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diff --git a/doc/flex.info-1 b/doc/flex.info-1 index 67314bd..b352758 100644 --- a/doc/flex.info-1 +++ b/doc/flex.info-1 @@ -1,15 +1,10 @@ -This is flex.info, produced by makeinfo version 4.13 from flex.texi. +This is flex.info, produced by makeinfo version 6.0 from flex.texi. -INFO-DIR-SECTION Programming -START-INFO-DIR-ENTRY -* flex: (flex). Fast lexical analyzer generator (lex replacement). -END-INFO-DIR-ENTRY - - The flex manual is placed under the same licensing conditions as the +The flex manual is placed under the same licensing conditions as the rest of flex: - Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2012 The -Flex Project. + Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2012 The Flex +Project. Copyright (C) 1990, 1997 The Regents of the University of California. All rights reserved. @@ -18,14 +13,14 @@ All rights reserved. Paxson. The United States Government has rights in this work pursuant to -contract no. DE-AC03-76SF00098 between the United States Department of +contract no. DE-AC03-76SF00098 between the United States Department of Energy and the University of California. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: - 1. Redistributions of source code must retain the above copyright + 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright @@ -40,6 +35,10 @@ without specific prior written permission. THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. +INFO-DIR-SECTION Programming +START-INFO-DIR-ENTRY +* flex: (flex). Fast lexical analyzer generator (lex replacement). +END-INFO-DIR-ENTRY File: flex.info, Node: Top, Next: Copyright, Prev: (dir), Up: (dir) @@ -47,214 +46,215 @@ File: flex.info, Node: Top, Next: Copyright, Prev: (dir), Up: (dir) flex **** -This manual describes `flex', a tool for generating programs that +This manual describes 'flex', a tool for generating programs that perform pattern-matching on text. The manual includes both tutorial and reference sections. - This edition of `The flex Manual' documents `flex' version 2.5.39. -It was last updated on 6 December 2012. + This edition of 'The flex Manual' documents 'flex' version 2.6.0. It +was last updated on 10 November 2015. This manual was written by Vern Paxson, Will Estes and John Millaway. * Menu: -* Copyright:: -* Reporting Bugs:: -* Introduction:: -* Simple Examples:: -* Format:: -* Patterns:: -* Matching:: -* Actions:: -* Generated Scanner:: -* Start Conditions:: -* Multiple Input Buffers:: -* EOF:: -* Misc Macros:: -* User Values:: -* Yacc:: -* Scanner Options:: -* Performance:: -* Cxx:: -* Reentrant:: -* Lex and Posix:: -* Memory Management:: -* Serialized Tables:: -* Diagnostics:: -* Limitations:: -* Bibliography:: -* FAQ:: -* Appendices:: -* Indices:: - - --- The Detailed Node Listing --- +* Copyright:: +* Reporting Bugs:: +* Introduction:: +* Simple Examples:: +* Format:: +* Patterns:: +* Matching:: +* Actions:: +* Generated Scanner:: +* Start Conditions:: +* Multiple Input Buffers:: +* EOF:: +* Misc Macros:: +* User Values:: +* Yacc:: +* Scanner Options:: +* Performance:: +* Cxx:: +* Reentrant:: +* Lex and Posix:: +* Memory Management:: +* Serialized Tables:: +* Diagnostics:: +* Limitations:: +* Bibliography:: +* FAQ:: +* Appendices:: +* Indices:: + + -- The Detailed Node Listing -- Format of the Input File -* Definitions Section:: -* Rules Section:: -* User Code Section:: -* Comments in the Input:: +* Definitions Section:: +* Rules Section:: +* User Code Section:: +* Comments in the Input:: Scanner Options -* Options for Specifying Filenames:: -* Options Affecting Scanner Behavior:: -* Code-Level And API Options:: -* Options for Scanner Speed and Size:: -* Debugging Options:: -* Miscellaneous Options:: +* Options for Specifying Filenames:: +* Options Affecting Scanner Behavior:: +* Code-Level And API Options:: +* Options for Scanner Speed and Size:: +* Debugging Options:: +* Miscellaneous Options:: Reentrant C Scanners -* Reentrant Uses:: -* Reentrant Overview:: -* Reentrant Example:: -* Reentrant Detail:: -* Reentrant Functions:: +* Reentrant Uses:: +* Reentrant Overview:: +* Reentrant Example:: +* Reentrant Detail:: +* Reentrant Functions:: The Reentrant API in Detail -* Specify Reentrant:: -* Extra Reentrant Argument:: -* Global Replacement:: -* Init and Destroy Functions:: -* Accessor Methods:: -* Extra Data:: -* About yyscan_t:: +* Specify Reentrant:: +* Extra Reentrant Argument:: +* Global Replacement:: +* Init and Destroy Functions:: +* Accessor Methods:: +* Extra Data:: +* About yyscan_t:: Memory Management -* The Default Memory Management:: -* Overriding The Default Memory Management:: -* A Note About yytext And Memory:: +* The Default Memory Management:: +* Overriding The Default Memory Management:: +* A Note About yytext And Memory:: Serialized Tables -* Creating Serialized Tables:: -* Loading and Unloading Serialized Tables:: -* Tables File Format:: +* Creating Serialized Tables:: +* Loading and Unloading Serialized Tables:: +* Tables File Format:: FAQ -* When was flex born?:: -* How do I expand backslash-escape sequences in C-style quoted strings?:: -* Why do flex scanners call fileno if it is not ANSI compatible?:: -* Does flex support recursive pattern definitions?:: -* How do I skip huge chunks of input (tens of megabytes) while using flex?:: -* Flex is not matching my patterns in the same order that I defined them.:: -* My actions are executing out of order or sometimes not at all.:: -* How can I have multiple input sources feed into the same scanner at the same time?:: -* Can I build nested parsers that work with the same input file?:: -* How can I match text only at the end of a file?:: -* How can I make REJECT cascade across start condition boundaries?:: -* Why cant I use fast or full tables with interactive mode?:: -* How much faster is -F or -f than -C?:: -* If I have a simple grammar cant I just parse it with flex?:: -* Why doesn't yyrestart() set the start state back to INITIAL?:: -* How can I match C-style comments?:: -* The period isn't working the way I expected.:: -* Can I get the flex manual in another format?:: -* Does there exist a "faster" NDFA->DFA algorithm?:: -* How does flex compile the DFA so quickly?:: -* How can I use more than 8192 rules?:: -* How do I abandon a file in the middle of a scan and switch to a new file?:: -* How do I execute code only during initialization (only before the first scan)?:: -* How do I execute code at termination?:: -* Where else can I find help?:: -* Can I include comments in the "rules" section of the file?:: -* I get an error about undefined yywrap().:: -* How can I change the matching pattern at run time?:: -* How can I expand macros in the input?:: -* How can I build a two-pass scanner?:: -* How do I match any string not matched in the preceding rules?:: -* I am trying to port code from AT&T lex that uses yysptr and yysbuf.:: -* Is there a way to make flex treat NULL like a regular character?:: -* Whenever flex can not match the input it says "flex scanner jammed".:: -* Why doesn't flex have non-greedy operators like perl does?:: -* Memory leak - 16386 bytes allocated by malloc.:: -* How do I track the byte offset for lseek()?:: -* How do I use my own I/O classes in a C++ scanner?:: -* How do I skip as many chars as possible?:: -* deleteme00:: -* Are certain equivalent patterns faster than others?:: -* Is backing up a big deal?:: -* Can I fake multi-byte character support?:: -* deleteme01:: -* Can you discuss some flex internals?:: -* unput() messes up yy_at_bol:: -* The | operator is not doing what I want:: -* Why can't flex understand this variable trailing context pattern?:: -* The ^ operator isn't working:: -* Trailing context is getting confused with trailing optional patterns:: -* Is flex GNU or not?:: -* ERASEME53:: -* I need to scan if-then-else blocks and while loops:: -* ERASEME55:: -* ERASEME56:: -* ERASEME57:: -* Is there a repository for flex scanners?:: -* How can I conditionally compile or preprocess my flex input file?:: -* Where can I find grammars for lex and yacc?:: -* I get an end-of-buffer message for each character scanned.:: -* unnamed-faq-62:: -* unnamed-faq-63:: -* unnamed-faq-64:: -* unnamed-faq-65:: -* unnamed-faq-66:: -* unnamed-faq-67:: -* unnamed-faq-68:: -* unnamed-faq-69:: -* unnamed-faq-70:: -* unnamed-faq-71:: -* unnamed-faq-72:: -* unnamed-faq-73:: -* unnamed-faq-74:: -* unnamed-faq-75:: -* unnamed-faq-76:: -* unnamed-faq-77:: -* unnamed-faq-78:: -* unnamed-faq-79:: -* unnamed-faq-80:: -* unnamed-faq-81:: -* unnamed-faq-82:: -* unnamed-faq-83:: -* unnamed-faq-84:: -* unnamed-faq-85:: -* unnamed-faq-86:: -* unnamed-faq-87:: -* unnamed-faq-88:: -* unnamed-faq-90:: -* unnamed-faq-91:: -* unnamed-faq-92:: -* unnamed-faq-93:: -* unnamed-faq-94:: -* unnamed-faq-95:: -* unnamed-faq-96:: -* unnamed-faq-97:: -* unnamed-faq-98:: -* unnamed-faq-99:: -* unnamed-faq-100:: -* unnamed-faq-101:: +* When was flex born?:: +* How do I expand backslash-escape sequences in C-style quoted strings?:: +* Why do flex scanners call fileno if it is not ANSI compatible?:: +* Does flex support recursive pattern definitions?:: +* How do I skip huge chunks of input (tens of megabytes) while using flex?:: +* Flex is not matching my patterns in the same order that I defined them.:: +* My actions are executing out of order or sometimes not at all.:: +* How can I have multiple input sources feed into the same scanner at the same time?:: +* Can I build nested parsers that work with the same input file?:: +* How can I match text only at the end of a file?:: +* How can I make REJECT cascade across start condition boundaries?:: +* Why cant I use fast or full tables with interactive mode?:: +* How much faster is -F or -f than -C?:: +* If I have a simple grammar cant I just parse it with flex?:: +* Why doesn't yyrestart() set the start state back to INITIAL?:: +* How can I match C-style comments?:: +* The period isn't working the way I expected.:: +* Can I get the flex manual in another format?:: +* Does there exist a "faster" NDFA->DFA algorithm?:: +* How does flex compile the DFA so quickly?:: +* How can I use more than 8192 rules?:: +* How do I abandon a file in the middle of a scan and switch to a new file?:: +* How do I execute code only during initialization (only before the first scan)?:: +* How do I execute code at termination?:: +* Where else can I find help?:: +* Can I include comments in the "rules" section of the file?:: +* I get an error about undefined yywrap().:: +* How can I change the matching pattern at run time?:: +* How can I expand macros in the input?:: +* How can I build a two-pass scanner?:: +* How do I match any string not matched in the preceding rules?:: +* I am trying to port code from AT&T lex that uses yysptr and yysbuf.:: +* Is there a way to make flex treat NULL like a regular character?:: +* Whenever flex can not match the input it says "flex scanner jammed".:: +* Why doesn't flex have non-greedy operators like perl does?:: +* Memory leak - 16386 bytes allocated by malloc.:: +* How do I track the byte offset for lseek()?:: +* How do I use my own I/O classes in a C++ scanner?:: +* How do I skip as many chars as possible?:: +* deleteme00:: +* Are certain equivalent patterns faster than others?:: +* Is backing up a big deal?:: +* Can I fake multi-byte character support?:: +* deleteme01:: +* Can you discuss some flex internals?:: +* unput() messes up yy_at_bol:: +* The | operator is not doing what I want:: +* Why can't flex understand this variable trailing context pattern?:: +* The ^ operator isn't working:: +* Trailing context is getting confused with trailing optional patterns:: +* Is flex GNU or not?:: +* ERASEME53:: +* I need to scan if-then-else blocks and while loops:: +* ERASEME55:: +* ERASEME56:: +* ERASEME57:: +* Is there a repository for flex scanners?:: +* How can I conditionally compile or preprocess my flex input file?:: +* Where can I find grammars for lex and yacc?:: +* I get an end-of-buffer message for each character scanned.:: +* unnamed-faq-62:: +* unnamed-faq-63:: +* unnamed-faq-64:: +* unnamed-faq-65:: +* unnamed-faq-66:: +* unnamed-faq-67:: +* unnamed-faq-68:: +* unnamed-faq-69:: +* unnamed-faq-70:: +* unnamed-faq-71:: +* unnamed-faq-72:: +* unnamed-faq-73:: +* unnamed-faq-74:: +* unnamed-faq-75:: +* unnamed-faq-76:: +* unnamed-faq-77:: +* unnamed-faq-78:: +* unnamed-faq-79:: +* unnamed-faq-80:: +* unnamed-faq-81:: +* unnamed-faq-82:: +* unnamed-faq-83:: +* unnamed-faq-84:: +* unnamed-faq-85:: +* unnamed-faq-86:: +* unnamed-faq-87:: +* unnamed-faq-88:: +* unnamed-faq-90:: +* unnamed-faq-91:: +* unnamed-faq-92:: +* unnamed-faq-93:: +* unnamed-faq-94:: +* unnamed-faq-95:: +* unnamed-faq-96:: +* unnamed-faq-97:: +* unnamed-faq-98:: +* unnamed-faq-99:: +* unnamed-faq-100:: +* unnamed-faq-101:: * What is the difference between YYLEX_PARAM and YY_DECL?:: * Why do I get "conflicting types for yylex" error?:: * How do I access the values set in a Flex action from within a Bison action?:: Appendices -* Makefiles and Flex:: -* Bison Bridge:: -* M4 Dependency:: -* Common Patterns:: +* Makefiles and Flex:: +* Bison Bridge:: +* M4 Dependency:: +* Common Patterns:: Indices -* Concept Index:: -* Index of Functions and Macros:: -* Index of Variables:: -* Index of Data Types:: -* Index of Hooks:: -* Index of Scanner Options:: +* Concept Index:: +* Index of Functions and Macros:: +* Index of Variables:: +* Index of Data Types:: +* Index of Hooks:: +* Index of Scanner Options:: + File: flex.info, Node: Copyright, Next: Reporting Bugs, Prev: Top, Up: Top @@ -265,8 +265,8 @@ File: flex.info, Node: Copyright, Next: Reporting Bugs, Prev: Top, Up: Top The flex manual is placed under the same licensing conditions as the rest of flex: - Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2012 The -Flex Project. + Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2012 The Flex +Project. Copyright (C) 1990, 1997 The Regents of the University of California. All rights reserved. @@ -275,14 +275,14 @@ All rights reserved. Paxson. The United States Government has rights in this work pursuant to -contract no. DE-AC03-76SF00098 between the United States Department of +contract no. DE-AC03-76SF00098 between the United States Department of Energy and the University of California. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: - 1. Redistributions of source code must retain the above copyright + 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright @@ -304,7 +304,7 @@ File: flex.info, Node: Reporting Bugs, Next: Introduction, Prev: Copyright, 2 Reporting Bugs **************** -If you find a bug in `flex', please report it using the SourceForge Bug +If you find a bug in 'flex', please report it using the SourceForge Bug Tracking facilities which can be found on flex's SourceForge Page (http://sourceforge.net/projects/flex). @@ -314,17 +314,17 @@ File: flex.info, Node: Introduction, Next: Simple Examples, Prev: Reporting B 3 Introduction ************** -`flex' is a tool for generating "scanners". A scanner is a program -which recognizes lexical patterns in text. The `flex' program reads -the given input files, or its standard input if no file names are -given, for a description of a scanner to generate. The description is -in the form of pairs of regular expressions and C code, called "rules". -`flex' generates as output a C source file, `lex.yy.c' by default, -which defines a routine `yylex()'. This file can be compiled and -linked with the flex runtime library to produce an executable. When -the executable is run, it analyzes its input for occurrences of the -regular expressions. Whenever it finds one, it executes the -corresponding C code. +'flex' is a tool for generating "scanners". A scanner is a program +which recognizes lexical patterns in text. The 'flex' program reads the +given input files, or its standard input if no file names are given, for +a description of a scanner to generate. The description is in the form +of pairs of regular expressions and C code, called "rules". 'flex' +generates as output a C source file, 'lex.yy.c' by default, which +defines a routine 'yylex()'. This file can be compiled and linked with +the flex runtime library to produce an executable. When the executable +is run, it analyzes its input for occurrences of the regular +expressions. Whenever it finds one, it executes the corresponding C +code. File: flex.info, Node: Simple Examples, Next: Format, Prev: Introduction, Up: Top @@ -332,21 +332,20 @@ File: flex.info, Node: Simple Examples, Next: Format, Prev: Introduction, Up 4 Some Simple Examples ********************** -First some simple examples to get the flavor of how one uses `flex'. +First some simple examples to get the flavor of how one uses 'flex'. - The following `flex' input specifies a scanner which, when it -encounters the string `username' will replace it with the user's login + The following 'flex' input specifies a scanner which, when it +encounters the string 'username' will replace it with the user's login name: %% username printf( "%s", getlogin() ); - By default, any text not matched by a `flex' scanner is copied to -the output, so the net effect of this scanner is to copy its input file -to its output with each occurrence of `username' expanded. In this -input, there is just one rule. `username' is the "pattern" and the -`printf' is the "action". The `%%' symbol marks the beginning of the -rules. + By default, any text not matched by a 'flex' scanner is copied to the +output, so the net effect of this scanner is to copy its input file to +its output with each occurrence of 'username' expanded. In this input, +there is just one rule. 'username' is the "pattern" and the 'printf' is +the "action". The '%%' symbol marks the beginning of the rules. Here's another simple example: @@ -366,13 +365,13 @@ rules. } This scanner counts the number of characters and the number of lines -in its input. It produces no output other than the final report on the +in its input. It produces no output other than the final report on the character and line counts. The first line declares two globals, -`num_lines' and `num_chars', which are accessible both inside `yylex()' -and in the `main()' routine declared after the second `%%'. There are -two rules, one which matches a newline (`\n') and increments both the +'num_lines' and 'num_chars', which are accessible both inside 'yylex()' +and in the 'main()' routine declared after the second '%%'. There are +two rules, one which matches a newline ('\n') and increments both the line count and the character count, and one which matches any character -other than a newline (indicated by the `.' regular expression). +other than a newline (indicated by the '.' regular expression). A somewhat more complicated example: @@ -438,8 +437,8 @@ File: flex.info, Node: Format, Next: Patterns, Prev: Simple Examples, Up: To 5 Format of the Input File ************************** -The `flex' input file consists of three sections, separated by a line -containing only `%%'. +The 'flex' input file consists of three sections, separated by a line +containing only '%%'. definitions %% @@ -449,10 +448,10 @@ containing only `%%'. * Menu: -* Definitions Section:: -* Rules Section:: -* User Code Section:: -* Comments in the Input:: +* Definitions Section:: +* Rules Section:: +* User Code Section:: +* Comments in the Input:: File: flex.info, Node: Definitions Section, Next: Rules Section, Prev: Format, Up: Format @@ -468,18 +467,18 @@ definitions to simplify the scanner specification, and declarations of name definition - The `name' is a word beginning with a letter or an underscore (`_') -followed by zero or more letters, digits, `_', or `-' (dash). The + The 'name' is a word beginning with a letter or an underscore ('_') +followed by zero or more letters, digits, '_', or '-' (dash). The definition is taken to begin at the first non-whitespace character following the name and continuing to the end of the line. The -definition can subsequently be referred to using `{name}', which will -expand to `(definition)'. For example, +definition can subsequently be referred to using '{name}', which will +expand to '(definition)'. For example, DIGIT [0-9] ID [a-z][a-z0-9]* - Defines `DIGIT' to be a regular expression which matches a single -digit, and `ID' to be a regular expression which matches a letter + Defines 'DIGIT' to be a regular expression which matches a single +digit, and 'ID' to be a regular expression which matches a letter followed by zero-or-more letters-or-digits. A subsequent reference to {DIGIT}+"."{DIGIT}* @@ -488,22 +487,22 @@ followed by zero-or-more letters-or-digits. A subsequent reference to ([0-9])+"."([0-9])* - and matches one-or-more digits followed by a `.' followed by + and matches one-or-more digits followed by a '.' followed by zero-or-more digits. - An unindented comment (i.e., a line beginning with `/*') is copied -verbatim to the output up to the next `*/'. + An unindented comment (i.e., a line beginning with '/*') is copied +verbatim to the output up to the next '*/'. - Any _indented_ text or text enclosed in `%{' and `%}' is also copied -verbatim to the output (with the %{ and %} symbols removed). The %{ -and %} symbols must appear unindented on lines by themselves. + Any _indented_ text or text enclosed in '%{' and '%}' is also copied +verbatim to the output (with the %{ and %} symbols removed). The %{ and +%} symbols must appear unindented on lines by themselves. - A `%top' block is similar to a `%{' ... `%}' block, except that the -code in a `%top' block is relocated to the _top_ of the generated file, -before any flex definitions (1). The `%top' block is useful when you + A '%top' block is similar to a '%{' ... '%}' block, except that the +code in a '%top' block is relocated to the _top_ of the generated file, +before any flex definitions (1). The '%top' block is useful when you want certain preprocessor macros to be defined or certain files to be -included before the generated code. The single characters, `{' and -`}' are used to delimit the `%top' block, as show in the example below: +included before the generated code. The single characters, '{' and '}' +are used to delimit the '%top' block, as show in the example below: %top{ /* This code goes at the "top" of the generated file. */ @@ -511,11 +510,11 @@ included before the generated code. The single characters, `{' and #include <inttypes.h> } - Multiple `%top' blocks are allowed, and their order is preserved. + Multiple '%top' blocks are allowed, and their order is preserved. ---------- Footnotes ---------- - (1) Actually, `yyIN_HEADER' is defined before the `%top' block. + (1) Actually, 'yyIN_HEADER' is defined before the '%top' block. File: flex.info, Node: Rules Section, Next: User Code Section, Prev: Definitions Section, Up: Format @@ -523,27 +522,27 @@ File: flex.info, Node: Rules Section, Next: User Code Section, Prev: Definiti 5.2 Format of the Rules Section =============================== -The "rules" section of the `flex' input contains a series of rules of +The "rules" section of the 'flex' input contains a series of rules of the form: pattern action - where the pattern must be unindented and the action must begin on -the same line. *Note Patterns::, for a further description of patterns -and actions. + where the pattern must be unindented and the action must begin on the +same line. *Note Patterns::, for a further description of patterns and +actions. In the rules section, any indented or %{ %} enclosed text appearing before the first rule may be used to declare variables which are local to the scanning routine and (after the declarations) code which is to be -executed whenever the scanning routine is entered. Other indented or -%{ %} text in the rule section is still copied to the output, but its +executed whenever the scanning routine is entered. Other indented or %{ +%} text in the rule section is still copied to the output, but its meaning is not well-defined and it may well cause compile-time errors -(this feature is present for POSIX compliance. *Note Lex and Posix::, +(this feature is present for POSIX compliance. *Note Lex and Posix::, for other such features). - Any _indented_ text or text enclosed in `%{' and `%}' is copied -verbatim to the output (with the %{ and %} symbols removed). The %{ -and %} symbols must appear unindented on lines by themselves. + Any _indented_ text or text enclosed in '%{' and '%}' is copied +verbatim to the output (with the %{ and %} symbols removed). The %{ and +%} symbols must appear unindented on lines by themselves. File: flex.info, Node: User Code Section, Next: Comments in the Input, Prev: Rules Section, Up: Format @@ -551,10 +550,10 @@ File: flex.info, Node: User Code Section, Next: Comments in the Input, Prev: 5.3 Format of the User Code Section =================================== -The user code section is simply copied to `lex.yy.c' verbatim. It is +The user code section is simply copied to 'lex.yy.c' verbatim. It is used for companion routines which call or are called by the scanner. The presence of this section is optional; if it is missing, the second -`%%' in the input file may be skipped, too. +'%%' in the input file may be skipped, too. File: flex.info, Node: Comments in the Input, Prev: User Code Section, Up: Format @@ -562,22 +561,21 @@ File: flex.info, Node: Comments in the Input, Prev: User Code Section, Up: Fo 5.4 Comments in the Input ========================= -Flex supports C-style comments, that is, anything between `/*' and `*/' -is considered a comment. Whenever flex encounters a comment, it copies -the entire comment verbatim to the generated source code. Comments may +Flex supports C-style comments, that is, anything between '/*' and '*/' +is considered a comment. Whenever flex encounters a comment, it copies +the entire comment verbatim to the generated source code. Comments may appear just about anywhere, but with the following exceptions: * Comments may not appear in the Rules Section wherever flex is - expecting a regular expression. This means comments may not appear + expecting a regular expression. This means comments may not appear at the beginning of a line, or immediately following a list of scanner states. - - * Comments may not appear on an `%option' line in the Definitions + * Comments may not appear on an '%option' line in the Definitions Section. If you want to follow a simple rule, then always begin a comment on a new line, with one or more whitespace characters before the initial -`/*'). This rule will work anywhere in the input file. +'/*'). This rule will work anywhere in the input file. All the comments in the following example are valid: @@ -602,6 +600,7 @@ new line, with one or more whitespace characters before the initial %% /* User Code Section */ + File: flex.info, Node: Patterns, Next: Matching, Prev: Format, Up: Top @@ -611,84 +610,84 @@ File: flex.info, Node: Patterns, Next: Matching, Prev: Format, Up: Top The patterns in the input (see *note Rules Section::) are written using an extended set of regular expressions. These are: -`x' +'x' match the character 'x' -`.' +'.' any character (byte) except newline -`[xyz]' +'[xyz]' a "character class"; in this case, the pattern matches either an 'x', a 'y', or a 'z' -`[abj-oZ]' +'[abj-oZ]' a "character class" with a range in it; matches an 'a', a 'b', any letter from 'j' through 'o', or a 'Z' -`[^A-Z]' +'[^A-Z]' a "negated character class", i.e., any character but those in the class. In this case, any character EXCEPT an uppercase letter. -`[^A-Z\n]' +'[^A-Z\n]' any character EXCEPT an uppercase letter or a newline -`[a-z]{-}[aeiou]' +'[a-z]{-}[aeiou]' the lowercase consonants -`r*' +'r*' zero or more r's, where r is any regular expression -`r+' +'r+' one or more r's -`r?' +'r?' zero or one r's (that is, "an optional r") -`r{2,5}' +'r{2,5}' anywhere from two to five r's -`r{2,}' +'r{2,}' two or more r's -`r{4}' +'r{4}' exactly 4 r's -`{name}' - the expansion of the `name' definition (*note Format::). +'{name}' + the expansion of the 'name' definition (*note Format::). -`"[xyz]\"foo"' - the literal string: `[xyz]"foo' +'"[xyz]\"foo"' + the literal string: '[xyz]"foo' -`\X' - if X is `a', `b', `f', `n', `r', `t', or `v', then the ANSI-C - interpretation of `\x'. Otherwise, a literal `X' (used to escape - operators such as `*') +'\X' + if X is 'a', 'b', 'f', 'n', 'r', 't', or 'v', then the ANSI-C + interpretation of '\x'. Otherwise, a literal 'X' (used to escape + operators such as '*') -`\0' +'\0' a NUL character (ASCII code 0) -`\123' +'\123' the character with octal value 123 -`\x2a' +'\x2a' the character with hexadecimal value 2a -`(r)' - match an `r'; parentheses are used to override precedence (see +'(r)' + match an 'r'; parentheses are used to override precedence (see below) -`(?r-s:pattern)' - apply option `r' and omit option `s' while interpreting pattern. - Options may be zero or more of the characters `i', `s', or `x'. +'(?r-s:pattern)' + apply option 'r' and omit option 's' while interpreting pattern. + Options may be zero or more of the characters 'i', 's', or 'x'. - `i' means case-insensitive. `-i' means case-sensitive. + 'i' means case-insensitive. '-i' means case-sensitive. - `s' alters the meaning of the `.' syntax to match any single byte - whatsoever. `-s' alters the meaning of `.' to match any byte - except `\n'. + 's' alters the meaning of the '.' syntax to match any single byte + whatsoever. '-s' alters the meaning of '.' to match any byte + except '\n'. - `x' ignores comments and whitespace in patterns. Whitespace is - ignored unless it is backslash-escaped, contained within `""'s, or + 'x' ignores comments and whitespace in patterns. Whitespace is + ignored unless it is backslash-escaped, contained within '""'s, or appears inside a character class. The following are all valid: @@ -708,66 +707,66 @@ an extended set of regular expressions. These are: b c) same as (abc) -`(?# comment )' - omit everything within `()'. The first `)' character encountered - ends the pattern. It is not possible to for the comment to contain - a `)' character. The comment may span lines. +'(?# comment )' + omit everything within '()'. The first ')' character encountered + ends the pattern. It is not possible to for the comment to contain + a ')' character. The comment may span lines. -`rs' - the regular expression `r' followed by the regular expression `s'; +'rs' + the regular expression 'r' followed by the regular expression 's'; called "concatenation" -`r|s' - either an `r' or an `s' +'r|s' + either an 'r' or an 's' -`r/s' - an `r' but only if it is followed by an `s'. The text matched by - `s' is included when determining whether this rule is the longest +'r/s' + an 'r' but only if it is followed by an 's'. The text matched by + 's' is included when determining whether this rule is the longest match, but is then returned to the input before the action is - executed. So the action only sees the text matched by `r'. This + executed. So the action only sees the text matched by 'r'. This type of pattern is called "trailing context". (There are some - combinations of `r/s' that flex cannot match correctly. *Note + combinations of 'r/s' that flex cannot match correctly. *Note Limitations::, regarding dangerous trailing context.) -`^r' - an `r', but only at the beginning of a line (i.e., when just +'^r' + an 'r', but only at the beginning of a line (i.e., when just starting to scan, or right after a newline has been scanned). -`r$' - an `r', but only at the end of a line (i.e., just before a - newline). Equivalent to `r/\n'. +'r$' + an 'r', but only at the end of a line (i.e., just before a + newline). Equivalent to 'r/\n'. - Note that `flex''s notion of "newline" is exactly whatever the C - compiler used to compile `flex' interprets `\n' as; in particular, - on some DOS systems you must either filter out `\r's in the input - yourself, or explicitly use `r/\r\n' for `r$'. + Note that 'flex''s notion of "newline" is exactly whatever the C + compiler used to compile 'flex' interprets '\n' as; in particular, + on some DOS systems you must either filter out '\r's in the input + yourself, or explicitly use 'r/\r\n' for 'r$'. -`<s>r' - an `r', but only in start condition `s' (see *note Start +'<s>r' + an 'r', but only in start condition 's' (see *note Start Conditions:: for discussion of start conditions). -`<s1,s2,s3>r' - same, but in any of start conditions `s1', `s2', or `s3'. +'<s1,s2,s3>r' + same, but in any of start conditions 's1', 's2', or 's3'. -`<*>r' - an `r' in any start condition, even an exclusive one. +'<*>r' + an 'r' in any start condition, even an exclusive one. -`<<EOF>>' +'<<EOF>>' an end-of-file. -`<s1,s2><<EOF>>' - an end-of-file when in start condition `s1' or `s2' +'<s1,s2><<EOF>>' + an end-of-file when in start condition 's1' or 's2' Note that inside of a character class, all regular expression -operators lose their special meaning except escape (`\') and the -character class operators, `-', `]]', and, at the beginning of the -class, `^'. +operators lose their special meaning except escape ('\') and the +character class operators, '-', ']]', and, at the beginning of the +class, '^'. The regular expressions listed above are grouped according to precedence, from highest precedence at the top to lowest at the bottom. Those grouped together have equal precedence (see special note on the -precedence of the repeat operator, `{}', under the documentation for -the `--posix' POSIX compliance option). For example, +precedence of the repeat operator, '{}', under the documentation for the +'--posix' POSIX compliance option). For example, foo|bar* @@ -775,23 +774,23 @@ the `--posix' POSIX compliance option). For example, (foo)|(ba(r*)) - since the `*' operator has higher precedence than concatenation, and -concatenation higher than alternation (`|'). This pattern therefore -matches _either_ the string `foo' _or_ the string `ba' followed by -zero-or-more `r''s. To match `foo' or zero-or-more repetitions of the -string `bar', use: + since the '*' operator has higher precedence than concatenation, and +concatenation higher than alternation ('|'). This pattern therefore +matches _either_ the string 'foo' _or_ the string 'ba' followed by +zero-or-more 'r''s. To match 'foo' or zero-or-more repetitions of the +string 'bar', use: foo|(bar)* - And to match a sequence of zero or more repetitions of `foo' and -`bar': + And to match a sequence of zero or more repetitions of 'foo' and +'bar': (foo|bar)* In addition to characters and ranges of characters, character classes can also contain "character class expressions". These are expressions -enclosed inside `[': and `:]' delimiters (which themselves must appear -between the `[' and `]' of the character class. Other elements may +enclosed inside '[:' and ':]' delimiters (which themselves must appear +between the '[' and ']' of the character class. Other elements may occur inside the character class, too). The valid expressions are: [:alnum:] [:alpha:] [:blank:] @@ -800,10 +799,10 @@ occur inside the character class, too). The valid expressions are: [:space:] [:upper:] [:xdigit:] These expressions all designate a set of characters equivalent to the -corresponding standard C `isXXX' function. For example, `[:alnum:]' -designates those characters for which `isalnum()' returns true - i.e., +corresponding standard C 'isXXX' function. For example, '[:alnum:]' +designates those characters for which 'isalnum()' returns true - i.e., any alphabetic or numeric character. Some systems don't provide -`isblank()', so flex defines `[:blank:]' as a blank or a tab. +'isblank()', so flex defines '[:blank:]' as a blank or a tab. For example, the following character classes are all equivalent: @@ -812,76 +811,77 @@ any alphabetic or numeric character. Some systems don't provide [[:alpha:][0-9]] [a-zA-Z0-9] - A word of caution. Character classes are expanded immediately when -seen in the `flex' input. This means the character classes are -sensitive to the locale in which `flex' is executed, and the resulting + A word of caution. Character classes are expanded immediately when +seen in the 'flex' input. This means the character classes are +sensitive to the locale in which 'flex' is executed, and the resulting scanner will not be sensitive to the runtime locale. This may or may not be desirable. - * If your scanner is case-insensitive (the `-i' flag), then - `[:upper:]' and `[:lower:]' are equivalent to `[:alpha:]'. + * If your scanner is case-insensitive (the '-i' flag), then + '[:upper:]' and '[:lower:]' are equivalent to '[:alpha:]'. - * Character classes with ranges, such as `[a-Z]', should be used with + * Character classes with ranges, such as '[a-Z]', should be used with caution in a case-insensitive scanner if the range spans upper or - lowercase characters. Flex does not know if you want to fold all - upper and lowercase characters together, or if you want the - literal numeric range specified (with no case folding). When in - doubt, flex will assume that you meant the literal numeric range, - and will issue a warning. The exception to this rule is a - character range such as `[a-z]' or `[S-W]' where it is obvious - that you want case-folding to occur. Here are some examples with - the `-i' flag enabled: + lowercase characters. Flex does not know if you want to fold all + upper and lowercase characters together, or if you want the literal + numeric range specified (with no case folding). When in doubt, + flex will assume that you meant the literal numeric range, and will + issue a warning. The exception to this rule is a character range + such as '[a-z]' or '[S-W]' where it is obvious that you want + case-folding to occur. Here are some examples with the '-i' flag + enabled: Range Result Literal Range Alternate Range - `[a-t]' ok `[a-tA-T]' - `[A-T]' ok `[a-tA-T]' - `[A-t]' ambiguous `[A-Z\[\\\]_`a-t]' `[a-tA-T]' - `[_-{]' ambiguous `[_`a-z{]' `[_`a-zA-Z{]' - `[@-C]' ambiguous `[@ABC]' `[@A-Z\[\\\]_`abc]' - - * A negated character class such as the example `[^A-Z]' above - _will_ match a newline unless `\n' (or an equivalent escape - sequence) is one of the characters explicitly present in the - negated character class (e.g., `[^A-Z\n]'). This is unlike how - many other regular expression tools treat negated character - classes, but unfortunately the inconsistency is historically - entrenched. Matching newlines means that a pattern like `[^"]*' - can match the entire input unless there's another quote in the - input. + '[a-t]' ok '[a-tA-T]' + '[A-T]' ok '[a-tA-T]' + '[A-t]' ambiguous '[A-Z\[\\\]_`a-t]' '[a-tA-T]' + '[_-{]' ambiguous '[_`a-z{]' '[_`a-zA-Z{]' + '[@-C]' ambiguous '[@ABC]' '[@A-Z\[\\\]_`abc]' + + * A negated character class such as the example '[^A-Z]' above _will_ + match a newline unless '\n' (or an equivalent escape sequence) is + one of the characters explicitly present in the negated character + class (e.g., '[^A-Z\n]'). This is unlike how many other regular + expression tools treat negated character classes, but unfortunately + the inconsistency is historically entrenched. Matching newlines + means that a pattern like '[^"]*' can match the entire input unless + there's another quote in the input. Flex allows negation of character class expressions by prepending - `^' to the POSIX character class name. + '^' to the POSIX character class name. [:^alnum:] [:^alpha:] [:^blank:] [:^cntrl:] [:^digit:] [:^graph:] [:^lower:] [:^print:] [:^punct:] [:^space:] [:^upper:] [:^xdigit:] - Flex will issue a warning if the expressions `[:^upper:]' and - `[:^lower:]' appear in a case-insensitive scanner, since their - meaning is unclear. The current behavior is to skip them entirely, + Flex will issue a warning if the expressions '[:^upper:]' and + '[:^lower:]' appear in a case-insensitive scanner, since their + meaning is unclear. The current behavior is to skip them entirely, but this may change without notice in future revisions of flex. - * The `{-}' operator computes the difference of two character - classes. For example, `[a-c]{-}[b-z]' represents all the - characters in the class `[a-c]' that are not in the class `[b-z]' - (which in this case, is just the single character `a'). The `{-}' - operator is left associative, so `[abc]{-}[b]{-}[c]' is the same - as `[a]'. Be careful not to accidentally create an empty set, - which will never match. - - * The `{+}' operator computes the union of two character classes. - For example, `[a-z]{+}[0-9]' is the same as `[a-z0-9]'. This + * + The '{-}' operator computes the difference of two character + classes. For example, '[a-c]{-}[b-z]' represents all the + characters in the class '[a-c]' that are not in the class '[b-z]' + (which in this case, is just the single character 'a'). The '{-}' + operator is left associative, so '[abc]{-}[b]{-}[c]' is the same as + '[a]'. Be careful not to accidentally create an empty set, which + will never match. + + * + The '{+}' operator computes the union of two character classes. + For example, '[a-z]{+}[0-9]' is the same as '[a-z0-9]'. This operator is useful when preceded by the result of a difference - operation, as in, `[[:alpha:]]{-}[[:lower:]]{+}[q]', which is - equivalent to `[A-Zq]' in the "C" locale. - - * A rule can have at most one instance of trailing context (the `/' - operator or the `$' operator). The start condition, `^', and - `<<EOF>>' patterns can only occur at the beginning of a pattern, - and, as well as with `/' and `$', cannot be grouped inside - parentheses. A `^' which does not occur at the beginning of a - rule or a `$' which does not occur at the end of a rule loses its + operation, as in, '[[:alpha:]]{-}[[:lower:]]{+}[q]', which is + equivalent to '[A-Zq]' in the "C" locale. + + * A rule can have at most one instance of trailing context (the '/' + operator or the '$' operator). The start condition, '^', and + '<<EOF>>' patterns can only occur at the beginning of a pattern, + and, as well as with '/' and '$', cannot be grouped inside + parentheses. A '^' which does not occur at the beginning of a rule + or a '$' which does not occur at the end of a rule loses its special properties and is treated as a normal character. * The following are invalid: @@ -889,23 +889,23 @@ not be desirable. foo/bar$ <sc1>foo<sc2>bar - Note that the first of these can be written `foo/bar\n'. + Note that the first of these can be written 'foo/bar\n'. - * The following will result in `$' or `^' being treated as a normal + * The following will result in '$' or '^' being treated as a normal character: foo|(bar$) foo|^bar - If the desired meaning is a `foo' or a - `bar'-followed-by-a-newline, the following could be used (the - special `|' action is explained below, *note Actions::): + If the desired meaning is a 'foo' or a 'bar'-followed-by-a-newline, + the following could be used (the special '|' action is explained + below, *note Actions::): foo | bar$ /* action goes here */ - A similar trick will work for matching a `foo' or a - `bar'-at-the-beginning-of-a-line. + A similar trick will work for matching a 'foo' or a + 'bar'-at-the-beginning-of-a-line. File: flex.info, Node: Matching, Next: Actions, Prev: Patterns, Up: Top @@ -918,61 +918,61 @@ strings which match any of its patterns. If it finds more than one match, it takes the one matching the most text (for trailing context rules, this includes the length of the trailing part, even though it will then be returned to the input). If it finds two or more matches of -the same length, the rule listed first in the `flex' input file is +the same length, the rule listed first in the 'flex' input file is chosen. Once the match is determined, the text corresponding to the match (called the "token") is made available in the global character pointer -`yytext', and its length in the global integer `yyleng'. The "action" -corresponding to the matched pattern is then executed (*note -Actions::), and then the remaining input is scanned for another match. +'yytext', and its length in the global integer 'yyleng'. The "action" +corresponding to the matched pattern is then executed (*note Actions::), +and then the remaining input is scanned for another match. If no match is found, then the "default rule" is executed: the next character in the input is considered matched and copied to the standard -output. Thus, the simplest valid `flex' input is: +output. Thus, the simplest valid 'flex' input is: %% - which generates a scanner that simply copies its input (one -character at a time) to its output. + which generates a scanner that simply copies its input (one character +at a time) to its output. - Note that `yytext' can be defined in two different ways: either as a -character _pointer_ or as a character _array_. You can control which -definition `flex' uses by including one of the special directives -`%pointer' or `%array' in the first (definitions) section of your flex -input. The default is `%pointer', unless you use the `-l' lex -compatibility option, in which case `yytext' will be an array. The -advantage of using `%pointer' is substantially faster scanning and no + Note that 'yytext' can be defined in two different ways: either as a +character _pointer_ or as a character _array_. You can control which +definition 'flex' uses by including one of the special directives +'%pointer' or '%array' in the first (definitions) section of your flex +input. The default is '%pointer', unless you use the '-l' lex +compatibility option, in which case 'yytext' will be an array. The +advantage of using '%pointer' is substantially faster scanning and no buffer overflow when matching very large tokens (unless you run out of dynamic memory). The disadvantage is that you are restricted in how -your actions can modify `yytext' (*note Actions::), and calls to the -`unput()' function destroys the present contents of `yytext', which can -be a considerable porting headache when moving between different `lex' +your actions can modify 'yytext' (*note Actions::), and calls to the +'unput()' function destroys the present contents of 'yytext', which can +be a considerable porting headache when moving between different 'lex' versions. - The advantage of `%array' is that you can then modify `yytext' to -your heart's content, and calls to `unput()' do not destroy `yytext' -(*note Actions::). Furthermore, existing `lex' programs sometimes -access `yytext' externally using declarations of the form: + The advantage of '%array' is that you can then modify 'yytext' to +your heart's content, and calls to 'unput()' do not destroy 'yytext' +(*note Actions::). Furthermore, existing 'lex' programs sometimes +access 'yytext' externally using declarations of the form: extern char yytext[]; - This definition is erroneous when used with `%pointer', but correct -for `%array'. + This definition is erroneous when used with '%pointer', but correct +for '%array'. - The `%array' declaration defines `yytext' to be an array of `YYLMAX' + The '%array' declaration defines 'yytext' to be an array of 'YYLMAX' characters, which defaults to a fairly large value. You can change the -size by simply #define'ing `YYLMAX' to a different value in the first -section of your `flex' input. As mentioned above, with `%pointer' +size by simply #define'ing 'YYLMAX' to a different value in the first +section of your 'flex' input. As mentioned above, with '%pointer' yytext grows dynamically to accommodate large tokens. While this means -your `%pointer' scanner can accommodate very large tokens (such as +your '%pointer' scanner can accommodate very large tokens (such as matching entire blocks of comments), bear in mind that each time the -scanner must resize `yytext' it also must rescan the entire token from -the beginning, so matching such tokens can prove slow. `yytext' -presently does _not_ dynamically grow if a call to `unput()' results in +scanner must resize 'yytext' it also must rescan the entire token from +the beginning, so matching such tokens can prove slow. 'yytext' +presently does _not_ dynamically grow if a call to 'unput()' results in too much text being pushed back; instead, a run-time error results. - Also note that you cannot use `%array' with C++ scanner classes + Also note that you cannot use '%array' with C++ scanner classes (*note Cxx::). @@ -986,7 +986,7 @@ arbitrary C statement. The pattern ends at the first non-escaped whitespace character; the remainder of the line is its action. If the action is empty, then when the pattern is matched the input token is simply discarded. For example, here is the specification for a program -which deletes all occurrences of `zap me' from its input: +which deletes all occurrences of 'zap me' from its input: %% "zap me" @@ -1001,50 +1001,49 @@ single blank, and throws away whitespace found at the end of a line: [ \t]+ putchar( ' ' ); [ \t]+$ /* ignore this token */ - If the action contains a `{', then the action spans till the -balancing `}' is found, and the action may cross multiple lines. -`flex' knows about C strings and comments and won't be fooled by braces -found within them, but also allows actions to begin with `%{' and will -consider the action to be all the text up to the next `%}' (regardless + If the action contains a '{', then the action spans till the +balancing '}' is found, and the action may cross multiple lines. 'flex' +knows about C strings and comments and won't be fooled by braces found +within them, but also allows actions to begin with '%{' and will +consider the action to be all the text up to the next '%}' (regardless of ordinary braces inside the action). - An action consisting solely of a vertical bar (`|') means "same as + An action consisting solely of a vertical bar ('|') means "same as the action for the next rule". See below for an illustration. - Actions can include arbitrary C code, including `return' statements -to return a value to whatever routine called `yylex()'. Each time -`yylex()' is called it continues processing tokens from where it last + Actions can include arbitrary C code, including 'return' statements +to return a value to whatever routine called 'yylex()'. Each time +'yylex()' is called it continues processing tokens from where it last left off until it either reaches the end of the file or executes a return. - Actions are free to modify `yytext' except for lengthening it -(adding characters to its end-these will overwrite later characters in -the input stream). This however does not apply when using `%array' -(*note Matching::). In that case, `yytext' may be freely modified in -any way. + Actions are free to modify 'yytext' except for lengthening it (adding +characters to its end-these will overwrite later characters in the input +stream). This however does not apply when using '%array' (*note +Matching::). In that case, 'yytext' may be freely modified in any way. - Actions are free to modify `yyleng' except they should not do so if -the action also includes use of `yymore()' (see below). + Actions are free to modify 'yyleng' except they should not do so if +the action also includes use of 'yymore()' (see below). - There are a number of special directives which can be included -within an action: + There are a number of special directives which can be included within +an action: -`ECHO' +'ECHO' copies yytext to the scanner's output. -`BEGIN' +'BEGIN' followed by the name of a start condition places the scanner in the corresponding start condition (see below). -`REJECT' +'REJECT' directs the scanner to proceed on to the "second best" rule which matched the input (or a prefix of the input). The rule is chosen - as described above in *note Matching::, and `yytext' and `yyleng' + as described above in *note Matching::, and 'yytext' and 'yyleng' set up appropriately. It may either be one which matched as much - text as the originally chosen rule but came later in the `flex' + text as the originally chosen rule but came later in the 'flex' input file, or one which matched less text. For example, the following will both count the words in the input and call the - routine `special()' whenever `frob' is seen: + routine 'special()' whenever 'frob' is seen: int word_count = 0; %% @@ -1052,12 +1051,12 @@ within an action: frob special(); REJECT; [^ \t\n]+ ++word_count; - Without the `REJECT', any occurrences of `frob' in the input would + Without the 'REJECT', any occurrences of 'frob' in the input would not be counted as words, since the scanner normally executes only - one action per token. Multiple uses of `REJECT' are allowed, each + one action per token. Multiple uses of 'REJECT' are allowed, each one finding the next best choice to the currently active rule. For - example, when the following scanner scans the token `abcd', it will - write `abcdabcaba' to the output: + example, when the following scanner scans the token 'abcd', it will + write 'abcdabcaba' to the output: %% a | @@ -1067,59 +1066,59 @@ within an action: .|\n /* eat up any unmatched character */ The first three rules share the fourth's action since they use the - special `|' action. + special '|' action. - `REJECT' is a particularly expensive feature in terms of scanner + 'REJECT' is a particularly expensive feature in terms of scanner performance; if it is used in _any_ of the scanner's actions it will slow down _all_ of the scanner's matching. Furthermore, - `REJECT' cannot be used with the `-Cf' or `-CF' options (*note + 'REJECT' cannot be used with the '-Cf' or '-CF' options (*note Scanner Options::). - Note also that unlike the other special actions, `REJECT' is a + Note also that unlike the other special actions, 'REJECT' is a _branch_. Code immediately following it in the action will _not_ be executed. -`yymore()' +'yymore()' tells the scanner that the next time it matches a rule, the corresponding token should be _appended_ onto the current value of - `yytext' rather than replacing it. For example, given the input - `mega-kludge' the following will write `mega-mega-kludge' to the + 'yytext' rather than replacing it. For example, given the input + 'mega-kludge' the following will write 'mega-mega-kludge' to the output: %% mega- ECHO; yymore(); kludge ECHO; - First `mega-' is matched and echoed to the output. Then `kludge' - is matched, but the previous `mega-' is still hanging around at the - beginning of `yytext' so the `ECHO' for the `kludge' rule will - actually write `mega-kludge'. + First 'mega-' is matched and echoed to the output. Then 'kludge' + is matched, but the previous 'mega-' is still hanging around at the + beginning of 'yytext' so the 'ECHO' for the 'kludge' rule will + actually write 'mega-kludge'. - Two notes regarding use of `yymore()'. First, `yymore()' depends on -the value of `yyleng' correctly reflecting the size of the current -token, so you must not modify `yyleng' if you are using `yymore()'. -Second, the presence of `yymore()' in the scanner's action entails a + Two notes regarding use of 'yymore()'. First, 'yymore()' depends on +the value of 'yyleng' correctly reflecting the size of the current +token, so you must not modify 'yyleng' if you are using 'yymore()'. +Second, the presence of 'yymore()' in the scanner's action entails a minor performance penalty in the scanner's matching speed. - `yyless(n)' returns all but the first `n' characters of the current + 'yyless(n)' returns all but the first 'n' characters of the current token back to the input stream, where they will be rescanned when the -scanner looks for the next match. `yytext' and `yyleng' are adjusted -appropriately (e.g., `yyleng' will now be equal to `n'). For example, -on the input `foobar' the following will write out `foobarbar': +scanner looks for the next match. 'yytext' and 'yyleng' are adjusted +appropriately (e.g., 'yyleng' will now be equal to 'n'). For example, +on the input 'foobar' the following will write out 'foobarbar': %% foobar ECHO; yyless(3); [a-z]+ ECHO; - An argument of 0 to `yyless()' will cause the entire current input + An argument of 0 to 'yyless()' will cause the entire current input string to be scanned again. Unless you've changed how the scanner will -subsequently process its input (using `BEGIN', for example), this will +subsequently process its input (using 'BEGIN', for example), this will result in an endless loop. - Note that `yyless()' is a macro and can only be used in the flex + Note that 'yyless()' is a macro and can only be used in the flex input file, not from other source files. - `unput(c)' puts the character `c' back onto the input stream. It + 'unput(c)' puts the character 'c' back onto the input stream. It will be the next character scanned. The following action will take the current token and cause it to be rescanned enclosed in parentheses. @@ -1134,27 +1133,27 @@ current token and cause it to be rescanned enclosed in parentheses. free( yycopy ); } - Note that since each `unput()' puts the given character back at the + Note that since each 'unput()' puts the given character back at the _beginning_ of the input stream, pushing back strings must be done back-to-front. - An important potential problem when using `unput()' is that if you -are using `%pointer' (the default), a call to `unput()' _destroys_ the -contents of `yytext', starting with its rightmost character and + An important potential problem when using 'unput()' is that if you +are using '%pointer' (the default), a call to 'unput()' _destroys_ the +contents of 'yytext', starting with its rightmost character and devouring one character to the left with each call. If you need the -value of `yytext' preserved after a call to `unput()' (as in the above -example), you must either first copy it elsewhere, or build your -scanner using `%array' instead (*note Matching::). +value of 'yytext' preserved after a call to 'unput()' (as in the above +example), you must either first copy it elsewhere, or build your scanner +using '%array' instead (*note Matching::). - Finally, note that you cannot put back `EOF' to attempt to mark the + Finally, note that you cannot put back 'EOF' to attempt to mark the input stream with an end-of-file. - `input()' reads the next character from the input stream. For + 'input()' reads the next character from the input stream. For example, the following is one way to eat up C comments: %% "/*" { - register int c; + int c; for ( ; ; ) { @@ -1178,19 +1177,19 @@ example, the following is one way to eat up C comments: } } - (Note that if the scanner is compiled using `C++', then `input()' is + (Note that if the scanner is compiled using 'C++', then 'input()' is instead referred to as yyinput(), in order to avoid a name clash with -the `C++' stream by the name of `input'.) +the 'C++' stream by the name of 'input'.) - `YY_FLUSH_BUFFER;' flushes the scanner's internal buffer so that the + 'YY_FLUSH_BUFFER;' flushes the scanner's internal buffer so that the next time the scanner attempts to match a token, it will first refill -the buffer using `YY_INPUT()' (*note Generated Scanner::). This action -is a special case of the more general `yy_flush_buffer;' function, +the buffer using 'YY_INPUT()' (*note Generated Scanner::). This action +is a special case of the more general 'yy_flush_buffer;' function, described below (*note Multiple Input Buffers::) - `yyterminate()' can be used in lieu of a return statement in an + 'yyterminate()' can be used in lieu of a return statement in an action. It terminates the scanner and returns a 0 to the scanner's -caller, indicating "all done". By default, `yyterminate()' is also +caller, indicating "all done". By default, 'yyterminate()' is also called when an end-of-file is encountered. It is a macro and may be redefined. @@ -1200,10 +1199,10 @@ File: flex.info, Node: Generated Scanner, Next: Start Conditions, Prev: Actio 9 The Generated Scanner *********************** -The output of `flex' is the file `lex.yy.c', which contains the -scanning routine `yylex()', a number of tables used by it for matching -tokens, and a number of auxiliary routines and macros. By default, -`yylex()' is declared as follows: +The output of 'flex' is the file 'lex.yy.c', which contains the scanning +routine 'yylex()', a number of tables used by it for matching tokens, +and a number of auxiliary routines and macros. By default, 'yylex()' is +declared as follows: int yylex() { @@ -1211,62 +1210,62 @@ tokens, and a number of auxiliary routines and macros. By default, } (If your environment supports function prototypes, then it will be -`int yylex( void )'.) This definition may be changed by defining the -`YY_DECL' macro. For example, you could use: +'int yylex( void )'.) This definition may be changed by defining the +'YY_DECL' macro. For example, you could use: #define YY_DECL float lexscan( a, b ) float a, b; - to give the scanning routine the name `lexscan', returning a float, + to give the scanning routine the name 'lexscan', returning a float, and taking two floats as arguments. Note that if you give arguments to the scanning routine using a K&R-style/non-prototyped function declaration, you must terminate the definition with a semi-colon (;). - `flex' generates `C99' function definitions by default. However flex -does have the ability to generate obsolete, er, `traditional', function -definitions. This is to support bootstrapping gcc on old systems. + 'flex' generates 'C99' function definitions by default. However flex +does have the ability to generate obsolete, er, 'traditional', function +definitions. This is to support bootstrapping gcc on old systems. Unfortunately, traditional definitions prevent us from using any standard data types smaller than int (such as short, char, or bool) as -function arguments. For this reason, future versions of `flex' may +function arguments. For this reason, future versions of 'flex' may generate standard C99 code only, leaving K&R-style functions to the -historians. Currently, if you do *not* want `C99' definitions, then -you must use `%option noansi-definitions'. +historians. Currently, if you do *not* want 'C99' definitions, then you +must use '%option noansi-definitions'. - Whenever `yylex()' is called, it scans tokens from the global input -file `yyin' (which defaults to stdin). It continues until it either -reaches an end-of-file (at which point it returns the value 0) or one -of its actions executes a `return' statement. + Whenever 'yylex()' is called, it scans tokens from the global input +file 'yyin' (which defaults to stdin). It continues until it either +reaches an end-of-file (at which point it returns the value 0) or one of +its actions executes a 'return' statement. If the scanner reaches an end-of-file, subsequent calls are undefined -unless either `yyin' is pointed at a new input file (in which case -scanning continues from that file), or `yyrestart()' is called. -`yyrestart()' takes one argument, a `FILE *' pointer (which can be -NULL, if you've set up `YY_INPUT' to scan from a source other than -`yyin'), and initializes `yyin' for scanning from that file. -Essentially there is no difference between just assigning `yyin' to a -new input file or using `yyrestart()' to do so; the latter is available -for compatibility with previous versions of `flex', and because it can -be used to switch input files in the middle of scanning. It can also -be used to throw away the current input buffer, by calling it with an -argument of `yyin'; but it would be better to use `YY_FLUSH_BUFFER' -(*note Actions::). Note that `yyrestart()' does _not_ reset the start -condition to `INITIAL' (*note Start Conditions::). - - If `yylex()' stops scanning due to executing a `return' statement in +unless either 'yyin' is pointed at a new input file (in which case +scanning continues from that file), or 'yyrestart()' is called. +'yyrestart()' takes one argument, a 'FILE *' pointer (which can be NULL, +if you've set up 'YY_INPUT' to scan from a source other than 'yyin'), +and initializes 'yyin' for scanning from that file. Essentially there +is no difference between just assigning 'yyin' to a new input file or +using 'yyrestart()' to do so; the latter is available for compatibility +with previous versions of 'flex', and because it can be used to switch +input files in the middle of scanning. It can also be used to throw +away the current input buffer, by calling it with an argument of 'yyin'; +but it would be better to use 'YY_FLUSH_BUFFER' (*note Actions::). Note +that 'yyrestart()' does _not_ reset the start condition to 'INITIAL' +(*note Start Conditions::). + + If 'yylex()' stops scanning due to executing a 'return' statement in one of the actions, the scanner may then be called again and it will resume scanning where it left off. By default (and for purposes of efficiency), the scanner uses -block-reads rather than simple `getc()' calls to read characters from -`yyin'. The nature of how it gets its input can be controlled by -defining the `YY_INPUT' macro. The calling sequence for `YY_INPUT()' -is `YY_INPUT(buf,result,max_size)'. Its action is to place up to -`max_size' characters in the character array `buf' and return in the -integer variable `result' either the number of characters read or the -constant `YY_NULL' (0 on Unix systems) to indicate `EOF'. The default -`YY_INPUT' reads from the global file-pointer `yyin'. - - Here is a sample definition of `YY_INPUT' (in the definitions -section of the input file): +block-reads rather than simple 'getc()' calls to read characters from +'yyin'. The nature of how it gets its input can be controlled by +defining the 'YY_INPUT' macro. The calling sequence for 'YY_INPUT()' is +'YY_INPUT(buf,result,max_size)'. Its action is to place up to +'max_size' characters in the character array 'buf' and return in the +integer variable 'result' either the number of characters read or the +constant 'YY_NULL' (0 on Unix systems) to indicate 'EOF'. The default +'YY_INPUT' reads from the global file-pointer 'yyin'. + + Here is a sample definition of 'YY_INPUT' (in the definitions section +of the input file): %{ #define YY_INPUT(buf,result,max_size) \ @@ -1280,24 +1279,24 @@ section of the input file): character at a time. When the scanner receives an end-of-file indication from YY_INPUT, it -then checks the `yywrap()' function. If `yywrap()' returns false +then checks the 'yywrap()' function. If 'yywrap()' returns false (zero), then it is assumed that the function has gone ahead and set up -`yyin' to point to another input file, and scanning continues. If it -returns true (non-zero), then the scanner terminates, returning 0 to -its caller. Note that in either case, the start condition remains -unchanged; it does _not_ revert to `INITIAL'. - - If you do not supply your own version of `yywrap()', then you must -either use `%option noyywrap' (in which case the scanner behaves as -though `yywrap()' returned 1), or you must link with `-lfl' to obtain +'yyin' to point to another input file, and scanning continues. If it +returns true (non-zero), then the scanner terminates, returning 0 to its +caller. Note that in either case, the start condition remains +unchanged; it does _not_ revert to 'INITIAL'. + + If you do not supply your own version of 'yywrap()', then you must +either use '%option noyywrap' (in which case the scanner behaves as +though 'yywrap()' returned 1), or you must link with '-lfl' to obtain the default version of the routine, which always returns 1. For scanning from in-memory buffers (e.g., scanning strings), see -*note Scanning Strings::. *Note Multiple Input Buffers::. +*note Scanning Strings::. *Note Multiple Input Buffers::. - The scanner writes its `ECHO' output to the `yyout' global (default, -`stdout'), which may be redefined by the user simply by assigning it to -some other `FILE' pointer. + The scanner writes its 'ECHO' output to the 'yyout' global (default, +'stdout'), which may be redefined by the user simply by assigning it to +some other 'FILE' pointer. File: flex.info, Node: Start Conditions, Next: Multiple Input Buffers, Prev: Generated Scanner, Up: Top @@ -1305,15 +1304,15 @@ File: flex.info, Node: Start Conditions, Next: Multiple Input Buffers, Prev: 10 Start Conditions ******************* -`flex' provides a mechanism for conditionally activating rules. Any -rule whose pattern is prefixed with `<sc>' will only be active when the -scanner is in the "start condition" named `sc'. For example, +'flex' provides a mechanism for conditionally activating rules. Any +rule whose pattern is prefixed with '<sc>' will only be active when the +scanner is in the "start condition" named 'sc'. For example, <STRING>[^"]* { /* eat up the string body ... */ ... } - will be active only when the scanner is in the `STRING' start + will be active only when the scanner is in the 'STRING' start condition, and <INITIAL,STRING,QUOTE>\. { /* handle an escape ... */ @@ -1321,23 +1320,23 @@ condition, and } will be active only when the current start condition is either -`INITIAL', `STRING', or `QUOTE'. +'INITIAL', 'STRING', or 'QUOTE'. Start conditions are declared in the definitions (first) section of -the input using unindented lines beginning with either `%s' or `%x' +the input using unindented lines beginning with either '%s' or '%x' followed by a list of names. The former declares "inclusive" start conditions, the latter "exclusive" start conditions. A start condition -is activated using the `BEGIN' action. Until the next `BEGIN' action -is executed, rules with the given start condition will be active and -rules with other start conditions will be inactive. If the start -condition is inclusive, then rules with no start conditions at all will -also be active. If it is exclusive, then _only_ rules qualified with -the start condition will be active. A set of rules contingent on the -same exclusive start condition describe a scanner which is independent -of any of the other rules in the `flex' input. Because of this, -exclusive start conditions make it easy to specify "mini-scanners" -which scan portions of the input that are syntactically different from -the rest (e.g., comments). +is activated using the 'BEGIN' action. Until the next 'BEGIN' action is +executed, rules with the given start condition will be active and rules +with other start conditions will be inactive. If the start condition is +inclusive, then rules with no start conditions at all will also be +active. If it is exclusive, then _only_ rules qualified with the start +condition will be active. A set of rules contingent on the same +exclusive start condition describe a scanner which is independent of any +of the other rules in the 'flex' input. Because of this, exclusive +start conditions make it easy to specify "mini-scanners" which scan +portions of the input that are syntactically different from the rest +(e.g., comments). If the distinction between inclusive and exclusive start conditions is still a little vague, here's a simple example illustrating the @@ -1359,15 +1358,15 @@ connection between the two. The set of rules: <INITIAL,example>bar something_else(); - Without the `<INITIAL,example>' qualifier, the `bar' pattern in the + Without the '<INITIAL,example>' qualifier, the 'bar' pattern in the second example wouldn't be active (i.e., couldn't match) when in start -condition `example'. If we just used `<example>' to qualify `bar', -though, then it would only be active in `example' and not in `INITIAL', +condition 'example'. If we just used '<example>' to qualify 'bar', +though, then it would only be active in 'example' and not in 'INITIAL', while in the first example it's active in both, because in the first -example the `example' start condition is an inclusive `(%s)' start +example the 'example' start condition is an inclusive '(%s)' start condition. - Also note that the special start-condition specifier `<*>' matches + Also note that the special start-condition specifier '<*>' matches every start condition. Thus, the above example could also have been written: @@ -1378,21 +1377,21 @@ written: <*>bar something_else(); - The default rule (to `ECHO' any unmatched character) remains active + The default rule (to 'ECHO' any unmatched character) remains active in start conditions. It is equivalent to: <*>.|\n ECHO; - `BEGIN(0)' returns to the original state where only the rules with -no start conditions are active. This state can also be referred to as -the start-condition `INITIAL', so `BEGIN(INITIAL)' is equivalent to -`BEGIN(0)'. (The parentheses around the start condition name are not + 'BEGIN(0)' returns to the original state where only the rules with no +start conditions are active. This state can also be referred to as the +start-condition 'INITIAL', so 'BEGIN(INITIAL)' is equivalent to +'BEGIN(0)'. (The parentheses around the start condition name are not required but are considered good style.) - `BEGIN' actions can also be given as indented code at the beginning + 'BEGIN' actions can also be given as indented code at the beginning of the rules section. For example, the following will cause the scanner -to enter the `SPECIAL' start condition whenever `yylex()' is called and -the global variable `enter_special' is true: +to enter the 'SPECIAL' start condition whenever 'yylex()' is called and +the global variable 'enter_special' is true: int enter_special; @@ -1405,11 +1404,11 @@ the global variable `enter_special' is true: ...more rules follow... To illustrate the uses of start conditions, here is a scanner which -provides two different interpretations of a string like `123.456'. By -default it will treat it as three tokens, the integer `123', a dot -(`.'), and the integer `456'. But if the string is preceded earlier in -the line by the string `expect-floats' it will treat it as a single -token, the floating-point number `123.456': +provides two different interpretations of a string like '123.456'. By +default it will treat it as three tokens, the integer '123', a dot +('.'), and the integer '456'. But if the string is preceded earlier in +the line by the string 'expect-floats' it will treat it as a single +token, the floating-point number '123.456': %{ #include <math.h> @@ -1455,11 +1454,11 @@ maintaining a count of the current input line. This scanner goes to a bit of trouble to match as much text as possible with each rule. In general, when attempting to write a -high-speed scanner try to match as much possible in each rule, as it's -a big win. +high-speed scanner try to match as much possible in each rule, as it's a +big win. - Note that start-conditions names are really integer values and can -be stored as such. Thus, the above could be extended in the following + Note that start-conditions names are really integer values and can be +stored as such. Thus, the above could be extended in the following fashion: %x comment foo @@ -1485,18 +1484,18 @@ fashion: <comment>"*"+"/" BEGIN(comment_caller); Furthermore, you can access the current start condition using the -integer-valued `YY_START' macro. For example, the above assignments to -`comment_caller' could instead be written +integer-valued 'YY_START' macro. For example, the above assignments to +'comment_caller' could instead be written comment_caller = YY_START; - Flex provides `YYSTATE' as an alias for `YY_START' (since that is -what's used by AT&T `lex'). + Flex provides 'YYSTATE' as an alias for 'YY_START' (since that is +what's used by AT&T 'lex'). For historical reasons, start conditions do not have their own -name-space within the generated scanner. The start condition names are +name-space within the generated scanner. The start condition names are unmodified in the generated scanner and generated header. *Note -option-header::. *Note option-prefix::. +option-header::. *Note option-prefix::. Finally, here's an example of how to match C-style quoted strings using exclusive start conditions, including expanded escape sequences @@ -1564,9 +1563,9 @@ condition "scope". A start condition scope is begun with: <SCs>{ - where `SCs' is a list of one or more start conditions. Inside the -start condition scope, every rule automatically has the prefix `SCs>' -applied to it, until a `}' which matches the initial `{'. So, for + where '<SCs>' is a list of one or more start conditions. Inside the +start condition scope, every rule automatically has the prefix '<SCs>' +applied to it, until a '}' which matches the initial '{'. So, for example, <ESC>{ @@ -1585,17 +1584,17 @@ example, Start condition scopes may be nested. - The following routines are available for manipulating stacks of -start conditions: + The following routines are available for manipulating stacks of start +conditions: - -- Function: void yy_push_state ( int `new_state' ) + -- Function: void yy_push_state ( int 'new_state' ) pushes the current start condition onto the top of the start - condition stack and switches to `new_state' as though you had used - `BEGIN new_state' (recall that start condition names are also + condition stack and switches to 'new_state' as though you had used + 'BEGIN new_state' (recall that start condition names are also integers). -- Function: void yy_pop_state () - pops the top of the stack and switches to it via `BEGIN'. + pops the top of the stack and switches to it via 'BEGIN'. -- Function: int yy_top_state () returns the top of the stack without altering the stack's contents. @@ -1603,7 +1602,7 @@ start conditions: The start condition stack grows dynamically and so has no built-in size limitation. If memory is exhausted, program execution aborts. - To use start condition stacks, your scanner must include a `%option + To use start condition stacks, your scanner must include a '%option stack' directive (*note Scanner Options::). @@ -1613,82 +1612,82 @@ File: flex.info, Node: Multiple Input Buffers, Next: EOF, Prev: Start Conditi ************************* Some scanners (such as those which support "include" files) require -reading from several input streams. As `flex' scanners do a large +reading from several input streams. As 'flex' scanners do a large amount of buffering, one cannot control where the next input will be -read from by simply writing a `YY_INPUT()' which is sensitive to the -scanning context. `YY_INPUT()' is only called when the scanner reaches +read from by simply writing a 'YY_INPUT()' which is sensitive to the +scanning context. 'YY_INPUT()' is only called when the scanner reaches the end of its buffer, which may be a long time after scanning a -statement such as an `include' statement which requires switching the +statement such as an 'include' statement which requires switching the input source. - To negotiate these sorts of problems, `flex' provides a mechanism -for creating and switching between multiple input buffers. An input -buffer is created by using: + To negotiate these sorts of problems, 'flex' provides a mechanism for +creating and switching between multiple input buffers. An input buffer +is created by using: -- Function: YY_BUFFER_STATE yy_create_buffer ( FILE *file, int size ) - which takes a `FILE' pointer and a size and creates a buffer -associated with the given file and large enough to hold `size' -characters (when in doubt, use `YY_BUF_SIZE' for the size). It returns -a `YY_BUFFER_STATE' handle, which may then be passed to other routines -(see below). The `YY_BUFFER_STATE' type is a pointer to an opaque -`struct yy_buffer_state' structure, so you may safely initialize -`YY_BUFFER_STATE' variables to `((YY_BUFFER_STATE) 0)' if you wish, and + which takes a 'FILE' pointer and a size and creates a buffer +associated with the given file and large enough to hold 'size' +characters (when in doubt, use 'YY_BUF_SIZE' for the size). It returns +a 'YY_BUFFER_STATE' handle, which may then be passed to other routines +(see below). The 'YY_BUFFER_STATE' type is a pointer to an opaque +'struct yy_buffer_state' structure, so you may safely initialize +'YY_BUFFER_STATE' variables to '((YY_BUFFER_STATE) 0)' if you wish, and also refer to the opaque structure in order to correctly declare input buffers in source files other than that of your scanner. Note that the -`FILE' pointer in the call to `yy_create_buffer' is only used as the -value of `yyin' seen by `YY_INPUT'. If you redefine `YY_INPUT()' so it -no longer uses `yyin', then you can safely pass a NULL `FILE' pointer to -`yy_create_buffer'. You select a particular buffer to scan from using: +'FILE' pointer in the call to 'yy_create_buffer' is only used as the +value of 'yyin' seen by 'YY_INPUT'. If you redefine 'YY_INPUT()' so it +no longer uses 'yyin', then you can safely pass a NULL 'FILE' pointer to +'yy_create_buffer'. You select a particular buffer to scan from using: -- Function: void yy_switch_to_buffer ( YY_BUFFER_STATE new_buffer ) The above function switches the scanner's input buffer so subsequent -tokens will come from `new_buffer'. Note that `yy_switch_to_buffer()' -may be used by `yywrap()' to set things up for continued scanning, -instead of opening a new file and pointing `yyin' at it. If you are +tokens will come from 'new_buffer'. Note that 'yy_switch_to_buffer()' +may be used by 'yywrap()' to set things up for continued scanning, +instead of opening a new file and pointing 'yyin' at it. If you are looking for a stack of input buffers, then you want to use -`yypush_buffer_state()' instead of this function. Note also that -switching input sources via either `yy_switch_to_buffer()' or -`yywrap()' does _not_ change the start condition. +'yypush_buffer_state()' instead of this function. Note also that +switching input sources via either 'yy_switch_to_buffer()' or 'yywrap()' +does _not_ change the start condition. -- Function: void yy_delete_buffer ( YY_BUFFER_STATE buffer ) - is used to reclaim the storage associated with a buffer. (`buffer' + is used to reclaim the storage associated with a buffer. ('buffer' can be NULL, in which case the routine does nothing.) You can also clear the current contents of a buffer using: -- Function: void yypush_buffer_state ( YY_BUFFER_STATE buffer ) This function pushes the new buffer state onto an internal stack. -The pushed state becomes the new current state. The stack is maintained -by flex and will grow as required. This function is intended to be used -instead of `yy_switch_to_buffer', when you want to change states, but +The pushed state becomes the new current state. The stack is maintained +by flex and will grow as required. This function is intended to be used +instead of 'yy_switch_to_buffer', when you want to change states, but preserve the current state for later use. -- Function: void yypop_buffer_state ( ) This function removes the current state from the top of the stack, -and deletes it by calling `yy_delete_buffer'. The next state on the +and deletes it by calling 'yy_delete_buffer'. The next state on the stack, if any, becomes the new current state. -- Function: void yy_flush_buffer ( YY_BUFFER_STATE buffer ) This function discards the buffer's contents, so the next time the scanner attempts to match a token from the buffer, it will first fill -the buffer anew using `YY_INPUT()'. +the buffer anew using 'YY_INPUT()'. -- Function: YY_BUFFER_STATE yy_new_buffer ( FILE *file, int size ) - is an alias for `yy_create_buffer()', provided for compatibility -with the C++ use of `new' and `delete' for creating and destroying -dynamic objects. + is an alias for 'yy_create_buffer()', provided for compatibility with +the C++ use of 'new' and 'delete' for creating and destroying dynamic +objects. - `YY_CURRENT_BUFFER' macro returns a `YY_BUFFER_STATE' handle to the -current buffer. It should not be used as an lvalue. + 'YY_CURRENT_BUFFER' macro returns a 'YY_BUFFER_STATE' handle to the +current buffer. It should not be used as an lvalue. Here are two examples of using these features for writing a scanner -which expands include files (the `<<EOF>>' feature is discussed below). +which expands include files (the '<<EOF>>' feature is discussed below). This first example uses yypush_buffer_state and yypop_buffer_state. Flex maintains the stack internally. @@ -1725,8 +1724,8 @@ Flex maintains the stack internally. } The second example, below, does the same thing as the previous -example did, but manages its own input buffer stack manually (instead -of letting flex do it). +example did, but manages its own input buffer stack manually (instead of +letting flex do it). /* the "incl" state is used for picking up the name * of an include file @@ -1784,34 +1783,34 @@ of letting flex do it). The following routines are available for setting up input buffers for scanning in-memory strings instead of files. All of them create a new input buffer for scanning the string, and return a corresponding -`YY_BUFFER_STATE' handle (which you should delete with -`yy_delete_buffer()' when done with it). They also switch to the new -buffer using `yy_switch_to_buffer()', so the next call to `yylex()' -will start scanning the string. +'YY_BUFFER_STATE' handle (which you should delete with +'yy_delete_buffer()' when done with it). They also switch to the new +buffer using 'yy_switch_to_buffer()', so the next call to 'yylex()' will +start scanning the string. -- Function: YY_BUFFER_STATE yy_scan_string ( const char *str ) scans a NUL-terminated string. - -- Function: YY_BUFFER_STATE yy_scan_bytes ( const char *bytes, int - len ) - scans `len' bytes (including possibly `NUL's) starting at location - `bytes'. + -- Function: YY_BUFFER_STATE yy_scan_bytes ( const char *bytes, int len + ) + scans 'len' bytes (including possibly 'NUL's) starting at location + 'bytes'. Note that both of these functions create and scan a _copy_ of the -string or bytes. (This may be desirable, since `yylex()' modifies the +string or bytes. (This may be desirable, since 'yylex()' modifies the contents of the buffer it is scanning.) You can avoid the copy by using: -- Function: YY_BUFFER_STATE yy_scan_buffer (char *base, yy_size_t size) - which scans in place the buffer starting at `base', consisting of - `size' bytes, the last two bytes of which _must_ be - `YY_END_OF_BUFFER_CHAR' (ASCII NUL). These last two bytes are not - scanned; thus, scanning consists of `base[0]' through - `base[size-2]', inclusive. - - If you fail to set up `base' in this manner (i.e., forget the final -two `YY_END_OF_BUFFER_CHAR' bytes), then `yy_scan_buffer()' returns a + which scans in place the buffer starting at 'base', consisting of + 'size' bytes, the last two bytes of which _must_ be + 'YY_END_OF_BUFFER_CHAR' (ASCII NUL). These last two bytes are not + scanned; thus, scanning consists of 'base[0]' through + 'base[size-2]', inclusive. + + If you fail to set up 'base' in this manner (i.e., forget the final +two 'YY_END_OF_BUFFER_CHAR' bytes), then 'yy_scan_buffer()' returns a NULL pointer instead of creating a new input buffer. -- Data type: yy_size_t @@ -1824,27 +1823,27 @@ File: flex.info, Node: EOF, Next: Misc Macros, Prev: Multiple Input Buffers, 12 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). The action must finish by -doing one of the following things: +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). The action must finish by doing +one of the following things: - * assigning `yyin' to a new input file (in previous versions of - `flex', after doing the assignment you had to call the special - action `YY_NEW_FILE'. This is no longer necessary.) + * assigning 'yyin' to a new input file (in previous versions of + 'flex', after doing the assignment you had to call the special + action 'YY_NEW_FILE'. This is no longer necessary.) - * executing a `return' statement; + * executing a 'return' statement; - * executing the special `yyterminate()' action. + * executing the special 'yyterminate()' action. - * or, switching to a new buffer using `yy_switch_to_buffer()' as + * or, switching to a new buffer using 'yy_switch_to_buffer()' as shown in the example above. <<EOF>> rules may not be used with other patterns; they may only be qualified with a list of start conditions. If an unqualified <<EOF>> -rule is given, it applies to _all_ start conditions which do not -already have <<EOF>> actions. To specify an <<EOF>> rule for only the -initial start condition, use: +rule is given, it applies to _all_ start conditions which do not already +have <<EOF>> actions. To specify an <<EOF>> rule for only the initial +start condition, use: <INITIAL><<EOF>> @@ -1873,57 +1872,57 @@ File: flex.info, Node: Misc Macros, Next: User Values, Prev: EOF, Up: Top 13 Miscellaneous Macros *********************** -The macro `YY_USER_ACTION' can be defined to provide an action which is +The macro 'YY_USER_ACTION' can be defined to provide an action which is always executed prior to the matched rule's action. For example, it could be #define'd to call a routine to convert yytext to lower-case. -When `YY_USER_ACTION' is invoked, the variable `yy_act' gives the -number of the matched rule (rules are numbered starting with 1). -Suppose you want to profile how often each of your rules is matched. -The following would do the trick: +When 'YY_USER_ACTION' is invoked, the variable 'yy_act' gives the number +of the matched rule (rules are numbered starting with 1). Suppose you +want to profile how often each of your rules is matched. The following +would do the trick: #define YY_USER_ACTION ++ctr[yy_act] - where `ctr' is an array to hold the counts for the different rules. -Note that the macro `YY_NUM_RULES' gives the total number of rules -(including the default rule), even if you use `-s)', so a correct -declaration for `ctr' is: + where 'ctr' is an array to hold the counts for the different rules. +Note that the macro 'YY_NUM_RULES' gives the total number of rules +(including the default rule), even if you use '-s)', so a correct +declaration for 'ctr' is: int ctr[YY_NUM_RULES]; - The macro `YY_USER_INIT' may be defined to provide an action which -is always executed before the first scan (and before the scanner's -internal initializations are done). For example, it could be used to -call a routine to read in a data table or open a logging file. - - The macro `yy_set_interactive(is_interactive)' can be used to -control whether the current buffer is considered "interactive". An -interactive buffer is processed more slowly, but must be used when the -scanner's input source is indeed interactive to avoid problems due to -waiting to fill buffers (see the discussion of the `-I' flag in *note -Scanner Options::). A non-zero value in the macro invocation marks the -buffer as interactive, a zero value as non-interactive. Note that use -of this macro overrides `%option always-interactive' or `%option -never-interactive' (*note Scanner Options::). `yy_set_interactive()' + The macro 'YY_USER_INIT' may be defined to provide an action which is +always executed before the first scan (and before the scanner's internal +initializations are done). For example, it could be used to call a +routine to read in a data table or open a logging file. + + The macro 'yy_set_interactive(is_interactive)' can be used to control +whether the current buffer is considered "interactive". An interactive +buffer is processed more slowly, but must be used when the scanner's +input source is indeed interactive to avoid problems due to waiting to +fill buffers (see the discussion of the '-I' flag in *note Scanner +Options::). A non-zero value in the macro invocation marks the buffer +as interactive, a zero value as non-interactive. Note that use of this +macro overrides '%option always-interactive' or '%option +never-interactive' (*note Scanner Options::). 'yy_set_interactive()' must be invoked prior to beginning to scan the buffer that is (or is not) to be considered interactive. - The macro `yy_set_bol(at_bol)' can be used to control whether the + The macro 'yy_set_bol(at_bol)' can be used to control whether the current buffer's scanning context for the next token match is done as though at the beginning of a line. A non-zero macro argument makes -rules anchored with `^' active, while a zero argument makes `^' rules +rules anchored with '^' active, while a zero argument makes '^' rules inactive. - The macro `YY_AT_BOL()' returns true if the next token scanned from -the current buffer will have `^' rules active, false otherwise. + The macro 'YY_AT_BOL()' returns true if the next token scanned from +the current buffer will have '^' rules active, false otherwise. In the generated scanner, the actions are all gathered in one large -switch statement and separated using `YY_BREAK', which may be -redefined. By default, it is simply a `break', to separate each rule's -action from the following rule's. Redefining `YY_BREAK' allows, for -example, C++ users to #define YY_BREAK to do nothing (while being very -careful that every rule ends with a `break' or a `return'!) to avoid -suffering from unreachable statement warnings where because a rule's -action ends with `return', the `YY_BREAK' is inaccessible. +switch statement and separated using 'YY_BREAK', which may be redefined. +By default, it is simply a 'break', to separate each rule's action from +the following rule's. Redefining 'YY_BREAK' allows, for example, C++ +users to #define YY_BREAK to do nothing (while being very careful that +every rule ends with a 'break' or a 'return'!) to avoid suffering from +unreachable statement warnings where because a rule's action ends with +'return', the 'YY_BREAK' is inaccessible. File: flex.info, Node: User Values, Next: Yacc, Prev: Misc Macros, Up: Top @@ -1934,53 +1933,52 @@ File: flex.info, Node: User Values, Next: Yacc, Prev: Misc Macros, Up: Top This chapter summarizes the various values available to the user in the rule actions. -`char *yytext' +'char *yytext' holds the text of the current token. It may be modified but not lengthened (you cannot append characters to the end). - If the special directive `%array' appears in the first section of - the scanner description, then `yytext' is instead declared `char - yytext[YYLMAX]', where `YYLMAX' is a macro definition that you can + If the special directive '%array' appears in the first section of + the scanner description, then 'yytext' is instead declared 'char + yytext[YYLMAX]', where 'YYLMAX' is a macro definition that you can redefine in the first section if you don't like the default value - (generally 8KB). Using `%array' results in somewhat slower - scanners, but the value of `yytext' becomes immune to calls to - `unput()', which potentially destroy its value when `yytext' is a - character pointer. The opposite of `%array' is `%pointer', which + (generally 8KB). Using '%array' results in somewhat slower + scanners, but the value of 'yytext' becomes immune to calls to + 'unput()', which potentially destroy its value when 'yytext' is a + character pointer. The opposite of '%array' is '%pointer', which is the default. - You cannot use `%array' when generating C++ scanner classes (the - `-+' flag). + You cannot use '%array' when generating C++ scanner classes (the + '-+' flag). -`int yyleng' +'int yyleng' holds the length of the current token. -`FILE *yyin' - is the file which by default `flex' reads from. It may be +'FILE *yyin' + is the file which by default 'flex' reads from. It may be redefined but doing so only makes sense before scanning begins or after an EOF has been encountered. Changing it in the midst of - scanning will have unexpected results since `flex' buffers its - input; use `yyrestart()' instead. Once scanning terminates - because an end-of-file has been seen, you can assign `yyin' at the - new input file and then call the scanner again to continue - scanning. - -`void yyrestart( FILE *new_file )' - may be called to point `yyin' at the new input file. The + scanning will have unexpected results since 'flex' buffers its + input; use 'yyrestart()' instead. Once scanning terminates because + an end-of-file has been seen, you can assign 'yyin' at the new + input file and then call the scanner again to continue scanning. + +'void yyrestart( FILE *new_file )' + may be called to point 'yyin' at the new input file. The switch-over to the new file is immediate (any previously - buffered-up input is lost). Note that calling `yyrestart()' with - `yyin' as an argument thus throws away the current input buffer - and continues scanning the same input file. + buffered-up input is lost). Note that calling 'yyrestart()' with + 'yyin' as an argument thus throws away the current input buffer and + continues scanning the same input file. -`FILE *yyout' - is the file to which `ECHO' actions are done. It can be reassigned +'FILE *yyout' + is the file to which 'ECHO' actions are done. It can be reassigned by the user. -`YY_CURRENT_BUFFER' - returns a `YY_BUFFER_STATE' handle to the current buffer. +'YY_CURRENT_BUFFER' + returns a 'YY_BUFFER_STATE' handle to the current buffer. -`YY_START' +'YY_START' returns an integer value corresponding to the current start - condition. You can subsequently use this value with `BEGIN' to + condition. You can subsequently use this value with 'BEGIN' to return to that start condition. @@ -1989,15 +1987,15 @@ File: flex.info, Node: Yacc, Next: Scanner Options, Prev: User Values, Up: T 15 Interfacing with Yacc ************************ -One of the main uses of `flex' is as a companion to the `yacc' -parser-generator. `yacc' parsers expect to call a routine named -`yylex()' to find the next input token. The routine is supposed to +One of the main uses of 'flex' is as a companion to the 'yacc' +parser-generator. 'yacc' parsers expect to call a routine named +'yylex()' to find the next input token. The routine is supposed to return the type of the next token as well as putting any associated -value in the global `yylval'. To use `flex' with `yacc', one specifies -the `-d' option to `yacc' to instruct it to generate the file `y.tab.h' -containing definitions of all the `%tokens' appearing in the `yacc' -input. This file is then included in the `flex' scanner. For example, -if one of the tokens is `TOK_NUMBER', part of the scanner might look +value in the global 'yylval'. To use 'flex' with 'yacc', one specifies +the '-d' option to 'yacc' to instruct it to generate the file 'y.tab.h' +containing definitions of all the '%tokens' appearing in the 'yacc' +input. This file is then included in the 'flex' scanner. For example, +if one of the tokens is 'TOK_NUMBER', part of the scanner might look like: %{ @@ -2014,18 +2012,18 @@ File: flex.info, Node: Scanner Options, Next: Performance, Prev: Yacc, Up: T 16 Scanner Options ****************** -The various `flex' options are categorized by function in the following -menu. If you want to lookup a particular option by name, *Note Index of +The various 'flex' options are categorized by function in the following +menu. If you want to lookup a particular option by name, *Note Index of Scanner Options::. * Menu: -* Options for Specifying Filenames:: -* Options Affecting Scanner Behavior:: -* Code-Level And API Options:: -* Options for Scanner Speed and Size:: -* Debugging Options:: -* Miscellaneous Options:: +* Options for Specifying Filenames:: +* Options Affecting Scanner Behavior:: +* Code-Level And API Options:: +* Options for Scanner Speed and Size:: +* Debugging Options:: +* Miscellaneous Options:: Even though there are many scanner options, a typical scanner might only specify the following options: @@ -2035,34 +2033,34 @@ only specify the following options: %option yylineno %option outfile="scanner.c" header-file="scanner.h" - The first line specifies the general type of scanner we want. The -second line specifies that we are being careful. The third line asks -flex to track line numbers. The last line tells flex what to name the -files. (The options can be specified in any order. We just divided + The first line specifies the general type of scanner we want. The +second line specifies that we are being careful. The third line asks +flex to track line numbers. The last line tells flex what to name the +files. (The options can be specified in any order. We just divided them.) - `flex' also provides a mechanism for controlling options within the + 'flex' also provides a mechanism for controlling options within the scanner specification itself, rather than from the flex command-line. -This is done by including `%option' directives in the first section of +This is done by including '%option' directives in the first section of the scanner specification. You can specify multiple options with a -single `%option' directive, and multiple directives in the first -section of your flex input file. +single '%option' directive, and multiple directives in the first section +of your flex input file. Most options are given simply as names, optionally preceded by the -word `no' (with no intervening whitespace) to negate their meaning. -The names are the same as their long-option equivalents (but without the -leading `--' ). +word 'no' (with no intervening whitespace) to negate their meaning. The +names are the same as their long-option equivalents (but without the +leading '--' ). - `flex' scans your rule actions to determine whether you use the -`REJECT' or `yymore()' features. The `REJECT' and `yymore' options are + 'flex' scans your rule actions to determine whether you use the +'REJECT' or 'yymore()' features. The 'REJECT' and 'yymore' options are available to override its decision as to whether you use the options, -either by setting them (e.g., `%option reject)' to indicate the feature +either by setting them (e.g., '%option reject)' to indicate the feature is indeed used, or unsetting them to indicate it actually is not used -(e.g., `%option noyymore)'. +(e.g., '%option noyymore)'. A number of options are available for lint purists who want to suppress the appearance of unneeded routines in the generated scanner. -Each of the following, if unset (e.g., `%option nounput'), results in +Each of the following, if unset (e.g., '%option nounput'), results in the corresponding routine not appearing in the generated scanner: input, unput @@ -2074,8 +2072,8 @@ the corresponding routine not appearing in the generated scanner: yyget_out, yyset_out, yyget_lval, yyset_lval, yyget_lloc, yyset_lloc, yyget_debug, yyset_debug - (though `yy_push_state()' and friends won't appear anyway unless you -use `%option stack)'. + (though 'yy_push_state()' and friends won't appear anyway unless you +use '%option stack)'. File: flex.info, Node: Options for Specifying Filenames, Next: Options Affecting Scanner Behavior, Prev: Scanner Options, Up: Scanner Options @@ -2083,86 +2081,84 @@ File: flex.info, Node: Options for Specifying Filenames, Next: Options Affecti 16.1 Options for Specifying Filenames ===================================== -`--header-file=FILE, `%option header-file="FILE"'' - instructs flex to write a C header to `FILE'. This file contains +'--header-file=FILE, '%option header-file="FILE"'' + instructs flex to write a C header to 'FILE'. This file contains function prototypes, extern variables, and types used by the scanner. Only the external API is exported by the header file. Many macros that are usable from within scanner actions are not - exported to the header file. This is due to namespace problems and + exported to the header file. This is due to namespace problems and the goal of a clean external API. - While in the header, the macro `yyIN_HEADER' is defined, where `yy' + While in the header, the macro 'yyIN_HEADER' is defined, where 'yy' is substituted with the appropriate prefix. - The `--header-file' option is not compatible with the `--c++' + The '--header-file' option is not compatible with the '--c++' option, since the C++ scanner provides its own header in - `yyFlexLexer.h'. + 'yyFlexLexer.h'. -`-oFILE, --outfile=FILE, `%option outfile="FILE"'' - directs flex to write the scanner to the file `FILE' instead of - `lex.yy.c'. If you combine `--outfile' with the `--stdout' option, - then the scanner is written to `stdout' but its `#line' directives - (see the `-l' option above) refer to the file `FILE'. +'-oFILE, --outfile=FILE, '%option outfile="FILE"'' + directs flex to write the scanner to the file 'FILE' instead of + 'lex.yy.c'. If you combine '--outfile' with the '--stdout' option, + then the scanner is written to 'stdout' but its '#line' directives + (see the '-l' option above) refer to the file 'FILE'. -`-t, --stdout, `%option stdout'' - instructs `flex' to write the scanner it generates to standard - output instead of `lex.yy.c'. +'-t, --stdout, '%option stdout'' + instructs 'flex' to write the scanner it generates to standard + output instead of 'lex.yy.c'. -`-SFILE, --skel=FILE' - overrides the default skeleton file from which `flex' constructs +'-SFILE, --skel=FILE' + overrides the default skeleton file from which 'flex' constructs its scanners. You'll never need this option unless you are doing - `flex' maintenance or development. + 'flex' maintenance or development. -`--tables-file=FILE' +'--tables-file=FILE' Write serialized scanner dfa tables to FILE. The generated scanner will not contain the tables, and requires them to be loaded at runtime. *Note serialization::. -`--tables-verify' - This option is for flex development. We document it here in case +'--tables-verify' + This option is for flex development. We document it here in case you stumble upon it by accident or in case you suspect some inconsistency in the serialized tables. Flex will serialize the scanner dfa tables but will also generate the in-code tables as it - normally does. At runtime, the scanner will verify that the + normally does. At runtime, the scanner will verify that the serialized tables match the in-code tables, instead of loading them. - File: flex.info, Node: Options Affecting Scanner Behavior, Next: Code-Level And API Options, Prev: Options for Specifying Filenames, Up: Scanner Options 16.2 Options Affecting Scanner Behavior ======================================= -`-i, --case-insensitive, `%option case-insensitive'' - instructs `flex' to generate a "case-insensitive" scanner. The - case of letters given in the `flex' input patterns will be ignored, +'-i, --case-insensitive, '%option case-insensitive'' + instructs 'flex' to generate a "case-insensitive" scanner. The + case of letters given in the 'flex' input patterns will be ignored, and tokens in the input will be matched regardless of case. The - matched text given in `yytext' will have the preserved case (i.e., + matched text given in 'yytext' will have the preserved case (i.e., it will not be folded). For tricky behavior, see *note case and character ranges::. -`-l, --lex-compat, `%option lex-compat'' - turns on maximum compatibility with the original AT&T `lex' +'-l, --lex-compat, '%option lex-compat'' + turns on maximum compatibility with the original AT&T 'lex' implementation. Note that this does not mean _full_ compatibility. Use of this option costs a considerable amount of performance, and - it cannot be used with the `--c++', `--full', `--fast', `-Cf', or - `-CF' options. For details on the compatibilities it provides, see + it cannot be used with the '--c++', '--full', '--fast', '-Cf', or + '-CF' options. For details on the compatibilities it provides, see *note Lex and Posix::. This option also results in the name - `YY_FLEX_LEX_COMPAT' being `#define''d in the generated scanner. + 'YY_FLEX_LEX_COMPAT' being '#define''d in the generated scanner. -`-B, --batch, `%option batch'' - instructs `flex' to generate a "batch" scanner, the opposite of - _interactive_ scanners generated by `--interactive' (see below). - In general, you use `-B' when you are _certain_ that your scanner +'-B, --batch, '%option batch'' + instructs 'flex' to generate a "batch" scanner, the opposite of + _interactive_ scanners generated by '--interactive' (see below). + In general, you use '-B' when you are _certain_ that your scanner will never be used interactively, and you want to squeeze a _little_ more performance out of it. If your goal is instead to - squeeze out a _lot_ more performance, you should be using the - `-Cf' or `-CF' options, which turn on `--batch' automatically - anyway. + squeeze out a _lot_ more performance, you should be using the '-Cf' + or '-CF' options, which turn on '--batch' automatically anyway. -`-I, --interactive, `%option interactive'' - instructs `flex' to generate an interactive scanner. An +'-I, --interactive, '%option interactive'' + instructs 'flex' to generate an interactive scanner. An interactive scanner is one that only looks ahead to decide what token has been matched if it absolutely must. It turns out that always looking one extra character ahead, even if the scanner has @@ -2173,113 +2169,112 @@ File: flex.info, Node: Options Affecting Scanner Behavior, Next: Code-Level An newline token until they enter _another_ token, which often means typing in another whole line. - `flex' scanners default to `interactive' unless you use the `-Cf' - or `-CF' table-compression options (*note Performance::). That's + 'flex' scanners default to 'interactive' unless you use the '-Cf' + or '-CF' table-compression options (*note Performance::). That's because if you're looking for high-performance you should be using - one of these options, so if you didn't, `flex' assumes you'd - rather trade off a bit of run-time performance for intuitive - interactive behavior. Note also that you _cannot_ use - `--interactive' in conjunction with `-Cf' or `-CF'. Thus, this - option is not really needed; it is on by default for all those - cases in which it is allowed. + one of these options, so if you didn't, 'flex' assumes you'd rather + trade off a bit of run-time performance for intuitive interactive + behavior. Note also that you _cannot_ use '--interactive' in + conjunction with '-Cf' or '-CF'. Thus, this option is not really + needed; it is on by default for all those cases in which it is + allowed. - You can force a scanner to _not_ be interactive by using `--batch' + You can force a scanner to _not_ be interactive by using '--batch' -`-7, --7bit, `%option 7bit'' - instructs `flex' to generate a 7-bit scanner, i.e., one which can +'-7, --7bit, '%option 7bit'' + instructs 'flex' to generate a 7-bit scanner, i.e., one which can only recognize 7-bit characters in its input. The advantage of - using `--7bit' is that the scanner's tables can be up to half the - size of those generated using the `--8bit'. The disadvantage is + using '--7bit' is that the scanner's tables can be up to half the + size of those generated using the '--8bit'. The disadvantage is that such scanners often hang or crash if their input contains an 8-bit character. Note, however, that unless you generate your scanner using the - `-Cf' or `-CF' table compression options, use of `--7bit' will - save only a small amount of table space, and make your scanner - considerably less portable. `Flex''s default behavior is to - generate an 8-bit scanner unless you use the `-Cf' or `-CF', in - which case `flex' defaults to generating 7-bit scanners unless - your site was always configured to generate 8-bit scanners (as will + '-Cf' or '-CF' table compression options, use of '--7bit' will save + only a small amount of table space, and make your scanner + considerably less portable. 'Flex''s default behavior is to + generate an 8-bit scanner unless you use the '-Cf' or '-CF', in + which case 'flex' defaults to generating 7-bit scanners unless your + site was always configured to generate 8-bit scanners (as will often be the case with non-USA sites). You can tell whether flex generated a 7-bit or an 8-bit scanner by inspecting the flag - summary in the `--verbose' output as described above. + summary in the '--verbose' output as described above. - Note that if you use `-Cfe' or `-CFe' `flex' still defaults to + Note that if you use '-Cfe' or '-CFe' 'flex' still defaults to generating an 8-bit scanner, since usually with these compression options full 8-bit tables are not much more expensive than 7-bit tables. -`-8, --8bit, `%option 8bit'' - instructs `flex' to generate an 8-bit scanner, i.e., one which can +'-8, --8bit, '%option 8bit'' + instructs 'flex' to generate an 8-bit scanner, i.e., one which can recognize 8-bit characters. This flag is only needed for scanners - generated using `-Cf' or `-CF', as otherwise flex defaults to + generated using '-Cf' or '-CF', as otherwise flex defaults to generating an 8-bit scanner anyway. - See the discussion of `--7bit' above for `flex''s default behavior + See the discussion of '--7bit' above for 'flex''s default behavior and the tradeoffs between 7-bit and 8-bit scanners. -`--default, `%option default'' +'--default, '%option default'' generate the default rule. -`--always-interactive, `%option always-interactive'' +'--always-interactive, '%option always-interactive'' instructs flex to generate a scanner which always considers its input _interactive_. Normally, on each new input file the scanner - calls `isatty()' in an attempt to determine whether the scanner's + calls 'isatty()' in an attempt to determine whether the scanner's input source is interactive and thus should be read a character at a time. When this option is used, however, then no such call is made. -`--never-interactive, `--never-interactive'' +'--never-interactive, '--never-interactive'' instructs flex to generate a scanner which never considers its - input interactive. This is the opposite of `always-interactive'. + input interactive. This is the opposite of 'always-interactive'. -`-X, --posix, `%option posix'' +'-X, --posix, '%option posix'' turns on maximum compatibility with the POSIX 1003.2-1992 - definition of `lex'. Since `flex' was originally designed to - implement the POSIX definition of `lex' this generally involves + definition of 'lex'. Since 'flex' was originally designed to + implement the POSIX definition of 'lex' this generally involves very few changes in behavior. At the current writing the known - differences between `flex' and the POSIX standard are: + differences between 'flex' and the POSIX standard are: - * In POSIX and AT&T `lex', the repeat operator, `{}', has lower - precedence than concatenation (thus `ab{3}' yields `ababab'). + * In POSIX and AT&T 'lex', the repeat operator, '{}', has lower + precedence than concatenation (thus 'ab{3}' yields 'ababab'). Most POSIX utilities use an Extended Regular Expression (ERE) precedence that has the precedence of the repeat operator - higher than concatenation (which causes `ab{3}' to yield - `abbb'). By default, `flex' places the precedence of the + higher than concatenation (which causes 'ab{3}' to yield + 'abbb'). By default, 'flex' places the precedence of the repeat operator higher than concatenation which matches the ERE processing of other POSIX utilities. When either - `--posix' or `-l' are specified, `flex' will use the - traditional AT&T and POSIX-compliant precedence for the - repeat operator where concatenation has higher precedence - than the repeat operator. + '--posix' or '-l' are specified, 'flex' will use the + traditional AT&T and POSIX-compliant precedence for the repeat + operator where concatenation has higher precedence than the + repeat operator. -`--stack, `%option stack'' +'--stack, '%option stack'' enables the use of start condition stacks (*note Start Conditions::). -`--stdinit, `%option stdinit'' - if set (i.e., %option stdinit) initializes `yyin' and `yyout' to - `stdin' and `stdout', instead of the default of `NULL'. Some - existing `lex' programs depend on this behavior, even though it is - not compliant with ANSI C, which does not require `stdin' and - `stdout' to be compile-time constant. In a reentrant scanner, - however, this is not a problem since initialization is performed - in `yylex_init' at runtime. - -`--yylineno, `%option yylineno'' - directs `flex' to generate a scanner that maintains the number of +'--stdinit, '%option stdinit'' + if set (i.e., %option stdinit) initializes 'yyin' and 'yyout' to + 'stdin' and 'stdout', instead of the default of 'NULL'. Some + existing 'lex' programs depend on this behavior, even though it is + not compliant with ANSI C, which does not require 'stdin' and + 'stdout' to be compile-time constant. In a reentrant scanner, + however, this is not a problem since initialization is performed in + 'yylex_init' at runtime. + +'--yylineno, '%option yylineno'' + directs 'flex' to generate a scanner that maintains the number of the current line read from its input in the global variable - `yylineno'. This option is implied by `%option lex-compat'. In a - reentrant C scanner, the macro `yylineno' is accessible regardless - of the value of `%option yylineno', however, its value is not - modified by `flex' unless `%option yylineno' is enabled. - -`--yywrap, `%option yywrap'' - if unset (i.e., `--noyywrap)', makes the scanner not call - `yywrap()' upon an end-of-file, but simply assume that there are no - more files to scan (until the user points `yyin' at a new file and - calls `yylex()' again). + 'yylineno'. This option is implied by '%option lex-compat'. In a + reentrant C scanner, the macro 'yylineno' is accessible regardless + of the value of '%option yylineno', however, its value is not + modified by 'flex' unless '%option yylineno' is enabled. +'--yywrap, '%option yywrap'' + if unset (i.e., '--noyywrap)', makes the scanner not call + 'yywrap()' upon an end-of-file, but simply assume that there are no + more files to scan (until the user points 'yyin' at a new file and + calls 'yylex()' again). File: flex.info, Node: Code-Level And API Options, Next: Options for Scanner Speed and Size, Prev: Options Affecting Scanner Behavior, Up: Scanner Options @@ -2287,68 +2282,67 @@ File: flex.info, Node: Code-Level And API Options, Next: Options for Scanner S 16.3 Code-Level And API Options =============================== -`--ansi-definitions, `%option ansi-definitions'' - instruct flex to generate ANSI C99 definitions for functions. - This option is enabled by default. If `%option - noansi-definitions' is specified, then the obsolete style is - generated. +'--ansi-definitions, '%option ansi-definitions'' + instruct flex to generate ANSI C99 definitions for functions. This + option is enabled by default. If '%option noansi-definitions' is + specified, then the obsolete style is generated. -`--ansi-prototypes, `%option ansi-prototypes'' - instructs flex to generate ANSI C99 prototypes for functions. - This option is enabled by default. If `noansi-prototypes' is - specified, then prototypes will have empty parameter lists. +'--ansi-prototypes, '%option ansi-prototypes'' + instructs flex to generate ANSI C99 prototypes for functions. This + option is enabled by default. If 'noansi-prototypes' is specified, + then prototypes will have empty parameter lists. -`--bison-bridge, `%option bison-bridge'' +'--bison-bridge, '%option bison-bridge'' instructs flex to generate a C scanner that is meant to be called - by a `GNU bison' parser. The scanner has minor API changes for - `bison' compatibility. In particular, the declaration of `yylex' - is modified to take an additional parameter, `yylval'. *Note - Bison Bridge::. - -`--bison-locations, `%option bison-locations'' - instruct flex that `GNU bison' `%locations' are being used. This - means `yylex' will be passed an additional parameter, `yylloc'. - This option implies `%option bison-bridge'. *Note Bison Bridge::. - -`-L, --noline, `%option noline'' - instructs `flex' not to generate `#line' directives. Without this - option, `flex' peppers the generated scanner with `#line' + by a 'GNU bison' parser. The scanner has minor API changes for + 'bison' compatibility. In particular, the declaration of 'yylex' + is modified to take an additional parameter, 'yylval'. *Note Bison + Bridge::. + +'--bison-locations, '%option bison-locations'' + instruct flex that 'GNU bison' '%locations' are being used. This + means 'yylex' will be passed an additional parameter, 'yylloc'. + This option implies '%option bison-bridge'. *Note Bison Bridge::. + +'-L, --noline, '%option noline'' + instructs 'flex' not to generate '#line' directives. Without this + option, 'flex' peppers the generated scanner with '#line' directives so error messages in the actions will be correctly - located with respect to either the original `flex' input file (if - the errors are due to code in the input file), or `lex.yy.c' (if - the errors are `flex''s fault - you should report these sorts of + located with respect to either the original 'flex' input file (if + the errors are due to code in the input file), or 'lex.yy.c' (if + the errors are 'flex''s fault - you should report these sorts of errors to the email address given in *note Reporting Bugs::). -`-R, --reentrant, `%option reentrant'' +'-R, --reentrant, '%option reentrant'' instructs flex to generate a reentrant C scanner. The generated - scanner may safely be used in a multi-threaded environment. The + scanner may safely be used in a multi-threaded environment. The API for a reentrant scanner is different than for a non-reentrant scanner *note Reentrant::). Because of the API difference between - reentrant and non-reentrant `flex' scanners, non-reentrant flex + reentrant and non-reentrant 'flex' scanners, non-reentrant flex code must be modified before it is suitable for use with this - option. This option is not compatible with the `--c++' option. + option. This option is not compatible with the '--c++' option. - The option `--reentrant' does not affect the performance of the + The option '--reentrant' does not affect the performance of the scanner. -`-+, --c++, `%option c++'' +'-+, --c++, '%option c++'' specifies that you want flex to generate a C++ scanner class. *Note Cxx::, for details. -`--array, `%option array'' +'--array, '%option array'' specifies that you want yytext to be an array instead of a char* -`--pointer, `%option pointer'' - specify that `yytext' should be a `char *', not an array. This - default is `char *'. +'--pointer, '%option pointer'' + specify that 'yytext' should be a 'char *', not an array. This + default is 'char *'. -`-PPREFIX, --prefix=PREFIX, `%option prefix="PREFIX"'' - changes the default `yy' prefix used by `flex' for all +'-PPREFIX, --prefix=PREFIX, '%option prefix="PREFIX"'' + changes the default 'yy' prefix used by 'flex' for all globally-visible variable and function names to instead be - `PREFIX'. For example, `--prefix=foo' changes the name of - `yytext' to `footext'. It also changes the name of the default - output file from `lex.yy.c' to `lex.foo.c'. Here is a partial - list of the names affected: + 'PREFIX'. For example, '--prefix=foo' changes the name of 'yytext' + to 'footext'. It also changes the name of the default output file + from 'lex.yy.c' to 'lex.foo.c'. Here is a partial list of the + names affected: yy_create_buffer yy_delete_buffer @@ -2369,41 +2363,40 @@ File: flex.info, Node: Code-Level And API Options, Next: Options for Scanner S yyrealloc yyfree - (If you are using a C++ scanner, then only `yywrap' and - `yyFlexLexer' are affected.) Within your scanner itself, you can + (If you are using a C++ scanner, then only 'yywrap' and + 'yyFlexLexer' are affected.) Within your scanner itself, you can still refer to the global variables and functions using either version of their name; but externally, they have the modified name. - This option lets you easily link together multiple `flex' programs + This option lets you easily link together multiple 'flex' programs into the same executable. Note, though, that using this option - also renames `yywrap()', so you now _must_ either provide your own + also renames 'yywrap()', so you now _must_ either provide your own (appropriately-named) version of the routine for your scanner, or - use `%option noyywrap', as linking with `-lfl' no longer provides + use '%option noyywrap', as linking with '-lfl' no longer provides one for you by default. -`--main, `%option main'' - directs flex to provide a default `main()' program for the - scanner, which simply calls `yylex()'. This option implies - `noyywrap' (see below). - -`--nounistd, `%option nounistd'' - suppresses inclusion of the non-ANSI header file `unistd.h'. This - option is meant to target environments in which `unistd.h' does - not exist. Be aware that certain options may cause flex to - generate code that relies on functions normally found in - `unistd.h', (e.g. `isatty()', `read()'.) If you wish to use these - functions, you will have to inform your compiler where to find - them. *Note option-always-interactive::. *Note option-read::. - -`--yyclass=NAME, `%option yyclass="NAME"'' - only applies when generating a C++ scanner (the `--c++' option). - It informs `flex' that you have derived `NAME' as a subclass of - `yyFlexLexer', so `flex' will place your actions in the member - function `foo::yylex()' instead of `yyFlexLexer::yylex()'. It - also generates a `yyFlexLexer::yylex()' member function that emits - a run-time error (by invoking `yyFlexLexer::LexerError())' if - called. *Note Cxx::. - +'--main, '%option main'' + directs flex to provide a default 'main()' program for the scanner, + which simply calls 'yylex()'. This option implies 'noyywrap' (see + below). + +'--nounistd, '%option nounistd'' + suppresses inclusion of the non-ANSI header file 'unistd.h'. This + option is meant to target environments in which 'unistd.h' does not + exist. Be aware that certain options may cause flex to generate + code that relies on functions normally found in 'unistd.h', (e.g. + 'isatty()', 'read()'.) If you wish to use these functions, you + will have to inform your compiler where to find them. *Note + option-always-interactive::. *Note option-read::. + +'--yyclass=NAME, '%option yyclass="NAME"'' + only applies when generating a C++ scanner (the '--c++' option). + It informs 'flex' that you have derived 'NAME' as a subclass of + 'yyFlexLexer', so 'flex' will place your actions in the member + function 'foo::yylex()' instead of 'yyFlexLexer::yylex()'. It also + generates a 'yyFlexLexer::yylex()' member function that emits a + run-time error (by invoking 'yyFlexLexer::LexerError())' if called. + *Note Cxx::. File: flex.info, Node: Options for Scanner Speed and Size, Next: Debugging Options, Prev: Code-Level And API Options, Up: Scanner Options @@ -2411,16 +2404,16 @@ File: flex.info, Node: Options for Scanner Speed and Size, Next: Debugging Opt 16.4 Options for Scanner Speed and Size ======================================= -`-C[aefFmr]' +'-C[aefFmr]' controls the degree of table compression and, more generally, trade-offs between small scanners and fast scanners. - `-C' - A lone `-C' specifies that the scanner tables should be + '-C' + A lone '-C' specifies that the scanner tables should be compressed but neither equivalence classes nor meta-equivalence classes should be used. - `-Ca, --align, `%option align'' + '-Ca, --align, '%option align'' ("align") instructs flex to trade off larger tables in the generated scanner for faster performance because the elements of the tables are better aligned for memory access and @@ -2429,10 +2422,10 @@ File: flex.info, Node: Options for Scanner Speed and Size, Next: Debugging Opt smaller-sized units such as shortwords. This option can quadruple the size of the tables used by your scanner. - `-Ce, --ecs, `%option ecs'' - directs `flex' to construct "equivalence classes", i.e., sets + '-Ce, --ecs, '%option ecs'' + directs 'flex' to construct "equivalence classes", i.e., sets of characters which have identical lexical properties (for - example, if the only appearance of digits in the `flex' input + example, if the only appearance of digits in the 'flex' input is in the character class "[0-9]" then the digits '0', '1', ..., '9' will all be put in the same equivalence class). Equivalence classes usually give dramatic reductions in the @@ -2440,44 +2433,44 @@ File: flex.info, Node: Options for Scanner Speed and Size, Next: Debugging Opt are pretty cheap performance-wise (one array look-up per character scanned). - `-Cf' + '-Cf' specifies that the "full" scanner tables should be generated - - `flex' should not compress the tables by taking advantages of + 'flex' should not compress the tables by taking advantages of similar transition functions for different states. - `-CF' + '-CF' specifies that the alternate fast scanner representation - (described above under the `--fast' flag) should be used. - This option cannot be used with `--c++'. + (described above under the '--fast' flag) should be used. + This option cannot be used with '--c++'. - `-Cm, --meta-ecs, `%option meta-ecs'' - directs `flex' to construct "meta-equivalence classes", which + '-Cm, --meta-ecs, '%option meta-ecs'' + directs 'flex' to construct "meta-equivalence classes", which are sets of equivalence classes (or characters, if equivalence classes are not being used) that are commonly used together. Meta-equivalence classes are often a big win when using - compressed tables, but they have a moderate performance - impact (one or two `if' tests and one array look-up per - character scanned). + compressed tables, but they have a moderate performance impact + (one or two 'if' tests and one array look-up per character + scanned). - `-Cr, --read, `%option read'' + '-Cr, --read, '%option read'' causes the generated scanner to _bypass_ use of the standard - I/O library (`stdio') for input. Instead of calling - `fread()' or `getc()', the scanner will use the `read()' - system call, resulting in a performance gain which varies - from system to system, but in general is probably negligible - unless you are also using `-Cf' or `-CF'. Using `-Cr' can - cause strange behavior if, for example, you read from `yyin' - using `stdio' prior to calling the scanner (because the - scanner will miss whatever text your previous reads left in - the `stdio' input buffer). `-Cr' has no effect if you define - `YY_INPUT()' (*note Generated Scanner::). - - The options `-Cf' or `-CF' and `-Cm' do not make sense together - + I/O library ('stdio') for input. Instead of calling 'fread()' + or 'getc()', the scanner will use the 'read()' system call, + resulting in a performance gain which varies from system to + system, but in general is probably negligible unless you are + also using '-Cf' or '-CF'. Using '-Cr' can cause strange + behavior if, for example, you read from 'yyin' using 'stdio' + prior to calling the scanner (because the scanner will miss + whatever text your previous reads left in the 'stdio' input + buffer). '-Cr' has no effect if you define 'YY_INPUT()' + (*note Generated Scanner::). + + The options '-Cf' or '-CF' and '-Cm' do not make sense together - there is no opportunity for meta-equivalence classes if the table is not being compressed. Otherwise the options may be freely mixed, and are cumulative. - The default setting is `-Cem', which specifies that `flex' should + The default setting is '-Cem', which specifies that 'flex' should generate equivalence classes and meta-equivalence classes. This setting provides the highest degree of table compression. You can trade off faster-executing scanners at the cost of larger tables @@ -2497,18 +2490,18 @@ File: flex.info, Node: Options for Scanner Speed and Size, Next: Debugging Opt and compiled the quickest, so during development you will usually want to use the default, maximal compression. - `-Cfe' is often a good compromise between speed and size for + '-Cfe' is often a good compromise between speed and size for production scanners. -`-f, --full, `%option full'' - specifies "fast scanner". No table compression is done and - `stdio' is bypassed. The result is large but fast. This option - is equivalent to `--Cfr' +'-f, --full, '%option full'' + specifies "fast scanner". No table compression is done and 'stdio' + is bypassed. The result is large but fast. This option is + equivalent to '--Cfr' -`-F, --fast, `%option fast'' +'-F, --fast, '%option fast'' specifies that the _fast_ scanner table representation should be - used (and `stdio' bypassed). This representation is about as fast - as the full table representation `--full', and for some sets of + used (and 'stdio' bypassed). This representation is about as fast + as the full table representation '--full', and for some sets of patterns will be considerably smaller (and for others, larger). In general, if the pattern set contains both _keywords_ and a catch-all, _identifier_ rule, such as in the set: @@ -2520,13 +2513,12 @@ File: flex.info, Node: Options for Scanner Speed and Size, Next: Debugging Opt [a-z]+ return TOK_ID; then you're better off using the full table representation. If - only the _identifier_ rule is present and you then use a hash - table or some such to detect the keywords, you're better off using - `--fast'. - - This option is equivalent to `-CFr'. It cannot be used with - `--c++'. + only the _identifier_ rule is present and you then use a hash table + or some such to detect the keywords, you're better off using + '--fast'. + This option is equivalent to '-CFr'. It cannot be used with + '--c++'. File: flex.info, Node: Debugging Options, Next: Miscellaneous Options, Prev: Options for Scanner Speed and Size, Up: Scanner Options @@ -2534,21 +2526,21 @@ File: flex.info, Node: Debugging Options, Next: Miscellaneous Options, Prev: 16.5 Debugging Options ====================== -`-b, --backup, `%option backup'' - Generate backing-up information to `lex.backup'. This is a list of +'-b, --backup, '%option backup'' + Generate backing-up information to 'lex.backup'. This is a list of scanner states which require backing up and the input characters on which they do so. By adding rules one can remove backing-up - states. If _all_ backing-up states are eliminated and `-Cf' or - `-CF' is used, the generated scanner will run faster (see the - `--perf-report' flag). Only users who wish to squeeze every last + states. If _all_ backing-up states are eliminated and '-Cf' or + '-CF' is used, the generated scanner will run faster (see the + '--perf-report' flag). Only users who wish to squeeze every last cycle out of their scanners need worry about this option. (*note Performance::). -`-d, --debug, `%option debug'' +'-d, --debug, '%option debug'' makes the generated scanner run in "debug" mode. Whenever a - pattern is recognized and the global variable `yy_flex_debug' is - non-zero (which is the default), the scanner will write to - `stderr' a line of the form: + pattern is recognized and the global variable 'yy_flex_debug' is + non-zero (which is the default), the scanner will write to 'stderr' + a line of the form: -accepting rule at line 53 ("the matched text") @@ -2559,66 +2551,64 @@ File: flex.info, Node: Debugging Options, Next: Miscellaneous Options, Prev: NUL; at this point, the two look the same as far as the scanner's concerned), or reaches an end-of-file. -`-p, --perf-report, `%option perf-report'' - generates a performance report to `stderr'. The report consists of - comments regarding features of the `flex' input file which will +'-p, --perf-report, '%option perf-report'' + generates a performance report to 'stderr'. The report consists of + comments regarding features of the 'flex' input file which will cause a serious loss of performance in the resulting scanner. If you give the flag twice, you will also get comments regarding features that lead to minor performance losses. - Note that the use of `REJECT', and variable trailing context - (*note Limitations::) entails a substantial performance penalty; - use of `yymore()', the `^' operator, and the `--interactive' flag - entail minor performance penalties. + Note that the use of 'REJECT', and variable trailing context (*note + Limitations::) entails a substantial performance penalty; use of + 'yymore()', the '^' operator, and the '--interactive' flag entail + minor performance penalties. -`-s, --nodefault, `%option nodefault'' +'-s, --nodefault, '%option nodefault'' causes the _default rule_ (that unmatched scanner input is echoed - to `stdout)' to be suppressed. If the scanner encounters input + to 'stdout)' to be suppressed. If the scanner encounters input that does not match any of its rules, it aborts with an error. This option is useful for finding holes in a scanner's rule set. -`-T, --trace, `%option trace'' - makes `flex' run in "trace" mode. It will generate a lot of - messages to `stderr' concerning the form of the input and the +'-T, --trace, '%option trace'' + makes 'flex' run in "trace" mode. It will generate a lot of + messages to 'stderr' concerning the form of the input and the resultant non-deterministic and deterministic finite automata. - This option is mostly for use in maintaining `flex'. + This option is mostly for use in maintaining 'flex'. -`-w, --nowarn, `%option nowarn'' +'-w, --nowarn, '%option nowarn'' suppresses warning messages. -`-v, --verbose, `%option verbose'' - specifies that `flex' should write to `stderr' a summary of +'-v, --verbose, '%option verbose'' + specifies that 'flex' should write to 'stderr' a summary of statistics regarding the scanner it generates. Most of the - statistics are meaningless to the casual `flex' user, but the - first line identifies the version of `flex' (same as reported by - `--version'), and the next line the flags used when generating the + statistics are meaningless to the casual 'flex' user, but the first + line identifies the version of 'flex' (same as reported by + '--version'), and the next line the flags used when generating the scanner, including those that are on by default. -`--warn, `%option warn'' - warn about certain things. In particular, if the default rule can +'--warn, '%option warn'' + warn about certain things. In particular, if the default rule can be matched but no default rule has been given, the flex will warn you. We recommend using this option always. - File: flex.info, Node: Miscellaneous Options, Prev: Debugging Options, Up: Scanner Options 16.6 Miscellaneous Options ========================== -`-c' +'-c' A do-nothing option included for POSIX compliance. -`-h, -?, --help' - generates a "help" summary of `flex''s options to `stdout' and - then exits. +'-h, -?, --help' + generates a "help" summary of 'flex''s options to 'stdout' and then + exits. -`-n' +'-n' Another do-nothing option included for POSIX compliance. -`-V, --version' - prints the version number to `stdout' and exits. - +'-V, --version' + prints the version number to 'stdout' and exits. File: flex.info, Node: Performance, Next: Cxx, Prev: Scanner Options, Up: Top @@ -2626,11 +2616,11 @@ File: flex.info, Node: Performance, Next: Cxx, Prev: Scanner Options, Up: To 17 Performance Considerations ***************************** -The main design goal of `flex' is that it generate high-performance +The main design goal of 'flex' is that it generate high-performance scanners. It has been optimized for dealing well with large sets of rules. Aside from the effects on scanner speed of the table compression -`-C' options outlined above, there are a number of options/actions -which degrade performance. These are, from most expensive to least: +'-C' options outlined above, there are a number of options/actions which +degrade performance. These are, from most expensive to least: REJECT arbitrary trailing context @@ -2646,21 +2636,21 @@ which degrade performance. These are, from most expensive to least: yymore() with the first two all being quite expensive and the last two being -quite cheap. Note also that `unput()' is implemented as a routine call -that potentially does quite a bit of work, while `yyless()' is a -quite-cheap macro. So if you are just putting back some excess text you -scanned, use `yyless()'. +quite cheap. Note also that 'unput()' is implemented as a routine call +that potentially does quite a bit of work, while 'yyless()' is a +quite-cheap macro. So if you are just putting back some excess text you +scanned, use 'yyless()'. - `REJECT' should be avoided at all costs when performance is + 'REJECT' should be avoided at all costs when performance is important. It is a particularly expensive option. - There is one case when `%option yylineno' can be expensive. That is + There is one case when '%option yylineno' can be expensive. That is when your patterns match long tokens that could _possibly_ contain a -newline character. There is no performance penalty for rules that can +newline character. There is no performance penalty for rules that can not possibly match newlines, since flex does not need to check them for -newlines. In general, you should avoid rules such as `[^f]+', which +newlines. In general, you should avoid rules such as '[^f]+', which match very long tokens, including newlines, and may possibly match your -entire file! A better approach is to separate `[^f]+' into two rules: +entire file! A better approach is to separate '[^f]+' into two rules: %option yylineno %% @@ -2671,7 +2661,7 @@ entire file! A better approach is to separate `[^f]+' into two rules: Getting rid of backing up is messy and often may be an enormous amount of work for a complicated scanner. In principal, one begins by -using the `-b' flag to generate a `lex.backup' file. For example, on +using the '-b' flag to generate a 'lex.backup' file. For example, on the input: %% @@ -2701,25 +2691,25 @@ the input: Compressed tables always back up. The first few lines tell us that there's a scanner state in which it -can make a transition on an 'o' but not on any other character, and -that in that state the currently scanned text does not match any rule. -The state occurs when trying to match the rules found at lines 2 and 3 -in the input file. If the scanner is in that state and then reads +can make a transition on an 'o' but not on any other character, and that +in that state the currently scanned text does not match any rule. The +state occurs when trying to match the rules found at lines 2 and 3 in +the input file. If the scanner is in that state and then reads something other than an 'o', it will have to back up to find a rule which is matched. With a bit of headscratching one can see that this -must be the state it's in when it has seen `fo'. When this has -happened, if anything other than another `o' is seen, the scanner will -have to back up to simply match the `f' (by the default rule). +must be the state it's in when it has seen 'fo'. When this has +happened, if anything other than another 'o' is seen, the scanner will +have to back up to simply match the 'f' (by the default rule). The comment regarding State #8 indicates there's a problem when -`foob' has been scanned. Indeed, on any character other than an `a', +'foob' has been scanned. Indeed, on any character other than an 'a', the scanner will have to back up to accept "foo". Similarly, the -comment for State #9 concerns when `fooba' has been scanned and an `r' +comment for State #9 concerns when 'fooba' has been scanned and an 'r' does not follow. The final comment reminds us that there's no point going to all the -trouble of removing backing up from the rules unless we're using `-Cf' -or `-CF', since there's no performance gain doing so with compressed +trouble of removing backing up from the rules unless we're using '-Cf' +or '-CF', since there's no performance gain doing so with compressed scanners. The way to remove the backing up is to add "error" rules: @@ -2750,16 +2740,16 @@ using a "catch-all" rule: it's not uncommon to get hundreds of messages. If one can decipher them, though, it often only takes a dozen or so rules to eliminate the backing up (though it's easy to make a mistake and have an error rule -accidentally match a valid token. A possible future `flex' feature -will be to automatically add rules to eliminate backing up). +accidentally match a valid token. A possible future 'flex' feature will +be to automatically add rules to eliminate backing up). It's important to keep in mind that you gain the benefits of -eliminating backing up only if you eliminate _every_ instance of -backing up. Leaving just one means you gain nothing. +eliminating backing up only if you eliminate _every_ instance of backing +up. Leaving just one means you gain nothing. _Variable_ trailing context (where both the leading and trailing parts do not have a fixed length) entails almost the same performance -loss as `REJECT' (i.e., substantial). So when possible a rule like: +loss as 'REJECT' (i.e., substantial). So when possible a rule like: %% mouse|rat/(cat|dog) run(); @@ -2776,15 +2766,15 @@ loss as `REJECT' (i.e., substantial). So when possible a rule like: mouse|rat/cat run(); mouse|rat/dog run(); - Note that here the special '|' action does _not_ provide any -savings, and can even make things worse (*note Limitations::). + Note that here the special '|' action does _not_ provide any savings, +and can even make things worse (*note Limitations::). Another area where the user can increase a scanner's performance (and one that's easier to implement) arises from the fact that the longer the tokens matched, the faster the scanner will run. This is because with long tokens the processing of most input characters takes place in the (short) inner scanning loop, and does not often have to go through the -additional work of setting up the scanning environment (e.g., `yytext') +additional work of setting up the scanning environment (e.g., 'yytext') for the action. Recall the scanner for C comments: %x comment @@ -2818,7 +2808,7 @@ keep the matched text as long as possible. Note that _adding_ rules does _not_ slow down the scanner! The speed of the scanner is independent of the number of rules or (modulo the considerations given at the beginning of this section) how complicated the rules are with -regard to operators such as `*' and `|'. +regard to operators such as '*' and '|'. A final example in speeding up a scanner: suppose you want to scan through a file containing identifiers and keywords, one per line and @@ -2866,15 +2856,15 @@ recognition of newlines with that of the other tokens: One has to be careful here, as we have now reintroduced backing up into the scanner. In particular, while _we_ know that there will never be any characters in the input stream other than letters or newlines, -`flex' can't figure this out, and it will plan for possibly needing to -back up when it has scanned a token like `auto' and then the next +'flex' can't figure this out, and it will plan for possibly needing to +back up when it has scanned a token like 'auto' and then the next character is something other than a newline or a letter. Previously it -would then just match the `auto' rule and be done, but now it has no -`auto' rule, only a `auto\n' rule. To eliminate the possibility of +would then just match the 'auto' rule and be done, but now it has no +'auto' rule, only a 'auto\n' rule. To eliminate the possibility of backing up, we could either duplicate all rules but without final newlines, or, since we never expect to encounter such an input and -therefore don't how it's classified, we can introduce one more -catch-all rule, this one which doesn't include a newline: +therefore don't how it's classified, we can introduce one more catch-all +rule, this one which doesn't include a newline: %% asm\n | @@ -2888,16 +2878,16 @@ catch-all rule, this one which doesn't include a newline: [a-z]+ | .|\n /* it's not a keyword */ - Compiled with `-Cf', this is about as fast as one can get a `flex' + Compiled with '-Cf', this is about as fast as one can get a 'flex' scanner to go for this particular problem. - A final note: `flex' is slow when matching `NUL's, particularly when -a token contains multiple `NUL's. It's best to write rules which match + A final note: 'flex' is slow when matching 'NUL's, particularly when +a token contains multiple 'NUL's. It's best to write rules which match _short_ amounts of text if it's anticipated that the text will often -include `NUL's. +include 'NUL's. Another final note regarding performance: as mentioned in *note -Matching::, dynamically resizing `yytext' to accommodate huge tokens is +Matching::, dynamically resizing 'yytext' to accommodate huge tokens is a slow process because it presently requires that the (huge) token be rescanned from the beginning. Thus if performance is vital, you should attempt to match "large" quantities of text but not "huge" quantities, @@ -2912,116 +2902,122 @@ File: flex.info, Node: Cxx, Next: Reentrant, Prev: Performance, Up: Top *IMPORTANT*: the present form of the scanning class is _experimental_ and may change considerably between major releases. - `flex' provides two different ways to generate scanners for use with -C++. The first way is to simply compile a scanner generated by `flex' + 'flex' provides two different ways to generate scanners for use with +C++. The first way is to simply compile a scanner generated by 'flex' using a C++ compiler instead of a C compiler. You should not encounter any compilation errors (*note Reporting Bugs::). You can then use C++ code in your rule actions instead of C code. Note that the default -input source for your scanner remains `yyin', and default echoing is -still done to `yyout'. Both of these remain `FILE *' variables and not +input source for your scanner remains 'yyin', and default echoing is +still done to 'yyout'. Both of these remain 'FILE *' variables and not C++ _streams_. - You can also use `flex' to generate a C++ scanner class, using the -`-+' option (or, equivalently, `%option c++)', which is automatically -specified if the name of the `flex' executable ends in a '+', such as -`flex++'. When using this option, `flex' defaults to generating the -scanner to the file `lex.yy.cc' instead of `lex.yy.c'. The generated -scanner includes the header file `FlexLexer.h', which defines the + You can also use 'flex' to generate a C++ scanner class, using the +'-+' option (or, equivalently, '%option c++)', which is automatically +specified if the name of the 'flex' executable ends in a '+', such as +'flex++'. When using this option, 'flex' defaults to generating the +scanner to the file 'lex.yy.cc' instead of 'lex.yy.c'. The generated +scanner includes the header file 'FlexLexer.h', which defines the interface to two C++ classes. - The first class, `FlexLexer', provides an abstract base class -defining the general scanner class interface. It provides the -following member functions: + The first class in 'FlexLexer.h', 'FlexLexer', provides an abstract +base class defining the general scanner class interface. It provides +the following member functions: -`const char* YYText()' - returns the text of the most recently matched token, the - equivalent of `yytext'. +'const char* YYText()' + returns the text of the most recently matched token, the equivalent + of 'yytext'. -`int YYLeng()' +'int YYLeng()' returns the length of the most recently matched token, the - equivalent of `yyleng'. + equivalent of 'yyleng'. -`int lineno() const' - returns the current input line number (see `%option yylineno)', or - `1' if `%option yylineno' was not used. +'int lineno() const' + returns the current input line number (see '%option yylineno)', or + '1' if '%option yylineno' was not used. -`void set_debug( int flag )' +'void set_debug( int flag )' sets the debugging flag for the scanner, equivalent to assigning to - `yy_flex_debug' (*note Scanner Options::). Note that you must - build the scanner using `%option debug' to include debugging + 'yy_flex_debug' (*note Scanner Options::). Note that you must + build the scanner using '%option debug' to include debugging information in it. -`int debug() const' +'int debug() const' returns the current setting of the debugging flag. Also provided are member functions equivalent to -`yy_switch_to_buffer()', `yy_create_buffer()' (though the first -argument is an `istream*' object pointer and not a `FILE*)', -`yy_flush_buffer()', `yy_delete_buffer()', and `yyrestart()' (again, -the first argument is a `istream*' object pointer). +'yy_switch_to_buffer()', 'yy_create_buffer()' (though the first argument +is an 'istream&' object reference and not a 'FILE*)', +'yy_flush_buffer()', 'yy_delete_buffer()', and 'yyrestart()' (again, the +first argument is a 'istream&' object reference). - The second class defined in `FlexLexer.h' is `yyFlexLexer', which is -derived from `FlexLexer'. It defines the following additional member + The second class defined in 'FlexLexer.h' is 'yyFlexLexer', which is +derived from 'FlexLexer'. It defines the following additional member functions: -`yyFlexLexer( istream* arg_yyin = 0, ostream* arg_yyout = 0 )' - constructs a `yyFlexLexer' object using the given streams for input - and output. If not specified, the streams default to `cin' and - `cout', respectively. - -`virtual int yylex()' - performs the same role is `yylex()' does for ordinary `flex' +'yyFlexLexer( istream* arg_yyin = 0, ostream* arg_yyout = 0 )' +'yyFlexLexer( istream& arg_yyin, ostream& arg_yyout )' + constructs a 'yyFlexLexer' object using the given streams for input + and output. If not specified, the streams default to 'cin' and + 'cout', respectively. 'yyFlexLexer' does not take ownership of its + stream arguments. It's up to the user to ensure the streams + pointed to remain alive at least as long as the 'yyFlexLexer' + instance. + +'virtual int yylex()' + performs the same role is 'yylex()' does for ordinary 'flex' scanners: it scans the input stream, consuming tokens, until a - rule's action returns a value. If you derive a subclass `S' from - `yyFlexLexer' and want to access the member functions and variables - of `S' inside `yylex()', then you need to use `%option - yyclass="S"' to inform `flex' that you will be using that subclass - instead of `yyFlexLexer'. In this case, rather than generating - `yyFlexLexer::yylex()', `flex' generates `S::yylex()' (and also - generates a dummy `yyFlexLexer::yylex()' that calls - `yyFlexLexer::LexerError()' if called). - -`virtual void switch_streams(istream* new_in = 0, ostream* new_out = 0)' - reassigns `yyin' to `new_in' (if non-null) and `yyout' to - `new_out' (if non-null), deleting the previous input buffer if - `yyin' is reassigned. - -`int yylex( istream* new_in, ostream* new_out = 0 )' - first switches the input streams via `switch_streams( new_in, - new_out )' and then returns the value of `yylex()'. - - In addition, `yyFlexLexer' defines the following protected virtual + rule's action returns a value. If you derive a subclass 'S' from + 'yyFlexLexer' and want to access the member functions and variables + of 'S' inside 'yylex()', then you need to use '%option yyclass="S"' + to inform 'flex' that you will be using that subclass instead of + 'yyFlexLexer'. In this case, rather than generating + 'yyFlexLexer::yylex()', 'flex' generates 'S::yylex()' (and also + generates a dummy 'yyFlexLexer::yylex()' that calls + 'yyFlexLexer::LexerError()' if called). + +'virtual void switch_streams(istream* new_in = 0, ostream* new_out = 0)' +'virtual void switch_streams(istream& new_in, ostream& new_out)' + reassigns 'yyin' to 'new_in' (if non-null) and 'yyout' to 'new_out' + (if non-null), deleting the previous input buffer if 'yyin' is + reassigned. + +'int yylex( istream* new_in, ostream* new_out = 0 )' +'int yylex( istream& new_in, ostream& new_out )' + first switches the input streams via 'switch_streams( new_in, + new_out )' and then returns the value of 'yylex()'. + + In addition, 'yyFlexLexer' defines the following protected virtual functions which you can redefine in derived classes to tailor the scanner: -`virtual int LexerInput( char* buf, int max_size )' - reads up to `max_size' characters into `buf' and returns the - number of characters read. To indicate end-of-input, return 0 - characters. Note that `interactive' scanners (see the `-B' and - `-I' flags in *note Scanner Options::) define the macro - `YY_INTERACTIVE'. If you redefine `LexerInput()' and need to take - different actions depending on whether or not the scanner might be - scanning an interactive input source, you can test for the - presence of this name via `#ifdef' statements. - -`virtual void LexerOutput( const char* buf, int size )' - writes out `size' characters from the buffer `buf', which, while - `NUL'-terminated, may also contain internal `NUL's if the - scanner's rules can match text with `NUL's in them. - -`virtual void LexerError( const char* msg )' +'virtual int LexerInput( char* buf, int max_size )' + reads up to 'max_size' characters into 'buf' and returns the number + of characters read. To indicate end-of-input, return 0 characters. + Note that 'interactive' scanners (see the '-B' and '-I' flags in + *note Scanner Options::) define the macro 'YY_INTERACTIVE'. If you + redefine 'LexerInput()' and need to take different actions + depending on whether or not the scanner might be scanning an + interactive input source, you can test for the presence of this + name via '#ifdef' statements. + +'virtual void LexerOutput( const char* buf, int size )' + writes out 'size' characters from the buffer 'buf', which, while + 'NUL'-terminated, may also contain internal 'NUL's if the scanner's + rules can match text with 'NUL's in them. + +'virtual void LexerError( const char* msg )' reports a fatal error message. The default version of this - function writes the message to the stream `cerr' and exits. + function writes the message to the stream 'cerr' and exits. - Note that a `yyFlexLexer' object contains its _entire_ scanning + Note that a 'yyFlexLexer' object contains its _entire_ scanning state. Thus you can use such objects to create reentrant scanners, but see also *note Reentrant::. You can instantiate multiple instances of -the same `yyFlexLexer' class, and you can also combine multiple C++ -scanner classes together in the same program using the `-P' option +the same 'yyFlexLexer' class, and you can also combine multiple C++ +scanner classes together in the same program using the '-P' option discussed above. - Finally, note that the `%array' feature is not available to C++ -scanner classes; you must use `%pointer' (the default). + Finally, note that the '%array' feature is not available to C++ +scanner classes; you must use '%pointer' (the default). Here is an example of a simple C++ scanner: @@ -3033,7 +3029,7 @@ scanner classes; you must use `%pointer' (the default). int mylineno = 0; %} - %option noyywrap + %option noyywrap c++ string \"[^\n"]+\" @@ -3078,6 +3074,9 @@ scanner classes; you must use `%pointer' (the default). %% + // This include is required if main() is an another source file. + //#include <FlexLexer.h> + int main( int /* argc */, char** /* argv */ ) { FlexLexer* lexer = new yyFlexLexer; @@ -3087,10 +3086,9 @@ scanner classes; you must use `%pointer' (the default). } If you want to create multiple (different) lexer classes, you use the -`-P' flag (or the `prefix=' option) to rename each `yyFlexLexer' to -some other `xxFlexLexer'. You then can include `<FlexLexer.h>' in your -other sources once per lexer class, first renaming `yyFlexLexer' as -follows: +'-P' flag (or the 'prefix=' option) to rename each 'yyFlexLexer' to some +other 'xxFlexLexer'. You then can include '<FlexLexer.h>' in your other +sources once per lexer class, first renaming 'yyFlexLexer' as follows: #undef yyFlexLexer #define yyFlexLexer xxFlexLexer @@ -3100,8 +3098,8 @@ follows: #define yyFlexLexer zzFlexLexer #include <FlexLexer.h> - if, for example, you used `%option prefix="xx"' for one of your -scanners and `%option prefix="zz"' for the other. + if, for example, you used '%option prefix="xx"' for one of your +scanners and '%option prefix="zz"' for the other. File: flex.info, Node: Reentrant, Next: Lex and Posix, Prev: Cxx, Up: Top @@ -3109,21 +3107,21 @@ File: flex.info, Node: Reentrant, Next: Lex and Posix, Prev: Cxx, Up: Top 19 Reentrant C Scanners *********************** -`flex' has the ability to generate a reentrant C scanner. This is -accomplished by specifying `%option reentrant' (`-R') The generated +'flex' has the ability to generate a reentrant C scanner. This is +accomplished by specifying '%option reentrant' ('-R') The generated scanner is both portable, and safe to use in one or more separate threads of control. The most common use for reentrant scanners is from -within multi-threaded applications. Any thread may create and execute -a reentrant `flex' scanner without the need for synchronization with -other threads. +within multi-threaded applications. Any thread may create and execute a +reentrant 'flex' scanner without the need for synchronization with other +threads. * Menu: -* Reentrant Uses:: -* Reentrant Overview:: -* Reentrant Example:: -* Reentrant Detail:: -* Reentrant Functions:: +* Reentrant Uses:: +* Reentrant Overview:: +* Reentrant Example:: +* Reentrant Detail:: +* Reentrant Functions:: File: flex.info, Node: Reentrant Uses, Next: Reentrant Overview, Prev: Reentrant, Up: Reentrant @@ -3132,8 +3130,8 @@ File: flex.info, Node: Reentrant Uses, Next: Reentrant Overview, Prev: Reentr ================================ However, there are other uses for a reentrant scanner. For example, you -could scan two or more files simultaneously to implement a `diff' at -the token level (i.e., instead of at the character level): +could scan two or more files simultaneously to implement a 'diff' at the +token level (i.e., instead of at the character level): /* Example of maintaining more than one active scanner. */ @@ -3150,9 +3148,9 @@ the token level (i.e., instead of at the character level): Another use for a reentrant scanner is recursion. (Note that a recursive scanner can also be created using a non-reentrant scanner and -buffer states. *Note Multiple Input Buffers::.) +buffer states. *Note Multiple Input Buffers::.) - The following crude scanner supports the `eval' command by invoking + The following crude scanner supports the 'eval' command by invoking another instance of itself. /* Example of recursive invocation. */ @@ -3183,22 +3181,22 @@ File: flex.info, Node: Reentrant Overview, Next: Reentrant Example, Prev: Ree ===================================== The API for reentrant scanners is different than for non-reentrant -scanners. Here is a quick overview of the API: +scanners. Here is a quick overview of the API: - `%option reentrant' must be specified. + '%option reentrant' must be specified. - * All functions take one additional argument: `yyscanner' + * All functions take one additional argument: 'yyscanner' * All global variables are replaced by their macro equivalents. (We tell you this because it may be important to you during debugging.) - * `yylex_init' and `yylex_destroy' must be called before and after - `yylex', respectively. + * 'yylex_init' and 'yylex_destroy' must be called before and after + 'yylex', respectively. * Accessor methods (get/set functions) provide access to common - `flex' variables. + 'flex' variables. - * User-specific data can be stored in `yyextra'. + * User-specific data can be stored in 'yyextra'. File: flex.info, Node: Reentrant Example, Next: Reentrant Detail, Prev: Reentrant Overview, Up: Reentrant @@ -3206,7 +3204,7 @@ File: flex.info, Node: Reentrant Example, Next: Reentrant Detail, Prev: Reent 19.3 Reentrant Example ====================== -First, an example of a reentrant scanner: +First, an example of a reentrant scanner: /* This scanner prints "//" comments. */ %option reentrant stack noyywrap @@ -3239,17 +3237,17 @@ File: flex.info, Node: Reentrant Detail, Next: Reentrant Functions, Prev: Ree ================================ Here are the things you need to do or know to use the reentrant C API of -`flex'. +'flex'. * Menu: -* Specify Reentrant:: -* Extra Reentrant Argument:: -* Global Replacement:: -* Init and Destroy Functions:: -* Accessor Methods:: -* Extra Data:: -* About yyscan_t:: +* Specify Reentrant:: +* Extra Reentrant Argument:: +* Global Replacement:: +* Init and Destroy Functions:: +* Accessor Methods:: +* Extra Data:: +* About yyscan_t:: File: flex.info, Node: Specify Reentrant, Next: Extra Reentrant Argument, Prev: Reentrant Detail, Up: Reentrant Detail @@ -3259,11 +3257,11 @@ File: flex.info, Node: Specify Reentrant, Next: Extra Reentrant Argument, Pre %option reentrant (-reentrant) must be specified. - Notice that `%option reentrant' is specified in the above example -(*note Reentrant Example::. Had this option not been specified, `flex' + Notice that '%option reentrant' is specified in the above example +(*note Reentrant Example::. Had this option not been specified, 'flex' would have happily generated a non-reentrant scanner without -complaining. You may explicitly specify `%option noreentrant', if you -do _not_ want a reentrant scanner, although it is not necessary. The +complaining. You may explicitly specify '%option noreentrant', if you +do _not_ want a reentrant scanner, although it is not necessary. The default is to generate a non-reentrant scanner. @@ -3272,25 +3270,25 @@ File: flex.info, Node: Extra Reentrant Argument, Next: Global Replacement, Pr 19.4.2 The Extra Argument ------------------------- -All functions take one additional argument: `yyscanner'. +All functions take one additional argument: 'yyscanner'. - Notice that the calls to `yy_push_state' and `yy_pop_state' both -have an argument, `yyscanner' , that is not present in a non-reentrant -scanner. Here are the declarations of `yy_push_state' and -`yy_pop_state' in the reentrant scanner: + Notice that the calls to 'yy_push_state' and 'yy_pop_state' both have +an argument, 'yyscanner' , that is not present in a non-reentrant +scanner. Here are the declarations of 'yy_push_state' and +'yy_pop_state' in the reentrant scanner: static void yy_push_state ( int new_state , yyscan_t yyscanner ) ; static void yy_pop_state ( yyscan_t yyscanner ) ; - Notice that the argument `yyscanner' appears in the declaration of -both functions. In fact, all `flex' functions in a reentrant scanner + Notice that the argument 'yyscanner' appears in the declaration of +both functions. In fact, all 'flex' functions in a reentrant scanner have this additional argument. It is always the last argument in the -argument list, it is always of type `yyscan_t' (which is typedef'd to -`void *') and it is always named `yyscanner'. As you may have guessed, -`yyscanner' is a pointer to an opaque data structure encapsulating the +argument list, it is always of type 'yyscan_t' (which is typedef'd to +'void *') and it is always named 'yyscanner'. As you may have guessed, +'yyscanner' is a pointer to an opaque data structure encapsulating the current state of the scanner. For a list of function declarations, see -*note Reentrant Functions::. Note that preprocessor macros, such as -`BEGIN', `ECHO', and `REJECT', do not take this additional argument. +*note Reentrant Functions::. Note that preprocessor macros, such as +'BEGIN', 'ECHO', and 'REJECT', do not take this additional argument. File: flex.info, Node: Global Replacement, Next: Init and Destroy Functions, Prev: Extra Reentrant Argument, Up: Reentrant Detail @@ -3301,22 +3299,22 @@ File: flex.info, Node: Global Replacement, Next: Init and Destroy Functions, All global variables in traditional flex have been replaced by macro equivalents. - Note that in the above example, `yyout' and `yytext' are not plain -variables. These are macros that will expand to their equivalent lvalue. -All of the familiar `flex' globals have been replaced by their macro -equivalents. In particular, `yytext', `yyleng', `yylineno', `yyin', -`yyout', `yyextra', `yylval', and `yylloc' are macros. You may safely -use these macros in actions as if they were plain variables. We only -tell you this so you don't expect to link to these variables -externally. Currently, each macro expands to a member of an internal + Note that in the above example, 'yyout' and 'yytext' are not plain +variables. These are macros that will expand to their equivalent +lvalue. All of the familiar 'flex' globals have been replaced by their +macro equivalents. In particular, 'yytext', 'yyleng', 'yylineno', +'yyin', 'yyout', 'yyextra', 'yylval', and 'yylloc' are macros. You may +safely use these macros in actions as if they were plain variables. We +only tell you this so you don't expect to link to these variables +externally. Currently, each macro expands to a member of an internal struct, e.g., #define yytext (((struct yyguts_t*)yyscanner)->yytext_r) - One important thing to remember about `yytext' and friends is that -`yytext' is not a global variable in a reentrant scanner, you can not -access it directly from outside an action or from other functions. You -must use an accessor method, e.g., `yyget_text', to accomplish this. + One important thing to remember about 'yytext' and friends is that +'yytext' is not a global variable in a reentrant scanner, you can not +access it directly from outside an action or from other functions. You +must use an accessor method, e.g., 'yyget_text', to accomplish this. (See below). @@ -3325,45 +3323,44 @@ File: flex.info, Node: Init and Destroy Functions, Next: Accessor Methods, Pr 19.4.4 Init and Destroy Functions --------------------------------- -`yylex_init' and `yylex_destroy' must be called before and after -`yylex', respectively. +'yylex_init' and 'yylex_destroy' must be called before and after +'yylex', respectively. int yylex_init ( yyscan_t * ptr_yy_globals ) ; int yylex_init_extra ( YY_EXTRA_TYPE user_defined, yyscan_t * ptr_yy_globals ) ; int yylex ( yyscan_t yyscanner ) ; int yylex_destroy ( yyscan_t yyscanner ) ; - The function `yylex_init' must be called before calling any other -function. The argument to `yylex_init' is the address of an -uninitialized pointer to be filled in by `yylex_init', overwriting any -previous contents. The function `yylex_init_extra' may be used instead, -taking as its first argument a variable of type `YY_EXTRA_TYPE'. See + The function 'yylex_init' must be called before calling any other +function. The argument to 'yylex_init' is the address of an +uninitialized pointer to be filled in by 'yylex_init', overwriting any +previous contents. The function 'yylex_init_extra' may be used instead, +taking as its first argument a variable of type 'YY_EXTRA_TYPE'. See the section on yyextra, below, for more details. - The value stored in `ptr_yy_globals' should thereafter be passed to -`yylex' and `yylex_destroy'. Flex does not save the argument passed to -`yylex_init', so it is safe to pass the address of a local pointer to -`yylex_init' so long as it remains in scope for the duration of all -calls to the scanner, up to and including the call to `yylex_destroy'. + The value stored in 'ptr_yy_globals' should thereafter be passed to +'yylex' and 'yylex_destroy'. Flex does not save the argument passed to +'yylex_init', so it is safe to pass the address of a local pointer to +'yylex_init' so long as it remains in scope for the duration of all +calls to the scanner, up to and including the call to 'yylex_destroy'. - The function `yylex' should be familiar to you by now. The reentrant + The function 'yylex' should be familiar to you by now. The reentrant version takes one argument, which is the value returned (via an -argument) by `yylex_init'. Otherwise, it behaves the same as the -non-reentrant version of `yylex'. +argument) by 'yylex_init'. Otherwise, it behaves the same as the +non-reentrant version of 'yylex'. - Both `yylex_init' and `yylex_init_extra' returns 0 (zero) on success, + Both 'yylex_init' and 'yylex_init_extra' returns 0 (zero) on success, or non-zero on failure, in which case errno is set to one of the following values: - * ENOMEM Memory allocation error. *Note memory-management::. - + * ENOMEM Memory allocation error. *Note memory-management::. * EINVAL Invalid argument. - The function `yylex_destroy' should be called to free resources used -by the scanner. After `yylex_destroy' is called, the contents of -`yyscanner' should not be used. Of course, there is no need to destroy -a scanner if you plan to reuse it. A `flex' scanner (both reentrant -and non-reentrant) may be restarted by calling `yyrestart'. + The function 'yylex_destroy' should be called to free resources used +by the scanner. After 'yylex_destroy' is called, the contents of +'yyscanner' should not be used. Of course, there is no need to destroy +a scanner if you plan to reuse it. A 'flex' scanner (both reentrant and +non-reentrant) may be restarted by calling 'yyrestart'. Below is an example of a program that creates a scanner, uses it, then destroys it when done: @@ -3388,17 +3385,17 @@ File: flex.info, Node: Accessor Methods, Next: Extra Data, Prev: Init and Des 19.4.5 Accessing Variables with Reentrant Scanners -------------------------------------------------- -Accessor methods (get/set functions) provide access to common `flex' +Accessor methods (get/set functions) provide access to common 'flex' variables. Many scanners that you build will be part of a larger project. -Portions of your project will need access to `flex' values, such as -`yytext'. In a non-reentrant scanner, these values are global, so -there is no problem accessing them. However, in a reentrant scanner, -there are no global `flex' values. You can not access them directly. -Instead, you must access `flex' values using accessor methods (get/set -functions). Each accessor method is named `yyget_NAME' or `yyset_NAME', -where `NAME' is the name of the `flex' variable you want. For example: +Portions of your project will need access to 'flex' values, such as +'yytext'. In a non-reentrant scanner, these values are global, so there +is no problem accessing them. However, in a reentrant scanner, there +are no global 'flex' values. You can not access them directly. +Instead, you must access 'flex' values using accessor methods (get/set +functions). Each accessor method is named 'yyget_NAME' or 'yyset_NAME', +where 'NAME' is the name of the 'flex' variable you want. For example: /* Set the last character of yytext to NULL. */ void chop ( yyscan_t scanner ) @@ -3412,8 +3409,8 @@ where `NAME' is the name of the `flex' variable you want. For example: %% .+\n { chop( yyscanner );} - You may find that `%option header-file' is particularly useful for -generating prototypes of all the accessor functions. *Note + You may find that '%option header-file' is particularly useful for +generating prototypes of all the accessor functions. *Note option-header::. @@ -3422,7 +3419,7 @@ File: flex.info, Node: Extra Data, Next: About yyscan_t, Prev: Accessor Metho 19.4.6 Extra Data ----------------- -User-specific data can be stored in `yyextra'. +User-specific data can be stored in 'yyextra'. In a reentrant scanner, it is unwise to use global variables to communicate with or maintain state between different pieces of your @@ -3430,23 +3427,23 @@ program. However, you may need access to external data or invoke external functions from within the scanner actions. Likewise, you may need to pass information to your scanner (e.g., open file descriptors, or database connections). In a non-reentrant scanner, the only way to -do this would be through the use of global variables. `Flex' allows -you to store arbitrary, "extra" data in a scanner. This data is -accessible through the accessor methods `yyget_extra' and `yyset_extra' -from outside the scanner, and through the shortcut macro `yyextra' from -within the scanner itself. They are defined as follows: +do this would be through the use of global variables. 'Flex' allows you +to store arbitrary, "extra" data in a scanner. This data is accessible +through the accessor methods 'yyget_extra' and 'yyset_extra' from +outside the scanner, and through the shortcut macro 'yyextra' from +within the scanner itself. They are defined as follows: #define YY_EXTRA_TYPE void* YY_EXTRA_TYPE yyget_extra ( yyscan_t scanner ); void yyset_extra ( YY_EXTRA_TYPE arbitrary_data , yyscan_t scanner); - In addition, an extra form of `yylex_init' is provided, -`yylex_init_extra'. This function is provided so that the yyextra value -can be accessed from within the very first yyalloc, used to allocate -the scanner itself. + In addition, an extra form of 'yylex_init' is provided, +'yylex_init_extra'. This function is provided so that the yyextra value +can be accessed from within the very first yyalloc, used to allocate the +scanner itself. - By default, `YY_EXTRA_TYPE' is defined as type `void *'. You may -redefine this type using `%option extra-type="your_type"' in the + By default, 'YY_EXTRA_TYPE' is defined as type 'void *'. You may +redefine this type using '%option extra-type="your_type"' in the scanner: /* An example of overriding YY_EXTRA_TYPE. */ @@ -3484,13 +3481,13 @@ File: flex.info, Node: About yyscan_t, Prev: Extra Data, Up: Reentrant Detail 19.4.7 About yyscan_t --------------------- -`yyscan_t' is defined as: +'yyscan_t' is defined as: typedef void* yyscan_t; - It is initialized by `yylex_init()' to point to an internal -structure. You should never access this value directly. In particular, -you should never attempt to free it (use `yylex_destroy()' instead.) + It is initialized by 'yylex_init()' to point to an internal +structure. You should never access this value directly. In particular, +you should never attempt to free it (use 'yylex_destroy()' instead.) File: flex.info, Node: Reentrant Functions, Prev: Reentrant Detail, Up: Reentrant @@ -3514,7 +3511,7 @@ The following Functions are available in a reentrant scanner: void yyset_lineno ( int line_number , yyscan_t scanner ); void yyset_extra ( YY_EXTRA_TYPE user_defined , yyscan_t scanner ); - There are no "set" functions for yytext and yyleng. This is + There are no "set" functions for yytext and yyleng. This is intentional. The following Macro shortcuts are available in actions in a reentrant @@ -3530,27 +3527,27 @@ scanner: In a reentrant C scanner, support for yylineno is always present (i.e., you may access yylineno), but the value is never modified by -`flex' unless `%option yylineno' is enabled. This is to allow the user -to maintain the line count independently of `flex'. +'flex' unless '%option yylineno' is enabled. This is to allow the user +to maintain the line count independently of 'flex'. - The following functions and macros are made available when `%option -bison-bridge' (`--bison-bridge') is specified: + The following functions and macros are made available when '%option +bison-bridge' ('--bison-bridge') is specified: YYSTYPE * yyget_lval ( yyscan_t scanner ); void yyset_lval ( YYSTYPE * yylvalp , yyscan_t scanner ); yylval - The following functions and macros are made available when `%option -bison-locations' (`--bison-locations') is specified: + The following functions and macros are made available when '%option +bison-locations' ('--bison-locations') is specified: YYLTYPE *yyget_lloc ( yyscan_t scanner ); void yyset_lloc ( YYLTYPE * yyllocp , yyscan_t scanner ); yylloc - Support for yylval assumes that `YYSTYPE' is a valid type. Support -for yylloc assumes that `YYSLYPE' is a valid type. Typically, these -types are generated by `bison', and are included in section 1 of the -`flex' input. + Support for yylval assumes that 'YYSTYPE' is a valid type. Support +for yylloc assumes that 'YYSLYPE' is a valid type. Typically, these +types are generated by 'bison', and are included in section 1 of the +'flex' input. File: flex.info, Node: Lex and Posix, Next: Memory Management, Prev: Reentrant, Up: Top @@ -3558,46 +3555,46 @@ File: flex.info, Node: Lex and Posix, Next: Memory Management, Prev: Reentran 20 Incompatibilities with Lex and Posix *************************************** -`flex' is a rewrite of the AT&T Unix _lex_ tool (the two -implementations do not share any code, though), with some extensions and +'flex' is a rewrite of the AT&T Unix _lex_ tool (the two implementations +do not share any code, though), with some extensions and incompatibilities, both of which are of concern to those who wish to -write scanners acceptable to both implementations. `flex' is fully -compliant with the POSIX `lex' specification, except that when using -`%pointer' (the default), a call to `unput()' destroys the contents of -`yytext', which is counter to the POSIX specification. In this section -we discuss all of the known areas of incompatibility between `flex', -AT&T `lex', and the POSIX specification. `flex''s `-l' option turns on -maximum compatibility with the original AT&T `lex' implementation, at +write scanners acceptable to both implementations. 'flex' is fully +compliant with the POSIX 'lex' specification, except that when using +'%pointer' (the default), a call to 'unput()' destroys the contents of +'yytext', which is counter to the POSIX specification. In this section +we discuss all of the known areas of incompatibility between 'flex', +AT&T 'lex', and the POSIX specification. 'flex''s '-l' option turns on +maximum compatibility with the original AT&T 'lex' implementation, at the cost of a major loss in the generated scanner's performance. We -note below which incompatibilities can be overcome using the `-l' -option. `flex' is fully compatible with `lex' with the following +note below which incompatibilities can be overcome using the '-l' +option. 'flex' is fully compatible with 'lex' with the following exceptions: - * The undocumented `lex' scanner internal variable `yylineno' is not - supported unless `-l' or `%option yylineno' is used. + * The undocumented 'lex' scanner internal variable 'yylineno' is not + supported unless '-l' or '%option yylineno' is used. - * `yylineno' should be maintained on a per-buffer basis, rather than + * 'yylineno' should be maintained on a per-buffer basis, rather than a per-scanner (single global variable) basis. - * `yylineno' is not part of the POSIX specification. + * 'yylineno' is not part of the POSIX specification. - * The `input()' routine is not redefinable, though it may be called + * The 'input()' routine is not redefinable, though it may be called to read characters following whatever has been matched by a rule. - If `input()' encounters an end-of-file the normal `yywrap()' - processing is done. A "real" end-of-file is returned by `input()' - as `EOF'. + If 'input()' encounters an end-of-file the normal 'yywrap()' + processing is done. A "real" end-of-file is returned by 'input()' + as 'EOF'. - * Input is instead controlled by defining the `YY_INPUT()' macro. + * Input is instead controlled by defining the 'YY_INPUT()' macro. - * The `flex' restriction that `input()' cannot be redefined is in + * The 'flex' restriction that 'input()' cannot be redefined is in accordance with the POSIX specification, which simply does not specify any way of controlling the scanner's input other than by - making an initial assignment to `yyin'. + making an initial assignment to 'yyin'. - * The `unput()' routine is not redefinable. This restriction is in + * The 'unput()' routine is not redefinable. This restriction is in accordance with POSIX. - * `flex' scanners are not as reentrant as `lex' scanners. In + * 'flex' scanners are not as reentrant as 'lex' scanners. In particular, if you have an interactive scanner and an interrupt handler which long-jumps out of the scanner, and the scanner is subsequently called again, you may get the following message: @@ -3609,139 +3606,118 @@ exceptions: yyrestart( yyin ); Note that this call will throw away any buffered input; usually - this isn't a problem with an interactive scanner. *Note - Reentrant::, for `flex''s reentrant API. + this isn't a problem with an interactive scanner. *Note + Reentrant::, for 'flex''s reentrant API. - * Also note that `flex' C++ scanner classes _are_ reentrant, so if - using C++ is an option for you, you should use them instead. - *Note Cxx::, and *note Reentrant:: for details. + * Also note that 'flex' C++ scanner classes _are_ reentrant, so if + using C++ is an option for you, you should use them instead. *Note + Cxx::, and *note Reentrant:: for details. - * `output()' is not supported. Output from the ECHO macro is done - to the file-pointer `yyout' (default `stdout)'. + * 'output()' is not supported. Output from the ECHO macro is done to + the file-pointer 'yyout' (default 'stdout)'. - * `output()' is not part of the POSIX specification. + * 'output()' is not part of the POSIX specification. - * `lex' does not support exclusive start conditions (%x), though they + * 'lex' does not support exclusive start conditions (%x), though they are in the POSIX specification. - * When definitions are expanded, `flex' encloses them in parentheses. - With `lex', the following: + * When definitions are expanded, 'flex' encloses them in parentheses. + With 'lex', the following: NAME [A-Z][A-Z0-9]* %% foo{NAME}? printf( "Found it\n" ); %% - will not match the string `foo' because when the macro is expanded - the rule is equivalent to `foo[A-Z][A-Z0-9]*?' and the precedence - is such that the `?' is associated with `[A-Z0-9]*'. With `flex', - the rule will be expanded to `foo([A-Z][A-Z0-9]*)?' and so the - string `foo' will match. + will not match the string 'foo' because when the macro is expanded + the rule is equivalent to 'foo[A-Z][A-Z0-9]*?' and the precedence + is such that the '?' is associated with '[A-Z0-9]*'. With 'flex', + the rule will be expanded to 'foo([A-Z][A-Z0-9]*)?' and so the + string 'foo' will match. - * Note that if the definition begins with `^' or ends with `$' then + * Note that if the definition begins with '^' or ends with '$' then it is _not_ expanded with parentheses, to allow these operators to appear in definitions without losing their special meanings. But - the `<s>', `/', and `<<EOF>>' operators cannot be used in a `flex' + the '<s>', '/', and '<<EOF>>' operators cannot be used in a 'flex' definition. - * Using `-l' results in the `lex' behavior of no parentheses around + * Using '-l' results in the 'lex' behavior of no parentheses around the definition. * The POSIX specification is that the definition be enclosed in parentheses. - * Some implementations of `lex' allow a rule's action to begin on a + * Some implementations of 'lex' allow a rule's action to begin on a separate line, if the rule's pattern has trailing whitespace: %% foo|bar<space here> { foobar_action();} - `flex' does not support this feature. + 'flex' does not support this feature. - * The `lex' `%r' (generate a Ratfor scanner) option is not - supported. It is not part of the POSIX specification. + * The 'lex' '%r' (generate a Ratfor scanner) option is not supported. + It is not part of the POSIX specification. - * After a call to `unput()', _yytext_ is undefined until the next - token is matched, unless the scanner was built using `%array'. - This is not the case with `lex' or the POSIX specification. The - `-l' option does away with this incompatibility. + * After a call to 'unput()', _yytext_ is undefined until the next + token is matched, unless the scanner was built using '%array'. + This is not the case with 'lex' or the POSIX specification. The + '-l' option does away with this incompatibility. - * The precedence of the `{,}' (numeric range) operator is different. - The AT&T and POSIX specifications of `lex' interpret `abc{1,3}' as - match one, two, or three occurrences of `abc'", whereas `flex' - interprets it as "match `ab' followed by one, two, or three - occurrences of `c'". The `-l' and `--posix' options do away with + * The precedence of the '{,}' (numeric range) operator is different. + The AT&T and POSIX specifications of 'lex' interpret 'abc{1,3}' as + match one, two, or three occurrences of 'abc'", whereas 'flex' + interprets it as "match 'ab' followed by one, two, or three + occurrences of 'c'". The '-l' and '--posix' options do away with this incompatibility. - * The precedence of the `^' operator is different. `lex' interprets - `^foo|bar' as "match either 'foo' at the beginning of a line, or - 'bar' anywhere", whereas `flex' interprets it as "match either - `foo' or `bar' if they come at the beginning of a line". The + * The precedence of the '^' operator is different. 'lex' interprets + '^foo|bar' as "match either 'foo' at the beginning of a line, or + 'bar' anywhere", whereas 'flex' interprets it as "match either + 'foo' or 'bar' if they come at the beginning of a line". The latter is in agreement with the POSIX specification. - * The special table-size declarations such as `%a' supported by - `lex' are not required by `flex' scanners.. `flex' ignores them. - - * The name `FLEX_SCANNER' is `#define''d so scanners may be written - for use with either `flex' or `lex'. Scanners also include - `YY_FLEX_MAJOR_VERSION', `YY_FLEX_MINOR_VERSION' and - `YY_FLEX_SUBMINOR_VERSION' indicating which version of `flex' - generated the scanner. For example, for the 2.5.22 release, these - defines would be 2, 5 and 22 respectively. If the version of - `flex' being used is a beta version, then the symbol `FLEX_BETA' - is defined. - - * The symbols `[[' and `]]' in the code sections of the input may - conflict with the m4 delimiters. *Note M4 Dependency::. - - - The following `flex' features are not included in `lex' or the POSIX + * The special table-size declarations such as '%a' supported by 'lex' + are not required by 'flex' scanners.. 'flex' ignores them. + * The name 'FLEX_SCANNER' is '#define''d so scanners may be written + for use with either 'flex' or 'lex'. Scanners also include + 'YY_FLEX_MAJOR_VERSION', 'YY_FLEX_MINOR_VERSION' and + 'YY_FLEX_SUBMINOR_VERSION' indicating which version of 'flex' + generated the scanner. For example, for the 2.5.22 release, these + defines would be 2, 5 and 22 respectively. If the version of + 'flex' being used is a beta version, then the symbol 'FLEX_BETA' is + defined. + + * The symbols '[[' and ']]' in the code sections of the input may + conflict with the m4 delimiters. *Note M4 Dependency::. + + The following 'flex' features are not included in 'lex' or the POSIX specification: * C++ scanners - * %option - * start condition scopes - * start condition stacks - * interactive/non-interactive scanners - * yy_scan_string() and friends - * yyterminate() - * yy_set_interactive() - * yy_set_bol() - - * YY_AT_BOL() <<EOF>> - + * YY_AT_BOL() <<EOF>> * <*> - * YY_DECL - * YY_START - * YY_USER_ACTION - * YY_USER_INIT - * #line directives - * %{}'s around actions - * reentrant C API - * multiple actions on a line + * almost all of the 'flex' command-line options - * almost all of the `flex' command-line options - - The feature "multiple actions on a line" refers to the fact that -with `flex' you can put multiple actions on the same line, separated -with semi-colons, while with `lex', the following: + The feature "multiple actions on a line" refers to the fact that with +'flex' you can put multiple actions on the same line, separated with +semi-colons, while with 'lex', the following: foo handle_foo(); ++num_foos_seen; @@ -3749,7 +3725,7 @@ with semi-colons, while with `lex', the following: foo handle_foo(); - `flex' does not truncate the action. Actions that are not enclosed + 'flex' does not truncate the action. Actions that are not enclosed in braces are simply terminated at the end of the line. @@ -3763,9 +3739,9 @@ override the default behavior. * Menu: -* The Default Memory Management:: -* Overriding The Default Memory Management:: -* A Note About yytext And Memory:: +* The Default Memory Management:: +* Overriding The Default Memory Management:: +* A Note About yytext And Memory:: File: flex.info, Node: The Default Memory Management, Next: Overriding The Default Memory Management, Prev: Memory Management, Up: Memory Management @@ -3773,74 +3749,73 @@ File: flex.info, Node: The Default Memory Management, Next: Overriding The Def 21.1 The Default Memory Management ================================== -Flex allocates dynamic memory during initialization, and once in a -while from within a call to yylex(). Initialization takes place during -the first call to yylex(). Thereafter, flex may reallocate more memory -if it needs to enlarge a buffer. As of version 2.5.9 Flex will clean up -all memory when you call `yylex_destroy' *Note faq-memory-leak::. +Flex allocates dynamic memory during initialization, and once in a while +from within a call to yylex(). Initialization takes place during the +first call to yylex(). Thereafter, flex may reallocate more memory if +it needs to enlarge a buffer. As of version 2.5.9 Flex will clean up +all memory when you call 'yylex_destroy' *Note faq-memory-leak::. Flex allocates dynamic memory for four purposes, listed below (1) 16kB for the input buffer. Flex allocates memory for the character buffer used to perform pattern matching. Flex must read ahead from the input stream and - store it in a large character buffer. This buffer is typically - the largest chunk of dynamic memory flex consumes. This buffer - will grow if necessary, doubling the size each time. Flex frees - this memory when you call yylex_destroy(). The default size of - this buffer (16384 bytes) is almost always too large. The ideal - size for this buffer is the length of the longest token expected, - in bytes, plus a little more. Flex will allocate a few extra - bytes for housekeeping. Currently, to override the size of the - input buffer you must `#define YY_BUF_SIZE' to whatever number of - bytes you want. We don't plan to change this in the near future, - but we reserve the right to do so if we ever add a more robust - memory management API. + store it in a large character buffer. This buffer is typically the + largest chunk of dynamic memory flex consumes. This buffer will + grow if necessary, doubling the size each time. Flex frees this + memory when you call yylex_destroy(). The default size of this + buffer (16384 bytes) is almost always too large. The ideal size + for this buffer is the length of the longest token expected, in + bytes, plus a little more. Flex will allocate a few extra bytes + for housekeeping. Currently, to override the size of the input + buffer you must '#define YY_BUF_SIZE' to whatever number of bytes + you want. We don't plan to change this in the near future, but we + reserve the right to do so if we ever add a more robust memory + management API. 64kb for the REJECT state. This will only be allocated if you use REJECT. - The size is large enough to hold the same number of states as - characters in the input buffer. If you override the size of the - input buffer (via `YY_BUF_SIZE'), then you automatically override + The size is large enough to hold the same number of states as + characters in the input buffer. If you override the size of the + input buffer (via 'YY_BUF_SIZE'), then you automatically override the size of this buffer as well. 100 bytes for the start condition stack. - Flex allocates memory for the start condition stack. This is the + Flex allocates memory for the start condition stack. This is the stack used for pushing start states, i.e., with yy_push_state(). It will grow if necessary. Since the states are simply integers, this stack doesn't consume much memory. This stack is not present - if `%option stack' is not specified. You will rarely need to tune - this buffer. The ideal size for this stack is the maximum depth + if '%option stack' is not specified. You will rarely need to tune + this buffer. The ideal size for this stack is the maximum depth expected. The memory for this stack is automatically destroyed - when you call yylex_destroy(). *Note option-stack::. + when you call yylex_destroy(). *Note option-stack::. 40 bytes for each YY_BUFFER_STATE. Flex allocates memory for each YY_BUFFER_STATE. The buffer state - itself is about 40 bytes, plus an additional large character - buffer (described above.) The initial buffer state is created - during initialization, and with each call to yy_create_buffer(). - You can't tune the size of this, but you can tune the character - buffer as described above. Any buffer state that you explicitly - create by calling yy_create_buffer() is _NOT_ destroyed - automatically. You must call yy_delete_buffer() to free the - memory. The exception to this rule is that flex will delete the - current buffer automatically when you call yylex_destroy(). If you - delete the current buffer, be sure to set it to NULL. That way, - flex will not try to delete the buffer a second time (possibly - crashing your program!) At the time of this writing, flex does not - provide a growable stack for the buffer states. You have to - manage that yourself. *Note Multiple Input Buffers::. + itself is about 40 bytes, plus an additional large character buffer + (described above.) The initial buffer state is created during + initialization, and with each call to yy_create_buffer(). You + can't tune the size of this, but you can tune the character buffer + as described above. Any buffer state that you explicitly create by + calling yy_create_buffer() is _NOT_ destroyed automatically. You + must call yy_delete_buffer() to free the memory. The exception to + this rule is that flex will delete the current buffer automatically + when you call yylex_destroy(). If you delete the current buffer, + be sure to set it to NULL. That way, flex will not try to delete + the buffer a second time (possibly crashing your program!) At the + time of this writing, flex does not provide a growable stack for + the buffer states. You have to manage that yourself. *Note + Multiple Input Buffers::. 84 bytes for the reentrant scanner guts Flex allocates about 84 bytes for the reentrant scanner structure - when you call yylex_init(). It is destroyed when the user calls + when you call yylex_init(). It is destroyed when the user calls yylex_destroy(). - ---------- Footnotes ---------- (1) The quantities given here are approximate, and may vary due to -host architecture, compiler configuration, or due to future -enhancements to flex. +host architecture, compiler configuration, or due to future enhancements +to flex. File: flex.info, Node: Overriding The Default Memory Management, Next: A Note About yytext And Memory, Prev: The Default Memory Management, Up: Memory Management @@ -3848,10 +3823,10 @@ File: flex.info, Node: Overriding The Default Memory Management, Next: A Note 21.2 Overriding The Default Memory Management ============================================= -Flex calls the functions `yyalloc', `yyrealloc', and `yyfree' when it -needs to allocate or free memory. By default, these functions are -wrappers around the standard C functions, `malloc', `realloc', and -`free', respectively. You can override the default implementations by +Flex calls the functions 'yyalloc', 'yyrealloc', and 'yyfree' when it +needs to allocate or free memory. By default, these functions are +wrappers around the standard C functions, 'malloc', 'realloc', and +'free', respectively. You can override the default implementations by telling flex that you will provide your own implementations. To override the default implementations, you must do two things: @@ -3859,11 +3834,9 @@ telling flex that you will provide your own implementations. 1. Suppress the default implementations by specifying one or more of the following options: - * `%option noyyalloc' - - * `%option noyyrealloc' - - * `%option noyyfree'. + * '%option noyyalloc' + * '%option noyyrealloc' + * '%option noyyfree'. 2. Provide your own implementation of the following functions: (1) @@ -3877,12 +3850,10 @@ telling flex that you will provide your own implementations. void * yyrealloc (void * ptr, size_t bytes, void * yyscanner); void yyfree (void * ptr, void * yyscanner); - - In the following example, we will override all three memory -routines. We assume that there is a custom allocator with garbage -collection. In order to make this example interesting, we will use a -reentrant scanner, passing a pointer to the custom allocator through -`yyextra'. + In the following example, we will override all three memory routines. +We assume that there is a custom allocator with garbage collection. In +order to make this example interesting, we will use a reentrant scanner, +passing a pointer to the custom allocator through 'yyextra'. %{ #include "some_allocator.h" @@ -3893,8 +3864,10 @@ reentrant scanner, passing a pointer to the custom allocator through %option reentrant /* Initialize the allocator. */ + %{ #define YY_EXTRA_TYPE struct allocator* #define YY_USER_INIT yyextra = allocator_create(); + %} %% .|\n ; @@ -3913,11 +3886,12 @@ reentrant scanner, passing a pointer to the custom allocator through /* Do nothing -- we leave it to the garbage collector. */ } + ---------- Footnotes ---------- (1) It is not necessary to override all (or any) of the memory -management routines. You may, for example, override `yyrealloc', but -not `yyfree' or `yyalloc'. +management routines. You may, for example, override 'yyrealloc', but +not 'yyfree' or 'yyalloc'. File: flex.info, Node: A Note About yytext And Memory, Prev: Overriding The Default Memory Management, Up: Memory Management @@ -3925,24 +3899,24 @@ File: flex.info, Node: A Note About yytext And Memory, Prev: Overriding The De 21.3 A Note About yytext And Memory =================================== -When flex finds a match, `yytext' points to the first character of the -match in the input buffer. The string itself is part of the input -buffer, and is _NOT_ allocated separately. The value of yytext will be -overwritten the next time yylex() is called. In short, the value of +When flex finds a match, 'yytext' points to the first character of the +match in the input buffer. The string itself is part of the input +buffer, and is _NOT_ allocated separately. The value of yytext will be +overwritten the next time yylex() is called. In short, the value of yytext is only valid from within the matched rule's action. Often, you want the value of yytext to persist for later processing, -i.e., by a parser with non-zero lookahead. In order to preserve yytext, -you will have to copy it with strdup() or a similar function. But this +i.e., by a parser with non-zero lookahead. In order to preserve yytext, +you will have to copy it with strdup() or a similar function. But this introduces some headache because your parser is now responsible for -freeing the copy of yytext. If you use a yacc or bison parser, +freeing the copy of yytext. If you use a yacc or bison parser, (commonly used with flex), you will discover that the error recovery mechanisms can cause memory to be leaked. To prevent memory leaks from strdup'd yytext, you will have to track -the memory somehow. Our experience has shown that a garbage collection -mechanism or a pooled memory mechanism will save you a lot of grief -when writing parsers. +the memory somehow. Our experience has shown that a garbage collection +mechanism or a pooled memory mechanism will save you a lot of grief when +writing parsers. File: flex.info, Node: Serialized Tables, Next: Diagnostics, Prev: Memory Management, Up: Top @@ -3950,24 +3924,24 @@ File: flex.info, Node: Serialized Tables, Next: Diagnostics, Prev: Memory Man 22 Serialized Tables ******************** -A `flex' scanner has the ability to save the DFA tables to a file, and -load them at runtime when needed. The motivation for this feature is -to reduce the runtime memory footprint. Traditionally, these tables -have been compiled into the scanner as C arrays, and are sometimes -quite large. Since the tables are compiled into the scanner, the -memory used by the tables can never be freed. This is a waste of -memory, especially if an application uses several scanners, but none of -them at the same time. +A 'flex' scanner has the ability to save the DFA tables to a file, and +load them at runtime when needed. The motivation for this feature is to +reduce the runtime memory footprint. Traditionally, these tables have +been compiled into the scanner as C arrays, and are sometimes quite +large. Since the tables are compiled into the scanner, the memory used +by the tables can never be freed. This is a waste of memory, especially +if an application uses several scanners, but none of them at the same +time. The serialization feature allows the tables to be loaded at runtime, -before scanning begins. The tables may be discarded when scanning is +before scanning begins. The tables may be discarded when scanning is finished. * Menu: -* Creating Serialized Tables:: -* Loading and Unloading Serialized Tables:: -* Tables File Format:: +* Creating Serialized Tables:: +* Loading and Unloading Serialized Tables:: +* Tables File Format:: File: flex.info, Node: Creating Serialized Tables, Next: Loading and Unloading Serialized Tables, Prev: Serialized Tables, Up: Serialized Tables @@ -3982,29 +3956,29 @@ You may create a scanner with serialized tables by specifying: --tables-file=FILE These options instruct flex to save the DFA tables to the file FILE. -The tables will _not_ be embedded in the generated scanner. The scanner -will not function on its own. The scanner will be dependent upon the -serialized tables. You must load the tables from this file at runtime +The tables will _not_ be embedded in the generated scanner. The scanner +will not function on its own. The scanner will be dependent upon the +serialized tables. You must load the tables from this file at runtime before you can scan anything. - If you do not specify a filename to `--tables-file', the tables will -be saved to `lex.yy.tables', where `yy' is the appropriate prefix. + If you do not specify a filename to '--tables-file', the tables will +be saved to 'lex.yy.tables', where 'yy' is the appropriate prefix. If your project uses several different scanners, you can concatenate the serialized tables into one file, and flex will find the correct set -of tables, using the scanner prefix as part of the lookup key. An +of tables, using the scanner prefix as part of the lookup key. An example follows: $ flex --tables-file --prefix=cpp cpp.l $ flex --tables-file --prefix=c c.l $ cat lex.cpp.tables lex.c.tables > all.tables - The above example created two scanners, `cpp', and `c'. Since we did -not specify a filename, the tables were serialized to `lex.c.tables' and -`lex.cpp.tables', respectively. Then, we concatenated the two files -together into `all.tables', which we will distribute with our project. + The above example created two scanners, 'cpp', and 'c'. Since we did +not specify a filename, the tables were serialized to 'lex.c.tables' and +'lex.cpp.tables', respectively. Then, we concatenated the two files +together into 'all.tables', which we will distribute with our project. At runtime, we will open the file and tell flex to load the tables from -it. Flex will find the correct tables automatically. (See next +it. Flex will find the correct tables automatically. (See next section). @@ -4013,33 +3987,33 @@ File: flex.info, Node: Loading and Unloading Serialized Tables, Next: Tables F 22.2 Loading and Unloading Serialized Tables ============================================ -If you've built your scanner with `%option tables-file', then you must -load the scanner tables at runtime. This can be accomplished with the +If you've built your scanner with '%option tables-file', then you must +load the scanner tables at runtime. This can be accomplished with the following function: -- Function: int yytables_fload (FILE* FP [, yyscan_t SCANNER]) Locates scanner tables in the stream pointed to by FP and loads - them. Memory for the tables is allocated via `yyalloc'. You must - call this function before the first call to `yylex'. The argument + them. Memory for the tables is allocated via 'yyalloc'. You must + call this function before the first call to 'yylex'. The argument SCANNER only appears in the reentrant scanner. This function - returns `0' (zero) on success, or non-zero on error. + returns '0' (zero) on success, or non-zero on error. The loaded tables are *not* automatically destroyed (unloaded) when -you call `yylex_destroy'. The reason is that you may create several +you call 'yylex_destroy'. The reason is that you may create several scanners of the same type (in a reentrant scanner), each of which needs -access to these tables. To avoid a nasty memory leak, you must call -the following function: +access to these tables. To avoid a nasty memory leak, you must call the +following function: -- Function: int yytables_destroy ([yyscan_t SCANNER]) - Unloads the scanner tables. The tables must be loaded again before + Unloads the scanner tables. The tables must be loaded again before you can scan any more data. The argument SCANNER only appears in - the reentrant scanner. This function returns `0' (zero) on + the reentrant scanner. This function returns '0' (zero) on success, or non-zero on error. - *The functions `yytables_fload' and `yytables_destroy' are not -thread-safe.* You must ensure that these functions are called exactly + *The functions 'yytables_fload' and 'yytables_destroy' are not +thread-safe.* You must ensure that these functions are called exactly once (for each scanner type) in a threaded program, before any thread -calls `yylex'. After the tables are loaded, they are never written to, +calls 'yylex'. After the tables are loaded, they are never written to, and no thread protection is required thereafter - until you destroy them. @@ -4049,11 +4023,11 @@ File: flex.info, Node: Tables File Format, Prev: Loading and Unloading Seriali 22.3 Tables File Format ======================= -This section defines the file format of serialized `flex' tables. +This section defines the file format of serialized 'flex' tables. The tables format allows for one or more sets of tables to be -specified, where each set corresponds to a given scanner. Scanners are -indexed by name, as described below. The file format is as follows: +specified, where each set corresponds to a given scanner. Scanners are +indexed by name, as described below. The file format is as follows: TABLE SET 1 +-------------------------------+ @@ -4086,147 +4060,131 @@ indexed by name, as described below. The file format is as follows: TABLE SET N The above diagram shows that a complete set of tables consists of a -header followed by multiple individual tables. Furthermore, multiple +header followed by multiple individual tables. Furthermore, multiple complete sets may be present in the same file, each set with its own -header and tables. The sets are contiguous in the file. The only way to -know if another set follows is to check the next four bytes for the +header and tables. The sets are contiguous in the file. The only way +to know if another set follows is to check the next four bytes for the magic number (or check for EOF). The header and tables sections are -padded to 64-bit boundaries. Below we describe each field in detail. -This format does not specify how the scanner will expand the given -data, i.e., data may be serialized as int8, but expanded to an int32 -array at runtime. This is to reduce the size of the serialized data -where possible. Remember, _all integer values are in network byte -order_. +padded to 64-bit boundaries. Below we describe each field in detail. +This format does not specify how the scanner will expand the given data, +i.e., data may be serialized as int8, but expanded to an int32 array at +runtime. This is to reduce the size of the serialized data where +possible. Remember, _all integer values are in network byte order_. Fields of a table header: -`th_magic' +'th_magic' Magic number, always 0xF13C57B1. -`th_hsize' - Size of this entire header, in bytes, including all fields plus - any padding. +'th_hsize' + Size of this entire header, in bytes, including all fields plus any + padding. -`th_ssize' +'th_ssize' Size of this entire set, in bytes, including the header, all tables, plus any padding. -`th_flags' - Bit flags for this table set. Currently unused. +'th_flags' + Bit flags for this table set. Currently unused. -`th_version[]' - Flex version in NULL-terminated string format. e.g., `2.5.13a'. +'th_version[]' + Flex version in NULL-terminated string format. e.g., '2.5.13a'. This is the version of flex that was used to create the serialized tables. -`th_name[]' - Contains the name of this table set. The default is `yytables', - and is prefixed accordingly, e.g., `footables'. Must be +'th_name[]' + Contains the name of this table set. The default is 'yytables', + and is prefixed accordingly, e.g., 'footables'. Must be NULL-terminated. -`th_pad64[]' +'th_pad64[]' Zero or more NULL bytes, padding the entire header to the next 64-bit boundary as calculated from the beginning of the header. Fields of a table: -`td_id' - Specifies the table identifier. Possible values are: - `YYTD_ID_ACCEPT (0x01)' - `yy_accept' - - `YYTD_ID_BASE (0x02)' - `yy_base' - - `YYTD_ID_CHK (0x03)' - `yy_chk' - - `YYTD_ID_DEF (0x04)' - `yy_def' - - `YYTD_ID_EC (0x05)' - `yy_ec ' - - `YYTD_ID_META (0x06)' - `yy_meta' - - `YYTD_ID_NUL_TRANS (0x07)' - `yy_NUL_trans' - - `YYTD_ID_NXT (0x08)' - `yy_nxt'. This array may be two dimensional. See the - `td_hilen' field below. - - `YYTD_ID_RULE_CAN_MATCH_EOL (0x09)' - `yy_rule_can_match_eol' - - `YYTD_ID_START_STATE_LIST (0x0A)' - `yy_start_state_list'. This array is handled specially - because it is an array of pointers to structs. See the - `td_flags' field below. - - `YYTD_ID_TRANSITION (0x0B)' - `yy_transition'. This array is handled specially because it - is an array of structs. See the `td_lolen' field below. - - `YYTD_ID_ACCLIST (0x0C)' - `yy_acclist' - -`td_flags' - Bit flags describing how to interpret the data in `td_data'. The +'td_id' + Specifies the table identifier. Possible values are: + 'YYTD_ID_ACCEPT (0x01)' + 'yy_accept' + 'YYTD_ID_BASE (0x02)' + 'yy_base' + 'YYTD_ID_CHK (0x03)' + 'yy_chk' + 'YYTD_ID_DEF (0x04)' + 'yy_def' + 'YYTD_ID_EC (0x05)' + 'yy_ec ' + 'YYTD_ID_META (0x06)' + 'yy_meta' + 'YYTD_ID_NUL_TRANS (0x07)' + 'yy_NUL_trans' + 'YYTD_ID_NXT (0x08)' + 'yy_nxt'. This array may be two dimensional. See the + 'td_hilen' field below. + 'YYTD_ID_RULE_CAN_MATCH_EOL (0x09)' + 'yy_rule_can_match_eol' + 'YYTD_ID_START_STATE_LIST (0x0A)' + 'yy_start_state_list'. This array is handled specially + because it is an array of pointers to structs. See the + 'td_flags' field below. + 'YYTD_ID_TRANSITION (0x0B)' + 'yy_transition'. This array is handled specially because it + is an array of structs. See the 'td_lolen' field below. + 'YYTD_ID_ACCLIST (0x0C)' + 'yy_acclist' + +'td_flags' + Bit flags describing how to interpret the data in 'td_data'. The data arrays are one-dimensional by default, but may be two - dimensional as specified in the `td_hilen' field. + dimensional as specified in the 'td_hilen' field. - `YYTD_DATA8 (0x01)' + 'YYTD_DATA8 (0x01)' The data is serialized as an array of type int8. - - `YYTD_DATA16 (0x02)' + 'YYTD_DATA16 (0x02)' The data is serialized as an array of type int16. - - `YYTD_DATA32 (0x04)' + 'YYTD_DATA32 (0x04)' The data is serialized as an array of type int32. - - `YYTD_PTRANS (0x08)' + 'YYTD_PTRANS (0x08)' The data is a list of indexes of entries in the expanded - `yy_transition' array. Each index should be expanded to a - pointer to the corresponding entry in the `yy_transition' - array. We count on the fact that the `yy_transition' array + 'yy_transition' array. Each index should be expanded to a + pointer to the corresponding entry in the 'yy_transition' + array. We count on the fact that the 'yy_transition' array has already been seen. - - `YYTD_STRUCT (0x10)' + 'YYTD_STRUCT (0x10)' The data is a list of yy_trans_info structs, each of which - consists of two integers. There is no padding between struct + consists of two integers. There is no padding between struct elements or between structs. The type of each member is - determined by the `YYTD_DATA*' bits. + determined by the 'YYTD_DATA*' bits. -`td_hilen' - If `td_hilen' is non-zero, then the data is a two-dimensional - array. Otherwise, the data is a one-dimensional array. `td_hilen' +'td_hilen' + If 'td_hilen' is non-zero, then the data is a two-dimensional + array. Otherwise, the data is a one-dimensional array. 'td_hilen' contains the number of elements in the higher dimensional array, - and `td_lolen' contains the number of elements in the lowest + and 'td_lolen' contains the number of elements in the lowest dimension. - Conceptually, `td_data' is either `sometype td_data[td_lolen]', or - `sometype td_data[td_hilen][td_lolen]', where `sometype' is - specified by the `td_flags' field. It is possible for both - `td_lolen' and `td_hilen' to be zero, in which case `td_data' is a + Conceptually, 'td_data' is either 'sometype td_data[td_lolen]', or + 'sometype td_data[td_hilen][td_lolen]', where 'sometype' is + specified by the 'td_flags' field. It is possible for both + 'td_lolen' and 'td_hilen' to be zero, in which case 'td_data' is a zero length array, and no data is loaded, i.e., this table is - simply skipped. Flex does not currently generate tables of zero + simply skipped. Flex does not currently generate tables of zero length. -`td_lolen' - Specifies the number of elements in the lowest dimension array. If +'td_lolen' + Specifies the number of elements in the lowest dimension array. If this is a one-dimensional array, then it is simply the number of elements in this array. The element size is determined by the - `td_flags' field. + 'td_flags' field. -`td_data[]' - The table data. This array may be a one- or two-dimensional array, - of type `int8', `int16', `int32', `struct yy_trans_info', or - `struct yy_trans_info*', depending upon the values in the - `td_flags', `td_hilen', and `td_lolen' fields. +'td_data[]' + The table data. This array may be a one- or two-dimensional array, + of type 'int8', 'int16', 'int32', 'struct yy_trans_info', or + 'struct yy_trans_info*', depending upon the values in the + 'td_flags', 'td_hilen', and 'td_lolen' fields. -`td_pad64[]' +'td_pad64[]' Zero or more NULL bytes, padding the entire table to the next 64-bit boundary as calculated from the beginning of this table. @@ -4236,71 +4194,70 @@ File: flex.info, Node: Diagnostics, Next: Limitations, Prev: Serialized Table 23 Diagnostics ************** -The following is a list of `flex' diagnostic messages: +The following is a list of 'flex' diagnostic messages: - * `warning, rule cannot be matched' indicates that the given rule + * 'warning, rule cannot be matched' indicates that the given rule cannot be matched because it follows other rules that will always - match the same text as it. For example, in the following `foo' + match the same text as it. For example, in the following 'foo' cannot be matched because it comes after an identifier "catch-all" rule: [a-z]+ got_identifier(); foo got_foo(); - Using `REJECT' in a scanner suppresses this warning. + Using 'REJECT' in a scanner suppresses this warning. - * `warning, -s option given but default rule can be matched' means + * 'warning, -s option given but default rule can be matched' means that it is possible (perhaps only in a particular start condition) that the default rule (match any single character) is the only one - that will match a particular input. Since `-s' was given, + that will match a particular input. Since '-s' was given, presumably this is not intended. - * `reject_used_but_not_detected undefined' or - `yymore_used_but_not_detected undefined'. These errors can occur - at compile time. They indicate that the scanner uses `REJECT' or - `yymore()' but that `flex' failed to notice the fact, meaning that - `flex' scanned the first two sections looking for occurrences of + * 'reject_used_but_not_detected undefined' or + 'yymore_used_but_not_detected undefined'. These errors can occur + at compile time. They indicate that the scanner uses 'REJECT' or + 'yymore()' but that 'flex' failed to notice the fact, meaning that + 'flex' scanned the first two sections looking for occurrences of these actions and failed to find any, but somehow you snuck some in - (via a #include file, for example). Use `%option reject' or - `%option yymore' to indicate to `flex' that you really do use - these features. + (via a #include file, for example). Use '%option reject' or + '%option yymore' to indicate to 'flex' that you really do use these + features. - * `flex scanner jammed'. a scanner compiled with `-s' has + * 'flex scanner jammed'. a scanner compiled with '-s' has encountered an input string which wasn't matched by any of its rules. This error can also occur due to internal problems. - * `token too large, exceeds YYLMAX'. your scanner uses `%array' and - one of its rules matched a string longer than the `YYLMAX' - constant (8K bytes by default). You can increase the value by - #define'ing `YYLMAX' in the definitions section of your `flex' - input. + * 'token too large, exceeds YYLMAX'. your scanner uses '%array' and + one of its rules matched a string longer than the 'YYLMAX' constant + (8K bytes by default). You can increase the value by #define'ing + 'YYLMAX' in the definitions section of your 'flex' input. - * `scanner requires -8 flag to use the character 'x''. Your scanner - specification includes recognizing the 8-bit character `'x'' and + * 'scanner requires -8 flag to use the character 'x''. Your scanner + specification includes recognizing the 8-bit character ''x'' and you did not specify the -8 flag, and your scanner defaulted to - 7-bit because you used the `-Cf' or `-CF' table compression - options. See the discussion of the `-7' flag, *note Scanner + 7-bit because you used the '-Cf' or '-CF' table compression + options. See the discussion of the '-7' flag, *note Scanner Options::, for details. - * `flex scanner push-back overflow'. you used `unput()' to push back + * 'flex scanner push-back overflow'. you used 'unput()' to push back so much text that the scanner's buffer could not hold both the - pushed-back text and the current token in `yytext'. Ideally the + pushed-back text and the current token in 'yytext'. Ideally the scanner should dynamically resize the buffer in this case, but at present it does not. - * `input buffer overflow, can't enlarge buffer because scanner uses + * 'input buffer overflow, can't enlarge buffer because scanner uses REJECT'. the scanner was working on matching an extremely large token and needed to expand the input buffer. This doesn't work - with scanners that use `REJECT'. + with scanners that use 'REJECT'. - * `fatal flex scanner internal error--end of buffer missed'. This can - occur in a scanner which is reentered after a long-jump has jumped - out (or over) the scanner's activation frame. Before reentering - the scanner, use: + * 'fatal flex scanner internal error--end of buffer missed'. This + can occur in a scanner which is reentered after a long-jump has + jumped out (or over) the scanner's activation frame. Before + reentering the scanner, use: yyrestart( yyin ); or, as noted above, switch to using the C++ scanner class. - * `too many start conditions in <> construct!' you listed more start + * 'too many start conditions in <> construct!' you listed more start conditions in a <> construct than exist (so you must have listed at least one of them twice). @@ -4311,38 +4268,38 @@ File: flex.info, Node: Limitations, Next: Bibliography, Prev: Diagnostics, U ************** Some trailing context patterns cannot be properly matched and generate -warning messages (`dangerous trailing context'). These are patterns +warning messages ('dangerous trailing context'). 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 second part, such as 'zx*/xy*', where the 'x*' matches the 'x' at the beginning of the trailing context. (Note that the POSIX draft states that the text matched by such patterns is undefined.) For some trailing context rules, parts which are actually fixed-length are not recognized as such, leading to the abovementioned performance loss. In -particular, parts using `|' or `{n}' (such as `foo{3}') are always -considered variable-length. Combining trailing context with the -special `|' action can result in _fixed_ trailing context being turned -into the more expensive _variable_ trailing context. For example, in -the following: +particular, parts using '|' or '{n}' (such as 'foo{3}') are always +considered variable-length. Combining trailing context with the special +'|' action can result in _fixed_ trailing context being turned into the +more expensive _variable_ trailing context. For example, in the +following: %% abc | xyz/def - Use of `unput()' invalidates yytext and yyleng, unless the `%array' -directive or the `-l' option has been used. Pattern-matching of `NUL's + Use of 'unput()' invalidates yytext and yyleng, unless the '%array' +directive or the '-l' option has been used. Pattern-matching of 'NUL's is substantially slower than matching other characters. Dynamic resizing of the input buffer is slow, as it entails rescanning all the text matched so far by the current (generally huge) token. Due to both buffering of input and read-ahead, you cannot intermix calls to -`<stdio.h>' routines, such as, getchar(), with `flex' rules and expect -it to work. Call `input()' instead. The total table entries listed by -the `-v' flag excludes the number of table entries needed to determine +'<stdio.h>' routines, such as, getchar(), with 'flex' rules and expect +it to work. Call 'input()' instead. The total table entries listed by +the '-v' flag excludes the number of table entries needed to determine what rule has been matched. The number of entries is equal to the -number of DFA states if the scanner does not use `REJECT', and somewhat -greater than the number of states if it does. `REJECT' cannot be used -with the `-f' or `-F' options. +number of DFA states if the scanner does not use 'REJECT', and somewhat +greater than the number of states if it does. 'REJECT' cannot be used +with the '-f' or '-F' options. - The `flex' internal algorithms need documentation. + The 'flex' internal algorithms need documentation. File: flex.info, Node: Bibliography, Next: FAQ, Prev: Limitations, Up: Top @@ -4352,11 +4309,8 @@ File: flex.info, Node: Bibliography, Next: FAQ, Prev: Limitations, Up: Top You may wish to read more about the following programs: * lex - * yacc - * sed - * awk The following books may contain material of interest: @@ -4368,7 +4322,7 @@ Associates. Be sure to get the 2nd edition. Alfred Aho, Ravi Sethi and Jeffrey Ullman, _Compilers: Principles, Techniques and Tools_, Addison-Wesley (1986). Describes the -pattern-matching techniques used by `flex' (deterministic finite +pattern-matching techniques used by 'flex' (deterministic finite automata). @@ -4377,111 +4331,111 @@ File: flex.info, Node: FAQ, Next: Appendices, Prev: Bibliography, Up: Top FAQ *** -From time to time, the `flex' maintainer receives certain questions. +From time to time, the 'flex' maintainer receives certain questions. Rather than repeat answers to well-understood problems, we publish them here. * Menu: -* When was flex born?:: -* How do I expand backslash-escape sequences in C-style quoted strings?:: -* Why do flex scanners call fileno if it is not ANSI compatible?:: -* Does flex support recursive pattern definitions?:: -* How do I skip huge chunks of input (tens of megabytes) while using flex?:: -* Flex is not matching my patterns in the same order that I defined them.:: -* My actions are executing out of order or sometimes not at all.:: -* How can I have multiple input sources feed into the same scanner at the same time?:: -* Can I build nested parsers that work with the same input file?:: -* How can I match text only at the end of a file?:: -* How can I make REJECT cascade across start condition boundaries?:: -* Why cant I use fast or full tables with interactive mode?:: -* How much faster is -F or -f than -C?:: -* If I have a simple grammar cant I just parse it with flex?:: -* Why doesn't yyrestart() set the start state back to INITIAL?:: -* How can I match C-style comments?:: -* The period isn't working the way I expected.:: -* Can I get the flex manual in another format?:: -* Does there exist a "faster" NDFA->DFA algorithm?:: -* How does flex compile the DFA so quickly?:: -* How can I use more than 8192 rules?:: -* How do I abandon a file in the middle of a scan and switch to a new file?:: -* How do I execute code only during initialization (only before the first scan)?:: -* How do I execute code at termination?:: -* Where else can I find help?:: -* Can I include comments in the "rules" section of the file?:: -* I get an error about undefined yywrap().:: -* How can I change the matching pattern at run time?:: -* How can I expand macros in the input?:: -* How can I build a two-pass scanner?:: -* How do I match any string not matched in the preceding rules?:: -* I am trying to port code from AT&T lex that uses yysptr and yysbuf.:: -* Is there a way to make flex treat NULL like a regular character?:: -* Whenever flex can not match the input it says "flex scanner jammed".:: -* Why doesn't flex have non-greedy operators like perl does?:: -* Memory leak - 16386 bytes allocated by malloc.:: -* How do I track the byte offset for lseek()?:: -* How do I use my own I/O classes in a C++ scanner?:: -* How do I skip as many chars as possible?:: -* deleteme00:: -* Are certain equivalent patterns faster than others?:: -* Is backing up a big deal?:: -* Can I fake multi-byte character support?:: -* deleteme01:: -* Can you discuss some flex internals?:: -* unput() messes up yy_at_bol:: -* The | operator is not doing what I want:: -* Why can't flex understand this variable trailing context pattern?:: -* The ^ operator isn't working:: -* Trailing context is getting confused with trailing optional patterns:: -* Is flex GNU or not?:: -* ERASEME53:: -* I need to scan if-then-else blocks and while loops:: -* ERASEME55:: -* ERASEME56:: -* ERASEME57:: -* Is there a repository for flex scanners?:: -* How can I conditionally compile or preprocess my flex input file?:: -* Where can I find grammars for lex and yacc?:: -* I get an end-of-buffer message for each character scanned.:: -* unnamed-faq-62:: -* unnamed-faq-63:: -* unnamed-faq-64:: -* unnamed-faq-65:: -* unnamed-faq-66:: -* unnamed-faq-67:: -* unnamed-faq-68:: -* unnamed-faq-69:: -* unnamed-faq-70:: -* unnamed-faq-71:: -* unnamed-faq-72:: -* unnamed-faq-73:: -* unnamed-faq-74:: -* unnamed-faq-75:: -* unnamed-faq-76:: -* unnamed-faq-77:: -* unnamed-faq-78:: -* unnamed-faq-79:: -* unnamed-faq-80:: -* unnamed-faq-81:: -* unnamed-faq-82:: -* unnamed-faq-83:: -* unnamed-faq-84:: -* unnamed-faq-85:: -* unnamed-faq-86:: -* unnamed-faq-87:: -* unnamed-faq-88:: -* unnamed-faq-90:: -* unnamed-faq-91:: -* unnamed-faq-92:: -* unnamed-faq-93:: -* unnamed-faq-94:: -* unnamed-faq-95:: -* unnamed-faq-96:: -* unnamed-faq-97:: -* unnamed-faq-98:: -* unnamed-faq-99:: -* unnamed-faq-100:: -* unnamed-faq-101:: +* When was flex born?:: +* How do I expand backslash-escape sequences in C-style quoted strings?:: +* Why do flex scanners call fileno if it is not ANSI compatible?:: +* Does flex support recursive pattern definitions?:: +* How do I skip huge chunks of input (tens of megabytes) while using flex?:: +* Flex is not matching my patterns in the same order that I defined them.:: +* My actions are executing out of order or sometimes not at all.:: +* How can I have multiple input sources feed into the same scanner at the same time?:: +* Can I build nested parsers that work with the same input file?:: +* How can I match text only at the end of a file?:: +* How can I make REJECT cascade across start condition boundaries?:: +* Why cant I use fast or full tables with interactive mode?:: +* How much faster is -F or -f than -C?:: +* If I have a simple grammar cant I just parse it with flex?:: +* Why doesn't yyrestart() set the start state back to INITIAL?:: +* How can I match C-style comments?:: +* The period isn't working the way I expected.:: +* Can I get the flex manual in another format?:: +* Does there exist a "faster" NDFA->DFA algorithm?:: +* How does flex compile the DFA so quickly?:: +* How can I use more than 8192 rules?:: +* How do I abandon a file in the middle of a scan and switch to a new file?:: +* How do I execute code only during initialization (only before the first scan)?:: +* How do I execute code at termination?:: +* Where else can I find help?:: +* Can I include comments in the "rules" section of the file?:: +* I get an error about undefined yywrap().:: +* How can I change the matching pattern at run time?:: +* How can I expand macros in the input?:: +* How can I build a two-pass scanner?:: +* How do I match any string not matched in the preceding rules?:: +* I am trying to port code from AT&T lex that uses yysptr and yysbuf.:: +* Is there a way to make flex treat NULL like a regular character?:: +* Whenever flex can not match the input it says "flex scanner jammed".:: +* Why doesn't flex have non-greedy operators like perl does?:: +* Memory leak - 16386 bytes allocated by malloc.:: +* How do I track the byte offset for lseek()?:: +* How do I use my own I/O classes in a C++ scanner?:: +* How do I skip as many chars as possible?:: +* deleteme00:: +* Are certain equivalent patterns faster than others?:: +* Is backing up a big deal?:: +* Can I fake multi-byte character support?:: +* deleteme01:: +* Can you discuss some flex internals?:: +* unput() messes up yy_at_bol:: +* The | operator is not doing what I want:: +* Why can't flex understand this variable trailing context pattern?:: +* The ^ operator isn't working:: +* Trailing context is getting confused with trailing optional patterns:: +* Is flex GNU or not?:: +* ERASEME53:: +* I need to scan if-then-else blocks and while loops:: +* ERASEME55:: +* ERASEME56:: +* ERASEME57:: +* Is there a repository for flex scanners?:: +* How can I conditionally compile or preprocess my flex input file?:: +* Where can I find grammars for lex and yacc?:: +* I get an end-of-buffer message for each character scanned.:: +* unnamed-faq-62:: +* unnamed-faq-63:: +* unnamed-faq-64:: +* unnamed-faq-65:: +* unnamed-faq-66:: +* unnamed-faq-67:: +* unnamed-faq-68:: +* unnamed-faq-69:: +* unnamed-faq-70:: +* unnamed-faq-71:: +* unnamed-faq-72:: +* unnamed-faq-73:: +* unnamed-faq-74:: +* unnamed-faq-75:: +* unnamed-faq-76:: +* unnamed-faq-77:: +* unnamed-faq-78:: +* unnamed-faq-79:: +* unnamed-faq-80:: +* unnamed-faq-81:: +* unnamed-faq-82:: +* unnamed-faq-83:: +* unnamed-faq-84:: +* unnamed-faq-85:: +* unnamed-faq-86:: +* unnamed-faq-87:: +* unnamed-faq-88:: +* unnamed-faq-90:: +* unnamed-faq-91:: +* unnamed-faq-92:: +* unnamed-faq-93:: +* unnamed-faq-94:: +* unnamed-faq-95:: +* unnamed-faq-96:: +* unnamed-faq-97:: +* unnamed-faq-98:: +* unnamed-faq-99:: +* unnamed-faq-100:: +* unnamed-faq-101:: * What is the difference between YYLEX_PARAM and YY_DECL?:: * Why do I get "conflicting types for yylex" error?:: * How do I access the values set in a Flex action from within a Bison action?:: @@ -4492,9 +4446,9 @@ File: flex.info, Node: When was flex born?, Next: How do I expand backslash-es When was flex born? =================== -Vern Paxson took over the `Software Tools' lex project from Jef -Poskanzer in 1982. At that point it was written in Ratfor. Around -1987 or so, Paxson translated it into C, and a legend was born :-). +Vern Paxson took over the 'Software Tools' lex project from Jef +Poskanzer in 1982. At that point it was written in Ratfor. Around 1987 +or so, Paxson translated it into C, and a legend was born :-). File: flex.info, Node: How do I expand backslash-escape sequences in C-style quoted strings?, Next: Why do flex scanners call fileno if it is not ANSI compatible?, Prev: When was flex born?, Up: FAQ @@ -4504,19 +4458,19 @@ How do I expand backslash-escape sequences in C-style quoted strings? A key point when scanning quoted strings is that you cannot (easily) write a single rule that will precisely match the string if you allow -things like embedded escape sequences and newlines. If you try to -match strings with a single rule then you'll wind up having to rescan -the string anyway to find any escape sequences. +things like embedded escape sequences and newlines. If you try to match +strings with a single rule then you'll wind up having to rescan the +string anyway to find any escape sequences. Instead you can use exclusive start conditions and a set of rules, -one for matching non-escaped text, one for matching a single escape, -one for matching an embedded newline, and one for recognizing the end -of the string. Each of these rules is then faced with the question of -where to put its intermediary results. The best solution is for the -rules to append their local value of `yytext' to the end of a "string -literal" buffer. A rule like the escape-matcher will append to the -buffer the meaning of the escape sequence rather than the literal text -in `yytext'. In this way, `yytext' does not need to be modified at all. +one for matching non-escaped text, one for matching a single escape, one +for matching an embedded newline, and one for recognizing the end of the +string. Each of these rules is then faced with the question of where to +put its intermediary results. The best solution is for the rules to +append their local value of 'yytext' to the end of a "string literal" +buffer. A rule like the escape-matcher will append to the buffer the +meaning of the escape sequence rather than the literal text in 'yytext'. +In this way, 'yytext' does not need to be modified at all. File: flex.info, Node: Why do flex scanners call fileno if it is not ANSI compatible?, Next: Does flex support recursive pattern definitions?, Prev: How do I expand backslash-escape sequences in C-style quoted strings?, Up: FAQ @@ -4524,13 +4478,13 @@ File: flex.info, Node: Why do flex scanners call fileno if it is not ANSI compa Why do flex scanners call fileno if it is not ANSI compatible? ============================================================== -Flex scanners call `fileno()' in order to get the file descriptor -corresponding to `yyin'. The file descriptor may be passed to -`isatty()' or `read()', depending upon which `%options' you specified. -If your system does not have `fileno()' support, to get rid of the -`read()' call, do not specify `%option read'. To get rid of the -`isatty()' call, you must specify one of `%option always-interactive' or -`%option never-interactive'. +Flex scanners call 'fileno()' in order to get the file descriptor +corresponding to 'yyin'. The file descriptor may be passed to +'isatty()' or 'read()', depending upon which '%options' you specified. +If your system does not have 'fileno()' support, to get rid of the +'read()' call, do not specify '%option read'. To get rid of the +'isatty()' call, you must specify one of '%option always-interactive' or +'%option never-interactive'. File: flex.info, Node: Does flex support recursive pattern definitions?, Next: How do I skip huge chunks of input (tens of megabytes) while using flex?, Prev: Why do flex scanners call fileno if it is not ANSI compatible?, Up: FAQ @@ -4543,13 +4497,13 @@ e.g., %% block "{"({block}|{statement})*"}" - No. You cannot have recursive definitions. The pattern-matching + No. You cannot have recursive definitions. The pattern-matching power of regular expressions in general (and therefore flex scanners, too) is limited. In particular, regular expressions cannot "balance" parentheses to an arbitrary degree. For example, it's impossible to write a regular expression that matches all strings containing the same number of '{'s as '}'s. For more powerful pattern matching, you need a -parser, such as `GNU bison'. +parser, such as 'GNU bison'. File: flex.info, Node: How do I skip huge chunks of input (tens of megabytes) while using flex?, Next: Flex is not matching my patterns in the same order that I defined them., Prev: Does flex support recursive pattern definitions?, Up: FAQ @@ -4557,7 +4511,7 @@ File: flex.info, Node: How do I skip huge chunks of input (tens of megabytes) w How do I skip huge chunks of input (tens of megabytes) while using flex? ======================================================================== -Use `fseek()' (or `lseek()') to position yyin, then call `yyrestart()'. +Use 'fseek()' (or 'lseek()') to position yyin, then call 'yyrestart()'. File: flex.info, Node: Flex is not matching my patterns in the same order that I defined them., Next: My actions are executing out of order or sometimes not at all., Prev: How do I skip huge chunks of input (tens of megabytes) while using flex?, Up: FAQ @@ -4565,32 +4519,32 @@ File: flex.info, Node: Flex is not matching my patterns in the same order that Flex is not matching my patterns in the same order that I defined them. ======================================================================= -`flex' picks the rule that matches the most text (i.e., the longest -possible input string). This is because `flex' uses an entirely +'flex' picks the rule that matches the most text (i.e., the longest +possible input string). This is because 'flex' uses an entirely different matching technique ("deterministic finite automata") that actually does all of the matching simultaneously, in parallel. (Seems impossible, but it's actually a fairly simple technique once you understand the principles.) A side-effect of this parallel matching is that when the input -matches more than one rule, `flex' scanners pick the rule that matched -the _most_ text. This is explained further in the manual, in the +matches more than one rule, 'flex' scanners pick the rule that matched +the _most_ text. This is explained further in the manual, in the section *Note Matching::. - If you want `flex' to choose a shorter match, then you can work + If you want 'flex' to choose a shorter match, then you can work around this behavior by expanding your short rule to match more text, then put back the extra: data_.* yyless( 5 ); BEGIN BLOCKIDSTATE; Another fix would be to make the second rule active only during the -`<BLOCKIDSTATE>' start condition, and make that start condition -exclusive by declaring it with `%x' instead of `%s'. +'<BLOCKIDSTATE>' start condition, and make that start condition +exclusive by declaring it with '%x' instead of '%s'. A final fix is to change the input language so that the ambiguity for -`data_' is removed, by adding characters to it that don't match the -identifier rule, or by removing characters (such as `_') from the -identifier rule so it no longer matches `data_'. (Of course, you might +'data_' is removed, by adding characters to it that don't match the +identifier rule, or by removing characters (such as '_') from the +identifier rule so it no longer matches 'data_'. (Of course, you might also not have the option of changing the input language.) @@ -4599,7 +4553,7 @@ File: flex.info, Node: My actions are executing out of order or sometimes not a My actions are executing out of order or sometimes not at all. ============================================================== -Most likely, you have (in error) placed the opening `{' of the action +Most likely, you have (in error) placed the opening '{' of the action block on a different line than the rule, e.g., ^(foo|bar) @@ -4607,9 +4561,9 @@ block on a different line than the rule, e.g., } - `flex' requires that the opening `{' of an action associated with a -rule begin on the same line as does the rule. You need instead to -write your rules as follows: + 'flex' requires that the opening '{' of an action associated with a +rule begin on the same line as does the rule. You need instead to write +your rules as follows: ^(foo|bar) { // CORRECT! @@ -4622,36 +4576,34 @@ How can I have multiple input sources feed into the same scanner at the same tim ================================================================================== If ... - * your scanner is free of backtracking (verified using `flex''s `-b' + * your scanner is free of backtracking (verified using 'flex''s '-b' flag), - - * AND you run your scanner interactively (`-I' option; default - unless using special table compression options), - - * AND you feed it one character at a time by redefining `YY_INPUT' - to do so, + * AND you run your scanner interactively ('-I' option; default unless + using special table compression options), + * AND you feed it one character at a time by redefining 'YY_INPUT' to + do so, then every time it matches a token, it will have exhausted its input buffer (because the scanner is free of backtracking). This means you -can safely use `select()' at the point and only call `yylex()' for -another token if `select()' indicates there's data available. +can safely use 'select()' at the point and only call 'yylex()' for +another token if 'select()' indicates there's data available. - That is, move the `select()' out from the input function to a point -where it determines whether `yylex()' gets called for the next token. + That is, move the 'select()' out from the input function to a point +where it determines whether 'yylex()' gets called for the next token. With this approach, you will still have problems if your input can -arrive piecemeal; `select()' could inform you that the beginning of a -token is available, you call `yylex()' to get it, but it winds up +arrive piecemeal; 'select()' could inform you that the beginning of a +token is available, you call 'yylex()' to get it, but it winds up blocking waiting for the later characters in the token. - Here's another way: Move your input multiplexing inside of -`YY_INPUT'. That is, whenever `YY_INPUT' is called, it `select()''s to -see where input is available. If input is available for the scanner, -it reads and returns the next byte. If input is available from another + Here's another way: Move your input multiplexing inside of +'YY_INPUT'. That is, whenever 'YY_INPUT' is called, it 'select()''s to +see where input is available. If input is available for the scanner, it +reads and returns the next byte. If input is available from another source, it calls whatever function is responsible for reading from that source. (If no input is available, it blocks until some input is available.) I've used this technique in an interpreter I wrote that -both reads keyboard input using a `flex' scanner and IPC traffic from +both reads keyboard input using a 'flex' scanner and IPC traffic from sockets, and it works fine. @@ -4661,14 +4613,14 @@ Can I build nested parsers that work with the same input file? ============================================================== This is not going to work without some additional effort. The reason is -that `flex' block-buffers the input it reads from `yyin'. This means -that the "outermost" `yylex()', when called, will automatically slurp -up the first 8K of input available on yyin, and subsequent calls to -other `yylex()''s won't see that input. You might be tempted to work -around this problem by redefining `YY_INPUT' to only return a small -amount of text, but it turns out that that approach is quite difficult. -Instead, the best solution is to combine all of your scanners into one -large scanner, using a different exclusive start condition for each. +that 'flex' block-buffers the input it reads from 'yyin'. This means +that the "outermost" 'yylex()', when called, will automatically slurp up +the first 8K of input available on yyin, and subsequent calls to other +'yylex()''s won't see that input. You might be tempted to work around +this problem by redefining 'YY_INPUT' to only return a small amount of +text, but it turns out that that approach is quite difficult. Instead, +the best solution is to combine all of your scanners into one large +scanner, using a different exclusive start condition for each. File: flex.info, Node: How can I match text only at the end of a file?, Next: How can I make REJECT cascade across start condition boundaries?, Prev: Can I build nested parsers that work with the same input file?, Up: FAQ @@ -4679,9 +4631,9 @@ How can I match text only at the end of a file? There is no way to write a rule which is "match this text, but only if it comes at the end of the file". You can fake it, though, if you happen to have a character lying around that you don't allow in your -input. Then you redefine `YY_INPUT' to call your own routine which, if -it sees an `EOF', returns the magic character first (and remembers to -return a real `EOF' next time it's called). Then you could write: +input. Then you redefine 'YY_INPUT' to call your own routine which, if +it sees an 'EOF', returns the magic character first (and remembers to +return a real 'EOF' next time it's called). Then you could write: <COMMENT>(.|\n)*{EOF_CHAR} /* saw comment at EOF */ @@ -4691,9 +4643,9 @@ File: flex.info, Node: How can I make REJECT cascade across start condition bou How can I make REJECT cascade across start condition boundaries? ================================================================ -You can do this as follows. Suppose you have a start condition `A', and -after exhausting all of the possible matches in `<A>', you want to try -matches in `<INITIAL>'. Then you could use the following: +You can do this as follows. Suppose you have a start condition 'A', and +after exhausting all of the possible matches in '<A>', you want to try +matches in '<INITIAL>'. Then you could use the following: %x A %% @@ -4729,10 +4681,10 @@ end-of-token test is much simpler, basically a compare with 0, so no memory bus cycles. Since the test occurs in the innermost scanning loop, one would like to make it go as fast as possible. - Still, it seems reasonable to allow the user to choose to trade off -a bit of performance in this area to gain the corresponding -flexibility. There might be another reason, though, why fast scanners -don't support the interactive option. + Still, it seems reasonable to allow the user to choose to trade off a +bit of performance in this area to gain the corresponding flexibility. +There might be another reason, though, why fast scanners don't support +the interactive option. File: flex.info, Node: How much faster is -F or -f than -C?, Next: If I have a simple grammar cant I just parse it with flex?, Prev: Why cant I use fast or full tables with interactive mode?, Up: FAQ @@ -4748,7 +4700,7 @@ File: flex.info, Node: If I have a simple grammar cant I just parse it with fle If I have a simple grammar can't I just parse it with flex? =========================================================== -Is your grammar recursive? That's almost always a sign that you're +Is your grammar recursive? That's almost always a sign that you're better off using a parser/scanner rather than just trying to use a scanner alone. @@ -4759,8 +4711,8 @@ Why doesn't yyrestart() set the start state back to INITIAL? ============================================================ There are two reasons. The first is that there might be programs that -rely on the start state not changing across file changes. The second -is that beginning with `flex' version 2.4, use of `yyrestart()' is no +rely on the start state not changing across file changes. The second is +that beginning with 'flex' version 2.4, use of 'yyrestart()' is no longer required, so fixing the problem there doesn't solve the more general problem. @@ -4800,29 +4752,26 @@ File: flex.info, Node: The period isn't working the way I expected., Next: Can The '.' isn't working the way I expected. ========================================= -Here are some tips for using `.': +Here are some tips for using '.': * A common mistake is to place the grouping parenthesis AFTER an - operator, when you really meant to place the parenthesis BEFORE - the operator, e.g., you probably want this `(foo|bar)+' and NOT - this `(foo|bar+)'. - - The first pattern matches the words `foo' or `bar' any number of - times, e.g., it matches the text `barfoofoobarfoo'. The second - pattern matches a single instance of `foo' or a single instance of - `bar' followed by one or more `r's, e.g., it matches the text - `barrrr' . - - * A `.' inside `[]''s just means a literal`.' (period), and NOT "any + operator, when you really meant to place the parenthesis BEFORE the + operator, e.g., you probably want this '(foo|bar)+' and NOT this + '(foo|bar+)'. + + The first pattern matches the words 'foo' or 'bar' any number of + times, e.g., it matches the text 'barfoofoobarfoo'. The second + pattern matches a single instance of 'foo' or a single instance of + 'bar' followed by one or more 'r's, e.g., it matches the text + 'barrrr' . + * A '.' inside '[]''s just means a literal'.' (period), and NOT "any character except newline". - - * Remember that `.' matches any character EXCEPT `\n' (and `EOF'). - If you really want to match ANY character, including newlines, - then use `(.|\n)' Beware that the regex `(.|\n)+' will match your - entire input! - - * Finally, if you want to match a literal `.' (a period), then use - `[.]' or `"."' + * Remember that '.' matches any character EXCEPT '\n' (and 'EOF'). + If you really want to match ANY character, including newlines, then + use '(.|\n)' Beware that the regex '(.|\n)+' will match your entire + input! + * Finally, if you want to match a literal '.' (a period), then use + '[.]' or '"."' File: flex.info, Node: Can I get the flex manual in another format?, Next: Does there exist a "faster" NDFA->DFA algorithm?, Prev: The period isn't working the way I expected., Up: FAQ @@ -4830,8 +4779,8 @@ File: flex.info, Node: Can I get the flex manual in another format?, Next: Doe Can I get the flex manual in another format? ============================================ -The `flex' source distribution includes a texinfo manual. You are free -to convert that texinfo into whatever format you desire. The `texinfo' +The 'flex' source distribution includes a texinfo manual. You are free +to convert that texinfo into whatever format you desire. The 'texinfo' package includes tools for conversion to a number of formats. @@ -4851,7 +4800,7 @@ File: flex.info, Node: How does flex compile the DFA so quickly?, Next: How ca How does flex compile the DFA so quickly? ========================================= -There are two big speed wins that `flex' uses: +There are two big speed wins that 'flex' uses: 1. It analyzes the input rules to construct equivalence classes for those characters that always make the same transitions. It then @@ -4859,7 +4808,6 @@ There are two big speed wins that `flex' uses: of characters. This cuts down the NFA->DFA computation time dramatically, to the point where, for uncompressed DFA tables, the DFA generation is often I/O bound in writing out the tables. - 2. It maintains hash values for previously computed DFA states, so testing whether a newly constructed DFA state is equivalent to a previously constructed state can be done very quickly, by first @@ -4871,9 +4819,9 @@ File: flex.info, Node: How can I use more than 8192 rules?, Next: How do I aba How can I use more than 8192 rules? =================================== -`Flex' is compiled with an upper limit of 8192 rules per scanner. If +'Flex' is compiled with an upper limit of 8192 rules per scanner. If you need more than 8192 rules in your scanner, you'll have to recompile -`flex' with the following changes in `flexdef.h': +'flex' with the following changes in 'flexdef.h': < #define YY_TRAILING_MASK 0x2000 < #define YY_TRAILING_HEAD_MASK 0x4000 @@ -4906,9 +4854,9 @@ File: flex.info, Node: How do I abandon a file in the middle of a scan and swit How do I abandon a file in the middle of a scan and switch to a new file? ========================================================================= -Just call `yyrestart(newfile)'. Be sure to reset the start state if you -want a "fresh start, since `yyrestart' does NOT reset the start state -back to `INITIAL'. +Just call 'yyrestart(newfile)'. Be sure to reset the start state if you +want a "fresh start, since 'yyrestart' does NOT reset the start state +back to 'INITIAL'. File: flex.info, Node: How do I execute code only during initialization (only before the first scan)?, Next: How do I execute code at termination?, Prev: How do I abandon a file in the middle of a scan and switch to a new file?, Up: FAQ @@ -4916,9 +4864,9 @@ File: flex.info, Node: How do I execute code only during initialization (only b How do I execute code only during initialization (only before the first scan)? ============================================================================== -You can specify an initial action by defining the macro `YY_USER_INIT' -(though note that `yyout' may not be available at the time this macro -is executed). Or you can add to the beginning of your rules section: +You can specify an initial action by defining the macro 'YY_USER_INIT' +(though note that 'yyout' may not be available at the time this macro is +executed). Or you can add to the beginning of your rules section: %% /* Must be indented! */ @@ -4935,7 +4883,7 @@ File: flex.info, Node: How do I execute code at termination?, Next: Where else How do I execute code at termination? ===================================== -You can specify an action for the `<<EOF>>' rule. +You can specify an action for the '<<EOF>>' rule. File: flex.info, Node: Where else can I find help?, Next: Can I include comments in the "rules" section of the file?, Prev: How do I execute code at termination?, Up: FAQ @@ -4944,7 +4892,7 @@ Where else can I find help? =========================== You can find the flex homepage on the web at -`http://flex.sourceforge.net/'. See that page for details about flex +<http://flex.sourceforge.net/>. See that page for details about flex mailing lists as well. @@ -4953,7 +4901,7 @@ File: flex.info, Node: Can I include comments in the "rules" section of the fil Can I include comments in the "rules" section of the file? ========================================================== -Yes, just about anywhere you want to. See the manual for the specific +Yes, just about anywhere you want to. See the manual for the specific syntax. @@ -4962,12 +4910,12 @@ File: flex.info, Node: I get an error about undefined yywrap()., Next: How can I get an error about undefined yywrap(). ======================================== -You must supply a `yywrap()' function of your own, or link to `libfl.a' +You must supply a 'yywrap()' function of your own, or link to 'libfl.a' (which provides one), or use %option noyywrap - in your source to say you don't want a `yywrap()' function. + in your source to say you don't want a 'yywrap()' function. File: flex.info, Node: How can I change the matching pattern at run time?, Next: How can I expand macros in the input?, Prev: I get an error about undefined yywrap()., Up: FAQ @@ -4984,8 +4932,8 @@ File: flex.info, Node: How can I expand macros in the input?, Next: How can I How can I expand macros in the input? ===================================== -The best way to approach this problem is at a higher level, e.g., in -the parser. +The best way to approach this problem is at a higher level, e.g., in the +parser. However, you can do this using multiple input buffers. @@ -5020,13 +4968,13 @@ How can I build a two-pass scanner? =================================== One way to do it is to filter the first pass to a temporary file, then -process the temporary file on the second pass. You will probably see a +process the temporary file on the second pass. You will probably see a performance hit, due to all the disk I/O. When you need to look ahead far forward like this, it almost always means that the right solution is to build a parse tree of the entire -input, then walk it after the parse in order to generate the output. -In a sense, this is a two-pass approach, once through the text and once +input, then walk it after the parse in order to generate the output. In +a sense, this is a two-pass approach, once through the text and once through the parse tree, but the performance hit for the latter is usually an order of magnitude smaller, since everything is already classified, in binary format, and residing in memory. @@ -5037,18 +4985,18 @@ File: flex.info, Node: How do I match any string not matched in the preceding r How do I match any string not matched in the preceding rules? ============================================================= -One way to assign precedence, is to place the more specific rules -first. If two rules would match the same input (same sequence of -characters) then the first rule listed in the `flex' input wins, e.g., +One way to assign precedence, is to place the more specific rules first. +If two rules would match the same input (same sequence of characters) +then the first rule listed in the 'flex' input wins, e.g., %% foo[a-zA-Z_]+ return FOO_ID; bar[a-zA-Z_]+ return BAR_ID; [a-zA-Z_]+ return GENERIC_ID; - Note that the rule `[a-zA-Z_]+' must come *after* the others. It + Note that the rule '[a-zA-Z_]+' must come *after* the others. It will match the same amount of text as the more specific rules, and in -that case the `flex' scanner will pick the first rule listed in your +that case the 'flex' scanner will pick the first rule listed in your scanner as the one to match. @@ -5059,10 +5007,10 @@ I am trying to port code from AT&T lex that uses yysptr and yysbuf. Those are internal variables pointing into the AT&T scanner's input buffer. I imagine they're being manipulated in user versions of the -`input()' and `unput()' functions. If so, what you need to do is +'input()' and 'unput()' functions. If so, what you need to do is analyze those functions to figure out what they're doing, and then -replace `input()' with an appropriate definition of `YY_INPUT'. You -shouldn't need to (and must not) replace `flex''s `unput()' function. +replace 'input()' with an appropriate definition of 'YY_INPUT'. You +shouldn't need to (and must not) replace 'flex''s 'unput()' function. File: flex.info, Node: Is there a way to make flex treat NULL like a regular character?, Next: Whenever flex can not match the input it says "flex scanner jammed"., Prev: I am trying to port code from AT&T lex that uses yysptr and yysbuf., Up: FAQ @@ -5070,8 +5018,8 @@ File: flex.info, Node: Is there a way to make flex treat NULL like a regular ch Is there a way to make flex treat NULL like a regular character? ================================================================ -Yes, `\0' and `\x00' should both do the trick. Perhaps you have an -ancient version of `flex'. The latest release is version 2.5.39. +Yes, '\0' and '\x00' should both do the trick. Perhaps you have an +ancient version of 'flex'. The latest release is version 2.6.0. File: flex.info, Node: Whenever flex can not match the input it says "flex scanner jammed"., Next: Why doesn't flex have non-greedy operators like perl does?, Prev: Is there a way to make flex treat NULL like a regular character?, Up: FAQ @@ -5087,7 +5035,7 @@ You need to add a rule that matches the otherwise-unmatched text, e.g., . printf("bad input character '%s' at line %d\n", yytext, yylineno); - See `%option default' for more information. + See '%option default' for more information. File: flex.info, Node: Why doesn't flex have non-greedy operators like perl does?, Next: Memory leak - 16386 bytes allocated by malloc., Prev: Whenever flex can not match the input it says "flex scanner jammed"., Up: FAQ @@ -5108,9 +5056,9 @@ decent job. Better is to either introduce a separate parser, or to split the scanner into multiple scanners using (exclusive) start conditions. - You might have a separate start state once you've seen the `BEGIN'. -In that state, you might then have a regex that will match `END' (to -kick you out of the state), and perhaps `(.|\n)' to get a single + You might have a separate start state once you've seen the 'BEGIN'. +In that state, you might then have a regex that will match 'END' (to +kick you out of the state), and perhaps '(.|\n)' to get a single character within the chunk ... This approach also has much better error-reporting properties. @@ -5121,18 +5069,18 @@ File: flex.info, Node: Memory leak - 16386 bytes allocated by malloc., Next: H Memory leak - 16386 bytes allocated by malloc. ============================================== -UPDATED 2002-07-10: As of `flex' version 2.5.9, this leak means that -you did not call `yylex_destroy()'. If you are using an earlier version -of `flex', then read on. +UPDATED 2002-07-10: As of 'flex' version 2.5.9, this leak means that you +did not call 'yylex_destroy()'. If you are using an earlier version of +'flex', then read on. The leak is about 16426 bytes. That is, (8192 * 2 + 2) for the -read-buffer, and about 40 for `struct yy_buffer_state' (depending upon -alignment). The leak is in the non-reentrant C scanner only (NOT in the -reentrant scanner, NOT in the C++ scanner). Since `flex' doesn't know +read-buffer, and about 40 for 'struct yy_buffer_state' (depending upon +alignment). The leak is in the non-reentrant C scanner only (NOT in the +reentrant scanner, NOT in the C++ scanner). Since 'flex' doesn't know when you are done, the buffer is never freed. - However, the leak won't multiply since the buffer is reused no -matter how many times you call `yylex()'. + However, the leak won't multiply since the buffer is reused no matter +how many times you call 'yylex()'. If you want to reclaim the memory when you are completely done scanning, then you might try this: @@ -5141,8 +5089,8 @@ scanning, then you might try this: yy_delete_buffer(YY_CURRENT_BUFFER); yy_init = 1; - Note: `yy_init' is an "internal variable", and hasn't been tested in -this situation. It is possible that some other globals may need + Note: 'yy_init' is an "internal variable", and hasn't been tested in +this situation. It is possible that some other globals may need resetting as well. @@ -5157,24 +5105,24 @@ How do I track the byte offset for lseek()? > seek_position = (no_buffers)*YY_READ_BUF_SIZE + yy_c_buf_p - YY_CURRENT_BUFFER->yy_ch_buf While this is the right idea, it has two problems. The first is that -it's possible that `flex' will request less than `YY_READ_BUF_SIZE' -during an invocation of `YY_INPUT' (or that your input source will -return less even though `YY_READ_BUF_SIZE' bytes were requested). The -second problem is that when refilling its internal buffer, `flex' keeps +it's possible that 'flex' will request less than 'YY_READ_BUF_SIZE' +during an invocation of 'YY_INPUT' (or that your input source will +return less even though 'YY_READ_BUF_SIZE' bytes were requested). The +second problem is that when refilling its internal buffer, 'flex' keeps some characters from the previous buffer (because usually it's in the -middle of a match, and needs those characters to construct `yytext' for -the match once it's done). Because of this, `yy_c_buf_p - +middle of a match, and needs those characters to construct 'yytext' for +the match once it's done). Because of this, 'yy_c_buf_p - YY_CURRENT_BUFFER->yy_ch_buf' won't be exactly the number of characters already read from the current buffer. An alternative solution is to count the number of characters you've matched since starting to scan. This can be done by using -`YY_USER_ACTION'. For example, +'YY_USER_ACTION'. For example, #define YY_USER_ACTION num_chars += yyleng; (You need to be careful to update your bookkeeping if you use -`yymore('), `yyless()', `unput()', or `input()'.) +'yymore('), 'yyless()', 'unput()', or 'input()'.) File: flex.info, Node: How do I use my own I/O classes in a C++ scanner?, Next: How do I skip as many chars as possible?, Prev: How do I track the byte offset for lseek()?, Up: FAQ @@ -5182,16 +5130,16 @@ File: flex.info, Node: How do I use my own I/O classes in a C++ scanner?, Next How do I use my own I/O classes in a C++ scanner? ================================================= -When the flex C++ scanning class rewrite finally happens, then this -sort of thing should become much easier. +When the flex C++ scanning class rewrite finally happens, then this sort +of thing should become much easier. You can do this by passing the various functions (such as -`LexerInput()' and `LexerOutput()') NULL `iostream*''s, and then -dealing with your own I/O classes surreptitiously (i.e., stashing them -in special member variables). This works because the only assumption -about the lexer regarding what's done with the iostream's is that -they're ultimately passed to `LexerInput()' and `LexerOutput', which -then do whatever is necessary with them. +'LexerInput()' and 'LexerOutput()') NULL 'iostream*''s, and then dealing +with your own I/O classes surreptitiously (i.e., stashing them in +special member variables). This works because the only assumption about +the lexer regarding what's done with the iostream's is that they're +ultimately passed to 'LexerInput()' and 'LexerOutput', which then do +whatever is necessary with them. File: flex.info, Node: How do I skip as many chars as possible?, Next: deleteme00, Prev: How do I use my own I/O classes in a C++ scanner?, Up: FAQ @@ -5203,7 +5151,7 @@ How do I skip as many chars as possible - without interfering with the other patterns? In the example below, we want to skip over characters until we see -the phrase "endskip". The following will _NOT_ work correctly (do you +the phrase "endskip". The following will _NOT_ work correctly (do you see why not?) /* INCORRECT SCANNER */ @@ -5220,8 +5168,8 @@ The simplest (but slow) fix is: <SKIP>"endskip" BEGIN(INITIAL); <SKIP>. ; - The fix involves making the second rule match more, without making -it match "endskip" plus something else. So for example: + The fix involves making the second rule match more, without making it +match "endskip" plus something else. So for example: <SKIP>"endskip" BEGIN(INITIAL); <SKIP>[^e]+ ; @@ -5846,7 +5794,7 @@ File: flex.info, Node: Is there a repository for flex scanners?, Next: How can Is there a repository for flex scanners? ======================================== -Not that we know of. You might try asking on comp.compilers. +Not that we know of. You might try asking on comp.compilers. File: flex.info, Node: How can I conditionally compile or preprocess my flex input file?, Next: Where can I find grammars for lex and yacc?, Prev: Is there a repository for flex scanners?, Up: FAQ @@ -5873,8 +5821,8 @@ I get an end-of-buffer message for each character scanned. This will happen if your LexerInput() function returns only one character at a time, which can happen either if you're scanner is -"interactive", or if the streams library on your platform always -returns 1 for yyin->gcount(). +"interactive", or if the streams library on your platform always returns +1 for yyin->gcount(). Solution: override LexerInput() with a version that returns whole buffers. @@ -7082,10 +7030,10 @@ File: flex.info, Node: What is the difference between YYLEX_PARAM and YY_DECL?, What is the difference between YYLEX_PARAM and YY_DECL? ======================================================= -YYLEX_PARAM is not a flex symbol. It is for Bison. It tells Bison to +YYLEX_PARAM is not a flex symbol. It is for Bison. It tells Bison to pass extra params when it calls yylex() from the parser. - YY_DECL is the Flex declaration of yylex. The default is similar to + YY_DECL is the Flex declaration of yylex. The default is similar to this: #define int yy_lex () @@ -7106,8 +7054,8 @@ File: flex.info, Node: How do I access the values set in a Flex action from wit How do I access the values set in a Flex action from within a Bison action? =========================================================================== -With $1, $2, $3, etc. These are called "Semantic Values" in the Bison -manual. See *note Top: (bison)Top. +With $1, $2, $3, etc. These are called "Semantic Values" in the Bison +manual. See *note (bison)Top::. File: flex.info, Node: Appendices, Next: Indices, Prev: FAQ, Up: Top @@ -7117,10 +7065,10 @@ Appendix A Appendices * Menu: -* Makefiles and Flex:: -* Bison Bridge:: -* M4 Dependency:: -* Common Patterns:: +* Makefiles and Flex:: +* Bison Bridge:: +* M4 Dependency:: +* Common Patterns:: File: flex.info, Node: Makefiles and Flex, Next: Bison Bridge, Prev: Appendices, Up: Appendices @@ -7131,17 +7079,17 @@ A.1 Makefiles and Flex In this appendix, we provide tips for writing Makefiles to build your scanners. - In a traditional build environment, we say that the `.c' files are -the sources, and the `.o' files are the intermediate files. When using -`flex', however, the `.l' files are the sources, and the generated `.c' -files (along with the `.o' files) are the intermediate files. This + In a traditional build environment, we say that the '.c' files are +the sources, and the '.o' files are the intermediate files. When using +'flex', however, the '.l' files are the sources, and the generated '.c' +files (along with the '.o' files) are the intermediate files. This requires you to carefully plan your Makefile. - Modern `make' programs understand that `foo.l' is intended to -generate `lex.yy.c' or `foo.c', and will behave accordingly(1)(2). The -following Makefile does not explicitly instruct `make' how to build -`foo.c' from `foo.l'. Instead, it relies on the implicit rules of the -`make' program to build the intermediate file, `scan.c': + Modern 'make' programs understand that 'foo.l' is intended to +generate 'lex.yy.c' or 'foo.c', and will behave accordingly(1)(2). The +following Makefile does not explicitly instruct 'make' how to build +'foo.c' from 'foo.l'. Instead, it relies on the implicit rules of the +'make' program to build the intermediate file, 'scan.c': # Basic Makefile -- relies on implicit rules # Creates "myprogram" from "scan.l" and "myprogram.c" @@ -7150,8 +7098,9 @@ following Makefile does not explicitly instruct `make' how to build myprogram: scan.o myprogram.o scan.o: scan.l - For simple cases, the above may be sufficient. For other cases, you -may have to explicitly instruct `make' how to build your scanner. The + + For simple cases, the above may be sufficient. For other cases, you +may have to explicitly instruct 'make' how to build your scanner. The following is an example of a Makefile containing explicit rules: # Basic Makefile -- provides explicit rules @@ -7173,16 +7122,17 @@ following is an example of a Makefile containing explicit rules: clean: $(RM) *.o scan.c - Notice in the above example that `scan.c' is in the `clean' target. -This is because we consider the file `scan.c' to be an intermediate + + Notice in the above example that 'scan.c' is in the 'clean' target. +This is because we consider the file 'scan.c' to be an intermediate file. - Finally, we provide a realistic example of a `flex' scanner used -with a `bison' parser(3). There is a tricky problem we have to deal -with. Since a `flex' scanner will typically include a header file -(e.g., `y.tab.h') generated by the parser, we need to be sure that the -header file is generated BEFORE the scanner is compiled. We handle this -case in the following example: + Finally, we provide a realistic example of a 'flex' scanner used with +a 'bison' parser(3). There is a tricky problem we have to deal with. +Since a 'flex' scanner will typically include a header file (e.g., +'y.tab.h') generated by the parser, we need to be sure that the header +file is generated BEFORE the scanner is compiled. We handle this case +in the following example: # Makefile example -- scanner and parser. # Creates "myprogram" from "scan.l", "parse.y", and "myprogram.c" @@ -7197,25 +7147,26 @@ case in the following example: parse.o: parse.y myprogram.o: myprogram.c + In the above example, notice the line, scan.o: scan.l parse.c - , which lists the file `parse.c' (the generated parser) as a -dependency of `scan.o'. We want to ensure that the parser is created + , which lists the file 'parse.c' (the generated parser) as a +dependency of 'scan.o'. We want to ensure that the parser is created before the scanner is compiled, and the above line seems to do the -trick. Feel free to experiment with your specific implementation of -`make'. +trick. Feel free to experiment with your specific implementation of +'make'. - For more details on writing Makefiles, see *note Top: (make)Top. + For more details on writing Makefiles, see *note (make)Top::. ---------- Footnotes ---------- - (1) GNU `make' and GNU `automake' are two such programs that provide + (1) GNU 'make' and GNU 'automake' are two such programs that provide implicit rules for flex-generated scanners. - (2) GNU `automake' may generate code to execute flex in -lex-compatible mode, or to stdout. If this is not what you want, then + (2) GNU 'automake' may generate code to execute flex in +lex-compatible mode, or to stdout. If this is not what you want, then you should provide an explicit rule in your Makefile.am (3) This example also applies to yacc parsers. @@ -7226,34 +7177,33 @@ File: flex.info, Node: Bison Bridge, Next: M4 Dependency, Prev: Makefiles and A.2 C Scanners with Bison Parsers ================================= -This section describes the `flex' features useful when integrating -`flex' with `GNU bison'(1). Skip this section if you are not using -`bison' with your scanner. Here we discuss only the `flex' half of the -`flex' and `bison' pair. We do not discuss `bison' in any detail. For -more information about generating `bison' parsers, see *note Top: -(bison)Top. - - A compatible `bison' scanner is generated by declaring `%option -bison-bridge' or by supplying `--bison-bridge' when invoking `flex' -from the command line. This instructs `flex' that the macro `yylval' -may be used. The data type for `yylval', `YYSTYPE', is typically -defined in a header file, included in section 1 of the `flex' input -file. For a list of functions and macros available, *Note -bison-functions::. +This section describes the 'flex' features useful when integrating +'flex' with 'GNU bison'(1). Skip this section if you are not using +'bison' with your scanner. Here we discuss only the 'flex' half of the +'flex' and 'bison' pair. We do not discuss 'bison' in any detail. For +more information about generating 'bison' parsers, see *note +(bison)Top::. + + A compatible 'bison' scanner is generated by declaring '%option +bison-bridge' or by supplying '--bison-bridge' when invoking 'flex' from +the command line. This instructs 'flex' that the macro 'yylval' may be +used. The data type for 'yylval', 'YYSTYPE', is typically defined in a +header file, included in section 1 of the 'flex' input file. For a list +of functions and macros available, *Note bison-functions::. The declaration of yylex becomes, int yylex ( YYSTYPE * lvalp, yyscan_t scanner ); - If `%option bison-locations' is specified, then the declaration + If '%option bison-locations' is specified, then the declaration becomes, int yylex ( YYSTYPE * lvalp, YYLTYPE * llocp, yyscan_t scanner ); - Note that the macros `yylval' and `yylloc' evaluate to pointers. -Support for `yylloc' is optional in `bison', so it is optional in -`flex' as well. The following is an example of a `flex' scanner that is -compatible with `bison'. + Note that the macros 'yylval' and 'yylloc' evaluate to pointers. +Support for 'yylloc' is optional in 'bison', so it is optional in 'flex' +as well. The following is an example of a 'flex' scanner that is +compatible with 'bison'. /* Scanner for "C" assignment statements... sort of. */ %{ @@ -7269,10 +7219,10 @@ compatible with `bison'. . {} % - As you can see, there really is no magic here. We just use `yylval' -as we would any other variable. The data type of `yylval' is generated -by `bison', and included in the file `y.tab.h'. Here is the -corresponding `bison' parser: + As you can see, there really is no magic here. We just use 'yylval' +as we would any other variable. The data type of 'yylval' is generated +by 'bison', and included in the file 'y.tab.h'. Here is the +corresponding 'bison' parser: /* Parser to convert "C" assignments to lisp. */ %{ @@ -7307,34 +7257,33 @@ File: flex.info, Node: M4 Dependency, Next: Common Patterns, Prev: Bison Brid A.3 M4 Dependency ================= -The macro processor `m4'(1) must be installed wherever flex is -installed. `flex' invokes `m4', found by searching the directories in -the `PATH' environment variable. Any code you place in section 1 or in -the actions will be sent through m4. Please follow these rules to -protect your code from unwanted `m4' processing. +The macro processor 'm4'(1) must be installed wherever flex is +installed. 'flex' invokes 'm4', found by searching the directories in +the 'PATH' environment variable. Any code you place in section 1 or in +the actions will be sent through m4. Please follow these rules to +protect your code from unwanted 'm4' processing. - * Do not use symbols that begin with, `m4_', such as, `m4_define', - or `m4_include', since those are reserved for `m4' macro names. If + * Do not use symbols that begin with, 'm4_', such as, 'm4_define', or + 'm4_include', since those are reserved for 'm4' macro names. If for some reason you need m4_ as a prefix, use a preprocessor #define to get your symbol past m4 unmangled. - * Do not use the strings `[[' or `]]' anywhere in your code. The + * Do not use the strings '[[' or ']]' anywhere in your code. The former is not valid in C, except within comments and strings, but - the latter is valid in code such as `x[y[z]]'. The solution is - simple. To get the literal string `"]]"', use `"]""]"'. To get the - array notation `x[y[z]]', use `x[y[z] ]'. Flex will attempt to - detect these sequences in user code, and escape them. However, - it's best to avoid this complexity where possible, by removing - such sequences from your code. - + the latter is valid in code such as 'x[y[z]]'. The solution is + simple. To get the literal string '"]]"', use '"]""]"'. To get + the array notation 'x[y[z]]', use 'x[y[z] ]'. Flex will attempt to + detect these sequences in user code, and escape them. However, + it's best to avoid this complexity where possible, by removing such + sequences from your code. - `m4' is only required at the time you run `flex'. The generated -scanner is ordinary C or C++, and does _not_ require `m4'. + 'm4' is only required at the time you run 'flex'. The generated +scanner is ordinary C or C++, and does _not_ require 'm4'. ---------- Footnotes ---------- (1) The use of m4 is subject to change in future revisions of flex. -It is not part of the public API of flex. Do not depend on it. +It is not part of the public API of flex. Do not depend on it. File: flex.info, Node: Common Patterns, Prev: M4 Dependency, Up: Appendices @@ -7347,10 +7296,10 @@ use in your scanner. * Menu: -* Numbers:: -* Identifiers:: -* Quoted Constructs:: -* Addresses:: +* Numbers:: +* Identifiers:: +* Quoted Constructs:: +* Addresses:: File: flex.info, Node: Numbers, Next: Identifiers, Up: Common Patterns @@ -7359,13 +7308,13 @@ A.4.1 Numbers ------------- C99 decimal constant - `([[:digit:]]{-}[0])[[:digit:]]*' + '([[:digit:]]{-}[0])[[:digit:]]*' C99 hexadecimal constant - `0[xX][[:xdigit:]]+' + '0[xX][[:xdigit:]]+' C99 octal constant - `0[01234567]*' + '0[01234567]*' C99 floating point constant {dseq} ([[:digit:]]+) @@ -7387,7 +7336,6 @@ C99 floating point constant See C99 section 6.4.4.2 for the gory details. - File: flex.info, Node: Identifiers, Next: Quoted Constructs, Prev: Numbers, Up: Common Patterns @@ -7401,13 +7349,12 @@ C99 Identifier Technically, the above pattern does not encompass all possible C99 identifiers, since C99 allows for "implementation-defined" - characters. In practice, C compilers follow the above pattern, - with the addition of the `$' character. + characters. In practice, C compilers follow the above pattern, + with the addition of the '$' character. UTF-8 Encoded Unicode Code Point [\x09\x0A\x0D\x20-\x7E]|[\xC2-\xDF][\x80-\xBF]|\xE0[\xA0-\xBF][\x80-\xBF]|[\xE1-\xEC\xEE\xEF]([\x80-\xBF]{2})|\xED[\x80-\x9F][\x80-\xBF]|\xF0[\x90-\xBF]([\x80-\xBF]{2})|[\xF1-\xF3]([\x80-\xBF]{3})|\xF4[\x80-\x8F]([\x80-\xBF]{2}) - File: flex.info, Node: Quoted Constructs, Next: Addresses, Prev: Identifiers, Up: Common Patterns @@ -7415,20 +7362,20 @@ A.4.3 Quoted Constructs ----------------------- C99 String Literal - `L?\"([^\"\\\n]|(\\['\"?\\abfnrtv])|(\\([0123456]{1,3}))|(\\x[[:xdigit:]]+)|(\\u([[:xdigit:]]{4}))|(\\U([[:xdigit:]]{8})))*\"' + 'L?\"([^\"\\\n]|(\\['\"?\\abfnrtv])|(\\([0123456]{1,3}))|(\\x[[:xdigit:]]+)|(\\u([[:xdigit:]]{4}))|(\\U([[:xdigit:]]{8})))*\"' C99 Comment - `("/*"([^*]|"*"[^/])*"*/")|("/"(\\\n)*"/"[^\n]*)' + '("/*"([^*]|"*"[^/])*"*/")|("/"(\\\n)*"/"[^\n]*)' - Note that in C99, a `//'-style comment may be split across lines, - and, contrary to popular belief, does not include the trailing - `\n' character. + Note that in C99, a '//'-style comment may be split across lines, + and, contrary to popular belief, does not include the trailing '\n' + character. - A better way to scan `/* */' comments is by line, rather than - matching possibly huge comments all at once. This will allow you - to scan comments of unlimited length, as long as line breaks - appear at sane intervals. This is also more efficient when used - with automatic line number processing. *Note option-yylineno::. + A better way to scan '/* */' comments is by line, rather than + matching possibly huge comments all at once. This will allow you + to scan comments of unlimited length, as long as line breaks appear + at sane intervals. This is also more efficient when used with + automatic line number processing. *Note option-yylineno::. <INITIAL>{ "/*" BEGIN(COMMENT); @@ -7440,7 +7387,6 @@ C99 Comment \n ; } - File: flex.info, Node: Addresses, Prev: Quoted Constructs, Up: Common Patterns @@ -7465,17 +7411,16 @@ IPv6 Address (({h16}:){0,6}{h16})?:: See RFC 2373 (http://www.ietf.org/rfc/rfc2373.txt) for details. - Note that you have to fold the definition of `IPv6address' into one + Note that you have to fold the definition of 'IPv6address' into one line and that it also matches the "unspecified address" "::". URI - `(([^:/?#]+):)?("//"([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?' + '(([^:/?#]+):)?("//"([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?' This pattern is nearly useless, since it allows just about any character to appear in a URI, including spaces and control - characters. See RFC 2396 (http://www.ietf.org/rfc/rfc2396.txt) - for details. - + characters. See RFC 2396 (http://www.ietf.org/rfc/rfc2396.txt) for + details. File: flex.info, Node: Indices, Prev: Appendices, Up: Top @@ -7485,10 +7430,367 @@ Indices * Menu: -* Concept Index:: -* Index of Functions and Macros:: -* Index of Variables:: -* Index of Data Types:: -* Index of Hooks:: -* Index of Scanner Options:: +* Concept Index:: +* Index of Functions and Macros:: +* Index of Variables:: +* Index of Data Types:: +* Index of Hooks:: +* Index of Scanner Options:: + + +File: flex.info, Node: Concept Index, Next: Index of Functions and Macros, Prev: Indices, Up: Indices + +Concept Index +============= + + +* Menu: + +* $ as normal character in patterns: Patterns. (line 275) +* %array, advantages of: Matching. (line 43) +* %array, use of: Matching. (line 29) +* %array, with C++: Matching. (line 65) +* %option noyywrapp: Generated Scanner. (line 93) +* %pointer, and unput(): Actions. (line 162) +* %pointer, use of: Matching. (line 29) +* %top: Definitions Section. (line 44) +* %{ and %}, in Definitions Section: Definitions Section. (line 40) +* %{ and %}, in Rules Section: Actions. (line 26) +* <<EOF>>, use of: EOF. (line 33) +* [] in patterns: Patterns. (line 15) +* ^ as non-special character in patterns: Patterns. (line 275) +* |, in actions: Actions. (line 33) +* |, use of: Actions. (line 83) +* accessor functions, use of: Accessor Methods. (line 18) +* actions: Actions. (line 6) +* actions, embedded C strings: Actions. (line 26) +* actions, redefining YY_BREAK: Misc Macros. (line 49) +* actions, use of { and }: Actions. (line 26) +* aliases, how to define: Definitions Section. (line 10) +* arguments, command-line: Scanner Options. (line 6) +* array, default size for yytext: User Values. (line 13) +* backing up, eliminating: Performance. (line 54) +* backing up, eliminating by adding error rules: Performance. (line 104) +* backing up, eliminating with catch-all rule: Performance. (line 118) +* backing up, example of eliminating: Performance. (line 49) +* BEGIN: Actions. (line 57) +* BEGIN, explanation: Start Conditions. (line 84) +* beginning of line, in patterns: Patterns. (line 127) +* bison, bridging with flex: Bison Bridge. (line 6) +* bison, parser: Bison Bridge. (line 53) +* bison, scanner to be called from bison: Bison Bridge. (line 34) +* BOL, checking the BOL flag: Misc Macros. (line 46) +* BOL, in patterns: Patterns. (line 127) +* BOL, setting it: Misc Macros. (line 40) +* braces in patterns: Patterns. (line 42) +* bugs, reporting: Reporting Bugs. (line 6) +* C code in flex input: Definitions Section. (line 40) +* C++: Cxx. (line 9) +* C++ and %array: User Values. (line 23) +* C++ I/O, customizing: How do I use my own I/O classes in a C++ scanner?. + (line 9) +* C++ scanners, including multiple scanners: Cxx. (line 197) +* C++ scanners, use of: Cxx. (line 128) +* c++, experimental form of scanner class: Cxx. (line 6) +* C++, multiple different scanners: Cxx. (line 192) +* C-strings, in actions: Actions. (line 26) +* case-insensitive, effect on character classes: Patterns. (line 216) +* character classes in patterns: Patterns. (line 186) +* character classes in patterns, syntax of: Patterns. (line 15) +* character classes, equivalence of: Patterns. (line 205) +* clearing an input buffer: Multiple Input Buffers. + (line 66) +* command-line options: Scanner Options. (line 6) +* comments in flex input: Definitions Section. (line 37) +* comments in the input: Comments in the Input. + (line 24) +* comments, discarding: Actions. (line 176) +* comments, example of scanning C comments: Start Conditions. (line 140) +* comments, in actions: Actions. (line 26) +* comments, in rules section: Comments in the Input. + (line 11) +* comments, syntax of: Comments in the Input. + (line 6) +* comments, valid uses of: Comments in the Input. + (line 24) +* compressing whitespace: Actions. (line 22) +* concatenation, in patterns: Patterns. (line 111) +* copyright of flex: Copyright. (line 6) +* counting characters and lines: Simple Examples. (line 23) +* customizing I/O in C++ scanners: How do I use my own I/O classes in a C++ scanner?. + (line 9) +* default rule: Simple Examples. (line 15) +* default rule <1>: Matching. (line 20) +* defining pattern aliases: Definitions Section. (line 21) +* Definitions, in flex input: Definitions Section. (line 6) +* deleting lines from input: Actions. (line 13) +* discarding C comments: Actions. (line 176) +* distributing flex: Copyright. (line 6) +* ECHO: Actions. (line 54) +* ECHO, and yyout: Generated Scanner. (line 101) +* embedding C code in flex input: Definitions Section. (line 40) +* end of file, in patterns: Patterns. (line 150) +* end of line, in negated character classes: Patterns. (line 237) +* end of line, in patterns: Patterns. (line 131) +* end-of-file, and yyrestart(): Generated Scanner. (line 42) +* EOF and yyrestart(): Generated Scanner. (line 42) +* EOF in patterns, syntax of: Patterns. (line 150) +* EOF, example using multiple input buffers: Multiple Input Buffers. + (line 81) +* EOF, explanation: EOF. (line 6) +* EOF, pushing back: Actions. (line 170) +* EOL, in negated character classes: Patterns. (line 237) +* EOL, in patterns: Patterns. (line 131) +* error messages, end of buffer missed: Lex and Posix. (line 50) +* error reporting, diagnostic messages: Diagnostics. (line 6) +* error reporting, in C++: Cxx. (line 112) +* error rules, to eliminate backing up: Performance. (line 102) +* escape sequences in patterns, syntax of: Patterns. (line 57) +* exiting with yyterminate(): Actions. (line 212) +* experimental form of c++ scanner class: Cxx. (line 6) +* extended scope of start conditions: Start Conditions. (line 270) +* file format: Format. (line 6) +* file format, serialized tables: Tables File Format. (line 6) +* flushing an input buffer: Multiple Input Buffers. + (line 66) +* flushing the internal buffer: Actions. (line 206) +* format of flex input: Format. (line 6) +* format of input file: Format. (line 9) +* freeing tables: Loading and Unloading Serialized Tables. + (line 6) +* getting current start state with YY_START: Start Conditions. + (line 189) +* halting with yyterminate(): Actions. (line 212) +* handling include files with multiple input buffers: Multiple Input Buffers. + (line 87) +* handling include files with multiple input buffers <1>: Multiple Input Buffers. + (line 122) +* header files, with C++: Cxx. (line 197) +* include files, with C++: Cxx. (line 197) +* input file, Definitions section: Definitions Section. (line 6) +* input file, Rules Section: Rules Section. (line 6) +* input file, user code Section: User Code Section. (line 6) +* input(): Actions. (line 173) +* input(), and C++: Actions. (line 202) +* input, format of: Format. (line 6) +* input, matching: Matching. (line 6) +* keywords, for performance: Performance. (line 200) +* lex (traditional) and POSIX: Lex and Posix. (line 6) +* LexerInput, overriding: How do I use my own I/O classes in a C++ scanner?. + (line 9) +* LexerOutput, overriding: How do I use my own I/O classes in a C++ scanner?. + (line 9) +* limitations of flex: Limitations. (line 6) +* literal text in patterns, syntax of: Patterns. (line 54) +* loading tables at runtime: Loading and Unloading Serialized Tables. + (line 6) +* m4: M4 Dependency. (line 6) +* Makefile, example of implicit rules: Makefiles and Flex. (line 21) +* Makefile, explicit example: Makefiles and Flex. (line 33) +* Makefile, syntax: Makefiles and Flex. (line 6) +* matching C-style double-quoted strings: Start Conditions. (line 203) +* matching, and trailing context: Matching. (line 6) +* matching, length of: Matching. (line 6) +* matching, multiple matches: Matching. (line 6) +* member functions, C++: Cxx. (line 9) +* memory management: Memory Management. (line 6) +* memory, allocating input buffers: Multiple Input Buffers. + (line 19) +* memory, considerations for reentrant scanners: Init and Destroy Functions. + (line 6) +* memory, deleting input buffers: Multiple Input Buffers. + (line 46) +* memory, for start condition stacks: Start Conditions. (line 301) +* memory, serialized tables: Serialized Tables. (line 6) +* memory, serialized tables <1>: Loading and Unloading Serialized Tables. + (line 6) +* methods, c++: Cxx. (line 9) +* minimal scanner: Matching. (line 24) +* multiple input streams: Multiple Input Buffers. + (line 6) +* name definitions, not POSIX: Lex and Posix. (line 75) +* negating ranges in patterns: Patterns. (line 23) +* newline, matching in patterns: Patterns. (line 135) +* non-POSIX features of flex: Lex and Posix. (line 142) +* noyywrap, %option: Generated Scanner. (line 93) +* NULL character in patterns, syntax of: Patterns. (line 62) +* octal characters in patterns: Patterns. (line 65) +* options, command-line: Scanner Options. (line 6) +* overriding LexerInput: How do I use my own I/O classes in a C++ scanner?. + (line 9) +* overriding LexerOutput: How do I use my own I/O classes in a C++ scanner?. + (line 9) +* overriding the memory routines: Overriding The Default Memory Management. + (line 38) +* Pascal-like language: Simple Examples. (line 49) +* pattern aliases, defining: Definitions Section. (line 21) +* pattern aliases, expansion of: Patterns. (line 51) +* pattern aliases, how to define: Definitions Section. (line 10) +* pattern aliases, use of: Definitions Section. (line 28) +* patterns and actions on different lines: Lex and Posix. (line 101) +* patterns, character class equivalence: Patterns. (line 205) +* patterns, common: Common Patterns. (line 6) +* patterns, end of line: Patterns. (line 300) +* patterns, grouping and precedence: Patterns. (line 167) +* patterns, in rules section: Patterns. (line 6) +* patterns, invalid trailing context: Patterns. (line 285) +* patterns, matching: Matching. (line 6) +* patterns, precedence of operators: Patterns. (line 161) +* patterns, repetitions with grouping: Patterns. (line 184) +* patterns, special characters treated as non-special: Patterns. + (line 293) +* patterns, syntax: Patterns. (line 9) +* patterns, syntax <1>: Patterns. (line 9) +* patterns, tuning for performance: Performance. (line 49) +* patterns, valid character classes: Patterns. (line 192) +* performance optimization, matching longer tokens: Performance. + (line 167) +* performance optimization, recognizing keywords: Performance. + (line 205) +* performance, backing up: Performance. (line 49) +* performance, considerations: Performance. (line 6) +* performance, using keywords: Performance. (line 200) +* popping an input buffer: Multiple Input Buffers. + (line 60) +* POSIX and lex: Lex and Posix. (line 6) +* POSIX comp;compliance: Lex and Posix. (line 142) +* POSIX, character classes in patterns, syntax of: Patterns. (line 15) +* preprocessor macros, for use in actions: Actions. (line 50) +* pushing an input buffer: Multiple Input Buffers. + (line 52) +* pushing back characters with unput: Actions. (line 143) +* pushing back characters with unput(): Actions. (line 147) +* pushing back characters with yyless: Actions. (line 131) +* pushing back EOF: Actions. (line 170) +* ranges in patterns: Patterns. (line 19) +* ranges in patterns, negating: Patterns. (line 23) +* recognizing C comments: Start Conditions. (line 143) +* reentrant scanners, multiple interleaved scanners: Reentrant Uses. + (line 10) +* reentrant scanners, recursive invocation: Reentrant Uses. (line 30) +* reentrant, accessing flex variables: Global Replacement. (line 6) +* reentrant, accessor functions: Accessor Methods. (line 6) +* reentrant, API explanation: Reentrant Overview. (line 6) +* reentrant, calling functions: Extra Reentrant Argument. + (line 6) +* reentrant, example of: Reentrant Example. (line 6) +* reentrant, explanation: Reentrant. (line 6) +* reentrant, extra data: Extra Data. (line 6) +* reentrant, initialization: Init and Destroy Functions. + (line 6) +* regular expressions, in patterns: Patterns. (line 6) +* REJECT: Actions. (line 61) +* REJECT, calling multiple times: Actions. (line 83) +* REJECT, performance costs: Performance. (line 12) +* reporting bugs: Reporting Bugs. (line 6) +* restarting the scanner: Lex and Posix. (line 54) +* RETURN, within actions: Generated Scanner. (line 57) +* rules, default: Simple Examples. (line 15) +* rules, in flex input: Rules Section. (line 6) +* scanner, definition of: Introduction. (line 6) +* sections of flex input: Format. (line 6) +* serialization: Serialized Tables. (line 6) +* serialization of tables: Creating Serialized Tables. + (line 6) +* serialized tables, multiple scanners: Creating Serialized Tables. + (line 26) +* stack, input buffer pop: Multiple Input Buffers. + (line 60) +* stack, input buffer push: Multiple Input Buffers. + (line 52) +* stacks, routines for manipulating: Start Conditions. (line 286) +* start condition, applying to multiple patterns: Start Conditions. + (line 258) +* start conditions: Start Conditions. (line 6) +* start conditions, behavior of default rule: Start Conditions. + (line 82) +* start conditions, exclusive: Start Conditions. (line 53) +* start conditions, for different interpretations of same input: Start Conditions. + (line 112) +* start conditions, in patterns: Patterns. (line 140) +* start conditions, inclusive: Start Conditions. (line 44) +* start conditions, inclusive v.s. exclusive: Start Conditions. + (line 24) +* start conditions, integer values: Start Conditions. (line 163) +* start conditions, multiple: Start Conditions. (line 17) +* start conditions, special wildcard condition: Start Conditions. + (line 68) +* start conditions, use of a stack: Start Conditions. (line 286) +* start conditions, use of wildcard condition (<*>): Start Conditions. + (line 72) +* start conditions, using BEGIN: Start Conditions. (line 95) +* stdin, default for yyin: Generated Scanner. (line 37) +* stdout, as default for yyout: Generated Scanner. (line 101) +* strings, scanning strings instead of files: Multiple Input Buffers. + (line 175) +* tables, creating serialized: Creating Serialized Tables. + (line 6) +* tables, file format: Tables File Format. (line 6) +* tables, freeing: Loading and Unloading Serialized Tables. + (line 6) +* tables, loading and unloading: Loading and Unloading Serialized Tables. + (line 6) +* terminating with yyterminate(): Actions. (line 212) +* token: Matching. (line 14) +* trailing context, in patterns: Patterns. (line 118) +* trailing context, limits of: Patterns. (line 275) +* trailing context, matching: Matching. (line 6) +* trailing context, performance costs: Performance. (line 12) +* trailing context, variable length: Performance. (line 141) +* unput(): Actions. (line 143) +* unput(), and %pointer: Actions. (line 162) +* unput(), pushing back characters: Actions. (line 147) +* user code, in flex input: User Code Section. (line 6) +* username expansion: Simple Examples. (line 8) +* using integer values of start condition names: Start Conditions. + (line 163) +* verbatim text in patterns, syntax of: Patterns. (line 54) +* warning, dangerous trailing context: Limitations. (line 20) +* warning, rule cannot be matched: Diagnostics. (line 14) +* warnings, diagnostic messages: Diagnostics. (line 6) +* whitespace, compressing: Actions. (line 22) +* yacc interface: Yacc. (line 17) +* yacc, interface: Yacc. (line 6) +* yyalloc, overriding: Overriding The Default Memory Management. + (line 6) +* yyfree, overriding: Overriding The Default Memory Management. + (line 6) +* yyin: Generated Scanner. (line 37) +* yyinput(): Actions. (line 202) +* yyleng: Matching. (line 14) +* yyleng, modification of: Actions. (line 47) +* yyless(): Actions. (line 125) +* yyless(), pushing back characters: Actions. (line 131) +* yylex(), in generated scanner: Generated Scanner. (line 6) +* yylex(), overriding: Generated Scanner. (line 16) +* yylex, overriding the prototype of: Generated Scanner. (line 20) +* yylineno, in a reentrant scanner: Reentrant Functions. (line 36) +* yylineno, performance costs: Performance. (line 12) +* yymore(): Actions. (line 104) +* yymore() to append token to previous token: Actions. (line 110) +* yymore(), mega-kludge: Actions. (line 110) +* yymore, and yyleng: Actions. (line 47) +* yymore, performance penalty of: Actions. (line 119) +* yyout: Generated Scanner. (line 101) +* yyrealloc, overriding: Overriding The Default Memory Management. + (line 6) +* yyrestart(): Generated Scanner. (line 42) +* yyterminate(): Actions. (line 212) +* yytext: Matching. (line 14) +* yytext, default array size: User Values. (line 13) +* yytext, memory considerations: A Note About yytext And Memory. + (line 6) +* yytext, modification of: Actions. (line 42) +* yytext, two types of: Matching. (line 29) +* yywrap(): Generated Scanner. (line 85) +* yywrap, default for: Generated Scanner. (line 93) +* YY_CURRENT_BUFFER, and multiple buffers Finally, the macro: Multiple Input Buffers. + (line 78) +* YY_EXTRA_TYPE, defining your own type: Extra Data. (line 33) +* YY_FLUSH_BUFFER: Actions. (line 206) +* YY_INPUT: Generated Scanner. (line 61) +* YY_INPUT, overriding: Generated Scanner. (line 71) +* YY_START, example: Start Conditions. (line 185) +* YY_USER_ACTION to track each time a rule is matched: Misc Macros. + (line 14) |