path: root/NEWS

Changes between release 2.4.4 (07Dec93) and release 2.4.3:

	- Fixed two serious bugs in scanning 8-bit characters.

	- Fixed bug in YY_USER_ACTION that caused it to be executed
	  inappropriately (on the scanner's on internal actions, and
	  with incorrect yytext/yyleng values).

	- Fixed bug in pointing yyin at a new file and resuming scanning.

	- Portability fix regarding min/max/abs macros conflicting with
	  function definitions in standard header files.

	- Added a virtual LexerError() method to the C++ yyFlexLexer class
	  for reporting error messages instead of always using cerr.

	- Added warning in flexdoc that the C++ scanning class is presently
	  experimental and subject to considerable change between major
	  releases.


Changes between release 2.4.3 (03Dec93) and release 2.4.2:

	- Fixed bug causing fatal scanner messages to fail to print.

	- Fixed things so FlexLexer.h can be included in other C++
	  sources.  One side-effect of this change is that -+ and -CF
	  are now incompatible.

	- libfl.a now supplies private versions of the the <string.h>/
	  <strings.h> string routines needed by flex and the scanners
	  it generates, to enhance portability to some BSD systems.

	- More robust solution to 2.4.2's flexfatal() bug fix.

	- Added ranlib of installed libfl.a.

	- Some lint tweaks.

	- NOTE: problems have been encountered attempting to build flex
	  C++ scanners using g++ version 2.5.X.  The problem is due to an
	  unfortunate heuristic in g++ 2.5.X that attempts to discern between
	  C and C++ headers.  Because FlexLexer.h is installed (by default)
	  in /usr/local/include and not /usr/local/lib/g++-include, g++ 2.5.X
	  decides that it's a C header :-(.  So if you have problems, install
	  the header in /usr/local/lib/g++-include instead.


Changes between release 2.4.2 (01Dec93) and release 2.4.1:

	- Fixed bug in libfl.a referring to non-existent "flexfatal" function.

	- Modified to produce both compress'd and gzip'd tar files for
	  distributions (you probably don't care about this change!).


Changes between release 2.4.1 (30Nov93) and release 2.3.8:

	- The new '-+' flag instructs flex to generate a C++ scanner class
	  (thanks to Kent Williams).  flex writes an implementation of the
	  class defined in FlexLexer.h to lex.yy.cc.  You may include
	  multiple scanner classes in your program using the -P flag.  Note
	  that the scanner class also provides a mechanism for creating
	  reentrant scanners.  The scanner class uses C++ streams for I/O
	  instead of FILE*'s (thanks to Tom Epperly).  If the flex executable's
	  name ends in '+' then the '-+' flag is automatically on, so creating
	  a symlink or copy of "flex" to "flex++" results in a version of
	  flex that can be used exclusively for C++ scanners.

	  Note that without the '-+' flag, flex-generated scanners can still
	  be compiled using C++ compilers, though they use FILE*'s for I/O
	  instead of streams.

	  See the "GENERATING C++ SCANNERS" section of flexdoc for details.

	- The new '-l' flag turns on maximum AT&T lex compatibility.  In
	  particular, -l includes support for "yylineno" and makes yytext
	  be an array instead of a pointer.  It does not, however, do away
	  with all incompatibilities.  See the "INCOMPATIBILITIES WITH LEX
	  AND POSIX" section of flexdoc for details.

	- The new '-P' option specifies a prefix to use other than "yy"
	  for the scanner's globally-visible variables, and for the
	  "lex.yy.c" filename.  Using -P you can link together multiple
	  flex scanners in the same executable.

	- The distribution includes a "texinfo" version of flexdoc.1,
	  contributed by Roland Pesch (thanks also to Marq Kole, who
	  contributed another version).  It has not been brought up to
	  date, but reflects version 2.3.  See MISC/flex.texinfo.

	  The flex distribution will soon include G.T. Nicol's flex
	  manual; he is presently bringing it up-to-date for version 2.4.

	- yywrap() is now a function, and you now *must* link flex scanners
	  with libfl.a.

	- Site-configuration is now done via an autoconf-generated
	  "configure" script contributed by Francois Pinard.

	- Scanners now use fread() (or getc(), if interactive) and not
	  read() for input.  A new "table compression" option, -Cr,
	  overrides this change and causes the scanner to use read()
	  (because read() is a bit faster than fread()).  -f and -F
	  are now equivalent to -Cfr and -CFr; i.e., they imply the
	  -Cr option.

	- In the blessed name of POSIX compliance, flex supports "%array"
	  and "%pointer" directives in the definitions (first) section of
	  the scanner specification.  The former specifies that yytext
	  should be an array (of size YYLMAX), the latter, that it should
	  be a pointer.  The array version of yytext is universally slower
	  than the pointer version, but has the advantage that its contents
	  remain unmodified across calls to input() and unput() (the pointer
	  version of yytext is, still, trashed by such calls).

	  "%array" cannot be used with the '-+' C++ scanner class option.

	- The new '-Ca' option directs flex to trade off memory for
	  natural alignment when generating a scanner's tables.  In
	  particular, table entries that would otherwise be "short"
	  become "long".

	- The new '-h' option produces a summary of the flex flags.

	- The new '-V' option reports the flex version number and exits.

	- The new scanner macro YY_START returns an integer value
	  corresponding to the current start condition.  You can return
	  to that start condition by passing the value to a subsequent
	  "BEGIN" action.  You also can implement "start condition stacks"
	  by storing the values in an integer stack.

	- You can now redefine macros such as YY_INPUT by just #define'ing
	  them to some other value in the first section of the flex input;
	  no need to first #undef them.

	- flex now generates warnings for rules that can't be matched.
	  These warnings can be turned off using the new '-w' flag.  If
	  your scanner uses REJECT then you will not get these warnings.

	- If you specify the '-s' flag but the default rule can be matched,
	  flex now generates a warning.

	- "yyleng" is now a global, and may be modified by the user (though
	  doing so and then using yymore() will yield weird results).

	- Name definitions in the first section of a scanner specification
	  can now include a leading '^' or trailing '$' operator.  In this
	  case, the definition is *not* pushed back inside of parentheses.

	- Scanners with compressed tables are now "interactive" (-I option)
	  by default.  You can suppress this attribute (which makes them
	  run slightly slower) using the new '-B' flag.

	- Flex now generates 8-bit scanners by default, unless you use the
	  -Cf or -CF compression options (-Cfe  and -CFe result in 8-bit
	  scanners).  You can force it to generate a 7-bit scanner using
	  the new '-7' flag.  You can build flex to generate 8-bit scanners
	  for -Cf and -CF, too, by adding -DDEFAULT_CSIZE=256 to CFLAGS
	  in the Makefile.

	- You no longer need to call the scanner routine yyrestart() to
	  inform the scanner that you have switched to a new file after
	  having seen an EOF on the current input file.  Instead, just
	  point yyin at the new file and continue scanning.

	- You no longer need to invoke YY_NEW_FILE in an <<EOF>> action
	  to indicate you wish to continue scanning.  Simply point yyin
	  at a new file.

	- A leading '#' no longer introduces a comment in a flex input.

	- flex no longer considers formfeed ('\f') a whitespace character.

	- %t, I'm happy to report, has been nuked.

	- The '-p' option may be given twice ('-pp') to instruct flex to
	  report minor performance problems as well as major ones.

	- The '-v' verbose output no longer includes start/finish time
	  information.

	- Newlines in flex inputs can optionally include leading or
	  trailing carriage-returns ('\r'), in support of several PC/Mac
	  run-time libraries that automatically include these.

	- A start condition of the form "<*>" makes the following rule
	  active in every start condition, whether exclusive or inclusive.

	- The following items have been corrected in the flex documentation:

		- '-C' table compression options *are* cumulative.

		- You may modify yytext but not lengthen it by appending
		  characters to the end.  Modifying its final character
		  will affect '^' anchoring for the next rule matched
		  if the character is changed to or from a newline.

		- The term "backtracking" has been renamed "backing up",
		  since it is a one-time repositioning and not a repeated
		  search.  What used to be the "lex.backtrack" file is now
		  "lex.backup".

		- Unindented "/* ... */" comments are allowed in the first
		  flex input section, but not in the second.

		- yyless() can only be used in the flex input source, not
		  externally.

		- You can use "yyrestart(yyin)" to throw away the
		  current contents of the input buffer.

		- To write high-speed scanners, attempt to match as much
		  text as possible with each rule.  See MISC/fastwc/README
		  for more information.

		- Using the beginning-of-line operator ('^') is fairly
		  cheap.  Using unput() is expensive.  Using yyless() is
		  cheap.

		- An example of scanning strings with embedded escape
		  sequences has been added.

		- The example of backing-up in flexdoc was erroneous; it
		  has been corrected.

	- A flex scanner's internal buffer now dynamically grows if needed
	  to match large tokens.  Note that growing the buffer presently
	  requires rescanning the (large) token, so consuming a lot of
	  text this way is a slow process.  Also note that presently the
	  buffer does *not* grow if you unput() more text than can fit
	  into the buffer.

	- The MISC/ directory has been reorganized; see MISC/README for
	  details.

	- yyless() can now be used in the third (user action) section
	  of a scanner specification, thanks to Ceriel Jacobs.  yyless()
	  remains a macro and cannot be used outside of the scanner source.

	- The skeleton file is no longer opened at run-time, but instead
	  compiled into a large string array (thanks to John Gilmore and
	  friends at Cygnus).  You can still use the -S flag to point flex
	  at a different skeleton file, though if you use this option let
	  me know, as I plan to otherwise do away with -S in the near
	  future.

	- flex no longer uses a temporary file to store the scanner's
	  actions.

	- A number of changes have been made to decrease porting headaches.
	  In particular, flex no longer uses memset() or ctime(), and
	  provides a single simple mechanism for dealing with C compilers
	  that still define malloc() as returning char* instead of void*.

	- Flex now detects if the scanner specification requires the -8 flag
	  but the flag was not given or on by default.

	- A number of table-expansion fencepost bugs have been fixed,
	  making flex more robust for generating large scanners.

	- flex more consistently identifies the location of errors in
	  its input.

	- YY_USER_ACTION is now invoked only for "real" actions, not for
	  internal actions used by the scanner for things like filling
	  the buffer or handling EOF.

	- The rule "[^]]" now matches any character other than a ']';
	  formerly it matched any character at all followed by a ']'.
	  This change was made for compatibility with AT&T lex.

	- A large number of miscellaneous bugs have been found and fixed
	  thanks to Gerhard Wilhelms.

	- The source code has been heavily reformatted, making patches
	  relative to previous flex releases no longer accurate.


Changes between 2.3 Patch #8 (21Feb93) and 2.3 Patch #7:

	- Fixed bugs in dynamic memory allocation leading to grievous
	  fencepost problems when generating large scanners.
	- Fixed bug causing infinite loops on character classes with 8-bit
	  characters in them.
	- Fixed bug in matching repetitions with a lower bound of 0.
	- Fixed bug in scanning NUL characters using an "interactive" scanner.
	- Fixed bug in using yymore() at the end of a file.
	- Fixed bug in misrecognizing rules with variable trailing context.
	- Fixed bug compiling flex on Suns using gcc 2.
	- Fixed bug in not recognizing that input files with the character
	  ASCII 128 in them require the -8 flag.
	- Fixed bug that could cause an infinite loop writing out
	  error messages.
	- Fixed bug in not recognizing old-style lex % declarations if
	  followed by a tab instead of a space.
	- Fixed potential crash when flex terminated early (usually due
	  to a bad flag) and the -v flag had been given.
	- Added some missing declarations of void functions.
	- Changed to only use '\a' for __STDC__ compilers.
	- Updated mailing addresses.


Changes between 2.3 Patch #7 (28Mar91) and 2.3 Patch #6:

	- Fixed out-of-bounds array access that caused bad tables
	  to be produced on machines where the bad reference happened
	  to yield a 1.  This caused problems installing or running
	  flex on some Suns, in particular.


Changes between 2.3 Patch #6 (29Aug90) and 2.3 Patch #5:

	- Fixed a serious bug in yymore() which basically made it
	  completely broken.  Thanks goes to Jean Christophe of
	  the Nethack development team for finding the problem
	  and passing along the fix.


Changes between 2.3 Patch #5 (16Aug90) and 2.3 Patch #4:

	- An up-to-date version of initscan.c so "make test" will
	  work after applying the previous patches


Changes between 2.3 Patch #4 (14Aug90) and 2.3 Patch #3:

	- Fixed bug in hexadecimal escapes which allowed only digits,
	  not letters, in escapes
	- Fixed bug in previous "Changes" file!


Changes between 2.3 Patch #3 (03Aug90) and 2.3 Patch #2:

	- Correction to patch #2 for gcc compilation; thanks goes to
	  Paul Eggert for catching this.


Changes between 2.3 Patch #2 (02Aug90) and original 2.3 release:

	- Fixed (hopefully) headaches involving declaring malloc()
	  and free() for gcc, which defines __STDC__ but (often) doesn't
	  come with the standard include files such as <stdlib.h>.
	  Reordered #ifdef maze in the scanner skeleton in the hope of
	  getting the declarations right for cfront and g++, too.

	- Note that this patch supercedes patch #1 for release 2.3,
	  which was never announced but was available briefly for
	  anonymous ftp.


Changes between 2.3 (full) release of 28Jun90 and 2.2 (alpha) release:

    User-visible:

	- A lone <<EOF>> rule (that is, one which is not qualified with
	  a list of start conditions) now specifies the EOF action for
	  *all* start conditions which haven't already had <<EOF>> actions
	  given.  To specify an end-of-file action for just the initial
	  state, use <INITIAL><<EOF>>.

	- -d debug output is now contigent on the global yy_flex_debug
	  being set to a non-zero value, which it is by default.

	- A new macro, YY_USER_INIT, is provided for the user to specify
	  initialization action to be taken on the first call to the
	  scanner.  This action is done before the scanner does its
	  own initialization.

	- yy_new_buffer() has been added as an alias for yy_create_buffer()

	- Comments beginning with '#' and extending to the end of the line
	  now work, but have been deprecated (in anticipation of making
	  flex recognize #line directives).

	- The funky restrictions on when semi-colons could follow the
	  YY_NEW_FILE and yyless macros have been removed.  They now
	  behave identically to functions.

	- A bug in the sample redefinition of YY_INPUT in the documentation
	  has been corrected.

	- A bug in the sample simple tokener in the documentation has
	  been corrected.

	- The documentation on the incompatibilities between flex and
	  lex has been reordered so that the discussion of yylineno
	  and input() come first, as it's anticipated that these will
	  be the most common source of headaches.


    Things which didn't used to be documented but now are:

	- flex interprets "^foo|bar" differently from lex.  flex interprets
	  it as "match either a 'foo' or a 'bar', providing it comes at the
	  beginning of a line", whereas lex interprets it as "match either
	  a 'foo' at the beginning of a line, or a 'bar' anywhere".

	- flex initializes the global "yyin" on the first call to the
	  scanner, while lex initializes it at compile-time.

	- yy_switch_to_buffer() can be used in the yywrap() macro/routine.

	- flex scanners do not use stdio for their input, and hence when
	  writing an interactive scanner one must explictly call fflush()
	  after writing out a prompt.

	- flex scanner can be made reentrant (after a fashion) by using
	  "yyrestart( yyin );".  This is useful for interactive scanners
	  which have interrupt handlers that long-jump out of the scanner.

	- a defense of why yylineno is not supported is included, along
	  with a suggestion on how to convert scanners which rely on it.


    Other changes:

	- Prototypes and proper declarations of void routines have
	  been added to the flex source code, courtesy of Kevin B. Kenny.

	- Routines dealing with memory allocation now use void* pointers
	  instead of char* - see Makefile for porting implications.

	- Error-checking is now done when flex closes a file.

	- Various lint tweaks were added to reduce the number of gripes.

	- Makefile has been further parameterized to aid in porting.

	- Support for SCO Unix added.

	- Flex now sports the latest & greatest UC copyright notice
	  (which is only slightly different from the previous one).

	- A note has been added to flexdoc.1 mentioning work in progress
	  on modifying flex to generate straight C code rather than a
	  table-driven automaton, with an email address of whom to contact
	  if you are working along similar lines.


Changes between 2.2 Patch #3 (30Mar90) and 2.2 Patch #2:

	- fixed bug which caused -I scanners to bomb


Changes between 2.2 Patch #2 (27Mar90) and 2.2 Patch #1:

	- fixed bug writing past end of input buffer in yyunput()
	- fixed bug detecting NUL's at the end of a buffer


Changes between 2.2 Patch #1 (23Mar90) and 2.2 (alpha) release:

	- Makefile fixes: definition of MAKE variable for systems
	  which don't have it; installation of flexdoc.1 along with
	  flex.1; fixed two bugs which could cause "bigtest" to fail.

	- flex.skel fix for compiling with g++.

	- README and flexdoc.1 no longer list an out-of-date BITNET address
	  for contacting me.

	- minor typos and formatting changes to flex.1 and flexdoc.1.


Changes between 2.2 (alpha) release of March '90 and previous release:

    User-visible:

	- Full user documentation now available.

	- Support for 8-bit scanners.

	- Scanners now accept NUL's.

	- A facility has been added for dealing with multiple
	  input buffers.

	- Two manual entries now.  One which fully describes flex
	  (rather than just its differences from lex), and the
	  other for quick(er) reference.

	- A number of changes to bring flex closer into compliance
	  with the latest POSIX lex draft:

		%t support
		flex now accepts multiple input files and concatenates
		    them together to form its input
		previous -c (compress) flag renamed -C
		do-nothing -c and -n flags added
		Any indented code or code within %{}'s in section 2 is
		    now copied to the output

	- yyleng is now a bona fide global integer.

	- -d debug information now gives the line number of the
	  matched rule instead of which number rule it was from
	  the beginning of the file.

	- -v output now includes a summary of the flags used to generate
	  the scanner.

	- unput() and yyrestart() are now globally callable.

	- yyrestart() no longer closes the previous value of yyin.

	- C++ support; generated scanners can be compiled with C++ compiler.

	- Primitive -lfl library added, containing default main()
	  which calls yylex().  A number of routines currently living
	  in the scanner skeleton will probably migrate to here
	  in the future (in particular, yywrap() will probably cease
	  to be a macro and instead be a function in the -lfl library).

	- Hexadecimal (\x) escape sequences added.

	- Support for MS-DOS, VMS, and Turbo-C integrated.

	- The %used/%unused operators have been deprecated.  They
	  may go away soon.


    Other changes:

	- Makefile enhanced for easier testing and installation.
	- The parser has been tweaked to detect some erroneous
	  constructions which previously were missed.
	- Scanner input buffer overflow is now detected.
	- Bugs with missing "const" declarations fixed.
	- Out-of-date Minix/Atari patches provided.
	- Scanners no longer require printf() unless FLEX_DEBUG is being used.
	- A subtle input() bug has been fixed.
	- Line numbers for "continued action" rules (those following
	  the special '|' action) are now correct.
	- unput() bug fixed; had been causing problems porting flex to VMS.
	- yymore() handling rewritten to fix bug with interaction
	  between yymore() and trailing context.
	- EOF in actions now generates an error message.
	- Bug involving -CFe and generating equivalence classes fixed.
	- Bug which made -CF be treated as -Cf fixed.
	- Support for SysV tmpnam() added.
	- Unused #define's for scanner no longer generated.
	- Error messages which are associated with a particular input
	  line are now all identified with their input line in standard
	  format.
	- % directives which are valid to lex but not to flex are
	  now ignored instead of generating warnings.
	- -DSYS_V flag can now also be specified -DUSG for System V
	  compilation.


Changes between 2.1 beta-test release of June '89 and previous release:

    User-visible:

	- -p flag generates a performance report to stderr.  The report
	  consists of comments regarding features of the scanner rules
	  which result in slower scanners.

	- -b flag generates backtracking information to lex.backtrack.
	  This is a list of scanner states which require backtracking
	  and the characters on which they do so.  By adding rules
	  one can remove backtracking states.  If all backtracking states
	  are eliminated, the generated scanner will run faster.
	  Backtracking is not yet documented in the manual entry.

	- Variable trailing context now works, i.e., one can have
	  rules like "(foo)*/[ \t]*bletch".  Some trailing context
	  patterns still cannot be properly matched and generate
	  error messages.  These are patterns where the ending of the
	  first part of the rule matches the beginning of the second
	  part, such as "zx*/xy*", where the 'x*' matches the 'x' at
	  the beginning of the trailing context.  Lex won't get these
	  patterns right either.

	- Faster scanners.

	- End-of-file rules.  The special rule "<<EOF>>" indicates
	  actions which are to be taken when an end-of-file is
	  encountered and yywrap() returns non-zero (i.e., indicates
	  no further files to process).  See manual entry for example.

	- The -r (reject used) flag is gone.  flex now scans the input
	  for occurrences of the string "REJECT" to determine if the
	  action is needed.  It tries to be intelligent about this but
	  can be fooled.  One can force the presence or absence of
	  REJECT by adding a line in the first section of the form
	  "%used REJECT" or "%unused REJECT".

	- yymore() has been implemented.  Similarly to REJECT, flex
	  detects the use of yymore(), which can be overridden using
	  "%used" or "%unused".

	- Patterns like "x{0,3}" now work (i.e., with lower-limit == 0).

	- Removed '\^x' for ctrl-x misfeature.

	- Added '\a' and '\v' escape sequences.

	- \<digits> now works for octal escape sequences; previously
	  \0<digits> was required.

	- Better error reporting; line numbers are associated with rules.

	- yyleng is a macro; it cannot be accessed outside of the
	  scanner source file.

	- yytext and yyleng should not be modified within a flex action.

	- Generated scanners #define the name FLEX_SCANNER.

	- Rules are internally separated by YY_BREAK in lex.yy.c rather
	  than break, to allow redefinition.

	- The macro YY_USER_ACTION can be redefined to provide an action
	  which is always executed prior to the matched rule's action.
	
	- yyrestart() is a new action which can be used to restart
	  the scanner after it has seen an end-of-file (a "real" one,
	  that is, one for which yywrap() returned non-zero).  It takes
	  a FILE* argument indicating a new file to scan and sets
	  things up so that a subsequent call to yylex() will start
	  scanning that file.

	- Internal scanner names all preceded by "yy_"

	- lex.yy.c is deleted if errors are encountered during processing.

	- Comments may be put in the first section of the input by preceding
	  them with '#'.



    Other changes:

	- Some portability-related bugs fixed, in particular for machines
	  with unsigned characters or sizeof( int* ) != sizeof( int ).
	  Also, tweaks for VMS and Microsoft C (MS-DOS), and identifiers all
	  trimmed to be 31 or fewer characters.  Shortened file names
	  for dinosaur OS's.  Checks for allocating > 64K memory
	  on 16 bit'ers.  Amiga tweaks.  Compiles using gcc on a Sun-3.
	- Compressed and fast scanner skeletons merged.
	- Skeleton header files done away with.
	- Generated scanner uses prototypes and "const" for __STDC__.
	- -DSV flag is now -DSYS_V for System V compilation.
	- Removed all references to FTL language.
	- Software now covered by BSD Copyright.
	- flex will replace lex in subsequent BSD releases.