Returns 1 if there is a rightmost literal data unit that must exist in any
+matched string, other than at its start. The fourth argument should  point to
+an \fBint\fP variable. If there is no such value, 0 is returned. If returning
+1, the character value itself can be retrieved using PCRE_INFO_REQUIREDCHAR.
+.P
+For anchored patterns, a last literal value is recorded only if it follows
+something of variable length. For example, for the pattern /^a\ed+z\ed+/ the
+returned value 1 (with "z" returned from PCRE_INFO_REQUIREDCHAR), but for
+/^a\edz\ed/ the returned value is 0.
+.sp
+  PCRE_INFO_REQUIREDCHAR
+.sp
+Return the value of the rightmost literal data unit that must exist in any
+matched string, other than at its start, if such a value has been recorded. The
+fourth argument should point to an \fBuint32_t\fP variable. If there is no such
+value, 0 is returned.
+.
+.
+.SH "REFERENCE COUNTS"
+.rs
+.sp
+.B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
+.PP
+The \fBpcre_refcount()\fP function is used to maintain a reference count in the
+data block that contains a compiled pattern. It is provided for the benefit of
+applications that operate in an object-oriented manner, where different parts
+of the application may be using the same compiled pattern, but you want to free
+the block when they are all done.
+.P
+When a pattern is compiled, the reference count field is initialized to zero.
+It is changed only by calling this function, whose action is to add the
+\fIadjust\fP value (which may be positive or negative) to it. The yield of the
+function is the new value. However, the value of the count is constrained to
+lie between 0 and 65535, inclusive. If the new value is outside these limits,
+it is forced to the appropriate limit value.
+.P
+Except when it is zero, the reference count is not correctly preserved if a
+pattern is compiled on one host and then transferred to a host whose byte-order
+is different. (This seems a highly unlikely scenario.)
+.
+.
+.SH "MATCHING A PATTERN: THE TRADITIONAL FUNCTION"
+.rs
+.sp
+.nf
+.B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);"
+.fi
+.P
+The function \fBpcre_exec()\fP is called to match a subject string against a
+compiled pattern, which is passed in the \fIcode\fP argument. If the
+pattern was studied, the result of the study should be passed in the
+\fIextra\fP argument. You can call \fBpcre_exec()\fP with the same \fIcode\fP
+and \fIextra\fP arguments as many times as you like, in order to match
+different subject strings with the same pattern.
+.P
+This function is the main matching facility of the library, and it operates in
+a Perl-like manner. For specialist use there is also an alternative matching
+function, which is described
+.\" HTML 
+.\" 
+below
+.\"
+in the section about the \fBpcre_dfa_exec()\fP function.
+.P
+In most applications, the pattern will have been compiled (and optionally
+studied) in the same process that calls \fBpcre_exec()\fP. However, it is
+possible to save compiled patterns and study data, and then use them later
+in different processes, possibly even on different hosts. For a discussion
+about this, see the
+.\" HREF
+\fBpcreprecompile\fP
+.\"
+documentation.
+.P
+Here is an example of a simple call to \fBpcre_exec()\fP:
+.sp
+  int rc;
+  int ovector[30];
+  rc = pcre_exec(
+    re,             /* result of pcre_compile() */
+    NULL,           /* we didn't study the pattern */
+    "some string",  /* the subject string */
+    11,             /* the length of the subject string */
+    0,              /* start at offset 0 in the subject */
+    0,              /* default options */
+    ovector,        /* vector of integers for substring information */
+    30);            /* number of elements (NOT size in bytes) */
+.
+.
+.\" HTML 
+.SS "Extra data for \fBpcre_exec()\fR"
+.rs
+.sp
+If the \fIextra\fP argument is not NULL, it must point to a \fBpcre_extra\fP
+data block. The \fBpcre_study()\fP function returns such a block (when it
+doesn't return NULL), but you can also create one for yourself, and pass
+additional information in it. The \fBpcre_extra\fP block contains the following
+fields (not necessarily in this order):
+.sp
+  unsigned long int \fIflags\fP;
+  void *\fIstudy_data\fP;
+  void *\fIexecutable_jit\fP;
+  unsigned long int \fImatch_limit\fP;
+  unsigned long int \fImatch_limit_recursion\fP;
+  void *\fIcallout_data\fP;
+  const unsigned char *\fItables\fP;
+  unsigned char **\fImark\fP;
+.sp
+In the 16-bit version of this structure, the \fImark\fP field has type
+"PCRE_UCHAR16 **".
+.sp
+In the 32-bit version of this structure, the \fImark\fP field has type
+"PCRE_UCHAR32 **".
+.P
+The \fIflags\fP field is used to specify which of the other fields are set. The
+flag bits are:
+.sp
+  PCRE_EXTRA_CALLOUT_DATA
+  PCRE_EXTRA_EXECUTABLE_JIT
+  PCRE_EXTRA_MARK
+  PCRE_EXTRA_MATCH_LIMIT
+  PCRE_EXTRA_MATCH_LIMIT_RECURSION
+  PCRE_EXTRA_STUDY_DATA
+  PCRE_EXTRA_TABLES
+.sp
+Other flag bits should be set to zero. The \fIstudy_data\fP field and sometimes
+the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
+returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
+should not set these yourself, but you may add to the block by setting other
+fields and their corresponding flag bits.
+.P
+The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
+vast amount of resources when running patterns that are not going to match,
+but which have a very large number of possibilities in their search trees. The
+classic example is a pattern that uses nested unlimited repeats.
+.P
+Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
+calls repeatedly (sometimes recursively). The limit set by \fImatch_limit\fP is
+imposed on the number of times this function is called during a match, which
+has the effect of limiting the amount of backtracking that can take place. For
+patterns that are not anchored, the count restarts from zero for each position
+in the subject string.
+.P
+When \fBpcre_exec()\fP is called with a pattern that was successfully studied
+with a JIT option, the way that the matching is executed is entirely different.
+However, there is still the possibility of runaway matching that goes on for a
+very long time, and so the \fImatch_limit\fP value is also used in this case
+(but in a different way) to limit how long the matching can continue.
+.P
+The default value for the limit can be set when PCRE is built; the default
+default is 10 million, which handles all but the most extreme cases. You can
+override the default by suppling \fBpcre_exec()\fP with a \fBpcre_extra\fP
+block in which \fImatch_limit\fP is set, and PCRE_EXTRA_MATCH_LIMIT is set in
+the \fIflags\fP field. If the limit is exceeded, \fBpcre_exec()\fP returns
+PCRE_ERROR_MATCHLIMIT.
+.P
+A value for the match limit may also be supplied by an item at the start of a
+pattern of the form
+.sp
+  (*LIMIT_MATCH=d)
+.sp
+where d is a decimal number. However, such a setting is ignored unless d is
+less than the limit set by the caller of \fBpcre_exec()\fP or, if no such limit
+is set, less than the default.
+.P
+The \fImatch_limit_recursion\fP field is similar to \fImatch_limit\fP, but
+instead of limiting the total number of times that \fBmatch()\fP is called, it
+limits the depth of recursion. The recursion depth is a smaller number than the
+total number of calls, because not all calls to \fBmatch()\fP are recursive.
+This limit is of use only if it is set smaller than \fImatch_limit\fP.
+.P
+Limiting the recursion depth limits the amount of machine stack that can be
+used, or, when PCRE has been compiled to use memory on the heap instead of the
+stack, the amount of heap memory that can be used. This limit is not relevant,
+and is ignored, when matching is done using JIT compiled code.
+.P
+The default value for \fImatch_limit_recursion\fP can be set when PCRE is
+built; the default default is the same value as the default for
+\fImatch_limit\fP. You can override the default by suppling \fBpcre_exec()\fP
+with a \fBpcre_extra\fP block in which \fImatch_limit_recursion\fP is set, and
+PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
+is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
+.P
+A value for the recursion limit may also be supplied by an item at the start of
+a pattern of the form
+.sp
+  (*LIMIT_RECURSION=d)
+.sp
+where d is a decimal number. However, such a setting is ignored unless d is
+less than the limit set by the caller of \fBpcre_exec()\fP or, if no such limit
+is set, less than the default.
+.P
+The \fIcallout_data\fP field is used in conjunction with the "callout" feature,
+and is described in the
+.\" HREF
+\fBpcrecallout\fP
+.\"
+documentation.
+.P
+The \fItables\fP field is provided for use with patterns that have been
+pre-compiled using custom character tables, saved to disc or elsewhere, and
+then reloaded, because the tables that were used to compile a pattern are not
+saved with it. See the
+.\" HREF
+\fBpcreprecompile\fP
+.\"
+documentation for a discussion of saving compiled patterns for later use. If
+NULL is passed using this mechanism, it forces PCRE's internal tables to be
+used.
+.P
+\fBWarning:\fP The tables that \fBpcre_exec()\fP uses must be the same as those
+that were used when the pattern was compiled. If this is not the case, the
+behaviour of \fBpcre_exec()\fP is undefined. Therefore, when a pattern is
+compiled and matched in the same process, this field should never be set. In
+this (the most common) case, the correct table pointer is automatically passed
+with the compiled pattern from \fBpcre_compile()\fP to \fBpcre_exec()\fP.
+.P
+If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
+be set to point to a suitable variable. If the pattern contains any
+backtracking control verbs such as (*MARK:NAME), and the execution ends up with
+a name to pass back, a pointer to the name string (zero terminated) is placed
+in the variable pointed to by the \fImark\fP field. The names are within the
+compiled pattern; if you wish to retain such a name you must copy it before
+freeing the memory of a compiled pattern. If there is no name to pass back, the
+variable pointed to by the \fImark\fP field is set to NULL. For details of the
+backtracking control verbs, see the section entitled
+.\" HTML 
+.\" 
+"Backtracking control"
+.\"
+in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+documentation.
+.
+.
+.\" HTML 
+.SS "Option bits for \fBpcre_exec()\fP"
+.rs
+.sp
+The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
+zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
+PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
+PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and
+PCRE_PARTIAL_SOFT.
+.P
+If the pattern was successfully studied with one of the just-in-time (JIT)
+compile options, the only supported options for JIT execution are
+PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
+PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
+unsupported option is used, JIT execution is disabled and the normal
+interpretive code in \fBpcre_exec()\fP is run.
+.sp
+  PCRE_ANCHORED
+.sp
+The PCRE_ANCHORED option limits \fBpcre_exec()\fP to matching at the first
+matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
+to be anchored by virtue of its contents, it cannot be made unachored at
+matching time.
+.sp
+  PCRE_BSR_ANYCRLF
+  PCRE_BSR_UNICODE
+.sp
+These options (which are mutually exclusive) control what the \eR escape
+sequence matches. The choice is either to match only CR, LF, or CRLF, or to
+match any Unicode newline sequence. These options override the choice that was
+made or defaulted when the pattern was compiled.
+.sp
+  PCRE_NEWLINE_CR
+  PCRE_NEWLINE_LF
+  PCRE_NEWLINE_CRLF
+  PCRE_NEWLINE_ANYCRLF
+  PCRE_NEWLINE_ANY
+.sp
+These options override the newline definition that was chosen or defaulted when
+the pattern was compiled. For details, see the description of
+\fBpcre_compile()\fP above. During matching, the newline choice affects the
+behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
+the way the match position is advanced after a match failure for an unanchored
+pattern.
+.P
+When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
+match attempt for an unanchored pattern fails when the current position is at a
+CRLF sequence, and the pattern contains no explicit matches for CR or LF
+characters, the match position is advanced by two characters instead of one, in
+other words, to after the CRLF.
+.P
+The above rule is a compromise that makes the most common cases work as
+expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
+set), it does not match the string "\er\enA" because, after failing at the
+start, it skips both the CR and the LF before retrying. However, the pattern
+[\er\en]A does match that string, because it contains an explicit CR or LF
+reference, and so advances only by one character after the first failure.
+.P
+An explicit match for CR of LF is either a literal appearance of one of those
+characters, or one of the \er or \en escape sequences. Implicit matches such as
+[^X] do not count, nor does \es (which includes CR and LF in the characters
+that it matches).
+.P
+Notwithstanding the above, anomalous effects may still occur when CRLF is a
+valid newline sequence and explicit \er or \en escapes appear in the pattern.
+.sp
+  PCRE_NOTBOL
+.sp
+This option specifies that first character of the subject string is not the
+beginning of a line, so the circumflex metacharacter should not match before
+it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
+never to match. This option affects only the behaviour of the circumflex
+metacharacter. It does not affect \eA.
+.sp
+  PCRE_NOTEOL
+.sp
+This option specifies that the end of the subject string is not the end of a
+line, so the dollar metacharacter should not match it nor (except in multiline
+mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at
+compile time) causes dollar never to match. This option affects only the
+behaviour of the dollar metacharacter. It does not affect \eZ or \ez.
+.sp
+  PCRE_NOTEMPTY
+.sp
+An empty string is not considered to be a valid match if this option is set. If
+there are alternatives in the pattern, they are tried. If all the alternatives
+match the empty string, the entire match fails. For example, if the pattern
+.sp
+  a?b?
+.sp
+is applied to a string not beginning with "a" or "b", it matches an empty
+string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
+valid, so PCRE searches further into the string for occurrences of "a" or "b".
+.sp
+  PCRE_NOTEMPTY_ATSTART
+.sp
+This is like PCRE_NOTEMPTY, except that an empty string match that is not at
+the start of the subject is permitted. If the pattern is anchored, such a match
+can occur only if the pattern contains \eK.
+.P
+Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
+does make a special case of a pattern match of the empty string within its
+\fBsplit()\fP function, and when using the /g modifier. It is possible to
+emulate Perl's behaviour after matching a null string by first trying the match
+again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
+if that fails, by advancing the starting offset (see below) and trying an
+ordinary match again. There is some code that demonstrates how to do this in
+the
+.\" HREF
+\fBpcredemo\fP
+.\"
+sample program. In the most general case, you have to check to see if the
+newline convention recognizes CRLF as a newline, and if so, and the current
+character is CR followed by LF, advance the starting offset by two characters
+instead of one.
+.sp
+  PCRE_NO_START_OPTIMIZE
+.sp
+There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
+a match, in order to speed up the process. For example, if it is known that an
+unanchored match must start with a specific character, it searches the subject
+for that character, and fails immediately if it cannot find it, without
+actually running the main matching function. This means that a special item
+such as (*COMMIT) at the start of a pattern is not considered until after a
+suitable starting point for the match has been found. Also, when callouts or
+(*MARK) items are in use, these "start-up" optimizations can cause them to be
+skipped if the pattern is never actually used. The start-up optimizations are
+in effect a pre-scan of the subject that takes place before the pattern is run.
+.P
+The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
+causing performance to suffer, but ensuring that in cases where the result is
+"no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
+are considered at every possible starting position in the subject string. If
+PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
+time. The use of PCRE_NO_START_OPTIMIZE at matching time (that is, passing it
+to \fBpcre_exec()\fP) disables JIT execution; in this situation, matching is
+always done using interpretively.
+.P
+Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
+Consider the pattern
+.sp
+  (*COMMIT)ABC
+.sp
+When this is compiled, PCRE records the fact that a match must start with the
+character "A". Suppose the subject string is "DEFABC". The start-up
+optimization scans along the subject, finds "A" and runs the first match
+attempt from there. The (*COMMIT) item means that the pattern must match the
+current starting position, which in this case, it does. However, if the same
+match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
+subject string does not happen. The first match attempt is run starting from
+"D" and when this fails, (*COMMIT) prevents any further matches being tried, so
+the overall result is "no match". If the pattern is studied, more start-up
+optimizations may be used. For example, a minimum length for the subject may be
+recorded. Consider the pattern
+.sp
+  (*MARK:A)(X|Y)
+.sp
+The minimum length for a match is one character. If the subject is "ABC", there
+will be attempts to match "ABC", "BC", "C", and then finally an empty string.
+If the pattern is studied, the final attempt does not take place, because PCRE
+knows that the subject is too short, and so the (*MARK) is never encountered.
+In this case, studying the pattern does not affect the overall match result,
+which is still "no match", but it does affect the auxiliary information that is
+returned.
+.sp
+  PCRE_NO_UTF8_CHECK
+.sp
+When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
+string is automatically checked when \fBpcre_exec()\fP is subsequently called.
+The entire string is checked before any other processing takes place. The value
+of \fIstartoffset\fP is also checked to ensure that it points to the start of a
+UTF-8 character. There is a discussion about the
+.\" HTML 
+.\" 
+validity of UTF-8 strings
+.\"
+in the
+.\" HREF
+\fBpcreunicode\fP
+.\"
+page. If an invalid sequence of bytes is found, \fBpcre_exec()\fP returns the
+error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
+truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In both
+cases, information about the precise nature of the error may also be returned
+(see the descriptions of these errors in the section entitled \fIError return
+values from\fP \fBpcre_exec()\fP
+.\" HTML 
+.\" 
+below).
+.\"
+If \fIstartoffset\fP contains a value that does not point to the start of a
+UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
+returned.
+.P
+If you already know that your subject is valid, and you want to skip these
+checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
+calling \fBpcre_exec()\fP. You might want to do this for the second and
+subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
+all the matches in a single subject string. However, you should be sure that
+the value of \fIstartoffset\fP points to the start of a character (or the end
+of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
+invalid string as a subject or an invalid value of \fIstartoffset\fP is
+undefined. Your program may crash or loop.
+.sp
+  PCRE_PARTIAL_HARD
+  PCRE_PARTIAL_SOFT
+.sp
+These options turn on the partial matching feature. For backwards
+compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
+occurs if the end of the subject string is reached successfully, but there are
+not enough subject characters to complete the match. If this happens when
+PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
+testing any remaining alternatives. Only if no complete match can be found is
+PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
+PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
+but only if no complete match can be found.
+.P
+If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
+partial match is found, \fBpcre_exec()\fP immediately returns
+PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
+when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
+important that an alternative complete match.
+.P
+In both cases, the portion of the string that was inspected when the partial
+match was found is set as the first matching string. There is a more detailed
+discussion of partial and multi-segment matching, with examples, in the
+.\" HREF
+\fBpcrepartial\fP
+.\"
+documentation.
+.
+.
+.SS "The string to be matched by \fBpcre_exec()\fP"
+.rs
+.sp
+The subject string is passed to \fBpcre_exec()\fP as a pointer in
+\fIsubject\fP, a length in \fIlength\fP, and a starting offset in
+\fIstartoffset\fP. The units for \fIlength\fP and \fIstartoffset\fP are bytes
+for the 8-bit library, 16-bit data items for the 16-bit library, and 32-bit
+data items for the 32-bit library.
+.P
+If \fIstartoffset\fP is negative or greater than the length of the subject,
+\fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting offset is
+zero, the search for a match starts at the beginning of the subject, and this
+is by far the most common case. In UTF-8 or UTF-16 mode, the offset must point
+to the start of a character, or the end of the subject (in UTF-32 mode, one
+data unit equals one character, so all offsets are valid). Unlike the pattern
+string, the subject may contain binary zeroes.
+.P
+A non-zero starting offset is useful when searching for another match in the
+same subject by calling \fBpcre_exec()\fP again after a previous success.
+Setting \fIstartoffset\fP differs from just passing over a shortened string and
+setting PCRE_NOTBOL in the case of a pattern that begins with any kind of
+lookbehind. For example, consider the pattern
+.sp
+  \eBiss\eB
+.sp
+which finds occurrences of "iss" in the middle of words. (\eB matches only if
+the current position in the subject is not a word boundary.) When applied to
+the string "Mississipi" the first call to \fBpcre_exec()\fP finds the first
+occurrence. If \fBpcre_exec()\fP is called again with just the remainder of the
+subject, namely "issipi", it does not match, because \eB is always false at the
+start of the subject, which is deemed to be a word boundary. However, if
+\fBpcre_exec()\fP is passed the entire string again, but with \fIstartoffset\fP
+set to 4, it finds the second occurrence of "iss" because it is able to look
+behind the starting point to discover that it is preceded by a letter.
+.P
+Finding all the matches in a subject is tricky when the pattern can match an
+empty string. It is possible to emulate Perl's /g behaviour by first trying the
+match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
+PCRE_ANCHORED options, and then if that fails, advancing the starting offset
+and trying an ordinary match again. There is some code that demonstrates how to
+do this in the
+.\" HREF
+\fBpcredemo\fP
+.\"
+sample program. In the most general case, you have to check to see if the
+newline convention recognizes CRLF as a newline, and if so, and the current
+character is CR followed by LF, advance the starting offset by two characters
+instead of one.
+.P
+If a non-zero starting offset is passed when the pattern is anchored, one
+attempt to match at the given offset is made. This can only succeed if the
+pattern does not require the match to be at the start of the subject.
+.
+.
+.SS "How \fBpcre_exec()\fP returns captured substrings"
+.rs
+.sp
+In general, a pattern matches a certain portion of the subject, and in
+addition, further substrings from the subject may be picked out by parts of the
+pattern. Following the usage in Jeffrey Friedl's book, this is called
+"capturing" in what follows, and the phrase "capturing subpattern" is used for
+a fragment of a pattern that picks out a substring. PCRE supports several other
+kinds of parenthesized subpattern that do not cause substrings to be captured.
+.P
+Captured substrings are returned to the caller via a vector of integers whose
+address is passed in \fIovector\fP. The number of elements in the vector is
+passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP: this
+argument is NOT the size of \fIovector\fP in bytes.
+.P
+The first two-thirds of the vector is used to pass back captured substrings,
+each substring using a pair of integers. The remaining third of the vector is
+used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
+and is not available for passing back information. The number passed in
+\fIovecsize\fP should always be a multiple of three. If it is not, it is
+rounded down.
+.P
+When a match is successful, information about captured substrings is returned
+in pairs of integers, starting at the beginning of \fIovector\fP, and
+continuing up to two-thirds of its length at the most. The first element of
+each pair is set to the offset of the first character in a substring, and the
+second is set to the offset of the first character after the end of a
+substring. These values are always data unit offsets, even in UTF mode. They
+are byte offsets in the 8-bit library, 16-bit data item offsets in the 16-bit
+library, and 32-bit data item offsets in the 32-bit library. \fBNote\fP: they
+are not character counts.
+.P
+The first pair of integers, \fIovector[0]\fP and \fIovector[1]\fP, identify the
+portion of the subject string matched by the entire pattern. The next pair is
+used for the first capturing subpattern, and so on. The value returned by
+\fBpcre_exec()\fP is one more than the highest numbered pair that has been set.
+For example, if two substrings have been captured, the returned value is 3. If
+there are no capturing subpatterns, the return value from a successful match is
+1, indicating that just the first pair of offsets has been set.
+.P
+If a capturing subpattern is matched repeatedly, it is the last portion of the
+string that it matched that is returned.
+.P
+If the vector is too small to hold all the captured substring offsets, it is
+used as far as possible (up to two-thirds of its length), and the function
+returns a value of zero. If neither the actual string matched nor any captured
+substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP
+passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains
+back references and the \fIovector\fP is not big enough to remember the related
+substrings, PCRE has to get additional memory for use during matching. Thus it
+is usually advisable to supply an \fIovector\fP of reasonable size.
+.P
+There are some cases where zero is returned (indicating vector overflow) when
+in fact the vector is exactly the right size for the final match. For example,
+consider the pattern
+.sp
+  (a)(?:(b)c|bd)
+.sp
+If a vector of 6 elements (allowing for only 1 captured substring) is given
+with subject string "abd", \fBpcre_exec()\fP will try to set the second
+captured string, thereby recording a vector overflow, before failing to match
+"c" and backing up to try the second alternative. The zero return, however,
+does correctly indicate that the maximum number of slots (namely 2) have been
+filled. In similar cases where there is temporary overflow, but the final
+number of used slots is actually less than the maximum, a non-zero value is
+returned.
+.P
+The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
+subpatterns there are in a compiled pattern. The smallest size for
+\fIovector\fP that will allow for \fIn\fP captured substrings, in addition to
+the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.
+.P
+It is possible for capturing subpattern number \fIn+1\fP to match some part of
+the subject when subpattern \fIn\fP has not been used at all. For example, if
+the string "abc" is matched against the pattern (a|(z))(bc) the return from the
+function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
+happens, both values in the offset pairs corresponding to unused subpatterns
+are set to -1.
+.P
+Offset values that correspond to unused subpatterns at the end of the
+expression are also set to -1. For example, if the string "abc" is matched
+against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
+return from the function is 2, because the highest used capturing subpattern
+number is 1, and the offsets for for the second and third capturing subpatterns
+(assuming the vector is large enough, of course) are set to -1.
+.P
+\fBNote\fP: Elements in the first two-thirds of \fIovector\fP that do not
+correspond to capturing parentheses in the pattern are never changed. That is,
+if a pattern contains \fIn\fP capturing parentheses, no more than
+\fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
+elements (in the first two-thirds) retain whatever values they previously had.
+.P
+Some convenience functions are provided for extracting the captured substrings
+as separate strings. These are described below.
+.
+.
+.\" HTML 
+.SS "Error return values from \fBpcre_exec()\fP"
+.rs
+.sp
+If \fBpcre_exec()\fP fails, it returns a negative number. The following are
+defined in the header file:
+.sp
+  PCRE_ERROR_NOMATCH        (-1)
+.sp
+The subject string did not match the pattern.
+.sp
+  PCRE_ERROR_NULL           (-2)
+.sp
+Either \fIcode\fP or \fIsubject\fP was passed as NULL, or \fIovector\fP was
+NULL and \fIovecsize\fP was not zero.
+.sp
+  PCRE_ERROR_BADOPTION      (-3)
+.sp
+An unrecognized bit was set in the \fIoptions\fP argument.
+.sp
+  PCRE_ERROR_BADMAGIC       (-4)
+.sp
+PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch
+the case when it is passed a junk pointer and to detect when a pattern that was
+compiled in an environment of one endianness is run in an environment with the
+other endianness. This is the error that PCRE gives when the magic number is
+not present.
+.sp
+  PCRE_ERROR_UNKNOWN_OPCODE (-5)
+.sp
+While running the pattern match, an unknown item was encountered in the
+compiled pattern. This error could be caused by a bug in PCRE or by overwriting
+of the compiled pattern.
+.sp
+  PCRE_ERROR_NOMEMORY       (-6)
+.sp
+If a pattern contains back references, but the \fIovector\fP that is passed to
+\fBpcre_exec()\fP is not big enough to remember the referenced substrings, PCRE
+gets a block of memory at the start of matching to use for this purpose. If the
+call via \fBpcre_malloc()\fP fails, this error is given. The memory is
+automatically freed at the end of matching.
+.P
+This error is also given if \fBpcre_stack_malloc()\fP fails in
+\fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
+\fB--disable-stack-for-recursion\fP.
+.sp
+  PCRE_ERROR_NOSUBSTRING    (-7)
+.sp
+This error is used by the \fBpcre_copy_substring()\fP,
+\fBpcre_get_substring()\fP, and \fBpcre_get_substring_list()\fP functions (see
+below). It is never returned by \fBpcre_exec()\fP.
+.sp
+  PCRE_ERROR_MATCHLIMIT     (-8)
+.sp
+The backtracking limit, as specified by the \fImatch_limit\fP field in a
+\fBpcre_extra\fP structure (or defaulted) was reached. See the description
+above.
+.sp
+  PCRE_ERROR_CALLOUT        (-9)
+.sp
+This error is never generated by \fBpcre_exec()\fP itself. It is provided for
+use by callout functions that want to yield a distinctive error code. See the
+.\" HREF
+\fBpcrecallout\fP
+.\"
+documentation for details.
+.sp
+  PCRE_ERROR_BADUTF8        (-10)
+.sp
+A string that contains an invalid UTF-8 byte sequence was passed as a subject,
+and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
+(\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
+UTF-8 character is placed in the first element, and a reason code is placed in
+the second element. The reason codes are listed in the
+.\" HTML 
+.\" 
+following section.
+.\"
+For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
+truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
+PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
+.sp
+  PCRE_ERROR_BADUTF8_OFFSET (-11)
+.sp
+The UTF-8 byte sequence that was passed as a subject was checked and found to
+be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
+\fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
+end of the subject.
+.sp
+  PCRE_ERROR_PARTIAL        (-12)
+.sp
+The subject string did not match, but it did match partially. See the
+.\" HREF
+\fBpcrepartial\fP
+.\"
+documentation for details of partial matching.
+.sp
+  PCRE_ERROR_BADPARTIAL     (-13)
+.sp
+This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
+option was used with a compiled pattern containing items that were not
+supported for partial matching. From release 8.00 onwards, there are no
+restrictions on partial matching.
+.sp
+  PCRE_ERROR_INTERNAL       (-14)
+.sp
+An unexpected internal error has occurred. This error could be caused by a bug
+in PCRE or by overwriting of the compiled pattern.
+.sp
+  PCRE_ERROR_BADCOUNT       (-15)
+.sp
+This error is given if the value of the \fIovecsize\fP argument is negative.
+.sp
+  PCRE_ERROR_RECURSIONLIMIT (-21)
+.sp
+The internal recursion limit, as specified by the \fImatch_limit_recursion\fP
+field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
+description above.
+.sp
+  PCRE_ERROR_BADNEWLINE     (-23)
+.sp
+An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
+.sp
+  PCRE_ERROR_BADOFFSET      (-24)
+.sp
+The value of \fIstartoffset\fP was negative or greater than the length of the
+subject, that is, the value in \fIlength\fP.
+.sp
+  PCRE_ERROR_SHORTUTF8      (-25)
+.sp
+This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
+ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
+Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
+fact sufficient to detect this case, but this special error code for
+PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
+retained for backwards compatibility.
+.sp
+  PCRE_ERROR_RECURSELOOP    (-26)
+.sp
+This error is returned when \fBpcre_exec()\fP detects a recursion loop within
+the pattern. Specifically, it means that either the whole pattern or a
+subpattern has been called recursively for the second time at the same position
+in the subject string. Some simple patterns that might do this are detected and
+faulted at compile time, but more complicated cases, in particular mutual
+recursions between two different subpatterns, cannot be detected until run
+time.
+.sp
+  PCRE_ERROR_JIT_STACKLIMIT (-27)
+.sp
+This error is returned when a pattern that was successfully studied using a
+JIT compile option is being matched, but the memory available for the
+just-in-time processing stack is not large enough. See the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation for more details.
+.sp
+  PCRE_ERROR_BADMODE        (-28)
+.sp
+This error is given if a pattern that was compiled by the 8-bit library is
+passed to a 16-bit or 32-bit library function, or vice versa.
+.sp
+  PCRE_ERROR_BADENDIANNESS  (-29)
+.sp
+This error is given if a pattern that was compiled and saved is reloaded on a
+host with different endianness. The utility function
+\fBpcre_pattern_to_host_byte_order()\fP can be used to convert such a pattern
+so that it runs on the new host.
+.sp
+  PCRE_ERROR_JIT_BADOPTION
+.sp
+This error is returned when a pattern that was successfully studied using a JIT
+compile option is being matched, but the matching mode (partial or complete
+match) does not correspond to any JIT compilation mode. When the JIT fast path
+function is used, this error may be also given for invalid options. See the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation for more details.
+.sp
+  PCRE_ERROR_BADLENGTH      (-32)
+.sp
+This error is given if \fBpcre_exec()\fP is called with a negative value for
+the \fIlength\fP argument.
+.P
+Error numbers -16 to -20, -22, and 30 are not used by \fBpcre_exec()\fP.
+.
+.
+.\" HTML 
+.SS "Reason codes for invalid UTF-8 strings"
+.rs
+.sp
+This section applies only to the 8-bit library. The corresponding information
+for the 16-bit and 32-bit libraries is given in the
+.\" HREF
+\fBpcre16\fP
+.\"
+and
+.\" HREF
+\fBpcre32\fP
+.\"
+pages.
+.P
+When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
+PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
+least 2, the offset of the start of the invalid UTF-8 character is placed in
+the first output vector element (\fIovector[0]\fP) and a reason code is placed
+in the second element (\fIovector[1]\fP). The reason codes are given names in
+the \fBpcre.h\fP header file:
+.sp
+  PCRE_UTF8_ERR1
+  PCRE_UTF8_ERR2
+  PCRE_UTF8_ERR3
+  PCRE_UTF8_ERR4
+  PCRE_UTF8_ERR5
+.sp
+The string ends with a truncated UTF-8 character; the code specifies how many
+bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
+no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
+allows for up to 6 bytes, and this is checked first; hence the possibility of
+4 or 5 missing bytes.
+.sp
+  PCRE_UTF8_ERR6
+  PCRE_UTF8_ERR7
+  PCRE_UTF8_ERR8
+  PCRE_UTF8_ERR9
+  PCRE_UTF8_ERR10
+.sp
+The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
+character do not have the binary value 0b10 (that is, either the most
+significant bit is 0, or the next bit is 1).
+.sp
+  PCRE_UTF8_ERR11
+  PCRE_UTF8_ERR12
+.sp
+A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
+these code points are excluded by RFC 3629.
+.sp
+  PCRE_UTF8_ERR13
+.sp
+A 4-byte character has a value greater than 0x10fff; these code points are
+excluded by RFC 3629.
+.sp
+  PCRE_UTF8_ERR14
+.sp
+A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
+code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
+from UTF-8.
+.sp
+  PCRE_UTF8_ERR15
+  PCRE_UTF8_ERR16
+  PCRE_UTF8_ERR17
+  PCRE_UTF8_ERR18
+  PCRE_UTF8_ERR19
+.sp
+A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
+value that can be represented by fewer bytes, which is invalid. For example,
+the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
+one byte.
+.sp
+  PCRE_UTF8_ERR20
+.sp
+The two most significant bits of the first byte of a character have the binary
+value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
+byte can only validly occur as the second or subsequent byte of a multi-byte
+character.
+.sp
+  PCRE_UTF8_ERR21
+.sp
+The first byte of a character has the value 0xfe or 0xff. These values can
+never occur in a valid UTF-8 string.
+.sp
+  PCRE_UTF8_ERR22
+.sp
+This error code was formerly used when the presence of a so-called
+"non-character" caused an error. Unicode corrigendum #9 makes it clear that
+such characters should not cause a string to be rejected, and so this code is
+no longer in use and is never returned.
+.
+.
+.SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
+.rs
+.sp
+.nf
+.B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,"
+.B "     int \fIbuffersize\fP);"
+.sp
+.B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
+.B "     int \fIstringcount\fP, int \fIstringnumber\fP,"
+.B "     const char **\fIstringptr\fP);"
+.sp
+.B int pcre_get_substring_list(const char *\fIsubject\fP,
+.B "     int *\fIovector\fP, int \fIstringcount\fP, const char ***\fIlistptr\fP);"
+.fi
+.PP
+Captured substrings can be accessed directly by using the offsets returned by
+\fBpcre_exec()\fP in \fIovector\fP. For convenience, the functions
+\fBpcre_copy_substring()\fP, \fBpcre_get_substring()\fP, and
+\fBpcre_get_substring_list()\fP are provided for extracting captured substrings
+as new, separate, zero-terminated strings. These functions identify substrings
+by number. The next section describes functions for extracting named
+substrings.
+.P
+A substring that contains a binary zero is correctly extracted and has a
+further zero added on the end, but the result is not, of course, a C string.
+However, you can process such a string by referring to the length that is
+returned by \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP.
+Unfortunately, the interface to \fBpcre_get_substring_list()\fP is not adequate
+for handling strings containing binary zeros, because the end of the final
+string is not independently indicated.
+.P
+The first three arguments are the same for all three of these functions:
+\fIsubject\fP is the subject string that has just been successfully matched,
+\fIovector\fP is a pointer to the vector of integer offsets that was passed to
+\fBpcre_exec()\fP, and \fIstringcount\fP is the number of substrings that were
+captured by the match, including the substring that matched the entire regular
+expression. This is the value returned by \fBpcre_exec()\fP if it is greater
+than zero. If \fBpcre_exec()\fP returned zero, indicating that it ran out of
+space in \fIovector\fP, the value passed as \fIstringcount\fP should be the
+number of elements in the vector divided by three.
+.P
+The functions \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP
+extract a single substring, whose number is given as \fIstringnumber\fP. A
+value of zero extracts the substring that matched the entire pattern, whereas
+higher values extract the captured substrings. For \fBpcre_copy_substring()\fP,
+the string is placed in \fIbuffer\fP, whose length is given by
+\fIbuffersize\fP, while for \fBpcre_get_substring()\fP a new block of memory is
+obtained via \fBpcre_malloc\fP, and its address is returned via
+\fIstringptr\fP. The yield of the function is the length of the string, not
+including the terminating zero, or one of these error codes:
+.sp
+  PCRE_ERROR_NOMEMORY       (-6)
+.sp
+The buffer was too small for \fBpcre_copy_substring()\fP, or the attempt to get
+memory failed for \fBpcre_get_substring()\fP.
+.sp
+  PCRE_ERROR_NOSUBSTRING    (-7)
+.sp
+There is no substring whose number is \fIstringnumber\fP.
+.P
+The \fBpcre_get_substring_list()\fP function extracts all available substrings
+and builds a list of pointers to them. All this is done in a single block of
+memory that is obtained via \fBpcre_malloc\fP. The address of the memory block
+is returned via \fIlistptr\fP, which is also the start of the list of string
+pointers. The end of the list is marked by a NULL pointer. The yield of the
+function is zero if all went well, or the error code
+.sp
+  PCRE_ERROR_NOMEMORY       (-6)
+.sp
+if the attempt to get the memory block failed.
+.P
+When any of these functions encounter a substring that is unset, which can
+happen when capturing subpattern number \fIn+1\fP matches some part of the
+subject, but subpattern \fIn\fP has not been used at all, they return an empty
+string. This can be distinguished from a genuine zero-length substring by
+inspecting the appropriate offset in \fIovector\fP, which is negative for unset
+substrings.
+.P
+The two convenience functions \fBpcre_free_substring()\fP and
+\fBpcre_free_substring_list()\fP can be used to free the memory returned by
+a previous call of \fBpcre_get_substring()\fP or
+\fBpcre_get_substring_list()\fP, respectively. They do nothing more than call
+the function pointed to by \fBpcre_free\fP, which of course could be called
+directly from a C program. However, PCRE is used in some situations where it is
+linked via a special interface to another programming language that cannot use
+\fBpcre_free\fP directly; it is for these cases that the functions are
+provided.
+.
+.
+.SH "EXTRACTING CAPTURED SUBSTRINGS BY NAME"
+.rs
+.sp
+.nf
+.B int pcre_get_stringnumber(const pcre *\fIcode\fP,
+.B "     const char *\fIname\fP);"
+.sp
+.B int pcre_copy_named_substring(const pcre *\fIcode\fP,
+.B "     const char *\fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, const char *\fIstringname\fP,"
+.B "     char *\fIbuffer\fP, int \fIbuffersize\fP);"
+.sp
+.B int pcre_get_named_substring(const pcre *\fIcode\fP,
+.B "     const char *\fIsubject\fP, int *\fIovector\fP,"
+.B "     int \fIstringcount\fP, const char *\fIstringname\fP,"
+.B "     const char **\fIstringptr\fP);"
+.fi
+.PP
+To extract a substring by name, you first have to find associated number.
+For example, for this pattern
+.sp
+  (a+)b(?\ed+)...
+.sp
+the number of the subpattern called "xxx" is 2. If the name is known to be
+unique (PCRE_DUPNAMES was not set), you can find the number from the name by
+calling \fBpcre_get_stringnumber()\fP. The first argument is the compiled
+pattern, and the second is the name. The yield of the function is the
+subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
+that name.
+.P
+Given the number, you can extract the substring directly, or use one of the
+functions described in the previous section. For convenience, there are also
+two functions that do the whole job.
+.P
+Most of the arguments of \fBpcre_copy_named_substring()\fP and
+\fBpcre_get_named_substring()\fP are the same as those for the similarly named
+functions that extract by number. As these are described in the previous
+section, they are not re-described here. There are just two differences:
+.P
+First, instead of a substring number, a substring name is given. Second, there
+is an extra argument, given at the start, which is a pointer to the compiled
+pattern. This is needed in order to gain access to the name-to-number
+translation table.
+.P
+These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they
+then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
+appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
+the behaviour may not be what you want (see the next section).
+.P
+\fBWarning:\fP If the pattern uses the (?| feature to set up multiple
+subpatterns with the same number, as described in the
+.\" HTML 
+.\" 
+section on duplicate subpattern numbers
+.\"
+in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+page, you cannot use names to distinguish the different subpatterns, because
+names are not included in the compiled code. The matching process uses only
+numbers. For this reason, the use of different names for subpatterns of the
+same number causes an error at compile time.
+.
+.
+.SH "DUPLICATE SUBPATTERN NAMES"
+.rs
+.sp
+.nf
+.B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
+.B "     const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);"
+.fi
+.PP
+When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
+are not required to be unique. (Duplicate names are always allowed for
+subpatterns with the same number, created by using the (?| feature. Indeed, if
+such subpatterns are named, they are required to use the same names.)
+.P
+Normally, patterns with duplicate names are such that in any one match, only
+one of the named subpatterns participates. An example is shown in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+documentation.
+.P
+When duplicates are present, \fBpcre_copy_named_substring()\fP and
+\fBpcre_get_named_substring()\fP return the first substring corresponding to
+the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
+returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
+returns one of the numbers that are associated with the name, but it is not
+defined which it is.
+.P
+If you want to get full details of all captured substrings for a given name,
+you must use the \fBpcre_get_stringtable_entries()\fP function. The first
+argument is the compiled pattern, and the second is the name. The third and
+fourth are pointers to variables which are updated by the function. After it
+has run, they point to the first and last entries in the name-to-number table
+for the given name. The function itself returns the length of each entry, or
+PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
+described above in the section entitled \fIInformation about a pattern\fP
+.\" HTML 
+.\" 
+above.
+.\"
+Given all the relevant entries for the name, you can extract each of their
+numbers, and hence the captured data, if any.
+.
+.
+.SH "FINDING ALL POSSIBLE MATCHES"
+.rs
+.sp
+The traditional matching function uses a similar algorithm to Perl, which stops
+when it finds the first match, starting at a given point in the subject. If you
+want to find all possible matches, or the longest possible match, consider
+using the alternative matching function (see below) instead. If you cannot use
+the alternative function, but still need to find all possible matches, you
+can kludge it up by making use of the callout facility, which is described in
+the
+.\" HREF
+\fBpcrecallout\fP
+.\"
+documentation.
+.P
+What you have to do is to insert a callout right at the end of the pattern.
+When your callout function is called, extract and save the current matched
+substring. Then return 1, which forces \fBpcre_exec()\fP to backtrack and try
+other alternatives. Ultimately, when it runs out of matches, \fBpcre_exec()\fP
+will yield PCRE_ERROR_NOMATCH.
+.
+.
+.SH "OBTAINING AN ESTIMATE OF STACK USAGE"
+.rs
+.sp
+Matching certain patterns using \fBpcre_exec()\fP can use a lot of process
+stack, which in certain environments can be rather limited in size. Some users
+find it helpful to have an estimate of the amount of stack that is used by
+\fBpcre_exec()\fP, to help them set recursion limits, as described in the
+.\" HREF
+\fBpcrestack\fP
+.\"
+documentation. The estimate that is output by \fBpcretest\fP when called with
+the \fB-m\fP and \fB-C\fP options is obtained by calling \fBpcre_exec\fP with
+the values NULL, NULL, NULL, -999, and -999 for its first five arguments.
+.P
+Normally, if its first argument is NULL, \fBpcre_exec()\fP immediately returns
+the negative error code PCRE_ERROR_NULL, but with this special combination of
+arguments, it returns instead a negative number whose absolute value is the
+approximate stack frame size in bytes. (A negative number is used so that it is
+clear that no match has happened.) The value is approximate because in some
+cases, recursive calls to \fBpcre_exec()\fP occur when there are one or two
+additional variables on the stack.
+.P
+If PCRE has been compiled to use the heap instead of the stack for recursion,
+the value returned is the size of each block that is obtained from the heap.
+.
+.
+.\" HTML 
+.SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
+.rs
+.sp
+.nf
+.B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
+.B "     const char *\fIsubject\fP, int \fIlength\fP, int \fIstartoffset\fP,"
+.B "     int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,"
+.B "     int *\fIworkspace\fP, int \fIwscount\fP);"
+.fi
+.P
+The function \fBpcre_dfa_exec()\fP is called to match a subject string against
+a compiled pattern, using a matching algorithm that scans the subject string
+just once, and does not backtrack. This has different characteristics to the
+normal algorithm, and is not compatible with Perl. Some of the features of PCRE
+patterns are not supported. Nevertheless, there are times when this kind of
+matching can be useful. For a discussion of the two matching algorithms, and a
+list of features that \fBpcre_dfa_exec()\fP does not support, see the
+.\" HREF
+\fBpcrematching\fP
+.\"
+documentation.
+.P
+The arguments for the \fBpcre_dfa_exec()\fP function are the same as for
+\fBpcre_exec()\fP, plus two extras. The \fIovector\fP argument is used in a
+different way, and this is described below. The other common arguments are used
+in the same way as for \fBpcre_exec()\fP, so their description is not repeated
+here.
+.P
+The two additional arguments provide workspace for the function. The workspace
+vector should contain at least 20 elements. It is used for keeping track of
+multiple paths through the pattern tree. More workspace will be needed for
+patterns and subjects where there are a lot of potential matches.
+.P
+Here is an example of a simple call to \fBpcre_dfa_exec()\fP:
+.sp
+  int rc;
+  int ovector[10];
+  int wspace[20];
+  rc = pcre_dfa_exec(
+    re,             /* result of pcre_compile() */
+    NULL,           /* we didn't study the pattern */
+    "some string",  /* the subject string */
+    11,             /* the length of the subject string */
+    0,              /* start at offset 0 in the subject */
+    0,              /* default options */
+    ovector,        /* vector of integers for substring information */
+    10,             /* number of elements (NOT size in bytes) */
+    wspace,         /* working space vector */
+    20);            /* number of elements (NOT size in bytes) */
+.
+.SS "Option bits for \fBpcre_dfa_exec()\fP"
+.rs
+.sp
+The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be
+zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
+PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
+PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
+PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
+All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
+so their description is not repeated here.
+.sp
+  PCRE_PARTIAL_HARD
+  PCRE_PARTIAL_SOFT
+.sp
+These have the same general effect as they do for \fBpcre_exec()\fP, but the
+details are slightly different. When PCRE_PARTIAL_HARD is set for
+\fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
+is reached and there is still at least one matching possibility that requires
+additional characters. This happens even if some complete matches have also
+been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
+is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
+there have been no complete matches, but there is still at least one matching
+possibility. The portion of the string that was inspected when the longest
+partial match was found is set as the first matching string in both cases.
+There is a more detailed discussion of partial and multi-segment matching, with
+examples, in the
+.\" HREF
+\fBpcrepartial\fP
+.\"
+documentation.
+.sp
+  PCRE_DFA_SHORTEST
+.sp
+Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
+soon as it has found one match. Because of the way the alternative algorithm
+works, this is necessarily the shortest possible match at the first possible
+matching point in the subject string.
+.sp
+  PCRE_DFA_RESTART
+.sp
+When \fBpcre_dfa_exec()\fP returns a partial match, it is possible to call it
+again, with additional subject characters, and have it continue with the same
+match. The PCRE_DFA_RESTART option requests this action; when it is set, the
+\fIworkspace\fP and \fIwscount\fP options must reference the same vector as
+before because data about the match so far is left in them after a partial
+match. There is more discussion of this facility in the
+.\" HREF
+\fBpcrepartial\fP
+.\"
+documentation.
+.
+.
+.SS "Successful returns from \fBpcre_dfa_exec()\fP"
+.rs
+.sp
+When \fBpcre_dfa_exec()\fP succeeds, it may have matched more than one
+substring in the subject. Note, however, that all the matches from one run of
+the function start at the same point in the subject. The shorter matches are
+all initial substrings of the longer matches. For example, if the pattern
+.sp
+  <.*>
+.sp
+is matched against the string
+.sp
+  This is    no more
+.sp
+the three matched strings are
+.sp
+  
+   
+    
+.sp
+On success, the yield of the function is a number greater than zero, which is
+the number of matched substrings. The substrings themselves are returned in
+\fIovector\fP. Each string uses two elements; the first is the offset to the
+start, and the second is the offset to the end. In fact, all the strings have
+the same start offset. (Space could have been saved by giving this only once,
+but it was decided to retain some compatibility with the way \fBpcre_exec()\fP
+returns data, even though the meaning of the strings is different.)
+.P
+The strings are returned in reverse order of length; that is, the longest
+matching string is given first. If there were too many matches to fit into
+\fIovector\fP, the yield of the function is zero, and the vector is filled with
+the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
+the entire \fIovector\fP for returning matched strings.
+.P
+NOTE: PCRE's "auto-possessification" optimization usually applies to character
+repeats at the end of a pattern (as well as internally). For example, the
+pattern "a\ed+" is compiled as if it were "a\ed++" because there is no point
+even considering the possibility of backtracking into the repeated digits. For
+DFA matching, this means that only one possible match is found. If you really
+do want multiple matches in such cases, either use an ungreedy repeat
+("a\ed+?") or set the PCRE_NO_AUTO_POSSESS option when compiling.
+.
+.
+.SS "Error returns from \fBpcre_dfa_exec()\fP"
+.rs
+.sp
+The \fBpcre_dfa_exec()\fP function returns a negative number when it fails.
+Many of the errors are the same as for \fBpcre_exec()\fP, and these are
+described
+.\" HTML 
+.\" 
+above.
+.\"
+There are in addition the following errors that are specific to
+\fBpcre_dfa_exec()\fP:
+.sp
+  PCRE_ERROR_DFA_UITEM      (-16)
+.sp
+This return is given if \fBpcre_dfa_exec()\fP encounters an item in the pattern
+that it does not support, for instance, the use of \eC or a back reference.
+.sp
+  PCRE_ERROR_DFA_UCOND      (-17)
+.sp
+This return is given if \fBpcre_dfa_exec()\fP encounters a condition item that
+uses a back reference for the condition, or a test for recursion in a specific
+group. These are not supported.
+.sp
+  PCRE_ERROR_DFA_UMLIMIT    (-18)
+.sp
+This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
+block that contains a setting of the \fImatch_limit\fP or
+\fImatch_limit_recursion\fP fields. This is not supported (these fields are
+meaningless for DFA matching).
+.sp
+  PCRE_ERROR_DFA_WSSIZE     (-19)
+.sp
+This return is given if \fBpcre_dfa_exec()\fP runs out of space in the
+\fIworkspace\fP vector.
+.sp
+  PCRE_ERROR_DFA_RECURSE    (-20)
+.sp
+When a recursive subpattern is processed, the matching function calls itself
+recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
+error is given if the output vector is not large enough. This should be
+extremely rare, as a vector of size 1000 is used.
+.sp
+  PCRE_ERROR_DFA_BADRESTART (-30)
+.sp
+When \fBpcre_dfa_exec()\fP is called with the \fBPCRE_DFA_RESTART\fP option,
+some plausibility checks are made on the contents of the workspace, which
+should contain data about the previous partial match. If any of these checks
+fail, this error is given.
+.
+.
+.SH "SEE ALSO"
+.rs
+.sp
+\fBpcre16\fP(3), \fBpcre32\fP(3), \fBpcrebuild\fP(3), \fBpcrecallout\fP(3),
+\fBpcrecpp(3)\fP(3), \fBpcrematching\fP(3), \fBpcrepartial\fP(3),
+\fBpcreposix\fP(3), \fBpcreprecompile\fP(3), \fBpcresample\fP(3),
+\fBpcrestack\fP(3).
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 09 February 2014
+Copyright (c) 1997-2014 University of Cambridge.
+.fi
diff --git a/doc/pcrebuild.3 b/doc/pcrebuild.3
new file mode 100644
index 0000000..403f2ae
--- /dev/null
+++ b/doc/pcrebuild.3
@@ -0,0 +1,550 @@
+.TH PCREBUILD 3 "12 May 2013" "PCRE 8.33"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.
+.
+.SH "BUILDING PCRE"
+.rs
+.sp
+PCRE is distributed with a \fBconfigure\fP script that can be used to build the
+library in Unix-like environments using the applications known as Autotools.
+Also in the distribution are files to support building using \fBCMake\fP
+instead of \fBconfigure\fP. The text file
+.\" HTML 
+.\" 
+\fBREADME\fP
+.\"
+contains general information about building with Autotools (some of which is
+repeated below), and also has some comments about building on various operating
+systems. There is a lot more information about building PCRE without using
+Autotools (including information about using \fBCMake\fP and building "by
+hand") in the text file called
+.\" HTML 
+.\" 
+\fBNON-AUTOTOOLS-BUILD\fP.
+.\"
+You should consult this file as well as the
+.\" HTML 
+.\" 
+\fBREADME\fP
+.\"
+file if you are building in a non-Unix-like environment.
+.
+.
+.SH "PCRE BUILD-TIME OPTIONS"
+.rs
+.sp
+The rest of this document describes the optional features of PCRE that can be
+selected when the library is compiled. It assumes use of the \fBconfigure\fP
+script, where the optional features are selected or deselected by providing
+options to \fBconfigure\fP before running the \fBmake\fP command. However, the
+same options can be selected in both Unix-like and non-Unix-like environments
+using the GUI facility of \fBcmake-gui\fP if you are using \fBCMake\fP instead
+of \fBconfigure\fP to build PCRE.
+.P
+If you are not using Autotools or \fBCMake\fP, option selection can be done by
+editing the \fBconfig.h\fP file, or by passing parameter settings to the
+compiler, as described in
+.\" HTML 
+.\" 
+\fBNON-AUTOTOOLS-BUILD\fP.
+.\"
+.P
+The complete list of options for \fBconfigure\fP (which includes the standard
+ones such as the selection of the installation directory) can be obtained by
+running
+.sp
+  ./configure --help
+.sp
+The following sections include descriptions of options whose names begin with
+--enable or --disable. These settings specify changes to the defaults for the
+\fBconfigure\fP command. Because of the way that \fBconfigure\fP works,
+--enable and --disable always come in pairs, so the complementary option always
+exists as well, but as it specifies the default, it is not described.
+.
+.
+.SH "BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES"
+.rs
+.sp
+By default, a library called \fBlibpcre\fP is built, containing functions that
+take string arguments contained in vectors of bytes, either as single-byte
+characters, or interpreted as UTF-8 strings. You can also build a separate
+library, called \fBlibpcre16\fP, in which strings are contained in vectors of
+16-bit data units and interpreted either as single-unit characters or UTF-16
+strings, by adding
+.sp
+  --enable-pcre16
+.sp
+to the \fBconfigure\fP command. You can also build yet another separate
+library, called \fBlibpcre32\fP, in which strings are contained in vectors of
+32-bit data units and interpreted either as single-unit characters or UTF-32
+strings, by adding
+.sp
+  --enable-pcre32
+.sp
+to the \fBconfigure\fP command. If you do not want the 8-bit library, add
+.sp
+  --disable-pcre8
+.sp
+as well. At least one of the three libraries must be built. Note that the C++
+and POSIX wrappers are for the 8-bit library only, and that \fBpcregrep\fP is
+an 8-bit program. None of these are built if you select only the 16-bit or
+32-bit libraries.
+.
+.
+.SH "BUILDING SHARED AND STATIC LIBRARIES"
+.rs
+.sp
+The Autotools PCRE building process uses \fBlibtool\fP to build both shared and
+static libraries by default. You can suppress one of these by adding one of
+.sp
+  --disable-shared
+  --disable-static
+.sp
+to the \fBconfigure\fP command, as required.
+.
+.
+.SH "C++ SUPPORT"
+.rs
+.sp
+By default, if the 8-bit library is being built, the \fBconfigure\fP script
+will search for a C++ compiler and C++ header files. If it finds them, it
+automatically builds the C++ wrapper library (which supports only 8-bit
+strings). You can disable this by adding
+.sp
+  --disable-cpp
+.sp
+to the \fBconfigure\fP command.
+.
+.
+.SH "UTF-8, UTF-16 AND UTF-32 SUPPORT"
+.rs
+.sp
+To build PCRE with support for UTF Unicode character strings, add
+.sp
+  --enable-utf
+.sp
+to the \fBconfigure\fP command. This setting applies to all three libraries,
+adding support for UTF-8 to the 8-bit library, support for UTF-16 to the 16-bit
+library, and support for UTF-32 to the to the 32-bit library. There are no
+separate options for enabling UTF-8, UTF-16 and UTF-32 independently because
+that would allow ridiculous settings such as requesting UTF-16 support while
+building only the 8-bit library. It is not possible to build one library with
+UTF support and another without in the same configuration. (For backwards
+compatibility, --enable-utf8 is a synonym of --enable-utf.)
+.P
+Of itself, this setting does not make PCRE treat strings as UTF-8, UTF-16 or
+UTF-32. As well as compiling PCRE with this option, you also have have to set
+the PCRE_UTF8, PCRE_UTF16 or PCRE_UTF32 option (as appropriate) when you call
+one of the pattern compiling functions.
+.P
+If you set --enable-utf when compiling in an EBCDIC environment, PCRE expects
+its input to be either ASCII or UTF-8 (depending on the run-time option). It is
+not possible to support both EBCDIC and UTF-8 codes in the same version of the
+library. Consequently, --enable-utf and --enable-ebcdic are mutually
+exclusive.
+.
+.
+.SH "UNICODE CHARACTER PROPERTY SUPPORT"
+.rs
+.sp
+UTF support allows the libraries to process character codepoints up to 0x10ffff
+in the strings that they handle. On its own, however, it does not provide any
+facilities for accessing the properties of such characters. If you want to be
+able to use the pattern escapes \eP, \ep, and \eX, which refer to Unicode
+character properties, you must add
+.sp
+  --enable-unicode-properties
+.sp
+to the \fBconfigure\fP command. This implies UTF support, even if you have
+not explicitly requested it.
+.P
+Including Unicode property support adds around 30K of tables to the PCRE
+library. Only the general category properties such as \fILu\fP and \fINd\fP are
+supported. Details are given in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+documentation.
+.
+.
+.SH "JUST-IN-TIME COMPILER SUPPORT"
+.rs
+.sp
+Just-in-time compiler support is included in the build by specifying
+.sp
+  --enable-jit
+.sp
+This support is available only for certain hardware architectures. If this
+option is set for an unsupported architecture, a compile time error occurs.
+See the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation for a discussion of JIT usage. When JIT support is enabled,
+pcregrep automatically makes use of it, unless you add
+.sp
+  --disable-pcregrep-jit
+.sp
+to the "configure" command.
+.
+.
+.SH "CODE VALUE OF NEWLINE"
+.rs
+.sp
+By default, PCRE interprets the linefeed (LF) character as indicating the end
+of a line. This is the normal newline character on Unix-like systems. You can
+compile PCRE to use carriage return (CR) instead, by adding
+.sp
+  --enable-newline-is-cr
+.sp
+to the \fBconfigure\fP command. There is also a --enable-newline-is-lf option,
+which explicitly specifies linefeed as the newline character.
+.sp
+Alternatively, you can specify that line endings are to be indicated by the two
+character sequence CRLF. If you want this, add
+.sp
+  --enable-newline-is-crlf
+.sp
+to the \fBconfigure\fP command. There is a fourth option, specified by
+.sp
+  --enable-newline-is-anycrlf
+.sp
+which causes PCRE to recognize any of the three sequences CR, LF, or CRLF as
+indicating a line ending. Finally, a fifth option, specified by
+.sp
+  --enable-newline-is-any
+.sp
+causes PCRE to recognize any Unicode newline sequence.
+.P
+Whatever line ending convention is selected when PCRE is built can be
+overridden when the library functions are called. At build time it is
+conventional to use the standard for your operating system.
+.
+.
+.SH "WHAT \eR MATCHES"
+.rs
+.sp
+By default, the sequence \eR in a pattern matches any Unicode newline sequence,
+whatever has been selected as the line ending sequence. If you specify
+.sp
+  --enable-bsr-anycrlf
+.sp
+the default is changed so that \eR matches only CR, LF, or CRLF. Whatever is
+selected when PCRE is built can be overridden when the library functions are
+called.
+.
+.
+.SH "POSIX MALLOC USAGE"
+.rs
+.sp
+When the 8-bit library is called through the POSIX interface (see the
+.\" HREF
+\fBpcreposix\fP
+.\"
+documentation), additional working storage is required for holding the pointers
+to capturing substrings, because PCRE requires three integers per substring,
+whereas the POSIX interface provides only two. If the number of expected
+substrings is small, the wrapper function uses space on the stack, because this
+is faster than using \fBmalloc()\fP for each call. The default threshold above
+which the stack is no longer used is 10; it can be changed by adding a setting
+such as
+.sp
+  --with-posix-malloc-threshold=20
+.sp
+to the \fBconfigure\fP command.
+.
+.
+.SH "HANDLING VERY LARGE PATTERNS"
+.rs
+.sp
+Within a compiled pattern, offset values are used to point from one part to
+another (for example, from an opening parenthesis to an alternation
+metacharacter). By default, in the 8-bit and 16-bit libraries, two-byte values
+are used for these offsets, leading to a maximum size for a compiled pattern of
+around 64K. This is sufficient to handle all but the most gigantic patterns.
+Nevertheless, some people do want to process truly enormous patterns, so it is
+possible to compile PCRE to use three-byte or four-byte offsets by adding a
+setting such as
+.sp
+  --with-link-size=3
+.sp
+to the \fBconfigure\fP command. The value given must be 2, 3, or 4. For the
+16-bit library, a value of 3 is rounded up to 4. In these libraries, using
+longer offsets slows down the operation of PCRE because it has to load
+additional data when handling them. For the 32-bit library the value is always
+4 and cannot be overridden; the value of --with-link-size is ignored.
+.
+.
+.SH "AVOIDING EXCESSIVE STACK USAGE"
+.rs
+.sp
+When matching with the \fBpcre_exec()\fP function, PCRE implements backtracking
+by making recursive calls to an internal function called \fBmatch()\fP. In
+environments where the size of the stack is limited, this can severely limit
+PCRE's operation. (The Unix environment does not usually suffer from this
+problem, but it may sometimes be necessary to increase the maximum stack size.
+There is a discussion in the
+.\" HREF
+\fBpcrestack\fP
+.\"
+documentation.) An alternative approach to recursion that uses memory from the
+heap to remember data, instead of using recursive function calls, has been
+implemented to work round the problem of limited stack size. If you want to
+build a version of PCRE that works this way, add
+.sp
+  --disable-stack-for-recursion
+.sp
+to the \fBconfigure\fP command. With this configuration, PCRE will use the
+\fBpcre_stack_malloc\fP and \fBpcre_stack_free\fP variables to call memory
+management functions. By default these point to \fBmalloc()\fP and
+\fBfree()\fP, but you can replace the pointers so that your own functions are
+used instead.
+.P
+Separate functions are provided rather than using \fBpcre_malloc\fP and
+\fBpcre_free\fP because the usage is very predictable: the block sizes
+requested are always the same, and the blocks are always freed in reverse
+order. A calling program might be able to implement optimized functions that
+perform better than \fBmalloc()\fP and \fBfree()\fP. PCRE runs noticeably more
+slowly when built in this way. This option affects only the \fBpcre_exec()\fP
+function; it is not relevant for \fBpcre_dfa_exec()\fP.
+.
+.
+.SH "LIMITING PCRE RESOURCE USAGE"
+.rs
+.sp
+Internally, PCRE has a function called \fBmatch()\fP, which it calls repeatedly
+(sometimes recursively) when matching a pattern with the \fBpcre_exec()\fP
+function. By controlling the maximum number of times this function may be
+called during a single matching operation, a limit can be placed on the
+resources used by a single call to \fBpcre_exec()\fP. The limit can be changed
+at run time, as described in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation. The default is 10 million, but this can be changed by adding a
+setting such as
+.sp
+  --with-match-limit=500000
+.sp
+to the \fBconfigure\fP command. This setting has no effect on the
+\fBpcre_dfa_exec()\fP matching function.
+.P
+In some environments it is desirable to limit the depth of recursive calls of
+\fBmatch()\fP more strictly than the total number of calls, in order to
+restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
+is specified) that is used. A second limit controls this; it defaults to the
+value that is set for --with-match-limit, which imposes no additional
+constraints. However, you can set a lower limit by adding, for example,
+.sp
+  --with-match-limit-recursion=10000
+.sp
+to the \fBconfigure\fP command. This value can also be overridden at run time.
+.
+.
+.SH "CREATING CHARACTER TABLES AT BUILD TIME"
+.rs
+.sp
+PCRE uses fixed tables for processing characters whose code values are less
+than 256. By default, PCRE is built with a set of tables that are distributed
+in the file \fIpcre_chartables.c.dist\fP. These tables are for ASCII codes
+only. If you add
+.sp
+  --enable-rebuild-chartables
+.sp
+to the \fBconfigure\fP command, the distributed tables are no longer used.
+Instead, a program called \fBdftables\fP is compiled and run. This outputs the
+source for new set of tables, created in the default locale of your C run-time
+system. (This method of replacing the tables does not work if you are cross
+compiling, because \fBdftables\fP is run on the local host. If you need to
+create alternative tables when cross compiling, you will have to do so "by
+hand".)
+.
+.
+.SH "USING EBCDIC CODE"
+.rs
+.sp
+PCRE assumes by default that it will run in an environment where the character
+code is ASCII (or Unicode, which is a superset of ASCII). This is the case for
+most computer operating systems. PCRE can, however, be compiled to run in an
+EBCDIC environment by adding
+.sp
+  --enable-ebcdic
+.sp
+to the \fBconfigure\fP command. This setting implies
+--enable-rebuild-chartables. You should only use it if you know that you are in
+an EBCDIC environment (for example, an IBM mainframe operating system). The
+--enable-ebcdic option is incompatible with --enable-utf.
+.P
+The EBCDIC character that corresponds to an ASCII LF is assumed to have the
+value 0x15 by default. However, in some EBCDIC environments, 0x25 is used. In
+such an environment you should use
+.sp
+  --enable-ebcdic-nl25
+.sp
+as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR has the
+same value as in ASCII, namely, 0x0d. Whichever of 0x15 and 0x25 is \fInot\fP
+chosen as LF is made to correspond to the Unicode NEL character (which, in
+Unicode, is 0x85).
+.P
+The options that select newline behaviour, such as --enable-newline-is-cr,
+and equivalent run-time options, refer to these character values in an EBCDIC
+environment.
+.
+.
+.SH "PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT"
+.rs
+.sp
+By default, \fBpcregrep\fP reads all files as plain text. You can build it so
+that it recognizes files whose names end in \fB.gz\fP or \fB.bz2\fP, and reads
+them with \fBlibz\fP or \fBlibbz2\fP, respectively, by adding one or both of
+.sp
+  --enable-pcregrep-libz
+  --enable-pcregrep-libbz2
+.sp
+to the \fBconfigure\fP command. These options naturally require that the
+relevant libraries are installed on your system. Configuration will fail if
+they are not.
+.
+.
+.SH "PCREGREP BUFFER SIZE"
+.rs
+.sp
+\fBpcregrep\fP uses an internal buffer to hold a "window" on the file it is
+scanning, in order to be able to output "before" and "after" lines when it
+finds a match. The size of the buffer is controlled by a parameter whose
+default value is 20K. The buffer itself is three times this size, but because
+of the way it is used for holding "before" lines, the longest line that is
+guaranteed to be processable is the parameter size. You can change the default
+parameter value by adding, for example,
+.sp
+  --with-pcregrep-bufsize=50K
+.sp
+to the \fBconfigure\fP command. The caller of \fPpcregrep\fP can, however,
+override this value by specifying a run-time option.
+.
+.
+.SH "PCRETEST OPTION FOR LIBREADLINE SUPPORT"
+.rs
+.sp
+If you add
+.sp
+  --enable-pcretest-libreadline
+.sp
+to the \fBconfigure\fP command, \fBpcretest\fP is linked with the
+\fBlibreadline\fP library, and when its input is from a terminal, it reads it
+using the \fBreadline()\fP function. This provides line-editing and history
+facilities. Note that \fBlibreadline\fP is GPL-licensed, so if you distribute a
+binary of \fBpcretest\fP linked in this way, there may be licensing issues.
+.P
+Setting this option causes the \fB-lreadline\fP option to be added to the
+\fBpcretest\fP build. In many operating environments with a sytem-installed
+\fBlibreadline\fP this is sufficient. However, in some environments (e.g.
+if an unmodified distribution version of readline is in use), some extra
+configuration may be necessary. The INSTALL file for \fBlibreadline\fP says
+this:
+.sp
+  "Readline uses the termcap functions, but does not link with the
+  termcap or curses library itself, allowing applications which link
+  with readline the to choose an appropriate library."
+.sp
+If your environment has not been set up so that an appropriate library is
+automatically included, you may need to add something like
+.sp
+  LIBS="-ncurses"
+.sp
+immediately before the \fBconfigure\fP command.
+.
+.
+.SH "DEBUGGING WITH VALGRIND SUPPORT"
+.rs
+.sp
+By adding the
+.sp
+  --enable-valgrind
+.sp
+option to to the \fBconfigure\fP command, PCRE will use valgrind annotations
+to mark certain memory regions as unaddressable. This allows it to detect
+invalid memory accesses, and is mostly useful for debugging PCRE itself.
+.
+.
+.SH "CODE COVERAGE REPORTING"
+.rs
+.sp
+If your C compiler is gcc, you can build a version of PCRE that can generate a
+code coverage report for its test suite. To enable this, you must install
+\fBlcov\fP version 1.6 or above. Then specify
+.sp
+  --enable-coverage
+.sp
+to the \fBconfigure\fP command and build PCRE in the usual way.
+.P
+Note that using \fBccache\fP (a caching C compiler) is incompatible with code
+coverage reporting. If you have configured \fBccache\fP to run automatically
+on your system, you must set the environment variable
+.sp
+  CCACHE_DISABLE=1
+.sp
+before running \fBmake\fP to build PCRE, so that \fBccache\fP is not used.
+.P
+When --enable-coverage is used, the following addition targets are added to the
+\fIMakefile\fP:
+.sp
+  make coverage
+.sp
+This creates a fresh coverage report for the PCRE test suite. It is equivalent
+to running "make coverage-reset", "make coverage-baseline", "make check", and
+then "make coverage-report".
+.sp
+  make coverage-reset
+.sp
+This zeroes the coverage counters, but does nothing else.
+.sp
+  make coverage-baseline
+.sp
+This captures baseline coverage information.
+.sp
+  make coverage-report
+.sp
+This creates the coverage report.
+.sp
+  make coverage-clean-report
+.sp
+This removes the generated coverage report without cleaning the coverage data
+itself.
+.sp
+  make coverage-clean-data
+.sp
+This removes the captured coverage data without removing the coverage files
+created at compile time (*.gcno).
+.sp
+  make coverage-clean
+.sp
+This cleans all coverage data including the generated coverage report. For more
+information about code coverage, see the \fBgcov\fP and \fBlcov\fP
+documentation.
+.
+.
+.SH "SEE ALSO"
+.rs
+.sp
+\fBpcreapi\fP(3), \fBpcre16\fP, \fBpcre32\fP, \fBpcre_config\fP(3).
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 12 May 2013
+Copyright (c) 1997-2013 University of Cambridge.
+.fi
diff --git a/doc/pcrecallout.3 b/doc/pcrecallout.3
new file mode 100644
index 0000000..8ebc995
--- /dev/null
+++ b/doc/pcrecallout.3
@@ -0,0 +1,255 @@
+.TH PCRECALLOUT 3 "12 November 2013" "PCRE 8.34"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH SYNOPSIS
+.rs
+.sp
+.B #include 
+.PP
+.SM
+.B int (*pcre_callout)(pcre_callout_block *);
+.PP
+.B int (*pcre16_callout)(pcre16_callout_block *);
+.PP
+.B int (*pcre32_callout)(pcre32_callout_block *);
+.
+.SH DESCRIPTION
+.rs
+.sp
+PCRE provides a feature called "callout", which is a means of temporarily
+passing control to the caller of PCRE in the middle of pattern matching. The
+caller of PCRE provides an external function by putting its entry point in the
+global variable \fIpcre_callout\fP (\fIpcre16_callout\fP for the 16-bit
+library, \fIpcre32_callout\fP for the 32-bit library). By default, this
+variable contains NULL, which disables all calling out.
+.P
+Within a regular expression, (?C) indicates the points at which the external
+function is to be called. Different callout points can be identified by putting
+a number less than 256 after the letter C. The default value is zero.
+For example, this pattern has two callout points:
+.sp
+  (?C1)abc(?C2)def
+.sp
+If the PCRE_AUTO_CALLOUT option bit is set when a pattern is compiled, PCRE
+automatically inserts callouts, all with number 255, before each item in the
+pattern. For example, if PCRE_AUTO_CALLOUT is used with the pattern
+.sp
+  A(\ed{2}|--)
+.sp
+it is processed as if it were
+.sp
+(?C255)A(?C255)((?C255)\ed{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255)
+.sp
+Notice that there is a callout before and after each parenthesis and
+alternation bar. If the pattern contains a conditional group whose condition is
+an assertion, an automatic callout is inserted immediately before the
+condition. Such a callout may also be inserted explicitly, for example:
+.sp
+  (?(?C9)(?=a)ab|de)
+.sp
+This applies only to assertion conditions (because they are themselves
+independent groups).
+.P
+Automatic callouts can be used for tracking the progress of pattern matching.
+The
+.\" HREF
+\fBpcretest\fP
+.\"
+program has a pattern qualifier (/C) that sets automatic callouts; when it is
+used, the output indicates how the pattern is being matched. This is useful
+information when you are trying to optimize the performance of a particular
+pattern.
+.
+.
+.SH "MISSING CALLOUTS"
+.rs
+.sp
+You should be aware that, because of optimizations in the way PCRE compiles and
+matches patterns, callouts sometimes do not happen exactly as you might expect.
+.P
+At compile time, PCRE "auto-possessifies" repeated items when it knows that
+what follows cannot be part of the repeat. For example, a+[bc] is compiled as
+if it were a++[bc]. The \fBpcretest\fP output when this pattern is anchored and
+then applied with automatic callouts to the string "aaaa" is:
+.sp
+  --->aaaa
+   +0 ^        ^
+   +1 ^        a+
+   +3 ^   ^    [bc]
+  No match
+.sp
+This indicates that when matching [bc] fails, there is no backtracking into a+
+and therefore the callouts that would be taken for the backtracks do not occur.
+You can disable the auto-possessify feature by passing PCRE_NO_AUTO_POSSESS
+to \fBpcre_compile()\fP, or starting the pattern with (*NO_AUTO_POSSESS). If
+this is done in \fBpcretest\fP (using the /O qualifier), the output changes to
+this:
+.sp
+  --->aaaa
+   +0 ^        ^
+   +1 ^        a+
+   +3 ^   ^    [bc]
+   +3 ^  ^     [bc]
+   +3 ^ ^      [bc]
+   +3 ^^       [bc]
+  No match
+.sp
+This time, when matching [bc] fails, the matcher backtracks into a+ and tries
+again, repeatedly, until a+ itself fails.
+.P
+Other optimizations that provide fast "no match" results also affect callouts.
+For example, if the pattern is
+.sp
+  ab(?C4)cd
+.sp
+PCRE knows that any matching string must contain the letter "d". If the subject
+string is "abyz", the lack of "d" means that matching doesn't ever start, and
+the callout is never reached. However, with "abyd", though the result is still
+no match, the callout is obeyed.
+.P
+If the pattern is studied, PCRE knows the minimum length of a matching string,
+and will immediately give a "no match" return without actually running a match
+if the subject is not long enough, or, for unanchored patterns, if it has
+been scanned far enough.
+.P
+You can disable these optimizations by passing the PCRE_NO_START_OPTIMIZE
+option to the matching function, or by starting the pattern with
+(*NO_START_OPT). This slows down the matching process, but does ensure that
+callouts such as the example above are obeyed.
+.
+.
+.SH "THE CALLOUT INTERFACE"
+.rs
+.sp
+During matching, when PCRE reaches a callout point, the external function
+defined by \fIpcre_callout\fP or \fIpcre[16|32]_callout\fP is called (if it is
+set). This applies to both normal and DFA matching. The only argument to the
+callout function is a pointer to a \fBpcre_callout\fP or
+\fBpcre[16|32]_callout\fP block. These structures contains the following
+fields:
+.sp
+  int           \fIversion\fP;
+  int           \fIcallout_number\fP;
+  int          *\fIoffset_vector\fP;
+  const char   *\fIsubject\fP;           (8-bit version)
+  PCRE_SPTR16   \fIsubject\fP;           (16-bit version)
+  PCRE_SPTR32   \fIsubject\fP;           (32-bit version)
+  int           \fIsubject_length\fP;
+  int           \fIstart_match\fP;
+  int           \fIcurrent_position\fP;
+  int           \fIcapture_top\fP;
+  int           \fIcapture_last\fP;
+  void         *\fIcallout_data\fP;
+  int           \fIpattern_position\fP;
+  int           \fInext_item_length\fP;
+  const unsigned char *\fImark\fP;       (8-bit version)
+  const PCRE_UCHAR16  *\fImark\fP;       (16-bit version)
+  const PCRE_UCHAR32  *\fImark\fP;       (32-bit version)
+.sp
+The \fIversion\fP field is an integer containing the version number of the
+block format. The initial version was 0; the current version is 2. The version
+number will change again in future if additional fields are added, but the
+intention is never to remove any of the existing fields.
+.P
+The \fIcallout_number\fP field contains the number of the callout, as compiled
+into the pattern (that is, the number after ?C for manual callouts, and 255 for
+automatically generated callouts).
+.P
+The \fIoffset_vector\fP field is a pointer to the vector of offsets that was
+passed by the caller to the matching function. When \fBpcre_exec()\fP or
+\fBpcre[16|32]_exec()\fP is used, the contents can be inspected, in order to
+extract substrings that have been matched so far, in the same way as for
+extracting substrings after a match has completed. For the DFA matching
+functions, this field is not useful.
+.P
+The \fIsubject\fP and \fIsubject_length\fP fields contain copies of the values
+that were passed to the matching function.
+.P
+The \fIstart_match\fP field normally contains the offset within the subject at
+which the current match attempt started. However, if the escape sequence \eK
+has been encountered, this value is changed to reflect the modified starting
+point. If the pattern is not anchored, the callout function may be called
+several times from the same point in the pattern for different starting points
+in the subject.
+.P
+The \fIcurrent_position\fP field contains the offset within the subject of the
+current match pointer.
+.P
+When the \fBpcre_exec()\fP or \fBpcre[16|32]_exec()\fP is used, the
+\fIcapture_top\fP field contains one more than the number of the highest
+numbered captured substring so far. If no substrings have been captured, the
+value of \fIcapture_top\fP is one. This is always the case when the DFA
+functions are used, because they do not support captured substrings.
+.P
+The \fIcapture_last\fP field contains the number of the most recently captured
+substring. However, when a recursion exits, the value reverts to what it was
+outside the recursion, as do the values of all captured substrings. If no
+substrings have been captured, the value of \fIcapture_last\fP is -1. This is
+always the case for the DFA matching functions.
+.P
+The \fIcallout_data\fP field contains a value that is passed to a matching
+function specifically so that it can be passed back in callouts. It is passed
+in the \fIcallout_data\fP field of a \fBpcre_extra\fP or \fBpcre[16|32]_extra\fP
+data structure. If no such data was passed, the value of \fIcallout_data\fP in
+a callout block is NULL. There is a description of the \fBpcre_extra\fP
+structure in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation.
+.P
+The \fIpattern_position\fP field is present from version 1 of the callout
+structure. It contains the offset to the next item to be matched in the pattern
+string.
+.P
+The \fInext_item_length\fP field is present from version 1 of the callout
+structure. It contains the length of the next item to be matched in the pattern
+string. When the callout immediately precedes an alternation bar, a closing
+parenthesis, or the end of the pattern, the length is zero. When the callout
+precedes an opening parenthesis, the length is that of the entire subpattern.
+.P
+The \fIpattern_position\fP and \fInext_item_length\fP fields are intended to
+help in distinguishing between different automatic callouts, which all have the
+same callout number. However, they are set for all callouts.
+.P
+The \fImark\fP field is present from version 2 of the callout structure. In
+callouts from \fBpcre_exec()\fP or \fBpcre[16|32]_exec()\fP it contains a
+pointer to the zero-terminated name of the most recently passed (*MARK),
+(*PRUNE), or (*THEN) item in the match, or NULL if no such items have been
+passed. Instances of (*PRUNE) or (*THEN) without a name do not obliterate a
+previous (*MARK). In callouts from the DFA matching functions this field always
+contains NULL.
+.
+.
+.SH "RETURN VALUES"
+.rs
+.sp
+The external callout function returns an integer to PCRE. If the value is zero,
+matching proceeds as normal. If the value is greater than zero, matching fails
+at the current point, but the testing of other matching possibilities goes
+ahead, just as if a lookahead assertion had failed. If the value is less than
+zero, the match is abandoned, the matching function returns the negative value.
+.P
+Negative values should normally be chosen from the set of PCRE_ERROR_xxx
+values. In particular, PCRE_ERROR_NOMATCH forces a standard "no match" failure.
+The error number PCRE_ERROR_CALLOUT is reserved for use by callout functions;
+it will never be used by PCRE itself.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 12 November 2013
+Copyright (c) 1997-2013 University of Cambridge.
+.fi
diff --git a/doc/pcrecompat.3 b/doc/pcrecompat.3
new file mode 100644
index 0000000..0cc4019
--- /dev/null
+++ b/doc/pcrecompat.3
@@ -0,0 +1,200 @@
+.TH PCRECOMPAT 3 "10 November 2013" "PCRE 8.34"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "DIFFERENCES BETWEEN PCRE AND PERL"
+.rs
+.sp
+This document describes the differences in the ways that PCRE and Perl handle
+regular expressions. The differences described here are with respect to Perl
+versions 5.10 and above.
+.P
+1. PCRE has only a subset of Perl's Unicode support. Details of what it does
+have are given in the
+.\" HREF
+\fBpcreunicode\fP
+.\"
+page.
+.P
+2. PCRE allows repeat quantifiers only on parenthesized assertions, but they do
+not mean what you might think. For example, (?!a){3} does not assert that the
+next three characters are not "a". It just asserts that the next character is
+not "a" three times (in principle: PCRE optimizes this to run the assertion
+just once). Perl allows repeat quantifiers on other assertions such as \eb, but
+these do not seem to have any use.
+.P
+3. Capturing subpatterns that occur inside negative lookahead assertions are
+counted, but their entries in the offsets vector are never set. Perl sometimes
+(but not always) sets its numerical variables from inside negative assertions.
+.P
+4. Though binary zero characters are supported in the subject string, they are
+not allowed in a pattern string because it is passed as a normal C string,
+terminated by zero. The escape sequence \e0 can be used in the pattern to
+represent a binary zero.
+.P
+5. The following Perl escape sequences are not supported: \el, \eu, \eL,
+\eU, and \eN when followed by a character name or Unicode value. (\eN on its
+own, matching a non-newline character, is supported.) In fact these are
+implemented by Perl's general string-handling and are not part of its pattern
+matching engine. If any of these are encountered by PCRE, an error is
+generated by default. However, if the PCRE_JAVASCRIPT_COMPAT option is set,
+\eU and \eu are interpreted as JavaScript interprets them.
+.P
+6. The Perl escape sequences \ep, \eP, and \eX are supported only if PCRE is
+built with Unicode character property support. The properties that can be
+tested with \ep and \eP are limited to the general category properties such as
+Lu and Nd, script names such as Greek or Han, and the derived properties Any
+and L&. PCRE does support the Cs (surrogate) property, which Perl does not; the
+Perl documentation says "Because Perl hides the need for the user to understand
+the internal representation of Unicode characters, there is no need to
+implement the somewhat messy concept of surrogates."
+.P
+7. PCRE does support the \eQ...\eE escape for quoting substrings. Characters in
+between are treated as literals. This is slightly different from Perl in that $
+and @ are also handled as literals inside the quotes. In Perl, they cause
+variable interpolation (but of course PCRE does not have variables). Note the
+following examples:
+.sp
+    Pattern            PCRE matches      Perl matches
+.sp
+.\" JOIN
+    \eQabc$xyz\eE        abc$xyz           abc followed by the
+                                           contents of $xyz
+    \eQabc\e$xyz\eE       abc\e$xyz          abc\e$xyz
+    \eQabc\eE\e$\eQxyz\eE   abc$xyz           abc$xyz
+.sp
+The \eQ...\eE sequence is recognized both inside and outside character classes.
+.P
+8. Fairly obviously, PCRE does not support the (?{code}) and (??{code})
+constructions. However, there is support for recursive patterns. This is not
+available in Perl 5.8, but it is in Perl 5.10. Also, the PCRE "callout"
+feature allows an external function to be called during pattern matching. See
+the
+.\" HREF
+\fBpcrecallout\fP
+.\"
+documentation for details.
+.P
+9. Subpatterns that are called as subroutines (whether or not recursively) are
+always treated as atomic groups in PCRE. This is like Python, but unlike Perl.
+Captured values that are set outside a subroutine call can be reference from
+inside in PCRE, but not in Perl. There is a discussion that explains these
+differences in more detail in the
+.\" HTML 
+.\" 
+section on recursion differences from Perl
+.\"
+in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+page.
+.P
+10. If any of the backtracking control verbs are used in a subpattern that is
+called as a subroutine (whether or not recursively), their effect is confined
+to that subpattern; it does not extend to the surrounding pattern. This is not
+always the case in Perl. In particular, if (*THEN) is present in a group that
+is called as a subroutine, its action is limited to that group, even if the
+group does not contain any | characters. Note that such subpatterns are
+processed as anchored at the point where they are tested.
+.P
+11. If a pattern contains more than one backtracking control verb, the first
+one that is backtracked onto acts. For example, in the pattern
+A(*COMMIT)B(*PRUNE)C a failure in B triggers (*COMMIT), but a failure in C
+triggers (*PRUNE). Perl's behaviour is more complex; in many cases it is the
+same as PCRE, but there are examples where it differs.
+.P
+12. Most backtracking verbs in assertions have their normal actions. They are
+not confined to the assertion.
+.P
+13. There are some differences that are concerned with the settings of captured
+strings when part of a pattern is repeated. For example, matching "aba" against
+the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b".
+.P
+14. PCRE's handling of duplicate subpattern numbers and duplicate subpattern
+names is not as general as Perl's. This is a consequence of the fact the PCRE
+works internally just with numbers, using an external table to translate
+between numbers and names. In particular, a pattern such as (?|(?A)|(?
+.
+.SH DESCRIPTION
+.rs
+.sp
+The C++ wrapper for PCRE was provided by Google Inc. Some additional
+functionality was added by Giuseppe Maxia. This brief man page was constructed
+from the notes in the \fIpcrecpp.h\fP file, which should be consulted for
+further details. Note that the C++ wrapper supports only the original 8-bit
+PCRE library. There is no 16-bit or 32-bit support at present.
+.
+.
+.SH "MATCHING INTERFACE"
+.rs
+.sp
+The "FullMatch" operation checks that supplied text matches a supplied pattern
+exactly. If pointer arguments are supplied, it copies matched sub-strings that
+match sub-patterns into them.
+.sp
+  Example: successful match
+     pcrecpp::RE re("h.*o");
+     re.FullMatch("hello");
+.sp
+  Example: unsuccessful match (requires full match):
+     pcrecpp::RE re("e");
+     !re.FullMatch("hello");
+.sp
+  Example: creating a temporary RE object:
+     pcrecpp::RE("h.*o").FullMatch("hello");
+.sp
+You can pass in a "const char*" or a "string" for "text". The examples below
+tend to use a const char*. You can, as in the different examples above, store
+the RE object explicitly in a variable or use a temporary RE object. The
+examples below use one mode or the other arbitrarily. Either could correctly be
+used for any of these examples.
+.P
+You must supply extra pointer arguments to extract matched subpieces.
+.sp
+  Example: extracts "ruby" into "s" and 1234 into "i"
+     int i;
+     string s;
+     pcrecpp::RE re("(\e\ew+):(\e\ed+)");
+     re.FullMatch("ruby:1234", &s, &i);
+.sp
+  Example: does not try to extract any extra sub-patterns
+     re.FullMatch("ruby:1234", &s);
+.sp
+  Example: does not try to extract into NULL
+     re.FullMatch("ruby:1234", NULL, &i);
+.sp
+  Example: integer overflow causes failure
+     !re.FullMatch("ruby:1234567891234", NULL, &i);
+.sp
+  Example: fails because there aren't enough sub-patterns:
+     !pcrecpp::RE("\e\ew+:\e\ed+").FullMatch("ruby:1234", &s);
+.sp
+  Example: fails because string cannot be stored in integer
+     !pcrecpp::RE("(.*)").FullMatch("ruby", &i);
+.sp
+The provided pointer arguments can be pointers to any scalar numeric
+type, or one of:
+.sp
+   string        (matched piece is copied to string)
+   StringPiece   (StringPiece is mutated to point to matched piece)
+   T             (where "bool T::ParseFrom(const char*, int)" exists)
+   NULL          (the corresponding matched sub-pattern is not copied)
+.sp
+The function returns true iff all of the following conditions are satisfied:
+.sp
+  a. "text" matches "pattern" exactly;
+.sp
+  b. The number of matched sub-patterns is >= number of supplied
+     pointers;
+.sp
+  c. The "i"th argument has a suitable type for holding the
+     string captured as the "i"th sub-pattern. If you pass in
+     void * NULL for the "i"th argument, or a non-void * NULL
+     of the correct type, or pass fewer arguments than the
+     number of sub-patterns, "i"th captured sub-pattern is
+     ignored.
+.sp
+CAVEAT: An optional sub-pattern that does not exist in the matched
+string is assigned the empty string. Therefore, the following will
+return false (because the empty string is not a valid number):
+.sp
+   int number;
+   pcrecpp::RE::FullMatch("abc", "[a-z]+(\e\ed+)?", &number);
+.sp
+The matching interface supports at most 16 arguments per call.
+If you need more, consider using the more general interface
+\fBpcrecpp::RE::DoMatch\fP. See \fBpcrecpp.h\fP for the signature for
+\fBDoMatch\fP.
+.P
+NOTE: Do not use \fBno_arg\fP, which is used internally to mark the end of a
+list of optional arguments, as a placeholder for missing arguments, as this can
+lead to segfaults.
+.
+.
+.SH "QUOTING METACHARACTERS"
+.rs
+.sp
+You can use the "QuoteMeta" operation to insert backslashes before all
+potentially meaningful characters in a string. The returned string, used as a
+regular expression, will exactly match the original string.
+.sp
+  Example:
+     string quoted = RE::QuoteMeta(unquoted);
+.sp
+Note that it's legal to escape a character even if it has no special meaning in
+a regular expression -- so this function does that. (This also makes it
+identical to the perl function of the same name; see "perldoc -f quotemeta".)
+For example, "1.5-2.0?" becomes "1\e.5\e-2\e.0\e?".
+.
+.SH "PARTIAL MATCHES"
+.rs
+.sp
+You can use the "PartialMatch" operation when you want the pattern
+to match any substring of the text.
+.sp
+  Example: simple search for a string:
+     pcrecpp::RE("ell").PartialMatch("hello");
+.sp
+  Example: find first number in a string:
+     int number;
+     pcrecpp::RE re("(\e\ed+)");
+     re.PartialMatch("x*100 + 20", &number);
+     assert(number == 100);
+.
+.
+.SH "UTF-8 AND THE MATCHING INTERFACE"
+.rs
+.sp
+By default, pattern and text are plain text, one byte per character. The UTF8
+flag, passed to the constructor, causes both pattern and string to be treated
+as UTF-8 text, still a byte stream but potentially multiple bytes per
+character. In practice, the text is likelier to be UTF-8 than the pattern, but
+the match returned may depend on the UTF8 flag, so always use it when matching
+UTF8 text. For example, "." will match one byte normally but with UTF8 set may
+match up to three bytes of a multi-byte character.
+.sp
+  Example:
+     pcrecpp::RE_Options options;
+     options.set_utf8();
+     pcrecpp::RE re(utf8_pattern, options);
+     re.FullMatch(utf8_string);
+.sp
+  Example: using the convenience function UTF8():
+     pcrecpp::RE re(utf8_pattern, pcrecpp::UTF8());
+     re.FullMatch(utf8_string);
+.sp
+NOTE: The UTF8 flag is ignored if pcre was not configured with the
+      --enable-utf8 flag.
+.
+.
+.SH "PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE"
+.rs
+.sp
+PCRE defines some modifiers to change the behavior of the regular expression
+engine. The C++ wrapper defines an auxiliary class, RE_Options, as a vehicle to
+pass such modifiers to a RE class. Currently, the following modifiers are
+supported:
+.sp
+   modifier              description               Perl corresponding
+.sp
+   PCRE_CASELESS         case insensitive match      /i
+   PCRE_MULTILINE        multiple lines match        /m
+   PCRE_DOTALL           dot matches newlines        /s
+   PCRE_DOLLAR_ENDONLY   $ matches only at end       N/A
+   PCRE_EXTRA            strict escape parsing       N/A
+   PCRE_EXTENDED         ignore white spaces         /x
+   PCRE_UTF8             handles UTF8 chars          built-in
+   PCRE_UNGREEDY         reverses * and *?           N/A
+   PCRE_NO_AUTO_CAPTURE  disables capturing parens   N/A (*)
+.sp
+(*) Both Perl and PCRE allow non capturing parentheses by means of the
+"?:" modifier within the pattern itself. e.g. (?:ab|cd) does not
+capture, while (ab|cd) does.
+.P
+For a full account on how each modifier works, please check the
+PCRE API reference page.
+.P
+For each modifier, there are two member functions whose name is made
+out of the modifier in lowercase, without the "PCRE_" prefix. For
+instance, PCRE_CASELESS is handled by
+.sp
+  bool caseless()
+.sp
+which returns true if the modifier is set, and
+.sp
+  RE_Options & set_caseless(bool)
+.sp
+which sets or unsets the modifier. Moreover, PCRE_EXTRA_MATCH_LIMIT can be
+accessed through the \fBset_match_limit()\fP and \fBmatch_limit()\fP member
+functions. Setting \fImatch_limit\fP to a non-zero value will limit the
+execution of pcre to keep it from doing bad things like blowing the stack or
+taking an eternity to return a result. A value of 5000 is good enough to stop
+stack blowup in a 2MB thread stack. Setting \fImatch_limit\fP to zero disables
+match limiting. Alternatively, you can call \fBmatch_limit_recursion()\fP
+which uses PCRE_EXTRA_MATCH_LIMIT_RECURSION to limit how much PCRE
+recurses. \fBmatch_limit()\fP limits the number of matches PCRE does;
+\fBmatch_limit_recursion()\fP limits the depth of internal recursion, and
+therefore the amount of stack that is used.
+.P
+Normally, to pass one or more modifiers to a RE class, you declare
+a \fIRE_Options\fP object, set the appropriate options, and pass this
+object to a RE constructor. Example:
+.sp
+   RE_Options opt;
+   opt.set_caseless(true);
+   if (RE("HELLO", opt).PartialMatch("hello world")) ...
+.sp
+RE_options has two constructors. The default constructor takes no arguments and
+creates a set of flags that are off by default. The optional parameter
+\fIoption_flags\fP is to facilitate transfer of legacy code from C programs.
+This lets you do
+.sp
+   RE(pattern,
+     RE_Options(PCRE_CASELESS|PCRE_MULTILINE)).PartialMatch(str);
+.sp
+However, new code is better off doing
+.sp
+   RE(pattern,
+     RE_Options().set_caseless(true).set_multiline(true))
+       .PartialMatch(str);
+.sp
+If you are going to pass one of the most used modifiers, there are some
+convenience functions that return a RE_Options class with the
+appropriate modifier already set: \fBCASELESS()\fP, \fBUTF8()\fP,
+\fBMULTILINE()\fP, \fBDOTALL\fP(), and \fBEXTENDED()\fP.
+.P
+If you need to set several options at once, and you don't want to go through
+the pains of declaring a RE_Options object and setting several options, there
+is a parallel method that give you such ability on the fly. You can concatenate
+several \fBset_xxxxx()\fP member functions, since each of them returns a
+reference to its class object. For example, to pass PCRE_CASELESS,
+PCRE_EXTENDED, and PCRE_MULTILINE to a RE with one statement, you may write:
+.sp
+   RE(" ^ xyz \e\es+ .* blah$",
+     RE_Options()
+       .set_caseless(true)
+       .set_extended(true)
+       .set_multiline(true)).PartialMatch(sometext);
+.sp
+.
+.
+.SH "SCANNING TEXT INCREMENTALLY"
+.rs
+.sp
+The "Consume" operation may be useful if you want to repeatedly
+match regular expressions at the front of a string and skip over
+them as they match. This requires use of the "StringPiece" type,
+which represents a sub-range of a real string. Like RE, StringPiece
+is defined in the pcrecpp namespace.
+.sp
+  Example: read lines of the form "var = value" from a string.
+     string contents = ...;                 // Fill string somehow
+     pcrecpp::StringPiece input(contents);  // Wrap in a StringPiece
+.sp
+     string var;
+     int value;
+     pcrecpp::RE re("(\e\ew+) = (\e\ed+)\en");
+     while (re.Consume(&input, &var, &value)) {
+       ...;
+     }
+.sp
+Each successful call to "Consume" will set "var/value", and also
+advance "input" so it points past the matched text.
+.P
+The "FindAndConsume" operation is similar to "Consume" but does not
+anchor your match at the beginning of the string. For example, you
+could extract all words from a string by repeatedly calling
+.sp
+  pcrecpp::RE("(\e\ew+)").FindAndConsume(&input, &word)
+.
+.
+.SH "PARSING HEX/OCTAL/C-RADIX NUMBERS"
+.rs
+.sp
+By default, if you pass a pointer to a numeric value, the
+corresponding text is interpreted as a base-10 number. You can
+instead wrap the pointer with a call to one of the operators Hex(),
+Octal(), or CRadix() to interpret the text in another base. The
+CRadix operator interprets C-style "0" (base-8) and "0x" (base-16)
+prefixes, but defaults to base-10.
+.sp
+  Example:
+    int a, b, c, d;
+    pcrecpp::RE re("(.*) (.*) (.*) (.*)");
+    re.FullMatch("100 40 0100 0x40",
+                 pcrecpp::Octal(&a), pcrecpp::Hex(&b),
+                 pcrecpp::CRadix(&c), pcrecpp::CRadix(&d));
+.sp
+will leave 64 in a, b, c, and d.
+.
+.
+.SH "REPLACING PARTS OF STRINGS"
+.rs
+.sp
+You can replace the first match of "pattern" in "str" with "rewrite".
+Within "rewrite", backslash-escaped digits (\e1 to \e9) can be
+used to insert text matching corresponding parenthesized group
+from the pattern. \e0 in "rewrite" refers to the entire matching
+text. For example:
+.sp
+  string s = "yabba dabba doo";
+  pcrecpp::RE("b+").Replace("d", &s);
+.sp
+will leave "s" containing "yada dabba doo". The result is true if the pattern
+matches and a replacement occurs, false otherwise.
+.P
+\fBGlobalReplace\fP is like \fBReplace\fP except that it replaces all
+occurrences of the pattern in the string with the rewrite. Replacements are
+not subject to re-matching. For example:
+.sp
+  string s = "yabba dabba doo";
+  pcrecpp::RE("b+").GlobalReplace("d", &s);
+.sp
+will leave "s" containing "yada dada doo". It returns the number of
+replacements made.
+.P
+\fBExtract\fP is like \fBReplace\fP, except that if the pattern matches,
+"rewrite" is copied into "out" (an additional argument) with substitutions.
+The non-matching portions of "text" are ignored. Returns true iff a match
+occurred and the extraction happened successfully;  if no match occurs, the
+string is left unaffected.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+The C++ wrapper was contributed by Google Inc.
+Copyright (c) 2007 Google Inc.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 08 January 2012
+.fi
diff --git a/doc/pcredemo.3 b/doc/pcredemo.3
new file mode 100644
index 0000000..194629b
--- /dev/null
+++ b/doc/pcredemo.3
@@ -0,0 +1,424 @@
+.\" Start example.
+.de EX
+.  nr mE \\n(.f
+.  nf
+.  nh
+.  ft CW
+..
+.
+.
+.\" End example.
+.de EE
+.  ft \\n(mE
+.  fi
+.  hy \\n(HY
+..
+.
+.EX
+/*************************************************
+*           PCRE DEMONSTRATION PROGRAM           *
+*************************************************/
+
+/* This is a demonstration program to illustrate the most straightforward ways
+of calling the PCRE regular expression library from a C program. See the
+pcresample documentation for a short discussion ("man pcresample" if you have
+the PCRE man pages installed).
+
+In Unix-like environments, if PCRE is installed in your standard system
+libraries, you should be able to compile this program using this command:
+
+gcc -Wall pcredemo.c -lpcre -o pcredemo
+
+If PCRE is not installed in a standard place, it is likely to be installed with
+support for the pkg-config mechanism. If you have pkg-config, you can compile
+this program using this command:
+
+gcc -Wall pcredemo.c `pkg-config --cflags --libs libpcre` -o pcredemo
+
+If you do not have pkg-config, you may have to use this:
+
+gcc -Wall pcredemo.c -I/usr/local/include -L/usr/local/lib \e
+  -R/usr/local/lib -lpcre -o pcredemo
+
+Replace "/usr/local/include" and "/usr/local/lib" with wherever the include and
+library files for PCRE are installed on your system. Only some operating
+systems (e.g. Solaris) use the -R option.
+
+Building under Windows:
+
+If you want to statically link this program against a non-dll .a file, you must
+define PCRE_STATIC before including pcre.h, otherwise the pcre_malloc() and
+pcre_free() exported functions will be declared __declspec(dllimport), with
+unwanted results. So in this environment, uncomment the following line. */
+
+/* #define PCRE_STATIC */
+
+#include 
+#include 
+#include 
+
+#define OVECCOUNT 30    /* should be a multiple of 3 */
+
+
+int main(int argc, char **argv)
+{
+pcre *re;
+const char *error;
+char *pattern;
+char *subject;
+unsigned char *name_table;
+unsigned int option_bits;
+int erroffset;
+int find_all;
+int crlf_is_newline;
+int namecount;
+int name_entry_size;
+int ovector[OVECCOUNT];
+int subject_length;
+int rc, i;
+int utf8;
+
+
+/**************************************************************************
+* First, sort out the command line. There is only one possible option at  *
+* the moment, "-g" to request repeated matching to find all occurrences,  *
+* like Perl's /g option. We set the variable find_all to a non-zero value *
+* if the -g option is present. Apart from that, there must be exactly two *
+* arguments.                                                              *
+**************************************************************************/
+
+find_all = 0;
+for (i = 1; i < argc; i++)
+  {
+  if (strcmp(argv[i], "-g") == 0) find_all = 1;
+    else break;
+  }
+
+/* After the options, we require exactly two arguments, which are the pattern,
+and the subject string. */
+
+if (argc - i != 2)
+  {
+  printf("Two arguments required: a regex and a subject string\en");
+  return 1;
+  }
+
+pattern = argv[i];
+subject = argv[i+1];
+subject_length = (int)strlen(subject);
+
+
+/*************************************************************************
+* Now we are going to compile the regular expression pattern, and handle *
+* and errors that are detected.                                          *
+*************************************************************************/
+
+re = pcre_compile(
+  pattern,              /* the pattern */
+  0,                    /* default options */
+  &error,               /* for error message */
+  &erroffset,           /* for error offset */
+  NULL);                /* use default character tables */
+
+/* Compilation failed: print the error message and exit */
+
+if (re == NULL)
+  {
+  printf("PCRE compilation failed at offset %d: %s\en", erroffset, error);
+  return 1;
+  }
+
+
+/*************************************************************************
+* If the compilation succeeded, we call PCRE again, in order to do a     *
+* pattern match against the subject string. This does just ONE match. If *
+* further matching is needed, it will be done below.                     *
+*************************************************************************/
+
+rc = pcre_exec(
+  re,                   /* the compiled pattern */
+  NULL,                 /* no extra data - we didn't study the pattern */
+  subject,              /* the subject string */
+  subject_length,       /* the length of the subject */
+  0,                    /* start at offset 0 in the subject */
+  0,                    /* default options */
+  ovector,              /* output vector for substring information */
+  OVECCOUNT);           /* number of elements in the output vector */
+
+/* Matching failed: handle error cases */
+
+if (rc < 0)
+  {
+  switch(rc)
+    {
+    case PCRE_ERROR_NOMATCH: printf("No match\en"); break;
+    /*
+    Handle other special cases if you like
+    */
+    default: printf("Matching error %d\en", rc); break;
+    }
+  pcre_free(re);     /* Release memory used for the compiled pattern */
+  return 1;
+  }
+
+/* Match succeded */
+
+printf("\enMatch succeeded at offset %d\en", ovector[0]);
+
+
+/*************************************************************************
+* We have found the first match within the subject string. If the output *
+* vector wasn't big enough, say so. Then output any substrings that were *
+* captured.                                                              *
+*************************************************************************/
+
+/* The output vector wasn't big enough */
+
+if (rc == 0)
+  {
+  rc = OVECCOUNT/3;
+  printf("ovector only has room for %d captured substrings\en", rc - 1);
+  }
+
+/* Show substrings stored in the output vector by number. Obviously, in a real
+application you might want to do things other than print them. */
+
+for (i = 0; i < rc; i++)
+  {
+  char *substring_start = subject + ovector[2*i];
+  int substring_length = ovector[2*i+1] - ovector[2*i];
+  printf("%2d: %.*s\en", i, substring_length, substring_start);
+  }
+
+
+/**************************************************************************
+* That concludes the basic part of this demonstration program. We have    *
+* compiled a pattern, and performed a single match. The code that follows *
+* shows first how to access named substrings, and then how to code for    *
+* repeated matches on the same subject.                                   *
+**************************************************************************/
+
+/* See if there are any named substrings, and if so, show them by name. First
+we have to extract the count of named parentheses from the pattern. */
+
+(void)pcre_fullinfo(
+  re,                   /* the compiled pattern */
+  NULL,                 /* no extra data - we didn't study the pattern */
+  PCRE_INFO_NAMECOUNT,  /* number of named substrings */
+  &namecount);          /* where to put the answer */
+
+if (namecount <= 0) printf("No named substrings\en"); else
+  {
+  unsigned char *tabptr;
+  printf("Named substrings\en");
+
+  /* Before we can access the substrings, we must extract the table for
+  translating names to numbers, and the size of each entry in the table. */
+
+  (void)pcre_fullinfo(
+    re,                       /* the compiled pattern */
+    NULL,                     /* no extra data - we didn't study the pattern */
+    PCRE_INFO_NAMETABLE,      /* address of the table */
+    &name_table);             /* where to put the answer */
+
+  (void)pcre_fullinfo(
+    re,                       /* the compiled pattern */
+    NULL,                     /* no extra data - we didn't study the pattern */
+    PCRE_INFO_NAMEENTRYSIZE,  /* size of each entry in the table */
+    &name_entry_size);        /* where to put the answer */
+
+  /* Now we can scan the table and, for each entry, print the number, the name,
+  and the substring itself. */
+
+  tabptr = name_table;
+  for (i = 0; i < namecount; i++)
+    {
+    int n = (tabptr[0] << 8) | tabptr[1];
+    printf("(%d) %*s: %.*s\en", n, name_entry_size - 3, tabptr + 2,
+      ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]);
+    tabptr += name_entry_size;
+    }
+  }
+
+
+/*************************************************************************
+* If the "-g" option was given on the command line, we want to continue  *
+* to search for additional matches in the subject string, in a similar   *
+* way to the /g option in Perl. This turns out to be trickier than you   *
+* might think because of the possibility of matching an empty string.    *
+* What happens is as follows:                                            *
+*                                                                        *
+* If the previous match was NOT for an empty string, we can just start   *
+* the next match at the end of the previous one.                         *
+*                                                                        *
+* If the previous match WAS for an empty string, we can't do that, as it *
+* would lead to an infinite loop. Instead, a special call of pcre_exec() *
+* is made with the PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED flags set.    *
+* The first of these tells PCRE that an empty string at the start of the *
+* subject is not a valid match; other possibilities must be tried. The   *
+* second flag restricts PCRE to one match attempt at the initial string  *
+* position. If this match succeeds, an alternative to the empty string   *
+* match has been found, and we can print it and proceed round the loop,  *
+* advancing by the length of whatever was found. If this match does not  *
+* succeed, we still stay in the loop, advancing by just one character.   *
+* In UTF-8 mode, which can be set by (*UTF8) in the pattern, this may be *
+* more than one byte.                                                    *
+*                                                                        *
+* However, there is a complication concerned with newlines. When the     *
+* newline convention is such that CRLF is a valid newline, we must       *
+* advance by two characters rather than one. The newline convention can  *
+* be set in the regex by (*CR), etc.; if not, we must find the default.  *
+*************************************************************************/
+
+if (!find_all)     /* Check for -g */
+  {
+  pcre_free(re);   /* Release the memory used for the compiled pattern */
+  return 0;        /* Finish unless -g was given */
+  }
+
+/* Before running the loop, check for UTF-8 and whether CRLF is a valid newline
+sequence. First, find the options with which the regex was compiled; extract
+the UTF-8 state, and mask off all but the newline options. */
+
+(void)pcre_fullinfo(re, NULL, PCRE_INFO_OPTIONS, &option_bits);
+utf8 = option_bits & PCRE_UTF8;
+option_bits &= PCRE_NEWLINE_CR|PCRE_NEWLINE_LF|PCRE_NEWLINE_CRLF|
+               PCRE_NEWLINE_ANY|PCRE_NEWLINE_ANYCRLF;
+
+/* If no newline options were set, find the default newline convention from the
+build configuration. */
+
+if (option_bits == 0)
+  {
+  int d;
+  (void)pcre_config(PCRE_CONFIG_NEWLINE, &d);
+  /* Note that these values are always the ASCII ones, even in
+  EBCDIC environments. CR = 13, NL = 10. */
+  option_bits = (d == 13)? PCRE_NEWLINE_CR :
+          (d == 10)? PCRE_NEWLINE_LF :
+          (d == (13<<8 | 10))? PCRE_NEWLINE_CRLF :
+          (d == -2)? PCRE_NEWLINE_ANYCRLF :
+          (d == -1)? PCRE_NEWLINE_ANY : 0;
+  }
+
+/* See if CRLF is a valid newline sequence. */
+
+crlf_is_newline =
+     option_bits == PCRE_NEWLINE_ANY ||
+     option_bits == PCRE_NEWLINE_CRLF ||
+     option_bits == PCRE_NEWLINE_ANYCRLF;
+
+/* Loop for second and subsequent matches */
+
+for (;;)
+  {
+  int options = 0;                 /* Normally no options */
+  int start_offset = ovector[1];   /* Start at end of previous match */
+
+  /* If the previous match was for an empty string, we are finished if we are
+  at the end of the subject. Otherwise, arrange to run another match at the
+  same point to see if a non-empty match can be found. */
+
+  if (ovector[0] == ovector[1])
+    {
+    if (ovector[0] == subject_length) break;
+    options = PCRE_NOTEMPTY_ATSTART | PCRE_ANCHORED;
+    }
+
+  /* Run the next matching operation */
+
+  rc = pcre_exec(
+    re,                   /* the compiled pattern */
+    NULL,                 /* no extra data - we didn't study the pattern */
+    subject,              /* the subject string */
+    subject_length,       /* the length of the subject */
+    start_offset,         /* starting offset in the subject */
+    options,              /* options */
+    ovector,              /* output vector for substring information */
+    OVECCOUNT);           /* number of elements in the output vector */
+
+  /* This time, a result of NOMATCH isn't an error. If the value in "options"
+  is zero, it just means we have found all possible matches, so the loop ends.
+  Otherwise, it means we have failed to find a non-empty-string match at a
+  point where there was a previous empty-string match. In this case, we do what
+  Perl does: advance the matching position by one character, and continue. We
+  do this by setting the "end of previous match" offset, because that is picked
+  up at the top of the loop as the point at which to start again.
+
+  There are two complications: (a) When CRLF is a valid newline sequence, and
+  the current position is just before it, advance by an extra byte. (b)
+  Otherwise we must ensure that we skip an entire UTF-8 character if we are in
+  UTF-8 mode. */
+
+  if (rc == PCRE_ERROR_NOMATCH)
+    {
+    if (options == 0) break;                    /* All matches found */
+    ovector[1] = start_offset + 1;              /* Advance one byte */
+    if (crlf_is_newline &&                      /* If CRLF is newline & */
+        start_offset < subject_length - 1 &&    /* we are at CRLF, */
+        subject[start_offset] == '\er' &&
+        subject[start_offset + 1] == '\en')
+      ovector[1] += 1;                          /* Advance by one more. */
+    else if (utf8)                              /* Otherwise, ensure we */
+      {                                         /* advance a whole UTF-8 */
+      while (ovector[1] < subject_length)       /* character. */
+        {
+        if ((subject[ovector[1]] & 0xc0) != 0x80) break;
+        ovector[1] += 1;
+        }
+      }
+    continue;    /* Go round the loop again */
+    }
+
+  /* Other matching errors are not recoverable. */
+
+  if (rc < 0)
+    {
+    printf("Matching error %d\en", rc);
+    pcre_free(re);    /* Release memory used for the compiled pattern */
+    return 1;
+    }
+
+  /* Match succeded */
+
+  printf("\enMatch succeeded again at offset %d\en", ovector[0]);
+
+  /* The match succeeded, but the output vector wasn't big enough. */
+
+  if (rc == 0)
+    {
+    rc = OVECCOUNT/3;
+    printf("ovector only has room for %d captured substrings\en", rc - 1);
+    }
+
+  /* As before, show substrings stored in the output vector by number, and then
+  also any named substrings. */
+
+  for (i = 0; i < rc; i++)
+    {
+    char *substring_start = subject + ovector[2*i];
+    int substring_length = ovector[2*i+1] - ovector[2*i];
+    printf("%2d: %.*s\en", i, substring_length, substring_start);
+    }
+
+  if (namecount <= 0) printf("No named substrings\en"); else
+    {
+    unsigned char *tabptr = name_table;
+    printf("Named substrings\en");
+    for (i = 0; i < namecount; i++)
+      {
+      int n = (tabptr[0] << 8) | tabptr[1];
+      printf("(%d) %*s: %.*s\en", n, name_entry_size - 3, tabptr + 2,
+        ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]);
+      tabptr += name_entry_size;
+      }
+    }
+  }      /* End of loop to find second and subsequent matches */
+
+printf("\en");
+pcre_free(re);       /* Release memory used for the compiled pattern */
+return 0;
+}
+
+/* End of pcredemo.c */
+.EE
diff --git a/doc/pcregrep.1 b/doc/pcregrep.1
new file mode 100644
index 0000000..07b8f57
--- /dev/null
+++ b/doc/pcregrep.1
@@ -0,0 +1,687 @@
+.TH PCREGREP 1 "03 April 2014" "PCRE 8.35"
+.SH NAME
+pcregrep - a grep with Perl-compatible regular expressions.
+.SH SYNOPSIS
+.B pcregrep [options] [long options] [pattern] [path1 path2 ...]
+.B zpcregrep [options] [long options] [pattern] [file1 file2 ...]
+.
+.SH DESCRIPTION
+.rs
+.sp
+\fBpcregrep\fP searches files for character patterns, in the same way as other
+grep commands do, but it uses the PCRE regular expression library to support
+patterns that are compatible with the regular expressions of Perl 5. See
+.\" HREF
+\fBpcresyntax\fP(3)
+.\"
+for a quick-reference summary of pattern syntax, or
+.\" HREF
+\fBpcrepattern\fP(3)
+.\"
+for a full description of the syntax and semantics of the regular expressions
+that PCRE supports.
+.P
+Patterns, whether supplied on the command line or in a separate file, are given
+without delimiters. For example:
+.sp
+  pcregrep Thursday /etc/motd
+.sp
+If you attempt to use delimiters (for example, by surrounding a pattern with
+slashes, as is common in Perl scripts), they are interpreted as part of the
+pattern. Quotes can of course be used to delimit patterns on the command line
+because they are interpreted by the shell, and indeed quotes are required if a
+pattern contains white space or shell metacharacters.
+.P
+The first argument that follows any option settings is treated as the single
+pattern to be matched when neither \fB-e\fP nor \fB-f\fP is present.
+Conversely, when one or both of these options are used to specify patterns, all
+arguments are treated as path names. At least one of \fB-e\fP, \fB-f\fP, or an
+argument pattern must be provided.
+.P
+If no files are specified, \fBpcregrep\fP reads the standard input. The
+standard input can also be referenced by a name consisting of a single hyphen.
+For example:
+.sp
+  pcregrep some-pattern /file1 - /file3
+.sp
+By default, each line that matches a pattern is copied to the standard
+output, and if there is more than one file, the file name is output at the
+start of each line, followed by a colon. However, there are options that can
+change how \fBpcregrep\fP behaves. In particular, the \fB-M\fP option makes it
+possible to search for patterns that span line boundaries. What defines a line
+boundary is controlled by the \fB-N\fP (\fB--newline\fP) option.
+.P
+The amount of memory used for buffering files that are being scanned is
+controlled by a parameter that can be set by the \fB--buffer-size\fP option.
+The default value for this parameter is specified when \fBpcregrep\fP is built,
+with the default default being 20K. A block of memory three times this size is
+used (to allow for buffering "before" and "after" lines). An error occurs if a
+line overflows the buffer.
+.P
+Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the greater.
+BUFSIZ is defined in \fB\fP. When there is more than one pattern
+(specified by the use of \fB-e\fP and/or \fB-f\fP), each pattern is applied to
+each line in the order in which they are defined, except that all the \fB-e\fP
+patterns are tried before the \fB-f\fP patterns.
+.P
+By default, as soon as one pattern matches a line, no further patterns are
+considered. However, if \fB--colour\fP (or \fB--color\fP) is used to colour the
+matching substrings, or if \fB--only-matching\fP, \fB--file-offsets\fP, or
+\fB--line-offsets\fP is used to output only the part of the line that matched
+(either shown literally, or as an offset), scanning resumes immediately
+following the match, so that further matches on the same line can be found. If
+there are multiple patterns, they are all tried on the remainder of the line,
+but patterns that follow the one that matched are not tried on the earlier part
+of the line.
+.P
+This behaviour means that the order in which multiple patterns are specified
+can affect the output when one of the above options is used. This is no longer
+the same behaviour as GNU grep, which now manages to display earlier matches
+for later patterns (as long as there is no overlap).
+.P
+Patterns that can match an empty string are accepted, but empty string
+matches are never recognized. An example is the pattern "(super)?(man)?", in
+which all components are optional. This pattern finds all occurrences of both
+"super" and "man"; the output differs from matching with "super|man" when only
+the matching substrings are being shown.
+.P
+If the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variable is set,
+\fBpcregrep\fP uses the value to set a locale when calling the PCRE library.
+The \fB--locale\fP option can be used to override this.
+.P
+\fBzpcregrep\fR is a wrapper script that allows pcregrep to work on
+gzip compressed files.
+.
+.
+.SH "SUPPORT FOR COMPRESSED FILES"
+.rs
+.sp
+It is possible to compile \fBpcregrep\fP so that it uses \fBlibz\fP or
+\fBlibbz2\fP to read files whose names end in \fB.gz\fP or \fB.bz2\fP,
+respectively. You can find out whether your binary has support for one or both
+of these file types by running it with the \fB--help\fP option. If the
+appropriate support is not present, files are treated as plain text. The
+standard input is always so treated.
+.
+.
+.SH "BINARY FILES"
+.rs
+.sp
+By default, a file that contains a binary zero byte within the first 1024 bytes
+is identified as a binary file, and is processed specially. (GNU grep also
+identifies binary files in this manner.) See the \fB--binary-files\fP option
+for a means of changing the way binary files are handled.
+.
+.
+.SH OPTIONS
+.rs
+.sp
+The order in which some of the options appear can affect the output. For
+example, both the \fB-h\fP and \fB-l\fP options affect the printing of file
+names. Whichever comes later in the command line will be the one that takes
+effect. Similarly, except where noted below, if an option is given twice, the
+later setting is used. Numerical values for options may be followed by K or M,
+to signify multiplication by 1024 or 1024*1024 respectively.
+.TP 10
+\fB--\fP
+This terminates the list of options. It is useful if the next item on the
+command line starts with a hyphen but is not an option. This allows for the
+processing of patterns and filenames that start with hyphens.
+.TP
+\fB-A\fP \fInumber\fP, \fB--after-context=\fP\fInumber\fP
+Output \fInumber\fP lines of context after each matching line. If filenames
+and/or line numbers are being output, a hyphen separator is used instead of a
+colon for the context lines. A line containing "--" is output between each
+group of lines, unless they are in fact contiguous in the input file. The value
+of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
+guarantees to have up to 8K of following text available for context output.
+.TP
+\fB-a\fP, \fB--text\fP
+Treat binary files as text. This is equivalent to
+\fB--binary-files\fP=\fItext\fP.
+.TP
+\fB-B\fP \fInumber\fP, \fB--before-context=\fP\fInumber\fP
+Output \fInumber\fP lines of context before each matching line. If filenames
+and/or line numbers are being output, a hyphen separator is used instead of a
+colon for the context lines. A line containing "--" is output between each
+group of lines, unless they are in fact contiguous in the input file. The value
+of \fInumber\fP is expected to be relatively small. However, \fBpcregrep\fP
+guarantees to have up to 8K of preceding text available for context output.
+.TP
+\fB--binary-files=\fP\fIword\fP
+Specify how binary files are to be processed. If the word is "binary" (the
+default), pattern matching is performed on binary files, but the only output is
+"Binary file  matches" when a match succeeds. If the word is "text",
+which is equivalent to the \fB-a\fP or \fB--text\fP option, binary files are
+processed in the same way as any other file. In this case, when a match
+succeeds, the output may be binary garbage, which can have nasty effects if
+sent to a terminal. If the word is "without-match", which is equivalent to the
+\fB-I\fP option, binary files are not processed at all; they are assumed not to
+be of interest.
+.TP
+\fB--buffer-size=\fP\fInumber\fP
+Set the parameter that controls how much memory is used for buffering files
+that are being scanned.
+.TP
+\fB-C\fP \fInumber\fP, \fB--context=\fP\fInumber\fP
+Output \fInumber\fP lines of context both before and after each matching line.
+This is equivalent to setting both \fB-A\fP and \fB-B\fP to the same value.
+.TP
+\fB-c\fP, \fB--count\fP
+Do not output individual lines from the files that are being scanned; instead
+output the number of lines that would otherwise have been shown. If no lines
+are selected, the number zero is output. If several files are are being
+scanned, a count is output for each of them. However, if the
+\fB--files-with-matches\fP option is also used, only those files whose counts
+are greater than zero are listed. When \fB-c\fP is used, the \fB-A\fP,
+\fB-B\fP, and \fB-C\fP options are ignored.
+.TP
+\fB--colour\fP, \fB--color\fP
+If this option is given without any data, it is equivalent to "--colour=auto".
+If data is required, it must be given in the same shell item, separated by an
+equals sign.
+.TP
+\fB--colour=\fP\fIvalue\fP, \fB--color=\fP\fIvalue\fP
+This option specifies under what circumstances the parts of a line that matched
+a pattern should be coloured in the output. By default, the output is not
+coloured. The value (which is optional, see above) may be "never", "always", or
+"auto". In the latter case, colouring happens only if the standard output is
+connected to a terminal. More resources are used when colouring is enabled,
+because \fBpcregrep\fP has to search for all possible matches in a line, not
+just one, in order to colour them all.
+.sp
+The colour that is used can be specified by setting the environment variable
+PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
+string of two numbers, separated by a semicolon. They are copied directly into
+the control string for setting colour on a terminal, so it is your
+responsibility to ensure that they make sense. If neither of the environment
+variables is set, the default is "1;31", which gives red.
+.TP
+\fB-D\fP \fIaction\fP, \fB--devices=\fP\fIaction\fP
+If an input path is not a regular file or a directory, "action" specifies how
+it is to be processed. Valid values are "read" (the default) or "skip"
+(silently skip the path).
+.TP
+\fB-d\fP \fIaction\fP, \fB--directories=\fP\fIaction\fP
+If an input path is a directory, "action" specifies how it is to be processed.
+Valid values are "read" (the default in non-Windows environments, for
+compatibility with GNU grep), "recurse" (equivalent to the \fB-r\fP option), or
+"skip" (silently skip the path, the default in Windows environments). In the
+"read" case, directories are read as if they were ordinary files. In some
+operating systems the effect of reading a directory like this is an immediate
+end-of-file; in others it may provoke an error.
+.TP
+\fB-e\fP \fIpattern\fP, \fB--regex=\fP\fIpattern\fP, \fB--regexp=\fP\fIpattern\fP
+Specify a pattern to be matched. This option can be used multiple times in
+order to specify several patterns. It can also be used as a way of specifying a
+single pattern that starts with a hyphen. When \fB-e\fP is used, no argument
+pattern is taken from the command line; all arguments are treated as file
+names. There is no limit to the number of patterns. They are applied to each
+line in the order in which they are defined until one matches.
+.sp
+If \fB-f\fP is used with \fB-e\fP, the command line patterns are matched first,
+followed by the patterns from the file(s), independent of the order in which
+these options are specified. Note that multiple use of \fB-e\fP is not the same
+as a single pattern with alternatives. For example, X|Y finds the first
+character in a line that is X or Y, whereas if the two patterns are given
+separately, with X first, \fBpcregrep\fP finds X if it is present, even if it
+follows Y in the line. It finds Y only if there is no X in the line. This
+matters only if you are using \fB-o\fP or \fB--colo(u)r\fP to show the part(s)
+of the line that matched.
+.TP
+\fB--exclude\fP=\fIpattern\fP
+Files (but not directories) whose names match the pattern are skipped without
+being processed. This applies to all files, whether listed on the command line,
+obtained from \fB--file-list\fP, or by scanning a directory. The pattern is a
+PCRE regular expression, and is matched against the final component of the file
+name, not the entire path. The \fB-F\fP, \fB-w\fP, and \fB-x\fP options do not
+apply to this pattern. The option may be given any number of times in order to
+specify multiple patterns. If a file name matches both an \fB--include\fP
+and an \fB--exclude\fP pattern, it is excluded. There is no short form for this
+option.
+.TP
+\fB--exclude-from=\fP\fIfilename\fP
+Treat each non-empty line of the file as the data for an \fB--exclude\fP
+option. What constitutes a newline when reading the file is the operating
+system's default. The \fB--newline\fP option has no effect on this option. This
+option may be given more than once in order to specify a number of files to
+read.
+.TP
+\fB--exclude-dir\fP=\fIpattern\fP
+Directories whose names match the pattern are skipped without being processed,
+whatever the setting of the \fB--recursive\fP option. This applies to all
+directories, whether listed on the command line, obtained from
+\fB--file-list\fP, or by scanning a parent directory. The pattern is a PCRE
+regular expression, and is matched against the final component of the directory
+name, not the entire path. The \fB-F\fP, \fB-w\fP, and \fB-x\fP options do not
+apply to this pattern. The option may be given any number of times in order to
+specify more than one pattern. If a directory matches both \fB--include-dir\fP
+and \fB--exclude-dir\fP, it is excluded. There is no short form for this
+option.
+.TP
+\fB-F\fP, \fB--fixed-strings\fP
+Interpret each data-matching pattern as a list of fixed strings, separated by
+newlines, instead of as a regular expression. What constitutes a newline for
+this purpose is controlled by the \fB--newline\fP option. The \fB-w\fP (match
+as a word) and \fB-x\fP (match whole line) options can be used with \fB-F\fP.
+They apply to each of the fixed strings. A line is selected if any of the fixed
+strings are found in it (subject to \fB-w\fP or \fB-x\fP, if present). This
+option applies only to the patterns that are matched against the contents of
+files; it does not apply to patterns specified by any of the \fB--include\fP or
+\fB--exclude\fP options.
+.TP
+\fB-f\fP \fIfilename\fP, \fB--file=\fP\fIfilename\fP
+Read patterns from the file, one per line, and match them against
+each line of input. What constitutes a newline when reading the file is the
+operating system's default. The \fB--newline\fP option has no effect on this
+option. Trailing white space is removed from each line, and blank lines are
+ignored. An empty file contains no patterns and therefore matches nothing. See
+also the comments about multiple patterns versus a single pattern with
+alternatives in the description of \fB-e\fP above.
+.sp
+If this option is given more than once, all the specified files are
+read. A data line is output if any of the patterns match it. A filename can
+be given as "-" to refer to the standard input. When \fB-f\fP is used, patterns
+specified on the command line using \fB-e\fP may also be present; they are
+tested before the file's patterns. However, no other pattern is taken from the
+command line; all arguments are treated as the names of paths to be searched.
+.TP
+\fB--file-list\fP=\fIfilename\fP
+Read a list of files and/or directories that are to be scanned from the given
+file, one per line. Trailing white space is removed from each line, and blank
+lines are ignored. These paths are processed before any that are listed on the
+command line. The filename can be given as "-" to refer to the standard input.
+If \fB--file\fP and \fB--file-list\fP are both specified as "-", patterns are
+read first. This is useful only when the standard input is a terminal, from
+which further lines (the list of files) can be read after an end-of-file
+indication. If this option is given more than once, all the specified files are
+read.
+.TP
+\fB--file-offsets\fP
+Instead of showing lines or parts of lines that match, show each match as an
+offset from the start of the file and a length, separated by a comma. In this
+mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP
+options are ignored. If there is more than one match in a line, each of them is
+shown separately. This option is mutually exclusive with \fB--line-offsets\fP
+and \fB--only-matching\fP.
+.TP
+\fB-H\fP, \fB--with-filename\fP
+Force the inclusion of the filename at the start of output lines when searching
+a single file. By default, the filename is not shown in this case. For matching
+lines, the filename is followed by a colon; for context lines, a hyphen
+separator is used. If a line number is also being output, it follows the file
+name.
+.TP
+\fB-h\fP, \fB--no-filename\fP
+Suppress the output filenames when searching multiple files. By default,
+filenames are shown when multiple files are searched. For matching lines, the
+filename is followed by a colon; for context lines, a hyphen separator is used.
+If a line number is also being output, it follows the file name.
+.TP
+\fB--help\fP
+Output a help message, giving brief details of the command options and file
+type support, and then exit. Anything else on the command line is
+ignored.
+.TP
+\fB-I\fP
+Treat binary files as never matching. This is equivalent to
+\fB--binary-files\fP=\fIwithout-match\fP.
+.TP
+\fB-i\fP, \fB--ignore-case\fP
+Ignore upper/lower case distinctions during comparisons.
+.TP
+\fB--include\fP=\fIpattern\fP
+If any \fB--include\fP patterns are specified, the only files that are
+processed are those that match one of the patterns (and do not match an
+\fB--exclude\fP pattern). This option does not affect directories, but it
+applies to all files, whether listed on the command line, obtained from
+\fB--file-list\fP, or by scanning a directory. The pattern is a PCRE regular
+expression, and is matched against the final component of the file name, not
+the entire path. The \fB-F\fP, \fB-w\fP, and \fB-x\fP options do not apply to
+this pattern. The option may be given any number of times. If a file name
+matches both an \fB--include\fP and an \fB--exclude\fP pattern, it is excluded.
+There is no short form for this option.
+.TP
+\fB--include-from=\fP\fIfilename\fP
+Treat each non-empty line of the file as the data for an \fB--include\fP
+option. What constitutes a newline for this purpose is the operating system's
+default. The \fB--newline\fP option has no effect on this option. This option
+may be given any number of times; all the files are read.
+.TP
+\fB--include-dir\fP=\fIpattern\fP
+If any \fB--include-dir\fP patterns are specified, the only directories that
+are processed are those that match one of the patterns (and do not match an
+\fB--exclude-dir\fP pattern). This applies to all directories, whether listed
+on the command line, obtained from \fB--file-list\fP, or by scanning a parent
+directory. The pattern is a PCRE regular expression, and is matched against the
+final component of the directory name, not the entire path. The \fB-F\fP,
+\fB-w\fP, and \fB-x\fP options do not apply to this pattern. The option may be
+given any number of times. If a directory matches both \fB--include-dir\fP and
+\fB--exclude-dir\fP, it is excluded. There is no short form for this option.
+.TP
+\fB-L\fP, \fB--files-without-match\fP
+Instead of outputting lines from the files, just output the names of the files
+that do not contain any lines that would have been output. Each file name is
+output once, on a separate line.
+.TP
+\fB-l\fP, \fB--files-with-matches\fP
+Instead of outputting lines from the files, just output the names of the files
+containing lines that would have been output. Each file name is output
+once, on a separate line. Searching normally stops as soon as a matching line
+is found in a file. However, if the \fB-c\fP (count) option is also used,
+matching continues in order to obtain the correct count, and those files that
+have at least one match are listed along with their counts. Using this option
+with \fB-c\fP is a way of suppressing the listing of files with no matches.
+.TP
+\fB--label\fP=\fIname\fP
+This option supplies a name to be used for the standard input when file names
+are being output. If not supplied, "(standard input)" is used. There is no
+short form for this option.
+.TP
+\fB--line-buffered\fP
+When this option is given, input is read and processed line by line, and the
+output is flushed after each write. By default, input is read in large chunks,
+unless \fBpcregrep\fP can determine that it is reading from a terminal (which
+is currently possible only in Unix-like environments). Output to terminal is
+normally automatically flushed by the operating system. This option can be
+useful when the input or output is attached to a pipe and you do not want
+\fBpcregrep\fP to buffer up large amounts of data. However, its use will affect
+performance, and the \fB-M\fP (multiline) option ceases to work.
+.TP
+\fB--line-offsets\fP
+Instead of showing lines or parts of lines that match, show each match as a
+line number, the offset from the start of the line, and a length. The line
+number is terminated by a colon (as usual; see the \fB-n\fP option), and the
+offset and length are separated by a comma. In this mode, no context is shown.
+That is, the \fB-A\fP, \fB-B\fP, and \fB-C\fP options are ignored. If there is
+more than one match in a line, each of them is shown separately. This option is
+mutually exclusive with \fB--file-offsets\fP and \fB--only-matching\fP.
+.TP
+\fB--locale\fP=\fIlocale-name\fP
+This option specifies a locale to be used for pattern matching. It overrides
+the value in the \fBLC_ALL\fP or \fBLC_CTYPE\fP environment variables. If no
+locale is specified, the PCRE library's default (usually the "C" locale) is
+used. There is no short form for this option.
+.TP
+\fB--match-limit\fP=\fInumber\fP
+Processing some regular expression patterns can require a very large amount of
+memory, leading in some cases to a program crash if not enough is available.
+Other patterns may take a very long time to search for all possible matching
+strings. The \fBpcre_exec()\fP function that is called by \fBpcregrep\fP to do
+the matching has two parameters that can limit the resources that it uses.
+.sp
+The \fB--match-limit\fP option provides a means of limiting resource usage
+when processing patterns that are not going to match, but which have a very
+large number of possibilities in their search trees. The classic example is a
+pattern that uses nested unlimited repeats. Internally, PCRE uses a function
+called \fBmatch()\fP which it calls repeatedly (sometimes recursively). The
+limit set by \fB--match-limit\fP is imposed on the number of times this
+function is called during a match, which has the effect of limiting the amount
+of backtracking that can take place.
+.sp
+The \fB--recursion-limit\fP option is similar to \fB--match-limit\fP, but
+instead of limiting the total number of times that \fBmatch()\fP is called, it
+limits the depth of recursive calls, which in turn limits the amount of memory
+that can be used. The recursion depth is a smaller number than the total number
+of calls, because not all calls to \fBmatch()\fP are recursive. This limit is
+of use only if it is set smaller than \fB--match-limit\fP.
+.sp
+There are no short forms for these options. The default settings are specified
+when the PCRE library is compiled, with the default default being 10 million.
+.TP
+\fB-M\fP, \fB--multiline\fP
+Allow patterns to match more than one line. When this option is given, patterns
+may usefully contain literal newline characters and internal occurrences of ^
+and $ characters. The output for a successful match may consist of more than
+one line, the last of which is the one in which the match ended. If the matched
+string ends with a newline sequence the output ends at the end of that line.
+.sp
+When this option is set, the PCRE library is called in "multiline" mode.
+There is a limit to the number of lines that can be matched, imposed by the way
+that \fBpcregrep\fP buffers the input file as it scans it. However,
+\fBpcregrep\fP ensures that at least 8K characters or the rest of the document
+(whichever is the shorter) are available for forward matching, and similarly
+the previous 8K characters (or all the previous characters, if fewer than 8K)
+are guaranteed to be available for lookbehind assertions. This option does not
+work when input is read line by line (see \fP--line-buffered\fP.)
+.TP
+\fB-N\fP \fInewline-type\fP, \fB--newline\fP=\fInewline-type\fP
+The PCRE library supports five different conventions for indicating
+the ends of lines. They are the single-character sequences CR (carriage return)
+and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
+which recognizes any of the preceding three types, and an "any" convention, in
+which any Unicode line ending sequence is assumed to end a line. The Unicode
+sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
+(form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
+PS (paragraph separator, U+2029).
+.sp
+When the PCRE library is built, a default line-ending sequence is specified.
+This is normally the standard sequence for the operating system. Unless
+otherwise specified by this option, \fBpcregrep\fP uses the library's default.
+The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
+makes it possible to use \fBpcregrep\fP to scan files that have come from other
+environments without having to modify their line endings. If the data that is
+being scanned does not agree with the convention set by this option,
+\fBpcregrep\fP may behave in strange ways. Note that this option does not
+apply to files specified by the \fB-f\fP, \fB--exclude-from\fP, or
+\fB--include-from\fP options, which are expected to use the operating system's
+standard newline sequence.
+.TP
+\fB-n\fP, \fB--line-number\fP
+Precede each output line by its line number in the file, followed by a colon
+for matching lines or a hyphen for context lines. If the filename is also being
+output, it precedes the line number. This option is forced if
+\fB--line-offsets\fP is used.
+.TP
+\fB--no-jit\fP
+If the PCRE library is built with support for just-in-time compiling (which
+speeds up matching), \fBpcregrep\fP automatically makes use of this, unless it
+was explicitly disabled at build time. This option can be used to disable the
+use of JIT at run time. It is provided for testing and working round problems.
+It should never be needed in normal use.
+.TP
+\fB-o\fP, \fB--only-matching\fP
+Show only the part of the line that matched a pattern instead of the whole
+line. In this mode, no context is shown. That is, the \fB-A\fP, \fB-B\fP, and
+\fB-C\fP options are ignored. If there is more than one match in a line, each
+of them is shown separately. If \fB-o\fP is combined with \fB-v\fP (invert the
+sense of the match to find non-matching lines), no output is generated, but the
+return code is set appropriately. If the matched portion of the line is empty,
+nothing is output unless the file name or line number are being printed, in
+which case they are shown on an otherwise empty line. This option is mutually
+exclusive with \fB--file-offsets\fP and \fB--line-offsets\fP.
+.TP
+\fB-o\fP\fInumber\fP, \fB--only-matching\fP=\fInumber\fP
+Show only the part of the line that matched the capturing parentheses of the
+given number. Up to 32 capturing parentheses are supported, and -o0 is
+equivalent to \fB-o\fP without a number. Because these options can be given
+without an argument (see above), if an argument is present, it must be given in
+the same shell item, for example, -o3 or --only-matching=2. The comments given
+for the non-argument case above also apply to this case. If the specified
+capturing parentheses do not exist in the pattern, or were not set in the
+match, nothing is output unless the file name or line number are being printed.
+.sp
+If this option is given multiple times, multiple substrings are output, in the
+order the options are given. For example, -o3 -o1 -o3 causes the substrings
+matched by capturing parentheses 3 and 1 and then 3 again to be output. By
+default, there is no separator (but see the next option).
+.TP
+\fB--om-separator\fP=\fItext\fP
+Specify a separating string for multiple occurrences of \fB-o\fP. The default
+is an empty string. Separating strings are never coloured.
+.TP
+\fB-q\fP, \fB--quiet\fP
+Work quietly, that is, display nothing except error messages. The exit
+status indicates whether or not any matches were found.
+.TP
+\fB-r\fP, \fB--recursive\fP
+If any given path is a directory, recursively scan the files it contains,
+taking note of any \fB--include\fP and \fB--exclude\fP settings. By default, a
+directory is read as a normal file; in some operating systems this gives an
+immediate end-of-file. This option is a shorthand for setting the \fB-d\fP
+option to "recurse".
+.TP
+\fB--recursion-limit\fP=\fInumber\fP
+See \fB--match-limit\fP above.
+.TP
+\fB-s\fP, \fB--no-messages\fP
+Suppress error messages about non-existent or unreadable files. Such files are
+quietly skipped. However, the return code is still 2, even if matches were
+found in other files.
+.TP
+\fB-u\fP, \fB--utf-8\fP
+Operate in UTF-8 mode. This option is available only if PCRE has been compiled
+with UTF-8 support. All patterns (including those for any \fB--exclude\fP and
+\fB--include\fP options) and all subject lines that are scanned must be valid
+strings of UTF-8 characters.
+.TP
+\fB-V\fP, \fB--version\fP
+Write the version numbers of \fBpcregrep\fP and the PCRE library to the
+standard output and then exit. Anything else on the command line is
+ignored.
+.TP
+\fB-v\fP, \fB--invert-match\fP
+Invert the sense of the match, so that lines which do \fInot\fP match any of
+the patterns are the ones that are found.
+.TP
+\fB-w\fP, \fB--word-regex\fP, \fB--word-regexp\fP
+Force the patterns to match only whole words. This is equivalent to having \eb
+at the start and end of the pattern. This option applies only to the patterns
+that are matched against the contents of files; it does not apply to patterns
+specified by any of the \fB--include\fP or \fB--exclude\fP options.
+.TP
+\fB-x\fP, \fB--line-regex\fP, \fB--line-regexp\fP
+Force the patterns to be anchored (each must start matching at the beginning of
+a line) and in addition, require them to match entire lines. This is equivalent
+to having ^ and $ characters at the start and end of each alternative branch in
+every pattern. This option applies only to the patterns that are matched
+against the contents of files; it does not apply to patterns specified by any
+of the \fB--include\fP or \fB--exclude\fP options.
+.
+.
+.SH "ENVIRONMENT VARIABLES"
+.rs
+.sp
+The environment variables \fBLC_ALL\fP and \fBLC_CTYPE\fP are examined, in that
+order, for a locale. The first one that is set is used. This can be overridden
+by the \fB--locale\fP option. If no locale is set, the PCRE library's default
+(usually the "C" locale) is used.
+.
+.
+.SH "NEWLINES"
+.rs
+.sp
+The \fB-N\fP (\fB--newline\fP) option allows \fBpcregrep\fP to scan files with
+different newline conventions from the default. Any parts of the input files
+that are written to the standard output are copied identically, with whatever
+newline sequences they have in the input. However, the setting of this option
+does not affect the interpretation of files specified by the \fB-f\fP,
+\fB--exclude-from\fP, or \fB--include-from\fP options, which are assumed to use
+the operating system's standard newline sequence, nor does it affect the way in
+which \fBpcregrep\fP writes informational messages to the standard error and
+output streams. For these it uses the string "\en" to indicate newlines,
+relying on the C I/O library to convert this to an appropriate sequence.
+.
+.
+.SH "OPTIONS COMPATIBILITY"
+.rs
+.sp
+Many of the short and long forms of \fBpcregrep\fP's options are the same
+as in the GNU \fBgrep\fP program. Any long option of the form
+\fB--xxx-regexp\fP (GNU terminology) is also available as \fB--xxx-regex\fP
+(PCRE terminology). However, the \fB--file-list\fP, \fB--file-offsets\fP,
+\fB--include-dir\fP, \fB--line-offsets\fP, \fB--locale\fP, \fB--match-limit\fP,
+\fB-M\fP, \fB--multiline\fP, \fB-N\fP, \fB--newline\fP, \fB--om-separator\fP,
+\fB--recursion-limit\fP, \fB-u\fP, and \fB--utf-8\fP options are specific to
+\fBpcregrep\fP, as is the use of the \fB--only-matching\fP option with a
+capturing parentheses number.
+.P
+Although most of the common options work the same way, a few are different in
+\fBpcregrep\fP. For example, the \fB--include\fP option's argument is a glob
+for GNU \fBgrep\fP, but a regular expression for \fBpcregrep\fP. If both the
+\fB-c\fP and \fB-l\fP options are given, GNU grep lists only file names,
+without counts, but \fBpcregrep\fP gives the counts.
+.
+.
+.SH "OPTIONS WITH DATA"
+.rs
+.sp
+There are four different ways in which an option with data can be specified.
+If a short form option is used, the data may follow immediately, or (with one
+exception) in the next command line item. For example:
+.sp
+  -f/some/file
+  -f /some/file
+.sp
+The exception is the \fB-o\fP option, which may appear with or without data.
+Because of this, if data is present, it must follow immediately in the same
+item, for example -o3.
+.P
+If a long form option is used, the data may appear in the same command line
+item, separated by an equals character, or (with two exceptions) it may appear
+in the next command line item. For example:
+.sp
+  --file=/some/file
+  --file /some/file
+.sp
+Note, however, that if you want to supply a file name beginning with ~ as data
+in a shell command, and have the shell expand ~ to a home directory, you must
+separate the file name from the option, because the shell does not treat ~
+specially unless it is at the start of an item.
+.P
+The exceptions to the above are the \fB--colour\fP (or \fB--color\fP) and
+\fB--only-matching\fP options, for which the data is optional. If one of these
+options does have data, it must be given in the first form, using an equals
+character. Otherwise \fBpcregrep\fP will assume that it has no data.
+.
+.
+.SH "MATCHING ERRORS"
+.rs
+.sp
+It is possible to supply a regular expression that takes a very long time to
+fail to match certain lines. Such patterns normally involve nested indefinite
+repeats, for example: (a+)*\ed when matched against a line of a's with no final
+digit. The PCRE matching function has a resource limit that causes it to abort
+in these circumstances. If this happens, \fBpcregrep\fP outputs an error
+message and the line that caused the problem to the standard error stream. If
+there are more than 20 such errors, \fBpcregrep\fP gives up.
+.P
+The \fB--match-limit\fP option of \fBpcregrep\fP can be used to set the overall
+resource limit; there is a second option called \fB--recursion-limit\fP that
+sets a limit on the amount of memory (usually stack) that is used (see the
+discussion of these options above).
+.
+.
+.SH DIAGNOSTICS
+.rs
+.sp
+Exit status is 0 if any matches were found, 1 if no matches were found, and 2
+for syntax errors, overlong lines, non-existent or inaccessible files (even if
+matches were found in other files) or too many matching errors. Using the
+\fB-s\fP option to suppress error messages about inaccessible files does not
+affect the return code.
+.
+.
+.SH "SEE ALSO"
+.rs
+.sp
+\fBpcrepattern\fP(3), \fBpcresyntax\fP(3), \fBpcretest\fP(1).
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 03 April 2014
+Copyright (c) 1997-2014 University of Cambridge.
+.fi
diff --git a/doc/pcregrep.txt b/doc/pcregrep.txt
new file mode 100644
index 0000000..97d9a7b
--- /dev/null
+++ b/doc/pcregrep.txt
@@ -0,0 +1,741 @@
+PCREGREP(1)                 General Commands Manual                PCREGREP(1)
+
+
+
+NAME
+       pcregrep - a grep with Perl-compatible regular expressions.
+
+SYNOPSIS
+       pcregrep [options] [long options] [pattern] [path1 path2 ...]
+
+
+DESCRIPTION
+
+       pcregrep  searches  files  for  character  patterns, in the same way as
+       other grep commands do, but it uses the PCRE regular expression library
+       to support patterns that are compatible with the regular expressions of
+       Perl 5. See pcresyntax(3) for a quick-reference summary of pattern syn-
+       tax,  or pcrepattern(3) for a full description of the syntax and seman-
+       tics of the regular expressions that PCRE supports.
+
+       Patterns, whether supplied on the command line or in a  separate  file,
+       are given without delimiters. For example:
+
+         pcregrep Thursday /etc/motd
+
+       If you attempt to use delimiters (for example, by surrounding a pattern
+       with slashes, as is common in Perl scripts), they  are  interpreted  as
+       part  of  the pattern. Quotes can of course be used to delimit patterns
+       on the command line because they are  interpreted  by  the  shell,  and
+       indeed  quotes  are required if a pattern contains white space or shell
+       metacharacters.
+
+       The first argument that follows any option settings is treated  as  the
+       single  pattern  to be matched when neither -e nor -f is present.  Con-
+       versely, when one or both of these options are  used  to  specify  pat-
+       terns, all arguments are treated as path names. At least one of -e, -f,
+       or an argument pattern must be provided.
+
+       If no files are specified, pcregrep reads the standard input. The stan-
+       dard  input  can  also  be  referenced by a name consisting of a single
+       hyphen.  For example:
+
+         pcregrep some-pattern /file1 - /file3
+
+       By default, each line that matches a pattern is copied to the  standard
+       output,  and if there is more than one file, the file name is output at
+       the start of each line, followed by a colon. However, there are options
+       that  can  change  how  pcregrep  behaves. In particular, the -M option
+       makes it possible to search for patterns  that  span  line  boundaries.
+       What  defines  a  line  boundary  is  controlled  by the -N (--newline)
+       option.
+
+       The amount of memory used for buffering files that are being scanned is
+       controlled  by a parameter that can be set by the --buffer-size option.
+       The default value for this parameter  is  specified  when  pcregrep  is
+       built,  with  the  default  default  being 20K. A block of memory three
+       times this size is used (to allow for buffering  "before"  and  "after"
+       lines). An error occurs if a line overflows the buffer.
+
+       Patterns  can  be  no  longer than 8K or BUFSIZ bytes, whichever is the
+       greater.  BUFSIZ is defined in . When there is more  than  one
+       pattern (specified by the use of -e and/or -f), each pattern is applied
+       to each line in the order in which they are defined,  except  that  all
+       the -e patterns are tried before the -f patterns.
+
+       By  default, as soon as one pattern matches a line, no further patterns
+       are considered. However, if --colour (or --color) is used to colour the
+       matching  substrings, or if --only-matching, --file-offsets, or --line-
+       offsets is used to output only  the  part  of  the  line  that  matched
+       (either shown literally, or as an offset), scanning resumes immediately
+       following the match, so that further matches on the same  line  can  be
+       found.  If  there  are  multiple  patterns,  they  are all tried on the
+       remainder of the line, but patterns that follow the  one  that  matched
+       are not tried on the earlier part of the line.
+
+       This  behaviour  means  that  the  order in which multiple patterns are
+       specified can affect the output when one of the above options is  used.
+       This  is no longer the same behaviour as GNU grep, which now manages to
+       display earlier matches for later patterns (as  long  as  there  is  no
+       overlap).
+
+       Patterns  that can match an empty string are accepted, but empty string
+       matches   are   never   recognized.   An   example   is   the   pattern
+       "(super)?(man)?",  in  which  all components are optional. This pattern
+       finds all occurrences of both "super" and  "man";  the  output  differs
+       from  matching  with  "super|man" when only the matching substrings are
+       being shown.
+
+       If the LC_ALL or LC_CTYPE environment variable is  set,  pcregrep  uses
+       the  value to set a locale when calling the PCRE library.  The --locale
+       option can be used to override this.
+
+
+SUPPORT FOR COMPRESSED FILES
+
+       It is possible to compile pcregrep so that it uses libz  or  libbz2  to
+       read  files  whose names end in .gz or .bz2, respectively. You can find
+       out whether your binary has support for one or both of these file types
+       by running it with the --help option. If the appropriate support is not
+       present, files are treated as plain text. The standard input is  always
+       so treated.
+
+
+BINARY FILES
+
+       By  default,  a  file that contains a binary zero byte within the first
+       1024 bytes is identified as a binary file, and is processed  specially.
+       (GNU  grep  also  identifies  binary  files  in  this  manner.) See the
+       --binary-files option for a means of changing the way binary files  are
+       handled.
+
+
+OPTIONS
+
+       The  order  in  which some of the options appear can affect the output.
+       For example, both the -h and -l options affect  the  printing  of  file
+       names.  Whichever  comes later in the command line will be the one that
+       takes effect. Similarly, except where noted  below,  if  an  option  is
+       given  twice,  the  later setting is used. Numerical values for options
+       may be followed by K  or  M,  to  signify  multiplication  by  1024  or
+       1024*1024 respectively.
+
+       --        This terminates the list of options. It is useful if the next
+                 item on the command line starts with a hyphen but is  not  an
+                 option.  This allows for the processing of patterns and file-
+                 names that start with hyphens.
+
+       -A number, --after-context=number
+                 Output number lines of context after each matching  line.  If
+                 filenames and/or line numbers are being output, a hyphen sep-
+                 arator is used instead of a colon for the  context  lines.  A
+                 line  containing  "--" is output between each group of lines,
+                 unless they are in fact contiguous in  the  input  file.  The
+                 value  of number is expected to be relatively small. However,
+                 pcregrep guarantees to have up to 8K of following text avail-
+                 able for context output.
+
+       -a, --text
+                 Treat  binary  files as text. This is equivalent to --binary-
+                 files=text.
+
+       -B number, --before-context=number
+                 Output number lines of context before each matching line.  If
+                 filenames and/or line numbers are being output, a hyphen sep-
+                 arator is used instead of a colon for the  context  lines.  A
+                 line  containing  "--" is output between each group of lines,
+                 unless they are in fact contiguous in  the  input  file.  The
+                 value  of number is expected to be relatively small. However,
+                 pcregrep guarantees to have up to 8K of preceding text avail-
+                 able for context output.
+
+       --binary-files=word
+                 Specify  how binary files are to be processed. If the word is
+                 "binary" (the default),  pattern  matching  is  performed  on
+                 binary  files,  but  the  only  output is "Binary file 
+                 matches" when a match succeeds. If the word is "text",  which
+                 is  equivalent  to  the -a or --text option, binary files are
+                 processed in the same way as any other file.  In  this  case,
+                 when  a  match  succeeds,  the  output may be binary garbage,
+                 which can have nasty effects if sent to a  terminal.  If  the
+                 word  is  "without-match",  which  is  equivalent  to  the -I
+                 option, binary files are  not  processed  at  all;  they  are
+                 assumed not to be of interest.
+
+       --buffer-size=number
+                 Set  the  parameter that controls how much memory is used for
+                 buffering files that are being scanned.
+
+       -C number, --context=number
+                 Output number lines of context both  before  and  after  each
+                 matching  line.  This is equivalent to setting both -A and -B
+                 to the same value.
+
+       -c, --count
+                 Do not output individual lines from the files that are  being
+                 scanned; instead output the number of lines that would other-
+                 wise have been shown. If no lines are  selected,  the  number
+                 zero  is  output.  If  several files are are being scanned, a
+                 count is output for each of them. However,  if  the  --files-
+                 with-matches  option  is  also  used,  only those files whose
+                 counts are greater than zero are listed. When -c is used, the
+                 -A, -B, and -C options are ignored.
+
+       --colour, --color
+                 If this option is given without any data, it is equivalent to
+                 "--colour=auto".  If data is required, it must  be  given  in
+                 the same shell item, separated by an equals sign.
+
+       --colour=value, --color=value
+                 This option specifies under what circumstances the parts of a
+                 line that matched a pattern should be coloured in the output.
+                 By  default,  the output is not coloured. The value (which is
+                 optional, see above) may be "never", "always", or "auto".  In
+                 the  latter case, colouring happens only if the standard out-
+                 put is connected to a terminal. More resources are used  when
+                 colouring  is enabled, because pcregrep has to search for all
+                 possible matches in a line, not just one, in order to  colour
+                 them all.
+
+                 The colour that is used can be specified by setting the envi-
+                 ronment variable PCREGREP_COLOUR or PCREGREP_COLOR. The value
+                 of this variable should be a string of two numbers, separated
+                 by a semicolon. They are copied  directly  into  the  control
+                 string  for  setting  colour  on  a  terminal,  so it is your
+                 responsibility to ensure that they make sense. If neither  of
+                 the  environment  variables  is  set,  the default is "1;31",
+                 which gives red.
+
+       -D action, --devices=action
+                 If an input path is  not  a  regular  file  or  a  directory,
+                 "action"  specifies  how  it is to be processed. Valid values
+                 are "read" (the default) or "skip" (silently skip the path).
+
+       -d action, --directories=action
+                 If an input path is a directory, "action" specifies how it is
+                 to  be  processed.   Valid  values are "read" (the default in
+                 non-Windows environments, for compatibility with  GNU  grep),
+                 "recurse"  (equivalent to the -r option), or "skip" (silently
+                 skip the path, the default in Windows environments).  In  the
+                 "read"  case,  directories  are read as if they were ordinary
+                 files. In some operating systems  the  effect  of  reading  a
+                 directory like this is an immediate end-of-file; in others it
+                 may provoke an error.
+
+       -e pattern, --regex=pattern, --regexp=pattern
+                 Specify a pattern to be matched. This option can be used mul-
+                 tiple times in order to specify several patterns. It can also
+                 be used as a way of specifying a single pattern  that  starts
+                 with  a hyphen. When -e is used, no argument pattern is taken
+                 from the command line; all  arguments  are  treated  as  file
+                 names.  There is no limit to the number of patterns. They are
+                 applied to each line in the order in which they  are  defined
+                 until one matches.
+
+                 If  -f is used with -e, the command line patterns are matched
+                 first, followed by the patterns from the file(s), independent
+                 of  the order in which these options are specified. Note that
+                 multiple use of -e is not the same as a single  pattern  with
+                 alternatives. For example, X|Y finds the first character in a
+                 line that is X or Y, whereas if the two  patterns  are  given
+                 separately,  with X first, pcregrep finds X if it is present,
+                 even if it follows Y in the line. It finds Y only if there is
+                 no  X  in  the line. This matters only if you are using -o or
+                 --colo(u)r to show the part(s) of the line that matched.
+
+       --exclude=pattern
+                 Files (but not directories) whose names match the pattern are
+                 skipped  without  being processed. This applies to all files,
+                 whether listed on the command  line,  obtained  from  --file-
+                 list, or by scanning a directory. The pattern is a PCRE regu-
+                 lar expression, and is matched against the final component of
+                 the  file  name,  not  the  entire  path.  The -F, -w, and -x
+                 options do not apply to this pattern. The option may be given
+                 any number of times in order to specify multiple patterns. If
+                 a file name matches both an --include and an  --exclude  pat-
+                 tern, it is excluded. There is no short form for this option.
+
+       --exclude-from=filename
+                 Treat  each  non-empty  line  of  the file as the data for an
+                 --exclude option. What constitutes a newline when reading the
+                 file  is the operating system's default. The --newline option
+                 has no effect on this option. This option may be  given  more
+                 than once in order to specify a number of files to read.
+
+       --exclude-dir=pattern
+                 Directories whose names match the pattern are skipped without
+                 being processed, whatever  the  setting  of  the  --recursive
+                 option.  This  applies  to all directories, whether listed on
+                 the command line, obtained from --file-list, or by scanning a
+                 parent  directory.  The pattern is a PCRE regular expression,
+                 and is matched against the final component of  the  directory
+                 name,  not the entire path. The -F, -w, and -x options do not
+                 apply to this pattern. The option may be given any number  of
+                 times  in order to specify more than one pattern. If a direc-
+                 tory matches both  --include-dir  and  --exclude-dir,  it  is
+                 excluded. There is no short form for this option.
+
+       -F, --fixed-strings
+                 Interpret  each  data-matching  pattern  as  a  list of fixed
+                 strings, separated by  newlines,  instead  of  as  a  regular
+                 expression.  What  constitutes  a newline for this purpose is
+                 controlled by the --newline option. The -w (match as a  word)
+                 and  -x (match whole line) options can be used with -F.  They
+                 apply to each of the fixed strings. A line is selected if any
+                 of the fixed strings are found in it (subject to -w or -x, if
+                 present). This option applies only to the patterns  that  are
+                 matched  against  the contents of files; it does not apply to
+                 patterns specified by  any  of  the  --include  or  --exclude
+                 options.
+
+       -f filename, --file=filename
+                 Read  patterns  from  the  file, one per line, and match them
+                 against each line of input. What constitutes a  newline  when
+                 reading  the  file  is  the  operating  system's default. The
+                 --newline option has no effect on this option. Trailing white
+                 space is removed from each line, and blank lines are ignored.
+                 An empty file contains  no  patterns  and  therefore  matches
+                 nothing. See also the comments about multiple patterns versus
+                 a single pattern with alternatives in the description  of  -e
+                 above.
+
+                 If  this  option  is  given more than once, all the specified
+                 files are read. A data line is output if any of the  patterns
+                 match  it.  A  filename  can  be given as "-" to refer to the
+                 standard input. When -f is used, patterns  specified  on  the
+                 command  line  using  -e may also be present; they are tested
+                 before the file's patterns.  However,  no  other  pattern  is
+                 taken from the command line; all arguments are treated as the
+                 names of paths to be searched.
+
+       --file-list=filename
+                 Read a list of  files  and/or  directories  that  are  to  be
+                 scanned  from  the  given  file, one per line. Trailing white
+                 space is removed from each line, and blank lines are ignored.
+                 These  paths  are processed before any that are listed on the
+                 command line. The filename can be given as "-"  to  refer  to
+                 the standard input.  If --file and --file-list are both spec-
+                 ified as "-", patterns are read first. This  is  useful  only
+                 when  the  standard  input  is a terminal, from which further
+                 lines (the list of files) can be read  after  an  end-of-file
+                 indication.  If  this option is given more than once, all the
+                 specified files are read.
+
+       --file-offsets
+                 Instead of showing lines or parts of lines that  match,  show
+                 each  match  as  an  offset  from the start of the file and a
+                 length, separated by a comma. In this  mode,  no  context  is
+                 shown.  That  is,  the -A, -B, and -C options are ignored. If
+                 there is more than one match in a line, each of them is shown
+                 separately.  This  option  is mutually exclusive with --line-
+                 offsets and --only-matching.
+
+       -H, --with-filename
+                 Force the inclusion of the filename at the  start  of  output
+                 lines  when searching a single file. By default, the filename
+                 is not shown in this case. For matching lines,  the  filename
+                 is followed by a colon; for context lines, a hyphen separator
+                 is used. If a line number is also being  output,  it  follows
+                 the file name.
+
+       -h, --no-filename
+                 Suppress  the output filenames when searching multiple files.
+                 By default, filenames  are  shown  when  multiple  files  are
+                 searched.  For  matching lines, the filename is followed by a
+                 colon; for context lines, a hyphen separator is used.   If  a
+                 line number is also being output, it follows the file name.
+
+       --help    Output  a  help  message, giving brief details of the command
+                 options and file type support, and then exit.  Anything  else
+                 on the command line is ignored.
+
+       -I        Treat  binary  files as never matching. This is equivalent to
+                 --binary-files=without-match.
+
+       -i, --ignore-case
+                 Ignore upper/lower case distinctions during comparisons.
+
+       --include=pattern
+                 If any --include patterns are specified, the only files  that
+                 are  processed  are those that match one of the patterns (and
+                 do not match an --exclude  pattern).  This  option  does  not
+                 affect  directories,  but  it  applies  to all files, whether
+                 listed on the command line, obtained from --file-list, or  by
+                 scanning  a  directory. The pattern is a PCRE regular expres-
+                 sion, and is matched against the final component of the  file
+                 name,  not the entire path. The -F, -w, and -x options do not
+                 apply to this pattern. The option may be given any number  of
+                 times.  If  a  file  name  matches  both  an --include and an
+                 --exclude pattern, it is excluded.  There is  no  short  form
+                 for this option.
+
+       --include-from=filename
+                 Treat  each  non-empty  line  of  the file as the data for an
+                 --include option. What constitutes a newline for this purpose
+                 is  the  operating system's default. The --newline option has
+                 no effect on this option. This option may be given any number
+                 of times; all the files are read.
+
+       --include-dir=pattern
+                 If  any --include-dir patterns are specified, the only direc-
+                 tories that are processed are those that  match  one  of  the
+                 patterns  (and  do  not match an --exclude-dir pattern). This
+                 applies to all directories, whether  listed  on  the  command
+                 line,  obtained  from  --file-list,  or  by scanning a parent
+                 directory. The pattern is a PCRE regular expression,  and  is
+                 matched  against  the  final component of the directory name,
+                 not the entire path. The -F, -w, and -x options do not  apply
+                 to this pattern. The option may be given any number of times.
+                 If a directory matches both --include-dir and  --exclude-dir,
+                 it is excluded. There is no short form for this option.
+
+       -L, --files-without-match
+                 Instead  of  outputting lines from the files, just output the
+                 names of the files that do not contain any lines  that  would
+                 have  been  output. Each file name is output once, on a sepa-
+                 rate line.
+
+       -l, --files-with-matches
+                 Instead of outputting lines from the files, just  output  the
+                 names of the files containing lines that would have been out-
+                 put. Each file name is  output  once,  on  a  separate  line.
+                 Searching  normally stops as soon as a matching line is found
+                 in a file. However, if the -c (count) option  is  also  used,
+                 matching  continues in order to obtain the correct count, and
+                 those files that have at least one  match  are  listed  along
+                 with their counts. Using this option with -c is a way of sup-
+                 pressing the listing of files with no matches.
+
+       --label=name
+                 This option supplies a name to be used for the standard input
+                 when file names are being output. If not supplied, "(standard
+                 input)" is used. There is no short form for this option.
+
+       --line-buffered
+                 When this option is given, input is read and  processed  line
+                 by  line,  and  the  output  is  flushed after each write. By
+                 default, input is read in large chunks, unless  pcregrep  can
+                 determine  that  it is reading from a terminal (which is cur-
+                 rently possible only in Unix-like  environments).  Output  to
+                 terminal  is  normally automatically flushed by the operating
+                 system. This option can be useful when the input or output is
+                 attached  to a pipe and you do not want pcregrep to buffer up
+                 large amounts of data. However, its use will  affect  perfor-
+                 mance, and the -M (multiline) option ceases to work.
+
+       --line-offsets
+                 Instead  of  showing lines or parts of lines that match, show
+                 each match as a line number, the offset from the start of the
+                 line,  and a length. The line number is terminated by a colon
+                 (as usual; see the -n option), and the offset and length  are
+                 separated  by  a  comma.  In  this mode, no context is shown.
+                 That is, the -A, -B, and -C options are ignored. If there  is
+                 more  than  one  match in a line, each of them is shown sepa-
+                 rately. This option is mutually exclusive with --file-offsets
+                 and --only-matching.
+
+       --locale=locale-name
+                 This  option specifies a locale to be used for pattern match-
+                 ing. It overrides the value in the LC_ALL or  LC_CTYPE  envi-
+                 ronment  variables.  If  no  locale  is  specified,  the PCRE
+                 library's default (usually the "C" locale) is used. There  is
+                 no short form for this option.
+
+       --match-limit=number
+                 Processing  some  regular  expression  patterns can require a
+                 very large amount of memory, leading in some cases to a  pro-
+                 gram  crash  if  not enough is available.  Other patterns may
+                 take a very long time to search  for  all  possible  matching
+                 strings.  The pcre_exec() function that is called by pcregrep
+                 to do the matching has two  parameters  that  can  limit  the
+                 resources that it uses.
+
+                 The   --match-limit  option  provides  a  means  of  limiting
+                 resource usage when processing patterns that are not going to
+                 match, but which have a very large number of possibilities in
+                 their search trees. The classic example  is  a  pattern  that
+                 uses  nested unlimited repeats. Internally, PCRE uses a func-
+                 tion called match()  which  it  calls  repeatedly  (sometimes
+                 recursively).  The  limit  set by --match-limit is imposed on
+                 the number of times this function is called during  a  match,
+                 which  has  the effect of limiting the amount of backtracking
+                 that can take place.
+
+                 The --recursion-limit option is similar to --match-limit, but
+                 instead of limiting the total number of times that match() is
+                 called, it limits the depth of recursive calls, which in turn
+                 limits  the  amount of memory that can be used. The recursion
+                 depth is a smaller number than the  total  number  of  calls,
+                 because not all calls to match() are recursive. This limit is
+                 of use only if it is set smaller than --match-limit.
+
+                 There are no short forms for these options. The default  set-
+                 tings  are  specified when the PCRE library is compiled, with
+                 the default default being 10 million.
+
+       -M, --multiline
+                 Allow patterns to match more than one line. When this  option
+                 is given, patterns may usefully contain literal newline char-
+                 acters and internal occurrences of ^ and  $  characters.  The
+                 output  for  a  successful match may consist of more than one
+                 line, the last of which is the one in which the match  ended.
+                 If the matched string ends with a newline sequence the output
+                 ends at the end of that line.
+
+                 When this option is set, the PCRE library is called in  "mul-
+                 tiline"  mode.   There is a limit to the number of lines that
+                 can be matched, imposed by the way that pcregrep buffers  the
+                 input  file as it scans it. However, pcregrep ensures that at
+                 least 8K characters or the rest of the document (whichever is
+                 the  shorter)  are  available for forward matching, and simi-
+                 larly the previous 8K characters (or all the previous charac-
+                 ters,  if  fewer  than 8K) are guaranteed to be available for
+                 lookbehind assertions. This option does not work  when  input
+                 is read line by line (see --line-buffered.)
+
+       -N newline-type, --newline=newline-type
+                 The  PCRE  library  supports  five  different conventions for
+                 indicating the ends of lines. They are  the  single-character
+                 sequences  CR  (carriage  return) and LF (linefeed), the two-
+                 character sequence CRLF, an "anycrlf" convention, which  rec-
+                 ognizes  any  of the preceding three types, and an "any" con-
+                 vention, in which any Unicode line ending sequence is assumed
+                 to  end a line. The Unicode sequences are the three just men-
+                 tioned, plus  VT  (vertical  tab,  U+000B),  FF  (form  feed,
+                 U+000C),   NEL  (next  line,  U+0085),  LS  (line  separator,
+                 U+2028), and PS (paragraph separator, U+2029).
+
+                 When  the  PCRE  library  is  built,  a  default  line-ending
+                 sequence   is  specified.   This  is  normally  the  standard
+                 sequence for the operating system. Unless otherwise specified
+                 by  this  option,  pcregrep  uses the library's default.  The
+                 possible values for this option are CR, LF, CRLF, ANYCRLF, or
+                 ANY.  This  makes  it  possible to use pcregrep to scan files
+                 that have come from other environments without having to mod-
+                 ify  their  line  endings.  If the data that is being scanned
+                 does not agree with the convention set by this option,  pcre-
+                 grep  may  behave in strange ways. Note that this option does
+                 not apply to files specified by the  -f,  --exclude-from,  or
+                 --include-from options, which are expected to use the operat-
+                 ing system's standard newline sequence.
+
+       -n, --line-number
+                 Precede each output line by its line number in the file, fol-
+                 lowed  by  a colon for matching lines or a hyphen for context
+                 lines. If the filename is also being output, it precedes  the
+                 line number. This option is forced if --line-offsets is used.
+
+       --no-jit  If  the  PCRE  library is built with support for just-in-time
+                 compiling (which speeds up matching), pcregrep  automatically
+                 makes use of this, unless it was explicitly disabled at build
+                 time. This option can be used to disable the use  of  JIT  at
+                 run  time. It is provided for testing and working round prob-
+                 lems.  It should never be needed in normal use.
+
+       -o, --only-matching
+                 Show only the part of the line that matched a pattern instead
+                 of  the  whole  line. In this mode, no context is shown. That
+                 is, the -A, -B, and -C options are ignored. If there is  more
+                 than  one  match in a line, each of them is shown separately.
+                 If -o is combined with -v (invert the sense of the  match  to
+                 find  non-matching  lines),  no  output is generated, but the
+                 return code is set appropriately. If the matched  portion  of
+                 the  line is empty, nothing is output unless the file name or
+                 line number are being printed, in which case they  are  shown
+                 on an otherwise empty line. This option is mutually exclusive
+                 with --file-offsets and --line-offsets.
+
+       -onumber, --only-matching=number
+                 Show only the part of the line  that  matched  the  capturing
+                 parentheses of the given number. Up to 32 capturing parenthe-
+                 ses are supported, and -o0 is equivalent to -o without a num-
+                 ber.  Because  these options can be given without an argument
+                 (see above), if an argument is present, it must be  given  in
+                 the  same  shell item, for example, -o3 or --only-matching=2.
+                 The comments given for the non-argument case above also apply
+                 to  this  case. If the specified capturing parentheses do not
+                 exist in the pattern, or were not set in the  match,  nothing
+                 is  output  unless  the  file  name  or line number are being
+                 printed.
+
+                 If this option is given multiple times,  multiple  substrings
+                 are  output, in the order the options are given. For example,
+                 -o3 -o1 -o3 causes the substrings matched by capturing paren-
+                 theses  3  and  1  and then 3 again to be output. By default,
+                 there is no separator (but see the next option).
+
+       --om-separator=text
+                 Specify a separating string for multiple occurrences  of  -o.
+                 The  default is an empty string. Separating strings are never
+                 coloured.
+
+       -q, --quiet
+                 Work quietly, that is, display nothing except error messages.
+                 The  exit  status  indicates  whether or not any matches were
+                 found.
+
+       -r, --recursive
+                 If any given path is a directory, recursively scan the  files
+                 it  contains, taking note of any --include and --exclude set-
+                 tings. By default, a directory is read as a normal  file;  in
+                 some  operating  systems this gives an immediate end-of-file.
+                 This option is a shorthand  for  setting  the  -d  option  to
+                 "recurse".
+
+       --recursion-limit=number
+                 See --match-limit above.
+
+       -s, --no-messages
+                 Suppress  error  messages  about  non-existent  or unreadable
+                 files. Such files are quietly skipped.  However,  the  return
+                 code is still 2, even if matches were found in other files.
+
+       -u, --utf-8
+                 Operate  in UTF-8 mode. This option is available only if PCRE
+                 has been compiled with UTF-8 support. All patterns (including
+                 those  for  any --exclude and --include options) and all sub-
+                 ject lines that are scanned must be valid  strings  of  UTF-8
+                 characters.
+
+       -V, --version
+                 Write the version numbers of pcregrep and the PCRE library to
+                 the standard output and then exit. Anything else on the  com-
+                 mand line is ignored.
+
+       -v, --invert-match
+                 Invert  the  sense  of  the match, so that lines which do not
+                 match any of the patterns are the ones that are found.
+
+       -w, --word-regex, --word-regexp
+                 Force the patterns to match only whole words. This is equiva-
+                 lent  to  having \b at the start and end of the pattern. This
+                 option applies only to the patterns that are matched  against
+                 the  contents  of files; it does not apply to patterns speci-
+                 fied by any of the --include or --exclude options.
+
+       -x, --line-regex, --line-regexp
+                 Force the patterns to be anchored (each must  start  matching
+                 at  the beginning of a line) and in addition, require them to
+                 match entire lines. This is equivalent  to  having  ^  and  $
+                 characters at the start and end of each alternative branch in
+                 every pattern. This option applies only to the patterns  that
+                 are  matched against the contents of files; it does not apply
+                 to patterns specified by any of the  --include  or  --exclude
+                 options.
+
+
+ENVIRONMENT VARIABLES
+
+       The  environment  variables  LC_ALL  and LC_CTYPE are examined, in that
+       order, for a locale. The first one that is set is  used.  This  can  be
+       overridden  by  the  --locale  option.  If  no  locale is set, the PCRE
+       library's default (usually the "C" locale) is used.
+
+
+NEWLINES
+
+       The -N (--newline) option allows pcregrep to scan files with  different
+       newline conventions from the default. Any parts of the input files that
+       are written to the standard output are copied identically,  with  what-
+       ever  newline sequences they have in the input. However, the setting of
+       this option does not affect the interpretation of  files  specified  by
+       the -f, --exclude-from, or --include-from options, which are assumed to
+       use the operating system's  standard  newline  sequence,  nor  does  it
+       affect  the  way in which pcregrep writes informational messages to the
+       standard error and output streams. For these it uses the string "\n" to
+       indicate  newlines,  relying on the C I/O library to convert this to an
+       appropriate sequence.
+
+
+OPTIONS COMPATIBILITY
+
+       Many of the short and long forms of pcregrep's options are the same  as
+       in  the GNU grep program. Any long option of the form --xxx-regexp (GNU
+       terminology) is also available as --xxx-regex (PCRE terminology).  How-
+       ever,  the  --file-list, --file-offsets, --include-dir, --line-offsets,
+       --locale, --match-limit, -M, --multiline, -N,  --newline,  --om-separa-
+       tor,  --recursion-limit,  -u, and --utf-8 options are specific to pcre-
+       grep, as is the use of the  --only-matching  option  with  a  capturing
+       parentheses number.
+
+       Although  most  of the common options work the same way, a few are dif-
+       ferent in pcregrep. For example, the --include option's argument  is  a
+       glob  for  GNU grep, but a regular expression for pcregrep. If both the
+       -c and -l options are given, GNU grep lists only  file  names,  without
+       counts, but pcregrep gives the counts.
+
+
+OPTIONS WITH DATA
+
+       There are four different ways in which an option with data can be spec-
+       ified.  If a short form option is used, the  data  may  follow  immedi-
+       ately, or (with one exception) in the next command line item. For exam-
+       ple:
+
+         -f/some/file
+         -f /some/file
+
+       The exception is the -o option, which may appear with or without  data.
+       Because  of this, if data is present, it must follow immediately in the
+       same item, for example -o3.
+
+       If a long form option is used, the data may appear in the same  command
+       line  item,  separated by an equals character, or (with two exceptions)
+       it may appear in the next command line item. For example:
+
+         --file=/some/file
+         --file /some/file
+
+       Note, however, that if you want to supply a file name beginning with  ~
+       as  data  in  a  shell  command,  and have the shell expand ~ to a home
+       directory, you must separate the file name from the option, because the
+       shell does not treat ~ specially unless it is at the start of an item.
+
+       The  exceptions  to the above are the --colour (or --color) and --only-
+       matching options, for which the data  is  optional.  If  one  of  these
+       options  does  have  data, it must be given in the first form, using an
+       equals character. Otherwise pcregrep will assume that it has no data.
+
+
+MATCHING ERRORS
+
+       It is possible to supply a regular expression that takes  a  very  long
+       time  to  fail  to  match certain lines. Such patterns normally involve
+       nested indefinite repeats, for example: (a+)*\d when matched against  a
+       line  of  a's  with  no  final  digit. The PCRE matching function has a
+       resource limit that causes it to abort in these circumstances. If  this
+       happens, pcregrep outputs an error message and the line that caused the
+       problem to the standard error stream. If there are more  than  20  such
+       errors, pcregrep gives up.
+
+       The  --match-limit  option  of  pcregrep can be used to set the overall
+       resource limit; there is a second option called --recursion-limit  that
+       sets  a limit on the amount of memory (usually stack) that is used (see
+       the discussion of these options above).
+
+
+DIAGNOSTICS
+
+       Exit status is 0 if any matches were found, 1 if no matches were found,
+       and  2  for syntax errors, overlong lines, non-existent or inaccessible
+       files (even if matches were found in other files) or too many  matching
+       errors. Using the -s option to suppress error messages about inaccessi-
+       ble files does not affect the return code.
+
+
+SEE ALSO
+
+       pcrepattern(3), pcresyntax(3), pcretest(1).
+
+
+AUTHOR
+
+       Philip Hazel
+       University Computing Service
+       Cambridge CB2 3QH, England.
+
+
+REVISION
+
+       Last updated: 03 April 2014
+       Copyright (c) 1997-2014 University of Cambridge.
diff --git a/doc/pcrejit.3 b/doc/pcrejit.3
new file mode 100644
index 0000000..341403f
--- /dev/null
+++ b/doc/pcrejit.3
@@ -0,0 +1,431 @@
+.TH PCREJIT 3 "17 March 2013" "PCRE 8.33"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "PCRE JUST-IN-TIME COMPILER SUPPORT"
+.rs
+.sp
+Just-in-time compiling is a heavyweight optimization that can greatly speed up
+pattern matching. However, it comes at the cost of extra processing before the
+match is performed. Therefore, it is of most benefit when the same pattern is
+going to be matched many times. This does not necessarily mean many calls of a
+matching function; if the pattern is not anchored, matching attempts may take
+place many times at various positions in the subject, even for a single call.
+Therefore, if the subject string is very long, it may still pay to use JIT for
+one-off matches.
+.P
+JIT support applies only to the traditional Perl-compatible matching function.
+It does not apply when the DFA matching function is being used. The code for
+this support was written by Zoltan Herczeg.
+.
+.
+.SH "8-BIT, 16-BIT AND 32-BIT SUPPORT"
+.rs
+.sp
+JIT support is available for all of the 8-bit, 16-bit and 32-bit PCRE
+libraries. To keep this documentation simple, only the 8-bit interface is
+described in what follows. If you are using the 16-bit library, substitute the
+16-bit functions and 16-bit structures (for example, \fIpcre16_jit_stack\fP
+instead of \fIpcre_jit_stack\fP). If you are using the 32-bit library,
+substitute the 32-bit functions and 32-bit structures (for example,
+\fIpcre32_jit_stack\fP instead of \fIpcre_jit_stack\fP).
+.
+.
+.SH "AVAILABILITY OF JIT SUPPORT"
+.rs
+.sp
+JIT support is an optional feature of PCRE. The "configure" option --enable-jit
+(or equivalent CMake option) must be set when PCRE is built if you want to use
+JIT. The support is limited to the following hardware platforms:
+.sp
+  ARM v5, v7, and Thumb2
+  Intel x86 32-bit and 64-bit
+  MIPS 32-bit
+  Power PC 32-bit and 64-bit
+  SPARC 32-bit (experimental)
+.sp
+If --enable-jit is set on an unsupported platform, compilation fails.
+.P
+A program that is linked with PCRE 8.20 or later can tell if JIT support is
+available by calling \fBpcre_config()\fP with the PCRE_CONFIG_JIT option. The
+result is 1 when JIT is available, and 0 otherwise. However, a simple program
+does not need to check this in order to use JIT. The normal API is implemented
+in a way that falls back to the interpretive code if JIT is not available. For
+programs that need the best possible performance, there is also a "fast path"
+API that is JIT-specific.
+.P
+If your program may sometimes be linked with versions of PCRE that are older
+than 8.20, but you want to use JIT when it is available, you can test
+the values of PCRE_MAJOR and PCRE_MINOR, or the existence of a JIT macro such
+as PCRE_CONFIG_JIT, for compile-time control of your code.
+.
+.
+.SH "SIMPLE USE OF JIT"
+.rs
+.sp
+You have to do two things to make use of the JIT support in the simplest way:
+.sp
+  (1) Call \fBpcre_study()\fP with the PCRE_STUDY_JIT_COMPILE option for
+      each compiled pattern, and pass the resulting \fBpcre_extra\fP block to
+      \fBpcre_exec()\fP.
+.sp
+  (2) Use \fBpcre_free_study()\fP to free the \fBpcre_extra\fP block when it is
+      no longer needed, instead of just freeing it yourself. This ensures that
+      any JIT data is also freed.
+.sp
+For a program that may be linked with pre-8.20 versions of PCRE, you can insert
+.sp
+  #ifndef PCRE_STUDY_JIT_COMPILE
+  #define PCRE_STUDY_JIT_COMPILE 0
+  #endif
+.sp
+so that no option is passed to \fBpcre_study()\fP, and then use something like
+this to free the study data:
+.sp
+  #ifdef PCRE_CONFIG_JIT
+      pcre_free_study(study_ptr);
+  #else
+      pcre_free(study_ptr);
+  #endif
+.sp
+PCRE_STUDY_JIT_COMPILE requests the JIT compiler to generate code for complete
+matches. If you want to run partial matches using the PCRE_PARTIAL_HARD or
+PCRE_PARTIAL_SOFT options of \fBpcre_exec()\fP, you should set one or both of
+the following options in addition to, or instead of, PCRE_STUDY_JIT_COMPILE
+when you call \fBpcre_study()\fP:
+.sp
+  PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+  PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+.sp
+The JIT compiler generates different optimized code for each of the three
+modes (normal, soft partial, hard partial). When \fBpcre_exec()\fP is called,
+the appropriate code is run if it is available. Otherwise, the pattern is
+matched using interpretive code.
+.P
+In some circumstances you may need to call additional functions. These are
+described in the section entitled
+.\" HTML 
+.\" 
+"Controlling the JIT stack"
+.\"
+below.
+.P
+If JIT support is not available, PCRE_STUDY_JIT_COMPILE etc. are ignored, and
+no JIT data is created. Otherwise, the compiled pattern is passed to the JIT
+compiler, which turns it into machine code that executes much faster than the
+normal interpretive code. When \fBpcre_exec()\fP is passed a \fBpcre_extra\fP
+block containing a pointer to JIT code of the appropriate mode (normal or
+hard/soft partial), it obeys that code instead of running the interpreter. The
+result is identical, but the compiled JIT code runs much faster.
+.P
+There are some \fBpcre_exec()\fP options that are not supported for JIT
+execution. There are also some pattern items that JIT cannot handle. Details
+are given below. In both cases, execution automatically falls back to the
+interpretive code. If you want to know whether JIT was actually used for a
+particular match, you should arrange for a JIT callback function to be set up
+as described in the section entitled
+.\" HTML 
+.\" 
+"Controlling the JIT stack"
+.\"
+below, even if you do not need to supply a non-default JIT stack. Such a
+callback function is called whenever JIT code is about to be obeyed. If the
+execution options are not right for JIT execution, the callback function is not
+obeyed.
+.P
+If the JIT compiler finds an unsupported item, no JIT data is generated. You
+can find out if JIT execution is available after studying a pattern by calling
+\fBpcre_fullinfo()\fP with the PCRE_INFO_JIT option. A result of 1 means that
+JIT compilation was successful. A result of 0 means that JIT support is not
+available, or the pattern was not studied with PCRE_STUDY_JIT_COMPILE etc., or
+the JIT compiler was not able to handle the pattern.
+.P
+Once a pattern has been studied, with or without JIT, it can be used as many
+times as you like for matching different subject strings.
+.
+.
+.SH "UNSUPPORTED OPTIONS AND PATTERN ITEMS"
+.rs
+.sp
+The only \fBpcre_exec()\fP options that are supported for JIT execution are
+PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK, PCRE_NO_UTF32_CHECK, PCRE_NOTBOL,
+PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and
+PCRE_PARTIAL_SOFT.
+.P
+The only unsupported pattern items are \eC (match a single data unit) when
+running in a UTF mode, and a callout immediately before an assertion condition
+in a conditional group.
+.
+.
+.SH "RETURN VALUES FROM JIT EXECUTION"
+.rs
+.sp
+When a pattern is matched using JIT execution, the return values are the same
+as those given by the interpretive \fBpcre_exec()\fP code, with the addition of
+one new error code: PCRE_ERROR_JIT_STACKLIMIT. This means that the memory used
+for the JIT stack was insufficient. See
+.\" HTML 
+.\" 
+"Controlling the JIT stack"
+.\"
+below for a discussion of JIT stack usage. For compatibility with the
+interpretive \fBpcre_exec()\fP code, no more than two-thirds of the
+\fIovector\fP argument is used for passing back captured substrings.
+.P
+The error code PCRE_ERROR_MATCHLIMIT is returned by the JIT code if searching a
+very large pattern tree goes on for too long, as it is in the same circumstance
+when JIT is not used, but the details of exactly what is counted are not the
+same. The PCRE_ERROR_RECURSIONLIMIT error code is never returned by JIT
+execution.
+.
+.
+.SH "SAVING AND RESTORING COMPILED PATTERNS"
+.rs
+.sp
+The code that is generated by the JIT compiler is architecture-specific, and is
+also position dependent. For those reasons it cannot be saved (in a file or
+database) and restored later like the bytecode and other data of a compiled
+pattern. Saving and restoring compiled patterns is not something many people
+do. More detail about this facility is given in the
+.\" HREF
+\fBpcreprecompile\fP
+.\"
+documentation. It should be possible to run \fBpcre_study()\fP on a saved and
+restored pattern, and thereby recreate the JIT data, but because JIT
+compilation uses significant resources, it is probably not worth doing this;
+you might as well recompile the original pattern.
+.
+.
+.\" HTML 
+.SH "CONTROLLING THE JIT STACK"
+.rs
+.sp
+When the compiled JIT code runs, it needs a block of memory to use as a stack.
+By default, it uses 32K on the machine stack. However, some large or
+complicated patterns need more than this. The error PCRE_ERROR_JIT_STACKLIMIT
+is given when there is not enough stack. Three functions are provided for
+managing blocks of memory for use as JIT stacks. There is further discussion
+about the use of JIT stacks in the section entitled
+.\" HTML 
+.\" 
+"JIT stack FAQ"
+.\"
+below.
+.P
+The \fBpcre_jit_stack_alloc()\fP function creates a JIT stack. Its arguments
+are a starting size and a maximum size, and it returns a pointer to an opaque
+structure of type \fBpcre_jit_stack\fP, or NULL if there is an error. The
+\fBpcre_jit_stack_free()\fP function can be used to free a stack that is no
+longer needed. (For the technically minded: the address space is allocated by
+mmap or VirtualAlloc.)
+.P
+JIT uses far less memory for recursion than the interpretive code,
+and a maximum stack size of 512K to 1M should be more than enough for any
+pattern.
+.P
+The \fBpcre_assign_jit_stack()\fP function specifies which stack JIT code
+should use. Its arguments are as follows:
+.sp
+  pcre_extra         *extra
+  pcre_jit_callback  callback
+  void               *data
+.sp
+The \fIextra\fP argument must be the result of studying a pattern with
+PCRE_STUDY_JIT_COMPILE etc. There are three cases for the values of the other
+two options:
+.sp
+  (1) If \fIcallback\fP is NULL and \fIdata\fP is NULL, an internal 32K block
+      on the machine stack is used.
+.sp
+  (2) If \fIcallback\fP is NULL and \fIdata\fP is not NULL, \fIdata\fP must be
+      a valid JIT stack, the result of calling \fBpcre_jit_stack_alloc()\fP.
+.sp
+  (3) If \fIcallback\fP is not NULL, it must point to a function that is
+      called with \fIdata\fP as an argument at the start of matching, in
+      order to set up a JIT stack. If the return from the callback
+      function is NULL, the internal 32K stack is used; otherwise the
+      return value must be a valid JIT stack, the result of calling
+      \fBpcre_jit_stack_alloc()\fP.
+.sp
+A callback function is obeyed whenever JIT code is about to be run; it is not
+obeyed when \fBpcre_exec()\fP is called with options that are incompatible for
+JIT execution. A callback function can therefore be used to determine whether a
+match operation was executed by JIT or by the interpreter.
+.P
+You may safely use the same JIT stack for more than one pattern (either by
+assigning directly or by callback), as long as the patterns are all matched
+sequentially in the same thread. In a multithread application, if you do not
+specify a JIT stack, or if you assign or pass back NULL from a callback, that
+is thread-safe, because each thread has its own machine stack. However, if you
+assign or pass back a non-NULL JIT stack, this must be a different stack for
+each thread so that the application is thread-safe.
+.P
+Strictly speaking, even more is allowed. You can assign the same non-NULL stack
+to any number of patterns as long as they are not used for matching by multiple
+threads at the same time. For example, you can assign the same stack to all
+compiled patterns, and use a global mutex in the callback to wait until the
+stack is available for use. However, this is an inefficient solution, and not
+recommended.
+.P
+This is a suggestion for how a multithreaded program that needs to set up
+non-default JIT stacks might operate:
+.sp
+  During thread initalization
+    thread_local_var = pcre_jit_stack_alloc(...)
+.sp
+  During thread exit
+    pcre_jit_stack_free(thread_local_var)
+.sp
+  Use a one-line callback function
+    return thread_local_var
+.sp
+All the functions described in this section do nothing if JIT is not available,
+and \fBpcre_assign_jit_stack()\fP does nothing unless the \fBextra\fP argument
+is non-NULL and points to a \fBpcre_extra\fP block that is the result of a
+successful study with PCRE_STUDY_JIT_COMPILE etc.
+.
+.
+.\" HTML 
+.SH "JIT STACK FAQ"
+.rs
+.sp
+(1) Why do we need JIT stacks?
+.sp
+PCRE (and JIT) is a recursive, depth-first engine, so it needs a stack where
+the local data of the current node is pushed before checking its child nodes.
+Allocating real machine stack on some platforms is difficult. For example, the
+stack chain needs to be updated every time if we extend the stack on PowerPC.
+Although it is possible, its updating time overhead decreases performance. So
+we do the recursion in memory.
+.P
+(2) Why don't we simply allocate blocks of memory with \fBmalloc()\fP?
+.sp
+Modern operating systems have a nice feature: they can reserve an address space
+instead of allocating memory. We can safely allocate memory pages inside this
+address space, so the stack could grow without moving memory data (this is
+important because of pointers). Thus we can allocate 1M address space, and use
+only a single memory page (usually 4K) if that is enough. However, we can still
+grow up to 1M anytime if needed.
+.P
+(3) Who "owns" a JIT stack?
+.sp
+The owner of the stack is the user program, not the JIT studied pattern or
+anything else. The user program must ensure that if a stack is used by
+\fBpcre_exec()\fP, (that is, it is assigned to the pattern currently running),
+that stack must not be used by any other threads (to avoid overwriting the same
+memory area). The best practice for multithreaded programs is to allocate a
+stack for each thread, and return this stack through the JIT callback function.
+.P
+(4) When should a JIT stack be freed?
+.sp
+You can free a JIT stack at any time, as long as it will not be used by
+\fBpcre_exec()\fP again. When you assign the stack to a pattern, only a pointer
+is set. There is no reference counting or any other magic. You can free the
+patterns and stacks in any order, anytime. Just \fIdo not\fP call
+\fBpcre_exec()\fP with a pattern pointing to an already freed stack, as that
+will cause SEGFAULT. (Also, do not free a stack currently used by
+\fBpcre_exec()\fP in another thread). You can also replace the stack for a
+pattern at any time. You can even free the previous stack before assigning a
+replacement.
+.P
+(5) Should I allocate/free a stack every time before/after calling
+\fBpcre_exec()\fP?
+.sp
+No, because this is too costly in terms of resources. However, you could
+implement some clever idea which release the stack if it is not used in let's
+say two minutes. The JIT callback can help to achieve this without keeping a
+list of the currently JIT studied patterns.
+.P
+(6) OK, the stack is for long term memory allocation. But what happens if a
+pattern causes stack overflow with a stack of 1M? Is that 1M kept until the
+stack is freed?
+.sp
+Especially on embedded sytems, it might be a good idea to release memory
+sometimes without freeing the stack. There is no API for this at the moment.
+Probably a function call which returns with the currently allocated memory for
+any stack and another which allows releasing memory (shrinking the stack) would
+be a good idea if someone needs this.
+.P
+(7) This is too much of a headache. Isn't there any better solution for JIT
+stack handling?
+.sp
+No, thanks to Windows. If POSIX threads were used everywhere, we could throw
+out this complicated API.
+.
+.
+.SH "EXAMPLE CODE"
+.rs
+.sp
+This is a single-threaded example that specifies a JIT stack without using a
+callback.
+.sp
+  int rc;
+  int ovector[30];
+  pcre *re;
+  pcre_extra *extra;
+  pcre_jit_stack *jit_stack;
+.sp
+  re = pcre_compile(pattern, 0, &error, &erroffset, NULL);
+  /* Check for errors */
+  extra = pcre_study(re, PCRE_STUDY_JIT_COMPILE, &error);
+  jit_stack = pcre_jit_stack_alloc(32*1024, 512*1024);
+  /* Check for error (NULL) */
+  pcre_assign_jit_stack(extra, NULL, jit_stack);
+  rc = pcre_exec(re, extra, subject, length, 0, 0, ovector, 30);
+  /* Check results */
+  pcre_free(re);
+  pcre_free_study(extra);
+  pcre_jit_stack_free(jit_stack);
+.sp
+.
+.
+.SH "JIT FAST PATH API"
+.rs
+.sp
+Because the API described above falls back to interpreted execution when JIT is
+not available, it is convenient for programs that are written for general use
+in many environments. However, calling JIT via \fBpcre_exec()\fP does have a
+performance impact. Programs that are written for use where JIT is known to be
+available, and which need the best possible performance, can instead use a
+"fast path" API to call JIT execution directly instead of calling
+\fBpcre_exec()\fP (obviously only for patterns that have been successfully
+studied by JIT).
+.P
+The fast path function is called \fBpcre_jit_exec()\fP, and it takes exactly
+the same arguments as \fBpcre_exec()\fP, plus one additional argument that
+must point to a JIT stack. The JIT stack arrangements described above do not
+apply. The return values are the same as for \fBpcre_exec()\fP.
+.P
+When you call \fBpcre_exec()\fP, as well as testing for invalid options, a
+number of other sanity checks are performed on the arguments. For example, if
+the subject pointer is NULL, or its length is negative, an immediate error is
+given. Also, unless PCRE_NO_UTF[8|16|32] is set, a UTF subject string is tested
+for validity. In the interests of speed, these checks do not happen on the JIT
+fast path, and if invalid data is passed, the result is undefined.
+.P
+Bypassing the sanity checks and the \fBpcre_exec()\fP wrapping can give
+speedups of more than 10%.
+.
+.
+.SH "SEE ALSO"
+.rs
+.sp
+\fBpcreapi\fP(3)
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel (FAQ by Zoltan Herczeg)
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 17 March 2013
+Copyright (c) 1997-2013 University of Cambridge.
+.fi
diff --git a/doc/pcrelimits.3 b/doc/pcrelimits.3
new file mode 100644
index 0000000..423d6a2
--- /dev/null
+++ b/doc/pcrelimits.3
@@ -0,0 +1,71 @@
+.TH PCRELIMITS 3 "05 November 2013" "PCRE 8.34"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "SIZE AND OTHER LIMITATIONS"
+.rs
+.sp
+There are some size limitations in PCRE but it is hoped that they will never in
+practice be relevant.
+.P
+The maximum length of a compiled pattern is approximately 64K data units (bytes
+for the 8-bit library, 16-bit units for the 16-bit library, and 32-bit units for
+the 32-bit library) if PCRE is compiled with the default internal linkage size,
+which is 2 bytes for the 8-bit and 16-bit libraries, and 4 bytes for the 32-bit
+library. If you want to process regular expressions that are truly enormous,
+you can compile PCRE with an internal linkage size of 3 or 4 (when building the
+16-bit or 32-bit library, 3 is rounded up to 4). See the \fBREADME\fP file in
+the source distribution and the
+.\" HREF
+\fBpcrebuild\fP
+.\"
+documentation for details. In these cases the limit is substantially larger.
+However, the speed of execution is slower.
+.P
+All values in repeating quantifiers must be less than 65536.
+.P
+There is no limit to the number of parenthesized subpatterns, but there can be
+no more than 65535 capturing subpatterns. There is, however, a limit to the
+depth of nesting of parenthesized subpatterns of all kinds. This is imposed in
+order to limit the amount of system stack used at compile time. The limit can
+be specified when PCRE is built; the default is 250.
+.P
+There is a limit to the number of forward references to subsequent subpatterns
+of around 200,000. Repeated forward references with fixed upper limits, for
+example, (?2){0,100} when subpattern number 2 is to the right, are included in
+the count. There is no limit to the number of backward references.
+.P
+The maximum length of name for a named subpattern is 32 characters, and the
+maximum number of named subpatterns is 10000.
+.P
+The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb
+is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit libraries.
+.P
+The maximum length of a subject string is the largest positive number that an
+integer variable can hold. However, when using the traditional matching
+function, PCRE uses recursion to handle subpatterns and indefinite repetition.
+This means that the available stack space may limit the size of a subject
+string that can be processed by certain patterns. For a discussion of stack
+issues, see the
+.\" HREF
+\fBpcrestack\fP
+.\"
+documentation.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 05 November 2013
+Copyright (c) 1997-2013 University of Cambridge.
+.fi
diff --git a/doc/pcrematching.3 b/doc/pcrematching.3
new file mode 100644
index 0000000..268baf9
--- /dev/null
+++ b/doc/pcrematching.3
@@ -0,0 +1,214 @@
+.TH PCREMATCHING 3 "12 November 2013" "PCRE 8.34"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "PCRE MATCHING ALGORITHMS"
+.rs
+.sp
+This document describes the two different algorithms that are available in PCRE
+for matching a compiled regular expression against a given subject string. The
+"standard" algorithm is the one provided by the \fBpcre_exec()\fP,
+\fBpcre16_exec()\fP and \fBpcre32_exec()\fP functions. These work in the same
+as as Perl's matching function, and provide a Perl-compatible matching operation.
+The just-in-time (JIT) optimization that is described in the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation is compatible with these functions.
+.P
+An alternative algorithm is provided by the \fBpcre_dfa_exec()\fP,
+\fBpcre16_dfa_exec()\fP and \fBpcre32_dfa_exec()\fP functions; they operate in
+a different way, and are not Perl-compatible. This alternative has advantages
+and disadvantages compared with the standard algorithm, and these are described
+below.
+.P
+When there is only one possible way in which a given subject string can match a
+pattern, the two algorithms give the same answer. A difference arises, however,
+when there are multiple possibilities. For example, if the pattern
+.sp
+  ^<.*>
+.sp
+is matched against the string
+.sp
+    
+.sp
+there are three possible answers. The standard algorithm finds only one of
+them, whereas the alternative algorithm finds all three.
+.
+.
+.SH "REGULAR EXPRESSIONS AS TREES"
+.rs
+.sp
+The set of strings that are matched by a regular expression can be represented
+as a tree structure. An unlimited repetition in the pattern makes the tree of
+infinite size, but it is still a tree. Matching the pattern to a given subject
+string (from a given starting point) can be thought of as a search of the tree.
+There are two ways to search a tree: depth-first and breadth-first, and these
+correspond to the two matching algorithms provided by PCRE.
+.
+.
+.SH "THE STANDARD MATCHING ALGORITHM"
+.rs
+.sp
+In the terminology of Jeffrey Friedl's book "Mastering Regular
+Expressions", the standard algorithm is an "NFA algorithm". It conducts a
+depth-first search of the pattern tree. That is, it proceeds along a single
+path through the tree, checking that the subject matches what is required. When
+there is a mismatch, the algorithm tries any alternatives at the current point,
+and if they all fail, it backs up to the previous branch point in the tree, and
+tries the next alternative branch at that level. This often involves backing up
+(moving to the left) in the subject string as well. The order in which
+repetition branches are tried is controlled by the greedy or ungreedy nature of
+the quantifier.
+.P
+If a leaf node is reached, a matching string has been found, and at that point
+the algorithm stops. Thus, if there is more than one possible match, this
+algorithm returns the first one that it finds. Whether this is the shortest,
+the longest, or some intermediate length depends on the way the greedy and
+ungreedy repetition quantifiers are specified in the pattern.
+.P
+Because it ends up with a single path through the tree, it is relatively
+straightforward for this algorithm to keep track of the substrings that are
+matched by portions of the pattern in parentheses. This provides support for
+capturing parentheses and back references.
+.
+.
+.SH "THE ALTERNATIVE MATCHING ALGORITHM"
+.rs
+.sp
+This algorithm conducts a breadth-first search of the tree. Starting from the
+first matching point in the subject, it scans the subject string from left to
+right, once, character by character, and as it does this, it remembers all the
+paths through the tree that represent valid matches. In Friedl's terminology,
+this is a kind of "DFA algorithm", though it is not implemented as a
+traditional finite state machine (it keeps multiple states active
+simultaneously).
+.P
+Although the general principle of this matching algorithm is that it scans the
+subject string only once, without backtracking, there is one exception: when a
+lookaround assertion is encountered, the characters following or preceding the
+current point have to be independently inspected.
+.P
+The scan continues until either the end of the subject is reached, or there are
+no more unterminated paths. At this point, terminated paths represent the
+different matching possibilities (if there are none, the match has failed).
+Thus, if there is more than one possible match, this algorithm finds all of
+them, and in particular, it finds the longest. The matches are returned in
+decreasing order of length. There is an option to stop the algorithm after the
+first match (which is necessarily the shortest) is found.
+.P
+Note that all the matches that are found start at the same point in the
+subject. If the pattern
+.sp
+  cat(er(pillar)?)?
+.sp
+is matched against the string "the caterpillar catchment", the result will be
+the three strings "caterpillar", "cater", and "cat" that start at the fifth
+character of the subject. The algorithm does not automatically move on to find
+matches that start at later positions.
+.P
+PCRE's "auto-possessification" optimization usually applies to character
+repeats at the end of a pattern (as well as internally). For example, the
+pattern "a\ed+" is compiled as if it were "a\ed++" because there is no point
+even considering the possibility of backtracking into the repeated digits. For
+DFA matching, this means that only one possible match is found. If you really
+do want multiple matches in such cases, either use an ungreedy repeat
+("a\ed+?") or set the PCRE_NO_AUTO_POSSESS option when compiling.
+.P
+There are a number of features of PCRE regular expressions that are not
+supported by the alternative matching algorithm. They are as follows:
+.P
+1. Because the algorithm finds all possible matches, the greedy or ungreedy
+nature of repetition quantifiers is not relevant. Greedy and ungreedy
+quantifiers are treated in exactly the same way. However, possessive
+quantifiers can make a difference when what follows could also match what is
+quantified, for example in a pattern like this:
+.sp
+  ^a++\ew!
+.sp
+This pattern matches "aaab!" but not "aaa!", which would be matched by a
+non-possessive quantifier. Similarly, if an atomic group is present, it is
+matched as if it were a standalone pattern at the current point, and the
+longest match is then "locked in" for the rest of the overall pattern.
+.P
+2. When dealing with multiple paths through the tree simultaneously, it is not
+straightforward to keep track of captured substrings for the different matching
+possibilities, and PCRE's implementation of this algorithm does not attempt to
+do this. This means that no captured substrings are available.
+.P
+3. Because no substrings are captured, back references within the pattern are
+not supported, and cause errors if encountered.
+.P
+4. For the same reason, conditional expressions that use a backreference as the
+condition or test for a specific group recursion are not supported.
+.P
+5. Because many paths through the tree may be active, the \eK escape sequence,
+which resets the start of the match when encountered (but may be on some paths
+and not on others), is not supported. It causes an error if encountered.
+.P
+6. Callouts are supported, but the value of the \fIcapture_top\fP field is
+always 1, and the value of the \fIcapture_last\fP field is always -1.
+.P
+7. The \eC escape sequence, which (in the standard algorithm) always matches a
+single data unit, even in UTF-8, UTF-16 or UTF-32 modes, is not supported in
+these modes, because the alternative algorithm moves through the subject string
+one character (not data unit) at a time, for all active paths through the tree.
+.P
+8. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) are not
+supported. (*FAIL) is supported, and behaves like a failing negative assertion.
+.
+.
+.SH "ADVANTAGES OF THE ALTERNATIVE ALGORITHM"
+.rs
+.sp
+Using the alternative matching algorithm provides the following advantages:
+.P
+1. All possible matches (at a single point in the subject) are automatically
+found, and in particular, the longest match is found. To find more than one
+match using the standard algorithm, you have to do kludgy things with
+callouts.
+.P
+2. Because the alternative algorithm scans the subject string just once, and
+never needs to backtrack (except for lookbehinds), it is possible to pass very
+long subject strings to the matching function in several pieces, checking for
+partial matching each time. Although it is possible to do multi-segment
+matching using the standard algorithm by retaining partially matched
+substrings, it is more complicated. The
+.\" HREF
+\fBpcrepartial\fP
+.\"
+documentation gives details of partial matching and discusses multi-segment
+matching.
+.
+.
+.SH "DISADVANTAGES OF THE ALTERNATIVE ALGORITHM"
+.rs
+.sp
+The alternative algorithm suffers from a number of disadvantages:
+.P
+1. It is substantially slower than the standard algorithm. This is partly
+because it has to search for all possible matches, but is also because it is
+less susceptible to optimization.
+.P
+2. Capturing parentheses and back references are not supported.
+.P
+3. Although atomic groups are supported, their use does not provide the
+performance advantage that it does for the standard algorithm.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 12 November 2013
+Copyright (c) 1997-2012 University of Cambridge.
+.fi
diff --git a/doc/pcrepartial.3 b/doc/pcrepartial.3
new file mode 100644
index 0000000..14d0124
--- /dev/null
+++ b/doc/pcrepartial.3
@@ -0,0 +1,476 @@
+.TH PCREPARTIAL 3 "02 July 2013" "PCRE 8.34"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "PARTIAL MATCHING IN PCRE"
+.rs
+.sp
+In normal use of PCRE, if the subject string that is passed to a matching
+function matches as far as it goes, but is too short to match the entire
+pattern, PCRE_ERROR_NOMATCH is returned. There are circumstances where it might
+be helpful to distinguish this case from other cases in which there is no
+match.
+.P
+Consider, for example, an application where a human is required to type in data
+for a field with specific formatting requirements. An example might be a date
+in the form \fIddmmmyy\fP, defined by this pattern:
+.sp
+  ^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$
+.sp
+If the application sees the user's keystrokes one by one, and can check that
+what has been typed so far is potentially valid, it is able to raise an error
+as soon as a mistake is made, by beeping and not reflecting the character that
+has been typed, for example. This immediate feedback is likely to be a better
+user interface than a check that is delayed until the entire string has been
+entered. Partial matching can also be useful when the subject string is very
+long and is not all available at once.
+.P
+PCRE supports partial matching by means of the PCRE_PARTIAL_SOFT and
+PCRE_PARTIAL_HARD options, which can be set when calling any of the matching
+functions. For backwards compatibility, PCRE_PARTIAL is a synonym for
+PCRE_PARTIAL_SOFT. The essential difference between the two options is whether
+or not a partial match is preferred to an alternative complete match, though
+the details differ between the two types of matching function. If both options
+are set, PCRE_PARTIAL_HARD takes precedence.
+.P
+If you want to use partial matching with just-in-time optimized code, you must
+call \fBpcre_study()\fP, \fBpcre16_study()\fP or  \fBpcre32_study()\fP with one
+or both of these options:
+.sp
+  PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+  PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+.sp
+PCRE_STUDY_JIT_COMPILE should also be set if you are going to run non-partial
+matches on the same pattern. If the appropriate JIT study mode has not been set
+for a match, the interpretive matching code is used.
+.P
+Setting a partial matching option disables two of PCRE's standard
+optimizations. PCRE remembers the last literal data unit in a pattern, and
+abandons matching immediately if it is not present in the subject string. This
+optimization cannot be used for a subject string that might match only
+partially. If the pattern was studied, PCRE knows the minimum length of a
+matching string, and does not bother to run the matching function on shorter
+strings. This optimization is also disabled for partial matching.
+.
+.
+.SH "PARTIAL MATCHING USING pcre_exec() OR pcre[16|32]_exec()"
+.rs
+.sp
+A partial match occurs during a call to \fBpcre_exec()\fP or
+\fBpcre[16|32]_exec()\fP when the end of the subject string is reached
+successfully, but matching cannot continue because more characters are needed.
+However, at least one character in the subject must have been inspected. This
+character need not form part of the final matched string; lookbehind assertions
+and the \eK escape sequence provide ways of inspecting characters before the
+start of a matched substring. The requirement for inspecting at least one
+character exists because an empty string can always be matched; without such a
+restriction there would always be a partial match of an empty string at the end
+of the subject.
+.P
+If there are at least two slots in the offsets vector when a partial match is
+returned, the first slot is set to the offset of the earliest character that
+was inspected. For convenience, the second offset points to the end of the
+subject so that a substring can easily be identified. If there are at least
+three slots in the offsets vector, the third slot is set to the offset of the
+character where matching started.
+.P
+For the majority of patterns, the contents of the first and third slots will be
+the same. However, for patterns that contain lookbehind assertions, or begin
+with \eb or \eB, characters before the one where matching started may have been
+inspected while carrying out the match. For example, consider this pattern:
+.sp
+  /(?<=abc)123/
+.sp
+This pattern matches "123", but only if it is preceded by "abc". If the subject
+string is "xyzabc12", the first two offsets after a partial match are for the
+substring "abc12", because all these characters were inspected. However, the
+third offset is set to 6, because that is the offset where matching began.
+.P
+What happens when a partial match is identified depends on which of the two
+partial matching options are set.
+.
+.
+.SS "PCRE_PARTIAL_SOFT WITH pcre_exec() OR pcre[16|32]_exec()"
+.rs
+.sp
+If PCRE_PARTIAL_SOFT is set when \fBpcre_exec()\fP or \fBpcre[16|32]_exec()\fP
+identifies a partial match, the partial match is remembered, but matching
+continues as normal, and other alternatives in the pattern are tried. If no
+complete match can be found, PCRE_ERROR_PARTIAL is returned instead of
+PCRE_ERROR_NOMATCH.
+.P
+This option is "soft" because it prefers a complete match over a partial match.
+All the various matching items in a pattern behave as if the subject string is
+potentially complete. For example, \ez, \eZ, and $ match at the end of the
+subject, as normal, and for \eb and \eB the end of the subject is treated as a
+non-alphanumeric.
+.P
+If there is more than one partial match, the first one that was found provides
+the data that is returned. Consider this pattern:
+.sp
+  /123\ew+X|dogY/
+.sp
+If this is matched against the subject string "abc123dog", both
+alternatives fail to match, but the end of the subject is reached during
+matching, so PCRE_ERROR_PARTIAL is returned. The offsets are set to 3 and 9,
+identifying "123dog" as the first partial match that was found. (In this
+example, there are two partial matches, because "dog" on its own partially
+matches the second alternative.)
+.
+.
+.SS "PCRE_PARTIAL_HARD WITH pcre_exec() OR pcre[16|32]_exec()"
+.rs
+.sp
+If PCRE_PARTIAL_HARD is set for \fBpcre_exec()\fP or \fBpcre[16|32]_exec()\fP,
+PCRE_ERROR_PARTIAL is returned as soon as a partial match is found, without
+continuing to search for possible complete matches. This option is "hard"
+because it prefers an earlier partial match over a later complete match. For
+this reason, the assumption is made that the end of the supplied subject string
+may not be the true end of the available data, and so, if \ez, \eZ, \eb, \eB,
+or $ are encountered at the end of the subject, the result is
+PCRE_ERROR_PARTIAL, provided that at least one character in the subject has
+been inspected.
+.P
+Setting PCRE_PARTIAL_HARD also affects the way UTF-8 and UTF-16
+subject strings are checked for validity. Normally, an invalid sequence
+causes the error PCRE_ERROR_BADUTF8 or PCRE_ERROR_BADUTF16. However, in the
+special case of a truncated character at the end of the subject,
+PCRE_ERROR_SHORTUTF8 or PCRE_ERROR_SHORTUTF16 is returned when
+PCRE_PARTIAL_HARD is set.
+.
+.
+.SS "Comparing hard and soft partial matching"
+.rs
+.sp
+The difference between the two partial matching options can be illustrated by a
+pattern such as:
+.sp
+  /dog(sbody)?/
+.sp
+This matches either "dog" or "dogsbody", greedily (that is, it prefers the
+longer string if possible). If it is matched against the string "dog" with
+PCRE_PARTIAL_SOFT, it yields a complete match for "dog". However, if
+PCRE_PARTIAL_HARD is set, the result is PCRE_ERROR_PARTIAL. On the other hand,
+if the pattern is made ungreedy the result is different:
+.sp
+  /dog(sbody)??/
+.sp
+In this case the result is always a complete match because that is found first,
+and matching never continues after finding a complete match. It might be easier
+to follow this explanation by thinking of the two patterns like this:
+.sp
+  /dog(sbody)?/    is the same as  /dogsbody|dog/
+  /dog(sbody)??/   is the same as  /dog|dogsbody/
+.sp
+The second pattern will never match "dogsbody", because it will always find the
+shorter match first.
+.
+.
+.SH "PARTIAL MATCHING USING pcre_dfa_exec() OR pcre[16|32]_dfa_exec()"
+.rs
+.sp
+The DFA functions move along the subject string character by character, without
+backtracking, searching for all possible matches simultaneously. If the end of
+the subject is reached before the end of the pattern, there is the possibility
+of a partial match, again provided that at least one character has been
+inspected.
+.P
+When PCRE_PARTIAL_SOFT is set, PCRE_ERROR_PARTIAL is returned only if there
+have been no complete matches. Otherwise, the complete matches are returned.
+However, if PCRE_PARTIAL_HARD is set, a partial match takes precedence over any
+complete matches. The portion of the string that was inspected when the longest
+partial match was found is set as the first matching string, provided there are
+at least two slots in the offsets vector.
+.P
+Because the DFA functions always search for all possible matches, and there is
+no difference between greedy and ungreedy repetition, their behaviour is
+different from the standard functions when PCRE_PARTIAL_HARD is set. Consider
+the string "dog" matched against the ungreedy pattern shown above:
+.sp
+  /dog(sbody)??/
+.sp
+Whereas the standard functions stop as soon as they find the complete match for
+"dog", the DFA functions also find the partial match for "dogsbody", and so
+return that when PCRE_PARTIAL_HARD is set.
+.
+.
+.SH "PARTIAL MATCHING AND WORD BOUNDARIES"
+.rs
+.sp
+If a pattern ends with one of sequences \eb or \eB, which test for word
+boundaries, partial matching with PCRE_PARTIAL_SOFT can give counter-intuitive
+results. Consider this pattern:
+.sp
+  /\ebcat\eb/
+.sp
+This matches "cat", provided there is a word boundary at either end. If the
+subject string is "the cat", the comparison of the final "t" with a following
+character cannot take place, so a partial match is found. However, normal
+matching carries on, and \eb matches at the end of the subject when the last
+character is a letter, so a complete match is found. The result, therefore, is
+\fInot\fP PCRE_ERROR_PARTIAL. Using PCRE_PARTIAL_HARD in this case does yield
+PCRE_ERROR_PARTIAL, because then the partial match takes precedence.
+.
+.
+.SH "FORMERLY RESTRICTED PATTERNS"
+.rs
+.sp
+For releases of PCRE prior to 8.00, because of the way certain internal
+optimizations were implemented in the \fBpcre_exec()\fP function, the
+PCRE_PARTIAL option (predecessor of PCRE_PARTIAL_SOFT) could not be used with
+all patterns. From release 8.00 onwards, the restrictions no longer apply, and
+partial matching with can be requested for any pattern.
+.P
+Items that were formerly restricted were repeated single characters and
+repeated metasequences. If PCRE_PARTIAL was set for a pattern that did not
+conform to the restrictions, \fBpcre_exec()\fP returned the error code
+PCRE_ERROR_BADPARTIAL (-13). This error code is no longer in use. The
+PCRE_INFO_OKPARTIAL call to \fBpcre_fullinfo()\fP to find out if a compiled
+pattern can be used for partial matching now always returns 1.
+.
+.
+.SH "EXAMPLE OF PARTIAL MATCHING USING PCRETEST"
+.rs
+.sp
+If the escape sequence \eP is present in a \fBpcretest\fP data line, the
+PCRE_PARTIAL_SOFT option is used for the match. Here is a run of \fBpcretest\fP
+that uses the date example quoted above:
+.sp
+    re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
+  data> 25jun04\eP
+   0: 25jun04
+   1: jun
+  data> 25dec3\eP
+  Partial match: 23dec3
+  data> 3ju\eP
+  Partial match: 3ju
+  data> 3juj\eP
+  No match
+  data> j\eP
+  No match
+.sp
+The first data string is matched completely, so \fBpcretest\fP shows the
+matched substrings. The remaining four strings do not match the complete
+pattern, but the first two are partial matches. Similar output is obtained
+if DFA matching is used.
+.P
+If the escape sequence \eP is present more than once in a \fBpcretest\fP data
+line, the PCRE_PARTIAL_HARD option is set for the match.
+.
+.
+.SH "MULTI-SEGMENT MATCHING WITH pcre_dfa_exec() OR pcre[16|32]_dfa_exec()"
+.rs
+.sp
+When a partial match has been found using a DFA matching function, it is
+possible to continue the match by providing additional subject data and calling
+the function again with the same compiled regular expression, this time setting
+the PCRE_DFA_RESTART option. You must pass the same working space as before,
+because this is where details of the previous partial match are stored. Here is
+an example using \fBpcretest\fP, using the \eR escape sequence to set the
+PCRE_DFA_RESTART option (\eD specifies the use of the DFA matching function):
+.sp
+    re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
+  data> 23ja\eP\eD
+  Partial match: 23ja
+  data> n05\eR\eD
+   0: n05
+.sp
+The first call has "23ja" as the subject, and requests partial matching; the
+second call has "n05" as the subject for the continued (restarted) match.
+Notice that when the match is complete, only the last part is shown; PCRE does
+not retain the previously partially-matched string. It is up to the calling
+program to do that if it needs to.
+.P
+That means that, for an unanchored pattern, if a continued match fails, it is
+not possible to try again at a new starting point. All this facility is capable
+of doing is continuing with the previous match attempt. In the previous
+example, if the second set of data is "ug23" the result is no match, even
+though there would be a match for "aug23" if the entire string were given at
+once. Depending on the application, this may or may not be what you want.
+The only way to allow for starting again at the next character is to retain the
+matched part of the subject and try a new complete match.
+.P
+You can set the PCRE_PARTIAL_SOFT or PCRE_PARTIAL_HARD options with
+PCRE_DFA_RESTART to continue partial matching over multiple segments. This
+facility can be used to pass very long subject strings to the DFA matching
+functions.
+.
+.
+.SH "MULTI-SEGMENT MATCHING WITH pcre_exec() OR pcre[16|32]_exec()"
+.rs
+.sp
+From release 8.00, the standard matching functions can also be used to do
+multi-segment matching. Unlike the DFA functions, it is not possible to
+restart the previous match with a new segment of data. Instead, new data must
+be added to the previous subject string, and the entire match re-run, starting
+from the point where the partial match occurred. Earlier data can be discarded.
+.P
+It is best to use PCRE_PARTIAL_HARD in this situation, because it does not
+treat the end of a segment as the end of the subject when matching \ez, \eZ,
+\eb, \eB, and $. Consider an unanchored pattern that matches dates:
+.sp
+    re> /\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed/
+  data> The date is 23ja\eP\eP
+  Partial match: 23ja
+.sp
+At this stage, an application could discard the text preceding "23ja", add on
+text from the next segment, and call the matching function again. Unlike the
+DFA matching functions, the entire matching string must always be available,
+and the complete matching process occurs for each call, so more memory and more
+processing time is needed.
+.P
+\fBNote:\fP If the pattern contains lookbehind assertions, or \eK, or starts
+with \eb or \eB, the string that is returned for a partial match includes
+characters that precede the start of what would be returned for a complete
+match, because it contains all the characters that were inspected during the
+partial match.
+.
+.
+.SH "ISSUES WITH MULTI-SEGMENT MATCHING"
+.rs
+.sp
+Certain types of pattern may give problems with multi-segment matching,
+whichever matching function is used.
+.P
+1. If the pattern contains a test for the beginning of a line, you need to pass
+the PCRE_NOTBOL option when the subject string for any call does start at the
+beginning of a line. There is also a PCRE_NOTEOL option, but in practice when
+doing multi-segment matching you should be using PCRE_PARTIAL_HARD, which
+includes the effect of PCRE_NOTEOL.
+.P
+2. Lookbehind assertions that have already been obeyed are catered for in the
+offsets that are returned for a partial match. However a lookbehind assertion
+later in the pattern could require even earlier characters to be inspected. You
+can handle this case by using the PCRE_INFO_MAXLOOKBEHIND option of the
+\fBpcre_fullinfo()\fP or \fBpcre[16|32]_fullinfo()\fP functions to obtain the
+length of the longest lookbehind in the pattern. This length is given in
+characters, not bytes. If you always retain at least that many characters
+before the partially matched string, all should be well. (Of course, near the
+start of the subject, fewer characters may be present; in that case all
+characters should be retained.)
+.P
+From release 8.33, there is a more accurate way of deciding which characters to
+retain. Instead of subtracting the length of the longest lookbehind from the
+earliest inspected character (\fIoffsets[0]\fP), the match start position
+(\fIoffsets[2]\fP) should be used, and the next match attempt started at the
+\fIoffsets[2]\fP character by setting the \fIstartoffset\fP argument of
+\fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP.
+.P
+For example, if the pattern "(?<=123)abc" is partially
+matched against the string "xx123a", the three offset values returned are 2, 6,
+and 5. This indicates that the matching process that gave a partial match
+started at offset 5, but the characters "123a" were all inspected. The maximum
+lookbehind for that pattern is 3, so taking that away from 5 shows that we need
+only keep "123a", and the next match attempt can be started at offset 3 (that
+is, at "a") when further characters have been added. When the match start is
+not the earliest inspected character, \fBpcretest\fP shows it explicitly:
+.sp
+    re> "(?<=123)abc"
+  data> xx123a\eP\eP
+  Partial match at offset 5: 123a
+.P
+3. Because a partial match must always contain at least one character, what
+might be considered a partial match of an empty string actually gives a "no
+match" result. For example:
+.sp
+    re> /c(?<=abc)x/
+  data> ab\eP
+  No match
+.sp
+If the next segment begins "cx", a match should be found, but this will only
+happen if characters from the previous segment are retained. For this reason, a
+"no match" result should be interpreted as "partial match of an empty string"
+when the pattern contains lookbehinds.
+.P
+4. Matching a subject string that is split into multiple segments may not
+always produce exactly the same result as matching over one single long string,
+especially when PCRE_PARTIAL_SOFT is used. The section "Partial Matching and
+Word Boundaries" above describes an issue that arises if the pattern ends with
+\eb or \eB. Another kind of difference may occur when there are multiple
+matching possibilities, because (for PCRE_PARTIAL_SOFT) a partial match result
+is given only when there are no completed matches. This means that as soon as
+the shortest match has been found, continuation to a new subject segment is no
+longer possible. Consider again this \fBpcretest\fP example:
+.sp
+    re> /dog(sbody)?/
+  data> dogsb\eP
+   0: dog
+  data> do\eP\eD
+  Partial match: do
+  data> gsb\eR\eP\eD
+   0: g
+  data> dogsbody\eD
+   0: dogsbody
+   1: dog
+.sp
+The first data line passes the string "dogsb" to a standard matching function,
+setting the PCRE_PARTIAL_SOFT option. Although the string is a partial match
+for "dogsbody", the result is not PCRE_ERROR_PARTIAL, because the shorter
+string "dog" is a complete match. Similarly, when the subject is presented to
+a DFA matching function in several parts ("do" and "gsb" being the first two)
+the match stops when "dog" has been found, and it is not possible to continue.
+On the other hand, if "dogsbody" is presented as a single string, a DFA
+matching function finds both matches.
+.P
+Because of these problems, it is best to use PCRE_PARTIAL_HARD when matching
+multi-segment data. The example above then behaves differently:
+.sp
+    re> /dog(sbody)?/
+  data> dogsb\eP\eP
+  Partial match: dogsb
+  data> do\eP\eD
+  Partial match: do
+  data> gsb\eR\eP\eP\eD
+  Partial match: gsb
+.sp
+5. Patterns that contain alternatives at the top level which do not all start
+with the same pattern item may not work as expected when PCRE_DFA_RESTART is
+used. For example, consider this pattern:
+.sp
+  1234|3789
+.sp
+If the first part of the subject is "ABC123", a partial match of the first
+alternative is found at offset 3. There is no partial match for the second
+alternative, because such a match does not start at the same point in the
+subject string. Attempting to continue with the string "7890" does not yield a
+match because only those alternatives that match at one point in the subject
+are remembered. The problem arises because the start of the second alternative
+matches within the first alternative. There is no problem with anchored
+patterns or patterns such as:
+.sp
+  1234|ABCD
+.sp
+where no string can be a partial match for both alternatives. This is not a
+problem if a standard matching function is used, because the entire match has
+to be rerun each time:
+.sp
+    re> /1234|3789/
+  data> ABC123\eP\eP
+  Partial match: 123
+  data> 1237890
+   0: 3789
+.sp
+Of course, instead of using PCRE_DFA_RESTART, the same technique of re-running
+the entire match can also be used with the DFA matching functions. Another
+possibility is to work with two buffers. If a partial match at offset \fIn\fP
+in the first buffer is followed by "no match" when PCRE_DFA_RESTART is used on
+the second buffer, you can then try a new match starting at offset \fIn+1\fP in
+the first buffer.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 02 July 2013
+Copyright (c) 1997-2013 University of Cambridge.
+.fi
diff --git a/doc/pcrepattern.3 b/doc/pcrepattern.3
new file mode 100644
index 0000000..f1c45cd
--- /dev/null
+++ b/doc/pcrepattern.3
@@ -0,0 +1,3265 @@
+.TH PCREPATTERN 3 "08 January 2014" "PCRE 8.35"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "PCRE REGULAR EXPRESSION DETAILS"
+.rs
+.sp
+The syntax and semantics of the regular expressions that are supported by PCRE
+are described in detail below. There is a quick-reference syntax summary in the
+.\" HREF
+\fBpcresyntax\fP
+.\"
+page. PCRE tries to match Perl syntax and semantics as closely as it can. PCRE
+also supports some alternative regular expression syntax (which does not
+conflict with the Perl syntax) in order to provide some compatibility with
+regular expressions in Python, .NET, and Oniguruma.
+.P
+Perl's regular expressions are described in its own documentation, and
+regular expressions in general are covered in a number of books, some of which
+have copious examples. Jeffrey Friedl's "Mastering Regular Expressions",
+published by O'Reilly, covers regular expressions in great detail. This
+description of PCRE's regular expressions is intended as reference material.
+.P
+This document discusses the patterns that are supported by PCRE when one its
+main matching functions, \fBpcre_exec()\fP (8-bit) or \fBpcre[16|32]_exec()\fP
+(16- or 32-bit), is used. PCRE also has alternative matching functions,
+\fBpcre_dfa_exec()\fP and \fBpcre[16|32_dfa_exec()\fP, which match using a
+different algorithm that is not Perl-compatible. Some of the features discussed
+below are not available when DFA matching is used. The advantages and
+disadvantages of the alternative functions, and how they differ from the normal
+functions, are discussed in the
+.\" HREF
+\fBpcrematching\fP
+.\"
+page.
+.
+.
+.SH "SPECIAL START-OF-PATTERN ITEMS"
+.rs
+.sp
+A number of options that can be passed to \fBpcre_compile()\fP can also be set
+by special items at the start of a pattern. These are not Perl-compatible, but
+are provided to make these options accessible to pattern writers who are not
+able to change the program that processes the pattern. Any number of these
+items may appear, but they must all be together right at the start of the
+pattern string, and the letters must be in upper case.
+.
+.
+.SS "UTF support"
+.rs
+.sp
+The original operation of PCRE was on strings of one-byte characters. However,
+there is now also support for UTF-8 strings in the original library, an
+extra library that supports 16-bit and UTF-16 character strings, and a
+third library that supports 32-bit and UTF-32 character strings. To use these
+features, PCRE must be built to include appropriate support. When using UTF
+strings you must either call the compiling function with the PCRE_UTF8,
+PCRE_UTF16, or PCRE_UTF32 option, or the pattern must start with one of
+these special sequences:
+.sp
+  (*UTF8)
+  (*UTF16)
+  (*UTF32)
+  (*UTF)
+.sp
+(*UTF) is a generic sequence that can be used with any of the libraries.
+Starting a pattern with such a sequence is equivalent to setting the relevant
+option. How setting a UTF mode affects pattern matching is mentioned in several
+places below. There is also a summary of features in the
+.\" HREF
+\fBpcreunicode\fP
+.\"
+page.
+.P
+Some applications that allow their users to supply patterns may wish to
+restrict them to non-UTF data for security reasons. If the PCRE_NEVER_UTF
+option is set at compile time, (*UTF) etc. are not allowed, and their
+appearance causes an error.
+.
+.
+.SS "Unicode property support"
+.rs
+.sp
+Another special sequence that may appear at the start of a pattern is (*UCP).
+This has the same effect as setting the PCRE_UCP option: it causes sequences
+such as \ed and \ew to use Unicode properties to determine character types,
+instead of recognizing only characters with codes less than 128 via a lookup
+table.
+.
+.
+.SS "Disabling auto-possessification"
+.rs
+.sp
+If a pattern starts with (*NO_AUTO_POSSESS), it has the same effect as setting
+the PCRE_NO_AUTO_POSSESS option at compile time. This stops PCRE from making
+quantifiers possessive when what follows cannot match the repeated item. For
+example, by default a+b is treated as a++b. For more details, see the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation.
+.
+.
+.SS "Disabling start-up optimizations"
+.rs
+.sp
+If a pattern starts with (*NO_START_OPT), it has the same effect as setting the
+PCRE_NO_START_OPTIMIZE option either at compile or matching time. This disables
+several optimizations for quickly reaching "no match" results. For more
+details, see the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation.
+.
+.
+.\" HTML 
+.SS "Newline conventions"
+.rs
+.sp
+PCRE supports five different conventions for indicating line breaks in
+strings: a single CR (carriage return) character, a single LF (linefeed)
+character, the two-character sequence CRLF, any of the three preceding, or any
+Unicode newline sequence. The
+.\" HREF
+\fBpcreapi\fP
+.\"
+page has
+.\" HTML 
+.\" 
+further discussion
+.\"
+about newlines, and shows how to set the newline convention in the
+\fIoptions\fP arguments for the compiling and matching functions.
+.P
+It is also possible to specify a newline convention by starting a pattern
+string with one of the following five sequences:
+.sp
+  (*CR)        carriage return
+  (*LF)        linefeed
+  (*CRLF)      carriage return, followed by linefeed
+  (*ANYCRLF)   any of the three above
+  (*ANY)       all Unicode newline sequences
+.sp
+These override the default and the options given to the compiling function. For
+example, on a Unix system where LF is the default newline sequence, the pattern
+.sp
+  (*CR)a.b
+.sp
+changes the convention to CR. That pattern matches "a\enb" because LF is no
+longer a newline. If more than one of these settings is present, the last one
+is used.
+.P
+The newline convention affects where the circumflex and dollar assertions are
+true. It also affects the interpretation of the dot metacharacter when
+PCRE_DOTALL is not set, and the behaviour of \eN. However, it does not affect
+what the \eR escape sequence matches. By default, this is any Unicode newline
+sequence, for Perl compatibility. However, this can be changed; see the
+description of \eR in the section entitled
+.\" HTML 
+.\" 
+"Newline sequences"
+.\"
+below. A change of \eR setting can be combined with a change of newline
+convention.
+.
+.
+.SS "Setting match and recursion limits"
+.rs
+.sp
+The caller of \fBpcre_exec()\fP can set a limit on the number of times the
+internal \fBmatch()\fP function is called and on the maximum depth of
+recursive calls. These facilities are provided to catch runaway matches that
+are provoked by patterns with huge matching trees (a typical example is a
+pattern with nested unlimited repeats) and to avoid running out of system stack
+by too much recursion. When one of these limits is reached, \fBpcre_exec()\fP
+gives an error return. The limits can also be set by items at the start of the
+pattern of the form
+.sp
+  (*LIMIT_MATCH=d)
+  (*LIMIT_RECURSION=d)
+.sp
+where d is any number of decimal digits. However, the value of the setting must
+be less than the value set (or defaulted) by the caller of \fBpcre_exec()\fP
+for it to have any effect. In other words, the pattern writer can lower the
+limits set by the programmer, but not raise them. If there is more than one
+setting of one of these limits, the lower value is used.
+.
+.
+.SH "EBCDIC CHARACTER CODES"
+.rs
+.sp
+PCRE can be compiled to run in an environment that uses EBCDIC as its character
+code rather than ASCII or Unicode (typically a mainframe system). In the
+sections below, character code values are ASCII or Unicode; in an EBCDIC
+environment these characters may have different code values, and there are no
+code points greater than 255.
+.
+.
+.SH "CHARACTERS AND METACHARACTERS"
+.rs
+.sp
+A regular expression is a pattern that is matched against a subject string from
+left to right. Most characters stand for themselves in a pattern, and match the
+corresponding characters in the subject. As a trivial example, the pattern
+.sp
+  The quick brown fox
+.sp
+matches a portion of a subject string that is identical to itself. When
+caseless matching is specified (the PCRE_CASELESS option), letters are matched
+independently of case. In a UTF mode, PCRE always understands the concept of
+case for characters whose values are less than 128, so caseless matching is
+always possible. For characters with higher values, the concept of case is
+supported if PCRE is compiled with Unicode property support, but not otherwise.
+If you want to use caseless matching for characters 128 and above, you must
+ensure that PCRE is compiled with Unicode property support as well as with
+UTF support.
+.P
+The power of regular expressions comes from the ability to include alternatives
+and repetitions in the pattern. These are encoded in the pattern by the use of
+\fImetacharacters\fP, which do not stand for themselves but instead are
+interpreted in some special way.
+.P
+There are two different sets of metacharacters: those that are recognized
+anywhere in the pattern except within square brackets, and those that are
+recognized within square brackets. Outside square brackets, the metacharacters
+are as follows:
+.sp
+  \e      general escape character with several uses
+  ^      assert start of string (or line, in multiline mode)
+  $      assert end of string (or line, in multiline mode)
+  .      match any character except newline (by default)
+  [      start character class definition
+  |      start of alternative branch
+  (      start subpattern
+  )      end subpattern
+  ?      extends the meaning of (
+         also 0 or 1 quantifier
+         also quantifier minimizer
+  *      0 or more quantifier
+  +      1 or more quantifier
+         also "possessive quantifier"
+  {      start min/max quantifier
+.sp
+Part of a pattern that is in square brackets is called a "character class". In
+a character class the only metacharacters are:
+.sp
+  \e      general escape character
+  ^      negate the class, but only if the first character
+  -      indicates character range
+.\" JOIN
+  [      POSIX character class (only if followed by POSIX
+           syntax)
+  ]      terminates the character class
+.sp
+The following sections describe the use of each of the metacharacters.
+.
+.
+.SH BACKSLASH
+.rs
+.sp
+The backslash character has several uses. Firstly, if it is followed by a
+character that is not a number or a letter, it takes away any special meaning
+that character may have. This use of backslash as an escape character applies
+both inside and outside character classes.
+.P
+For example, if you want to match a * character, you write \e* in the pattern.
+This escaping action applies whether or not the following character would
+otherwise be interpreted as a metacharacter, so it is always safe to precede a
+non-alphanumeric with backslash to specify that it stands for itself. In
+particular, if you want to match a backslash, you write \e\e.
+.P
+In a UTF mode, only ASCII numbers and letters have any special meaning after a
+backslash. All other characters (in particular, those whose codepoints are
+greater than 127) are treated as literals.
+.P
+If a pattern is compiled with the PCRE_EXTENDED option, most white space in the
+pattern (other than in a character class), and characters between a # outside a
+character class and the next newline, inclusive, are ignored. An escaping
+backslash can be used to include a white space or # character as part of the
+pattern.
+.P
+If you want to remove the special meaning from a sequence of characters, you
+can do so by putting them between \eQ and \eE. This is different from Perl in
+that $ and @ are handled as literals in \eQ...\eE sequences in PCRE, whereas in
+Perl, $ and @ cause variable interpolation. Note the following examples:
+.sp
+  Pattern            PCRE matches   Perl matches
+.sp
+.\" JOIN
+  \eQabc$xyz\eE        abc$xyz        abc followed by the
+                                      contents of $xyz
+  \eQabc\e$xyz\eE       abc\e$xyz       abc\e$xyz
+  \eQabc\eE\e$\eQxyz\eE   abc$xyz        abc$xyz
+.sp
+The \eQ...\eE sequence is recognized both inside and outside character classes.
+An isolated \eE that is not preceded by \eQ is ignored. If \eQ is not followed
+by \eE later in the pattern, the literal interpretation continues to the end of
+the pattern (that is, \eE is assumed at the end). If the isolated \eQ is inside
+a character class, this causes an error, because the character class is not
+terminated.
+.
+.
+.\" HTML 
+.SS "Non-printing characters"
+.rs
+.sp
+A second use of backslash provides a way of encoding non-printing characters
+in patterns in a visible manner. There is no restriction on the appearance of
+non-printing characters, apart from the binary zero that terminates a pattern,
+but when a pattern is being prepared by text editing, it is often easier to use
+one of the following escape sequences than the binary character it represents:
+.sp
+  \ea        alarm, that is, the BEL character (hex 07)
+  \ecx       "control-x", where x is any ASCII character
+  \ee        escape (hex 1B)
+  \ef        form feed (hex 0C)
+  \en        linefeed (hex 0A)
+  \er        carriage return (hex 0D)
+  \et        tab (hex 09)
+  \e0dd      character with octal code 0dd
+  \eddd      character with octal code ddd, or back reference
+  \eo{ddd..} character with octal code ddd..
+  \exhh      character with hex code hh
+  \ex{hhh..} character with hex code hhh.. (non-JavaScript mode)
+  \euhhhh    character with hex code hhhh (JavaScript mode only)
+.sp
+The precise effect of \ecx on ASCII characters is as follows: if x is a lower
+case letter, it is converted to upper case. Then bit 6 of the character (hex
+40) is inverted. Thus \ecA to \ecZ become hex 01 to hex 1A (A is 41, Z is 5A),
+but \ec{ becomes hex 3B ({ is 7B), and \ec; becomes hex 7B (; is 3B). If the
+data item (byte or 16-bit value) following \ec has a value greater than 127, a
+compile-time error occurs. This locks out non-ASCII characters in all modes.
+.P
+The \ec facility was designed for use with ASCII characters, but with the
+extension to Unicode it is even less useful than it once was. It is, however,
+recognized when PCRE is compiled in EBCDIC mode, where data items are always
+bytes. In this mode, all values are valid after \ec. If the next character is a
+lower case letter, it is converted to upper case. Then the 0xc0 bits of the
+byte are inverted. Thus \ecA becomes hex 01, as in ASCII (A is C1), but because
+the EBCDIC letters are disjoint, \ecZ becomes hex 29 (Z is E9), and other
+characters also generate different values.
+.P
+After \e0 up to two further octal digits are read. If there are fewer than two
+digits, just those that are present are used. Thus the sequence \e0\ex\e07
+specifies two binary zeros followed by a BEL character (code value 7). Make
+sure you supply two digits after the initial zero if the pattern character that
+follows is itself an octal digit.
+.P
+The escape \eo must be followed by a sequence of octal digits, enclosed in
+braces. An error occurs if this is not the case. This escape is a recent
+addition to Perl; it provides way of specifying character code points as octal
+numbers greater than 0777, and it also allows octal numbers and back references
+to be unambiguously specified.
+.P
+For greater clarity and unambiguity, it is best to avoid following \e by a
+digit greater than zero. Instead, use \eo{} or \ex{} to specify character
+numbers, and \eg{} to specify back references. The following paragraphs
+describe the old, ambiguous syntax.
+.P
+The handling of a backslash followed by a digit other than 0 is complicated,
+and Perl has changed in recent releases, causing PCRE also to change. Outside a
+character class, PCRE reads the digit and any following digits as a decimal
+number. If the number is less than 8, or if there have been at least that many
+previous capturing left parentheses in the expression, the entire sequence is
+taken as a \fIback reference\fP. A description of how this works is given
+.\" HTML 
+.\" 
+later,
+.\"
+following the discussion of
+.\" HTML 
+.\" 
+parenthesized subpatterns.
+.\"
+.P
+Inside a character class, or if the decimal number following \e is greater than
+7 and there have not been that many capturing subpatterns, PCRE handles \e8 and
+\e9 as the literal characters "8" and "9", and otherwise re-reads up to three
+octal digits following the backslash, using them to generate a data character.
+Any subsequent digits stand for themselves. For example:
+.sp
+  \e040   is another way of writing an ASCII space
+.\" JOIN
+  \e40    is the same, provided there are fewer than 40
+            previous capturing subpatterns
+  \e7     is always a back reference
+.\" JOIN
+  \e11    might be a back reference, or another way of
+            writing a tab
+  \e011   is always a tab
+  \e0113  is a tab followed by the character "3"
+.\" JOIN
+  \e113   might be a back reference, otherwise the
+            character with octal code 113
+.\" JOIN
+  \e377   might be a back reference, otherwise
+            the value 255 (decimal)
+.\" JOIN
+  \e81    is either a back reference, or the two
+            characters "8" and "1"
+.sp
+Note that octal values of 100 or greater that are specified using this syntax
+must not be introduced by a leading zero, because no more than three octal
+digits are ever read.
+.P
+By default, after \ex that is not followed by {, from zero to two hexadecimal
+digits are read (letters can be in upper or lower case). Any number of
+hexadecimal digits may appear between \ex{ and }. If a character other than
+a hexadecimal digit appears between \ex{ and }, or if there is no terminating
+}, an error occurs.
+.P
+If the PCRE_JAVASCRIPT_COMPAT option is set, the interpretation of \ex is
+as just described only when it is followed by two hexadecimal digits.
+Otherwise, it matches a literal "x" character. In JavaScript mode, support for
+code points greater than 256 is provided by \eu, which must be followed by
+four hexadecimal digits; otherwise it matches a literal "u" character.
+.P
+Characters whose value is less than 256 can be defined by either of the two
+syntaxes for \ex (or by \eu in JavaScript mode). There is no difference in the
+way they are handled. For example, \exdc is exactly the same as \ex{dc} (or
+\eu00dc in JavaScript mode).
+.
+.
+.SS "Constraints on character values"
+.rs
+.sp
+Characters that are specified using octal or hexadecimal numbers are
+limited to certain values, as follows:
+.sp
+  8-bit non-UTF mode    less than 0x100
+  8-bit UTF-8 mode      less than 0x10ffff and a valid codepoint
+  16-bit non-UTF mode   less than 0x10000
+  16-bit UTF-16 mode    less than 0x10ffff and a valid codepoint
+  32-bit non-UTF mode   less than 0x100000000
+  32-bit UTF-32 mode    less than 0x10ffff and a valid codepoint
+.sp
+Invalid Unicode codepoints are the range 0xd800 to 0xdfff (the so-called
+"surrogate" codepoints), and 0xffef.
+.
+.
+.SS "Escape sequences in character classes"
+.rs
+.sp
+All the sequences that define a single character value can be used both inside
+and outside character classes. In addition, inside a character class, \eb is
+interpreted as the backspace character (hex 08).
+.P
+\eN is not allowed in a character class. \eB, \eR, and \eX are not special
+inside a character class. Like other unrecognized escape sequences, they are
+treated as the literal characters "B", "R", and "X" by default, but cause an
+error if the PCRE_EXTRA option is set. Outside a character class, these
+sequences have different meanings.
+.
+.
+.SS "Unsupported escape sequences"
+.rs
+.sp
+In Perl, the sequences \el, \eL, \eu, and \eU are recognized by its string
+handler and used to modify the case of following characters. By default, PCRE
+does not support these escape sequences. However, if the PCRE_JAVASCRIPT_COMPAT
+option is set, \eU matches a "U" character, and \eu can be used to define a
+character by code point, as described in the previous section.
+.
+.
+.SS "Absolute and relative back references"
+.rs
+.sp
+The sequence \eg followed by an unsigned or a negative number, optionally
+enclosed in braces, is an absolute or relative back reference. A named back
+reference can be coded as \eg{name}. Back references are discussed
+.\" HTML 
+.\" 
+later,
+.\"
+following the discussion of
+.\" HTML 
+.\" 
+parenthesized subpatterns.
+.\"
+.
+.
+.SS "Absolute and relative subroutine calls"
+.rs
+.sp
+For compatibility with Oniguruma, the non-Perl syntax \eg followed by a name or
+a number enclosed either in angle brackets or single quotes, is an alternative
+syntax for referencing a subpattern as a "subroutine". Details are discussed
+.\" HTML 
+.\" 
+later.
+.\"
+Note that \eg{...} (Perl syntax) and \eg<...> (Oniguruma syntax) are \fInot\fP
+synonymous. The former is a back reference; the latter is a
+.\" HTML 
+.\" 
+subroutine
+.\"
+call.
+.
+.
+.\" HTML 
+.SS "Generic character types"
+.rs
+.sp
+Another use of backslash is for specifying generic character types:
+.sp
+  \ed     any decimal digit
+  \eD     any character that is not a decimal digit
+  \eh     any horizontal white space character
+  \eH     any character that is not a horizontal white space character
+  \es     any white space character
+  \eS     any character that is not a white space character
+  \ev     any vertical white space character
+  \eV     any character that is not a vertical white space character
+  \ew     any "word" character
+  \eW     any "non-word" character
+.sp
+There is also the single sequence \eN, which matches a non-newline character.
+This is the same as
+.\" HTML 
+.\" 
+the "." metacharacter
+.\"
+when PCRE_DOTALL is not set. Perl also uses \eN to match characters by name;
+PCRE does not support this.
+.P
+Each pair of lower and upper case escape sequences partitions the complete set
+of characters into two disjoint sets. Any given character matches one, and only
+one, of each pair. The sequences can appear both inside and outside character
+classes. They each match one character of the appropriate type. If the current
+matching point is at the end of the subject string, all of them fail, because
+there is no character to match.
+.P
+For compatibility with Perl, \es did not used to match the VT character (code
+11), which made it different from the the POSIX "space" class. However, Perl
+added VT at release 5.18, and PCRE followed suit at release 8.34. The default
+\es characters are now HT (9), LF (10), VT (11), FF (12), CR (13), and space
+(32), which are defined as white space in the "C" locale. This list may vary if
+locale-specific matching is taking place. For example, in some locales the
+"non-breaking space" character (\exA0) is recognized as white space, and in
+others the VT character is not.
+.P
+A "word" character is an underscore or any character that is a letter or digit.
+By default, the definition of letters and digits is controlled by PCRE's
+low-valued character tables, and may vary if locale-specific matching is taking
+place (see
+.\" HTML 
+.\" 
+"Locale support"
+.\"
+in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page). For example, in a French locale such as "fr_FR" in Unix-like systems,
+or "french" in Windows, some character codes greater than 127 are used for
+accented letters, and these are then matched by \ew. The use of locales with
+Unicode is discouraged.
+.P
+By default, characters whose code points are greater than 127 never match \ed,
+\es, or \ew, and always match \eD, \eS, and \eW, although this may vary for
+characters in the range 128-255 when locale-specific matching is happening.
+These escape sequences retain their original meanings from before Unicode
+support was available, mainly for efficiency reasons. If PCRE is compiled with
+Unicode property support, and the PCRE_UCP option is set, the behaviour is
+changed so that Unicode properties are used to determine character types, as
+follows:
+.sp
+  \ed  any character that matches \ep{Nd} (decimal digit)
+  \es  any character that matches \ep{Z} or \eh or \ev
+  \ew  any character that matches \ep{L} or \ep{N}, plus underscore
+.sp
+The upper case escapes match the inverse sets of characters. Note that \ed
+matches only decimal digits, whereas \ew matches any Unicode digit, as well as
+any Unicode letter, and underscore. Note also that PCRE_UCP affects \eb, and
+\eB because they are defined in terms of \ew and \eW. Matching these sequences
+is noticeably slower when PCRE_UCP is set.
+.P
+The sequences \eh, \eH, \ev, and \eV are features that were added to Perl at
+release 5.10. In contrast to the other sequences, which match only ASCII
+characters by default, these always match certain high-valued code points,
+whether or not PCRE_UCP is set. The horizontal space characters are:
+.sp
+  U+0009     Horizontal tab (HT)
+  U+0020     Space
+  U+00A0     Non-break space
+  U+1680     Ogham space mark
+  U+180E     Mongolian vowel separator
+  U+2000     En quad
+  U+2001     Em quad
+  U+2002     En space
+  U+2003     Em space
+  U+2004     Three-per-em space
+  U+2005     Four-per-em space
+  U+2006     Six-per-em space
+  U+2007     Figure space
+  U+2008     Punctuation space
+  U+2009     Thin space
+  U+200A     Hair space
+  U+202F     Narrow no-break space
+  U+205F     Medium mathematical space
+  U+3000     Ideographic space
+.sp
+The vertical space characters are:
+.sp
+  U+000A     Linefeed (LF)
+  U+000B     Vertical tab (VT)
+  U+000C     Form feed (FF)
+  U+000D     Carriage return (CR)
+  U+0085     Next line (NEL)
+  U+2028     Line separator
+  U+2029     Paragraph separator
+.sp
+In 8-bit, non-UTF-8 mode, only the characters with codepoints less than 256 are
+relevant.
+.
+.
+.\" HTML 
+.SS "Newline sequences"
+.rs
+.sp
+Outside a character class, by default, the escape sequence \eR matches any
+Unicode newline sequence. In 8-bit non-UTF-8 mode \eR is equivalent to the
+following:
+.sp
+  (?>\er\en|\en|\ex0b|\ef|\er|\ex85)
+.sp
+This is an example of an "atomic group", details of which are given
+.\" HTML 
+.\" 
+below.
+.\"
+This particular group matches either the two-character sequence CR followed by
+LF, or one of the single characters LF (linefeed, U+000A), VT (vertical tab,
+U+000B), FF (form feed, U+000C), CR (carriage return, U+000D), or NEL (next
+line, U+0085). The two-character sequence is treated as a single unit that
+cannot be split.
+.P
+In other modes, two additional characters whose codepoints are greater than 255
+are added: LS (line separator, U+2028) and PS (paragraph separator, U+2029).
+Unicode character property support is not needed for these characters to be
+recognized.
+.P
+It is possible to restrict \eR to match only CR, LF, or CRLF (instead of the
+complete set of Unicode line endings) by setting the option PCRE_BSR_ANYCRLF
+either at compile time or when the pattern is matched. (BSR is an abbrevation
+for "backslash R".) This can be made the default when PCRE is built; if this is
+the case, the other behaviour can be requested via the PCRE_BSR_UNICODE option.
+It is also possible to specify these settings by starting a pattern string with
+one of the following sequences:
+.sp
+  (*BSR_ANYCRLF)   CR, LF, or CRLF only
+  (*BSR_UNICODE)   any Unicode newline sequence
+.sp
+These override the default and the options given to the compiling function, but
+they can themselves be overridden by options given to a matching function. Note
+that these special settings, which are not Perl-compatible, are recognized only
+at the very start of a pattern, and that they must be in upper case. If more
+than one of them is present, the last one is used. They can be combined with a
+change of newline convention; for example, a pattern can start with:
+.sp
+  (*ANY)(*BSR_ANYCRLF)
+.sp
+They can also be combined with the (*UTF8), (*UTF16), (*UTF32), (*UTF) or
+(*UCP) special sequences. Inside a character class, \eR is treated as an
+unrecognized escape sequence, and so matches the letter "R" by default, but
+causes an error if PCRE_EXTRA is set.
+.
+.
+.\" HTML 
+.SS Unicode character properties
+.rs
+.sp
+When PCRE is built with Unicode character property support, three additional
+escape sequences that match characters with specific properties are available.
+When in 8-bit non-UTF-8 mode, these sequences are of course limited to testing
+characters whose codepoints are less than 256, but they do work in this mode.
+The extra escape sequences are:
+.sp
+  \ep{\fIxx\fP}   a character with the \fIxx\fP property
+  \eP{\fIxx\fP}   a character without the \fIxx\fP property
+  \eX       a Unicode extended grapheme cluster
+.sp
+The property names represented by \fIxx\fP above are limited to the Unicode
+script names, the general category properties, "Any", which matches any
+character (including newline), and some special PCRE properties (described
+in the
+.\" HTML 
+.\" 
+next section).
+.\"
+Other Perl properties such as "InMusicalSymbols" are not currently supported by
+PCRE. Note that \eP{Any} does not match any characters, so always causes a
+match failure.
+.P
+Sets of Unicode characters are defined as belonging to certain scripts. A
+character from one of these sets can be matched using a script name. For
+example:
+.sp
+  \ep{Greek}
+  \eP{Han}
+.sp
+Those that are not part of an identified script are lumped together as
+"Common". The current list of scripts is:
+.P
+Arabic,
+Armenian,
+Avestan,
+Balinese,
+Bamum,
+Batak,
+Bengali,
+Bopomofo,
+Brahmi,
+Braille,
+Buginese,
+Buhid,
+Canadian_Aboriginal,
+Carian,
+Chakma,
+Cham,
+Cherokee,
+Common,
+Coptic,
+Cuneiform,
+Cypriot,
+Cyrillic,
+Deseret,
+Devanagari,
+Egyptian_Hieroglyphs,
+Ethiopic,
+Georgian,
+Glagolitic,
+Gothic,
+Greek,
+Gujarati,
+Gurmukhi,
+Han,
+Hangul,
+Hanunoo,
+Hebrew,
+Hiragana,
+Imperial_Aramaic,
+Inherited,
+Inscriptional_Pahlavi,
+Inscriptional_Parthian,
+Javanese,
+Kaithi,
+Kannada,
+Katakana,
+Kayah_Li,
+Kharoshthi,
+Khmer,
+Lao,
+Latin,
+Lepcha,
+Limbu,
+Linear_B,
+Lisu,
+Lycian,
+Lydian,
+Malayalam,
+Mandaic,
+Meetei_Mayek,
+Meroitic_Cursive,
+Meroitic_Hieroglyphs,
+Miao,
+Mongolian,
+Myanmar,
+New_Tai_Lue,
+Nko,
+Ogham,
+Old_Italic,
+Old_Persian,
+Old_South_Arabian,
+Old_Turkic,
+Ol_Chiki,
+Oriya,
+Osmanya,
+Phags_Pa,
+Phoenician,
+Rejang,
+Runic,
+Samaritan,
+Saurashtra,
+Sharada,
+Shavian,
+Sinhala,
+Sora_Sompeng,
+Sundanese,
+Syloti_Nagri,
+Syriac,
+Tagalog,
+Tagbanwa,
+Tai_Le,
+Tai_Tham,
+Tai_Viet,
+Takri,
+Tamil,
+Telugu,
+Thaana,
+Thai,
+Tibetan,
+Tifinagh,
+Ugaritic,
+Vai,
+Yi.
+.P
+Each character has exactly one Unicode general category property, specified by
+a two-letter abbreviation. For compatibility with Perl, negation can be
+specified by including a circumflex between the opening brace and the property
+name. For example, \ep{^Lu} is the same as \eP{Lu}.
+.P
+If only one letter is specified with \ep or \eP, it includes all the general
+category properties that start with that letter. In this case, in the absence
+of negation, the curly brackets in the escape sequence are optional; these two
+examples have the same effect:
+.sp
+  \ep{L}
+  \epL
+.sp
+The following general category property codes are supported:
+.sp
+  C     Other
+  Cc    Control
+  Cf    Format
+  Cn    Unassigned
+  Co    Private use
+  Cs    Surrogate
+.sp
+  L     Letter
+  Ll    Lower case letter
+  Lm    Modifier letter
+  Lo    Other letter
+  Lt    Title case letter
+  Lu    Upper case letter
+.sp
+  M     Mark
+  Mc    Spacing mark
+  Me    Enclosing mark
+  Mn    Non-spacing mark
+.sp
+  N     Number
+  Nd    Decimal number
+  Nl    Letter number
+  No    Other number
+.sp
+  P     Punctuation
+  Pc    Connector punctuation
+  Pd    Dash punctuation
+  Pe    Close punctuation
+  Pf    Final punctuation
+  Pi    Initial punctuation
+  Po    Other punctuation
+  Ps    Open punctuation
+.sp
+  S     Symbol
+  Sc    Currency symbol
+  Sk    Modifier symbol
+  Sm    Mathematical symbol
+  So    Other symbol
+.sp
+  Z     Separator
+  Zl    Line separator
+  Zp    Paragraph separator
+  Zs    Space separator
+.sp
+The special property L& is also supported: it matches a character that has
+the Lu, Ll, or Lt property, in other words, a letter that is not classified as
+a modifier or "other".
+.P
+The Cs (Surrogate) property applies only to characters in the range U+D800 to
+U+DFFF. Such characters are not valid in Unicode strings and so
+cannot be tested by PCRE, unless UTF validity checking has been turned off
+(see the discussion of PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK and
+PCRE_NO_UTF32_CHECK in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+page). Perl does not support the Cs property.
+.P
+The long synonyms for property names that Perl supports (such as \ep{Letter})
+are not supported by PCRE, nor is it permitted to prefix any of these
+properties with "Is".
+.P
+No character that is in the Unicode table has the Cn (unassigned) property.
+Instead, this property is assumed for any code point that is not in the
+Unicode table.
+.P
+Specifying caseless matching does not affect these escape sequences. For
+example, \ep{Lu} always matches only upper case letters. This is different from
+the behaviour of current versions of Perl.
+.P
+Matching characters by Unicode property is not fast, because PCRE has to do a
+multistage table lookup in order to find a character's property. That is why
+the traditional escape sequences such as \ed and \ew do not use Unicode
+properties in PCRE by default, though you can make them do so by setting the
+PCRE_UCP option or by starting the pattern with (*UCP).
+.
+.
+.SS Extended grapheme clusters
+.rs
+.sp
+The \eX escape matches any number of Unicode characters that form an "extended
+grapheme cluster", and treats the sequence as an atomic group
+.\" HTML 
+.\" 
+(see below).
+.\"
+Up to and including release 8.31, PCRE matched an earlier, simpler definition
+that was equivalent to
+.sp
+  (?>\ePM\epM*)
+.sp
+That is, it matched a character without the "mark" property, followed by zero
+or more characters with the "mark" property. Characters with the "mark"
+property are typically non-spacing accents that affect the preceding character.
+.P
+This simple definition was extended in Unicode to include more complicated
+kinds of composite character by giving each character a grapheme breaking
+property, and creating rules that use these properties to define the boundaries
+of extended grapheme clusters. In releases of PCRE later than 8.31, \eX matches
+one of these clusters.
+.P
+\eX always matches at least one character. Then it decides whether to add
+additional characters according to the following rules for ending a cluster:
+.P
+1. End at the end of the subject string.
+.P
+2. Do not end between CR and LF; otherwise end after any control character.
+.P
+3. Do not break Hangul (a Korean script) syllable sequences. Hangul characters
+are of five types: L, V, T, LV, and LVT. An L character may be followed by an
+L, V, LV, or LVT character; an LV or V character may be followed by a V or T
+character; an LVT or T character may be follwed only by a T character.
+.P
+4. Do not end before extending characters or spacing marks. Characters with
+the "mark" property always have the "extend" grapheme breaking property.
+.P
+5. Do not end after prepend characters.
+.P
+6. Otherwise, end the cluster.
+.
+.
+.\" HTML 
+.SS PCRE's additional properties
+.rs
+.sp
+As well as the standard Unicode properties described above, PCRE supports four
+more that make it possible to convert traditional escape sequences such as \ew
+and \es to use Unicode properties. PCRE uses these non-standard, non-Perl
+properties internally when PCRE_UCP is set. However, they may also be used
+explicitly. These properties are:
+.sp
+  Xan   Any alphanumeric character
+  Xps   Any POSIX space character
+  Xsp   Any Perl space character
+  Xwd   Any Perl "word" character
+.sp
+Xan matches characters that have either the L (letter) or the N (number)
+property. Xps matches the characters tab, linefeed, vertical tab, form feed, or
+carriage return, and any other character that has the Z (separator) property.
+Xsp is the same as Xps; it used to exclude vertical tab, for Perl
+compatibility, but Perl changed, and so PCRE followed at release 8.34. Xwd
+matches the same characters as Xan, plus underscore.
+.P
+There is another non-standard property, Xuc, which matches any character that
+can be represented by a Universal Character Name in C++ and other programming
+languages. These are the characters $, @, ` (grave accent), and all characters
+with Unicode code points greater than or equal to U+00A0, except for the
+surrogates U+D800 to U+DFFF. Note that most base (ASCII) characters are
+excluded. (Universal Character Names are of the form \euHHHH or \eUHHHHHHHH
+where H is a hexadecimal digit. Note that the Xuc property does not match these
+sequences but the characters that they represent.)
+.
+.
+.\" HTML 
+.SS "Resetting the match start"
+.rs
+.sp
+The escape sequence \eK causes any previously matched characters not to be
+included in the final matched sequence. For example, the pattern:
+.sp
+  foo\eKbar
+.sp
+matches "foobar", but reports that it has matched "bar". This feature is
+similar to a lookbehind assertion
+.\" HTML 
+.\" 
+(described below).
+.\"
+However, in this case, the part of the subject before the real match does not
+have to be of fixed length, as lookbehind assertions do. The use of \eK does
+not interfere with the setting of
+.\" HTML 
+.\" 
+captured substrings.
+.\"
+For example, when the pattern
+.sp
+  (foo)\eKbar
+.sp
+matches "foobar", the first substring is still set to "foo".
+.P
+Perl documents that the use of \eK within assertions is "not well defined". In
+PCRE, \eK is acted upon when it occurs inside positive assertions, but is
+ignored in negative assertions. Note that when a pattern such as (?=ab\eK)
+matches, the reported start of the match can be greater than the end of the
+match.
+.
+.
+.\" HTML 
+.SS "Simple assertions"
+.rs
+.sp
+The final use of backslash is for certain simple assertions. An assertion
+specifies a condition that has to be met at a particular point in a match,
+without consuming any characters from the subject string. The use of
+subpatterns for more complicated assertions is described
+.\" HTML 
+.\" 
+below.
+.\"
+The backslashed assertions are:
+.sp
+  \eb     matches at a word boundary
+  \eB     matches when not at a word boundary
+  \eA     matches at the start of the subject
+  \eZ     matches at the end of the subject
+          also matches before a newline at the end of the subject
+  \ez     matches only at the end of the subject
+  \eG     matches at the first matching position in the subject
+.sp
+Inside a character class, \eb has a different meaning; it matches the backspace
+character. If any other of these assertions appears in a character class, by
+default it matches the corresponding literal character (for example, \eB
+matches the letter B). However, if the PCRE_EXTRA option is set, an "invalid
+escape sequence" error is generated instead.
+.P
+A word boundary is a position in the subject string where the current character
+and the previous character do not both match \ew or \eW (i.e. one matches
+\ew and the other matches \eW), or the start or end of the string if the
+first or last character matches \ew, respectively. In a UTF mode, the meanings
+of \ew and \eW can be changed by setting the PCRE_UCP option. When this is
+done, it also affects \eb and \eB. Neither PCRE nor Perl has a separate "start
+of word" or "end of word" metasequence. However, whatever follows \eb normally
+determines which it is. For example, the fragment \eba matches "a" at the start
+of a word.
+.P
+The \eA, \eZ, and \ez assertions differ from the traditional circumflex and
+dollar (described in the next section) in that they only ever match at the very
+start and end of the subject string, whatever options are set. Thus, they are
+independent of multiline mode. These three assertions are not affected by the
+PCRE_NOTBOL or PCRE_NOTEOL options, which affect only the behaviour of the
+circumflex and dollar metacharacters. However, if the \fIstartoffset\fP
+argument of \fBpcre_exec()\fP is non-zero, indicating that matching is to start
+at a point other than the beginning of the subject, \eA can never match. The
+difference between \eZ and \ez is that \eZ matches before a newline at the end
+of the string as well as at the very end, whereas \ez matches only at the end.
+.P
+The \eG assertion is true only when the current matching position is at the
+start point of the match, as specified by the \fIstartoffset\fP argument of
+\fBpcre_exec()\fP. It differs from \eA when the value of \fIstartoffset\fP is
+non-zero. By calling \fBpcre_exec()\fP multiple times with appropriate
+arguments, you can mimic Perl's /g option, and it is in this kind of
+implementation where \eG can be useful.
+.P
+Note, however, that PCRE's interpretation of \eG, as the start of the current
+match, is subtly different from Perl's, which defines it as the end of the
+previous match. In Perl, these can be different when the previously matched
+string was empty. Because PCRE does just one match at a time, it cannot
+reproduce this behaviour.
+.P
+If all the alternatives of a pattern begin with \eG, the expression is anchored
+to the starting match position, and the "anchored" flag is set in the compiled
+regular expression.
+.
+.
+.SH "CIRCUMFLEX AND DOLLAR"
+.rs
+.sp
+The circumflex and dollar metacharacters are zero-width assertions. That is,
+they test for a particular condition being true without consuming any
+characters from the subject string.
+.P
+Outside a character class, in the default matching mode, the circumflex
+character is an assertion that is true only if the current matching point is at
+the start of the subject string. If the \fIstartoffset\fP argument of
+\fBpcre_exec()\fP is non-zero, circumflex can never match if the PCRE_MULTILINE
+option is unset. Inside a character class, circumflex has an entirely different
+meaning
+.\" HTML 
+.\" 
+(see below).
+.\"
+.P
+Circumflex need not be the first character of the pattern if a number of
+alternatives are involved, but it should be the first thing in each alternative
+in which it appears if the pattern is ever to match that branch. If all
+possible alternatives start with a circumflex, that is, if the pattern is
+constrained to match only at the start of the subject, it is said to be an
+"anchored" pattern. (There are also other constructs that can cause a pattern
+to be anchored.)
+.P
+The dollar character is an assertion that is true only if the current matching
+point is at the end of the subject string, or immediately before a newline at
+the end of the string (by default). Note, however, that it does not actually
+match the newline. Dollar need not be the last character of the pattern if a
+number of alternatives are involved, but it should be the last item in any
+branch in which it appears. Dollar has no special meaning in a character class.
+.P
+The meaning of dollar can be changed so that it matches only at the very end of
+the string, by setting the PCRE_DOLLAR_ENDONLY option at compile time. This
+does not affect the \eZ assertion.
+.P
+The meanings of the circumflex and dollar characters are changed if the
+PCRE_MULTILINE option is set. When this is the case, a circumflex matches
+immediately after internal newlines as well as at the start of the subject
+string. It does not match after a newline that ends the string. A dollar
+matches before any newlines in the string, as well as at the very end, when
+PCRE_MULTILINE is set. When newline is specified as the two-character
+sequence CRLF, isolated CR and LF characters do not indicate newlines.
+.P
+For example, the pattern /^abc$/ matches the subject string "def\enabc" (where
+\en represents a newline) in multiline mode, but not otherwise. Consequently,
+patterns that are anchored in single line mode because all branches start with
+^ are not anchored in multiline mode, and a match for circumflex is possible
+when the \fIstartoffset\fP argument of \fBpcre_exec()\fP is non-zero. The
+PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
+.P
+Note that the sequences \eA, \eZ, and \ez can be used to match the start and
+end of the subject in both modes, and if all branches of a pattern start with
+\eA it is always anchored, whether or not PCRE_MULTILINE is set.
+.
+.
+.\" HTML 
+.SH "FULL STOP (PERIOD, DOT) AND \eN"
+.rs
+.sp
+Outside a character class, a dot in the pattern matches any one character in
+the subject string except (by default) a character that signifies the end of a
+line.
+.P
+When a line ending is defined as a single character, dot never matches that
+character; when the two-character sequence CRLF is used, dot does not match CR
+if it is immediately followed by LF, but otherwise it matches all characters
+(including isolated CRs and LFs). When any Unicode line endings are being
+recognized, dot does not match CR or LF or any of the other line ending
+characters.
+.P
+The behaviour of dot with regard to newlines can be changed. If the PCRE_DOTALL
+option is set, a dot matches any one character, without exception. If the
+two-character sequence CRLF is present in the subject string, it takes two dots
+to match it.
+.P
+The handling of dot is entirely independent of the handling of circumflex and
+dollar, the only relationship being that they both involve newlines. Dot has no
+special meaning in a character class.
+.P
+The escape sequence \eN behaves like a dot, except that it is not affected by
+the PCRE_DOTALL option. In other words, it matches any character except one
+that signifies the end of a line. Perl also uses \eN to match characters by
+name; PCRE does not support this.
+.
+.
+.SH "MATCHING A SINGLE DATA UNIT"
+.rs
+.sp
+Outside a character class, the escape sequence \eC matches any one data unit,
+whether or not a UTF mode is set. In the 8-bit library, one data unit is one
+byte; in the 16-bit library it is a 16-bit unit; in the 32-bit library it is
+a 32-bit unit. Unlike a dot, \eC always
+matches line-ending characters. The feature is provided in Perl in order to
+match individual bytes in UTF-8 mode, but it is unclear how it can usefully be
+used. Because \eC breaks up characters into individual data units, matching one
+unit with \eC in a UTF mode means that the rest of the string may start with a
+malformed UTF character. This has undefined results, because PCRE assumes that
+it is dealing with valid UTF strings (and by default it checks this at the
+start of processing unless the PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK or
+PCRE_NO_UTF32_CHECK option is used).
+.P
+PCRE does not allow \eC to appear in lookbehind assertions
+.\" HTML 
+.\" 
+(described below)
+.\"
+in a UTF mode, because this would make it impossible to calculate the length of
+the lookbehind.
+.P
+In general, the \eC escape sequence is best avoided. However, one
+way of using it that avoids the problem of malformed UTF characters is to use a
+lookahead to check the length of the next character, as in this pattern, which
+could be used with a UTF-8 string (ignore white space and line breaks):
+.sp
+  (?| (?=[\ex00-\ex7f])(\eC) |
+      (?=[\ex80-\ex{7ff}])(\eC)(\eC) |
+      (?=[\ex{800}-\ex{ffff}])(\eC)(\eC)(\eC) |
+      (?=[\ex{10000}-\ex{1fffff}])(\eC)(\eC)(\eC)(\eC))
+.sp
+A group that starts with (?| resets the capturing parentheses numbers in each
+alternative (see
+.\" HTML 
+.\" 
+"Duplicate Subpattern Numbers"
+.\"
+below). The assertions at the start of each branch check the next UTF-8
+character for values whose encoding uses 1, 2, 3, or 4 bytes, respectively. The
+character's individual bytes are then captured by the appropriate number of
+groups.
+.
+.
+.\" HTML 
+.SH "SQUARE BRACKETS AND CHARACTER CLASSES"
+.rs
+.sp
+An opening square bracket introduces a character class, terminated by a closing
+square bracket. A closing square bracket on its own is not special by default.
+However, if the PCRE_JAVASCRIPT_COMPAT option is set, a lone closing square
+bracket causes a compile-time error. If a closing square bracket is required as
+a member of the class, it should be the first data character in the class
+(after an initial circumflex, if present) or escaped with a backslash.
+.P
+A character class matches a single character in the subject. In a UTF mode, the
+character may be more than one data unit long. A matched character must be in
+the set of characters defined by the class, unless the first character in the
+class definition is a circumflex, in which case the subject character must not
+be in the set defined by the class. If a circumflex is actually required as a
+member of the class, ensure it is not the first character, or escape it with a
+backslash.
+.P
+For example, the character class [aeiou] matches any lower case vowel, while
+[^aeiou] matches any character that is not a lower case vowel. Note that a
+circumflex is just a convenient notation for specifying the characters that
+are in the class by enumerating those that are not. A class that starts with a
+circumflex is not an assertion; it still consumes a character from the subject
+string, and therefore it fails if the current pointer is at the end of the
+string.
+.P
+In UTF-8 (UTF-16, UTF-32) mode, characters with values greater than 255 (0xffff)
+can be included in a class as a literal string of data units, or by using the
+\ex{ escaping mechanism.
+.P
+When caseless matching is set, any letters in a class represent both their
+upper case and lower case versions, so for example, a caseless [aeiou] matches
+"A" as well as "a", and a caseless [^aeiou] does not match "A", whereas a
+caseful version would. In a UTF mode, PCRE always understands the concept of
+case for characters whose values are less than 128, so caseless matching is
+always possible. For characters with higher values, the concept of case is
+supported if PCRE is compiled with Unicode property support, but not otherwise.
+If you want to use caseless matching in a UTF mode for characters 128 and
+above, you must ensure that PCRE is compiled with Unicode property support as
+well as with UTF support.
+.P
+Characters that might indicate line breaks are never treated in any special way
+when matching character classes, whatever line-ending sequence is in use, and
+whatever setting of the PCRE_DOTALL and PCRE_MULTILINE options is used. A class
+such as [^a] always matches one of these characters.
+.P
+The minus (hyphen) character can be used to specify a range of characters in a
+character class. For example, [d-m] matches any letter between d and m,
+inclusive. If a minus character is required in a class, it must be escaped with
+a backslash or appear in a position where it cannot be interpreted as
+indicating a range, typically as the first or last character in the class, or
+immediately after a range. For example, [b-d-z] matches letters in the range b
+to d, a hyphen character, or z.
+.P
+It is not possible to have the literal character "]" as the end character of a
+range. A pattern such as [W-]46] is interpreted as a class of two characters
+("W" and "-") followed by a literal string "46]", so it would match "W46]" or
+"-46]". However, if the "]" is escaped with a backslash it is interpreted as
+the end of range, so [W-\e]46] is interpreted as a class containing a range
+followed by two other characters. The octal or hexadecimal representation of
+"]" can also be used to end a range.
+.P
+An error is generated if a POSIX character class (see below) or an escape
+sequence other than one that defines a single character appears at a point
+where a range ending character is expected. For example, [z-\exff] is valid,
+but [A-\ed] and [A-[:digit:]] are not.
+.P
+Ranges operate in the collating sequence of character values. They can also be
+used for characters specified numerically, for example [\e000-\e037]. Ranges
+can include any characters that are valid for the current mode.
+.P
+If a range that includes letters is used when caseless matching is set, it
+matches the letters in either case. For example, [W-c] is equivalent to
+[][\e\e^_`wxyzabc], matched caselessly, and in a non-UTF mode, if character
+tables for a French locale are in use, [\exc8-\excb] matches accented E
+characters in both cases. In UTF modes, PCRE supports the concept of case for
+characters with values greater than 128 only when it is compiled with Unicode
+property support.
+.P
+The character escape sequences \ed, \eD, \eh, \eH, \ep, \eP, \es, \eS, \ev,
+\eV, \ew, and \eW may appear in a character class, and add the characters that
+they match to the class. For example, [\edABCDEF] matches any hexadecimal
+digit. In UTF modes, the PCRE_UCP option affects the meanings of \ed, \es, \ew
+and their upper case partners, just as it does when they appear outside a
+character class, as described in the section entitled
+.\" HTML 
+.\" 
+"Generic character types"
+.\"
+above. The escape sequence \eb has a different meaning inside a character
+class; it matches the backspace character. The sequences \eB, \eN, \eR, and \eX
+are not special inside a character class. Like any other unrecognized escape
+sequences, they are treated as the literal characters "B", "N", "R", and "X" by
+default, but cause an error if the PCRE_EXTRA option is set.
+.P
+A circumflex can conveniently be used with the upper case character types to
+specify a more restricted set of characters than the matching lower case type.
+For example, the class [^\eW_] matches any letter or digit, but not underscore,
+whereas [\ew] includes underscore. A positive character class should be read as
+"something OR something OR ..." and a negative class as "NOT something AND NOT
+something AND NOT ...".
+.P
+The only metacharacters that are recognized in character classes are backslash,
+hyphen (only where it can be interpreted as specifying a range), circumflex
+(only at the start), opening square bracket (only when it can be interpreted as
+introducing a POSIX class name, or for a special compatibility feature - see
+the next two sections), and the terminating closing square bracket. However,
+escaping other non-alphanumeric characters does no harm.
+.
+.
+.SH "POSIX CHARACTER CLASSES"
+.rs
+.sp
+Perl supports the POSIX notation for character classes. This uses names
+enclosed by [: and :] within the enclosing square brackets. PCRE also supports
+this notation. For example,
+.sp
+  [01[:alpha:]%]
+.sp
+matches "0", "1", any alphabetic character, or "%". The supported class names
+are:
+.sp
+  alnum    letters and digits
+  alpha    letters
+  ascii    character codes 0 - 127
+  blank    space or tab only
+  cntrl    control characters
+  digit    decimal digits (same as \ed)
+  graph    printing characters, excluding space
+  lower    lower case letters
+  print    printing characters, including space
+  punct    printing characters, excluding letters and digits and space
+  space    white space (the same as \es from PCRE 8.34)
+  upper    upper case letters
+  word     "word" characters (same as \ew)
+  xdigit   hexadecimal digits
+.sp
+The default "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13),
+and space (32). If locale-specific matching is taking place, the list of space
+characters may be different; there may be fewer or more of them. "Space" used
+to be different to \es, which did not include VT, for Perl compatibility.
+However, Perl changed at release 5.18, and PCRE followed at release 8.34.
+"Space" and \es now match the same set of characters.
+.P
+The name "word" is a Perl extension, and "blank" is a GNU extension from Perl
+5.8. Another Perl extension is negation, which is indicated by a ^ character
+after the colon. For example,
+.sp
+  [12[:^digit:]]
+.sp
+matches "1", "2", or any non-digit. PCRE (and Perl) also recognize the POSIX
+syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not
+supported, and an error is given if they are encountered.
+.P
+By default, characters with values greater than 128 do not match any of the
+POSIX character classes. However, if the PCRE_UCP option is passed to
+\fBpcre_compile()\fP, some of the classes are changed so that Unicode character
+properties are used. This is achieved by replacing certain POSIX classes by
+other sequences, as follows:
+.sp
+  [:alnum:]  becomes  \ep{Xan}
+  [:alpha:]  becomes  \ep{L}
+  [:blank:]  becomes  \eh
+  [:digit:]  becomes  \ep{Nd}
+  [:lower:]  becomes  \ep{Ll}
+  [:space:]  becomes  \ep{Xps}
+  [:upper:]  becomes  \ep{Lu}
+  [:word:]   becomes  \ep{Xwd}
+.sp
+Negated versions, such as [:^alpha:] use \eP instead of \ep. Three other POSIX
+classes are handled specially in UCP mode:
+.TP 10
+[:graph:]
+This matches characters that have glyphs that mark the page when printed. In
+Unicode property terms, it matches all characters with the L, M, N, P, S, or Cf
+properties, except for:
+.sp
+  U+061C           Arabic Letter Mark
+  U+180E           Mongolian Vowel Separator
+  U+2066 - U+2069  Various "isolate"s
+.sp
+.TP 10
+[:print:]
+This matches the same characters as [:graph:] plus space characters that are
+not controls, that is, characters with the Zs property.
+.TP 10
+[:punct:]
+This matches all characters that have the Unicode P (punctuation) property,
+plus those characters whose code points are less than 128 that have the S
+(Symbol) property.
+.P
+The other POSIX classes are unchanged, and match only characters with code
+points less than 128.
+.
+.
+.SH "COMPATIBILITY FEATURE FOR WORD BOUNDARIES"
+.rs
+.sp
+In the POSIX.2 compliant library that was included in 4.4BSD Unix, the ugly
+syntax [[:<:]] and [[:>:]] is used for matching "start of word" and "end of
+word". PCRE treats these items as follows:
+.sp
+  [[:<:]]  is converted to  \eb(?=\ew)
+  [[:>:]]  is converted to  \eb(?<=\ew)
+.sp
+Only these exact character sequences are recognized. A sequence such as
+[a[:<:]b] provokes error for an unrecognized POSIX class name. This support is
+not compatible with Perl. It is provided to help migrations from other
+environments, and is best not used in any new patterns. Note that \eb matches
+at the start and the end of a word (see
+.\" HTML 
+.\" 
+"Simple assertions"
+.\"
+above), and in a Perl-style pattern the preceding or following character
+normally shows which is wanted, without the need for the assertions that are
+used above in order to give exactly the POSIX behaviour.
+.
+.
+.SH "VERTICAL BAR"
+.rs
+.sp
+Vertical bar characters are used to separate alternative patterns. For example,
+the pattern
+.sp
+  gilbert|sullivan
+.sp
+matches either "gilbert" or "sullivan". Any number of alternatives may appear,
+and an empty alternative is permitted (matching the empty string). The matching
+process tries each alternative in turn, from left to right, and the first one
+that succeeds is used. If the alternatives are within a subpattern
+.\" HTML 
+.\" 
+(defined below),
+.\"
+"succeeds" means matching the rest of the main pattern as well as the
+alternative in the subpattern.
+.
+.
+.SH "INTERNAL OPTION SETTING"
+.rs
+.sp
+The settings of the PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and
+PCRE_EXTENDED options (which are Perl-compatible) can be changed from within
+the pattern by a sequence of Perl option letters enclosed between "(?" and ")".
+The option letters are
+.sp
+  i  for PCRE_CASELESS
+  m  for PCRE_MULTILINE
+  s  for PCRE_DOTALL
+  x  for PCRE_EXTENDED
+.sp
+For example, (?im) sets caseless, multiline matching. It is also possible to
+unset these options by preceding the letter with a hyphen, and a combined
+setting and unsetting such as (?im-sx), which sets PCRE_CASELESS and
+PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, is also
+permitted. If a letter appears both before and after the hyphen, the option is
+unset.
+.P
+The PCRE-specific options PCRE_DUPNAMES, PCRE_UNGREEDY, and PCRE_EXTRA can be
+changed in the same way as the Perl-compatible options by using the characters
+J, U and X respectively.
+.P
+When one of these option changes occurs at top level (that is, not inside
+subpattern parentheses), the change applies to the remainder of the pattern
+that follows. If the change is placed right at the start of a pattern, PCRE
+extracts it into the global options (and it will therefore show up in data
+extracted by the \fBpcre_fullinfo()\fP function).
+.P
+An option change within a subpattern (see below for a description of
+subpatterns) affects only that part of the subpattern that follows it, so
+.sp
+  (a(?i)b)c
+.sp
+matches abc and aBc and no other strings (assuming PCRE_CASELESS is not used).
+By this means, options can be made to have different settings in different
+parts of the pattern. Any changes made in one alternative do carry on
+into subsequent branches within the same subpattern. For example,
+.sp
+  (a(?i)b|c)
+.sp
+matches "ab", "aB", "c", and "C", even though when matching "C" the first
+branch is abandoned before the option setting. This is because the effects of
+option settings happen at compile time. There would be some very weird
+behaviour otherwise.
+.P
+\fBNote:\fP There are other PCRE-specific options that can be set by the
+application when the compiling or matching functions are called. In some cases
+the pattern can contain special leading sequences such as (*CRLF) to override
+what the application has set or what has been defaulted. Details are given in
+the section entitled
+.\" HTML 
+.\" 
+"Newline sequences"
+.\"
+above. There are also the (*UTF8), (*UTF16),(*UTF32), and (*UCP) leading
+sequences that can be used to set UTF and Unicode property modes; they are
+equivalent to setting the PCRE_UTF8, PCRE_UTF16, PCRE_UTF32 and the PCRE_UCP
+options, respectively. The (*UTF) sequence is a generic version that can be
+used with any of the libraries. However, the application can set the
+PCRE_NEVER_UTF option, which locks out the use of the (*UTF) sequences.
+.
+.
+.\" HTML 
+.SH SUBPATTERNS
+.rs
+.sp
+Subpatterns are delimited by parentheses (round brackets), which can be nested.
+Turning part of a pattern into a subpattern does two things:
+.sp
+1. It localizes a set of alternatives. For example, the pattern
+.sp
+  cat(aract|erpillar|)
+.sp
+matches "cataract", "caterpillar", or "cat". Without the parentheses, it would
+match "cataract", "erpillar" or an empty string.
+.sp
+2. It sets up the subpattern as a capturing subpattern. This means that, when
+the whole pattern matches, that portion of the subject string that matched the
+subpattern is passed back to the caller via the \fIovector\fP argument of the
+matching function. (This applies only to the traditional matching functions;
+the DFA matching functions do not support capturing.)
+.P
+Opening parentheses are counted from left to right (starting from 1) to obtain
+numbers for the capturing subpatterns. For example, if the string "the red
+king" is matched against the pattern
+.sp
+  the ((red|white) (king|queen))
+.sp
+the captured substrings are "red king", "red", and "king", and are numbered 1,
+2, and 3, respectively.
+.P
+The fact that plain parentheses fulfil two functions is not always helpful.
+There are often times when a grouping subpattern is required without a
+capturing requirement. If an opening parenthesis is followed by a question mark
+and a colon, the subpattern does not do any capturing, and is not counted when
+computing the number of any subsequent capturing subpatterns. For example, if
+the string "the white queen" is matched against the pattern
+.sp
+  the ((?:red|white) (king|queen))
+.sp
+the captured substrings are "white queen" and "queen", and are numbered 1 and
+2. The maximum number of capturing subpatterns is 65535.
+.P
+As a convenient shorthand, if any option settings are required at the start of
+a non-capturing subpattern, the option letters may appear between the "?" and
+the ":". Thus the two patterns
+.sp
+  (?i:saturday|sunday)
+  (?:(?i)saturday|sunday)
+.sp
+match exactly the same set of strings. Because alternative branches are tried
+from left to right, and options are not reset until the end of the subpattern
+is reached, an option setting in one branch does affect subsequent branches, so
+the above patterns match "SUNDAY" as well as "Saturday".
+.
+.
+.\" HTML 
+.SH "DUPLICATE SUBPATTERN NUMBERS"
+.rs
+.sp
+Perl 5.10 introduced a feature whereby each alternative in a subpattern uses
+the same numbers for its capturing parentheses. Such a subpattern starts with
+(?| and is itself a non-capturing subpattern. For example, consider this
+pattern:
+.sp
+  (?|(Sat)ur|(Sun))day
+.sp
+Because the two alternatives are inside a (?| group, both sets of capturing
+parentheses are numbered one. Thus, when the pattern matches, you can look
+at captured substring number one, whichever alternative matched. This construct
+is useful when you want to capture part, but not all, of one of a number of
+alternatives. Inside a (?| group, parentheses are numbered as usual, but the
+number is reset at the start of each branch. The numbers of any capturing
+parentheses that follow the subpattern start after the highest number used in
+any branch. The following example is taken from the Perl documentation. The
+numbers underneath show in which buffer the captured content will be stored.
+.sp
+  # before  ---------------branch-reset----------- after
+  / ( a )  (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
+  # 1            2         2  3        2     3     4
+.sp
+A back reference to a numbered subpattern uses the most recent value that is
+set for that number by any subpattern. The following pattern matches "abcabc"
+or "defdef":
+.sp
+  /(?|(abc)|(def))\e1/
+.sp
+In contrast, a subroutine call to a numbered subpattern always refers to the
+first one in the pattern with the given number. The following pattern matches
+"abcabc" or "defabc":
+.sp
+  /(?|(abc)|(def))(?1)/
+.sp
+If a
+.\" HTML 
+.\" 
+condition test
+.\"
+for a subpattern's having matched refers to a non-unique number, the test is
+true if any of the subpatterns of that number have matched.
+.P
+An alternative approach to using this "branch reset" feature is to use
+duplicate named subpatterns, as described in the next section.
+.
+.
+.SH "NAMED SUBPATTERNS"
+.rs
+.sp
+Identifying capturing parentheses by number is simple, but it can be very hard
+to keep track of the numbers in complicated regular expressions. Furthermore,
+if an expression is modified, the numbers may change. To help with this
+difficulty, PCRE supports the naming of subpatterns. This feature was not
+added to Perl until release 5.10. Python had the feature earlier, and PCRE
+introduced it at release 4.0, using the Python syntax. PCRE now supports both
+the Perl and the Python syntax. Perl allows identically numbered subpatterns to
+have different names, but PCRE does not.
+.P
+In PCRE, a subpattern can be named in one of three ways: (?...) or
+(?'name'...) as in Perl, or (?P...) as in Python. References to capturing
+parentheses from other parts of the pattern, such as
+.\" HTML 
+.\" 
+back references,
+.\"
+.\" HTML 
+.\" 
+recursion,
+.\"
+and
+.\" HTML 
+.\" 
+conditions,
+.\"
+can be made by name as well as by number.
+.P
+Names consist of up to 32 alphanumeric characters and underscores, but must
+start with a non-digit. Named capturing parentheses are still allocated numbers
+as well as names, exactly as if the names were not present. The PCRE API
+provides function calls for extracting the name-to-number translation table
+from a compiled pattern. There is also a convenience function for extracting a
+captured substring by name.
+.P
+By default, a name must be unique within a pattern, but it is possible to relax
+this constraint by setting the PCRE_DUPNAMES option at compile time. (Duplicate
+names are also always permitted for subpatterns with the same number, set up as
+described in the previous section.) Duplicate names can be useful for patterns
+where only one instance of the named parentheses can match. Suppose you want to
+match the name of a weekday, either as a 3-letter abbreviation or as the full
+name, and in both cases you want to extract the abbreviation. This pattern
+(ignoring the line breaks) does the job:
+.sp
+  (?Mon|Fri|Sun)(?:day)?|
+  (?Tue)(?:sday)?|
+  (?Wed)(?:nesday)?|
+  (?Thu)(?:rsday)?|
+  (?Sat)(?:urday)?
+.sp
+There are five capturing substrings, but only one is ever set after a match.
+(An alternative way of solving this problem is to use a "branch reset"
+subpattern, as described in the previous section.)
+.P
+The convenience function for extracting the data by name returns the substring
+for the first (and in this example, the only) subpattern of that name that
+matched. This saves searching to find which numbered subpattern it was.
+.P
+If you make a back reference to a non-unique named subpattern from elsewhere in
+the pattern, the subpatterns to which the name refers are checked in the order
+in which they appear in the overall pattern. The first one that is set is used
+for the reference. For example, this pattern matches both "foofoo" and
+"barbar" but not "foobar" or "barfoo":
+.sp
+  (?:(?foo)|(?bar))\ek
+.sp
+.P
+If you make a subroutine call to a non-unique named subpattern, the one that
+corresponds to the first occurrence of the name is used. In the absence of
+duplicate numbers (see the previous section) this is the one with the lowest
+number.
+.P
+If you use a named reference in a condition
+test (see the
+.\"
+.\" HTML 
+.\" 
+section about conditions
+.\"
+below), either to check whether a subpattern has matched, or to check for
+recursion, all subpatterns with the same name are tested. If the condition is
+true for any one of them, the overall condition is true. This is the same
+behaviour as testing by number. For further details of the interfaces for
+handling named subpatterns, see the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation.
+.P
+\fBWarning:\fP You cannot use different names to distinguish between two
+subpatterns with the same number because PCRE uses only the numbers when
+matching. For this reason, an error is given at compile time if different names
+are given to subpatterns with the same number. However, you can always give the
+same name to subpatterns with the same number, even when PCRE_DUPNAMES is not
+set.
+.
+.
+.SH REPETITION
+.rs
+.sp
+Repetition is specified by quantifiers, which can follow any of the following
+items:
+.sp
+  a literal data character
+  the dot metacharacter
+  the \eC escape sequence
+  the \eX escape sequence
+  the \eR escape sequence
+  an escape such as \ed or \epL that matches a single character
+  a character class
+  a back reference (see next section)
+  a parenthesized subpattern (including assertions)
+  a subroutine call to a subpattern (recursive or otherwise)
+.sp
+The general repetition quantifier specifies a minimum and maximum number of
+permitted matches, by giving the two numbers in curly brackets (braces),
+separated by a comma. The numbers must be less than 65536, and the first must
+be less than or equal to the second. For example:
+.sp
+  z{2,4}
+.sp
+matches "zz", "zzz", or "zzzz". A closing brace on its own is not a special
+character. If the second number is omitted, but the comma is present, there is
+no upper limit; if the second number and the comma are both omitted, the
+quantifier specifies an exact number of required matches. Thus
+.sp
+  [aeiou]{3,}
+.sp
+matches at least 3 successive vowels, but may match many more, while
+.sp
+  \ed{8}
+.sp
+matches exactly 8 digits. An opening curly bracket that appears in a position
+where a quantifier is not allowed, or one that does not match the syntax of a
+quantifier, is taken as a literal character. For example, {,6} is not a
+quantifier, but a literal string of four characters.
+.P
+In UTF modes, quantifiers apply to characters rather than to individual data
+units. Thus, for example, \ex{100}{2} matches two characters, each of
+which is represented by a two-byte sequence in a UTF-8 string. Similarly,
+\eX{3} matches three Unicode extended grapheme clusters, each of which may be
+several data units long (and they may be of different lengths).
+.P
+The quantifier {0} is permitted, causing the expression to behave as if the
+previous item and the quantifier were not present. This may be useful for
+subpatterns that are referenced as
+.\" HTML 
+.\" 
+subroutines
+.\"
+from elsewhere in the pattern (but see also the section entitled
+.\" HTML 
+.\" 
+"Defining subpatterns for use by reference only"
+.\"
+below). Items other than subpatterns that have a {0} quantifier are omitted
+from the compiled pattern.
+.P
+For convenience, the three most common quantifiers have single-character
+abbreviations:
+.sp
+  *    is equivalent to {0,}
+  +    is equivalent to {1,}
+  ?    is equivalent to {0,1}
+.sp
+It is possible to construct infinite loops by following a subpattern that can
+match no characters with a quantifier that has no upper limit, for example:
+.sp
+  (a?)*
+.sp
+Earlier versions of Perl and PCRE used to give an error at compile time for
+such patterns. However, because there are cases where this can be useful, such
+patterns are now accepted, but if any repetition of the subpattern does in fact
+match no characters, the loop is forcibly broken.
+.P
+By default, the quantifiers are "greedy", that is, they match as much as
+possible (up to the maximum number of permitted times), without causing the
+rest of the pattern to fail. The classic example of where this gives problems
+is in trying to match comments in C programs. These appear between /* and */
+and within the comment, individual * and / characters may appear. An attempt to
+match C comments by applying the pattern
+.sp
+  /\e*.*\e*/
+.sp
+to the string
+.sp
+  /* first comment */  not comment  /* second comment */
+.sp
+fails, because it matches the entire string owing to the greediness of the .*
+item.
+.P
+However, if a quantifier is followed by a question mark, it ceases to be
+greedy, and instead matches the minimum number of times possible, so the
+pattern
+.sp
+  /\e*.*?\e*/
+.sp
+does the right thing with the C comments. The meaning of the various
+quantifiers is not otherwise changed, just the preferred number of matches.
+Do not confuse this use of question mark with its use as a quantifier in its
+own right. Because it has two uses, it can sometimes appear doubled, as in
+.sp
+  \ed??\ed
+.sp
+which matches one digit by preference, but can match two if that is the only
+way the rest of the pattern matches.
+.P
+If the PCRE_UNGREEDY option is set (an option that is not available in Perl),
+the quantifiers are not greedy by default, but individual ones can be made
+greedy by following them with a question mark. In other words, it inverts the
+default behaviour.
+.P
+When a parenthesized subpattern is quantified with a minimum repeat count that
+is greater than 1 or with a limited maximum, more memory is required for the
+compiled pattern, in proportion to the size of the minimum or maximum.
+.P
+If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equivalent
+to Perl's /s) is set, thus allowing the dot to match newlines, the pattern is
+implicitly anchored, because whatever follows will be tried against every
+character position in the subject string, so there is no point in retrying the
+overall match at any position after the first. PCRE normally treats such a
+pattern as though it were preceded by \eA.
+.P
+In cases where it is known that the subject string contains no newlines, it is
+worth setting PCRE_DOTALL in order to obtain this optimization, or
+alternatively using ^ to indicate anchoring explicitly.
+.P
+However, there are some cases where the optimization cannot be used. When .*
+is inside capturing parentheses that are the subject of a back reference
+elsewhere in the pattern, a match at the start may fail where a later one
+succeeds. Consider, for example:
+.sp
+  (.*)abc\e1
+.sp
+If the subject is "xyz123abc123" the match point is the fourth character. For
+this reason, such a pattern is not implicitly anchored.
+.P
+Another case where implicit anchoring is not applied is when the leading .* is
+inside an atomic group. Once again, a match at the start may fail where a later
+one succeeds. Consider this pattern:
+.sp
+  (?>.*?a)b
+.sp
+It matches "ab" in the subject "aab". The use of the backtracking control verbs
+(*PRUNE) and (*SKIP) also disable this optimization.
+.P
+When a capturing subpattern is repeated, the value captured is the substring
+that matched the final iteration. For example, after
+.sp
+  (tweedle[dume]{3}\es*)+
+.sp
+has matched "tweedledum tweedledee" the value of the captured substring is
+"tweedledee". However, if there are nested capturing subpatterns, the
+corresponding captured values may have been set in previous iterations. For
+example, after
+.sp
+  /(a|(b))+/
+.sp
+matches "aba" the value of the second captured substring is "b".
+.
+.
+.\" HTML 
+.SH "ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS"
+.rs
+.sp
+With both maximizing ("greedy") and minimizing ("ungreedy" or "lazy")
+repetition, failure of what follows normally causes the repeated item to be
+re-evaluated to see if a different number of repeats allows the rest of the
+pattern to match. Sometimes it is useful to prevent this, either to change the
+nature of the match, or to cause it fail earlier than it otherwise might, when
+the author of the pattern knows there is no point in carrying on.
+.P
+Consider, for example, the pattern \ed+foo when applied to the subject line
+.sp
+  123456bar
+.sp
+After matching all 6 digits and then failing to match "foo", the normal
+action of the matcher is to try again with only 5 digits matching the \ed+
+item, and then with 4, and so on, before ultimately failing. "Atomic grouping"
+(a term taken from Jeffrey Friedl's book) provides the means for specifying
+that once a subpattern has matched, it is not to be re-evaluated in this way.
+.P
+If we use atomic grouping for the previous example, the matcher gives up
+immediately on failing to match "foo" the first time. The notation is a kind of
+special parenthesis, starting with (?> as in this example:
+.sp
+  (?>\ed+)foo
+.sp
+This kind of parenthesis "locks up" the  part of the pattern it contains once
+it has matched, and a failure further into the pattern is prevented from
+backtracking into it. Backtracking past it to previous items, however, works as
+normal.
+.P
+An alternative description is that a subpattern of this type matches the string
+of characters that an identical standalone pattern would match, if anchored at
+the current point in the subject string.
+.P
+Atomic grouping subpatterns are not capturing subpatterns. Simple cases such as
+the above example can be thought of as a maximizing repeat that must swallow
+everything it can. So, while both \ed+ and \ed+? are prepared to adjust the
+number of digits they match in order to make the rest of the pattern match,
+(?>\ed+) can only match an entire sequence of digits.
+.P
+Atomic groups in general can of course contain arbitrarily complicated
+subpatterns, and can be nested. However, when the subpattern for an atomic
+group is just a single repeated item, as in the example above, a simpler
+notation, called a "possessive quantifier" can be used. This consists of an
+additional + character following a quantifier. Using this notation, the
+previous example can be rewritten as
+.sp
+  \ed++foo
+.sp
+Note that a possessive quantifier can be used with an entire group, for
+example:
+.sp
+  (abc|xyz){2,3}+
+.sp
+Possessive quantifiers are always greedy; the setting of the PCRE_UNGREEDY
+option is ignored. They are a convenient notation for the simpler forms of
+atomic group. However, there is no difference in the meaning of a possessive
+quantifier and the equivalent atomic group, though there may be a performance
+difference; possessive quantifiers should be slightly faster.
+.P
+The possessive quantifier syntax is an extension to the Perl 5.8 syntax.
+Jeffrey Friedl originated the idea (and the name) in the first edition of his
+book. Mike McCloskey liked it, so implemented it when he built Sun's Java
+package, and PCRE copied it from there. It ultimately found its way into Perl
+at release 5.10.
+.P
+PCRE has an optimization that automatically "possessifies" certain simple
+pattern constructs. For example, the sequence A+B is treated as A++B because
+there is no point in backtracking into a sequence of A's when B must follow.
+.P
+When a pattern contains an unlimited repeat inside a subpattern that can itself
+be repeated an unlimited number of times, the use of an atomic group is the
+only way to avoid some failing matches taking a very long time indeed. The
+pattern
+.sp
+  (\eD+|<\ed+>)*[!?]
+.sp
+matches an unlimited number of substrings that either consist of non-digits, or
+digits enclosed in <>, followed by either ! or ?. When it matches, it runs
+quickly. However, if it is applied to
+.sp
+  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+.sp
+it takes a long time before reporting failure. This is because the string can
+be divided between the internal \eD+ repeat and the external * repeat in a
+large number of ways, and all have to be tried. (The example uses [!?] rather
+than a single character at the end, because both PCRE and Perl have an
+optimization that allows for fast failure when a single character is used. They
+remember the last single character that is required for a match, and fail early
+if it is not present in the string.) If the pattern is changed so that it uses
+an atomic group, like this:
+.sp
+  ((?>\eD+)|<\ed+>)*[!?]
+.sp
+sequences of non-digits cannot be broken, and failure happens quickly.
+.
+.
+.\" HTML 
+.SH "BACK REFERENCES"
+.rs
+.sp
+Outside a character class, a backslash followed by a digit greater than 0 (and
+possibly further digits) is a back reference to a capturing subpattern earlier
+(that is, to its left) in the pattern, provided there have been that many
+previous capturing left parentheses.
+.P
+However, if the decimal number following the backslash is less than 10, it is
+always taken as a back reference, and causes an error only if there are not
+that many capturing left parentheses in the entire pattern. In other words, the
+parentheses that are referenced need not be to the left of the reference for
+numbers less than 10. A "forward back reference" of this type can make sense
+when a repetition is involved and the subpattern to the right has participated
+in an earlier iteration.
+.P
+It is not possible to have a numerical "forward back reference" to a subpattern
+whose number is 10 or more using this syntax because a sequence such as \e50 is
+interpreted as a character defined in octal. See the subsection entitled
+"Non-printing characters"
+.\" HTML 
+.\" 
+above
+.\"
+for further details of the handling of digits following a backslash. There is
+no such problem when named parentheses are used. A back reference to any
+subpattern is possible using named parentheses (see below).
+.P
+Another way of avoiding the ambiguity inherent in the use of digits following a
+backslash is to use the \eg escape sequence. This escape must be followed by an
+unsigned number or a negative number, optionally enclosed in braces. These
+examples are all identical:
+.sp
+  (ring), \e1
+  (ring), \eg1
+  (ring), \eg{1}
+.sp
+An unsigned number specifies an absolute reference without the ambiguity that
+is present in the older syntax. It is also useful when literal digits follow
+the reference. A negative number is a relative reference. Consider this
+example:
+.sp
+  (abc(def)ghi)\eg{-1}
+.sp
+The sequence \eg{-1} is a reference to the most recently started capturing
+subpattern before \eg, that is, is it equivalent to \e2 in this example.
+Similarly, \eg{-2} would be equivalent to \e1. The use of relative references
+can be helpful in long patterns, and also in patterns that are created by
+joining together fragments that contain references within themselves.
+.P
+A back reference matches whatever actually matched the capturing subpattern in
+the current subject string, rather than anything matching the subpattern
+itself (see
+.\" HTML 
+.\" 
+"Subpatterns as subroutines"
+.\"
+below for a way of doing that). So the pattern
+.sp
+  (sens|respons)e and \e1ibility
+.sp
+matches "sense and sensibility" and "response and responsibility", but not
+"sense and responsibility". If caseful matching is in force at the time of the
+back reference, the case of letters is relevant. For example,
+.sp
+  ((?i)rah)\es+\e1
+.sp
+matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original
+capturing subpattern is matched caselessly.
+.P
+There are several different ways of writing back references to named
+subpatterns. The .NET syntax \ek{name} and the Perl syntax \ek or
+\ek'name' are supported, as is the Python syntax (?P=name). Perl 5.10's unified
+back reference syntax, in which \eg can be used for both numeric and named
+references, is also supported. We could rewrite the above example in any of
+the following ways:
+.sp
+  (?(?i)rah)\es+\ek
+  (?'p1'(?i)rah)\es+\ek{p1}
+  (?P(?i)rah)\es+(?P=p1)
+  (?(?i)rah)\es+\eg{p1}
+.sp
+A subpattern that is referenced by name may appear in the pattern before or
+after the reference.
+.P
+There may be more than one back reference to the same subpattern. If a
+subpattern has not actually been used in a particular match, any back
+references to it always fail by default. For example, the pattern
+.sp
+  (a|(bc))\e2
+.sp
+always fails if it starts to match "a" rather than "bc". However, if the
+PCRE_JAVASCRIPT_COMPAT option is set at compile time, a back reference to an
+unset value matches an empty string.
+.P
+Because there may be many capturing parentheses in a pattern, all digits
+following a backslash are taken as part of a potential back reference number.
+If the pattern continues with a digit character, some delimiter must be used to
+terminate the back reference. If the PCRE_EXTENDED option is set, this can be
+white space. Otherwise, the \eg{ syntax or an empty comment (see
+.\" HTML 
+.\" 
+"Comments"
+.\"
+below) can be used.
+.
+.SS "Recursive back references"
+.rs
+.sp
+A back reference that occurs inside the parentheses to which it refers fails
+when the subpattern is first used, so, for example, (a\e1) never matches.
+However, such references can be useful inside repeated subpatterns. For
+example, the pattern
+.sp
+  (a|b\e1)+
+.sp
+matches any number of "a"s and also "aba", "ababbaa" etc. At each iteration of
+the subpattern, the back reference matches the character string corresponding
+to the previous iteration. In order for this to work, the pattern must be such
+that the first iteration does not need to match the back reference. This can be
+done using alternation, as in the example above, or by a quantifier with a
+minimum of zero.
+.P
+Back references of this type cause the group that they reference to be treated
+as an
+.\" HTML 
+.\" 
+atomic group.
+.\"
+Once the whole group has been matched, a subsequent matching failure cannot
+cause backtracking into the middle of the group.
+.
+.
+.\" HTML 
+.SH ASSERTIONS
+.rs
+.sp
+An assertion is a test on the characters following or preceding the current
+matching point that does not actually consume any characters. The simple
+assertions coded as \eb, \eB, \eA, \eG, \eZ, \ez, ^ and $ are described
+.\" HTML 
+.\" 
+above.
+.\"
+.P
+More complicated assertions are coded as subpatterns. There are two kinds:
+those that look ahead of the current position in the subject string, and those
+that look behind it. An assertion subpattern is matched in the normal way,
+except that it does not cause the current matching position to be changed.
+.P
+Assertion subpatterns are not capturing subpatterns. If such an assertion
+contains capturing subpatterns within it, these are counted for the purposes of
+numbering the capturing subpatterns in the whole pattern. However, substring
+capturing is carried out only for positive assertions. (Perl sometimes, but not
+always, does do capturing in negative assertions.)
+.P
+For compatibility with Perl, assertion subpatterns may be repeated; though
+it makes no sense to assert the same thing several times, the side effect of
+capturing parentheses may occasionally be useful. In practice, there only three
+cases:
+.sp
+(1) If the quantifier is {0}, the assertion is never obeyed during matching.
+However, it may contain internal capturing parenthesized groups that are called
+from elsewhere via the
+.\" HTML 
+.\" 
+subroutine mechanism.
+.\"
+.sp
+(2) If quantifier is {0,n} where n is greater than zero, it is treated as if it
+were {0,1}. At run time, the rest of the pattern match is tried with and
+without the assertion, the order depending on the greediness of the quantifier.
+.sp
+(3) If the minimum repetition is greater than zero, the quantifier is ignored.
+The assertion is obeyed just once when encountered during matching.
+.
+.
+.SS "Lookahead assertions"
+.rs
+.sp
+Lookahead assertions start with (?= for positive assertions and (?! for
+negative assertions. For example,
+.sp
+  \ew+(?=;)
+.sp
+matches a word followed by a semicolon, but does not include the semicolon in
+the match, and
+.sp
+  foo(?!bar)
+.sp
+matches any occurrence of "foo" that is not followed by "bar". Note that the
+apparently similar pattern
+.sp
+  (?!foo)bar
+.sp
+does not find an occurrence of "bar" that is preceded by something other than
+"foo"; it finds any occurrence of "bar" whatsoever, because the assertion
+(?!foo) is always true when the next three characters are "bar". A
+lookbehind assertion is needed to achieve the other effect.
+.P
+If you want to force a matching failure at some point in a pattern, the most
+convenient way to do it is with (?!) because an empty string always matches, so
+an assertion that requires there not to be an empty string must always fail.
+The backtracking control verb (*FAIL) or (*F) is a synonym for (?!).
+.
+.
+.\" HTML 
+.SS "Lookbehind assertions"
+.rs
+.sp
+Lookbehind assertions start with (?<= for positive assertions and (?
+.\" 
+(see above)
+.\"
+can be used instead of a lookbehind assertion to get round the fixed-length
+restriction.
+.P
+The implementation of lookbehind assertions is, for each alternative, to
+temporarily move the current position back by the fixed length and then try to
+match. If there are insufficient characters before the current position, the
+assertion fails.
+.P
+In a UTF mode, PCRE does not allow the \eC escape (which matches a single data
+unit even in a UTF mode) to appear in lookbehind assertions, because it makes
+it impossible to calculate the length of the lookbehind. The \eX and \eR
+escapes, which can match different numbers of data units, are also not
+permitted.
+.P
+.\" HTML 
+.\" 
+"Subroutine"
+.\"
+calls (see below) such as (?2) or (?&X) are permitted in lookbehinds, as long
+as the subpattern matches a fixed-length string.
+.\" HTML 
+.\" 
+Recursion,
+.\"
+however, is not supported.
+.P
+Possessive quantifiers can be used in conjunction with lookbehind assertions to
+specify efficient matching of fixed-length strings at the end of subject
+strings. Consider a simple pattern such as
+.sp
+  abcd$
+.sp
+when applied to a long string that does not match. Because matching proceeds
+from left to right, PCRE will look for each "a" in the subject and then see if
+what follows matches the rest of the pattern. If the pattern is specified as
+.sp
+  ^.*abcd$
+.sp
+the initial .* matches the entire string at first, but when this fails (because
+there is no following "a"), it backtracks to match all but the last character,
+then all but the last two characters, and so on. Once again the search for "a"
+covers the entire string, from right to left, so we are no better off. However,
+if the pattern is written as
+.sp
+  ^.*+(?<=abcd)
+.sp
+there can be no backtracking for the .*+ item; it can match only the entire
+string. The subsequent lookbehind assertion does a single test on the last four
+characters. If it fails, the match fails immediately. For long strings, this
+approach makes a significant difference to the processing time.
+.
+.
+.SS "Using multiple assertions"
+.rs
+.sp
+Several assertions (of any sort) may occur in succession. For example,
+.sp
+  (?<=\ed{3})(?
+.SH "CONDITIONAL SUBPATTERNS"
+.rs
+.sp
+It is possible to cause the matching process to obey a subpattern
+conditionally or to choose between two alternative subpatterns, depending on
+the result of an assertion, or whether a specific capturing subpattern has
+already been matched. The two possible forms of conditional subpattern are:
+.sp
+  (?(condition)yes-pattern)
+  (?(condition)yes-pattern|no-pattern)
+.sp
+If the condition is satisfied, the yes-pattern is used; otherwise the
+no-pattern (if present) is used. If there are more than two alternatives in the
+subpattern, a compile-time error occurs. Each of the two alternatives may
+itself contain nested subpatterns of any form, including conditional
+subpatterns; the restriction to two alternatives applies only at the level of
+the condition. This pattern fragment is an example where the alternatives are
+complex:
+.sp
+  (?(1) (A|B|C) | (D | (?(2)E|F) | E) )
+.sp
+.P
+There are four kinds of condition: references to subpatterns, references to
+recursion, a pseudo-condition called DEFINE, and assertions.
+.
+.SS "Checking for a used subpattern by number"
+.rs
+.sp
+If the text between the parentheses consists of a sequence of digits, the
+condition is true if a capturing subpattern of that number has previously
+matched. If there is more than one capturing subpattern with the same number
+(see the earlier
+.\"
+.\" HTML 
+.\" 
+section about duplicate subpattern numbers),
+.\"
+the condition is true if any of them have matched. An alternative notation is
+to precede the digits with a plus or minus sign. In this case, the subpattern
+number is relative rather than absolute. The most recently opened parentheses
+can be referenced by (?(-1), the next most recent by (?(-2), and so on. Inside
+loops it can also make sense to refer to subsequent groups. The next
+parentheses to be opened can be referenced as (?(+1), and so on. (The value
+zero in any of these forms is not used; it provokes a compile-time error.)
+.P
+Consider the following pattern, which contains non-significant white space to
+make it more readable (assume the PCRE_EXTENDED option) and to divide it into
+three parts for ease of discussion:
+.sp
+  ( \e( )?    [^()]+    (?(1) \e) )
+.sp
+The first part matches an optional opening parenthesis, and if that
+character is present, sets it as the first captured substring. The second part
+matches one or more characters that are not parentheses. The third part is a
+conditional subpattern that tests whether or not the first set of parentheses
+matched. If they did, that is, if subject started with an opening parenthesis,
+the condition is true, and so the yes-pattern is executed and a closing
+parenthesis is required. Otherwise, since no-pattern is not present, the
+subpattern matches nothing. In other words, this pattern matches a sequence of
+non-parentheses, optionally enclosed in parentheses.
+.P
+If you were embedding this pattern in a larger one, you could use a relative
+reference:
+.sp
+  ...other stuff... ( \e( )?    [^()]+    (?(-1) \e) ) ...
+.sp
+This makes the fragment independent of the parentheses in the larger pattern.
+.
+.SS "Checking for a used subpattern by name"
+.rs
+.sp
+Perl uses the syntax (?()...) or (?('name')...) to test for a used
+subpattern by name. For compatibility with earlier versions of PCRE, which had
+this facility before Perl, the syntax (?(name)...) is also recognized.
+.P
+Rewriting the above example to use a named subpattern gives this:
+.sp
+  (? \e( )?    [^()]+    (?() \e) )
+.sp
+If the name used in a condition of this kind is a duplicate, the test is
+applied to all subpatterns of the same name, and is true if any one of them has
+matched.
+.
+.SS "Checking for pattern recursion"
+.rs
+.sp
+If the condition is the string (R), and there is no subpattern with the name R,
+the condition is true if a recursive call to the whole pattern or any
+subpattern has been made. If digits or a name preceded by ampersand follow the
+letter R, for example:
+.sp
+  (?(R3)...) or (?(R&name)...)
+.sp
+the condition is true if the most recent recursion is into a subpattern whose
+number or name is given. This condition does not check the entire recursion
+stack. If the name used in a condition of this kind is a duplicate, the test is
+applied to all subpatterns of the same name, and is true if any one of them is
+the most recent recursion.
+.P
+At "top level", all these recursion test conditions are false.
+.\" HTML 
+.\" 
+The syntax for recursive patterns
+.\"
+is described below.
+.
+.\" HTML 
+.SS "Defining subpatterns for use by reference only"
+.rs
+.sp
+If the condition is the string (DEFINE), and there is no subpattern with the
+name DEFINE, the condition is always false. In this case, there may be only one
+alternative in the subpattern. It is always skipped if control reaches this
+point in the pattern; the idea of DEFINE is that it can be used to define
+subroutines that can be referenced from elsewhere. (The use of
+.\" HTML 
+.\" 
+subroutines
+.\"
+is described below.) For example, a pattern to match an IPv4 address such as
+"192.168.23.245" could be written like this (ignore white space and line
+breaks):
+.sp
+  (?(DEFINE) (? 2[0-4]\ed | 25[0-5] | 1\ed\ed | [1-9]?\ed) )
+  \eb (?&byte) (\e.(?&byte)){3} \eb
+.sp
+The first part of the pattern is a DEFINE group inside which a another group
+named "byte" is defined. This matches an individual component of an IPv4
+address (a number less than 256). When matching takes place, this part of the
+pattern is skipped because DEFINE acts like a false condition. The rest of the
+pattern uses references to the named group to match the four dot-separated
+components of an IPv4 address, insisting on a word boundary at each end.
+.
+.SS "Assertion conditions"
+.rs
+.sp
+If the condition is not in any of the above formats, it must be an assertion.
+This may be a positive or negative lookahead or lookbehind assertion. Consider
+this pattern, again containing non-significant white space, and with the two
+alternatives on the second line:
+.sp
+  (?(?=[^a-z]*[a-z])
+  \ed{2}-[a-z]{3}-\ed{2}  |  \ed{2}-\ed{2}-\ed{2} )
+.sp
+The condition is a positive lookahead assertion that matches an optional
+sequence of non-letters followed by a letter. In other words, it tests for the
+presence of at least one letter in the subject. If a letter is found, the
+subject is matched against the first alternative; otherwise it is matched
+against the second. This pattern matches strings in one of the two forms
+dd-aaa-dd or dd-dd-dd, where aaa are letters and dd are digits.
+.
+.
+.\" HTML 
+.SH COMMENTS
+.rs
+.sp
+There are two ways of including comments in patterns that are processed by
+PCRE. In both cases, the start of the comment must not be in a character class,
+nor in the middle of any other sequence of related characters such as (?: or a
+subpattern name or number. The characters that make up a comment play no part
+in the pattern matching.
+.P
+The sequence (?# marks the start of a comment that continues up to the next
+closing parenthesis. Nested parentheses are not permitted. If the PCRE_EXTENDED
+option is set, an unescaped # character also introduces a comment, which in
+this case continues to immediately after the next newline character or
+character sequence in the pattern. Which characters are interpreted as newlines
+is controlled by the options passed to a compiling function or by a special
+sequence at the start of the pattern, as described in the section entitled
+.\" HTML 
+.\" 
+"Newline conventions"
+.\"
+above. Note that the end of this type of comment is a literal newline sequence
+in the pattern; escape sequences that happen to represent a newline do not
+count. For example, consider this pattern when PCRE_EXTENDED is set, and the
+default newline convention is in force:
+.sp
+  abc #comment \en still comment
+.sp
+On encountering the # character, \fBpcre_compile()\fP skips along, looking for
+a newline in the pattern. The sequence \en is still literal at this stage, so
+it does not terminate the comment. Only an actual character with the code value
+0x0a (the default newline) does so.
+.
+.
+.\" HTML 
+.SH "RECURSIVE PATTERNS"
+.rs
+.sp
+Consider the problem of matching a string in parentheses, allowing for
+unlimited nested parentheses. Without the use of recursion, the best that can
+be done is to use a pattern that matches up to some fixed depth of nesting. It
+is not possible to handle an arbitrary nesting depth.
+.P
+For some time, Perl has provided a facility that allows regular expressions to
+recurse (amongst other things). It does this by interpolating Perl code in the
+expression at run time, and the code can refer to the expression itself. A Perl
+pattern using code interpolation to solve the parentheses problem can be
+created like this:
+.sp
+  $re = qr{\e( (?: (?>[^()]+) | (?p{$re}) )* \e)}x;
+.sp
+The (?p{...}) item interpolates Perl code at run time, and in this case refers
+recursively to the pattern in which it appears.
+.P
+Obviously, PCRE cannot support the interpolation of Perl code. Instead, it
+supports special syntax for recursion of the entire pattern, and also for
+individual subpattern recursion. After its introduction in PCRE and Python,
+this kind of recursion was subsequently introduced into Perl at release 5.10.
+.P
+A special item that consists of (? followed by a number greater than zero and a
+closing parenthesis is a recursive subroutine call of the subpattern of the
+given number, provided that it occurs inside that subpattern. (If not, it is a
+.\" HTML 
+.\" 
+non-recursive subroutine
+.\"
+call, which is described in the next section.) The special item (?R) or (?0) is
+a recursive call of the entire regular expression.
+.P
+This PCRE pattern solves the nested parentheses problem (assume the
+PCRE_EXTENDED option is set so that white space is ignored):
+.sp
+  \e( ( [^()]++ | (?R) )* \e)
+.sp
+First it matches an opening parenthesis. Then it matches any number of
+substrings which can either be a sequence of non-parentheses, or a recursive
+match of the pattern itself (that is, a correctly parenthesized substring).
+Finally there is a closing parenthesis. Note the use of a possessive quantifier
+to avoid backtracking into sequences of non-parentheses.
+.P
+If this were part of a larger pattern, you would not want to recurse the entire
+pattern, so instead you could use this:
+.sp
+  ( \e( ( [^()]++ | (?1) )* \e) )
+.sp
+We have put the pattern into parentheses, and caused the recursion to refer to
+them instead of the whole pattern.
+.P
+In a larger pattern, keeping track of parenthesis numbers can be tricky. This
+is made easier by the use of relative references. Instead of (?1) in the
+pattern above you can write (?-2) to refer to the second most recently opened
+parentheses preceding the recursion. In other words, a negative number counts
+capturing parentheses leftwards from the point at which it is encountered.
+.P
+It is also possible to refer to subsequently opened parentheses, by writing
+references such as (?+2). However, these cannot be recursive because the
+reference is not inside the parentheses that are referenced. They are always
+.\" HTML 
+.\" 
+non-recursive subroutine
+.\"
+calls, as described in the next section.
+.P
+An alternative approach is to use named parentheses instead. The Perl syntax
+for this is (?&name); PCRE's earlier syntax (?P>name) is also supported. We
+could rewrite the above example as follows:
+.sp
+  (? \e( ( [^()]++ | (?&pn) )* \e) )
+.sp
+If there is more than one subpattern with the same name, the earliest one is
+used.
+.P
+This particular example pattern that we have been looking at contains nested
+unlimited repeats, and so the use of a possessive quantifier for matching
+strings of non-parentheses is important when applying the pattern to strings
+that do not match. For example, when this pattern is applied to
+.sp
+  (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
+.sp
+it yields "no match" quickly. However, if a possessive quantifier is not used,
+the match runs for a very long time indeed because there are so many different
+ways the + and * repeats can carve up the subject, and all have to be tested
+before failure can be reported.
+.P
+At the end of a match, the values of capturing parentheses are those from
+the outermost level. If you want to obtain intermediate values, a callout
+function can be used (see below and the
+.\" HREF
+\fBpcrecallout\fP
+.\"
+documentation). If the pattern above is matched against
+.sp
+  (ab(cd)ef)
+.sp
+the value for the inner capturing parentheses (numbered 2) is "ef", which is
+the last value taken on at the top level. If a capturing subpattern is not
+matched at the top level, its final captured value is unset, even if it was
+(temporarily) set at a deeper level during the matching process.
+.P
+If there are more than 15 capturing parentheses in a pattern, PCRE has to
+obtain extra memory to store data during a recursion, which it does by using
+\fBpcre_malloc\fP, freeing it via \fBpcre_free\fP afterwards. If no memory can
+be obtained, the match fails with the PCRE_ERROR_NOMEMORY error.
+.P
+Do not confuse the (?R) item with the condition (R), which tests for recursion.
+Consider this pattern, which matches text in angle brackets, allowing for
+arbitrary nesting. Only digits are allowed in nested brackets (that is, when
+recursing), whereas any characters are permitted at the outer level.
+.sp
+  < (?: (?(R) \ed++  | [^<>]*+) | (?R)) * >
+.sp
+In this pattern, (?(R) is the start of a conditional subpattern, with two
+different alternatives for the recursive and non-recursive cases. The (?R) item
+is the actual recursive call.
+.
+.
+.\" HTML 
+.SS "Differences in recursion processing between PCRE and Perl"
+.rs
+.sp
+Recursion processing in PCRE differs from Perl in two important ways. In PCRE
+(like Python, but unlike Perl), a recursive subpattern call is always treated
+as an atomic group. That is, once it has matched some of the subject string, it
+is never re-entered, even if it contains untried alternatives and there is a
+subsequent matching failure. This can be illustrated by the following pattern,
+which purports to match a palindromic string that contains an odd number of
+characters (for example, "a", "aba", "abcba", "abcdcba"):
+.sp
+  ^(.|(.)(?1)\e2)$
+.sp
+The idea is that it either matches a single character, or two identical
+characters surrounding a sub-palindrome. In Perl, this pattern works; in PCRE
+it does not if the pattern is longer than three characters. Consider the
+subject string "abcba":
+.P
+At the top level, the first character is matched, but as it is not at the end
+of the string, the first alternative fails; the second alternative is taken
+and the recursion kicks in. The recursive call to subpattern 1 successfully
+matches the next character ("b"). (Note that the beginning and end of line
+tests are not part of the recursion).
+.P
+Back at the top level, the next character ("c") is compared with what
+subpattern 2 matched, which was "a". This fails. Because the recursion is
+treated as an atomic group, there are now no backtracking points, and so the
+entire match fails. (Perl is able, at this point, to re-enter the recursion and
+try the second alternative.) However, if the pattern is written with the
+alternatives in the other order, things are different:
+.sp
+  ^((.)(?1)\e2|.)$
+.sp
+This time, the recursing alternative is tried first, and continues to recurse
+until it runs out of characters, at which point the recursion fails. But this
+time we do have another alternative to try at the higher level. That is the big
+difference: in the previous case the remaining alternative is at a deeper
+recursion level, which PCRE cannot use.
+.P
+To change the pattern so that it matches all palindromic strings, not just
+those with an odd number of characters, it is tempting to change the pattern to
+this:
+.sp
+  ^((.)(?1)\e2|.?)$
+.sp
+Again, this works in Perl, but not in PCRE, and for the same reason. When a
+deeper recursion has matched a single character, it cannot be entered again in
+order to match an empty string. The solution is to separate the two cases, and
+write out the odd and even cases as alternatives at the higher level:
+.sp
+  ^(?:((.)(?1)\e2|)|((.)(?3)\e4|.))
+.sp
+If you want to match typical palindromic phrases, the pattern has to ignore all
+non-word characters, which can be done like this:
+.sp
+  ^\eW*+(?:((.)\eW*+(?1)\eW*+\e2|)|((.)\eW*+(?3)\eW*+\e4|\eW*+.\eW*+))\eW*+$
+.sp
+If run with the PCRE_CASELESS option, this pattern matches phrases such as "A
+man, a plan, a canal: Panama!" and it works well in both PCRE and Perl. Note
+the use of the possessive quantifier *+ to avoid backtracking into sequences of
+non-word characters. Without this, PCRE takes a great deal longer (ten times or
+more) to match typical phrases, and Perl takes so long that you think it has
+gone into a loop.
+.P
+\fBWARNING\fP: The palindrome-matching patterns above work only if the subject
+string does not start with a palindrome that is shorter than the entire string.
+For example, although "abcba" is correctly matched, if the subject is "ababa",
+PCRE finds the palindrome "aba" at the start, then fails at top level because
+the end of the string does not follow. Once again, it cannot jump back into the
+recursion to try other alternatives, so the entire match fails.
+.P
+The second way in which PCRE and Perl differ in their recursion processing is
+in the handling of captured values. In Perl, when a subpattern is called
+recursively or as a subpattern (see the next section), it has no access to any
+values that were captured outside the recursion, whereas in PCRE these values
+can be referenced. Consider this pattern:
+.sp
+  ^(.)(\e1|a(?2))
+.sp
+In PCRE, this pattern matches "bab". The first capturing parentheses match "b",
+then in the second group, when the back reference \e1 fails to match "b", the
+second alternative matches "a" and then recurses. In the recursion, \e1 does
+now match "b" and so the whole match succeeds. In Perl, the pattern fails to
+match because inside the recursive call \e1 cannot access the externally set
+value.
+.
+.
+.\" HTML 
+.SH "SUBPATTERNS AS SUBROUTINES"
+.rs
+.sp
+If the syntax for a recursive subpattern call (either by number or by
+name) is used outside the parentheses to which it refers, it operates like a
+subroutine in a programming language. The called subpattern may be defined
+before or after the reference. A numbered reference can be absolute or
+relative, as in these examples:
+.sp
+  (...(absolute)...)...(?2)...
+  (...(relative)...)...(?-1)...
+  (...(?+1)...(relative)...
+.sp
+An earlier example pointed out that the pattern
+.sp
+  (sens|respons)e and \e1ibility
+.sp
+matches "sense and sensibility" and "response and responsibility", but not
+"sense and responsibility". If instead the pattern
+.sp
+  (sens|respons)e and (?1)ibility
+.sp
+is used, it does match "sense and responsibility" as well as the other two
+strings. Another example is given in the discussion of DEFINE above.
+.P
+All subroutine calls, whether recursive or not, are always treated as atomic
+groups. That is, once a subroutine has matched some of the subject string, it
+is never re-entered, even if it contains untried alternatives and there is a
+subsequent matching failure. Any capturing parentheses that are set during the
+subroutine call revert to their previous values afterwards.
+.P
+Processing options such as case-independence are fixed when a subpattern is
+defined, so if it is used as a subroutine, such options cannot be changed for
+different calls. For example, consider this pattern:
+.sp
+  (abc)(?i:(?-1))
+.sp
+It matches "abcabc". It does not match "abcABC" because the change of
+processing option does not affect the called subpattern.
+.
+.
+.\" HTML 
+.SH "ONIGURUMA SUBROUTINE SYNTAX"
+.rs
+.sp
+For compatibility with Oniguruma, the non-Perl syntax \eg followed by a name or
+a number enclosed either in angle brackets or single quotes, is an alternative
+syntax for referencing a subpattern as a subroutine, possibly recursively. Here
+are two of the examples used above, rewritten using this syntax:
+.sp
+  (? \e( ( (?>[^()]+) | \eg )* \e) )
+  (sens|respons)e and \eg'1'ibility
+.sp
+PCRE supports an extension to Oniguruma: if a number is preceded by a
+plus or a minus sign it is taken as a relative reference. For example:
+.sp
+  (abc)(?i:\eg<-1>)
+.sp
+Note that \eg{...} (Perl syntax) and \eg<...> (Oniguruma syntax) are \fInot\fP
+synonymous. The former is a back reference; the latter is a subroutine call.
+.
+.
+.SH CALLOUTS
+.rs
+.sp
+Perl has a feature whereby using the sequence (?{...}) causes arbitrary Perl
+code to be obeyed in the middle of matching a regular expression. This makes it
+possible, amongst other things, to extract different substrings that match the
+same pair of parentheses when there is a repetition.
+.P
+PCRE provides a similar feature, but of course it cannot obey arbitrary Perl
+code. The feature is called "callout". The caller of PCRE provides an external
+function by putting its entry point in the global variable \fIpcre_callout\fP
+(8-bit library) or \fIpcre[16|32]_callout\fP (16-bit or 32-bit library).
+By default, this variable contains NULL, which disables all calling out.
+.P
+Within a regular expression, (?C) indicates the points at which the external
+function is to be called. If you want to identify different callout points, you
+can put a number less than 256 after the letter C. The default value is zero.
+For example, this pattern has two callout points:
+.sp
+  (?C1)abc(?C2)def
+.sp
+If the PCRE_AUTO_CALLOUT flag is passed to a compiling function, callouts are
+automatically installed before each item in the pattern. They are all numbered
+255. If there is a conditional group in the pattern whose condition is an
+assertion, an additional callout is inserted just before the condition. An
+explicit callout may also be set at this position, as in this example:
+.sp
+  (?(?C9)(?=a)abc|def)
+.sp
+Note that this applies only to assertion conditions, not to other types of
+condition.
+.P
+During matching, when PCRE reaches a callout point, the external function is
+called. It is provided with the number of the callout, the position in the
+pattern, and, optionally, one item of data originally supplied by the caller of
+the matching function. The callout function may cause matching to proceed, to
+backtrack, or to fail altogether.
+.P
+By default, PCRE implements a number of optimizations at compile time and
+matching time, and one side-effect is that sometimes callouts are skipped. If
+you need all possible callouts to happen, you need to set options that disable
+the relevant optimizations. More details, and a complete description of the
+interface to the callout function, are given in the
+.\" HREF
+\fBpcrecallout\fP
+.\"
+documentation.
+.
+.
+.\" HTML 
+.SH "BACKTRACKING CONTROL"
+.rs
+.sp
+Perl 5.10 introduced a number of "Special Backtracking Control Verbs", which
+are still described in the Perl documentation as "experimental and subject to
+change or removal in a future version of Perl". It goes on to say: "Their usage
+in production code should be noted to avoid problems during upgrades." The same
+remarks apply to the PCRE features described in this section.
+.P
+The new verbs make use of what was previously invalid syntax: an opening
+parenthesis followed by an asterisk. They are generally of the form
+(*VERB) or (*VERB:NAME). Some may take either form, possibly behaving
+differently depending on whether or not a name is present. A name is any
+sequence of characters that does not include a closing parenthesis. The maximum
+length of name is 255 in the 8-bit library and 65535 in the 16-bit and 32-bit
+libraries. If the name is empty, that is, if the closing parenthesis
+immediately follows the colon, the effect is as if the colon were not there.
+Any number of these verbs may occur in a pattern.
+.P
+Since these verbs are specifically related to backtracking, most of them can be
+used only when the pattern is to be matched using one of the traditional
+matching functions, because these use a backtracking algorithm. With the
+exception of (*FAIL), which behaves like a failing negative assertion, the
+backtracking control verbs cause an error if encountered by a DFA matching
+function.
+.P
+The behaviour of these verbs in
+.\" HTML 
+.\" 
+repeated groups,
+.\"
+.\" HTML 
+.\" 
+assertions,
+.\"
+and in
+.\" HTML 
+.\" 
+subpatterns called as subroutines
+.\"
+(whether or not recursively) is documented below.
+.
+.
+.\" HTML 
+.SS "Optimizations that affect backtracking verbs"
+.rs
+.sp
+PCRE contains some optimizations that are used to speed up matching by running
+some checks at the start of each match attempt. For example, it may know the
+minimum length of matching subject, or that a particular character must be
+present. When one of these optimizations bypasses the running of a match, any
+included backtracking verbs will not, of course, be processed. You can suppress
+the start-of-match optimizations by setting the PCRE_NO_START_OPTIMIZE option
+when calling \fBpcre_compile()\fP or \fBpcre_exec()\fP, or by starting the
+pattern with (*NO_START_OPT). There is more discussion of this option in the
+section entitled
+.\" HTML 
+.\" 
+"Option bits for \fBpcre_exec()\fP"
+.\"
+in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation.
+.P
+Experiments with Perl suggest that it too has similar optimizations, sometimes
+leading to anomalous results.
+.
+.
+.SS "Verbs that act immediately"
+.rs
+.sp
+The following verbs act as soon as they are encountered. They may not be
+followed by a name.
+.sp
+   (*ACCEPT)
+.sp
+This verb causes the match to end successfully, skipping the remainder of the
+pattern. However, when it is inside a subpattern that is called as a
+subroutine, only that subpattern is ended successfully. Matching then continues
+at the outer level. If (*ACCEPT) in triggered in a positive assertion, the
+assertion succeeds; in a negative assertion, the assertion fails.
+.P
+If (*ACCEPT) is inside capturing parentheses, the data so far is captured. For
+example:
+.sp
+  A((?:A|B(*ACCEPT)|C)D)
+.sp
+This matches "AB", "AAD", or "ACD"; when it matches "AB", "B" is captured by
+the outer parentheses.
+.sp
+  (*FAIL) or (*F)
+.sp
+This verb causes a matching failure, forcing backtracking to occur. It is
+equivalent to (?!) but easier to read. The Perl documentation notes that it is
+probably useful only when combined with (?{}) or (??{}). Those are, of course,
+Perl features that are not present in PCRE. The nearest equivalent is the
+callout feature, as for example in this pattern:
+.sp
+  a+(?C)(*FAIL)
+.sp
+A match with the string "aaaa" always fails, but the callout is taken before
+each backtrack happens (in this example, 10 times).
+.
+.
+.SS "Recording which path was taken"
+.rs
+.sp
+There is one verb whose main purpose is to track how a match was arrived at,
+though it also has a secondary use in conjunction with advancing the match
+starting point (see (*SKIP) below).
+.sp
+  (*MARK:NAME) or (*:NAME)
+.sp
+A name is always required with this verb. There may be as many instances of
+(*MARK) as you like in a pattern, and their names do not have to be unique.
+.P
+When a match succeeds, the name of the last-encountered (*MARK:NAME),
+(*PRUNE:NAME), or (*THEN:NAME) on the matching path is passed back to the
+caller as described in the section entitled
+.\" HTML 
+.\" 
+"Extra data for \fBpcre_exec()\fP"
+.\"
+in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation. Here is an example of \fBpcretest\fP output, where the /K
+modifier requests the retrieval and outputting of (*MARK) data:
+.sp
+    re> /X(*MARK:A)Y|X(*MARK:B)Z/K
+  data> XY
+   0: XY
+  MK: A
+  XZ
+   0: XZ
+  MK: B
+.sp
+The (*MARK) name is tagged with "MK:" in this output, and in this example it
+indicates which of the two alternatives matched. This is a more efficient way
+of obtaining this information than putting each alternative in its own
+capturing parentheses.
+.P
+If a verb with a name is encountered in a positive assertion that is true, the
+name is recorded and passed back if it is the last-encountered. This does not
+happen for negative assertions or failing positive assertions.
+.P
+After a partial match or a failed match, the last encountered name in the
+entire match process is returned. For example:
+.sp
+    re> /X(*MARK:A)Y|X(*MARK:B)Z/K
+  data> XP
+  No match, mark = B
+.sp
+Note that in this unanchored example the mark is retained from the match
+attempt that started at the letter "X" in the subject. Subsequent match
+attempts starting at "P" and then with an empty string do not get as far as the
+(*MARK) item, but nevertheless do not reset it.
+.P
+If you are interested in (*MARK) values after failed matches, you should
+probably set the PCRE_NO_START_OPTIMIZE option
+.\" HTML 
+.\" 
+(see above)
+.\"
+to ensure that the match is always attempted.
+.
+.
+.SS "Verbs that act after backtracking"
+.rs
+.sp
+The following verbs do nothing when they are encountered. Matching continues
+with what follows, but if there is no subsequent match, causing a backtrack to
+the verb, a failure is forced. That is, backtracking cannot pass to the left of
+the verb. However, when one of these verbs appears inside an atomic group or an
+assertion that is true, its effect is confined to that group, because once the
+group has been matched, there is never any backtracking into it. In this
+situation, backtracking can "jump back" to the left of the entire atomic group
+or assertion. (Remember also, as stated above, that this localization also
+applies in subroutine calls.)
+.P
+These verbs differ in exactly what kind of failure occurs when backtracking
+reaches them. The behaviour described below is what happens when the verb is
+not in a subroutine or an assertion. Subsequent sections cover these special
+cases.
+.sp
+  (*COMMIT)
+.sp
+This verb, which may not be followed by a name, causes the whole match to fail
+outright if there is a later matching failure that causes backtracking to reach
+it. Even if the pattern is unanchored, no further attempts to find a match by
+advancing the starting point take place. If (*COMMIT) is the only backtracking
+verb that is encountered, once it has been passed \fBpcre_exec()\fP is
+committed to finding a match at the current starting point, or not at all. For
+example:
+.sp
+  a+(*COMMIT)b
+.sp
+This matches "xxaab" but not "aacaab". It can be thought of as a kind of
+dynamic anchor, or "I've started, so I must finish." The name of the most
+recently passed (*MARK) in the path is passed back when (*COMMIT) forces a
+match failure.
+.P
+If there is more than one backtracking verb in a pattern, a different one that
+follows (*COMMIT) may be triggered first, so merely passing (*COMMIT) during a
+match does not always guarantee that a match must be at this starting point.
+.P
+Note that (*COMMIT) at the start of a pattern is not the same as an anchor,
+unless PCRE's start-of-match optimizations are turned off, as shown in this
+output from \fBpcretest\fP:
+.sp
+    re> /(*COMMIT)abc/
+  data> xyzabc
+   0: abc
+  data> xyzabc\eY
+  No match
+.sp
+For this pattern, PCRE knows that any match must start with "a", so the
+optimization skips along the subject to "a" before applying the pattern to the
+first set of data. The match attempt then succeeds. In the second set of data,
+the escape sequence \eY is interpreted by the \fBpcretest\fP program. It causes
+the PCRE_NO_START_OPTIMIZE option to be set when \fBpcre_exec()\fP is called.
+This disables the optimization that skips along to the first character. The
+pattern is now applied starting at "x", and so the (*COMMIT) causes the match
+to fail without trying any other starting points.
+.sp
+  (*PRUNE) or (*PRUNE:NAME)
+.sp
+This verb causes the match to fail at the current starting position in the
+subject if there is a later matching failure that causes backtracking to reach
+it. If the pattern is unanchored, the normal "bumpalong" advance to the next
+starting character then happens. Backtracking can occur as usual to the left of
+(*PRUNE), before it is reached, or when matching to the right of (*PRUNE), but
+if there is no match to the right, backtracking cannot cross (*PRUNE). In
+simple cases, the use of (*PRUNE) is just an alternative to an atomic group or
+possessive quantifier, but there are some uses of (*PRUNE) that cannot be
+expressed in any other way. In an anchored pattern (*PRUNE) has the same effect
+as (*COMMIT).
+.P
+The behaviour of (*PRUNE:NAME) is the not the same as (*MARK:NAME)(*PRUNE).
+It is like (*MARK:NAME) in that the name is remembered for passing back to the
+caller. However, (*SKIP:NAME) searches only for names set with (*MARK).
+.sp
+  (*SKIP)
+.sp
+This verb, when given without a name, is like (*PRUNE), except that if the
+pattern is unanchored, the "bumpalong" advance is not to the next character,
+but to the position in the subject where (*SKIP) was encountered. (*SKIP)
+signifies that whatever text was matched leading up to it cannot be part of a
+successful match. Consider:
+.sp
+  a+(*SKIP)b
+.sp
+If the subject is "aaaac...", after the first match attempt fails (starting at
+the first character in the string), the starting point skips on to start the
+next attempt at "c". Note that a possessive quantifer does not have the same
+effect as this example; although it would suppress backtracking during the
+first match attempt, the second attempt would start at the second character
+instead of skipping on to "c".
+.sp
+  (*SKIP:NAME)
+.sp
+When (*SKIP) has an associated name, its behaviour is modified. When it is
+triggered, the previous path through the pattern is searched for the most
+recent (*MARK) that has the same name. If one is found, the "bumpalong" advance
+is to the subject position that corresponds to that (*MARK) instead of to where
+(*SKIP) was encountered. If no (*MARK) with a matching name is found, the
+(*SKIP) is ignored.
+.P
+Note that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It ignores
+names that are set by (*PRUNE:NAME) or (*THEN:NAME).
+.sp
+  (*THEN) or (*THEN:NAME)
+.sp
+This verb causes a skip to the next innermost alternative when backtracking
+reaches it. That is, it cancels any further backtracking within the current
+alternative. Its name comes from the observation that it can be used for a
+pattern-based if-then-else block:
+.sp
+  ( COND1 (*THEN) FOO | COND2 (*THEN) BAR | COND3 (*THEN) BAZ ) ...
+.sp
+If the COND1 pattern matches, FOO is tried (and possibly further items after
+the end of the group if FOO succeeds); on failure, the matcher skips to the
+second alternative and tries COND2, without backtracking into COND1. If that
+succeeds and BAR fails, COND3 is tried. If subsequently BAZ fails, there are no
+more alternatives, so there is a backtrack to whatever came before the entire
+group. If (*THEN) is not inside an alternation, it acts like (*PRUNE).
+.P
+The behaviour of (*THEN:NAME) is the not the same as (*MARK:NAME)(*THEN).
+It is like (*MARK:NAME) in that the name is remembered for passing back to the
+caller. However, (*SKIP:NAME) searches only for names set with (*MARK).
+.P
+A subpattern that does not contain a | character is just a part of the
+enclosing alternative; it is not a nested alternation with only one
+alternative. The effect of (*THEN) extends beyond such a subpattern to the
+enclosing alternative. Consider this pattern, where A, B, etc. are complex
+pattern fragments that do not contain any | characters at this level:
+.sp
+  A (B(*THEN)C) | D
+.sp
+If A and B are matched, but there is a failure in C, matching does not
+backtrack into A; instead it moves to the next alternative, that is, D.
+However, if the subpattern containing (*THEN) is given an alternative, it
+behaves differently:
+.sp
+  A (B(*THEN)C | (*FAIL)) | D
+.sp
+The effect of (*THEN) is now confined to the inner subpattern. After a failure
+in C, matching moves to (*FAIL), which causes the whole subpattern to fail
+because there are no more alternatives to try. In this case, matching does now
+backtrack into A.
+.P
+Note that a conditional subpattern is not considered as having two
+alternatives, because only one is ever used. In other words, the | character in
+a conditional subpattern has a different meaning. Ignoring white space,
+consider:
+.sp
+  ^.*? (?(?=a) a | b(*THEN)c )
+.sp
+If the subject is "ba", this pattern does not match. Because .*? is ungreedy,
+it initially matches zero characters. The condition (?=a) then fails, the
+character "b" is matched, but "c" is not. At this point, matching does not
+backtrack to .*? as might perhaps be expected from the presence of the |
+character. The conditional subpattern is part of the single alternative that
+comprises the whole pattern, and so the match fails. (If there was a backtrack
+into .*?, allowing it to match "b", the match would succeed.)
+.P
+The verbs just described provide four different "strengths" of control when
+subsequent matching fails. (*THEN) is the weakest, carrying on the match at the
+next alternative. (*PRUNE) comes next, failing the match at the current
+starting position, but allowing an advance to the next character (for an
+unanchored pattern). (*SKIP) is similar, except that the advance may be more
+than one character. (*COMMIT) is the strongest, causing the entire match to
+fail.
+.
+.
+.SS "More than one backtracking verb"
+.rs
+.sp
+If more than one backtracking verb is present in a pattern, the one that is
+backtracked onto first acts. For example, consider this pattern, where A, B,
+etc. are complex pattern fragments:
+.sp
+  (A(*COMMIT)B(*THEN)C|ABD)
+.sp
+If A matches but B fails, the backtrack to (*COMMIT) causes the entire match to
+fail. However, if A and B match, but C fails, the backtrack to (*THEN) causes
+the next alternative (ABD) to be tried. This behaviour is consistent, but is
+not always the same as Perl's. It means that if two or more backtracking verbs
+appear in succession, all the the last of them has no effect. Consider this
+example:
+.sp
+  ...(*COMMIT)(*PRUNE)...
+.sp
+If there is a matching failure to the right, backtracking onto (*PRUNE) causes
+it to be triggered, and its action is taken. There can never be a backtrack
+onto (*COMMIT).
+.
+.
+.\" HTML 
+.SS "Backtracking verbs in repeated groups"
+.rs
+.sp
+PCRE differs from Perl in its handling of backtracking verbs in repeated
+groups. For example, consider:
+.sp
+  /(a(*COMMIT)b)+ac/
+.sp
+If the subject is "abac", Perl matches, but PCRE fails because the (*COMMIT) in
+the second repeat of the group acts.
+.
+.
+.\" HTML 
+.SS "Backtracking verbs in assertions"
+.rs
+.sp
+(*FAIL) in an assertion has its normal effect: it forces an immediate backtrack.
+.P
+(*ACCEPT) in a positive assertion causes the assertion to succeed without any
+further processing. In a negative assertion, (*ACCEPT) causes the assertion to
+fail without any further processing.
+.P
+The other backtracking verbs are not treated specially if they appear in a
+positive assertion. In particular, (*THEN) skips to the next alternative in the
+innermost enclosing group that has alternations, whether or not this is within
+the assertion.
+.P
+Negative assertions are, however, different, in order to ensure that changing a
+positive assertion into a negative assertion changes its result. Backtracking
+into (*COMMIT), (*SKIP), or (*PRUNE) causes a negative assertion to be true,
+without considering any further alternative branches in the assertion.
+Backtracking into (*THEN) causes it to skip to the next enclosing alternative
+within the assertion (the normal behaviour), but if the assertion does not have
+such an alternative, (*THEN) behaves like (*PRUNE).
+.
+.
+.\" HTML 
+.SS "Backtracking verbs in subroutines"
+.rs
+.sp
+These behaviours occur whether or not the subpattern is called recursively.
+Perl's treatment of subroutines is different in some cases.
+.P
+(*FAIL) in a subpattern called as a subroutine has its normal effect: it forces
+an immediate backtrack.
+.P
+(*ACCEPT) in a subpattern called as a subroutine causes the subroutine match to
+succeed without any further processing. Matching then continues after the
+subroutine call.
+.P
+(*COMMIT), (*SKIP), and (*PRUNE) in a subpattern called as a subroutine cause
+the subroutine match to fail.
+.P
+(*THEN) skips to the next alternative in the innermost enclosing group within
+the subpattern that has alternatives. If there is no such group within the
+subpattern, (*THEN) causes the subroutine match to fail.
+.
+.
+.SH "SEE ALSO"
+.rs
+.sp
+\fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
+\fBpcresyntax\fP(3), \fBpcre\fP(3), \fBpcre16(3)\fP, \fBpcre32(3)\fP.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 08 January 2014
+Copyright (c) 1997-2014 University of Cambridge.
+.fi
diff --git a/doc/pcreperform.3 b/doc/pcreperform.3
new file mode 100644
index 0000000..fb2aa95
--- /dev/null
+++ b/doc/pcreperform.3
@@ -0,0 +1,177 @@
+.TH PCREPERFORM 3 "09 January 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "PCRE PERFORMANCE"
+.rs
+.sp
+Two aspects of performance are discussed below: memory usage and processing
+time. The way you express your pattern as a regular expression can affect both
+of them.
+.
+.SH "COMPILED PATTERN MEMORY USAGE"
+.rs
+.sp
+Patterns are compiled by PCRE into a reasonably efficient interpretive code, so
+that most simple patterns do not use much memory. However, there is one case
+where the memory usage of a compiled pattern can be unexpectedly large. If a
+parenthesized subpattern has a quantifier with a minimum greater than 1 and/or
+a limited maximum, the whole subpattern is repeated in the compiled code. For
+example, the pattern
+.sp
+  (abc|def){2,4}
+.sp
+is compiled as if it were
+.sp
+  (abc|def)(abc|def)((abc|def)(abc|def)?)?
+.sp
+(Technical aside: It is done this way so that backtrack points within each of
+the repetitions can be independently maintained.)
+.P
+For regular expressions whose quantifiers use only small numbers, this is not
+usually a problem. However, if the numbers are large, and particularly if such
+repetitions are nested, the memory usage can become an embarrassment. For
+example, the very simple pattern
+.sp
+  ((ab){1,1000}c){1,3}
+.sp
+uses 51K bytes when compiled using the 8-bit library. When PCRE is compiled
+with its default internal pointer size of two bytes, the size limit on a
+compiled pattern is 64K data units, and this is reached with the above pattern
+if the outer repetition is increased from 3 to 4. PCRE can be compiled to use
+larger internal pointers and thus handle larger compiled patterns, but it is
+better to try to rewrite your pattern to use less memory if you can.
+.P
+One way of reducing the memory usage for such patterns is to make use of PCRE's
+.\" HTML 
+.\" 
+"subroutine"
+.\"
+facility. Re-writing the above pattern as
+.sp
+  ((ab)(?2){0,999}c)(?1){0,2}
+.sp
+reduces the memory requirements to 18K, and indeed it remains under 20K even
+with the outer repetition increased to 100. However, this pattern is not
+exactly equivalent, because the "subroutine" calls are treated as
+.\" HTML 
+.\" 
+atomic groups
+.\"
+into which there can be no backtracking if there is a subsequent matching
+failure. Therefore, PCRE cannot do this kind of rewriting automatically.
+Furthermore, there is a noticeable loss of speed when executing the modified
+pattern. Nevertheless, if the atomic grouping is not a problem and the loss of
+speed is acceptable, this kind of rewriting will allow you to process patterns
+that PCRE cannot otherwise handle.
+.
+.
+.SH "STACK USAGE AT RUN TIME"
+.rs
+.sp
+When \fBpcre_exec()\fP or \fBpcre[16|32]_exec()\fP is used for matching, certain
+kinds of pattern can cause it to use large amounts of the process stack. In
+some environments the default process stack is quite small, and if it runs out
+the result is often SIGSEGV. This issue is probably the most frequently raised
+problem with PCRE. Rewriting your pattern can often help. The
+.\" HREF
+\fBpcrestack\fP
+.\"
+documentation discusses this issue in detail.
+.
+.
+.SH "PROCESSING TIME"
+.rs
+.sp
+Certain items in regular expression patterns are processed more efficiently
+than others. It is more efficient to use a character class like [aeiou] than a
+set of single-character alternatives such as (a|e|i|o|u). In general, the
+simplest construction that provides the required behaviour is usually the most
+efficient. Jeffrey Friedl's book contains a lot of useful general discussion
+about optimizing regular expressions for efficient performance. This document
+contains a few observations about PCRE.
+.P
+Using Unicode character properties (the \ep, \eP, and \eX escapes) is slow,
+because PCRE has to use a multi-stage table lookup whenever it needs a
+character's property. If you can find an alternative pattern that does not use
+character properties, it will probably be faster.
+.P
+By default, the escape sequences \eb, \ed, \es, and \ew, and the POSIX
+character classes such as [:alpha:] do not use Unicode properties, partly for
+backwards compatibility, and partly for performance reasons. However, you can
+set PCRE_UCP if you want Unicode character properties to be used. This can
+double the matching time for items such as \ed, when matched with
+a traditional matching function; the performance loss is less with
+a DFA matching function, and in both cases there is not much difference for
+\eb.
+.P
+When a pattern begins with .* not in parentheses, or in parentheses that are
+not the subject of a backreference, and the PCRE_DOTALL option is set, the
+pattern is implicitly anchored by PCRE, since it can match only at the start of
+a subject string. However, if PCRE_DOTALL is not set, PCRE cannot make this
+optimization, because the . metacharacter does not then match a newline, and if
+the subject string contains newlines, the pattern may match from the character
+immediately following one of them instead of from the very start. For example,
+the pattern
+.sp
+  .*second
+.sp
+matches the subject "first\enand second" (where \en stands for a newline
+character), with the match starting at the seventh character. In order to do
+this, PCRE has to retry the match starting after every newline in the subject.
+.P
+If you are using such a pattern with subject strings that do not contain
+newlines, the best performance is obtained by setting PCRE_DOTALL, or starting
+the pattern with ^.* or ^.*? to indicate explicit anchoring. That saves PCRE
+from having to scan along the subject looking for a newline to restart at.
+.P
+Beware of patterns that contain nested indefinite repeats. These can take a
+long time to run when applied to a string that does not match. Consider the
+pattern fragment
+.sp
+  ^(a+)*
+.sp
+This can match "aaaa" in 16 different ways, and this number increases very
+rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4
+times, and for each of those cases other than 0 or 4, the + repeats can match
+different numbers of times.) When the remainder of the pattern is such that the
+entire match is going to fail, PCRE has in principle to try every possible
+variation, and this can take an extremely long time, even for relatively short
+strings.
+.P
+An optimization catches some of the more simple cases such as
+.sp
+  (a+)*b
+.sp
+where a literal character follows. Before embarking on the standard matching
+procedure, PCRE checks that there is a "b" later in the subject string, and if
+there is not, it fails the match immediately. However, when there is no
+following literal this optimization cannot be used. You can see the difference
+by comparing the behaviour of
+.sp
+  (a+)*\ed
+.sp
+with the pattern above. The former gives a failure almost instantly when
+applied to a whole line of "a" characters, whereas the latter takes an
+appreciable time with strings longer than about 20 characters.
+.P
+In many cases, the solution to this kind of performance issue is to use an
+atomic group or a possessive quantifier.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 25 August 2012
+Copyright (c) 1997-2012 University of Cambridge.
+.fi
diff --git a/doc/pcreposix.3 b/doc/pcreposix.3
new file mode 100644
index 0000000..77890f3
--- /dev/null
+++ b/doc/pcreposix.3
@@ -0,0 +1,267 @@
+.TH PCREPOSIX 3 "09 January 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions.
+.SH "SYNOPSIS"
+.rs
+.sp
+.B #include 
+.PP
+.nf
+.B int regcomp(regex_t *\fIpreg\fP, const char *\fIpattern\fP,
+.B "     int \fIcflags\fP);"
+.sp
+.B int regexec(regex_t *\fIpreg\fP, const char *\fIstring\fP,
+.B "     size_t \fInmatch\fP, regmatch_t \fIpmatch\fP[], int \fIeflags\fP);"
+.B "     size_t regerror(int \fIerrcode\fP, const regex_t *\fIpreg\fP,"
+.B "     char *\fIerrbuf\fP, size_t \fIerrbuf_size\fP);"
+.sp
+.B void regfree(regex_t *\fIpreg\fP);
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This set of functions provides a POSIX-style API for the PCRE regular
+expression 8-bit library. See the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation for a description of PCRE's native API, which contains much
+additional functionality. There is no POSIX-style wrapper for PCRE's 16-bit
+and 32-bit library.
+.P
+The functions described here are just wrapper functions that ultimately call
+the PCRE native API. Their prototypes are defined in the \fBpcreposix.h\fP
+header file, and on Unix systems the library itself is called
+\fBpcreposix.a\fP, so can be accessed by adding \fB-lpcreposix\fP to the
+command for linking an application that uses them. Because the POSIX functions
+call the native ones, it is also necessary to add \fB-lpcre\fP.
+.P
+I have implemented only those POSIX option bits that can be reasonably mapped
+to PCRE native options. In addition, the option REG_EXTENDED is defined with
+the value zero. This has no effect, but since programs that are written to the
+POSIX interface often use it, this makes it easier to slot in PCRE as a
+replacement library. Other POSIX options are not even defined.
+.P
+There are also some other options that are not defined by POSIX. These have
+been added at the request of users who want to make use of certain
+PCRE-specific features via the POSIX calling interface.
+.P
+When PCRE is called via these functions, it is only the API that is POSIX-like
+in style. The syntax and semantics of the regular expressions themselves are
+still those of Perl, subject to the setting of various PCRE options, as
+described below. "POSIX-like in style" means that the API approximates to the
+POSIX definition; it is not fully POSIX-compatible, and in multi-byte encoding
+domains it is probably even less compatible.
+.P
+The header for these functions is supplied as \fBpcreposix.h\fP to avoid any
+potential clash with other POSIX libraries. It can, of course, be renamed or
+aliased as \fBregex.h\fP, which is the "correct" name. It provides two
+structure types, \fIregex_t\fP for compiled internal forms, and
+\fIregmatch_t\fP for returning captured substrings. It also defines some
+constants whose names start with "REG_"; these are used for setting options and
+identifying error codes.
+.
+.
+.SH "COMPILING A PATTERN"
+.rs
+.sp
+The function \fBregcomp()\fP is called to compile a pattern into an
+internal form. The pattern is a C string terminated by a binary zero, and
+is passed in the argument \fIpattern\fP. The \fIpreg\fP argument is a pointer
+to a \fBregex_t\fP structure that is used as a base for storing information
+about the compiled regular expression.
+.P
+The argument \fIcflags\fP is either zero, or contains one or more of the bits
+defined by the following macros:
+.sp
+  REG_DOTALL
+.sp
+The PCRE_DOTALL option is set when the regular expression is passed for
+compilation to the native function. Note that REG_DOTALL is not part of the
+POSIX standard.
+.sp
+  REG_ICASE
+.sp
+The PCRE_CASELESS option is set when the regular expression is passed for
+compilation to the native function.
+.sp
+  REG_NEWLINE
+.sp
+The PCRE_MULTILINE option is set when the regular expression is passed for
+compilation to the native function. Note that this does \fInot\fP mimic the
+defined POSIX behaviour for REG_NEWLINE (see the following section).
+.sp
+  REG_NOSUB
+.sp
+The PCRE_NO_AUTO_CAPTURE option is set when the regular expression is passed
+for compilation to the native function. In addition, when a pattern that is
+compiled with this flag is passed to \fBregexec()\fP for matching, the
+\fInmatch\fP and \fIpmatch\fP arguments are ignored, and no captured strings
+are returned.
+.sp
+  REG_UCP
+.sp
+The PCRE_UCP option is set when the regular expression is passed for
+compilation to the native function. This causes PCRE to use Unicode properties
+when matchine \ed, \ew, etc., instead of just recognizing ASCII values. Note
+that REG_UTF8 is not part of the POSIX standard.
+.sp
+  REG_UNGREEDY
+.sp
+The PCRE_UNGREEDY option is set when the regular expression is passed for
+compilation to the native function. Note that REG_UNGREEDY is not part of the
+POSIX standard.
+.sp
+  REG_UTF8
+.sp
+The PCRE_UTF8 option is set when the regular expression is passed for
+compilation to the native function. This causes the pattern itself and all data
+strings used for matching it to be treated as UTF-8 strings. Note that REG_UTF8
+is not part of the POSIX standard.
+.P
+In the absence of these flags, no options are passed to the native function.
+This means the the regex is compiled with PCRE default semantics. In
+particular, the way it handles newline characters in the subject string is the
+Perl way, not the POSIX way. Note that setting PCRE_MULTILINE has only
+\fIsome\fP of the effects specified for REG_NEWLINE. It does not affect the way
+newlines are matched by . (they are not) or by a negative class such as [^a]
+(they are).
+.P
+The yield of \fBregcomp()\fP is zero on success, and non-zero otherwise. The
+\fIpreg\fP structure is filled in on success, and one member of the structure
+is public: \fIre_nsub\fP contains the number of capturing subpatterns in
+the regular expression. Various error codes are defined in the header file.
+.P
+NOTE: If the yield of \fBregcomp()\fP is non-zero, you must not attempt to
+use the contents of the \fIpreg\fP structure. If, for example, you pass it to
+\fBregexec()\fP, the result is undefined and your program is likely to crash.
+.
+.
+.SH "MATCHING NEWLINE CHARACTERS"
+.rs
+.sp
+This area is not simple, because POSIX and Perl take different views of things.
+It is not possible to get PCRE to obey POSIX semantics, but then PCRE was never
+intended to be a POSIX engine. The following table lists the different
+possibilities for matching newline characters in PCRE:
+.sp
+                          Default   Change with
+.sp
+  . matches newline          no     PCRE_DOTALL
+  newline matches [^a]       yes    not changeable
+  $ matches \en at end        yes    PCRE_DOLLARENDONLY
+  $ matches \en in middle     no     PCRE_MULTILINE
+  ^ matches \en in middle     no     PCRE_MULTILINE
+.sp
+This is the equivalent table for POSIX:
+.sp
+                          Default   Change with
+.sp
+  . matches newline          yes    REG_NEWLINE
+  newline matches [^a]       yes    REG_NEWLINE
+  $ matches \en at end        no     REG_NEWLINE
+  $ matches \en in middle     no     REG_NEWLINE
+  ^ matches \en in middle     no     REG_NEWLINE
+.sp
+PCRE's behaviour is the same as Perl's, except that there is no equivalent for
+PCRE_DOLLAR_ENDONLY in Perl. In both PCRE and Perl, there is no way to stop
+newline from matching [^a].
+.P
+The default POSIX newline handling can be obtained by setting PCRE_DOTALL and
+PCRE_DOLLAR_ENDONLY, but there is no way to make PCRE behave exactly as for the
+REG_NEWLINE action.
+.
+.
+.SH "MATCHING A PATTERN"
+.rs
+.sp
+The function \fBregexec()\fP is called to match a compiled pattern \fIpreg\fP
+against a given \fIstring\fP, which is by default terminated by a zero byte
+(but see REG_STARTEND below), subject to the options in \fIeflags\fP. These can
+be:
+.sp
+  REG_NOTBOL
+.sp
+The PCRE_NOTBOL option is set when calling the underlying PCRE matching
+function.
+.sp
+  REG_NOTEMPTY
+.sp
+The PCRE_NOTEMPTY option is set when calling the underlying PCRE matching
+function. Note that REG_NOTEMPTY is not part of the POSIX standard. However,
+setting this option can give more POSIX-like behaviour in some situations.
+.sp
+  REG_NOTEOL
+.sp
+The PCRE_NOTEOL option is set when calling the underlying PCRE matching
+function.
+.sp
+  REG_STARTEND
+.sp
+The string is considered to start at \fIstring\fP + \fIpmatch[0].rm_so\fP and
+to have a terminating NUL located at \fIstring\fP + \fIpmatch[0].rm_eo\fP
+(there need not actually be a NUL at that location), regardless of the value of
+\fInmatch\fP. This is a BSD extension, compatible with but not specified by
+IEEE Standard 1003.2 (POSIX.2), and should be used with caution in software
+intended to be portable to other systems. Note that a non-zero \fIrm_so\fP does
+not imply REG_NOTBOL; REG_STARTEND affects only the location of the string, not
+how it is matched.
+.P
+If the pattern was compiled with the REG_NOSUB flag, no data about any matched
+strings is returned. The \fInmatch\fP and \fIpmatch\fP arguments of
+\fBregexec()\fP are ignored.
+.P
+If the value of \fInmatch\fP is zero, or if the value \fIpmatch\fP is NULL,
+no data about any matched strings is returned.
+.P
+Otherwise,the portion of the string that was matched, and also any captured
+substrings, are returned via the \fIpmatch\fP argument, which points to an
+array of \fInmatch\fP structures of type \fIregmatch_t\fP, containing the
+members \fIrm_so\fP and \fIrm_eo\fP. These contain the offset to the first
+character of each substring and the offset to the first character after the end
+of each substring, respectively. The 0th element of the vector relates to the
+entire portion of \fIstring\fP that was matched; subsequent elements relate to
+the capturing subpatterns of the regular expression. Unused entries in the
+array have both structure members set to -1.
+.P
+A successful match yields a zero return; various error codes are defined in the
+header file, of which REG_NOMATCH is the "expected" failure code.
+.
+.
+.SH "ERROR MESSAGES"
+.rs
+.sp
+The \fBregerror()\fP function maps a non-zero errorcode from either
+\fBregcomp()\fP or \fBregexec()\fP to a printable message. If \fIpreg\fP is not
+NULL, the error should have arisen from the use of that structure. A message
+terminated by a binary zero is placed in \fIerrbuf\fP. The length of the
+message, including the zero, is limited to \fIerrbuf_size\fP. The yield of the
+function is the size of buffer needed to hold the whole message.
+.
+.
+.SH MEMORY USAGE
+.rs
+.sp
+Compiling a regular expression causes memory to be allocated and associated
+with the \fIpreg\fP structure. The function \fBregfree()\fP frees all such
+memory, after which \fIpreg\fP may no longer be used as a compiled expression.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 09 January 2012
+Copyright (c) 1997-2012 University of Cambridge.
+.fi
diff --git a/doc/pcreprecompile.3 b/doc/pcreprecompile.3
new file mode 100644
index 0000000..40f257a
--- /dev/null
+++ b/doc/pcreprecompile.3
@@ -0,0 +1,155 @@
+.TH PCREPRECOMPILE 3 "12 November 2013" "PCRE 8.34"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "SAVING AND RE-USING PRECOMPILED PCRE PATTERNS"
+.rs
+.sp
+If you are running an application that uses a large number of regular
+expression patterns, it may be useful to store them in a precompiled form
+instead of having to compile them every time the application is run.
+If you are not using any private character tables (see the
+.\" HREF
+\fBpcre_maketables()\fP
+.\"
+documentation), this is relatively straightforward. If you are using private
+tables, it is a little bit more complicated. However, if you are using the
+just-in-time optimization feature, it is not possible to save and reload the
+JIT data.
+.P
+If you save compiled patterns to a file, you can copy them to a different host
+and run them there. If the two hosts have different endianness (byte order),
+you should run the \fBpcre[16|32]_pattern_to_host_byte_order()\fP function on the
+new host before trying to match the pattern. The matching functions return
+PCRE_ERROR_BADENDIANNESS if they detect a pattern with the wrong endianness.
+.P
+Compiling regular expressions with one version of PCRE for use with a different
+version is not guaranteed to work and may cause crashes, and saving and
+restoring a compiled pattern loses any JIT optimization data.
+.
+.
+.SH "SAVING A COMPILED PATTERN"
+.rs
+.sp
+The value returned by \fBpcre[16|32]_compile()\fP points to a single block of
+memory that holds the compiled pattern and associated data. You can find the
+length of this block in bytes by calling \fBpcre[16|32]_fullinfo()\fP with an
+argument of PCRE_INFO_SIZE. You can then save the data in any appropriate
+manner. Here is sample code for the 8-bit library that compiles a pattern and
+writes it to a file. It assumes that the variable \fIfd\fP refers to a file
+that is open for output:
+.sp
+  int erroroffset, rc, size;
+  char *error;
+  pcre *re;
+.sp
+  re = pcre_compile("my pattern", 0, &error, &erroroffset, NULL);
+  if (re == NULL) { ... handle errors ... }
+  rc = pcre_fullinfo(re, NULL, PCRE_INFO_SIZE, &size);
+  if (rc < 0) { ... handle errors ... }
+  rc = fwrite(re, 1, size, fd);
+  if (rc != size) { ... handle errors ... }
+.sp
+In this example, the bytes that comprise the compiled pattern are copied
+exactly. Note that this is binary data that may contain any of the 256 possible
+byte values. On systems that make a distinction between binary and non-binary
+data, be sure that the file is opened for binary output.
+.P
+If you want to write more than one pattern to a file, you will have to devise a
+way of separating them. For binary data, preceding each pattern with its length
+is probably the most straightforward approach. Another possibility is to write
+out the data in hexadecimal instead of binary, one pattern to a line.
+.P
+Saving compiled patterns in a file is only one possible way of storing them for
+later use. They could equally well be saved in a database, or in the memory of
+some daemon process that passes them via sockets to the processes that want
+them.
+.P
+If the pattern has been studied, it is also possible to save the normal study
+data in a similar way to the compiled pattern itself. However, if the
+PCRE_STUDY_JIT_COMPILE was used, the just-in-time data that is created cannot
+be saved because it is too dependent on the current environment. When studying
+generates additional information, \fBpcre[16|32]_study()\fP returns a pointer to a
+\fBpcre[16|32]_extra\fP data block. Its format is defined in the
+.\" HTML 
+.\" 
+section on matching a pattern
+.\"
+in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation. The \fIstudy_data\fP field points to the binary study data, and
+this is what you must save (not the \fBpcre[16|32]_extra\fP block itself). The
+length of the study data can be obtained by calling \fBpcre[16|32]_fullinfo()\fP
+with an argument of PCRE_INFO_STUDYSIZE. Remember to check that
+\fBpcre[16|32]_study()\fP did return a non-NULL value before trying to save the
+study data.
+.
+.
+.SH "RE-USING A PRECOMPILED PATTERN"
+.rs
+.sp
+Re-using a precompiled pattern is straightforward. Having reloaded it into main
+memory, called \fBpcre[16|32]_pattern_to_host_byte_order()\fP if necessary, you
+pass its pointer to \fBpcre[16|32]_exec()\fP or \fBpcre[16|32]_dfa_exec()\fP in
+the usual way.
+.P
+However, if you passed a pointer to custom character tables when the pattern
+was compiled (the \fItableptr\fP argument of \fBpcre[16|32]_compile()\fP), you
+must now pass a similar pointer to \fBpcre[16|32]_exec()\fP or
+\fBpcre[16|32]_dfa_exec()\fP, because the value saved with the compiled pattern
+will obviously be nonsense. A field in a \fBpcre[16|32]_extra()\fP block is used
+to pass this data, as described in the
+.\" HTML 
+.\" 
+section on matching a pattern
+.\"
+in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation.
+.P
+\fBWarning:\fP The tables that \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP use
+must be the same as those that were used when the pattern was compiled. If this
+is not the case, the behaviour is undefined.
+.P
+If you did not provide custom character tables when the pattern was compiled,
+the pointer in the compiled pattern is NULL, which causes the matching
+functions to use PCRE's internal tables. Thus, you do not need to take any
+special action at run time in this case.
+.P
+If you saved study data with the compiled pattern, you need to create your own
+\fBpcre[16|32]_extra\fP data block and set the \fIstudy_data\fP field to point
+to the reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in
+the \fIflags\fP field to indicate that study data is present. Then pass the
+\fBpcre[16|32]_extra\fP block to the matching function in the usual way. If the
+pattern was studied for just-in-time optimization, that data cannot be saved,
+and so is lost by a save/restore cycle.
+.
+.
+.SH "COMPATIBILITY WITH DIFFERENT PCRE RELEASES"
+.rs
+.sp
+In general, it is safest to recompile all saved patterns when you update to a
+new PCRE release, though not all updates actually require this.
+.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 12 November 2013
+Copyright (c) 1997-2013 University of Cambridge.
+.fi
diff --git a/doc/pcresample.3 b/doc/pcresample.3
new file mode 100644
index 0000000..d7fe7ec
--- /dev/null
+++ b/doc/pcresample.3
@@ -0,0 +1,99 @@
+.TH PCRESAMPLE 3 "10 January 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "PCRE SAMPLE PROGRAM"
+.rs
+.sp
+A simple, complete demonstration program, to get you started with using PCRE,
+is supplied in the file \fIpcredemo.c\fP in the PCRE distribution. A listing of
+this program is given in the
+.\" HREF
+\fBpcredemo\fP
+.\"
+documentation. If you do not have a copy of the PCRE distribution, you can save
+this listing to re-create \fIpcredemo.c\fP.
+.P
+The demonstration program, which uses the original PCRE 8-bit library, compiles
+the regular expression that is its first argument, and matches it against the
+subject string in its second argument. No PCRE options are set, and default
+character tables are used. If matching succeeds, the program outputs the
+portion of the subject that matched, together with the contents of any captured
+substrings.
+.P
+If the -g option is given on the command line, the program then goes on to
+check for further matches of the same regular expression in the same subject
+string. The logic is a little bit tricky because of the possibility of matching
+an empty string. Comments in the code explain what is going on.
+.P
+If PCRE is installed in the standard include and library directories for your
+operating system, you should be able to compile the demonstration program using
+this command:
+.sp
+  gcc -o pcredemo pcredemo.c -lpcre
+.sp
+If PCRE is installed elsewhere, you may need to add additional options to the
+command line. For example, on a Unix-like system that has PCRE installed in
+\fI/usr/local\fP, you can compile the demonstration program using a command
+like this:
+.sp
+.\" JOINSH
+  gcc -o pcredemo -I/usr/local/include pcredemo.c \e
+      -L/usr/local/lib -lpcre
+.sp
+In a Windows environment, if you want to statically link the program against a
+non-dll \fBpcre.a\fP file, you must uncomment the line that defines PCRE_STATIC
+before including \fBpcre.h\fP, because otherwise the \fBpcre_malloc()\fP and
+\fBpcre_free()\fP exported functions will be declared
+\fB__declspec(dllimport)\fP, with unwanted results.
+.P
+Once you have compiled and linked the demonstration program, you can run simple
+tests like this:
+.sp
+  ./pcredemo 'cat|dog' 'the cat sat on the mat'
+  ./pcredemo -g 'cat|dog' 'the dog sat on the cat'
+.sp
+Note that there is a much more comprehensive test program, called
+.\" HREF
+\fBpcretest\fP,
+.\"
+which supports many more facilities for testing regular expressions and both
+PCRE libraries. The
+.\" HREF
+\fBpcredemo\fP
+.\"
+program is provided as a simple coding example.
+.P
+If you try to run
+.\" HREF
+\fBpcredemo\fP
+.\"
+when PCRE is not installed in the standard library directory, you may get an
+error like this on some operating systems (e.g. Solaris):
+.sp
+  ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory
+.sp
+This is caused by the way shared library support works on those systems. You
+need to add
+.sp
+  -R/usr/local/lib
+.sp
+(for example) to the compile command to get round this problem.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 10 January 2012
+Copyright (c) 1997-2012 University of Cambridge.
+.fi
diff --git a/doc/pcrestack.3 b/doc/pcrestack.3
new file mode 100644
index 0000000..798f0bc
--- /dev/null
+++ b/doc/pcrestack.3
@@ -0,0 +1,215 @@
+.TH PCRESTACK 3 "24 June 2012" "PCRE 8.30"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "PCRE DISCUSSION OF STACK USAGE"
+.rs
+.sp
+When you call \fBpcre[16|32]_exec()\fP, it makes use of an internal function
+called \fBmatch()\fP. This calls itself recursively at branch points in the
+pattern, in order to remember the state of the match so that it can back up and
+try a different alternative if the first one fails. As matching proceeds deeper
+and deeper into the tree of possibilities, the recursion depth increases. The
+\fBmatch()\fP function is also called in other circumstances, for example,
+whenever a parenthesized sub-pattern is entered, and in certain cases of
+repetition.
+.P
+Not all calls of \fBmatch()\fP increase the recursion depth; for an item such
+as a* it may be called several times at the same level, after matching
+different numbers of a's. Furthermore, in a number of cases where the result of
+the recursive call would immediately be passed back as the result of the
+current call (a "tail recursion"), the function is just restarted instead.
+.P
+The above comments apply when \fBpcre[16|32]_exec()\fP is run in its normal
+interpretive manner. If the pattern was studied with the
+PCRE_STUDY_JIT_COMPILE option, and just-in-time compiling was successful, and
+the options passed to \fBpcre[16|32]_exec()\fP were not incompatible, the matching
+process uses the JIT-compiled code instead of the \fBmatch()\fP function. In
+this case, the memory requirements are handled entirely differently. See the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation for details.
+.P
+The \fBpcre[16|32]_dfa_exec()\fP function operates in an entirely different way,
+and uses recursion only when there is a regular expression recursion or
+subroutine call in the pattern. This includes the processing of assertion and
+"once-only" subpatterns, which are handled like subroutine calls. Normally,
+these are never very deep, and the limit on the complexity of
+\fBpcre[16|32]_dfa_exec()\fP is controlled by the amount of workspace it is given.
+However, it is possible to write patterns with runaway infinite recursions;
+such patterns will cause \fBpcre[16|32]_dfa_exec()\fP to run out of stack. At
+present, there is no protection against this.
+.P
+The comments that follow do NOT apply to \fBpcre[16|32]_dfa_exec()\fP; they are
+relevant only for \fBpcre[16|32]_exec()\fP without the JIT optimization.
+.
+.
+.SS "Reducing \fBpcre[16|32]_exec()\fP's stack usage"
+.rs
+.sp
+Each time that \fBmatch()\fP is actually called recursively, it uses memory
+from the process stack. For certain kinds of pattern and data, very large
+amounts of stack may be needed, despite the recognition of "tail recursion".
+You can often reduce the amount of recursion, and therefore the amount of stack
+used, by modifying the pattern that is being matched. Consider, for example,
+this pattern:
+.sp
+  ([^<]|<(?!inet))+
+.sp
+It matches from wherever it starts until it encounters "
+.\" 
+section on extra data for \fBpcre[16|32]_exec()\fP
+.\"
+in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation.
+.P
+As a very rough rule of thumb, you should reckon on about 500 bytes per
+recursion. Thus, if you want to limit your stack usage to 8Mb, you should set
+the limit at 16000 recursions. A 64Mb stack, on the other hand, can support
+around 128000 recursions.
+.P
+In Unix-like environments, the \fBpcretest\fP test program has a command line
+option (\fB-S\fP) that can be used to increase the size of its stack. As long
+as the stack is large enough, another option (\fB-M\fP) can be used to find the
+smallest limits that allow a particular pattern to match a given subject
+string. This is done by calling \fBpcre[16|32]_exec()\fP repeatedly with different
+limits.
+.
+.
+.SS "Obtaining an estimate of stack usage"
+.rs
+.sp
+The actual amount of stack used per recursion can vary quite a lot, depending
+on the compiler that was used to build PCRE and the optimization or debugging
+options that were set for it. The rule of thumb value of 500 bytes mentioned
+above may be larger or smaller than what is actually needed. A better
+approximation can be obtained by running this command:
+.sp
+  pcretest -m -C
+.sp
+The \fB-C\fP option causes \fBpcretest\fP to output information about the
+options with which PCRE was compiled. When \fB-m\fP is also given (before
+\fB-C\fP), information about stack use is given in a line like this:
+.sp
+  Match recursion uses stack: approximate frame size = 640 bytes
+.sp
+The value is approximate because some recursions need a bit more (up to perhaps
+16 more bytes).
+.P
+If the above command is given when PCRE is compiled to use the heap instead of
+the stack for recursion, the value that is output is the size of each block
+that is obtained from the heap.
+.
+.
+.SS "Changing stack size in Unix-like systems"
+.rs
+.sp
+In Unix-like environments, there is not often a problem with the stack unless
+very long strings are involved, though the default limit on stack size varies
+from system to system. Values from 8Mb to 64Mb are common. You can find your
+default limit by running the command:
+.sp
+  ulimit -s
+.sp
+Unfortunately, the effect of running out of stack is often SIGSEGV, though
+sometimes a more explicit error message is given. You can normally increase the
+limit on stack size by code such as this:
+.sp
+  struct rlimit rlim;
+  getrlimit(RLIMIT_STACK, &rlim);
+  rlim.rlim_cur = 100*1024*1024;
+  setrlimit(RLIMIT_STACK, &rlim);
+.sp
+This reads the current limits (soft and hard) using \fBgetrlimit()\fP, then
+attempts to increase the soft limit to 100Mb using \fBsetrlimit()\fP. You must
+do this before calling \fBpcre[16|32]_exec()\fP.
+.
+.
+.SS "Changing stack size in Mac OS X"
+.rs
+.sp
+Using \fBsetrlimit()\fP, as described above, should also work on Mac OS X. It
+is also possible to set a stack size when linking a program. There is a
+discussion about stack sizes in Mac OS X at this web site:
+.\" HTML 
+.\" 
+http://developer.apple.com/qa/qa2005/qa1419.html.
+.\"
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 24 June 2012
+Copyright (c) 1997-2012 University of Cambridge.
+.fi
diff --git a/doc/pcresyntax.3 b/doc/pcresyntax.3
new file mode 100644
index 0000000..fd878da
--- /dev/null
+++ b/doc/pcresyntax.3
@@ -0,0 +1,517 @@
+.TH PCRESYNTAX 3 "08 January 2014" "PCRE 8.35"
+.SH NAME
+PCRE - Perl-compatible regular expressions
+.SH "PCRE REGULAR EXPRESSION SYNTAX SUMMARY"
+.rs
+.sp
+The full syntax and semantics of the regular expressions that are supported by
+PCRE are described in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+documentation. This document contains a quick-reference summary of the syntax.
+.
+.
+.SH "QUOTING"
+.rs
+.sp
+  \ex         where x is non-alphanumeric is a literal x
+  \eQ...\eE    treat enclosed characters as literal
+.
+.
+.SH "CHARACTERS"
+.rs
+.sp
+  \ea         alarm, that is, the BEL character (hex 07)
+  \ecx        "control-x", where x is any ASCII character
+  \ee         escape (hex 1B)
+  \ef         form feed (hex 0C)
+  \en         newline (hex 0A)
+  \er         carriage return (hex 0D)
+  \et         tab (hex 09)
+  \e0dd       character with octal code 0dd
+  \eddd       character with octal code ddd, or backreference
+  \eo{ddd..}  character with octal code ddd..
+  \exhh       character with hex code hh
+  \ex{hhh..}  character with hex code hhh..
+.sp
+Note that \e0dd is always an octal code, and that \e8 and \e9 are the literal
+characters "8" and "9".
+.
+.
+.SH "CHARACTER TYPES"
+.rs
+.sp
+  .          any character except newline;
+               in dotall mode, any character whatsoever
+  \eC         one data unit, even in UTF mode (best avoided)
+  \ed         a decimal digit
+  \eD         a character that is not a decimal digit
+  \eh         a horizontal white space character
+  \eH         a character that is not a horizontal white space character
+  \eN         a character that is not a newline
+  \ep{\fIxx\fP}     a character with the \fIxx\fP property
+  \eP{\fIxx\fP}     a character without the \fIxx\fP property
+  \eR         a newline sequence
+  \es         a white space character
+  \eS         a character that is not a white space character
+  \ev         a vertical white space character
+  \eV         a character that is not a vertical white space character
+  \ew         a "word" character
+  \eW         a "non-word" character
+  \eX         a Unicode extended grapheme cluster
+.sp
+By default, \ed, \es, and \ew match only ASCII characters, even in UTF-8 mode
+or in the 16- bit and 32-bit libraries. However, if locale-specific matching is
+happening, \es and \ew may also match characters with code points in the range
+128-255. If the PCRE_UCP option is set, the behaviour of these escape sequences
+is changed to use Unicode properties and they match many more characters.
+.
+.
+.SH "GENERAL CATEGORY PROPERTIES FOR \ep and \eP"
+.rs
+.sp
+  C          Other
+  Cc         Control
+  Cf         Format
+  Cn         Unassigned
+  Co         Private use
+  Cs         Surrogate
+.sp
+  L          Letter
+  Ll         Lower case letter
+  Lm         Modifier letter
+  Lo         Other letter
+  Lt         Title case letter
+  Lu         Upper case letter
+  L&         Ll, Lu, or Lt
+.sp
+  M          Mark
+  Mc         Spacing mark
+  Me         Enclosing mark
+  Mn         Non-spacing mark
+.sp
+  N          Number
+  Nd         Decimal number
+  Nl         Letter number
+  No         Other number
+.sp
+  P          Punctuation
+  Pc         Connector punctuation
+  Pd         Dash punctuation
+  Pe         Close punctuation
+  Pf         Final punctuation
+  Pi         Initial punctuation
+  Po         Other punctuation
+  Ps         Open punctuation
+.sp
+  S          Symbol
+  Sc         Currency symbol
+  Sk         Modifier symbol
+  Sm         Mathematical symbol
+  So         Other symbol
+.sp
+  Z          Separator
+  Zl         Line separator
+  Zp         Paragraph separator
+  Zs         Space separator
+.
+.
+.SH "PCRE SPECIAL CATEGORY PROPERTIES FOR \ep and \eP"
+.rs
+.sp
+  Xan        Alphanumeric: union of properties L and N
+  Xps        POSIX space: property Z or tab, NL, VT, FF, CR
+  Xsp        Perl space: property Z or tab, NL, VT, FF, CR
+  Xuc        Univerally-named character: one that can be
+               represented by a Universal Character Name
+  Xwd        Perl word: property Xan or underscore
+.sp
+Perl and POSIX space are now the same. Perl added VT to its space character set
+at release 5.18 and PCRE changed at release 8.34.
+.
+.
+.SH "SCRIPT NAMES FOR \ep AND \eP"
+.rs
+.sp
+Arabic,
+Armenian,
+Avestan,
+Balinese,
+Bamum,
+Batak,
+Bengali,
+Bopomofo,
+Brahmi,
+Braille,
+Buginese,
+Buhid,
+Canadian_Aboriginal,
+Carian,
+Chakma,
+Cham,
+Cherokee,
+Common,
+Coptic,
+Cuneiform,
+Cypriot,
+Cyrillic,
+Deseret,
+Devanagari,
+Egyptian_Hieroglyphs,
+Ethiopic,
+Georgian,
+Glagolitic,
+Gothic,
+Greek,
+Gujarati,
+Gurmukhi,
+Han,
+Hangul,
+Hanunoo,
+Hebrew,
+Hiragana,
+Imperial_Aramaic,
+Inherited,
+Inscriptional_Pahlavi,
+Inscriptional_Parthian,
+Javanese,
+Kaithi,
+Kannada,
+Katakana,
+Kayah_Li,
+Kharoshthi,
+Khmer,
+Lao,
+Latin,
+Lepcha,
+Limbu,
+Linear_B,
+Lisu,
+Lycian,
+Lydian,
+Malayalam,
+Mandaic,
+Meetei_Mayek,
+Meroitic_Cursive,
+Meroitic_Hieroglyphs,
+Miao,
+Mongolian,
+Myanmar,
+New_Tai_Lue,
+Nko,
+Ogham,
+Old_Italic,
+Old_Persian,
+Old_South_Arabian,
+Old_Turkic,
+Ol_Chiki,
+Oriya,
+Osmanya,
+Phags_Pa,
+Phoenician,
+Rejang,
+Runic,
+Samaritan,
+Saurashtra,
+Sharada,
+Shavian,
+Sinhala,
+Sora_Sompeng,
+Sundanese,
+Syloti_Nagri,
+Syriac,
+Tagalog,
+Tagbanwa,
+Tai_Le,
+Tai_Tham,
+Tai_Viet,
+Takri,
+Tamil,
+Telugu,
+Thaana,
+Thai,
+Tibetan,
+Tifinagh,
+Ugaritic,
+Vai,
+Yi.
+.
+.
+.SH "CHARACTER CLASSES"
+.rs
+.sp
+  [...]       positive character class
+  [^...]      negative character class
+  [x-y]       range (can be used for hex characters)
+  [[:xxx:]]   positive POSIX named set
+  [[:^xxx:]]  negative POSIX named set
+.sp
+  alnum       alphanumeric
+  alpha       alphabetic
+  ascii       0-127
+  blank       space or tab
+  cntrl       control character
+  digit       decimal digit
+  graph       printing, excluding space
+  lower       lower case letter
+  print       printing, including space
+  punct       printing, excluding alphanumeric
+  space       white space
+  upper       upper case letter
+  word        same as \ew
+  xdigit      hexadecimal digit
+.sp
+In PCRE, POSIX character set names recognize only ASCII characters by default,
+but some of them use Unicode properties if PCRE_UCP is set. You can use
+\eQ...\eE inside a character class.
+.
+.
+.SH "QUANTIFIERS"
+.rs
+.sp
+  ?           0 or 1, greedy
+  ?+          0 or 1, possessive
+  ??          0 or 1, lazy
+  *           0 or more, greedy
+  *+          0 or more, possessive
+  *?          0 or more, lazy
+  +           1 or more, greedy
+  ++          1 or more, possessive
+  +?          1 or more, lazy
+  {n}         exactly n
+  {n,m}       at least n, no more than m, greedy
+  {n,m}+      at least n, no more than m, possessive
+  {n,m}?      at least n, no more than m, lazy
+  {n,}        n or more, greedy
+  {n,}+       n or more, possessive
+  {n,}?       n or more, lazy
+.
+.
+.SH "ANCHORS AND SIMPLE ASSERTIONS"
+.rs
+.sp
+  \eb          word boundary
+  \eB          not a word boundary
+  ^           start of subject
+               also after internal newline in multiline mode
+  \eA          start of subject
+  $           end of subject
+               also before newline at end of subject
+               also before internal newline in multiline mode
+  \eZ          end of subject
+               also before newline at end of subject
+  \ez          end of subject
+  \eG          first matching position in subject
+.
+.
+.SH "MATCH POINT RESET"
+.rs
+.sp
+  \eK          reset start of match
+.sp
+\eK is honoured in positive assertions, but ignored in negative ones.
+.
+.
+.SH "ALTERNATION"
+.rs
+.sp
+  expr|expr|expr...
+.
+.
+.SH "CAPTURING"
+.rs
+.sp
+  (...)           capturing group
+  (?...)    named capturing group (Perl)
+  (?'name'...)    named capturing group (Perl)
+  (?P...)   named capturing group (Python)
+  (?:...)         non-capturing group
+  (?|...)         non-capturing group; reset group numbers for
+                   capturing groups in each alternative
+.
+.
+.SH "ATOMIC GROUPS"
+.rs
+.sp
+  (?>...)         atomic, non-capturing group
+.
+.
+.
+.
+.SH "COMMENT"
+.rs
+.sp
+  (?#....)        comment (not nestable)
+.
+.
+.SH "OPTION SETTING"
+.rs
+.sp
+  (?i)            caseless
+  (?J)            allow duplicate names
+  (?m)            multiline
+  (?s)            single line (dotall)
+  (?U)            default ungreedy (lazy)
+  (?x)            extended (ignore white space)
+  (?-...)         unset option(s)
+.sp
+The following are recognized only at the very start of a pattern or after one
+of the newline or \eR options with similar syntax. More than one of them may
+appear.
+.sp
+  (*LIMIT_MATCH=d) set the match limit to d (decimal number)
+  (*LIMIT_RECURSION=d) set the recursion limit to d (decimal number)
+  (*NO_AUTO_POSSESS) no auto-possessification (PCRE_NO_AUTO_POSSESS)
+  (*NO_START_OPT) no start-match optimization (PCRE_NO_START_OPTIMIZE)
+  (*UTF8)         set UTF-8 mode: 8-bit library (PCRE_UTF8)
+  (*UTF16)        set UTF-16 mode: 16-bit library (PCRE_UTF16)
+  (*UTF32)        set UTF-32 mode: 32-bit library (PCRE_UTF32)
+  (*UTF)          set appropriate UTF mode for the library in use
+  (*UCP)          set PCRE_UCP (use Unicode properties for \ed etc)
+.sp
+Note that LIMIT_MATCH and LIMIT_RECURSION can only reduce the value of the
+limits set by the caller of pcre_exec(), not increase them.
+.
+.
+.SH "NEWLINE CONVENTION"
+.rs
+.sp
+These are recognized only at the very start of the pattern or after option
+settings with a similar syntax.
+.sp
+  (*CR)           carriage return only
+  (*LF)           linefeed only
+  (*CRLF)         carriage return followed by linefeed
+  (*ANYCRLF)      all three of the above
+  (*ANY)          any Unicode newline sequence
+.
+.
+.SH "WHAT \eR MATCHES"
+.rs
+.sp
+These are recognized only at the very start of the pattern or after option
+setting with a similar syntax.
+.sp
+  (*BSR_ANYCRLF)  CR, LF, or CRLF
+  (*BSR_UNICODE)  any Unicode newline sequence
+.
+.
+.SH "LOOKAHEAD AND LOOKBEHIND ASSERTIONS"
+.rs
+.sp
+  (?=...)         positive look ahead
+  (?!...)         negative look ahead
+  (?<=...)        positive look behind
+  (?        reference by name (Perl)
+  \ek'name'        reference by name (Perl)
+  \eg{name}        reference by name (Perl)
+  \ek{name}        reference by name (.NET)
+  (?P=name)       reference by name (Python)
+.
+.
+.SH "SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)"
+.rs
+.sp
+  (?R)            recurse whole pattern
+  (?n)            call subpattern by absolute number
+  (?+n)           call subpattern by relative number
+  (?-n)           call subpattern by relative number
+  (?&name)        call subpattern by name (Perl)
+  (?P>name)       call subpattern by name (Python)
+  \eg        call subpattern by name (Oniguruma)
+  \eg'name'        call subpattern by name (Oniguruma)
+  \eg           call subpattern by absolute number (Oniguruma)
+  \eg'n'           call subpattern by absolute number (Oniguruma)
+  \eg<+n>          call subpattern by relative number (PCRE extension)
+  \eg'+n'          call subpattern by relative number (PCRE extension)
+  \eg<-n>          call subpattern by relative number (PCRE extension)
+  \eg'-n'          call subpattern by relative number (PCRE extension)
+.
+.
+.SH "CONDITIONAL PATTERNS"
+.rs
+.sp
+  (?(condition)yes-pattern)
+  (?(condition)yes-pattern|no-pattern)
+.sp
+  (?(n)...        absolute reference condition
+  (?(+n)...       relative reference condition
+  (?(-n)...       relative reference condition
+  (?()...   named reference condition (Perl)
+  (?('name')...   named reference condition (Perl)
+  (?(name)...     named reference condition (PCRE)
+  (?(R)...        overall recursion condition
+  (?(Rn)...       specific group recursion condition
+  (?(R&name)...   specific recursion condition
+  (?(DEFINE)...   define subpattern for reference
+  (?(assert)...   assertion condition
+.
+.
+.SH "BACKTRACKING CONTROL"
+.rs
+.sp
+The following act immediately they are reached:
+.sp
+  (*ACCEPT)       force successful match
+  (*FAIL)         force backtrack; synonym (*F)
+  (*MARK:NAME)    set name to be passed back; synonym (*:NAME)
+.sp
+The following act only when a subsequent match failure causes a backtrack to
+reach them. They all force a match failure, but they differ in what happens
+afterwards. Those that advance the start-of-match point do so only if the
+pattern is not anchored.
+.sp
+  (*COMMIT)       overall failure, no advance of starting point
+  (*PRUNE)        advance to next starting character
+  (*PRUNE:NAME)   equivalent to (*MARK:NAME)(*PRUNE)
+  (*SKIP)         advance to current matching position
+  (*SKIP:NAME)    advance to position corresponding to an earlier
+                  (*MARK:NAME); if not found, the (*SKIP) is ignored
+  (*THEN)         local failure, backtrack to next alternation
+  (*THEN:NAME)    equivalent to (*MARK:NAME)(*THEN)
+.
+.
+.SH "CALLOUTS"
+.rs
+.sp
+  (?C)      callout
+  (?Cn)     callout with data n
+.
+.
+.SH "SEE ALSO"
+.rs
+.sp
+\fBpcrepattern\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3),
+\fBpcrematching\fP(3), \fBpcre\fP(3).
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 08 January 2014
+Copyright (c) 1997-2014 University of Cambridge.
+.fi
diff --git a/doc/pcretest.1 b/doc/pcretest.1
new file mode 100644
index 0000000..92640da
--- /dev/null
+++ b/doc/pcretest.1
@@ -0,0 +1,1156 @@
+.TH PCRETEST 1 "09 February 2014" "PCRE 8.35"
+.SH NAME
+pcretest - a program for testing Perl-compatible regular expressions.
+.SH SYNOPSIS
+.rs
+.sp
+.B pcretest "[options] [input file [output file]]"
+.sp
+\fBpcretest\fP was written as a test program for the PCRE regular expression
+library itself, but it can also be used for experimenting with regular
+expressions. This document describes the features of the test program; for
+details of the regular expressions themselves, see the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+documentation. For details of the PCRE library function calls and their
+options, see the
+.\" HREF
+\fBpcreapi\fP
+.\"
+,
+.\" HREF
+\fBpcre16\fP
+and
+.\" HREF
+\fBpcre32\fP
+.\"
+documentation.
+.P
+The input for \fBpcretest\fP is a sequence of regular expression patterns and
+strings to be matched, as described below. The output shows the result of each
+match. Options on the command line and the patterns control PCRE options and
+exactly what is output.
+.P
+As PCRE has evolved, it has acquired many different features, and as a result,
+\fBpcretest\fP now has rather a lot of obscure options for testing every
+possible feature. Some of these options are specifically designed for use in
+conjunction with the test script and data files that are distributed as part of
+PCRE, and are unlikely to be of use otherwise. They are all documented here,
+but without much justification.
+.
+.
+.SH "INPUT DATA FORMAT"
+.rs
+.sp
+Input to \fBpcretest\fP is processed line by line, either by calling the C
+library's \fBfgets()\fP function, or via the \fBlibreadline\fP library (see
+below). In Unix-like environments, \fBfgets()\fP treats any bytes other than
+newline as data characters. However, in some Windows environments character 26
+(hex 1A) causes an immediate end of file, and no further data is read. For
+maximum portability, therefore, it is safest to use only ASCII characters in
+\fBpcretest\fP input files.
+.
+.
+.SH "PCRE's 8-BIT, 16-BIT AND 32-BIT LIBRARIES"
+.rs
+.sp
+From release 8.30, two separate PCRE libraries can be built. The original one
+supports 8-bit character strings, whereas the newer 16-bit library supports
+character strings encoded in 16-bit units. From release 8.32, a third library
+can be built, supporting character strings encoded in 32-bit units. The
+\fBpcretest\fP program can be used to test all three libraries. However, it is
+itself still an 8-bit program, reading 8-bit input and writing 8-bit output.
+When testing the 16-bit or 32-bit library, the patterns and data strings are
+converted to 16- or 32-bit format before being passed to the PCRE library
+functions. Results are converted to 8-bit for output.
+.P
+References to functions and structures of the form \fBpcre[16|32]_xx\fP below
+mean "\fBpcre_xx\fP when using the 8-bit library, \fBpcre16_xx\fP when using
+the 16-bit library, or \fBpcre32_xx\fP when using the 32-bit library".
+.
+.
+.SH "COMMAND LINE OPTIONS"
+.rs
+.TP 10
+\fB-8\fP
+If both the 8-bit library has been built, this option causes the 8-bit library
+to be used (which is the default); if the 8-bit library has not been built,
+this option causes an error.
+.TP 10
+\fB-16\fP
+If both the 8-bit or the 32-bit, and the 16-bit libraries have been built, this
+option causes the 16-bit library to be used. If only the 16-bit library has been
+built, this is the default (so has no effect). If only the 8-bit or the 32-bit
+library has been built, this option causes an error.
+.TP 10
+\fB-32\fP
+If both the 8-bit or the 16-bit, and the 32-bit libraries have been built, this
+option causes the 32-bit library to be used. If only the 32-bit library has been
+built, this is the default (so has no effect). If only the 8-bit or the 16-bit
+library has been built, this option causes an error.
+.TP 10
+\fB-b\fP
+Behave as if each pattern has the \fB/B\fP (show byte code) modifier; the
+internal form is output after compilation.
+.TP 10
+\fB-C\fP
+Output the version number of the PCRE library, and all available information
+about the optional features that are included, and then exit with zero exit
+code. All other options are ignored.
+.TP 10
+\fB-C\fP \fIoption\fP
+Output information about a specific build-time option, then exit. This
+functionality is intended for use in scripts such as \fBRunTest\fP. The
+following options output the value and set the exit code as indicated:
+.sp
+  ebcdic-nl  the code for LF (= NL) in an EBCDIC environment:
+               0x15 or 0x25
+               0 if used in an ASCII environment
+               exit code is always 0
+  linksize   the configured internal link size (2, 3, or 4)
+               exit code is set to the link size
+  newline    the default newline setting:
+               CR, LF, CRLF, ANYCRLF, or ANY
+               exit code is always 0
+  bsr        the default setting for what \eR matches:
+               ANYCRLF or ANY
+               exit code is always 0
+.sp
+The following options output 1 for true or 0 for false, and set the exit code
+to the same value:
+.sp
+  ebcdic     compiled for an EBCDIC environment
+  jit        just-in-time support is available
+  pcre16     the 16-bit library was built
+  pcre32     the 32-bit library was built
+  pcre8      the 8-bit library was built
+  ucp        Unicode property support is available
+  utf        UTF-8 and/or UTF-16 and/or UTF-32 support
+               is available
+.sp
+If an unknown option is given, an error message is output; the exit code is 0.
+.TP 10
+\fB-d\fP
+Behave as if each pattern has the \fB/D\fP (debug) modifier; the internal
+form and information about the compiled pattern is output after compilation;
+\fB-d\fP is equivalent to \fB-b -i\fP.
+.TP 10
+\fB-dfa\fP
+Behave as if each data line contains the \eD escape sequence; this causes the
+alternative matching function, \fBpcre[16|32]_dfa_exec()\fP, to be used instead
+of the standard \fBpcre[16|32]_exec()\fP function (more detail is given below).
+.TP 10
+\fB-help\fP
+Output a brief summary these options and then exit.
+.TP 10
+\fB-i\fP
+Behave as if each pattern has the \fB/I\fP modifier; information about the
+compiled pattern is given after compilation.
+.TP 10
+\fB-M\fP
+Behave as if each data line contains the \eM escape sequence; this causes
+PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
+calling \fBpcre[16|32]_exec()\fP repeatedly with different limits.
+.TP 10
+\fB-m\fP
+Output the size of each compiled pattern after it has been compiled. This is
+equivalent to adding \fB/M\fP to each regular expression. The size is given in
+bytes for both libraries.
+.TP 10
+\fB-O\fP
+Behave as if each pattern has the \fB/O\fP modifier, that is disable
+auto-possessification for all patterns.
+.TP 10
+\fB-o\fP \fIosize\fP
+Set the number of elements in the output vector that is used when calling
+\fBpcre[16|32]_exec()\fP or \fBpcre[16|32]_dfa_exec()\fP to be \fIosize\fP. The
+default value is 45, which is enough for 14 capturing subexpressions for
+\fBpcre[16|32]_exec()\fP or 22 different matches for
+\fBpcre[16|32]_dfa_exec()\fP.
+The vector size can be changed for individual matching calls by including \eO
+in the data line (see below).
+.TP 10
+\fB-p\fP
+Behave as if each pattern has the \fB/P\fP modifier; the POSIX wrapper API is
+used to call PCRE. None of the other options has any effect when \fB-p\fP is
+set. This option can be used only with the 8-bit library.
+.TP 10
+\fB-q\fP
+Do not output the version number of \fBpcretest\fP at the start of execution.
+.TP 10
+\fB-S\fP \fIsize\fP
+On Unix-like systems, set the size of the run-time stack to \fIsize\fP
+megabytes.
+.TP 10
+\fB-s\fP or \fB-s+\fP
+Behave as if each pattern has the \fB/S\fP modifier; in other words, force each
+pattern to be studied. If \fB-s+\fP is used, all the JIT compile options are
+passed to \fBpcre[16|32]_study()\fP, causing just-in-time optimization to be set
+up if it is available, for both full and partial matching. Specific JIT compile
+options can be selected by following \fB-s+\fP with a digit in the range 1 to
+7, which selects the JIT compile modes as follows:
+.sp
+  1  normal match only
+  2  soft partial match only
+  3  normal match and soft partial match
+  4  hard partial match only
+  6  soft and hard partial match
+  7  all three modes (default)
+.sp
+If \fB-s++\fP is used instead of \fB-s+\fP (with or without a following digit),
+the text "(JIT)" is added to the first output line after a match or no match
+when JIT-compiled code was actually used.
+.sp
+Note that there are pattern options that can override \fB-s\fP, either
+specifying no studying at all, or suppressing JIT compilation.
+.sp
+If the \fB/I\fP or \fB/D\fP option is present on a pattern (requesting output
+about the compiled pattern), information about the result of studying is not
+included when studying is caused only by \fB-s\fP and neither \fB-i\fP nor
+\fB-d\fP is present on the command line. This behaviour means that the output
+from tests that are run with and without \fB-s\fP should be identical, except
+when options that output information about the actual running of a match are
+set.
+.sp
+The \fB-M\fP, \fB-t\fP, and \fB-tm\fP options, which give information about
+resources used, are likely to produce different output with and without
+\fB-s\fP. Output may also differ if the \fB/C\fP option is present on an
+individual pattern. This uses callouts to trace the the matching process, and
+this may be different between studied and non-studied patterns. If the pattern
+contains (*MARK) items there may also be differences, for the same reason. The
+\fB-s\fP command line option can be overridden for specific patterns that
+should never be studied (see the \fB/S\fP pattern modifier below).
+.TP 10
+\fB-t\fP
+Run each compile, study, and match many times with a timer, and output the
+resulting times per compile, study, or match (in milliseconds). Do not set
+\fB-m\fP with \fB-t\fP, because you will then get the size output a zillion
+times, and the timing will be distorted. You can control the number of
+iterations that are used for timing by following \fB-t\fP with a number (as a
+separate item on the command line). For example, "-t 1000" iterates 1000 times.
+The default is to iterate 500000 times.
+.TP 10
+\fB-tm\fP
+This is like \fB-t\fP except that it times only the matching phase, not the
+compile or study phases.
+.TP 10
+\fB-T\fP \fB-TM\fP
+These behave like \fB-t\fP and \fB-tm\fP, but in addition, at the end of a run,
+the total times for all compiles, studies, and matches are output.
+.
+.
+.SH DESCRIPTION
+.rs
+.sp
+If \fBpcretest\fP is given two filename arguments, it reads from the first and
+writes to the second. If it is given only one filename argument, it reads from
+that file and writes to stdout. Otherwise, it reads from stdin and writes to
+stdout, and prompts for each line of input, using "re>" to prompt for regular
+expressions, and "data>" to prompt for data lines.
+.P
+When \fBpcretest\fP is built, a configuration option can specify that it should
+be linked with the \fBlibreadline\fP library. When this is done, if the input
+is from a terminal, it is read using the \fBreadline()\fP function. This
+provides line-editing and history facilities. The output from the \fB-help\fP
+option states whether or not \fBreadline()\fP will be used.
+.P
+The program handles any number of sets of input on a single input file. Each
+set starts with a regular expression, and continues with any number of data
+lines to be matched against that pattern.
+.P
+Each data line is matched separately and independently. If you want to do
+multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
+etc., depending on the newline setting) in a single line of input to encode the
+newline sequences. There is no limit on the length of data lines; the input
+buffer is automatically extended if it is too small.
+.P
+An empty line signals the end of the data lines, at which point a new regular
+expression is read. The regular expressions are given enclosed in any
+non-alphanumeric delimiters other than backslash, for example:
+.sp
+  /(a|bc)x+yz/
+.sp
+White space before the initial delimiter is ignored. A regular expression may
+be continued over several input lines, in which case the newline characters are
+included within it. It is possible to include the delimiter within the pattern
+by escaping it, for example
+.sp
+  /abc\e/def/
+.sp
+If you do so, the escape and the delimiter form part of the pattern, but since
+delimiters are always non-alphanumeric, this does not affect its interpretation.
+If the terminating delimiter is immediately followed by a backslash, for
+example,
+.sp
+  /abc/\e
+.sp
+then a backslash is added to the end of the pattern. This is done to provide a
+way of testing the error condition that arises if a pattern finishes with a
+backslash, because
+.sp
+  /abc\e/
+.sp
+is interpreted as the first line of a pattern that starts with "abc/", causing
+pcretest to read the next line as a continuation of the regular expression.
+.
+.
+.SH "PATTERN MODIFIERS"
+.rs
+.sp
+A pattern may be followed by any number of modifiers, which are mostly single
+characters, though some of these can be qualified by further characters.
+Following Perl usage, these are referred to below as, for example, "the
+\fB/i\fP modifier", even though the delimiter of the pattern need not always be
+a slash, and no slash is used when writing modifiers. White space may appear
+between the final pattern delimiter and the first modifier, and between the
+modifiers themselves. For reference, here is a complete list of modifiers. They
+fall into several groups that are described in detail in the following
+sections.
+.sp
+  \fB/8\fP              set UTF mode
+  \fB/9\fP              set PCRE_NEVER_UTF (locks out UTF mode)
+  \fB/?\fP              disable UTF validity check
+  \fB/+\fP              show remainder of subject after match
+  \fB/=\fP              show all captures (not just those that are set)
+.sp
+  \fB/A\fP              set PCRE_ANCHORED
+  \fB/B\fP              show compiled code
+  \fB/C\fP              set PCRE_AUTO_CALLOUT
+  \fB/D\fP              same as \fB/B\fP plus \fB/I\fP
+  \fB/E\fP              set PCRE_DOLLAR_ENDONLY
+  \fB/F\fP              flip byte order in compiled pattern
+  \fB/f\fP              set PCRE_FIRSTLINE
+  \fB/G\fP              find all matches (shorten string)
+  \fB/g\fP              find all matches (use startoffset)
+  \fB/I\fP              show information about pattern
+  \fB/i\fP              set PCRE_CASELESS
+  \fB/J\fP              set PCRE_DUPNAMES
+  \fB/K\fP              show backtracking control names
+  \fB/L\fP              set locale
+  \fB/M\fP              show compiled memory size
+  \fB/m\fP              set PCRE_MULTILINE
+  \fB/N\fP              set PCRE_NO_AUTO_CAPTURE
+  \fB/O\fP              set PCRE_NO_AUTO_POSSESS
+  \fB/P\fP              use the POSIX wrapper
+  \fB/Q\fP              test external stack check function
+  \fB/S\fP              study the pattern after compilation
+  \fB/s\fP              set PCRE_DOTALL
+  \fB/T\fP              select character tables
+  \fB/U\fP              set PCRE_UNGREEDY
+  \fB/W\fP              set PCRE_UCP
+  \fB/X\fP              set PCRE_EXTRA
+  \fB/x\fP              set PCRE_EXTENDED
+  \fB/Y\fP              set PCRE_NO_START_OPTIMIZE
+  \fB/Z\fP              don't show lengths in \fB/B\fP output
+.sp
+  \fB/\fP          set PCRE_NEWLINE_ANY
+  \fB/\fP      set PCRE_NEWLINE_ANYCRLF
+  \fB/\fP           set PCRE_NEWLINE_CR
+  \fB/\fP         set PCRE_NEWLINE_CRLF
+  \fB/\fP           set PCRE_NEWLINE_LF
+  \fB/\fP  set PCRE_BSR_ANYCRLF
+  \fB/\fP  set PCRE_BSR_UNICODE
+  \fB/\fP           set PCRE_JAVASCRIPT_COMPAT
+.sp
+.
+.
+.SS "Perl-compatible modifiers"
+.rs
+.sp
+The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
+PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
+\fBpcre[16|32]_compile()\fP is called. These four modifier letters have the same
+effect as they do in Perl. For example:
+.sp
+  /caseless/i
+.sp
+.
+.
+.SS "Modifiers for other PCRE options"
+.rs
+.sp
+The following table shows additional modifiers for setting PCRE compile-time
+options that do not correspond to anything in Perl:
+.sp
+  \fB/8\fP              PCRE_UTF8           ) when using the 8-bit
+  \fB/?\fP              PCRE_NO_UTF8_CHECK  )   library
+.sp
+  \fB/8\fP              PCRE_UTF16          ) when using the 16-bit
+  \fB/?\fP              PCRE_NO_UTF16_CHECK )   library
+.sp
+  \fB/8\fP              PCRE_UTF32          ) when using the 32-bit
+  \fB/?\fP              PCRE_NO_UTF32_CHECK )   library
+.sp
+  \fB/9\fP              PCRE_NEVER_UTF
+  \fB/A\fP              PCRE_ANCHORED
+  \fB/C\fP              PCRE_AUTO_CALLOUT
+  \fB/E\fP              PCRE_DOLLAR_ENDONLY
+  \fB/f\fP              PCRE_FIRSTLINE
+  \fB/J\fP              PCRE_DUPNAMES
+  \fB/N\fP              PCRE_NO_AUTO_CAPTURE
+  \fB/O\fP              PCRE_NO_AUTO_POSSESS
+  \fB/U\fP              PCRE_UNGREEDY
+  \fB/W\fP              PCRE_UCP
+  \fB/X\fP              PCRE_EXTRA
+  \fB/Y\fP              PCRE_NO_START_OPTIMIZE
+  \fB/\fP          PCRE_NEWLINE_ANY
+  \fB/\fP      PCRE_NEWLINE_ANYCRLF
+  \fB/\fP           PCRE_NEWLINE_CR
+  \fB/\fP         PCRE_NEWLINE_CRLF
+  \fB/\fP           PCRE_NEWLINE_LF
+  \fB/\fP  PCRE_BSR_ANYCRLF
+  \fB/\fP  PCRE_BSR_UNICODE
+  \fB/\fP           PCRE_JAVASCRIPT_COMPAT
+.sp
+The modifiers that are enclosed in angle brackets are literal strings as shown,
+including the angle brackets, but the letters within can be in either case.
+This example sets multiline matching with CRLF as the line ending sequence:
+.sp
+  /^abc/m
+.sp
+As well as turning on the PCRE_UTF8/16/32 option, the \fB/8\fP modifier causes
+all non-printing characters in output strings to be printed using the
+\ex{hh...} notation. Otherwise, those less than 0x100 are output in hex without
+the curly brackets.
+.P
+Full details of the PCRE options are given in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation.
+.
+.
+.SS "Finding all matches in a string"
+.rs
+.sp
+Searching for all possible matches within each subject string can be requested
+by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
+again to search the remainder of the subject string. The difference between
+\fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
+\fBpcre[16|32]_exec()\fP to start searching at a new point within the entire
+string (which is in effect what Perl does), whereas the latter passes over a
+shortened substring. This makes a difference to the matching process if the
+pattern begins with a lookbehind assertion (including \eb or \eB).
+.P
+If any call to \fBpcre[16|32]_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches
+an empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
+PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
+same point. If this second match fails, the start offset is advanced, and the
+normal match is retried. This imitates the way Perl handles such cases when
+using the \fB/g\fP modifier or the \fBsplit()\fP function. Normally, the start
+offset is advanced by one character, but if the newline convention recognizes
+CRLF as a newline, and the current character is CR followed by LF, an advance
+of two is used.
+.
+.
+.SS "Other modifiers"
+.rs
+.sp
+There are yet more modifiers for controlling the way \fBpcretest\fP
+operates.
+.P
+The \fB/+\fP modifier requests that as well as outputting the substring that
+matched the entire pattern, \fBpcretest\fP should in addition output the
+remainder of the subject string. This is useful for tests where the subject
+contains multiple copies of the same substring. If the \fB+\fP modifier appears
+twice, the same action is taken for captured substrings. In each case the
+remainder is output on the following line with a plus character following the
+capture number. Note that this modifier must not immediately follow the /S
+modifier because /S+ and /S++ have other meanings.
+.P
+The \fB/=\fP modifier requests that the values of all potential captured
+parentheses be output after a match. By default, only those up to the highest
+one actually used in the match are output (corresponding to the return code
+from \fBpcre[16|32]_exec()\fP). Values in the offsets vector corresponding to
+higher numbers should be set to -1, and these are output as "". This
+modifier gives a way of checking that this is happening.
+.P
+The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
+output a representation of the compiled code after compilation. Normally this
+information contains length and offset values; however, if \fB/Z\fP is also
+present, this data is replaced by spaces. This is a special feature for use in
+the automatic test scripts; it ensures that the same output is generated for
+different internal link sizes.
+.P
+The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
+\fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
+.P
+The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
+2-byte and 4-byte fields in the compiled pattern. This facility is for testing
+the feature in PCRE that allows it to execute patterns that were compiled on a
+host with a different endianness. This feature is not available when the POSIX
+interface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
+specified. See also the section about saving and reloading compiled patterns
+below.
+.P
+The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
+compiled pattern (whether it is anchored, has a fixed first character, and
+so on). It does this by calling \fBpcre[16|32]_fullinfo()\fP after compiling a
+pattern. If the pattern is studied, the results of that are also output. In
+this output, the word "char" means a non-UTF character, that is, the value of a
+single data item (8-bit, 16-bit, or 32-bit, depending on the library that is
+being tested).
+.P
+The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
+control verbs that are returned from calls to \fBpcre[16|32]_exec()\fP. It causes
+\fBpcretest\fP to create a \fBpcre[16|32]_extra\fP block if one has not already
+been created by a call to \fBpcre[16|32]_study()\fP, and to set the
+PCRE_EXTRA_MARK flag and the \fBmark\fP field within it, every time that
+\fBpcre[16|32]_exec()\fP is called. If the variable that the \fBmark\fP field
+points to is non-NULL for a match, non-match, or partial match, \fBpcretest\fP
+prints the string to which it points. For a match, this is shown on a line by
+itself, tagged with "MK:". For a non-match it is added to the message.
+.P
+The \fB/L\fP modifier must be followed directly by the name of a locale, for
+example,
+.sp
+  /pattern/Lfr_FR
+.sp
+For this reason, it must be the last modifier. The given locale is set,
+\fBpcre[16|32]_maketables()\fP is called to build a set of character tables for
+the locale, and this is then passed to \fBpcre[16|32]_compile()\fP when compiling
+the regular expression. Without an \fB/L\fP (or \fB/T\fP) modifier, NULL is
+passed as the tables pointer; that is, \fB/L\fP applies only to the expression
+on which it appears.
+.P
+The \fB/M\fP modifier causes the size in bytes of the memory block used to hold
+the compiled pattern to be output. This does not include the size of the
+\fBpcre[16|32]\fP block; it is just the actual compiled data. If the pattern is
+successfully studied with the PCRE_STUDY_JIT_COMPILE option, the size of the
+JIT compiled code is also output.
+.P
+The \fB/Q\fP modifier is used to test the use of \fBpcre_stack_guard\fP. It
+must be followed by '0' or '1', specifying the return code to be given from an
+external function that is passed to PCRE and used for stack checking during
+compilation (see the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation for details).
+.P
+The \fB/S\fP modifier causes \fBpcre[16|32]_study()\fP to be called after the
+expression has been compiled, and the results used when the expression is
+matched. There are a number of qualifying characters that may follow \fB/S\fP.
+They may appear in any order.
+.P
+If \fB/S\fP is followed by an exclamation mark, \fBpcre[16|32]_study()\fP is
+called with the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a
+\fBpcre_extra\fP block, even when studying discovers no useful information.
+.P
+If \fB/S\fP is followed by a second S character, it suppresses studying, even
+if it was requested externally by the \fB-s\fP command line option. This makes
+it possible to specify that certain patterns are always studied, and others are
+never studied, independently of \fB-s\fP. This feature is used in the test
+files in a few cases where the output is different when the pattern is studied.
+.P
+If the \fB/S\fP modifier is followed by a + character, the call to
+\fBpcre[16|32]_study()\fP is made with all the JIT study options, requesting
+just-in-time optimization support if it is available, for both normal and
+partial matching. If you want to restrict the JIT compiling modes, you can
+follow \fB/S+\fP with a digit in the range 1 to 7:
+.sp
+  1  normal match only
+  2  soft partial match only
+  3  normal match and soft partial match
+  4  hard partial match only
+  6  soft and hard partial match
+  7  all three modes (default)
+.sp
+If \fB/S++\fP is used instead of \fB/S+\fP (with or without a following digit),
+the text "(JIT)" is added to the first output line after a match or no match
+when JIT-compiled code was actually used.
+.P
+Note that there is also an independent \fB/+\fP modifier; it must not be given
+immediately after \fB/S\fP or \fB/S+\fP because this will be misinterpreted.
+.P
+If JIT studying is successful, the compiled JIT code will automatically be used
+when \fBpcre[16|32]_exec()\fP is run, except when incompatible run-time options
+are specified. For more details, see the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation. See also the \fB\eJ\fP escape sequence below for a way of
+setting the size of the JIT stack.
+.P
+Finally, if \fB/S\fP is followed by a minus character, JIT compilation is
+suppressed, even if it was requested externally by the \fB-s\fP command line
+option. This makes it possible to specify that JIT is never to be used for
+certain patterns.
+.P
+The \fB/T\fP modifier must be followed by a single digit. It causes a specific
+set of built-in character tables to be passed to \fBpcre[16|32]_compile()\fP. It
+is used in the standard PCRE tests to check behaviour with different character
+tables. The digit specifies the tables as follows:
+.sp
+  0   the default ASCII tables, as distributed in
+        pcre_chartables.c.dist
+  1   a set of tables defining ISO 8859 characters
+.sp
+In table 1, some characters whose codes are greater than 128 are identified as
+letters, digits, spaces, etc.
+.
+.
+.SS "Using the POSIX wrapper API"
+.rs
+.sp
+The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
+API rather than its native API. This supports only the 8-bit library. When
+\fB/P\fP is set, the following modifiers set options for the \fBregcomp()\fP
+function:
+.sp
+  /i    REG_ICASE
+  /m    REG_NEWLINE
+  /N    REG_NOSUB
+  /s    REG_DOTALL     )
+  /U    REG_UNGREEDY   ) These options are not part of
+  /W    REG_UCP        )   the POSIX standard
+  /8    REG_UTF8       )
+.sp
+The \fB/+\fP modifier works as described above. All other modifiers are
+ignored.
+.
+.
+.SS "Locking out certain modifiers"
+.rs
+.sp
+PCRE can be compiled with or without support for certain features such as
+UTF-8/16/32 or Unicode properties. Accordingly, the standard tests are split up
+into a number of different files that are selected for running depending on
+which features are available. When updating the tests, it is all too easy to
+put a new test into the wrong file by mistake; for example, to put a test that
+requires UTF support into a file that is used when it is not available. To help
+detect such mistakes as early as possible, there is a facility for locking out
+specific modifiers. If an input line for \fBpcretest\fP starts with the string
+"< forbid " the following sequence of characters is taken as a list of
+forbidden modifiers. For example, in the test files that must not use UTF or
+Unicode property support, this line appears:
+.sp
+  < forbid 8W
+.sp
+This locks out the /8 and /W modifiers. An immediate error is given if they are
+subsequently encountered. If the character string contains < but not >, all the
+multi-character modifiers that begin with < are locked out. Otherwise, such
+modifiers must be explicitly listed, for example:
+.sp
+  < forbid 
+.sp
+There must be a single space between < and "forbid" for this feature to be
+recognised. If there is not, the line is interpreted either as a request to
+re-load a pre-compiled pattern (see "SAVING AND RELOADING COMPILED PATTERNS"
+below) or, if there is a another < character, as a pattern that uses < as its
+delimiter.
+.
+.
+.SH "DATA LINES"
+.rs
+.sp
+Before each data line is passed to \fBpcre[16|32]_exec()\fP, leading and trailing
+white space is removed, and it is then scanned for \e escapes. Some of these
+are pretty esoteric features, intended for checking out some of the more
+complicated features of PCRE. If you are just testing "ordinary" regular
+expressions, you probably don't need any of these. The following escapes are
+recognized:
+.sp
+  \ea         alarm (BEL, \ex07)
+  \eb         backspace (\ex08)
+  \ee         escape (\ex27)
+  \ef         form feed (\ex0c)
+  \en         newline (\ex0a)
+.\" JOIN
+  \eqdd       set the PCRE_MATCH_LIMIT limit to dd
+               (any number of digits)
+  \er         carriage return (\ex0d)
+  \et         tab (\ex09)
+  \ev         vertical tab (\ex0b)
+  \ennn       octal character (up to 3 octal digits); always
+               a byte unless > 255 in UTF-8 or 16-bit or 32-bit mode
+  \eo{dd...}  octal character (any number of octal digits}
+  \exhh       hexadecimal byte (up to 2 hex digits)
+  \ex{hh...}  hexadecimal character (any number of hex digits)
+.\" JOIN
+  \eA         pass the PCRE_ANCHORED option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \eB         pass the PCRE_NOTBOL option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \eCdd       call pcre[16|32]_copy_substring() for substring dd
+               after a successful match (number less than 32)
+.\" JOIN
+  \eCname     call pcre[16|32]_copy_named_substring() for substring
+               "name" after a successful match (name termin-
+               ated by next non alphanumeric character)
+.\" JOIN
+  \eC+        show the current captured substrings at callout
+               time
+  \eC-        do not supply a callout function
+.\" JOIN
+  \eC!n       return 1 instead of 0 when callout number n is
+               reached
+.\" JOIN
+  \eC!n!m     return 1 instead of 0 when callout number n is
+               reached for the nth time
+.\" JOIN
+  \eC*n       pass the number n (may be negative) as callout
+               data; this is used as the callout return value
+  \eD         use the \fBpcre[16|32]_dfa_exec()\fP match function
+  \eF         only shortest match for \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \eGdd       call pcre[16|32]_get_substring() for substring dd
+               after a successful match (number less than 32)
+.\" JOIN
+  \eGname     call pcre[16|32]_get_named_substring() for substring
+               "name" after a successful match (name termin-
+               ated by next non-alphanumeric character)
+.\" JOIN
+  \eJdd       set up a JIT stack of dd kilobytes maximum (any
+               number of digits)
+.\" JOIN
+  \eL         call pcre[16|32]_get_substringlist() after a
+               successful match
+.\" JOIN
+  \eM         discover the minimum MATCH_LIMIT and
+               MATCH_LIMIT_RECURSION settings
+.\" JOIN
+  \eN         pass the PCRE_NOTEMPTY option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP; if used twice, pass the
+               PCRE_NOTEMPTY_ATSTART option
+.\" JOIN
+  \eOdd       set the size of the output vector passed to
+               \fBpcre[16|32]_exec()\fP to dd (any number of digits)
+.\" JOIN
+  \eP         pass the PCRE_PARTIAL_SOFT option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP; if used twice, pass the
+               PCRE_PARTIAL_HARD option
+.\" JOIN
+  \eQdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
+               (any number of digits)
+  \eR         pass the PCRE_DFA_RESTART option to \fBpcre[16|32]_dfa_exec()\fP
+  \eS         output details of memory get/free calls during matching
+.\" JOIN
+  \eY         pass the PCRE_NO_START_OPTIMIZE option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \eZ         pass the PCRE_NOTEOL option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \e?         pass the PCRE_NO_UTF[8|16|32]_CHECK option to
+               \fBpcre[16|32]_exec()\fP or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \e>dd       start the match at offset dd (optional "-"; then
+               any number of digits); this sets the \fIstartoffset\fP
+               argument for \fBpcre[16|32]_exec()\fP or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \e      pass the PCRE_NEWLINE_CR option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \e      pass the PCRE_NEWLINE_LF option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \e    pass the PCRE_NEWLINE_CRLF option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \e pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP
+.\" JOIN
+  \e     pass the PCRE_NEWLINE_ANY option to \fBpcre[16|32]_exec()\fP
+               or \fBpcre[16|32]_dfa_exec()\fP
+.sp
+The use of \ex{hh...} is not dependent on the use of the \fB/8\fP modifier on
+the pattern. It is recognized always. There may be any number of hexadecimal
+digits inside the braces; invalid values provoke error messages.
+.P
+Note that \exhh specifies one byte rather than one character in UTF-8 mode;
+this makes it possible to construct invalid UTF-8 sequences for testing
+purposes. On the other hand, \ex{hh} is interpreted as a UTF-8 character in
+UTF-8 mode, generating more than one byte if the value is greater than 127.
+When testing the 8-bit library not in UTF-8 mode, \ex{hh} generates one byte
+for values less than 256, and causes an error for greater values.
+.P
+In UTF-16 mode, all 4-digit \ex{hhhh} values are accepted. This makes it
+possible to construct invalid UTF-16 sequences for testing purposes.
+.P
+In UTF-32 mode, all 4- to 8-digit \ex{...} values are accepted. This makes it
+possible to construct invalid UTF-32 sequences for testing purposes.
+.P
+The escapes that specify line ending sequences are literal strings, exactly as
+shown. No more than one newline setting should be present in any data line.
+.P
+A backslash followed by anything else just escapes the anything else. If
+the very last character is a backslash, it is ignored. This gives a way of
+passing an empty line as data, since a real empty line terminates the data
+input.
+.P
+The \fB\eJ\fP escape provides a way of setting the maximum stack size that is
+used by the just-in-time optimization code. It is ignored if JIT optimization
+is not being used. Providing a stack that is larger than the default 32K is
+necessary only for very complicated patterns.
+.P
+If \eM is present, \fBpcretest\fP calls \fBpcre[16|32]_exec()\fP several times,
+with different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
+fields of the \fBpcre[16|32]_extra\fP data structure, until it finds the minimum
+numbers for each parameter that allow \fBpcre[16|32]_exec()\fP to complete without
+error. Because this is testing a specific feature of the normal interpretive
+\fBpcre[16|32]_exec()\fP execution, the use of any JIT optimization that might
+have been set up by the \fB/S+\fP qualifier of \fB-s+\fP option is disabled.
+.P
+The \fImatch_limit\fP number is a measure of the amount of backtracking
+that takes place, and checking it out can be instructive. For most simple
+matches, the number is quite small, but for patterns with very large numbers of
+matching possibilities, it can become large very quickly with increasing length
+of subject string. The \fImatch_limit_recursion\fP number is a measure of how
+much stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is
+needed to complete the match attempt.
+.P
+When \eO is used, the value specified may be higher or lower than the size set
+by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
+the call of \fBpcre[16|32]_exec()\fP for the line in which it appears.
+.P
+If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
+API to be used, the only option-setting sequences that have any effect are \eB,
+\eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
+to be passed to \fBregexec()\fP.
+.
+.
+.SH "THE ALTERNATIVE MATCHING FUNCTION"
+.rs
+.sp
+By default, \fBpcretest\fP uses the standard PCRE matching function,
+\fBpcre[16|32]_exec()\fP to match each data line. PCRE also supports an
+alternative matching function, \fBpcre[16|32]_dfa_test()\fP, which operates in a
+different way, and has some restrictions. The differences between the two
+functions are described in the
+.\" HREF
+\fBpcrematching\fP
+.\"
+documentation.
+.P
+If a data line contains the \eD escape sequence, or if the command line
+contains the \fB-dfa\fP option, the alternative matching function is used.
+This function finds all possible matches at a given point. If, however, the \eF
+escape sequence is present in the data line, it stops after the first match is
+found. This is always the shortest possible match.
+.
+.
+.SH "DEFAULT OUTPUT FROM PCRETEST"
+.rs
+.sp
+This section describes the output when the normal matching function,
+\fBpcre[16|32]_exec()\fP, is being used.
+.P
+When a match succeeds, \fBpcretest\fP outputs the list of captured substrings
+that \fBpcre[16|32]_exec()\fP returns, starting with number 0 for the string that
+matched the whole pattern. Otherwise, it outputs "No match" when the return is
+PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
+substring when \fBpcre[16|32]_exec()\fP returns PCRE_ERROR_PARTIAL. (Note that
+this is the entire substring that was inspected during the partial match; it
+may include characters before the actual match start if a lookbehind assertion,
+\eK, \eb, or \eB was involved.) For any other return, \fBpcretest\fP outputs
+the PCRE negative error number and a short descriptive phrase. If the error is
+a failed UTF string check, the offset of the start of the failing character and
+the reason code are also output, provided that the size of the output vector is
+at least two. Here is an example of an interactive \fBpcretest\fP run.
+.sp
+  $ pcretest
+  PCRE version 8.13 2011-04-30
+.sp
+    re> /^abc(\ed+)/
+  data> abc123
+   0: abc123
+   1: 123
+  data> xyz
+  No match
+.sp
+Unset capturing substrings that are not followed by one that is set are not
+returned by \fBpcre[16|32]_exec()\fP, and are not shown by \fBpcretest\fP. In the
+following example, there are two capturing substrings, but when the first data
+line is matched, the second, unset substring is not shown. An "internal" unset
+substring is shown as "", as for the second data line.
+.sp
+    re> /(a)|(b)/
+  data> a
+   0: a
+   1: a
+  data> b
+   0: b
+   1: 
+   2: b
+.sp
+If the strings contain any non-printing characters, they are output as \exhh
+escapes if the value is less than 256 and UTF mode is not set. Otherwise they
+are output as \ex{hh...} escapes. See below for the definition of non-printing
+characters. If the pattern has the \fB/+\fP modifier, the output for substring
+0 is followed by the the rest of the subject string, identified by "0+" like
+this:
+.sp
+    re> /cat/+
+  data> cataract
+   0: cat
+   0+ aract
+.sp
+If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
+matching attempts are output in sequence, like this:
+.sp
+    re> /\eBi(\ew\ew)/g
+  data> Mississippi
+   0: iss
+   1: ss
+   0: iss
+   1: ss
+   0: ipp
+   1: pp
+.sp
+"No match" is output only if the first match attempt fails. Here is an example
+of a failure message (the offset 4 that is specified by \e>4 is past the end of
+the subject string):
+.sp
+    re> /xyz/
+  data> xyz\e>4
+  Error -24 (bad offset value)
+.P
+If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
+data line that is successfully matched, the substrings extracted by the
+convenience functions are output with C, G, or L after the string number
+instead of a colon. This is in addition to the normal full list. The string
+length (that is, the return from the extraction function) is given in
+parentheses after each string for \fB\eC\fP and \fB\eG\fP.
+.P
+Note that whereas patterns can be continued over several lines (a plain ">"
+prompt is used for continuations), data lines may not. However newlines can be
+included in data by means of the \en escape (or \er, \er\en, etc., depending on
+the newline sequence setting).
+.
+.
+.
+.SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
+.rs
+.sp
+When the alternative matching function, \fBpcre[16|32]_dfa_exec()\fP, is used (by
+means of the \eD escape sequence or the \fB-dfa\fP command line option), the
+output consists of a list of all the matches that start at the first point in
+the subject where there is at least one match. For example:
+.sp
+    re> /(tang|tangerine|tan)/
+  data> yellow tangerine\eD
+   0: tangerine
+   1: tang
+   2: tan
+.sp
+(Using the normal matching function on this data finds only "tang".) The
+longest matching string is always given first (and numbered zero). After a
+PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
+partially matching substring. (Note that this is the entire substring that was
+inspected during the partial match; it may include characters before the actual
+match start if a lookbehind assertion, \eK, \eb, or \eB was involved.)
+.P
+If \fB/g\fP is present on the pattern, the search for further matches resumes
+at the end of the longest match. For example:
+.sp
+    re> /(tang|tangerine|tan)/g
+  data> yellow tangerine and tangy sultana\eD
+   0: tangerine
+   1: tang
+   2: tan
+   0: tang
+   1: tan
+   0: tan
+.sp
+Since the matching function does not support substring capture, the escape
+sequences that are concerned with captured substrings are not relevant.
+.
+.
+.SH "RESTARTING AFTER A PARTIAL MATCH"
+.rs
+.sp
+When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
+indicating that the subject partially matched the pattern, you can restart the
+match with additional subject data by means of the \eR escape sequence. For
+example:
+.sp
+    re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
+  data> 23ja\eP\eD
+  Partial match: 23ja
+  data> n05\eR\eD
+   0: n05
+.sp
+For further information about partial matching, see the
+.\" HREF
+\fBpcrepartial\fP
+.\"
+documentation.
+.
+.
+.SH CALLOUTS
+.rs
+.sp
+If the pattern contains any callout requests, \fBpcretest\fP's callout function
+is called during matching. This works with both matching functions. By default,
+the called function displays the callout number, the start and current
+positions in the text at the callout time, and the next pattern item to be
+tested. For example:
+.sp
+  --->pqrabcdef
+    0    ^  ^     \ed
+.sp
+This output indicates that callout number 0 occurred for a match attempt
+starting at the fourth character of the subject string, when the pointer was at
+the seventh character of the data, and when the next pattern item was \ed. Just
+one circumflex is output if the start and current positions are the same.
+.P
+Callouts numbered 255 are assumed to be automatic callouts, inserted as a
+result of the \fB/C\fP pattern modifier. In this case, instead of showing the
+callout number, the offset in the pattern, preceded by a plus, is output. For
+example:
+.sp
+    re> /\ed?[A-E]\e*/C
+  data> E*
+  --->E*
+   +0 ^      \ed?
+   +3 ^      [A-E]
+   +8 ^^     \e*
+  +10 ^ ^
+   0: E*
+.sp
+If a pattern contains (*MARK) items, an additional line is output whenever
+a change of latest mark is passed to the callout function. For example:
+.sp
+    re> /a(*MARK:X)bc/C
+  data> abc
+  --->abc
+   +0 ^       a
+   +1 ^^      (*MARK:X)
+  +10 ^^      b
+  Latest Mark: X
+  +11 ^ ^     c
+  +12 ^  ^
+   0: abc
+.sp
+The mark changes between matching "a" and "b", but stays the same for the rest
+of the match, so nothing more is output. If, as a result of backtracking, the
+mark reverts to being unset, the text "" is output.
+.P
+The callout function in \fBpcretest\fP returns zero (carry on matching) by
+default, but you can use a \eC item in a data line (as described above) to
+change this and other parameters of the callout.
+.P
+Inserting callouts can be helpful when using \fBpcretest\fP to check
+complicated regular expressions. For further information about callouts, see
+the
+.\" HREF
+\fBpcrecallout\fP
+.\"
+documentation.
+.
+.
+.
+.SH "NON-PRINTING CHARACTERS"
+.rs
+.sp
+When \fBpcretest\fP is outputting text in the compiled version of a pattern,
+bytes other than 32-126 are always treated as non-printing characters are are
+therefore shown as hex escapes.
+.P
+When \fBpcretest\fP is outputting text that is a matched part of a subject
+string, it behaves in the same way, unless a different locale has been set for
+the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
+function to distinguish printing and non-printing characters.
+.
+.
+.
+.SH "SAVING AND RELOADING COMPILED PATTERNS"
+.rs
+.sp
+The facilities described in this section are not available when the POSIX
+interface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
+specified.
+.P
+When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
+compiled pattern to a file, by following the modifiers with > and a file name.
+For example:
+.sp
+  /pattern/im >/some/file
+.sp
+See the
+.\" HREF
+\fBpcreprecompile\fP
+.\"
+documentation for a discussion about saving and re-using compiled patterns.
+Note that if the pattern was successfully studied with JIT optimization, the
+JIT data cannot be saved.
+.P
+The data that is written is binary. The first eight bytes are the length of the
+compiled pattern data followed by the length of the optional study data, each
+written as four bytes in big-endian order (most significant byte first). If
+there is no study data (either the pattern was not studied, or studying did not
+return any data), the second length is zero. The lengths are followed by an
+exact copy of the compiled pattern. If there is additional study data, this
+(excluding any JIT data) follows immediately after the compiled pattern. After
+writing the file, \fBpcretest\fP expects to read a new pattern.
+.P
+A saved pattern can be reloaded into \fBpcretest\fP by specifying < and a file
+name instead of a pattern. There must be no space between < and the file name,
+which must not contain a < character, as otherwise \fBpcretest\fP will
+interpret the line as a pattern delimited by < characters. For example:
+.sp
+   re> " to prompt for regular expressions, and "data>" to prompt for data
+       lines.
+
+       When  pcretest  is  built,  a  configuration option can specify that it
+       should be linked with the libreadline library. When this  is  done,  if
+       the input is from a terminal, it is read using the readline() function.
+       This provides line-editing and history facilities. The output from  the
+       -help option states whether or not readline() will be used.
+
+       The program handles any number of sets of input on a single input file.
+       Each set starts with a regular expression, and continues with any  num-
+       ber of data lines to be matched against that pattern.
+
+       Each  data line is matched separately and independently. If you want to
+       do multi-line matches, you have to use the \n escape sequence (or \r or
+       \r\n, etc., depending on the newline setting) in a single line of input
+       to encode the newline sequences. There is no limit  on  the  length  of
+       data  lines;  the  input  buffer is automatically extended if it is too
+       small.
+
+       An empty line signals the end of the data lines, at which point  a  new
+       regular  expression is read. The regular expressions are given enclosed
+       in any non-alphanumeric delimiters other than backslash, for example:
+
+         /(a|bc)x+yz/
+
+       White space before the initial delimiter is ignored. A regular  expres-
+       sion  may be continued over several input lines, in which case the new-
+       line characters are included within it. It is possible to  include  the
+       delimiter within the pattern by escaping it, for example
+
+         /abc\/def/
+
+       If  you  do  so, the escape and the delimiter form part of the pattern,
+       but since delimiters are always non-alphanumeric, this does not  affect
+       its  interpretation.   If the terminating delimiter is immediately fol-
+       lowed by a backslash, for example,
+
+         /abc/\
+
+       then a backslash is added to the end of the pattern. This  is  done  to
+       provide  a  way of testing the error condition that arises if a pattern
+       finishes with a backslash, because
+
+         /abc\/
+
+       is interpreted as the first line of a pattern that starts with  "abc/",
+       causing pcretest to read the next line as a continuation of the regular
+       expression.
+
+
+PATTERN MODIFIERS
+
+       A pattern may be followed by any number of modifiers, which are  mostly
+       single  characters,  though  some  of these can be qualified by further
+       characters.  Following Perl usage, these are referred to below as,  for
+       example,  "the  /i  modifier", even though the delimiter of the pattern
+       need not always be a slash, and no slash is  used  when  writing  modi-
+       fiers.  White  space may appear between the final pattern delimiter and
+       the first modifier, and between the modifiers  themselves.  For  refer-
+       ence,  here  is  a  complete  list of modifiers. They fall into several
+       groups that are described in detail in the following sections.
+
+         /8              set UTF mode
+         /9              set PCRE_NEVER_UTF (locks out UTF mode)
+         /?              disable UTF validity check
+         /+              show remainder of subject after match
+         /=              show all captures (not just those that are set)
+
+         /A              set PCRE_ANCHORED
+         /B              show compiled code
+         /C              set PCRE_AUTO_CALLOUT
+         /D              same as /B plus /I
+         /E              set PCRE_DOLLAR_ENDONLY
+         /F              flip byte order in compiled pattern
+         /f              set PCRE_FIRSTLINE
+         /G              find all matches (shorten string)
+         /g              find all matches (use startoffset)
+         /I              show information about pattern
+         /i              set PCRE_CASELESS
+         /J              set PCRE_DUPNAMES
+         /K              show backtracking control names
+         /L              set locale
+         /M              show compiled memory size
+         /m              set PCRE_MULTILINE
+         /N              set PCRE_NO_AUTO_CAPTURE
+         /O              set PCRE_NO_AUTO_POSSESS
+         /P              use the POSIX wrapper
+         /Q              test external stack check function
+         /S              study the pattern after compilation
+         /s              set PCRE_DOTALL
+         /T              select character tables
+         /U              set PCRE_UNGREEDY
+         /W              set PCRE_UCP
+         /X              set PCRE_EXTRA
+         /x              set PCRE_EXTENDED
+         /Y              set PCRE_NO_START_OPTIMIZE
+         /Z              don't show lengths in /B output
+
+         /          set PCRE_NEWLINE_ANY
+         /      set PCRE_NEWLINE_ANYCRLF
+         /           set PCRE_NEWLINE_CR
+         /         set PCRE_NEWLINE_CRLF
+         /           set PCRE_NEWLINE_LF
+         /  set PCRE_BSR_ANYCRLF
+         /  set PCRE_BSR_UNICODE
+         /           set PCRE_JAVASCRIPT_COMPAT
+
+
+   Perl-compatible modifiers
+
+       The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
+       PCRE_DOTALL,    or    PCRE_EXTENDED    options,    respectively,   when
+       pcre[16|32]_compile() is called. These four modifier letters  have  the
+       same effect as they do in Perl. For example:
+
+         /caseless/i
+
+
+   Modifiers for other PCRE options
+
+       The  following  table  shows additional modifiers for setting PCRE com-
+       pile-time options that do not correspond to anything in Perl:
+
+         /8              PCRE_UTF8           ) when using the 8-bit
+         /?              PCRE_NO_UTF8_CHECK  )   library
+
+         /8              PCRE_UTF16          ) when using the 16-bit
+         /?              PCRE_NO_UTF16_CHECK )   library
+
+         /8              PCRE_UTF32          ) when using the 32-bit
+         /?              PCRE_NO_UTF32_CHECK )   library
+
+         /9              PCRE_NEVER_UTF
+         /A              PCRE_ANCHORED
+         /C              PCRE_AUTO_CALLOUT
+         /E              PCRE_DOLLAR_ENDONLY
+         /f              PCRE_FIRSTLINE
+         /J              PCRE_DUPNAMES
+         /N              PCRE_NO_AUTO_CAPTURE
+         /O              PCRE_NO_AUTO_POSSESS
+         /U              PCRE_UNGREEDY
+         /W              PCRE_UCP
+         /X              PCRE_EXTRA
+         /Y              PCRE_NO_START_OPTIMIZE
+         /          PCRE_NEWLINE_ANY
+         /      PCRE_NEWLINE_ANYCRLF
+         /           PCRE_NEWLINE_CR
+         /         PCRE_NEWLINE_CRLF
+         /           PCRE_NEWLINE_LF
+         /  PCRE_BSR_ANYCRLF
+         /  PCRE_BSR_UNICODE
+         /           PCRE_JAVASCRIPT_COMPAT
+
+       The modifiers that are enclosed in angle brackets are  literal  strings
+       as  shown,  including the angle brackets, but the letters within can be
+       in either case.  This example sets multiline matching with CRLF as  the
+       line ending sequence:
+
+         /^abc/m
+
+       As  well  as  turning  on  the  PCRE_UTF8/16/32 option, the /8 modifier
+       causes all non-printing characters in  output  strings  to  be  printed
+       using the \x{hh...} notation. Otherwise, those less than 0x100 are out-
+       put in hex without the curly brackets.
+
+       Full details of the PCRE options are given in  the  pcreapi  documenta-
+       tion.
+
+   Finding all matches in a string
+
+       Searching  for  all  possible matches within each subject string can be
+       requested by the /g or /G modifier. After  finding  a  match,  PCRE  is
+       called again to search the remainder of the subject string. The differ-
+       ence between /g and /G is that the former uses the startoffset argument
+       to  pcre[16|32]_exec()  to  start  searching  at a new point within the
+       entire string (which is in effect what Perl does), whereas  the  latter
+       passes  over  a  shortened  substring.  This  makes a difference to the
+       matching process if the pattern  begins  with  a  lookbehind  assertion
+       (including \b or \B).
+
+       If  any  call  to  pcre[16|32]_exec() in a /g or /G sequence matches an
+       empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART  and
+       PCRE_ANCHORED  flags  set  in  order  to search for another, non-empty,
+       match at the same point. If this second match fails, the  start  offset
+       is  advanced,  and  the  normal match is retried. This imitates the way
+       Perl handles such cases when using the /g modifier or the split() func-
+       tion.  Normally,  the start offset is advanced by one character, but if
+       the newline convention recognizes CRLF as a newline,  and  the  current
+       character is CR followed by LF, an advance of two is used.
+
+   Other modifiers
+
+       There are yet more modifiers for controlling the way pcretest operates.
+
+       The  /+ modifier requests that as well as outputting the substring that
+       matched the entire pattern, pcretest  should  in  addition  output  the
+       remainder  of  the  subject  string. This is useful for tests where the
+       subject contains multiple copies of the same substring. If the +  modi-
+       fier  appears  twice, the same action is taken for captured substrings.
+       In each case the remainder is output on the following line with a  plus
+       character  following  the  capture number. Note that this modifier must
+       not immediately follow the /S modifier because /S+ and /S++ have  other
+       meanings.
+
+       The  /=  modifier  requests  that  the values of all potential captured
+       parentheses be output after a match. By default, only those up  to  the
+       highest one actually used in the match are output (corresponding to the
+       return code from pcre[16|32]_exec()). Values in the offsets vector cor-
+       responding  to higher numbers should be set to -1, and these are output
+       as "". This modifier gives a way of checking that this  is  hap-
+       pening.
+
+       The  /B modifier is a debugging feature. It requests that pcretest out-
+       put a representation of the compiled code after  compilation.  Normally
+       this  information  contains length and offset values; however, if /Z is
+       also present, this data is replaced by spaces. This is a  special  fea-
+       ture  for  use  in the automatic test scripts; it ensures that the same
+       output is generated for different internal link sizes.
+
+       The /D modifier is a PCRE debugging feature, and is equivalent to  /BI,
+       that is, both the /B and the /I modifiers.
+
+       The  /F  modifier  causes pcretest to flip the byte order of the 2-byte
+       and 4-byte fields in the compiled pattern. This facility is for testing
+       the  feature  in PCRE that allows it to execute patterns that were com-
+       piled on a host with a different endianness. This feature is not avail-
+       able  when the POSIX interface to PCRE is being used, that is, when the
+       /P pattern modifier is specified. See also the section about saving and
+       reloading compiled patterns below.
+
+       The  /I  modifier  requests  that pcretest output information about the
+       compiled pattern (whether it is anchored, has a fixed first  character,
+       and  so  on). It does this by calling pcre[16|32]_fullinfo() after com-
+       piling a pattern. If the pattern is studied, the results  of  that  are
+       also output. In this output, the word "char" means a non-UTF character,
+       that is, the value of a single data item  (8-bit,  16-bit,  or  32-bit,
+       depending on the library that is being tested).
+
+       The  /K modifier requests pcretest to show names from backtracking con-
+       trol verbs that are  returned  from  calls  to  pcre[16|32]_exec().  It
+       causes  pcretest  to  create  a  pcre[16|32]_extra block if one has not
+       already been created by a call to pcre[16|32]_study(), and to  set  the
+       PCRE_EXTRA_MARK  flag  and  the  mark  field within it, every time that
+       pcre[16|32]_exec() is called. If  the  variable  that  the  mark  field
+       points  to  is  non-NULL  for  a  match,  non-match,  or partial match,
+       pcretest prints the string to which it points. For  a  match,  this  is
+       shown  on  a  line  by itself, tagged with "MK:". For a non-match it is
+       added to the message.
+
+       The /L modifier must be followed directly by the name of a locale,  for
+       example,
+
+         /pattern/Lfr_FR
+
+       For this reason, it must be the last modifier. The given locale is set,
+       pcre[16|32]_maketables() is called to build a set of  character  tables
+       for  the  locale, and this is then passed to pcre[16|32]_compile() when
+       compiling the regular expression. Without an /L (or /T) modifier,  NULL
+       is  passed  as  the  tables  pointer;  that  is, /L applies only to the
+       expression on which it appears.
+
+       The /M modifier causes the size in bytes of the memory  block  used  to
+       hold  the compiled pattern to be output. This does not include the size
+       of the pcre[16|32] block; it is just the actual compiled data.  If  the
+       pattern is successfully studied with the PCRE_STUDY_JIT_COMPILE option,
+       the size of the JIT compiled code is also output.
+
+       The /Q modifier is used to test the use of pcre_stack_guard. It must be
+       followed  by '0' or '1', specifying the return code to be given from an
+       external function that is passed to PCRE and used  for  stack  checking
+       during compilation (see the pcreapi documentation for details).
+
+       The  /S  modifier  causes  pcre[16|32]_study()  to  be called after the
+       expression has been compiled, and the results used when the  expression
+       is matched. There are a number of qualifying characters that may follow
+       /S.  They may appear in any order.
+
+       If /S is followed by an exclamation mark, pcre[16|32]_study() is called
+       with  the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a
+       pcre_extra block, even when studying discovers no useful information.
+
+       If /S is followed by a second S character, it suppresses studying, even
+       if  it  was  requested  externally  by the -s command line option. This
+       makes it possible to specify that certain patterns are always  studied,
+       and others are never studied, independently of -s. This feature is used
+       in the test files in a few cases where the output is different when the
+       pattern is studied.
+
+       If  the  /S  modifier  is  followed  by  a  +  character,  the  call to
+       pcre[16|32]_study() is made with all the JIT study options,  requesting
+       just-in-time  optimization  support if it is available, for both normal
+       and partial matching. If you want to restrict the JIT compiling  modes,
+       you can follow /S+ with a digit in the range 1 to 7:
+
+         1  normal match only
+         2  soft partial match only
+         3  normal match and soft partial match
+         4  hard partial match only
+         6  soft and hard partial match
+         7  all three modes (default)
+
+       If /S++ is used instead of /S+ (with or without a following digit), the
+       text "(JIT)" is added to the first output line  after  a  match  or  no
+       match when JIT-compiled code was actually used.
+
+       Note  that  there  is  also  an independent /+ modifier; it must not be
+       given immediately after /S or /S+ because this will be misinterpreted.
+
+       If JIT studying is successful, the compiled JIT code will automatically
+       be  used  when pcre[16|32]_exec() is run, except when incompatible run-
+       time options are specified. For more details, see the pcrejit  documen-
+       tation.  See also the \J escape sequence below for a way of setting the
+       size of the JIT stack.
+
+       Finally, if /S is followed by a minus  character,  JIT  compilation  is
+       suppressed,  even if it was requested externally by the -s command line
+       option. This makes it possible to specify that JIT is never to be  used
+       for certain patterns.
+
+       The  /T  modifier  must be followed by a single digit. It causes a spe-
+       cific set of built-in character tables to be passed to pcre[16|32]_com-
+       pile().  It  is used in the standard PCRE tests to check behaviour with
+       different character tables. The digit specifies the tables as follows:
+
+         0   the default ASCII tables, as distributed in
+               pcre_chartables.c.dist
+         1   a set of tables defining ISO 8859 characters
+
+       In table 1, some characters whose codes are greater than 128 are  iden-
+       tified as letters, digits, spaces, etc.
+
+   Using the POSIX wrapper API
+
+       The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
+       rather than its native API. This supports only the 8-bit library.  When
+       /P  is set, the following modifiers set options for the regcomp() func-
+       tion:
+
+         /i    REG_ICASE
+         /m    REG_NEWLINE
+         /N    REG_NOSUB
+         /s    REG_DOTALL     )
+         /U    REG_UNGREEDY   ) These options are not part of
+         /W    REG_UCP        )   the POSIX standard
+         /8    REG_UTF8       )
+
+       The /+ modifier works as  described  above.  All  other  modifiers  are
+       ignored.
+
+   Locking out certain modifiers
+
+       PCRE  can be compiled with or without support for certain features such
+       as UTF-8/16/32 or Unicode properties. Accordingly, the  standard  tests
+       are  split  up  into  a number of different files that are selected for
+       running depending on which features are available.  When  updating  the
+       tests, it is all too easy to put a new test into the wrong file by mis-
+       take; for example, to put a test that requires UTF support into a  file
+       that  is used when it is not available. To help detect such mistakes as
+       early as possible, there is a facility for locking out  specific  modi-
+       fiers. If an input line for pcretest starts with the string "< forbid "
+       the following sequence of characters is taken as a  list  of  forbidden
+       modifiers. For example, in the test files that must not use UTF or Uni-
+       code property support, this line appears:
+
+         < forbid 8W
+
+       This locks out the /8 and /W modifiers. An immediate error is given  if
+       they  are  subsequently encountered. If the character string contains <
+       but not >, all the multi-character modifiers  that  begin  with  <  are
+       locked  out.  Otherwise,  such modifiers must be explicitly listed, for
+       example:
+
+         < forbid 
+
+       There must be a single space between < and "forbid" for this feature to
+       be  recognised.  If  there  is not, the line is interpreted either as a
+       request to re-load a pre-compiled pattern (see  "SAVING  AND  RELOADING
+       COMPILED  PATTERNS"  below) or, if there is a another < character, as a
+       pattern that uses < as its delimiter.
+
+
+DATA LINES
+
+       Before each data line is  passed  to  pcre[16|32]_exec(),  leading  and
+       trailing  white space is removed, and it is then scanned for \ escapes.
+       Some of these are pretty esoteric features, intended for  checking  out
+       some  of the more complicated features of PCRE. If you are just testing
+       "ordinary" regular expressions, you probably don't need any  of  these.
+       The following escapes are recognized:
+
+         \a         alarm (BEL, \x07)
+         \b         backspace (\x08)
+         \e         escape (\x27)
+         \f         form feed (\x0c)
+         \n         newline (\x0a)
+         \qdd       set the PCRE_MATCH_LIMIT limit to dd
+                      (any number of digits)
+         \r         carriage return (\x0d)
+         \t         tab (\x09)
+         \v         vertical tab (\x0b)
+         \nnn       octal character (up to 3 octal digits); always
+                      a byte unless > 255 in UTF-8 or 16-bit or 32-bit mode
+         \o{dd...}  octal character (any number of octal digits}
+         \xhh       hexadecimal byte (up to 2 hex digits)
+         \x{hh...}  hexadecimal character (any number of hex digits)
+         \A         pass the PCRE_ANCHORED option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec()
+         \B         pass the PCRE_NOTBOL option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec()
+         \Cdd       call pcre[16|32]_copy_substring() for substring dd
+                      after a successful match (number less than 32)
+         \Cname     call pcre[16|32]_copy_named_substring() for substring
+                      "name" after a successful match (name termin-
+                      ated by next non alphanumeric character)
+         \C+        show the current captured substrings at callout
+                      time
+         \C-        do not supply a callout function
+         \C!n       return 1 instead of 0 when callout number n is
+                      reached
+         \C!n!m     return 1 instead of 0 when callout number n is
+                      reached for the nth time
+         \C*n       pass the number n (may be negative) as callout
+                      data; this is used as the callout return value
+         \D         use the pcre[16|32]_dfa_exec() match function
+         \F         only shortest match for pcre[16|32]_dfa_exec()
+         \Gdd       call pcre[16|32]_get_substring() for substring dd
+                      after a successful match (number less than 32)
+         \Gname     call pcre[16|32]_get_named_substring() for substring
+                      "name" after a successful match (name termin-
+                      ated by next non-alphanumeric character)
+         \Jdd       set up a JIT stack of dd kilobytes maximum (any
+                      number of digits)
+         \L         call pcre[16|32]_get_substringlist() after a
+                      successful match
+         \M         discover the minimum MATCH_LIMIT and
+                      MATCH_LIMIT_RECURSION settings
+         \N         pass the PCRE_NOTEMPTY option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec(); if used twice, pass the
+                      PCRE_NOTEMPTY_ATSTART option
+         \Odd       set the size of the output vector passed to
+                      pcre[16|32]_exec() to dd (any number of digits)
+         \P         pass the PCRE_PARTIAL_SOFT option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec(); if used twice, pass the
+                      PCRE_PARTIAL_HARD option
+         \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
+                      (any number of digits)
+         \R         pass the PCRE_DFA_RESTART option to pcre[16|32]_dfa_exec()
+         \S         output details of memory get/free calls during matching
+         \Y             pass     the    PCRE_NO_START_OPTIMIZE    option    to
+       pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec()
+         \Z         pass the PCRE_NOTEOL option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec()
+         \?         pass the PCRE_NO_UTF[8|16|32]_CHECK option to
+                      pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
+         \>dd       start the match at offset dd (optional "-"; then
+                      any number of digits); this sets the startoffset
+                      argument        for        pcre[16|32]_exec()         or
+       pcre[16|32]_dfa_exec()
+         \      pass the PCRE_NEWLINE_CR option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec()
+         \      pass the PCRE_NEWLINE_LF option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec()
+         \    pass the PCRE_NEWLINE_CRLF option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec()
+         \ pass the PCRE_NEWLINE_ANYCRLF option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec()
+         \     pass the PCRE_NEWLINE_ANY option to pcre[16|32]_exec()
+                      or pcre[16|32]_dfa_exec()
+
+       The  use of \x{hh...} is not dependent on the use of the /8 modifier on
+       the pattern. It is recognized always. There may be any number of  hexa-
+       decimal  digits  inside  the  braces; invalid values provoke error mes-
+       sages.
+
+       Note that \xhh specifies one byte rather than one  character  in  UTF-8
+       mode;  this  makes it possible to construct invalid UTF-8 sequences for
+       testing purposes. On the other hand, \x{hh} is interpreted as  a  UTF-8
+       character  in UTF-8 mode, generating more than one byte if the value is
+       greater than 127.  When testing the 8-bit library not  in  UTF-8  mode,
+       \x{hh} generates one byte for values less than 256, and causes an error
+       for greater values.
+
+       In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
+       possible to construct invalid UTF-16 sequences for testing purposes.
+
+       In  UTF-32  mode,  all  4- to 8-digit \x{...} values are accepted. This
+       makes it possible to construct invalid  UTF-32  sequences  for  testing
+       purposes.
+
+       The  escapes  that  specify  line ending sequences are literal strings,
+       exactly as shown. No more than one newline setting should be present in
+       any data line.
+
+       A  backslash  followed by anything else just escapes the anything else.
+       If the very last character is a backslash, it is ignored. This gives  a
+       way  of  passing  an empty line as data, since a real empty line termi-
+       nates the data input.
+
+       The \J escape provides a way of setting the maximum stack size that  is
+       used  by the just-in-time optimization code. It is ignored if JIT opti-
+       mization is not being used. Providing a stack that is larger  than  the
+       default 32K is necessary only for very complicated patterns.
+
+       If \M is present, pcretest calls pcre[16|32]_exec() several times, with
+       different values in the match_limit and match_limit_recursion fields of
+       the  pcre[16|32]_extra  data structure, until it finds the minimum num-
+       bers for each parameter that allow pcre[16|32]_exec() to complete with-
+       out  error.  Because  this  is testing a specific feature of the normal
+       interpretive pcre[16|32]_exec() execution, the use of any JIT optimiza-
+       tion  that might have been set up by the /S+ qualifier of -s+ option is
+       disabled.
+
+       The match_limit number is a measure of the amount of backtracking  that
+       takes  place,  and  checking it out can be instructive. For most simple
+       matches, the number is quite small, but for patterns  with  very  large
+       numbers  of  matching  possibilities,  it can become large very quickly
+       with increasing length of  subject  string.  The  match_limit_recursion
+       number  is  a  measure  of how much stack (or, if PCRE is compiled with
+       NO_RECURSE, how much heap) memory  is  needed  to  complete  the  match
+       attempt.
+
+       When  \O  is  used, the value specified may be higher or lower than the
+       size set by the -O command line option (or defaulted to 45); \O applies
+       only  to  the  call  of  pcre[16|32]_exec()  for  the  line in which it
+       appears.
+
+       If the /P modifier was present on the pattern, causing the POSIX  wrap-
+       per  API  to  be  used, the only option-setting sequences that have any
+       effect are \B,  \N,  and  \Z,  causing  REG_NOTBOL,  REG_NOTEMPTY,  and
+       REG_NOTEOL, respectively, to be passed to regexec().
+
+
+THE ALTERNATIVE MATCHING FUNCTION
+
+       By   default,  pcretest  uses  the  standard  PCRE  matching  function,
+       pcre[16|32]_exec() to match each  data  line.  PCRE  also  supports  an
+       alternative  matching  function, pcre[16|32]_dfa_test(), which operates
+       in a different way, and has some restrictions. The differences  between
+       the two functions are described in the pcrematching documentation.
+
+       If  a data line contains the \D escape sequence, or if the command line
+       contains the -dfa option, the alternative matching  function  is  used.
+       This function finds all possible matches at a given point. If, however,
+       the \F escape sequence is present in the data line, it stops after  the
+       first match is found. This is always the shortest possible match.
+
+
+DEFAULT OUTPUT FROM PCRETEST
+
+       This  section  describes  the output when the normal matching function,
+       pcre[16|32]_exec(), is being used.
+
+       When a match succeeds, pcretest outputs the list of captured substrings
+       that  pcre[16|32]_exec() returns, starting with number 0 for the string
+       that matched the whole pattern. Otherwise, it outputs "No  match"  when
+       the  return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the
+       partially   matching   substring   when   pcre[16|32]_exec()    returns
+       PCRE_ERROR_PARTIAL.  (Note  that  this is the entire substring that was
+       inspected during the partial match; it may  include  characters  before
+       the  actual  match  start  if a lookbehind assertion, \K, \b, or \B was
+       involved.) For any other return, pcretest  outputs  the  PCRE  negative
+       error  number  and a short descriptive phrase. If the error is a failed
+       UTF string check, the offset of the start of the failing character  and
+       the  reason  code are also output, provided that the size of the output
+       vector is at least two. Here is an example of an  interactive  pcretest
+       run.
+
+         $ pcretest
+         PCRE version 8.13 2011-04-30
+
+           re> /^abc(\d+)/
+         data> abc123
+          0: abc123
+          1: 123
+         data> xyz
+         No match
+
+       Unset capturing substrings that are not followed by one that is set are
+       not returned by pcre[16|32]_exec(), and are not shown by  pcretest.  In
+       the following example, there are two capturing substrings, but when the
+       first data line is matched, the second, unset substring is  not  shown.
+       An  "internal" unset substring is shown as "", as for the second
+       data line.
+
+           re> /(a)|(b)/
+         data> a
+          0: a
+          1: a
+         data> b
+          0: b
+          1: 
+          2: b
+
+       If the strings contain any non-printing characters, they are output  as
+       \xhh  escapes  if  the  value is less than 256 and UTF mode is not set.
+       Otherwise they are output as \x{hh...} escapes. See below for the defi-
+       nition  of non-printing characters. If the pattern has the /+ modifier,
+       the output for substring 0 is followed by the the rest of  the  subject
+       string, identified by "0+" like this:
+
+           re> /cat/+
+         data> cataract
+          0: cat
+          0+ aract
+
+       If  the  pattern  has  the /g or /G modifier, the results of successive
+       matching attempts are output in sequence, like this:
+
+           re> /\Bi(\w\w)/g
+         data> Mississippi
+          0: iss
+          1: ss
+          0: iss
+          1: ss
+          0: ipp
+          1: pp
+
+       "No match" is output only if the first match attempt fails. Here is  an
+       example  of a failure message (the offset 4 that is specified by \>4 is
+       past the end of the subject string):
+
+           re> /xyz/
+         data> xyz\>4
+         Error -24 (bad offset value)
+
+       If any of the sequences \C, \G, or \L are present in a data  line  that
+       is  successfully  matched,  the substrings extracted by the convenience
+       functions are output with C, G, or L after the string number instead of
+       a colon. This is in addition to the normal full list. The string length
+       (that is, the return from the extraction function) is given  in  paren-
+       theses after each string for \C and \G.
+
+       Note that whereas patterns can be continued over several lines (a plain
+       ">" prompt is used for continuations), data lines may not. However new-
+       lines  can  be included in data by means of the \n escape (or \r, \r\n,
+       etc., depending on the newline sequence setting).
+
+
+OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
+
+       When the alternative matching function, pcre[16|32]_dfa_exec(), is used
+       (by  means  of the \D escape sequence or the -dfa command line option),
+       the output consists of a list of all the  matches  that  start  at  the
+       first point in the subject where there is at least one match. For exam-
+       ple:
+
+           re> /(tang|tangerine|tan)/
+         data> yellow tangerine\D
+          0: tangerine
+          1: tang
+          2: tan
+
+       (Using the normal matching function on this data  finds  only  "tang".)
+       The  longest matching string is always given first (and numbered zero).
+       After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
+       lowed  by  the  partially  matching  substring.  (Note that this is the
+       entire substring that was inspected during the partial  match;  it  may
+       include characters before the actual match start if a lookbehind asser-
+       tion, \K, \b, or \B was involved.)
+
+       If /g is present on the pattern, the search for further matches resumes
+       at the end of the longest match. For example:
+
+           re> /(tang|tangerine|tan)/g
+         data> yellow tangerine and tangy sultana\D
+          0: tangerine
+          1: tang
+          2: tan
+          0: tang
+          1: tan
+          0: tan
+
+       Since  the  matching  function  does not support substring capture, the
+       escape sequences that are concerned with captured  substrings  are  not
+       relevant.
+
+
+RESTARTING AFTER A PARTIAL MATCH
+
+       When the alternative matching function has given the PCRE_ERROR_PARTIAL
+       return, indicating that the subject partially matched the pattern,  you
+       can  restart  the match with additional subject data by means of the \R
+       escape sequence. For example:
+
+           re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
+         data> 23ja\P\D
+         Partial match: 23ja
+         data> n05\R\D
+          0: n05
+
+       For further information about partial  matching,  see  the  pcrepartial
+       documentation.
+
+
+CALLOUTS
+
+       If  the pattern contains any callout requests, pcretest's callout func-
+       tion is called during matching. This works  with  both  matching  func-
+       tions. By default, the called function displays the callout number, the
+       start and current positions in the text at the callout  time,  and  the
+       next pattern item to be tested. For example:
+
+         --->pqrabcdef
+           0    ^  ^     \d
+
+       This  output  indicates  that  callout  number  0  occurred for a match
+       attempt starting at the fourth character of the  subject  string,  when
+       the pointer was at the seventh character of the data, and when the next
+       pattern item was \d. Just one circumflex is output  if  the  start  and
+       current positions are the same.
+
+       Callouts numbered 255 are assumed to be automatic callouts, inserted as
+       a result of the /C pattern modifier. In this case, instead  of  showing
+       the  callout  number, the offset in the pattern, preceded by a plus, is
+       output. For example:
+
+           re> /\d?[A-E]\*/C
+         data> E*
+         --->E*
+          +0 ^      \d?
+          +3 ^      [A-E]
+          +8 ^^     \*
+         +10 ^ ^
+          0: E*
+
+       If a pattern contains (*MARK) items, an additional line is output when-
+       ever  a  change  of  latest mark is passed to the callout function. For
+       example:
+
+           re> /a(*MARK:X)bc/C
+         data> abc
+         --->abc
+          +0 ^       a
+          +1 ^^      (*MARK:X)
+         +10 ^^      b
+         Latest Mark: X
+         +11 ^ ^     c
+         +12 ^  ^
+          0: abc
+
+       The mark changes between matching "a" and "b", but stays the  same  for
+       the  rest  of  the match, so nothing more is output. If, as a result of
+       backtracking, the mark reverts to being unset, the  text  ""  is
+       output.
+
+       The  callout  function  in pcretest returns zero (carry on matching) by
+       default, but you can use a \C item in a data line (as described  above)
+       to change this and other parameters of the callout.
+
+       Inserting  callouts can be helpful when using pcretest to check compli-
+       cated regular expressions. For further information about callouts,  see
+       the pcrecallout documentation.
+
+
+NON-PRINTING CHARACTERS
+
+       When  pcretest is outputting text in the compiled version of a pattern,
+       bytes other than 32-126 are always treated as  non-printing  characters
+       are are therefore shown as hex escapes.
+
+       When  pcretest  is  outputting text that is a matched part of a subject
+       string, it behaves in the same way, unless a different locale has  been
+       set  for  the  pattern  (using  the  /L  modifier).  In  this case, the
+       isprint() function to distinguish printing and non-printing characters.
+
+
+SAVING AND RELOADING COMPILED PATTERNS
+
+       The facilities described in this section are  not  available  when  the
+       POSIX  interface  to  PCRE  is being used, that is, when the /P pattern
+       modifier is specified.
+
+       When the POSIX interface is not in use, you can cause pcretest to write
+       a  compiled  pattern to a file, by following the modifiers with > and a
+       file name.  For example:
+
+         /pattern/im >/some/file
+
+       See the pcreprecompile documentation for a discussion about saving  and
+       re-using  compiled patterns.  Note that if the pattern was successfully
+       studied with JIT optimization, the JIT data cannot be saved.
+
+       The data that is written is binary.  The  first  eight  bytes  are  the
+       length  of  the  compiled  pattern  data  followed by the length of the
+       optional study data, each written as four  bytes  in  big-endian  order
+       (most  significant  byte  first). If there is no study data (either the
+       pattern was not studied, or studying did not return any data), the sec-
+       ond  length  is  zero. The lengths are followed by an exact copy of the
+       compiled pattern. If there is additional study  data,  this  (excluding
+       any  JIT  data)  follows  immediately after the compiled pattern. After
+       writing the file, pcretest expects to read a new pattern.
+
+       A saved pattern can be reloaded into pcretest by  specifying  <  and  a
+       file  name  instead  of a pattern. There must be no space between < and
+       the file name, which must not  contain  a  <  character,  as  otherwise
+       pcretest  will  interpret  the line as a pattern delimited by < charac-
+       ters. For example:
+
+          re> 
+.SS "Validity of UTF-8 strings"
+.rs
+.sp
+When you set the PCRE_UTF8 flag, the byte strings passed as patterns and
+subjects are (by default) checked for validity on entry to the relevant
+functions. The entire string is checked before any other processing takes
+place. From release 7.3 of PCRE, the check is according the rules of RFC 3629,
+which are themselves derived from the Unicode specification. Earlier releases
+of PCRE followed the rules of RFC 2279, which allows the full range of 31-bit
+values (0 to 0x7FFFFFFF). The current check allows only values in the range U+0
+to U+10FFFF, excluding the surrogate area. (From release 8.33 the so-called
+"non-character" code points are no longer excluded because Unicode corrigendum
+#9 makes it clear that they should not be.)
+.P
+Characters in the "Surrogate Area" of Unicode are reserved for use by UTF-16,
+where they are used in pairs to encode codepoints with values greater than
+0xFFFF. The code points that are encoded by UTF-16 pairs are available
+independently in the UTF-8 and UTF-32 encodings. (In other words, the whole
+surrogate thing is a fudge for UTF-16 which unfortunately messes up UTF-8 and
+UTF-32.)
+.P
+If an invalid UTF-8 string is passed to PCRE, an error return is given. At
+compile time, the only additional information is the offset to the first byte
+of the failing character. The run-time functions \fBpcre_exec()\fP and
+\fBpcre_dfa_exec()\fP also pass back this information, as well as a more
+detailed reason code if the caller has provided memory in which to do this.
+.P
+In some situations, you may already know that your strings are valid, and
+therefore want to skip these checks in order to improve performance, for
+example in the case of a long subject string that is being scanned repeatedly.
+If you set the PCRE_NO_UTF8_CHECK flag at compile time or at run time, PCRE
+assumes that the pattern or subject it is given (respectively) contains only
+valid UTF-8 codes. In this case, it does not diagnose an invalid UTF-8 string.
+.P
+Note that passing PCRE_NO_UTF8_CHECK to \fBpcre_compile()\fP just disables the
+check for the pattern; it does not also apply to subject strings. If you want
+to disable the check for a subject string you must pass this option to
+\fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP.
+.P
+If you pass an invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set, the result
+is undefined and your program may crash.
+.
+.
+.\" HTML 
+.SS "Validity of UTF-16 strings"
+.rs
+.sp
+When you set the PCRE_UTF16 flag, the strings of 16-bit data units that are
+passed as patterns and subjects are (by default) checked for validity on entry
+to the relevant functions. Values other than those in the surrogate range
+U+D800 to U+DFFF are independent code points. Values in the surrogate range
+must be used in pairs in the correct manner.
+.P
+If an invalid UTF-16 string is passed to PCRE, an error return is given. At
+compile time, the only additional information is the offset to the first data
+unit of the failing character. The run-time functions \fBpcre16_exec()\fP and
+\fBpcre16_dfa_exec()\fP also pass back this information, as well as a more
+detailed reason code if the caller has provided memory in which to do this.
+.P
+In some situations, you may already know that your strings are valid, and
+therefore want to skip these checks in order to improve performance. If you set
+the PCRE_NO_UTF16_CHECK flag at compile time or at run time, PCRE assumes that
+the pattern or subject it is given (respectively) contains only valid UTF-16
+sequences. In this case, it does not diagnose an invalid UTF-16 string.
+However, if an invalid string is passed, the result is undefined.
+.
+.
+.\" HTML 
+.SS "Validity of UTF-32 strings"
+.rs
+.sp
+When you set the PCRE_UTF32 flag, the strings of 32-bit data units that are
+passed as patterns and subjects are (by default) checked for validity on entry
+to the relevant functions.  This check allows only values in the range U+0
+to U+10FFFF, excluding the surrogate area U+D800 to U+DFFF.
+.P
+If an invalid UTF-32 string is passed to PCRE, an error return is given. At
+compile time, the only additional information is the offset to the first data
+unit of the failing character. The run-time functions \fBpcre32_exec()\fP and
+\fBpcre32_dfa_exec()\fP also pass back this information, as well as a more
+detailed reason code if the caller has provided memory in which to do this.
+.P
+In some situations, you may already know that your strings are valid, and
+therefore want to skip these checks in order to improve performance. If you set
+the PCRE_NO_UTF32_CHECK flag at compile time or at run time, PCRE assumes that
+the pattern or subject it is given (respectively) contains only valid UTF-32
+sequences. In this case, it does not diagnose an invalid UTF-32 string.
+However, if an invalid string is passed, the result is undefined.
+.
+.
+.SS "General comments about UTF modes"
+.rs
+.sp
+1. Codepoints less than 256 can be specified in patterns by either braced or
+unbraced hexadecimal escape sequences (for example, \ex{b3} or \exb3). Larger
+values have to use braced sequences.
+.P
+2. Octal numbers up to \e777 are recognized, and in UTF-8 mode they match
+two-byte characters for values greater than \e177.
+.P
+3. Repeat quantifiers apply to complete UTF characters, not to individual
+data units, for example: \ex{100}{3}.
+.P
+4. The dot metacharacter matches one UTF character instead of a single data
+unit.
+.P
+5. The escape sequence \eC can be used to match a single byte in UTF-8 mode, or
+a single 16-bit data unit in UTF-16 mode, or a single 32-bit data unit in
+UTF-32 mode, but its use can lead to some strange effects because it breaks up
+multi-unit characters (see the description of \eC in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+documentation). The use of \eC is not supported in the alternative matching
+function \fBpcre[16|32]_dfa_exec()\fP, nor is it supported in UTF mode by the
+JIT optimization of \fBpcre[16|32]_exec()\fP. If JIT optimization is requested
+for a UTF pattern that contains \eC, it will not succeed, and so the matching
+will be carried out by the normal interpretive function.
+.P
+6. The character escapes \eb, \eB, \ed, \eD, \es, \eS, \ew, and \eW correctly
+test characters of any code value, but, by default, the characters that PCRE
+recognizes as digits, spaces, or word characters remain the same set as in
+non-UTF mode, all with values less than 256. This remains true even when PCRE
+is built to include Unicode property support, because to do otherwise would
+slow down PCRE in many common cases. Note in particular that this applies to
+\eb and \eB, because they are defined in terms of \ew and \eW. If you really
+want to test for a wider sense of, say, "digit", you can use explicit Unicode
+property tests such as \ep{Nd}. Alternatively, if you set the PCRE_UCP option,
+the way that the character escapes work is changed so that Unicode properties
+are used to determine which characters match. There are more details in the
+section on
+.\" HTML 
+.\" 
+generic character types
+.\"
+in the
+.\" HREF
+\fBpcrepattern\fP
+.\"
+documentation.
+.P
+7. Similarly, characters that match the POSIX named character classes are all
+low-valued characters, unless the PCRE_UCP option is set.
+.P
+8. However, the horizontal and vertical white space matching escapes (\eh, \eH,
+\ev, and \eV) do match all the appropriate Unicode characters, whether or not
+PCRE_UCP is set.
+.P
+9. Case-insensitive matching applies only to characters whose values are less
+than 128, unless PCRE is built with Unicode property support. A few Unicode
+characters such as Greek sigma have more than two codepoints that are
+case-equivalent. Up to and including PCRE release 8.31, only one-to-one case
+mappings were supported, but later releases (with Unicode property support) do
+treat as case-equivalent all versions of characters such as Greek sigma.
+.
+.
+.SH AUTHOR
+.rs
+.sp
+.nf
+Philip Hazel
+University Computing Service
+Cambridge CB2 3QH, England.
+.fi
+.
+.
+.SH REVISION
+.rs
+.sp
+.nf
+Last updated: 27 February 2013
+Copyright (c) 1997-2013 University of Cambridge.
+.fi
diff --git a/doc/perltest.txt b/doc/perltest.txt
new file mode 100644
index 0000000..bb1a52a
--- /dev/null
+++ b/doc/perltest.txt
@@ -0,0 +1,42 @@
+The perltest program
+--------------------
+
+The perltest.pl script tests Perl's regular expressions; it has the same
+specification as pcretest, and so can be given identical input, except that
+input patterns can be followed only by Perl's lower case modifiers and certain
+other pcretest modifiers that are either handled or ignored:
+
+  /+   recognized and handled by perltest
+  /++  the second + is ignored
+  /8   recognized and handled by perltest
+  /J   ignored
+  /K   ignored
+  /W   ignored
+  /S   ignored
+  /SS  ignored
+  /Y   ignored
+
+The pcretest \Y escape in data lines is removed before matching. The data lines
+are processed as Perl double-quoted strings, so if they contain " $ or @
+characters, these have to be escaped. For this reason, all such characters in
+the Perl-compatible testinput1 file are escaped so that they can be used for
+perltest as well as for pcretest. The special upper case pattern modifiers such
+as /A that pcretest recognizes, and its special data line escapes, are not used
+in the Perl-compatible test file. The output should be identical, apart from
+the initial identifying banner.
+
+The perltest.pl script can also test UTF-8 features. It recognizes the special
+modifier /8 that pcretest uses to invoke UTF-8 functionality. The testinput4
+and testinput6 files can be fed to perltest to run compatible UTF-8 tests.
+However, it is necessary to add "use utf8; require Encode" to the script to
+make this work correctly. I have not managed to find a way to handle this
+automatically.
+
+The other testinput files are not suitable for feeding to perltest.pl, since
+they make use of the special upper case modifiers and escapes that pcretest
+uses to test certain features of PCRE. Some of these files also contain
+malformed regular expressions, in order to check that PCRE diagnoses them
+correctly.
+
+Philip Hazel
+January 2012
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