OSSP: CVS Repository: Difference in ossp-adm/autotools/flex.html versions 1.1 and 1.2

ossp-adm/autotools/flex.html 1.1 -> 1.2

--- flex.html 2002/07/10 08:46:25 1.1 +++ flex.html 2002/11/09 14:28:38 1.2 @@ -1,76 +1,147 @@ <HTML> <HEAD> - + -<TITLE>The Flex Manual</TITLE> +<TITLE>flex: a fast lexical analyzer generator</TITLE> </HEAD> <BODY> -<H1>The Flex Manual</H1> +<H1>Flex, version 2.5.23</H1> +<H2>A fast scanner generator</H2> +<H2>Edition 2.5.23, 21 October 2002</H2> +<ADDRESS>Vern Paxson</ADDRESS> +<ADDRESS>W. L. Estes</ADDRESS> +<ADDRESS>John Millaway</ADDRESS> <P> <P><HR><P> -<H1><A NAME="SEC1" HREF="flex_toc.html#TOC1">Introduction</A></H1> +<H1><A NAME="SEC1" HREF="flex_toc.html#TOC1">Copyright</A></H1> <P> <A NAME="IDX1"></A> -<CODE>flex</CODE> -is a tool for generating -<EM>scanners</EM>. -A scanner is a program which recognizes lexical patterns in text. -The -<CODE>flex</CODE> -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 -<EM>rules</EM>. <CODE>flex</CODE> -generates as output a C source file, -<TT>`lex.yy.c'</TT> by default, -which defines a routine -<B>yylex()</B>. -This file is compiled and linked with the -flex runtime library -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. +<A NAME="IDX2"></A> + + +<P> +The flex manual is placed under the same licensing conditions as the +rest of flex: + + +<P> +Copyright (C) 1990, 1997 The Regents of the University of California. +All rights reserved. + + +<P> +This code is derived from software contributed to Berkeley by +Vern Paxson. + + +<P> +The United States Government has rights in this work pursuant +to contract no. DE-AC03-76SF00098 between the United States +Department of Energy and the University of California. + + +<P> +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions +are met: + + + +<OL> +<LI> + + Redistributions of source code must retain the above copyright +notice, this list of conditions and the following disclaimer. + +<LI> + +Redistributions in binary form must reproduce the above copyright +notice, this list of conditions and the following disclaimer in the +documentation and/or other materials provided with the distribution. +</OL> + +<P> +Neither the name of the University nor the names of its contributors +may be used to endorse or promote products derived from this software +without specific prior written permission. + + +<P> +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. + + + +<H1><A NAME="SEC2" HREF="flex_toc.html#TOC2">Reporting Bugs</A></H1> +<P> +<A NAME="IDX3"></A> +<A NAME="IDX4"></A> + + +<P> +If you have problems with <CODE>flex</CODE> or think you have found a bug, +please send mail detailing your problem to +<A HREF="mailto:help-flex@gnu.org">help-flex@gnu.org</A>. Patches are always welcome. -<H1><A NAME="SEC2" HREF="flex_toc.html#TOC2">Some Simple Examples</A></H1> + + +<H1><A NAME="SEC3" HREF="flex_toc.html#TOC3">Introduction</A></H1> + +<P> +<A NAME="IDX5"></A> +<CODE>flex</CODE> is a tool for generating <EM>scanners</EM>. A scanner is a +program which recognizes lexical patterns in text. The <CODE>flex</CODE> +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 <EM>rules</EM>. <CODE>flex</CODE> generates as output a C source file, +<TT>`lex.yy.c'</TT> by default, which defines a routine <CODE>yylex()</CODE>. +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. + + + + +<H1><A NAME="SEC4" HREF="flex_toc.html#TOC4">Some Simple Examples</A></H1> <P> First some simple examples to get the flavor of how one uses <CODE>flex</CODE>. -The following -<CODE>flex</CODE> -input specifies a scanner which whenever it encounters the string -<SAMP>`username'</SAMP> will replace it with the user's login name: <P> +<A NAME="IDX6"></A> +The following <CODE>flex</CODE> input specifies a scanner which, when it +encounters the string <SAMP>`username'</SAMP> will replace it with the user's +login name: + + + +<PRE> @verbatim %% username printf( "%s", getlogin() ); - +</PRE> <P> -<A NAME="IDX2"></A> -By default, any text not matched by a -<CODE>flex</CODE> -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 <SAMP>`username'</SAMP> expanded. -In this input, there is just one rule. <SAMP>`username'</SAMP> is the -<EM>pattern</EM> -and the <SAMP>`printf'</SAMP> is the -<EM>action</EM>. -The <SAMP>`%%'</SAMP> symbol marks the beginning of the rules. +<A NAME="IDX7"></A> +<A NAME="IDX8"></A> +By default, any text not matched by a <CODE>flex</CODE> 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 <SAMP>`username'</SAMP> expanded. In this +input, there is just one rule. <SAMP>`username'</SAMP> is the <EM>pattern</EM> and +the <SAMP>`printf'</SAMP> is the <EM>action</EM>. The <SAMP>`%%'</SAMP> symbol marks the +beginning of the rules. <P> @@ -78,7 +149,7 @@ <P> -<A NAME="IDX3"></A> +<A NAME="IDX9"></A> <PRE> @verbatim @@ -98,18 +169,15 @@ </PRE> <P> -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 counts). The first line -declares two globals, <CODE>num_lines</CODE> and <CODE>num_chars</CODE>, which are accessible -both inside -<CODE>yylex()</CODE> -and in the -<CODE>main()</CODE> -routine declared after the second <SAMP>`%%'</SAMP>. There are two rules, one -which matches a newline (<SAMP>`\n'</SAMP>) and increments both the line count and -the character count, and one which matches any character other than -a newline (indicated by the <SAMP>`.'</SAMP> regular expression). +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 +character and line counts. The first line declares two globals, +<CODE>num_lines</CODE> and <CODE>num_chars</CODE>, which are accessible both inside +<CODE>yylex()</CODE> and in the <CODE>main()</CODE> routine declared after the +second <SAMP>`%%'</SAMP>. There are two rules, one which matches a newline +(<SAMP>`\n'</SAMP>) and increments both the line count and the character count, +and one which matches any character other than a newline (indicated by +the <SAMP>`.'</SAMP> regular expression). <P> @@ -117,7 +185,7 @@ <P> -<A NAME="IDX4"></A> +<A NAME="IDX10"></A> <PRE> @verbatim @@ -168,16 +236,15 @@ yyin = fopen( argv[0], "r" ); else yyin = stdin; - + yylex(); } </PRE> <P> -This is the beginnings of a simple scanner for a language like -Pascal. It identifies different types of -<EM>tokens</EM> -and reports on what it has seen. +This is the beginnings of a simple scanner for a language like Pascal. +It identifies different types of <EM>tokens</EM> and reports on what it has +seen. <P> @@ -187,24 +254,22 @@ -<H1><A NAME="SEC3" HREF="flex_toc.html#TOC3">Format of the Input File</A></H1> +<H1><A NAME="SEC5" HREF="flex_toc.html#TOC5">Format of the Input File</A></H1> <P> -<A NAME="IDX5"></A> -<A NAME="IDX6"></A> -<A NAME="IDX7"></A> +<A NAME="IDX11"></A> +<A NAME="IDX12"></A> +<A NAME="IDX13"></A> +<A NAME="IDX14"></A> <P> -The -<CODE>flex</CODE> -input file consists of three sections, separated by a line with just -<SAMP>`%%'</SAMP> -in it: +The <CODE>flex</CODE> input file consists of three sections, separated by a +line containing only <SAMP>`%%'</SAMP>. <P> -<A NAME="IDX8"></A> +<A NAME="IDX15"></A> <PRE> @verbatim @@ -217,25 +282,19 @@ -<H2><A NAME="SEC4" HREF="flex_toc.html#TOC4">Format of the Definitions Section</A></H2> -<P> -<A NAME="IDX9"></A> -<A NAME="IDX10"></A> -<A NAME="IDX11"></A> - +<H2><A NAME="SEC6" HREF="flex_toc.html#TOC6">Format of the Definitions Section</A></H2> <P> -The -<I>definitions</I> -section contains declarations of simple -<I>name</I> +<A NAME="IDX16"></A> +<A NAME="IDX17"></A> +The <EM>definitions section</EM> contains declarations of simple <EM>name</EM> definitions to simplify the scanner specification, and declarations of -<I>start conditions</I>, -which are explained in a later section. +<EM>start conditions</EM>, which are explained in a later section. <P> -<A NAME="IDX12"></A> +<A NAME="IDX18"></A> +<A NAME="IDX19"></A> Name definitions have the form: @@ -246,16 +305,17 @@ </PRE> <P> -The <SAMP>`name'</SAMP> is a word beginning with a letter or an underscore (<SAMP>`_'</SAMP>) -followed by zero or more letters, digits, <SAMP>`_'</SAMP>, or <SAMP>`-'</SAMP> (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 <SAMP>`{name}'</SAMP>, which -will expand to <SAMP>`(definition)'</SAMP>. For example, +The <SAMP>`name'</SAMP> is a word beginning with a letter or an underscore +(<SAMP>`_'</SAMP>) followed by zero or more letters, digits, <SAMP>`_'</SAMP>, or +<SAMP>`-'</SAMP> (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 +<SAMP>`{name}'</SAMP>, which will expand to <SAMP>`(definition)'</SAMP>. For example, <P> -<A NAME="IDX13"></A> +<A NAME="IDX20"></A> +<A NAME="IDX21"></A> <PRE> @verbatim @@ -264,15 +324,13 @@ </PRE> <P> -Defines <SAMP>`DIGIT'</SAMP> to be a regular expression which matches a -single digit, and -<SAMP>`ID'</SAMP> to be a regular expression which matches a letter -followed by zero-or-more letters-or-digits. -A subsequent reference to +Defines <SAMP>`DIGIT'</SAMP> to be a regular expression which matches a single +digit, and <SAMP>`ID'</SAMP> to be a regular expression which matches a letter +followed by zero-or-more letters-or-digits. A subsequent reference to <P> -<A NAME="IDX14"></A> +<A NAME="IDX22"></A> <PRE> @verbatim @@ -290,46 +348,36 @@ </PRE> <P> -and matches one-or-more digits followed by a '.' followed -by zero-or-more digits. +and matches one-or-more digits followed by a <SAMP>`.'</SAMP> followed by +zero-or-more digits. <P> +<A NAME="IDX23"></A> An unindented comment (i.e., a line beginning with <SAMP>`/*'</SAMP>) is copied verbatim to the output up to the next <SAMP>`*/'</SAMP>. <P> -<A NAME="IDX15"></A> -<A NAME="IDX16"></A> -<A NAME="IDX17"></A> - -Any -<EM>indented</EM> -text or text enclosed in -<SAMP>`%{'</SAMP> -and -<SAMP>`%}'</SAMP> -is also copied verbatim to the output (with the %{ and %} symbols removed). -The %{ and %} symbols must appear unindented on lines by themselves. - +<A NAME="IDX24"></A> +<A NAME="IDX25"></A> +<A NAME="IDX26"></A> +Any <EM>indented</EM> text or text enclosed in <SAMP>`%{'</SAMP> and <SAMP>`%}'</SAMP> +is also copied verbatim to the output (with the %{ and %} symbols +removed). The %{ and %} symbols must appear unindented on lines by +themselves. -<H2><A NAME="SEC5" HREF="flex_toc.html#TOC5">Format of the Rules Section</A></H2> -<P> -<A NAME="IDX18"></A> -<A NAME="IDX19"></A> -<A NAME="IDX20"></A> +<H2><A NAME="SEC7" HREF="flex_toc.html#TOC7">Format of the Rules Section</A></H2> <P> -The -<I>rules</I> -section of the -<CODE>flex</CODE> -input contains a series of rules of the form: +<A NAME="IDX27"></A> +<A NAME="IDX28"></A> +The <EM>rules</EM> section of the <CODE>flex</CODE> input contains a series of +rules of the form: @@ -341,93 +389,78 @@ <P> where the pattern must be unindented and the action must begin on the same line. +See section <A HREF="flex.html#SEC10">Patterns</A>, for a further description of patterns and actions. <P> -See section <A HREF="flex.html#SEC8">Patterns</A>, 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 +meaning is not well-defined and it may well cause compile-time errors +(this feature is present for @acronym{POSIX} compliance. See section <A HREF="flex.html#SEC42">Incompatibilities with Lex and Posix</A>, for other such features). <P> -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 meaning is not well-defined and it may well cause compile-time -errors (this feature is present for -<I>POSIX</I> -compliance. See section <A HREF="flex.html#SEC36">Incompatibilities with Lex and Posix</A>, for other such features). - - -<P> -Any -<EM>indented</EM> -text or text enclosed in -<SAMP>`%{'</SAMP> -and -<SAMP>`%}'</SAMP> +Any <EM>indented</EM> text or text enclosed in <SAMP>`%{'</SAMP> and <SAMP>`%}'</SAMP> is copied verbatim to the output (with the %{ and %} symbols removed). The %{ and %} symbols must appear unindented on lines by themselves. -<H2><A NAME="SEC6" HREF="flex_toc.html#TOC6">Format of the User Code Section</A></H2> -<P> -<A NAME="IDX21"></A> -<A NAME="IDX22"></A> -<A NAME="IDX23"></A> - +<H2><A NAME="SEC8" HREF="flex_toc.html#TOC8">Format of the User Code Section</A></H2> <P> -The user code section is simply copied to -<TT>`lex.yy.c'</TT> -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 -<SAMP>`%%'</SAMP> -in the input file may be skipped, too. - +<A NAME="IDX29"></A> +<A NAME="IDX30"></A> +The user code section is simply copied to <TT>`lex.yy.c'</TT> 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 +<SAMP>`%%'</SAMP> in the input file may be skipped, too. -<H2><A NAME="SEC7" HREF="flex_toc.html#TOC7">Comments in the Input</A></H2> -<P> -<A NAME="IDX24"></A> +<H2><A NAME="SEC9" HREF="flex_toc.html#TOC9">Comments in the Input</A></H2> <P> +<A NAME="IDX31"></A> 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: +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: <UL> -<LI>Comments may not appear in the Rules Section wherever flex is expecting +<LI> -a regular expression. This means comments may not appear at the beginning of -a line, or immediately following a list of scanner states. -<LI>Comments may not appear on an <SAMP>`%option'</SAMP> line in the Definitions Section. +<A NAME="IDX32"></A> + +Comments may not appear in the Rules Section wherever flex is expecting +a regular expression. This means comments may not appear at the +beginning of a line, or immediately following a list of scanner states. +<LI> +Comments may not appear on an <SAMP>`%option'</SAMP> line in the Definitions +Section. </UL> <P> -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 <SAMP>`/*'</SAMP>). -This rule will work anywhere in the input file. +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 +<SAMP>`/*'</SAMP>). This rule will work anywhere in the input file. <P> -All the comments in the following example are OK: +All the comments in the following example are valid: <P> -<A NAME="IDX25"></A> -<A NAME="IDX26"></A> +<A NAME="IDX33"></A> +<A NAME="IDX34"></A> <PRE> @verbatim @@ -456,19 +489,18 @@ -<H1><A NAME="SEC8" HREF="flex_toc.html#TOC8">Patterns</A></H1> -<P> -<A NAME="IDX27"></A> - +<H1><A NAME="SEC10" HREF="flex_toc.html#TOC10">Patterns</A></H1> <P> -The patterns in the input are written using an extended set of regular -expressions. These are: +<A NAME="IDX35"></A> +<A NAME="IDX36"></A> +The patterns in the input (see section <A HREF="flex.html#SEC7">Format of the Rules Section</A>) are written using an +extended set of regular expressions. These are: <P> -<A NAME="IDX28"></A> -<A NAME="IDX29"></A> +<A NAME="IDX37"></A> +<A NAME="IDX38"></A> <DL COMPACT> <DT><SAMP>`x'</SAMP> @@ -479,23 +511,23 @@ <DD> any character (byte) except newline -<A NAME="IDX30"></A> -<A NAME="IDX31"></A> +<A NAME="IDX39"></A> +<A NAME="IDX40"></A> +<A NAME="IDX41"></A> <DT><SAMP>`[xyz]'</SAMP> <DD> a <EM>character class</EM>; in this case, the pattern matches either an 'x', a 'y', or a 'z' -<A NAME="IDX32"></A> -<A NAME="IDX33"></A> +<A NAME="IDX42"></A> <DT><SAMP>`[abj-oZ]'</SAMP> <DD> a "character class" with a range in it; matches an 'a', a 'b', any letter from 'j' through 'o', or a 'Z' -<A NAME="IDX34"></A> -<A NAME="IDX35"></A> +<A NAME="IDX43"></A> +<A NAME="IDX44"></A> <DT><SAMP>`[^A-Z]'</SAMP> <DD> a "negated character class", i.e., any character @@ -519,6 +551,7 @@ <DD> zero or one r's (that is, "an optional r") +<A NAME="IDX45"></A> <DT><SAMP>`r{2,5}'</SAMP> <DD> anywhere from two to five r's @@ -531,31 +564,31 @@ <DD> exactly 4 r's -<A NAME="IDX36"></A> +<A NAME="IDX46"></A> <DT><SAMP>`{name}'</SAMP> <DD> the expansion of the <SAMP>`name'</SAMP> definition -(see section <A HREF="flex.html#SEC3">Format of the Input File</A>). +(see section <A HREF="flex.html#SEC5">Format of the Input File</A>). -<A NAME="IDX37"></A> -<A NAME="IDX38"></A> +<A NAME="IDX47"></A> +<A NAME="IDX48"></A> <DT><SAMP>`"[xyz]\"foo"'</SAMP> <DD> the literal string: <SAMP>`[xyz]"foo'</SAMP> -<A NAME="IDX39"></A> +<A NAME="IDX49"></A> <DT><SAMP>`\X'</SAMP> <DD> -if X is <SAMP>`a'</SAMP>, <SAMP>`b'</SAMP>, <SAMP>`f'</SAMP>, <SAMP>`n'</SAMP>, <SAMP>`r'</SAMP>, <SAMP>`t'</SAMP>, or <SAMP>`v'</SAMP>, -then the ANSI-C interpretation of <SAMP>`\x'</SAMP>. -Otherwise, a literal <SAMP>`X'</SAMP> (used to escape -operators such as <SAMP>`*'</SAMP>) +if X is <SAMP>`a'</SAMP>, <SAMP>`b'</SAMP>, <SAMP>`f'</SAMP>, <SAMP>`n'</SAMP>, <SAMP>`r'</SAMP>, <SAMP>`t'</SAMP>, or +<SAMP>`v'</SAMP>, then the ANSI-C interpretation of <SAMP>`\x'</SAMP>. Otherwise, a +literal <SAMP>`X'</SAMP> (used to escape operators such as <SAMP>`*'</SAMP>) -<A NAME="IDX40"></A> +<A NAME="IDX50"></A> <DT><SAMP>`\0'</SAMP> <DD> a NUL character (ASCII code 0) +<A NAME="IDX51"></A> <DT><SAMP>`\123'</SAMP> <DD> the character with octal value 123 @@ -566,75 +599,73 @@ <DT><SAMP>`(r)'</SAMP> <DD> -match an r; parentheses are used to override - precedence (see below) +match an <SAMP>`r'</SAMP>; parentheses are used to override precedence (see below) +<A NAME="IDX52"></A> <DT><SAMP>`rs'</SAMP> <DD> -the regular expression r followed by the -regular expression s; called <EM>concatenation</EM> +the regular expression <SAMP>`r'</SAMP> followed by the regular expression <SAMP>`s'</SAMP>; called +<EM>concatenation</EM> <DT><SAMP>`r|s'</SAMP> <DD> -either an r or an s +either an <SAMP>`r'</SAMP> or an <SAMP>`s'</SAMP> -<A NAME="IDX41"></A> +<A NAME="IDX53"></A> <DT><SAMP>`r/s'</SAMP> <DD> -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 type -of pattern is called <EM>trailing context</EM>. -(There are some combinations of r/s that flex -cannot match correctly. See section <A HREF="flex.html#SEC38">Limitations</A>, -regarding -dangerous trailing context.) +an <SAMP>`r'</SAMP> but only if it is followed by an <SAMP>`s'</SAMP>. The text matched by <SAMP>`s'</SAMP> 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 <SAMP>`r'</SAMP>. This type of pattern is called +<EM>trailing context</EM>. (There are some combinations of <SAMP>`r/s'</SAMP> that flex +cannot match correctly. See section <A HREF="flex.html#SEC52">Limitations</A>, regarding dangerous trailing +context.) -<A NAME="IDX42"></A> +<A NAME="IDX54"></A> +<A NAME="IDX55"></A> <DT><SAMP>`^r'</SAMP> <DD> -an r, but only at the beginning of a line (i.e., +an <SAMP>`r'</SAMP>, but only at the beginning of a line (i.e., when just starting to scan, or right after a newline has been scanned). -<A NAME="IDX43"></A> +<A NAME="IDX56"></A> +<A NAME="IDX57"></A> <DT><SAMP>`r$'</SAMP> <DD> -an r, but only at the end of a line (i.e., just -before a newline). Equivalent to <SAMP>`r/\n'</SAMP>. +an <SAMP>`r'</SAMP>, but only at the end of a line (i.e., just before a +newline). Equivalent to <SAMP>`r/\n'</SAMP>. +<A NAME="IDX58"></A> Note that <CODE>flex</CODE>'s notion of "newline" is exactly whatever the C compiler used to compile <CODE>flex</CODE> interprets <SAMP>`\n'</SAMP> as; in particular, on some DOS systems you must either filter out <SAMP>`\r'</SAMP>s in the input yourself, or explicitly use <SAMP>`r/\r\n'</SAMP> for <SAMP>`r$'</SAMP>. -<A NAME="IDX44"></A> +<A NAME="IDX59"></A> <DT><SAMP>`<s>r'</SAMP> <DD> -an r, but only in start condition s (see -section <A HREF="flex.html#SEC12">Start Conditions</A> for discussion of start conditions). +an <SAMP>`r'</SAMP>, but only in start condition <CODE>s</CODE> (see section <A HREF="flex.html#SEC14">Start Conditions</A> for discussion of start conditions). <DT><SAMP>`<s1,s2,s3>r'</SAMP> <DD> -same, but in any of start conditions s1, -s2, or s3. +same, but in any of start conditions <CODE>s1</CODE>, <CODE>s2</CODE>, or <CODE>s3</CODE>. <DT><SAMP>`<*>r'</SAMP> <DD> -an r in any start condition, even an exclusive one. +an <SAMP>`r'</SAMP> in any start condition, even an exclusive one. -<A NAME="IDX45"></A> +<A NAME="IDX60"></A> +<A NAME="IDX61"></A> <DT><SAMP>`<<EOF>>'</SAMP> <DD> an end-of-file. <DT><SAMP>`<s1,s2><<EOF>>'</SAMP> <DD> -an end-of-file when in start condition s1 or s2 +an end-of-file when in start condition <CODE>s1</CODE> or <CODE>s2</CODE> </DL> <P> @@ -644,7 +675,7 @@ <P> -<A NAME="IDX46"></A> +<A NAME="IDX62"></A> 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 @@ -653,7 +684,7 @@ <P> -<A NAME="IDX47"></A> +<A NAME="IDX63"></A> <PRE> @verbatim @@ -671,11 +702,11 @@ </PRE> <P> -since the '*' operator has higher precedence than concatenation, and -concatenation higher than alternation ('|'). This pattern therefore -matches <EM>either</EM> the string <SAMP>`foo'</SAMP> <EM>or</EM> the string -<SAMP>`ba'</SAMP> followed by zero-or-more r's. To match <SAMP>`foo'</SAMP> or -zero-or-more repetitions of the string <SAMP>`bar'</SAMP>, use: +since the <SAMP>`*'</SAMP> operator has higher precedence than concatenation, +and concatenation higher than alternation (<SAMP>`|'</SAMP>). This pattern +therefore matches <EM>either</EM> the string <SAMP>`foo'</SAMP> <EM>or</EM> the +string <SAMP>`ba'</SAMP> followed by zero-or-more <SAMP>`r'</SAMP>'s. To match +<SAMP>`foo'</SAMP> or zero-or-more repetitions of the string <SAMP>`bar'</SAMP>, use: @@ -690,7 +721,7 @@ <P> -<A NAME="IDX48"></A> +<A NAME="IDX64"></A> <PRE> @verbatim @@ -698,7 +729,7 @@ </PRE> <P> -<A NAME="IDX49"></A> +<A NAME="IDX65"></A> In addition to characters and ranges of characters, character classes can also contain <EM>character class expressions</EM>. These are expressions enclosed inside <SAMP>`['</SAMP>: and <SAMP>`:]'</SAMP> delimiters (which @@ -708,7 +739,7 @@ <P> -<A NAME="IDX50"></A> +<A NAME="IDX66"></A> <PRE> @verbatim @@ -719,19 +750,12 @@ </PRE> <P> -These expressions all designate a set of characters equivalent to -the corresponding standard C -<CODE>isXXX</CODE> -function. For example, -<SAMP>`[:alnum:]'</SAMP> -designates those characters for which -<CODE>isalnum()</CODE> -returns true - i.e., any alphabetic or numeric character. -Some systems don't provide -<CODE>isblank()</CODE>, -so flex defines -<SAMP>`[:blank:]'</SAMP> -as a blank or a tab. +These expressions all designate a set of characters equivalent to the +corresponding standard C <CODE>isXXX</CODE> function. For example, +<SAMP>`[:alnum:]'</SAMP> designates those characters for which <CODE>isalnum()</CODE> +returns true - i.e., any alphabetic or numeric character. Some systems +don't provide <CODE>isblank()</CODE>, so flex defines <SAMP>`[:blank:]'</SAMP> as a +blank or a tab. <P> @@ -739,8 +763,8 @@ <P> -<A NAME="IDX51"></A> -<A NAME="IDX52"></A> +<A NAME="IDX67"></A> +<A NAME="IDX68"></A> <PRE> @verbatim @@ -751,35 +775,35 @@ </PRE> <P> -<A NAME="IDX53"></A> +<A NAME="IDX69"></A> If your scanner is case-insensitive (the <SAMP>`-i'</SAMP> flag), then <SAMP>`[:upper:]'</SAMP> and <SAMP>`[:lower:]'</SAMP> are equivalent to <SAMP>`[:alpha:]'</SAMP>. <P> -Some notes on patterns: -<A NAME="IDX54"></A> -<A NAME="IDX55"></A> -<A NAME="IDX56"></A> -<A NAME="IDX57"></A> +Some notes on patterns are in order. <UL> <LI> -A negated character class such as the example <SAMP>`[^A-Z]'</SAMP> -above -<EM>will match a newline</EM> -unless <SAMP>`\n'</SAMP> (or an equivalent escape sequence) is one of the -characters explicitly present in the negated character class -(e.g., <SAMP>`[^A-Z\n]'</SAMP>). 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 <SAMP>`[^"]*'</SAMP> can match the entire +<A NAME="IDX70"></A> + <A NAME="IDX71"></A> + +A negated character class such as the example <SAMP>`[^A-Z]'</SAMP> above +<EM>will</EM> match a newline unless <SAMP>`\n'</SAMP> (or an equivalent escape +sequence) is one of the characters explicitly present in the negated +character class (e.g., <SAMP>`[^A-Z\n]'</SAMP>). 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 <SAMP>`[^"]*'</SAMP> can match the entire input unless there's another quote in the input. +<A NAME="IDX72"></A> +<A NAME="IDX73"></A> +<A NAME="IDX74"></A> <LI> A rule can have at most one instance of trailing context (the <SAMP>`/'</SAMP> operator @@ -793,7 +817,7 @@ The following are invalid: -<A NAME="IDX58"></A> +<A NAME="IDX75"></A> <PRE> @verbatim @@ -807,7 +831,7 @@ The following will result in <SAMP>`$'</SAMP> or <SAMP>`^'</SAMP> being treated as a normal character: -<A NAME="IDX59"></A> +<A NAME="IDX76"></A> <PRE> @verbatim @@ -817,9 +841,9 @@ If the desired meaning is a <SAMP>`foo'</SAMP> or a <SAMP>`bar'</SAMP>-followed-by-a-newline, the following could be used (the -special <CODE>|</CODE> action is explained below, see section <A HREF="flex.html#SEC10">Actions</A>): +special <CODE>|</CODE> action is explained below, see section <A HREF="flex.html#SEC12">Actions</A>): -<A NAME="IDX60"></A> +<A NAME="IDX77"></A> <PRE> @verbatim @@ -827,18 +851,21 @@ bar$ /* action goes here */ </PRE> -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 <SAMP>`foo'</SAMP> or a +<SAMP>`bar'</SAMP>-at-the-beginning-of-a-line. </UL> -<H1><A NAME="SEC9" HREF="flex_toc.html#TOC9">How the Input Is Matched</A></H1> -<P> -<A NAME="IDX61"></A> - +<H1><A NAME="SEC11" HREF="flex_toc.html#TOC11">How the Input Is Matched</A></H1> <P> +<A NAME="IDX78"></A> +<A NAME="IDX79"></A> +<A NAME="IDX80"></A> +<A NAME="IDX81"></A> +<A NAME="IDX82"></A> +<A NAME="IDX83"></A> When the generated scanner is run, it analyzes its input looking for 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 @@ -849,26 +876,26 @@ <P> +<A NAME="IDX84"></A> +<A NAME="IDX85"></A> +<A NAME="IDX86"></A> Once the match is determined, the text corresponding to the match (called the <EM>token</EM>) is made available in the global character -pointer <CODE>yytext</CODE>, and its length in the global integer <CODE>yyleng</CODE>. -The <EM>action</EM> corresponding to the matched pattern is then executed -(see section <A HREF="flex.html#SEC10">Actions</A>), and then the remaining input is scanned for another -match. +pointer <CODE>yytext</CODE>, and its length in the global integer +<CODE>yyleng</CODE>. The <EM>action</EM> corresponding to the matched pattern is +then executed (see section <A HREF="flex.html#SEC12">Actions</A>), and then the remaining input is scanned +for another match. <P> -<A NAME="IDX62"></A> -If no match is found, then the -<EM>default rule</EM> -is executed: the next character in the input is considered matched and -copied to the standard output. Thus, the simplest valid -<CODE>flex</CODE> -input is: +<A NAME="IDX87"></A> +If no match is found, then the <EM>default rule</EM> is executed: the next +character in the input is considered matched and copied to the standard +output. Thus, the simplest valid <CODE>flex</CODE> input is: <P> -<A NAME="IDX63"></A> +<A NAME="IDX88"></A> <PRE> @verbatim @@ -876,20 +903,17 @@ </PRE> <P> -which generates a scanner that simply copies its input (one character -at a time) to its output. - - -<P> -<A NAME="IDX64"></A> -<A NAME="IDX65"></A> -<A NAME="IDX66"></A> +which generates a scanner that simply copies its input (one character at +a time) to its output. <P> -<A NAME="IDX67"></A> -Note that <CODE>yytext</CODE> can be defined in two different ways: either as a -character <EM>pointer</EM> or as a character <EM>array</EM>. You can +<A NAME="IDX89"></A> +<A NAME="IDX90"></A> +<A NAME="IDX91"></A> +<A NAME="IDX92"></A> +Note that <CODE>yytext</CODE> can be defined in two different ways: either as +a character <EM>pointer</EM> or as a character <EM>array</EM>. You can control which definition <CODE>flex</CODE> uses by including one of the special directives <CODE>%pointer</CODE> or <CODE>%array</CODE> in the first (definitions) section of your flex input. The default is @@ -898,26 +922,19 @@ <CODE>%pointer</CODE> 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 <CODE>yytext</CODE> (see section <A HREF="flex.html#SEC10">Actions</A>), and calls to the <CODE>unput()</CODE> +modify <CODE>yytext</CODE> (see section <A HREF="flex.html#SEC12">Actions</A>), and calls to the <CODE>unput()</CODE> function destroys the present contents of <CODE>yytext</CODE>, which can be a considerable porting headache when moving between different <CODE>lex</CODE> versions. <P> -The advantage of -<CODE>%array</CODE> -is that you can then modify -<CODE>yytext</CODE> -to your heart's content, and calls to -<CODE>unput()</CODE> -do not destroy -<CODE>yytext</CODE> -(see section <A HREF="flex.html#SEC10">Actions</A>). Furthermore, existing -<CODE>lex</CODE> -programs sometimes access -<CODE>yytext</CODE> -externally using declarations of the form: +<A NAME="IDX93"></A> +The advantage of <CODE>%array</CODE> is that you can then modify <CODE>yytext</CODE> +to your heart's content, and calls to <CODE>unput()</CODE> do not destroy +<CODE>yytext</CODE> (see section <A HREF="flex.html#SEC12">Actions</A>). Furthermore, existing <CODE>lex</CODE> +programs sometimes access <CODE>yytext</CODE> externally using declarations of +the form: @@ -940,23 +957,23 @@ large tokens. While this means your <CODE>%pointer</CODE> scanner can accommodate very large tokens (such as matching entire blocks of comments), bear in mind that each time the scanner must resize -<CODE>yytext</CODE> it also must rescan the entire token from the beginning, so -matching such tokens can prove slow. <CODE>yytext</CODE> presently does +<CODE>yytext</CODE> it also must rescan the entire token from the beginning, +so matching such tokens can prove slow. <CODE>yytext</CODE> presently does <EM>not</EM> dynamically grow if a call to <CODE>unput()</CODE> results in too much text being pushed back; instead, a run-time error results. <P> -<A NAME="IDX68"></A> +<A NAME="IDX94"></A> Also note that you cannot use <CODE>%array</CODE> with C++ scanner classes -(see section <A HREF="flex.html#SEC21">Generating C++ Scanners</A>). +(see section <A HREF="flex.html#SEC28">Generating C++ Scanners</A>). -<H1><A NAME="SEC10" HREF="flex_toc.html#TOC10">Actions</A></H1> +<H1><A NAME="SEC12" HREF="flex_toc.html#TOC12">Actions</A></H1> <P> -<A NAME="IDX69"></A> +<A NAME="IDX95"></A> <P> @@ -969,7 +986,7 @@ <P> -<A NAME="IDX70"></A> +<A NAME="IDX96"></A> <PRE> @verbatim @@ -988,8 +1005,8 @@ <P> -<A NAME="IDX71"></A> -<A NAME="IDX72"></A> +<A NAME="IDX97"></A> +<A NAME="IDX98"></A> <PRE> @verbatim @@ -999,11 +1016,11 @@ </PRE> <P> -<A NAME="IDX73"></A> -<A NAME="IDX74"></A> -<A NAME="IDX75"></A> -<A NAME="IDX76"></A> -<A NAME="IDX77"></A> +<A NAME="IDX99"></A> +<A NAME="IDX100"></A> +<A NAME="IDX101"></A> +<A NAME="IDX102"></A> +<A NAME="IDX103"></A> <P> @@ -1032,17 +1049,17 @@ <P> -<A NAME="IDX78"></A> +<A NAME="IDX104"></A> Actions are free to modify <CODE>yytext</CODE> 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 <CODE>%array</CODE> -(see section <A HREF="flex.html#SEC9">How the Input Is Matched</A>). In that case, <CODE>yytext</CODE> may be freely modified in +(see section <A HREF="flex.html#SEC11">How the Input Is Matched</A>). In that case, <CODE>yytext</CODE> may be freely modified in any way. <P> -<A NAME="IDX79"></A> -<A NAME="IDX80"></A> +<A NAME="IDX105"></A> +<A NAME="IDX106"></A> Actions are free to modify <CODE>yyleng</CODE> except they should not do so if the action also includes use of @@ -1051,7 +1068,7 @@ <P> -<A NAME="IDX81"></A> +<A NAME="IDX107"></A> <P> @@ -1063,30 +1080,30 @@ <DT><CODE>ECHO</CODE> <DD> -<A NAME="IDX82"></A> +<A NAME="IDX108"></A> copies yytext to the scanner's output. -<A NAME="IDX83"></A> +<A NAME="IDX109"></A> <DT><CODE>BEGIN</CODE> <DD> followed by the name of a start condition places the scanner in the corresponding start condition (see below). -<A NAME="IDX84"></A> +<A NAME="IDX110"></A> <DT><CODE>REJECT</CODE> <DD> 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 section <A HREF="flex.html#SEC9">How the Input Is Matched</A>, and <CODE>yytext</CODE> and <CODE>yyleng</CODE> set +described above in section <A HREF="flex.html#SEC11">How the Input Is Matched</A>, and <CODE>yytext</CODE> and <CODE>yyleng</CODE> set up appropriately. It may either be one which matched as much text as the originally chosen rule but came later in the <CODE>flex</CODE> input file, or one which matched less text. For example, the following will both count the words in the input and call the routine <CODE>special()</CODE> whenever <SAMP>`frob'</SAMP> is seen: -<A NAME="IDX85"></A> -<A NAME="IDX86"></A> +<A NAME="IDX111"></A> +<A NAME="IDX112"></A> <PRE> @verbatim @@ -1104,7 +1121,7 @@ example, when the following scanner scans the token <SAMP>`abcd'</SAMP>, it will write <SAMP>`abcdabcaba'</SAMP> to the output: -<A NAME="IDX87"></A> +<A NAME="IDX113"></A> <PRE> @verbatim @@ -1130,13 +1147,13 @@ <SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP> -options (see section <A HREF="flex.html#SEC18">Invoking Flex</A>). +options (see section <A HREF="flex.html#SEC20">Scanner Options</A>). Note also that unlike the other special actions, <CODE>REJECT</CODE> is a <EM>branch</EM>. code immediately following it in the action will <EM>not</EM> be executed. -<A NAME="IDX88"></A> +<A NAME="IDX114"></A> <DT><CODE>yymore()</CODE> <DD> tells the scanner that the next time it matches a rule, the @@ -1145,8 +1162,8 @@ <SAMP>`mega-kludge'</SAMP> the following will write <SAMP>`mega-mega-kludge'</SAMP> to the output: -<A NAME="IDX89"></A> -<A NAME="IDX90"></A> +<A NAME="IDX115"></A> +<A NAME="IDX116"></A> <PRE> @verbatim @@ -1174,7 +1191,7 @@ <P> -<A NAME="IDX91"></A> +<A NAME="IDX117"></A> <CODE>yyless(n)</CODE> returns all but the first <CODE>n</CODE> characters of the current token back to the input stream, where they will be rescanned when the scanner looks for the next match. <CODE>yytext</CODE> and @@ -1184,9 +1201,9 @@ <P> -<A NAME="IDX92"></A> -<A NAME="IDX93"></A> -<A NAME="IDX94"></A> +<A NAME="IDX118"></A> +<A NAME="IDX119"></A> +<A NAME="IDX120"></A> <PRE> @verbatim @@ -1212,8 +1229,8 @@ <P> -<A NAME="IDX95"></A> -<A NAME="IDX96"></A> +<A NAME="IDX121"></A> +<A NAME="IDX122"></A> <CODE>unput(c)</CODE> puts the character <CODE>c</CODE> @@ -1223,7 +1240,7 @@ <P> -<A NAME="IDX97"></A> +<A NAME="IDX123"></A> <PRE> @verbatim @@ -1246,8 +1263,8 @@ <P> -<A NAME="IDX98"></A> -<A NAME="IDX99"></A> +<A NAME="IDX124"></A> +<A NAME="IDX125"></A> <P> @@ -1267,25 +1284,25 @@ (as in the above example), you must either first copy it elsewhere, or build your scanner using <CODE>%array</CODE> -instead (see section <A HREF="flex.html#SEC9">How the Input Is Matched</A>). +instead (see section <A HREF="flex.html#SEC11">How the Input Is Matched</A>). <P> -<A NAME="IDX100"></A> -<A NAME="IDX101"></A> +<A NAME="IDX126"></A> +<A NAME="IDX127"></A> Finally, note that you cannot put back <SAMP>`EOF'</SAMP> to attempt to mark the input stream with an end-of-file. <P> -<A NAME="IDX102"></A> +<A NAME="IDX128"></A> <CODE>input()</CODE> reads the next character from the input stream. For example, the following is one way to eat up C comments: <P> -<A NAME="IDX103"></A> -<A NAME="IDX104"></A> +<A NAME="IDX129"></A> +<A NAME="IDX130"></A> <PRE> @verbatim @@ -1317,7 +1334,7 @@ </PRE> <P> -<A NAME="IDX105"></A> +<A NAME="IDX131"></A> (Note that if the scanner is compiled using <CODE>C++</CODE>, then <CODE>input()</CODE> is instead referred to as <B>yyinput()</B>, in order to avoid a name clash with the <CODE>C++</CODE> stream by the name of @@ -1325,24 +1342,24 @@ <P> -<A NAME="IDX106"></A> +<A NAME="IDX132"></A> <CODE>YY_FLUSH_BUFFER()</CODE> 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 <CODE>YY_INPUT()</CODE> -(see section <A HREF="flex.html#SEC11">The Generated Scanner</A>). This action is a special case +(see section <A HREF="flex.html#SEC13">The Generated Scanner</A>). This action is a special case of the more general <CODE>yy_flush_buffer()</CODE> -function, described below (see section <A HREF="flex.html#SEC13">Multiple Input Buffers</A>) +function, described below (see section <A HREF="flex.html#SEC15">Multiple Input Buffers</A>) <P> -<A NAME="IDX107"></A> -<A NAME="IDX108"></A> -<A NAME="IDX109"></A> -<A NAME="IDX110"></A> -<A NAME="IDX111"></A> +<A NAME="IDX133"></A> +<A NAME="IDX134"></A> +<A NAME="IDX135"></A> +<A NAME="IDX136"></A> +<A NAME="IDX137"></A> <P> @@ -1357,10 +1374,10 @@ -<H1><A NAME="SEC11" HREF="flex_toc.html#TOC11">The Generated Scanner</A></H1> +<H1><A NAME="SEC13" HREF="flex_toc.html#TOC13">The Generated Scanner</A></H1> <P> -<A NAME="IDX112"></A> +<A NAME="IDX138"></A> The output of <CODE>flex</CODE> is the file <TT>`lex.yy.c'</TT>, which contains the scanning routine <CODE>yylex()</CODE>, a number of tables used by it for matching tokens, and a number of auxiliary routines and macros. By @@ -1377,7 +1394,7 @@ </PRE> <P> -<A NAME="IDX113"></A> +<A NAME="IDX139"></A> (If your environment supports function prototypes, then it will be <CODE>int yylex( void )</CODE>.) This definition may be changed by defining @@ -1385,7 +1402,7 @@ <P> -<A NAME="IDX114"></A> +<A NAME="IDX140"></A> <PRE> @verbatim @@ -1400,7 +1417,19 @@ <P> -<A NAME="IDX115"></A> +<CODE>flex</CODE> generates <SAMP>`C99'</SAMP> function definitions by default. However flex +does have the ability to generate obsolete, er, <SAMP>`traditional'</SAMP>, 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 <CODE>flex</CODE> may generate standard C99 code +only, leaving K&R-style functions to the historians. Currently, if you do +<STRONG>not</STRONG> want <SAMP>`C99'</SAMP> definitions, then you must define +<CODE>YY_TRADITIONAL_FUNC_DEFS</CODE>. + + +<P> +<A NAME="IDX141"></A> Whenever <CODE>yylex()</CODE> is called, it scans tokens from the global input file <TT>`yyin'</TT> (which defaults to stdin). It continues until it either reaches an end-of-file (at which point it returns the value 0) or @@ -1408,7 +1437,7 @@ <P> -<A NAME="IDX116"></A> +<A NAME="IDX142"></A> If the scanner reaches an end-of-file, subsequent calls are undefined unless either <TT>`yyin'</TT> is pointed at a new input file (in which case scanning continues from that file), or <CODE>yyrestart()</CODE> is called. @@ -1421,13 +1450,13 @@ <CODE>flex</CODE>, 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 <TT>`yyin'</TT>; but it would be -better to use <CODE>YY_FLUSH_BUFFER</CODE> (see section <A HREF="flex.html#SEC10">Actions</A>). Note that +better to use <CODE>YY_FLUSH_BUFFER</CODE> (see section <A HREF="flex.html#SEC12">Actions</A>). Note that <CODE>yyrestart()</CODE> does <EM>not</EM> reset the start condition to -<CODE>INITIAL</CODE> (see section <A HREF="flex.html#SEC12">Start Conditions</A>). +<CODE>INITIAL</CODE> (see section <A HREF="flex.html#SEC14">Start Conditions</A>). <P> -<A NAME="IDX117"></A> +<A NAME="IDX143"></A> If <CODE>yylex()</CODE> stops scanning due to executing a @@ -1450,13 +1479,13 @@ <P> -<A NAME="IDX118"></A> +<A NAME="IDX144"></A> Here is a sample definition of <CODE>YY_INPUT</CODE> (in the definitions section of the input file): <P> -<A NAME="IDX119"></A> +<A NAME="IDX145"></A> <PRE> @verbatim @@ -1475,7 +1504,7 @@ <P> -<A NAME="IDX120"></A> +<A NAME="IDX146"></A> When the scanner receives an end-of-file indication from YY_INPUT, it then checks the <CODE>yywrap()</CODE> function. If <CODE>yywrap()</CODE> returns false (zero), then it is assumed that the function has gone ahead and @@ -1496,7 +1525,7 @@ <P> For scanning from in-memory buffers (e.g., scanning strings), see @xref{Scanning Strings} -See section <A HREF="flex.html#SEC13">Multiple Input Buffers</A>. +See section <A HREF="flex.html#SEC15">Multiple Input Buffers</A>. <P> @@ -1512,10 +1541,10 @@ -<H1><A NAME="SEC12" HREF="flex_toc.html#TOC12">Start Conditions</A></H1> +<H1><A NAME="SEC14" HREF="flex_toc.html#TOC14">Start Conditions</A></H1> <P> -<A NAME="IDX121"></A> +<A NAME="IDX147"></A> <CODE>flex</CODE> provides a mechanism for conditionally activating rules. Any rule whose pattern is prefixed with <SAMP>`<sc>'</SAMP> will only be active when @@ -1523,7 +1552,7 @@ <P> -<A NAME="IDX122"></A> +<A NAME="IDX148"></A> <PRE> @verbatim @@ -1538,7 +1567,7 @@ <P> -<A NAME="IDX123"></A> +<A NAME="IDX149"></A> <PRE> @verbatim @@ -1553,7 +1582,7 @@ <P> -<A NAME="IDX124"></A> +<A NAME="IDX150"></A> Start conditions are declared in the definitions (first) section of the input using unindented lines beginning with either <SAMP>`%s'</SAMP> or <SAMP>`%x'</SAMP> followed by a list of names. The former declares @@ -1579,7 +1608,7 @@ <P> -<A NAME="IDX125"></A> +<A NAME="IDX151"></A> <PRE> @verbatim @@ -1596,7 +1625,7 @@ <P> -<A NAME="IDX126"></A> +<A NAME="IDX152"></A> <PRE> @verbatim @@ -1619,7 +1648,7 @@ <P> -<A NAME="IDX127"></A> +<A NAME="IDX153"></A> Also note that the special start-condition specifier <CODE><*></CODE> matches every start condition. Thus, the above example could also @@ -1627,7 +1656,7 @@ <P> -<A NAME="IDX128"></A> +<A NAME="IDX154"></A> <PRE> @verbatim @@ -1645,7 +1674,7 @@ <P> -<A NAME="IDX129"></A> +<A NAME="IDX155"></A> <PRE> @verbatim @@ -1653,9 +1682,9 @@ </PRE> <P> -<A NAME="IDX130"></A> -<A NAME="IDX131"></A> -<A NAME="IDX132"></A> +<A NAME="IDX156"></A> +<A NAME="IDX157"></A> +<A NAME="IDX158"></A> <CODE>BEGIN(0)</CODE> 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 <CODE>INITIAL</CODE>, so <CODE>BEGIN(INITIAL)</CODE> is @@ -1671,7 +1700,7 @@ <P> -<A NAME="IDX133"></A> +<A NAME="IDX159"></A> <PRE> @verbatim @@ -1696,7 +1725,7 @@ <P> -<A NAME="IDX134"></A> +<A NAME="IDX160"></A> <PRE> @verbatim @@ -1730,13 +1759,13 @@ </PRE> <P> -<A NAME="IDX135"></A> +<A NAME="IDX161"></A> Here is a scanner which recognizes (and discards) C comments while maintaining a count of the current input line. <P> -<A NAME="IDX136"></A> +<A NAME="IDX162"></A> <PRE> @verbatim @@ -1766,8 +1795,8 @@ <P> -<A NAME="IDX137"></A> -<A NAME="IDX138"></A> +<A NAME="IDX163"></A> +<A NAME="IDX164"></A> <PRE> @verbatim @@ -1795,14 +1824,14 @@ </PRE> <P> -<A NAME="IDX139"></A> +<A NAME="IDX165"></A> Furthermore, you can access the current start condition using the integer-valued <CODE>YY_START</CODE> macro. For example, the above assignments to <CODE>comment_caller</CODE> could instead be written <P> -<A NAME="IDX140"></A> +<A NAME="IDX166"></A> <PRE> @verbatim @@ -1810,14 +1839,16 @@ </PRE> <P> -<A NAME="IDX141"></A> +<A NAME="IDX167"></A> Flex provides <CODE>YYSTATE</CODE> as an alias for <CODE>YY_START</CODE> (since that is what's used by AT&T <CODE>lex</CODE>). <P> -Note that start conditions do not have their own name-space; %s's and %x's -declare names in the same fashion as #define's. +For historical reasons, start conditions do not have their own +name-space within the generated scanner. The start condition names are +unmodified in the generated scanner and generated header. +@xref{option-header}. @xref{option-prefix}. <P> @@ -1827,7 +1858,7 @@ <P> -<A NAME="IDX142"></A> +<A NAME="IDX168"></A> <PRE> @verbatim @@ -1887,7 +1918,7 @@ </PRE> <P> -<A NAME="IDX143"></A> +<A NAME="IDX169"></A> Often, such as in some of the examples above, you wind up writing a whole bunch of rules all preceded by the same start condition(s). Flex makes this a little easier and cleaner by introducing a notion of start @@ -1908,7 +1939,7 @@ <P> -<A NAME="IDX144"></A> +<A NAME="IDX170"></A> <PRE> @verbatim @@ -1938,8 +1969,8 @@ <P> -<A NAME="IDX145"></A> -<A NAME="IDX146"></A> +<A NAME="IDX171"></A> +<A NAME="IDX172"></A> <P> @@ -1949,7 +1980,7 @@ <P> <DL> <DT><U>Function:</U> void <B>yy_push_state</B> <I>( int <CODE>new_state</CODE> )</I> -<DD><A NAME="IDX147"></A> +<DD><A NAME="IDX173"></A> pushes the current start condition onto the top of the start condition stack and switches to <CODE>new_state</CODE> @@ -1962,7 +1993,7 @@ <P> <DL> <DT><U>Function:</U> void <B>yy_pop_state</B> <I>()</I> -<DD><A NAME="IDX148"></A> +<DD><A NAME="IDX174"></A> pops the top of the stack and switches to it via <CODE>BEGIN</CODE>. </DL> @@ -1971,28 +2002,28 @@ <P> <DL> <DT><U>Function:</U> int <B>yy_top_state</B> <I>()</I> -<DD><A NAME="IDX149"></A> +<DD><A NAME="IDX175"></A> returns the top of the stack without altering the stack's contents. </DL> <P> -<A NAME="IDX150"></A> +<A NAME="IDX176"></A> The start condition stack grows dynamically and so has no built-in size limitation. If memory is exhausted, program execution aborts. <P> To use start condition stacks, your scanner must include a <CODE>%option -stack</CODE> directive (see section <A HREF="flex.html#SEC18">Invoking Flex</A>). +stack</CODE> directive (see section <A HREF="flex.html#SEC20">Scanner Options</A>). -<H1><A NAME="SEC13" HREF="flex_toc.html#TOC13">Multiple Input Buffers</A></H1> +<H1><A NAME="SEC15" HREF="flex_toc.html#TOC15">Multiple Input Buffers</A></H1> <P> -<A NAME="IDX151"></A> +<A NAME="IDX177"></A> Some scanners (such as those which support "include" files) require reading from several input streams. As <CODE>flex</CODE> scanners do a large amount of buffering, one cannot control where the next input will be @@ -2010,10 +2041,10 @@ <P> -<A NAME="IDX152"></A> +<A NAME="IDX178"></A> <DL> <DT><U>Function:</U> YY_BUFFER_STATE <B>yy_create_buffer</B> <I>( FILE *file, int size )</I> -<DD><A NAME="IDX153"></A> +<DD><A NAME="IDX179"></A> </DL> @@ -2022,8 +2053,8 @@ associated with the given file and large enough to hold <CODE>size</CODE> characters (when in doubt, use <CODE>YY_BUF_SIZE</CODE> for the size). It returns a <CODE>YY_BUFFER_STATE</CODE> handle, which may then be passed to -other routines (see below). -<A NAME="IDX154"></A> +other routines (see below). +<A NAME="IDX180"></A> The <CODE>YY_BUFFER_STATE</CODE> type is a pointer to an opaque <CODE>struct yy_buffer_state</CODE> structure, so you may safely initialize <CODE>YY_BUFFER_STATE</CODE> variables to <CODE>((YY_BUFFER_STATE) @@ -2040,7 +2071,7 @@ <P> <DL> <DT><U>Function:</U> void <B>yy_switch_to_buffer</B> <I>( YY_BUFFER_STATE new_buffer )</I> -<DD><A NAME="IDX155"></A> +<DD><A NAME="IDX181"></A> </DL> @@ -2054,10 +2085,10 @@ <P> -<A NAME="IDX156"></A> +<A NAME="IDX182"></A> <DL> <DT><U>Function:</U> void <B>yy_delete_buffer</B> <I>( YY_BUFFER_STATE buffer )</I> -<DD><A NAME="IDX157"></A> +<DD><A NAME="IDX183"></A> </DL> @@ -2068,11 +2099,11 @@ <P> -<A NAME="IDX158"></A> -<A NAME="IDX159"></A> +<A NAME="IDX184"></A> +<A NAME="IDX185"></A> <DL> <DT><U>Function:</U> void <B>yy_flush_buffer</B> <I>( YY_BUFFER_STATE buffer )</I> -<DD><A NAME="IDX160"></A> +<DD><A NAME="IDX186"></A> </DL> @@ -2086,7 +2117,7 @@ <P> <DL> <DT><U>Function:</U> YY_BUFFER_STATE <B>yy_new_buffer</B> <I>( FILE *file, int size )</I> -<DD><A NAME="IDX161"></A> +<DD><A NAME="IDX187"></A> </DL> @@ -2097,13 +2128,13 @@ <P> -<A NAME="IDX162"></A> +<A NAME="IDX188"></A> Finally, the macro <CODE>YY_CURRENT_BUFFER</CODE> macro returns a <CODE>YY_BUFFER_STATE</CODE> handle to the current buffer. <P> -<A NAME="IDX163"></A> +<A NAME="IDX189"></A> Here is an example of using these features for writing a scanner which expands include files (the <CODE><<EOF>></CODE> @@ -2111,7 +2142,7 @@ <P> -<A NAME="IDX164"></A> +<A NAME="IDX190"></A> <PRE> @verbatim @@ -2171,7 +2202,7 @@ <P> @anchor{Scanning Strings} -<A NAME="IDX165"></A> +<A NAME="IDX191"></A> 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 @@ -2184,7 +2215,7 @@ <P> <DL> <DT><U>Function:</U> YY_BUFFER_STATE <B>yy_scan_string</B> <I>( const char *str )</I> -<DD><A NAME="IDX166"></A> +<DD><A NAME="IDX192"></A> scans a NUL-terminated string. </DL> @@ -2192,7 +2223,7 @@ <P> <DL> <DT><U>Function:</U> YY_BUFFER_STATE <B>yy_scan_bytes</B> <I>( const char *bytes, int len )</I> -<DD><A NAME="IDX167"></A> +<DD><A NAME="IDX193"></A> scans <CODE>len</CODE> bytes (including possibly <CODE>NUL</CODE>s) starting at location <CODE>bytes</CODE>. </DL> @@ -2206,10 +2237,10 @@ <P> -<A NAME="IDX168"></A> +<A NAME="IDX194"></A> <DL> <DT><U>Function:</U> YY_BUFFER_STATE <B>yy_scan_buffer</B> <I>(char *base, yy_size_t size)</I> -<DD><A NAME="IDX169"></A> +<DD><A NAME="IDX195"></A> which scans in place the buffer starting at <CODE>base</CODE>, consisting of <CODE>size</CODE> bytes, the last two bytes of which <EM>must</EM> be <CODE>YY_END_OF_BUFFER_CHAR</CODE> (ASCII NUL). These last two bytes are not @@ -2227,7 +2258,7 @@ <P> <DL> <DT><U>Data type:</U> <B>yy_size_t</B> -<DD><A NAME="IDX170"></A> +<DD><A NAME="IDX196"></A> is an integral type to which you can cast an integer expression reflecting the size of the buffer. </DL> @@ -2235,10 +2266,10 @@ -<H1><A NAME="SEC14" HREF="flex_toc.html#TOC14">End-of-File Rules</A></H1> +<H1><A NAME="SEC16" HREF="flex_toc.html#TOC16">End-of-File Rules</A></H1> <P> -<A NAME="IDX171"></A> +<A NAME="IDX197"></A> The special rule <CODE><<EOF>></CODE> indicates actions which are to be taken when an end-of-file is encountered and <CODE>yywrap()</CODE> returns non-zero (i.e., indicates @@ -2250,7 +2281,7 @@ <UL> <LI> -<A NAME="IDX172"></A> +<A NAME="IDX198"></A> assigning <TT>`yyin'</TT> to a new input file (in previous versions of <CODE>flex</CODE>, after doing the assignment you had to call the special action <CODE>YY_NEW_FILE</CODE>. This is no longer necessary.) @@ -2289,7 +2320,7 @@ <P> -<A NAME="IDX173"></A> +<A NAME="IDX199"></A> <PRE> @verbatim @@ -2312,10 +2343,10 @@ -<H1><A NAME="SEC15" HREF="flex_toc.html#TOC15">Miscellaneous Macros</A></H1> +<H1><A NAME="SEC17" HREF="flex_toc.html#TOC17">Miscellaneous Macros</A></H1> <P> -<A NAME="IDX174"></A> +<A NAME="IDX200"></A> The macro <CODE>YY_USER_ACTION</CODE> 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 @@ -2326,7 +2357,7 @@ <P> -<A NAME="IDX175"></A> +<A NAME="IDX201"></A> <PRE> @verbatim @@ -2334,7 +2365,7 @@ </PRE> <P> -<A NAME="IDX176"></A> +<A NAME="IDX202"></A> where <CODE>ctr</CODE> is an array to hold the counts for the different rules. Note that the macro <CODE>YY_NUM_RULES</CODE> gives the total number of rules (including the default rule), even if you use <SAMP>`-s)'</SAMP>, so a correct @@ -2348,7 +2379,7 @@ </PRE> <P> -<A NAME="IDX177"></A> +<A NAME="IDX203"></A> The macro <CODE>YY_USER_INIT</CODE> 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 @@ -2356,23 +2387,23 @@ <P> -<A NAME="IDX178"></A> +<A NAME="IDX204"></A> The macro <CODE>yy_set_interactive(is_interactive)</CODE> can be used to control whether the current buffer is considered <EM>interactive</EM>. 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 <SAMP>`-I'</SAMP> flag in -section <A HREF="flex.html#SEC18">Invoking Flex</A>). A non-zero value in the macro invocation marks +section <A HREF="flex.html#SEC20">Scanner Options</A>). 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 <CODE>%option always-interactive</CODE> or -<CODE>%option never-interactive</CODE> (see section <A HREF="flex.html#SEC18">Invoking Flex</A>). +<CODE>%option never-interactive</CODE> (see section <A HREF="flex.html#SEC20">Scanner Options</A>). <CODE>yy_set_interactive()</CODE> must be invoked prior to beginning to scan the buffer that is (or is not) to be considered interactive. <P> -<A NAME="IDX179"></A> -<A NAME="IDX180"></A> +<A NAME="IDX205"></A> +<A NAME="IDX206"></A> The macro <CODE>yy_set_bol(at_bol)</CODE> 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 @@ -2381,15 +2412,15 @@ <P> -<A NAME="IDX181"></A> -<A NAME="IDX182"></A> +<A NAME="IDX207"></A> +<A NAME="IDX208"></A> The macro <CODE>YY_AT_BOL()</CODE> returns true if the next token scanned from the current buffer will have <SAMP>`^'</SAMP> rules active, false otherwise. <P> -<A NAME="IDX183"></A> -<A NAME="IDX184"></A> +<A NAME="IDX209"></A> +<A NAME="IDX210"></A> In the generated scanner, the actions are all gathered in one large switch statement and separated using <CODE>YY_BREAK</CODE>, which may be redefined. By default, it is simply a <CODE>break</CODE>, to separate each @@ -2403,7 +2434,7 @@ -<H1><A NAME="SEC16" HREF="flex_toc.html#TOC16">Values Available To the User</A></H1> +<H1><A NAME="SEC18" HREF="flex_toc.html#TOC18">Values Available To the User</A></H1> <P> This chapter summarizes the various values available to the user in the @@ -2414,14 +2445,14 @@ <DT><CODE>char *yytext</CODE> <DD> -<A NAME="IDX185"></A> +<A NAME="IDX211"></A> holds the text of the current token. It may be modified but not lengthened (you cannot append characters to the end). -<A NAME="IDX186"></A> -<A NAME="IDX187"></A> -<A NAME="IDX188"></A> +<A NAME="IDX212"></A> +<A NAME="IDX213"></A> +<A NAME="IDX214"></A> If the special directive <CODE>%array</CODE> appears in the first section of the scanner description, then <CODE>yytext</CODE> is instead declared <CODE>char yytext[YYLMAX]</CODE>, where <CODE>YYLMAX</CODE> is a macro definition @@ -2432,16 +2463,16 @@ a character pointer. The opposite of <CODE>%array</CODE> is <CODE>%pointer</CODE>, which is the default. -<A NAME="IDX189"></A> +<A NAME="IDX215"></A> You cannot use <CODE>%array</CODE> when generating C++ scanner classes (the <SAMP>`-+'</SAMP> flag). -<A NAME="IDX190"></A> +<A NAME="IDX216"></A> <DT><CODE>int yyleng</CODE> <DD> holds the length of the current token. -<A NAME="IDX191"></A> +<A NAME="IDX217"></A> <DT><CODE>FILE *yyin</CODE> <DD> is the file which by default <CODE>flex</CODE> reads from. It may be @@ -2452,7 +2483,7 @@ end-of-file has been seen, you can assign <TT>`yyin'</TT> at the new input file and then call the scanner again to continue scanning. -<A NAME="IDX192"></A> +<A NAME="IDX218"></A> <DT><CODE>void yyrestart( FILE *new_file )</CODE> <DD> may be called to point <TT>`yyin'</TT> at the new input file. The @@ -2461,18 +2492,18 @@ as an argument thus throws away the current input buffer and continues scanning the same input file. -<A NAME="IDX193"></A> +<A NAME="IDX219"></A> <DT><CODE>FILE *yyout</CODE> <DD> is the file to which <CODE>ECHO</CODE> actions are done. It can be reassigned by the user. -<A NAME="IDX194"></A> +<A NAME="IDX220"></A> <DT><CODE>YY_CURRENT_BUFFER</CODE> <DD> returns a <CODE>YY_BUFFER_STATE</CODE> handle to the current buffer. -<A NAME="IDX195"></A> +<A NAME="IDX221"></A> <DT><CODE>YY_START</CODE> <DD> returns an integer value corresponding to the current start condition. @@ -2482,14 +2513,14 @@ -<H1><A NAME="SEC17" HREF="flex_toc.html#TOC17">Interfacing with Yacc</A></H1> +<H1><A NAME="SEC19" HREF="flex_toc.html#TOC19">Interfacing with Yacc</A></H1> <P> -<A NAME="IDX196"></A> +<A NAME="IDX222"></A> <P> -<A NAME="IDX197"></A> +<A NAME="IDX223"></A> One of the main uses of <CODE>flex</CODE> is as a companion to the <CODE>yacc</CODE> parser-generator. <CODE>yacc</CODE> parsers expect to call a routine named <CODE>yylex()</CODE> to find the next input token. The routine is supposed to @@ -2503,7 +2534,7 @@ <P> -<A NAME="IDX198"></A> +<A NAME="IDX224"></A> <PRE> @verbatim @@ -2518,138 +2549,203 @@ -<H1><A NAME="SEC18" HREF="flex_toc.html#TOC18">Invoking Flex</A></H1> +<H1><A NAME="SEC20" HREF="flex_toc.html#TOC20">Scanner Options</A></H1> <P> -<A NAME="IDX199"></A> -<A NAME="IDX200"></A> -<A NAME="IDX201"></A> +<A NAME="IDX225"></A> +<A NAME="IDX226"></A> +<A NAME="IDX227"></A> <P> -<CODE>flex</CODE> -has the following options. +The various <CODE>flex</CODE> options are categorized by function in the following +menu. If you want to lookup a particular option by name, See section <A HREF="flex.html#SEC163">Index of Scanner Options</A>. -<DL COMPACT> +<P> +Even though there are many scanner options, a typical scanner might only +specify the following options: -<DT><SAMP>`-b, --backup'</SAMP> -<DD> -Generate backing-up information to <TT>`lex.backup'</TT>. 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 -<EM>all</EM> backing-up states are eliminated and <SAMP>`-Cf'</SAMP> or <CODE>-CF</CODE> -is used, the generated scanner will run faster (see the <SAMP>`--perf-report'</SAMP> flag). -Only users who wish to squeeze every last cycle out of their scanners -need worry about this option. (see section <A HREF="flex.html#SEC20">Performance Considerations</A>). -<DT><SAMP>`-c'</SAMP> -<DD> -is a do-nothing option included for POSIX compliance. -<DT><SAMP>`-d, --debug'</SAMP> -<DD> -makes the generated scanner run in <EM>debug</EM> mode. Whenever a pattern -is recognized and the global variable <CODE>yy_flex_debug</CODE> is non-zero -(which is the default), the scanner will write to <TT>`stderr'</TT> a line -of the form: +<PRE> +@verbatim +%option 8-bit reentrant bison-bridge +%option warn nodefault +%option yylineno +%option outfile="scanner.c" header-file="scanner.h" +</PRE> + +<P> +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 dividied them.) + + +<P> +<CODE>flex</CODE> also provides a mechanism for controlling options within the +scanner specification itself, rather than from the flex command-line. +This is done by including <CODE>%option</CODE> directives in the first section +of the scanner specification. You can specify multiple options with a +single <CODE>%option</CODE> directive, and multiple directives in the first +section of your flex input file. + + +<P> +Most options are given simply as names, optionally preceded by the +word <SAMP>`no'</SAMP> (with no intervening whitespace) to negate their meaning. +The names are the same as their long-option equivalents (but without the +leading <SAMP>`--'</SAMP> ). + + +<P> +<CODE>flex</CODE> scans your rule actions to determine whether you use the +<CODE>REJECT</CODE> or <CODE>yymore()</CODE> features. The <CODE>REJECT</CODE> and +<CODE>yymore</CODE> options are available to override its decision as to +whether you use the options, either by setting them (e.g., <CODE>%option +reject)</CODE> to indicate the feature is indeed used, or unsetting them to +indicate it actually is not used (e.g., <CODE>%option noyymore)</CODE>. + + +<P> +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., <CODE>%option nounput</CODE>), results in the +corresponding routine not appearing in the generated scanner: + <PRE> @verbatim - -accepting rule at line 53 ("the matched text") + input, unput + yy_push_state, yy_pop_state, yy_top_state + yy_scan_buffer, yy_scan_bytes, yy_scan_string + + yyget_extra, yyset_extra, yyget_leng, yyget_text, + yyget_lineno, yyset_lineno, yyget_in, yyset_in, + yyget_out, yyset_out, yyget_lval, yyset_lval, + yyget_lloc, yyset_lloc, yyget_debug, yyset_debug </PRE> -The line number refers to the location of the rule in the file defining -the scanner (i.e., the file that was fed to flex). Messages are also -generated when the scanner backs up, accepts the default rule, reaches -the end of its input buffer (or encounters a NUL; at this point, the two -look the same as far as the scanner's concerned), or reaches an -end-of-file. +<P> +(though <CODE>yy_push_state()</CODE> and friends won't appear anyway unless +you use <CODE>%option stack)</CODE>. -<DT><SAMP>`-f, --full'</SAMP> -<DD> -specifies -<EM>fast scanner</EM>. -No table compression is done and <CODE>stdio</CODE> is bypassed. -The result is large but fast. This option is equivalent to -<SAMP>`--Cfr'</SAMP> -<DT><SAMP>`-h, -?, --help'</SAMP> -<DD> -generates a "help" summary of <CODE>flex</CODE>'s options to <TT>`stdout'</TT> -and then exits. -<DT><SAMP>`--header=FILE'</SAMP> + +<H2><A NAME="SEC21" HREF="flex_toc.html#TOC21">Options for Specifing Filenames</A></H2> + +<DL COMPACT> + +@anchor{option-header} +<DT><SAMP>`--header-file=FILE, <CODE>%option header-file="FILE"</CODE>'</SAMP> <DD> +<A NAME="IDX228"></A> + <A NAME="IDX229"></A> + instructs flex to write a C header to <TT>`FILE'</TT>. This file contains -function prototypes, extern variables, and macros used by the scanner. -It is meant to be included in other C files to avoid compiler warnings. -The <SAMP>`--header'</SAMP> option is not compatible with the <SAMP>`--c++'</SAMP> option, +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 the goal of a clean +external API. + +While in the header, the macro <CODE>yyIN_HEADER</CODE> is defined, where <SAMP>`yy'</SAMP> +is substituted with the appropriate prefix. + +The <SAMP>`--header-file'</SAMP> option is not compatible with the <SAMP>`--c++'</SAMP> option, since the C++ scanner provides its own header in <TT>`yyFlexLexer.h'</TT>. -<DT><SAMP>`-i, --case-insensitive'</SAMP> +@anchor{option-outfile} +<A NAME="IDX230"></A> +<A NAME="IDX231"></A> +<A NAME="IDX232"></A> +<DT><SAMP>`-oFILE, --outfile=FILE, <CODE>%option outfile="FILE"</CODE>'</SAMP> <DD> -instructs <CODE>flex</CODE> to generate a <EM>case-insensitive</EM> scanner. The -case of letters given in the <CODE>flex</CODE> input patterns will be ignored, -and tokens in the input will be matched regardless of case. The matched -text given in <CODE>yytext</CODE> will have the preserved case (i.e., it will -not be folded). +directs flex to write the scanner to the file <TT>`FILE'</TT> instead of +<TT>`lex.yy.c'</TT>. If you combine <SAMP>`--outfile'</SAMP> with the <SAMP>`--stdout'</SAMP> option, +then the scanner is written to <TT>`stdout'</TT> but its <CODE>#line</CODE> +directives (see the <SAMP>`-l'</SAMP> option above) refer to the file +<TT>`FILE'</TT>. -<DT><SAMP>`-l, --lex-compat'</SAMP> +@anchor{option-stdout} +<A NAME="IDX233"></A> +<A NAME="IDX234"></A> +<A NAME="IDX235"></A> +<DT><SAMP>`-t, --stdout, <CODE>%option stdout</CODE>'</SAMP> <DD> -turns on maximum compatibility with the original AT&T <CODE>lex</CODE> -implementation. Note that this does not mean <EM>full</EM> compatibility. -Use of this option costs a considerable amount of performance, and it -cannot be used with the <SAMP>`--c++'</SAMP>, <SAMP>`--full'</SAMP>, <SAMP>`--fast'</SAMP>, <SAMP>`-Cf'</SAMP>, or -<SAMP>`-CF'</SAMP> options. For details on the compatibilities it provides, see -section <A HREF="flex.html#SEC36">Incompatibilities with Lex and Posix</A>. This option also results in the name -<CODE>YY_FLEX_LEX_COMPAT</CODE> being <CODE>#define</CODE>'d in the generated scanner. +instructs <CODE>flex</CODE> to write the scanner it generates to standard +output instead of <TT>`lex.yy.c'</TT>. -<DT><SAMP>`-n'</SAMP> +<A NAME="IDX236"></A> +<DT><SAMP>`-SFILE, --skel=FILE'</SAMP> <DD> -is another do-nothing option included only for -POSIX compliance. +overrides the default skeleton file from which +<CODE>flex</CODE> +constructs its scanners. You'll never need this option unless you are doing +<CODE>flex</CODE> +maintenance or development. -<DT><SAMP>`-p, --perf-report'</SAMP> +<A NAME="IDX237"></A> +<A NAME="IDX238"></A> +<DT><SAMP>`--tables-file=FILE'</SAMP> <DD> -generates a performance report to <TT>`stderr'</TT>. The report consists of -comments regarding features of the <CODE>flex</CODE> 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 <CODE>REJECT</CODE>, <CODE>%option yylineno</CODE>, and -variable trailing context (see section <A HREF="flex.html#SEC38">Limitations</A>) entails a substantial -performance penalty; use of <CODE>yymore()</CODE>, the <SAMP>`^'</SAMP> operator, and -the <SAMP>`--interactive'</SAMP> flag entail minor performance penalties. +Write serialized scanner dfa tables to FILE. The generated scanner will not +contain the tables, and requires them to be loaded at runtime. +@xref{serialization}. -<DT><SAMP>`-s, --nodefault'</SAMP> +<A NAME="IDX239"></A> +<A NAME="IDX240"></A> +<DT><SAMP>`--tables-verify'</SAMP> <DD> -causes the <EM>default rule</EM> (that unmatched scanner input is echoed -to <TT>`stdout)'</TT> 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. +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 serialized tables match the in-code tables, instead of loading them. + +</DL> + -<DT><SAMP>`-t, --stdout'</SAMP> -<DD> -instructs <CODE>flex</CODE> to write the scanner it generates to standard -output instead of <TT>`lex.yy.c'</TT>. -<DT><SAMP>`-v, --verbose'</SAMP> +<H2><A NAME="SEC22" HREF="flex_toc.html#TOC22">Options Affecting Scanner Behavior</A></H2> + +<DL COMPACT> + +@anchor{option-case-insensitive} +<DT><SAMP>`-i, --case-insensitive, <CODE>%option case-insensitive</CODE>'</SAMP> <DD> -specifies that <CODE>flex</CODE> should write to <TT>`stderr'</TT> a summary of -statistics regarding the scanner it generates. Most of the statistics -are meaningless to the casual <CODE>flex</CODE> user, but the first line -identifies the version of <CODE>flex</CODE> (same as reported by <SAMP>`--version'</SAMP>), -and the next line the flags used when generating the scanner, including -those that are on by default. +<A NAME="IDX241"></A> + <A NAME="IDX242"></A> + <A NAME="IDX243"></A> + +instructs <CODE>flex</CODE> to generate a <EM>case-insensitive</EM> scanner. The +case of letters given in the <CODE>flex</CODE> input patterns will be ignored, +and tokens in the input will be matched regardless of case. The matched +text given in <CODE>yytext</CODE> will have the preserved case (i.e., it will +not be folded). -<DT><SAMP>`-w, --nowarn'</SAMP> +@anchor{option-lex-compat} +<A NAME="IDX244"></A> +<A NAME="IDX245"></A> +<A NAME="IDX246"></A> +<DT><SAMP>`-l, --lex-compat, <CODE>%option lex-compat</CODE>'</SAMP> <DD> -suppresses warning messages. +turns on maximum compatibility with the original AT&T <CODE>lex</CODE> +implementation. Note that this does not mean <EM>full</EM> compatibility. +Use of this option costs a considerable amount of performance, and it +cannot be used with the <SAMP>`--c++'</SAMP>, <SAMP>`--full'</SAMP>, <SAMP>`--fast'</SAMP>, <SAMP>`-Cf'</SAMP>, or +<SAMP>`-CF'</SAMP> options. For details on the compatibilities it provides, see +section <A HREF="flex.html#SEC42">Incompatibilities with Lex and Posix</A>. This option also results in the name +<CODE>YY_FLEX_LEX_COMPAT</CODE> being <CODE>#define</CODE>'d in the generated scanner. -<DT><SAMP>`-B, --batch'</SAMP> +@anchor{option-batch} +<A NAME="IDX247"></A> +<A NAME="IDX248"></A> +<A NAME="IDX249"></A> +<DT><SAMP>`-B, --batch, <CODE>%option batch</CODE>'</SAMP> <DD> instructs <CODE>flex</CODE> to generate a <EM>batch</EM> scanner, the opposite of <EM>interactive</EM> scanners generated by <SAMP>`--interactive'</SAMP> (see below). In @@ -2660,34 +2756,11 @@ <SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP> options, which turn on <SAMP>`--batch'</SAMP> automatically anyway. -<DT><SAMP>`-F, --fast'</SAMP> -<DD> -specifies that the <EM>fast</EM> scanner table representation should be -used (and <CODE>stdio</CODE> bypassed). This representation is about as fast -as the full table representation <SAMP>`--full'</SAMP>, and for some sets of -patterns will be considerably smaller (and for others, larger). In -general, if the pattern set contains both <EM>keywords</EM> and a -catch-all, <EM>identifier</EM> rule, such as in the set: - - -<PRE> -@verbatim - "case" return TOK_CASE; - "switch" return TOK_SWITCH; - ... - "default" return TOK_DEFAULT; - [a-z]+ return TOK_ID; -</PRE> - -then you're better off using the full table representation. If only -the <EM>identifier</EM> rule is present and you then use a hash table or some such -to detect the keywords, you're better off using -<SAMP>`--fast'</SAMP>. - -This option is equivalent to <SAMP>`-CFr'</SAMP> (see below). It cannot be used -with <SAMP>`--c++'</SAMP>. - -<DT><SAMP>`-I, --interactive'</SAMP> +@anchor{option-interactive} +<A NAME="IDX250"></A> +<A NAME="IDX251"></A> +<A NAME="IDX252"></A> +<DT><SAMP>`-I, --interactive, <CODE>%option interactive</CODE>'</SAMP> <DD> instructs <CODE>flex</CODE> to generate an <I>interactive</I> scanner. An interactive scanner is one that only looks ahead to decide what token @@ -2701,7 +2774,7 @@ <CODE>flex</CODE> scanners default to <CODE>interactive</CODE> unless you use the <SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP> table-compression options -(see section <A HREF="flex.html#SEC20">Performance Considerations</A>). That's because if you're looking for +(see section <A HREF="flex.html#SEC27">Performance Considerations</A>). That's because if you're looking for high-performance you should be using one of these options, so if you didn't, <CODE>flex</CODE> assumes you'd rather trade off a bit of run-time performance for intuitive interactive behavior. Note also that you @@ -2714,67 +2787,79 @@ be interactive by using <SAMP>`--batch'</SAMP> -<DT><SAMP>`-L, --noline'</SAMP> +@anchor{option-7bit} +<A NAME="IDX253"></A> +<A NAME="IDX254"></A> +<A NAME="IDX255"></A> +<DT><SAMP>`-7, --7bit, <CODE>%option 7bit</CODE>'</SAMP> <DD> -instructs -<CODE>flex</CODE> -not to generate -<CODE>#line</CODE> -directives. Without this option, -<CODE>flex</CODE> -peppers the generated scanner -with <CODE>#line</CODE> directives so error messages in the actions will be correctly -located with respect to either the original -<CODE>flex</CODE> -input file (if the errors are due to code in the input file), or -<TT>`lex.yy.c'</TT> -(if the errors are -<CODE>flex</CODE>'s -fault -- you should report these sorts of errors to the email address -given in section <A HREF="flex.html#SEC41">Reporting Bugs</A>). +instructs <CODE>flex</CODE> to generate a 7-bit scanner, i.e., one which can +only recognize 7-bit characters in its input. The advantage of using +<SAMP>`--7bit'</SAMP> is that the scanner's tables can be up to half the size of +those generated using the <SAMP>`--8bit'</SAMP>. The disadvantage is that such +scanners often hang or crash if their input contains an 8-bit character. -<DT><SAMP>`-R, --reentrant'</SAMP> -<DD> -instructs flex to generate a reentrant C scanner. The generated scanner -may safely be used in a multi-threaded environment. The API for a -reentrant scanner is different than for a non-reentrant scanner -see section <A HREF="flex.html#SEC22">Reentrant C Scanners</A>). Because of the API difference between -reentrant and non-reentrant <CODE>flex</CODE> scanners, non-reentrant flex -code must be modified before it is suitable for use with this option. -This option is not compatible with the <SAMP>`--c++'</SAMP> option. +Note, however, that unless you generate your scanner using the +<SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP> table compression options, use of <SAMP>`--7bit'</SAMP> +will save only a small amount of table space, and make your scanner +considerably less portable. <CODE>Flex</CODE>'s default behavior is to +generate an 8-bit scanner unless you use the <SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP>, +in which case <CODE>flex</CODE> 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 <SAMP>`--verbose'</SAMP> output as described above. -<DT><SAMP>`-Rb, --reentrant-bison'</SAMP> +Note that if you use <SAMP>`-Cfe'</SAMP> or <SAMP>`-CFe'</SAMP> <CODE>flex</CODE> 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. + +@anchor{option-8bit} +<A NAME="IDX256"></A> +<A NAME="IDX257"></A> +<A NAME="IDX258"></A> +<DT><SAMP>`-8, --8bit, <CODE>%option 8bit</CODE>'</SAMP> <DD> -instructs flex to generate a reentrant C scanner that is -meant to be called by a -<CODE>GNU bison</CODE> -pure parser. The scanner is the same as the scanner generated by the -<SAMP>`--reentrant'</SAMP> -option, but with minor API changes for -<CODE>bison</CODE> -compatibility. In particular, the declaration of -<CODE>yylex</CODE> -is modified, and support for -<CODE>yylval</CODE> -and -<CODE>yylloc</CODE> -is incorporated. See section <A HREF="flex.html#SEC34">Reentrant C Scanners with Bison Pure Parsers</A>. +instructs <CODE>flex</CODE> to generate an 8-bit scanner, i.e., one which can +recognize 8-bit characters. This flag is only needed for scanners +generated using <SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP>, as otherwise flex defaults to +generating an 8-bit scanner anyway. -The options <SAMP>`--reentrant'</SAMP> and <SAMP>`--reentrant-bison'</SAMP> do not affect the performance of -the scanner. +See the discussion of +<SAMP>`--7bit'</SAMP> +above for <CODE>flex</CODE>'s default behavior and the tradeoffs between 7-bit +and 8-bit scanners. -<DT><SAMP>`-T, --trace'</SAMP> +@anchor{option-default} +<A NAME="IDX259"></A> +<A NAME="IDX260"></A> +<DT><SAMP>`--default, <CODE>%option default</CODE>'</SAMP> <DD> -makes <CODE>flex</CODE> run in <EM>trace</EM> mode. It will generate a lot of -messages to <TT>`stderr'</TT> concerning the form of the input and the -resultant non-deterministic and deterministic finite automata. This -option is mostly for use in maintaining <CODE>flex</CODE>. +generate the default rule. -<DT><SAMP>`-V, --version'</SAMP> +@anchor{option-always-interactive} +<A NAME="IDX261"></A> +<A NAME="IDX262"></A> +<DT><SAMP>`--always-interactive, <CODE>%option always-interactive</CODE>'</SAMP> <DD> -prints the version number to <TT>`stdout'</TT> and exits. +instructs flex to generate a scanner which always considers its input +<EM>interactive</EM>. Normally, on each new input file the scanner calls +<CODE>isatty()</CODE> 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. -<DT><SAMP>`-X, --posix'</SAMP> +<A NAME="IDX263"></A> +<DT><SAMP>`--never-interactive, <CODE>--never-interactive</CODE>'</SAMP> +<DD> +instructs flex to generate a scanner which never considers its input +interactive. This is the opposite of <CODE>always-interactive</CODE>. + +@anchor{option-posix} +<A NAME="IDX264"></A> +<A NAME="IDX265"></A> +<A NAME="IDX266"></A> +<DT><SAMP>`-X, --posix, <CODE>%option posix</CODE>'</SAMP> <DD> turns on maximum compatibility with the POSIX 1003.2-1992 definition of <CODE>lex</CODE>. Since <CODE>flex</CODE> was originally designed to implement the @@ -2798,54 +2883,260 @@ where concatenation has higher precedence than the repeat operator. </UL> -<DT><SAMP>`-7, --7bit'</SAMP> +@anchor{option-stack} +<A NAME="IDX267"></A> +<A NAME="IDX268"></A> +<DT><SAMP>`--stack, <CODE>%option stack</CODE>'</SAMP> <DD> -instructs <CODE>flex</CODE> to generate a 7-bit scanner, i.e., one which can -only recognize 7-bit characters in its input. The advantage of using -<SAMP>`--7bit'</SAMP> is that the scanner's tables can be up to half the size of -those generated using the <SAMP>`--8bit'</SAMP>. The disadvantage is that such -scanners often hang or crash if their input contains an 8-bit character. +enables the use of +start condition stacks (see section <A HREF="flex.html#SEC14">Start Conditions</A>). -Note, however, that unless you generate your scanner using the -<SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP> table compression options, use of <SAMP>`--7bit'</SAMP> -will save only a small amount of table space, and make your scanner -considerably less portable. <CODE>Flex</CODE>'s default behavior is to -generate an 8-bit scanner unless you use the <SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP>, -in which case <CODE>flex</CODE> 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 <SAMP>`--verbose'</SAMP> output as described above. +@anchor{option-stdinit} +<A NAME="IDX269"></A> +<A NAME="IDX270"></A> +<DT><SAMP>`--stdinit, <CODE>%option stdinit</CODE>'</SAMP> +<DD> +if set (i.e., <B>%option stdinit)</B> initializes <CODE>yyin</CODE> and +<CODE>yyout</CODE> to <TT>`stdin'</TT> and <TT>`stdout'</TT>, instead of the default of +<TT>`nil'</TT>. Some existing <CODE>lex</CODE> programs depend on this behavior, +even though it is not compliant with ANSI C, which does not require +<TT>`stdin'</TT> and <TT>`stdout'</TT> to be compile-time constant. In a +reentrant scanner, however, this is not a problem since initialization +is performed in <CODE>yylex_init</CODE> at runtime. -Note that if you use <SAMP>`-Cfe'</SAMP> or <SAMP>`-CFe'</SAMP> <CODE>flex</CODE> 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. +@anchor{option-yylineno} +<A NAME="IDX271"></A> +<A NAME="IDX272"></A> +<DT><SAMP>`--yylineno, <CODE>%option yylineno</CODE>'</SAMP> +<DD> +directs <CODE>flex</CODE> to generate a scanner +that maintains the number of the current line read from its input in the +global variable <CODE>yylineno</CODE>. This option is implied by <CODE>%option +lex-compat</CODE>. In a reentrant C scanner, the macro <CODE>yylineno</CODE> is +accessible regardless of the value of <CODE>%option yylineno</CODE>, however, its +value is not modified by <CODE>flex</CODE> unless <CODE>%option yylineno</CODE> is enabled. -<DT><SAMP>`-8, --8bit'</SAMP> +@anchor{option-yywrap} +<A NAME="IDX273"></A> +<A NAME="IDX274"></A> +<DT><SAMP>`--yywrap, <CODE>%option yywrap</CODE>'</SAMP> <DD> -instructs <CODE>flex</CODE> to generate an 8-bit scanner, i.e., one which can -recognize 8-bit characters. This flag is only needed for scanners -generated using <SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP>, as otherwise flex defaults to -generating an 8-bit scanner anyway. +if unset (i.e., <CODE>--noyywrap)</CODE>, makes the scanner not call +<CODE>yywrap()</CODE> upon an end-of-file, but simply assume that there are no +more files to scan (until the user points <TT>`yyin'</TT> at a new file and +calls <CODE>yylex()</CODE> again). -See the discussion of -<SAMP>`--7bit'</SAMP> -above for <CODE>flex</CODE>'s default behavior and the tradeoffs between 7-bit -and 8-bit scanners. +</DL> + + + +<H2><A NAME="SEC23" HREF="flex_toc.html#TOC23">Code-Level And API Options</A></H2> + +<DL COMPACT> -<DT><SAMP>`-+, --c++'</SAMP> +@anchor{option-bison-bridge} +<DT><SAMP>`--bison-bridge, <CODE>%option bison-bridge</CODE>'</SAMP> +<DD> +<A NAME="IDX275"></A> + <A NAME="IDX276"></A> + +instructs flex to generate a C scanner that is +meant to be called by a +<CODE>GNU bison</CODE> +parser. The scanner has minor API changes for +<CODE>bison</CODE> +compatibility. In particular, the declaration of +<CODE>yylex</CODE> +is modified, and support for +<CODE>yylval</CODE> +and +<CODE>yylloc</CODE> +is incorporated. See section <A HREF="flex.html#SEC156">C Scanners with Bison Parsers</A>. + +@anchor{option-noline} +<A NAME="IDX277"></A> +<A NAME="IDX278"></A> +<A NAME="IDX279"></A> +<DT><SAMP>`-L, --noline, <CODE>%option noline</CODE>'</SAMP> +<DD> +instructs +<CODE>flex</CODE> +not to generate +<CODE>#line</CODE> +directives. Without this option, +<CODE>flex</CODE> +peppers the generated scanner +with <CODE>#line</CODE> directives so error messages in the actions will be correctly +located with respect to either the original +<CODE>flex</CODE> +input file (if the errors are due to code in the input file), or +<TT>`lex.yy.c'</TT> +(if the errors are +<CODE>flex</CODE>'s +fault -- you should report these sorts of errors to the email address +given in section <A HREF="flex.html#SEC2">Reporting Bugs</A>). + +@anchor{option-reentrant} +<A NAME="IDX280"></A> +<A NAME="IDX281"></A> +<A NAME="IDX282"></A> +<DT><SAMP>`-R, --reentrant, <CODE>%option reentrant</CODE>'</SAMP> +<DD> +instructs flex to generate a reentrant C scanner. The generated scanner +may safely be used in a multi-threaded environment. The API for a +reentrant scanner is different than for a non-reentrant scanner +see section <A HREF="flex.html#SEC29">Reentrant C Scanners</A>). Because of the API difference between +reentrant and non-reentrant <CODE>flex</CODE> scanners, non-reentrant flex +code must be modified before it is suitable for use with this option. +This option is not compatible with the <SAMP>`--c++'</SAMP> option. + +The option <SAMP>`--reentrant'</SAMP> does not affect the performance of +the scanner. + +@anchor{option-c++} +<A NAME="IDX283"></A> +<A NAME="IDX284"></A> +<A NAME="IDX285"></A> +<DT><SAMP>`-+, --c++, <CODE>%option c++</CODE>'</SAMP> <DD> specifies that you want flex to generate a C++ -scanner class. See section <A HREF="flex.html#SEC21">Generating C++ Scanners</A>, for +scanner class. See section <A HREF="flex.html#SEC28">Generating C++ Scanners</A>, for details. +@anchor{option-array} +<A NAME="IDX286"></A> +<A NAME="IDX287"></A> +<DT><SAMP>`--array, <CODE>%option array</CODE>'</SAMP> +<DD> +specifies that you want yytext to be an array instead of a char* + +@anchor{option-pointer} +<A NAME="IDX288"></A> +<A NAME="IDX289"></A> +<DT><SAMP>`--pointer, <CODE>%option pointer</CODE>'</SAMP> +<DD> +specify that <CODE>yytext</CODE> should be a <CODE>char *</CODE>, not an array. +This default is <CODE>char *</CODE>. + +@anchor{option-prefix} +<A NAME="IDX290"></A> +<A NAME="IDX291"></A> +<A NAME="IDX292"></A> +<DT><SAMP>`-PPREFIX, --prefix=PREFIX, <CODE>%option prefix="PREFIX"</CODE>'</SAMP> +<DD> +changes the default <SAMP>`yy'</SAMP> prefix used by <CODE>flex</CODE> for all +globally-visible variable and function names to instead be +<SAMP>`PREFIX'</SAMP>. For example, <SAMP>`--prefix=foo'</SAMP> changes the name of +<CODE>yytext</CODE> to <CODE>footext</CODE>. It also changes the name of the default +output file from <TT>`lex.yy.c'</TT> to <TT>`lex.foo.c'</TT>. Here is a partial +list of the names affected: + + +<PRE> +@verbatim + yy_create_buffer + yy_delete_buffer + yy_flex_debug + yy_init_buffer + yy_flush_buffer + yy_load_buffer_state + yy_switch_to_buffer + yyin + yyleng + yylex + yylineno + yyout + yyrestart + yytext + yywrap + yyalloc + yyrealloc + yyfree +</PRE> + +(If you are using a C++ scanner, then only <CODE>yywrap</CODE> and +<CODE>yyFlexLexer</CODE> 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 +<CODE>flex</CODE> +programs into the same executable. Note, though, that using this +option also renames +<CODE>yywrap()</CODE>, +so you now +<EM>must</EM> +either +provide your own (appropriately-named) version of the routine for your +scanner, or use +<CODE>%option noyywrap</CODE>, +as linking with +<SAMP>`-lfl'</SAMP> +no longer provides one for you by default. + +@anchor{option-main} +<A NAME="IDX293"></A> +<A NAME="IDX294"></A> +<DT><SAMP>`--main, <CODE>%option main</CODE>'</SAMP> +<DD> + directs flex to provide a default <CODE>main()</CODE> program for the +scanner, which simply calls <CODE>yylex()</CODE>. This option implies +<CODE>noyywrap</CODE> (see below). + +@anchor{option-nounistd} +<A NAME="IDX295"></A> +<A NAME="IDX296"></A> +<DT><SAMP>`--nounistd, <CODE>%option nounistd</CODE>'</SAMP> +<DD> +suppresses inclusion of the non-ANSI header file <TT>`unistd.h'</TT>. This option +is meant to target environments in which <TT>`unistd.h'</TT> does not exist. Be aware +that certain options may cause flex to generate code that relies on functions +normally found in <TT>`unistd.h'</TT>, (e.g. <CODE>isatty()</CODE>, <CODE>read()</CODE>.) +If you wish to use these functions, you will have to inform your compiler where +to find them. +@xref{option-always-interactive}. @xref{option-read}. + +@anchor{option-yyclass} +<A NAME="IDX297"></A> +<A NAME="IDX298"></A> +<DT><SAMP>`--yyclass, <CODE>%option yyclass="NAME"</CODE>'</SAMP> +<DD> +only applies when generating a C++ scanner (the <SAMP>`--c++'</SAMP> option). It +informs <CODE>flex</CODE> that you have derived <CODE>foo</CODE> as a subclass of +<CODE>yyFlexLexer</CODE>, so <CODE>flex</CODE> will place your actions in the member +function <CODE>foo::yylex()</CODE> instead of <CODE>yyFlexLexer::yylex()</CODE>. It +also generates a <CODE>yyFlexLexer::yylex()</CODE> member function that emits +a run-time error (by invoking <CODE>yyFlexLexer::LexerError())</CODE> if +called. See section <A HREF="flex.html#SEC28">Generating C++ Scanners</A>. + +</DL> + + + +<H2><A NAME="SEC24" HREF="flex_toc.html#TOC24">Options for Scanner Speed and Size</A></H2> + +<DL COMPACT> + <DT><SAMP>`-C[aefFmr]'</SAMP> <DD> controls the degree of table compression and, more generally, trade-offs between small scanners and fast scanners. -<DT><SAMP>`-Ca, --align'</SAMP> +<DL COMPACT> + +<DT><SAMP>`-C'</SAMP> +<DD> +<A NAME="IDX299"></A> + +A lone <SAMP>`-C'</SAMP> specifies that the scanner tables should be compressed +but neither equivalence classes nor meta-equivalence classes should be +used. + +@anchor{option-align} +<A NAME="IDX300"></A> +<A NAME="IDX301"></A> +<A NAME="IDX302"></A> +<DT><SAMP>`-Ca, --align, <CODE>%option align</CODE>'</SAMP> <DD> ("align") instructs flex to trade off larger tables in the generated scanner for faster performance because the elements of @@ -2854,7 +3145,11 @@ than with smaller-sized units such as shortwords. This option can quadruple the size of the tables used by your scanner. -<DT><SAMP>`-Ce, --ecs'</SAMP> +@anchor{option-ecs} +<A NAME="IDX303"></A> +<A NAME="IDX304"></A> +<A NAME="IDX305"></A> +<DT><SAMP>`-Ce, --ecs, <CODE>%option ecs</CODE>'</SAMP> <DD> directs <CODE>flex</CODE> to construct <EM>equivalence classes</EM>, i.e., sets of characters which have identical lexical properties (for example, if @@ -2865,19 +3160,25 @@ factor of 2-5) and are pretty cheap performance-wise (one array look-up per character scanned). +<A NAME="IDX306"></A> <DT><SAMP>`-Cf'</SAMP> <DD> specifies that the <EM>full</EM> scanner tables should be generated - <CODE>flex</CODE> should not compress the tables by taking advantages of similar transition functions for different states. +<A NAME="IDX307"></A> <DT><SAMP>`-CF'</SAMP> <DD> specifies that the alternate fast scanner representation (described above under the <SAMP>`--fast'</SAMP> flag) should be used. This option cannot be used with <SAMP>`--c++'</SAMP>. -<DT><SAMP>`-Cm, --meta-ecs'</SAMP> +@anchor{option-meta-ecs} +<A NAME="IDX308"></A> +<A NAME="IDX309"></A> +<A NAME="IDX310"></A> +<DT><SAMP>`-Cm, --meta-ecs, <CODE>%option meta-ecs</CODE>'</SAMP> <DD> directs <CODE>flex</CODE> @@ -2889,8 +3190,11 @@ have a moderate performance impact (one or two <CODE>if</CODE> tests and one array look-up per character scanned). -@anchor{Option-Read} -<DT><SAMP>`-Cr, --read'</SAMP> +@anchor{option-read} +<A NAME="IDX311"></A> +<A NAME="IDX312"></A> +<A NAME="IDX313"></A> +<DT><SAMP>`-Cr, --read, <CODE>%option read</CODE>'</SAMP> <DD> causes the generated scanner to <EM>bypass</EM> use of the standard I/O library (<CODE>stdio</CODE>) for input. Instead of calling <CODE>fread()</CODE> or @@ -2901,13 +3205,8 @@ example, you read from <TT>`yyin'</TT> using <CODE>stdio</CODE> prior to calling the scanner (because the scanner will miss whatever text your previous reads left in the <CODE>stdio</CODE> input buffer). <SAMP>`-Cr'</SAMP> has no effect -if you define <CODE>YY_INPUT()</CODE> (see section <A HREF="flex.html#SEC11">The Generated Scanner</A>). - -<DT><SAMP>`-C'</SAMP> -<DD> -A lone <SAMP>`-C'</SAMP> specifies that the scanner tables should be compressed -but neither equivalence classes nor meta-equivalence classes should be -used. +if you define <CODE>YY_INPUT()</CODE> (see section <A HREF="flex.html#SEC13">The Generated Scanner</A>). +</DL> The options <SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP> and <SAMP>`-Cm'</SAMP> do not make sense together - there is no opportunity for meta-equivalence classes if the @@ -2941,245 +3240,207 @@ <SAMP>`-Cfe'</SAMP> is often a good compromise between speed and size for production scanners. -<DT><SAMP>`-oFILE, --outfile=FILE'</SAMP> +@anchor{option-full} +<A NAME="IDX314"></A> +<A NAME="IDX315"></A> +<A NAME="IDX316"></A> +<DT><SAMP>`-f, --full, <CODE>%option full</CODE>'</SAMP> <DD> -directs flex to write the scanner to the file <TT>`FILE'</TT> instead of -<TT>`lex.yy.c'</TT>. If you combine <SAMP>`--outfile'</SAMP> with the <SAMP>`--stdout'</SAMP> option, -then the scanner is written to <TT>`stdout'</TT> but its <CODE>#line</CODE> -directives (see the <SAMP>`-l'</SAMP> option above) refer to the file -<TT>`FILE'</TT>. +specifies +<EM>fast scanner</EM>. +No table compression is done and <CODE>stdio</CODE> is bypassed. +The result is large but fast. This option is equivalent to +<SAMP>`--Cfr'</SAMP> -<DT><SAMP>`-PPREFIX, --prefix=PREFIX'</SAMP> +@anchor{option-fast} +<A NAME="IDX317"></A> +<A NAME="IDX318"></A> +<A NAME="IDX319"></A> +<DT><SAMP>`-F, --fast, <CODE>%option fast</CODE>'</SAMP> <DD> -changes the default <SAMP>`yy'</SAMP> prefix used by <CODE>flex</CODE> for all -globally-visible variable and function names to instead be -<SAMP>`PREFIX'</SAMP>. For example, <SAMP>`--prefix=foo'</SAMP> changes the name of -<CODE>yytext</CODE> to <CODE>footext</CODE>. It also changes the name of the default -output file from <TT>`lex.yy.c'</TT> to <TT>`lex.foo.c'</TT>. Here are all of -the names affected: +specifies that the <EM>fast</EM> scanner table representation should be +used (and <CODE>stdio</CODE> bypassed). This representation is about as fast +as the full table representation <SAMP>`--full'</SAMP>, and for some sets of +patterns will be considerably smaller (and for others, larger). In +general, if the pattern set contains both <EM>keywords</EM> and a +catch-all, <EM>identifier</EM> rule, such as in the set: <PRE> @verbatim - yy_create_buffer - yy_delete_buffer - yy_flex_debug - yy_init_buffer - yy_flush_buffer - yy_load_buffer_state - yy_switch_to_buffer - yyin - yyleng - yylex - yylineno - yyout - yyrestart - yytext - yywrap + "case" return TOK_CASE; + "switch" return TOK_SWITCH; + ... + "default" return TOK_DEFAULT; + [a-z]+ return TOK_ID; </PRE> -(If you are using a C++ scanner, then only <CODE>yywrap</CODE> and -<CODE>yyFlexLexer</CODE> 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 -<CODE>flex</CODE> -programs into the same executable. Note, though, that using this -option also renames -<CODE>yywrap()</CODE>, -so you now -<EM>must</EM> -either -provide your own (appropriately-named) version of the routine for your -scanner, or use -<CODE>%option noyywrap</CODE>, -as linking with -<SAMP>`-lfl'</SAMP> -no longer provides one for you by default. - -<DT><SAMP>`-SFILE, --skel=FILE'</SAMP> -<DD> -overrides the default skeleton file from which -<CODE>flex</CODE> -constructs its scanners. You'll never need this option unless you are doing -<CODE>flex</CODE> -maintenance or development. +then you're better off using the full table representation. If only +the <EM>identifier</EM> rule is present and you then use a hash table or some such +to detect the keywords, you're better off using +<SAMP>`--fast'</SAMP>. -@anchor{Option-Always-Interactive} -<DT><SAMP>`--always-interactive'</SAMP> -<DD> -instructs flex to generate a scanner which always considers its input -<EM>interactive</EM>. Normally, on each new input file the scanner calls -<CODE>isatty()</CODE> 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. +This option is equivalent to <SAMP>`-CFr'</SAMP> (see below). It cannot be used +with <SAMP>`--c++'</SAMP>. -<DT><SAMP>`--main'</SAMP> -<DD> - directs flex to provide a default <CODE>main()</CODE> program for the -scanner, which simply calls <CODE>yylex()</CODE>. This option implies -<CODE>noyywrap</CODE> (see below). +</DL> -<DT><SAMP>`--never-interactive'</SAMP> -<DD> -instructs flex to generate a scanner which never considers its input -interactive. This is the opposite of <CODE>always-interactive</CODE>. -<DT><SAMP>`--nounistd'</SAMP> -<DD> -suppresses inclusion of the non-ANSI header file <TT>`unistd.h'</TT>. This option -is meant to target environments in which <TT>`unistd.h'</TT> does not exist. Be aware -that certain options may cause flex to generate code that relies on functions -normally found in <TT>`unistd.h'</TT>, (e.g. <CODE>isatty()</CODE>, <CODE>read()</CODE>.) -If you wish to use these functions, you will have to inform your compiler where -to find them. -@xref{Option-Always-Interactive}. @xref{Option-Read}. -<DT><SAMP>`--stack'</SAMP> -<DD> -enables the use of -start condition stacks (see section <A HREF="flex.html#SEC12">Start Conditions</A>). +<H2><A NAME="SEC25" HREF="flex_toc.html#TOC25">Debugging Options</A></H2> -<DT><SAMP>`--stdinit'</SAMP> -<DD> -if set (i.e., <B>%option stdinit)</B> initializes <CODE>yyin</CODE> and -<CODE>yyout</CODE> to <TT>`stdin'</TT> and <TT>`stdout'</TT>, instead of the default of -<TT>`nil'</TT>. Some existing <CODE>lex</CODE> programs depend on this behavior, -even though it is not compliant with ANSI C, which does not require -<TT>`stdin'</TT> and <TT>`stdout'</TT> to be compile-time constant. In a -reentrant scanner, however, this is not a problem since initialization -is performed in <CODE>yylex_init</CODE> at runtime. +<DL COMPACT> -<DT><SAMP>`--yylineno'</SAMP> +@anchor{option-backup} +<DT><SAMP>`-b, --backup, <CODE>%option backup</CODE>'</SAMP> <DD> -directs <CODE>flex</CODE> to generate a scanner -that maintains the number of the current line read from its input in the -global variable <CODE>yylineno</CODE>. This option is implied by <CODE>%option -lex-compat</CODE>. In a reentrant C scanner, the macro <CODE>yylineno</CODE> is -accessible regardless of the value of <CODE>%option yylineno</CODE>, however, its -value is not modified by <CODE>flex</CODE> unless <CODE>%option yylineno</CODE> is enabled. +<A NAME="IDX320"></A> + <A NAME="IDX321"></A> + <A NAME="IDX322"></A> + +Generate backing-up information to <TT>`lex.backup'</TT>. 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 +<EM>all</EM> backing-up states are eliminated and <SAMP>`-Cf'</SAMP> or <CODE>-CF</CODE> +is used, the generated scanner will run faster (see the <SAMP>`--perf-report'</SAMP> flag). +Only users who wish to squeeze every last cycle out of their scanners +need worry about this option. (see section <A HREF="flex.html#SEC27">Performance Considerations</A>). -<DT><SAMP>`--yywrap'</SAMP> +@anchor{option-debug} +<A NAME="IDX323"></A> +<A NAME="IDX324"></A> +<A NAME="IDX325"></A> +<DT><SAMP>`-d, --debug, <CODE>%option debug</CODE>'</SAMP> <DD> -if unset (i.e., <CODE>--noyywrap)</CODE>, makes the scanner not call -<CODE>yywrap()</CODE> upon an end-of-file, but simply assume that there are no -more files to scan (until the user points <TT>`yyin'</TT> at a new file and -calls <CODE>yylex()</CODE> again). -</DL> - +makes the generated scanner run in <EM>debug</EM> mode. Whenever a pattern +is recognized and the global variable <CODE>yy_flex_debug</CODE> is non-zero +(which is the default), the scanner will write to <TT>`stderr'</TT> a line +of the form: -<H1><A NAME="SEC19" HREF="flex_toc.html#TOC19">Option Directives Within Scanners</A></H1> +<PRE> +@verbatim + -accepting rule at line 53 ("the matched text") +</PRE> -<P> -<CODE>flex</CODE> also provides a mechanism for controlling options within the -scanner specification itself, rather than from the flex command-line. -This is done by including <CODE>%option</CODE> directives in the first section -of the scanner specification. You can specify multiple options with a -single <CODE>%option</CODE> directive, and multiple directives in the first -section of your flex input file. +The line number refers to the location of the rule in the file defining +the scanner (i.e., the file that was fed to flex). Messages are also +generated when the scanner backs up, accepts the default rule, reaches +the end of its input buffer (or encounters a NUL; at this point, the two +look the same as far as the scanner's concerned), or reaches an +end-of-file. +@anchor{option-perf-report} +<A NAME="IDX326"></A> +<A NAME="IDX327"></A> +<A NAME="IDX328"></A> +<DT><SAMP>`-p, --perf-report, <CODE>%option perf-report</CODE>'</SAMP> +<DD> +generates a performance report to <TT>`stderr'</TT>. The report consists of +comments regarding features of the <CODE>flex</CODE> 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. -<P> -Most options are given simply as names, optionally preceded by the -word <SAMP>`no'</SAMP> (with no intervening whitespace) to negate their meaning. -The names are the same as their long-option equivalents (but without the -leading <SAMP>`--'</SAMP> ). +Note that the use of <CODE>REJECT</CODE>, and +variable trailing context (see section <A HREF="flex.html#SEC52">Limitations</A>) entails a substantial +performance penalty; use of <CODE>yymore()</CODE>, the <SAMP>`^'</SAMP> operator, and +the <SAMP>`--interactive'</SAMP> flag entail minor performance penalties. +@anchor{option-nodefault} +<A NAME="IDX329"></A> +<A NAME="IDX330"></A> +<A NAME="IDX331"></A> +<DT><SAMP>`-s, --nodefault, <CODE>%option nodefault</CODE>'</SAMP> +<DD> +causes the <EM>default rule</EM> (that unmatched scanner input is echoed +to <TT>`stdout)'</TT> 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. +@anchor{option-trace} +<A NAME="IDX332"></A> +<A NAME="IDX333"></A> +<A NAME="IDX334"></A> +<DT><SAMP>`-T, --trace, <CODE>%option trace</CODE>'</SAMP> +<DD> +makes <CODE>flex</CODE> run in <EM>trace</EM> mode. It will generate a lot of +messages to <TT>`stderr'</TT> concerning the form of the input and the +resultant non-deterministic and deterministic finite automata. This +option is mostly for use in maintaining <CODE>flex</CODE>. -<PRE> -@verbatim - 7bit -7 --7bit - 8bit -8 --8bit - align -Ca --align - array --array equivalent to "%array" - backup -b --backup - batch -B --batch - c++ -+ --c++ - - caseful or - case-sensitive (default) - - case-insensitive or - caseless -i --case-insensitive - - debug -d --debug - default --default - ecs -Ce --ecs - fast -F --fast - full -f --full - header="FILE" --header=FILE - interactive -I --interactive - lex-compat -l --lex-compat - meta-ecs -Cm --meta-ecs - nounistd --nounistd - perf-report -p --perf-report - pointer --pointer equivalent to "%pointer" (default) - prefix="PREFIX" -P --prefix - outfile="FILE" -o --outfile=FILE - read -Cr --read - reentrant -R --reentrant - reentrant-bison -Rb --reentrant-bison - stdout -t --stdout - verbose -v --verbose - warn --warn (use "%option nowarn" for -w) - yyclass="NAME" --yyclass=NAME +@anchor{option-nowarn} +<A NAME="IDX335"></A> +<A NAME="IDX336"></A> +<A NAME="IDX337"></A> +<DT><SAMP>`-w, --nowarn, <CODE>%option nowarn</CODE>'</SAMP> +<DD> +suppresses warning messages. -</PRE> +@anchor{option-verbose} +<A NAME="IDX338"></A> +<A NAME="IDX339"></A> +<A NAME="IDX340"></A> +<DT><SAMP>`-v, --verbose, <CODE>%option verbose</CODE>'</SAMP> +<DD> +specifies that <CODE>flex</CODE> should write to <TT>`stderr'</TT> a summary of +statistics regarding the scanner it generates. Most of the statistics +are meaningless to the casual <CODE>flex</CODE> user, but the first line +identifies the version of <CODE>flex</CODE> (same as reported by <SAMP>`--version'</SAMP>), +and the next line the flags used when generating the scanner, including +those that are on by default. -<P> -<CODE>flex</CODE> scans your rule actions to determine whether you use the -<CODE>REJECT</CODE> or <CODE>yymore()</CODE> features. The <CODE>REJECT</CODE> and -<CODE>yymore</CODE> options are available to override its decision as to -whether you use the options, either by setting them (e.g., <CODE>%option -reject)</CODE> to indicate the feature is indeed used, or unsetting them to -indicate it actually is not used (e.g., <CODE>%option noyymore)</CODE>. +@anchor{option-warn} +<A NAME="IDX341"></A> +<A NAME="IDX342"></A> +<DT><SAMP>`--warn, <CODE>%option warn</CODE>'</SAMP> +<DD> +warn about certain things. In particular, if the default rule can be +matched but no defualt rule has been given, the flex will warn you. +We recommend using this option always. +</DL> -<P> -<CODE>%option yyclass</CODE> -only applies when generating a C++ scanner (the <SAMP>`--c++'</SAMP> option). It -informs <CODE>flex</CODE> that you have derived <CODE>foo</CODE> as a subclass of -<CODE>yyFlexLexer</CODE>, so <CODE>flex</CODE> will place your actions in the member -function <CODE>foo::yylex()</CODE> instead of <CODE>yyFlexLexer::yylex()</CODE>. It -also generates a <CODE>yyFlexLexer::yylex()</CODE> member function that emits -a run-time error (by invoking <CODE>yyFlexLexer::LexerError())</CODE> if -called. See section <A HREF="flex.html#SEC21">Generating C++ Scanners</A>. -<P> -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., <CODE>%option nounput</CODE>), results in the -corresponding routine not appearing in the generated scanner: +<H2><A NAME="SEC26" HREF="flex_toc.html#TOC26">Miscellaneous Options</A></H2> +<DL COMPACT> +<DT><SAMP>`-c'</SAMP> +<DD> +<A NAME="IDX343"></A> + +is a do-nothing option included for POSIX compliance. -<PRE> -@verbatim - input, unput - yy_push_state, yy_pop_state, yy_top_state - yy_scan_buffer, yy_scan_bytes, yy_scan_string +<A NAME="IDX344"></A> +<A NAME="IDX345"></A> +generates +<DT><SAMP>`-h, -?, --help'</SAMP> +<DD> +generates a "help" summary of <CODE>flex</CODE>'s options to <TT>`stdout'</TT> +and then exits. - yyget_extra, yyset_extra, yyget_leng, yyget_text, - yyget_lineno, yyset_lineno, yyget_in, yyset_in, - yyget_out, yyset_out, yyget_lval, yyset_lval, - yyget_lloc, yyset_lloc, -</PRE> +<A NAME="IDX346"></A> +<DT><SAMP>`-n'</SAMP> +<DD> +is another do-nothing option included only for +POSIX compliance. -<P> -(though <CODE>yy_push_state()</CODE> and friends won't appear anyway unless -you use <CODE>%option stack)</CODE>. +<A NAME="IDX347"></A> +<A NAME="IDX348"></A> +<DT><SAMP>`-V, --version'</SAMP> +<DD> +prints the version number to <TT>`stdout'</TT> and exits. +</DL> -<H1><A NAME="SEC20" HREF="flex_toc.html#TOC20">Performance Considerations</A></H1> +<H1><A NAME="SEC27" HREF="flex_toc.html#TOC27">Performance Considerations</A></H1> <P> -<A NAME="IDX202"></A> +<A NAME="IDX349"></A> The main design goal of <CODE>flex</CODE> 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 @@ -3188,18 +3449,19 @@ <P> -<A NAME="IDX203"></A> -<A NAME="IDX204"></A> -<A NAME="IDX205"></A> +<A NAME="IDX350"></A> +<A NAME="IDX351"></A> +<A NAME="IDX352"></A> <PRE> @verbatim REJECT - %option yylineno arbitrary trailing context pattern sets that require backing up + %option yylineno %array + %option interactive %option always-interactive @@ -3208,7 +3470,7 @@ </PRE> <P> -with the first three all being quite expensive and the last two being +with the first two all being quite expensive and the last two being quite cheap. Note also that <CODE>unput()</CODE> is implemented as a routine call that potentially does quite a bit of work, while <CODE>yyless()</CODE> is a quite-cheap macro. So if you are just putting back some excess text @@ -3221,9 +3483,32 @@ <P> -<A NAME="IDX206"></A> -<A NAME="IDX207"></A> -<A NAME="IDX208"></A> +There is one case when <CODE>%option yylineno</CODE> can be expensive. That is when +your patterns match long tokens that could <EM>possibly</EM> contain a 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 <CODE>[^f]+</CODE>, which match very long +tokens, including newlines, and may possibly match your entire file! A better +approach is to separate <CODE>[^f]+</CODE> into two rules: + + + +<PRE> +@verbatim +%option yylineno +%% + [^f\n]+ + \n+ +</PRE> + +<P> +The above scanner does not incur a performance penalty. + + +<P> +<A NAME="IDX353"></A> +<A NAME="IDX354"></A> +<A NAME="IDX355"></A> 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 <SAMP>`-b'</SAMP> flag to generate a <TT>`lex.backup'</TT> file. For example, @@ -3231,7 +3516,7 @@ <P> -<A NAME="IDX209"></A> +<A NAME="IDX356"></A> <PRE> @verbatim @@ -3297,12 +3582,12 @@ <P> -<A NAME="IDX210"></A> +<A NAME="IDX357"></A> The way to remove the backing up is to add "error" rules: <P> -<A NAME="IDX211"></A> +<A NAME="IDX358"></A> <PRE> @verbatim @@ -3324,7 +3609,7 @@ <P> -<A NAME="IDX212"></A> +<A NAME="IDX359"></A> <PRE> @verbatim @@ -3362,7 +3647,7 @@ <P> -<A NAME="IDX213"></A> +<A NAME="IDX360"></A> <PRE> @verbatim @@ -3396,7 +3681,7 @@ <P> Note that here the special '|' action does <EM>not</EM> provide any -savings, and can even make things worse (see section <A HREF="flex.html#SEC38">Limitations</A>). +savings, and can even make things worse (see section <A HREF="flex.html#SEC52">Limitations</A>). <P> @@ -3410,7 +3695,7 @@ <P> -<A NAME="IDX214"></A> +<A NAME="IDX361"></A> <PRE> @verbatim @@ -3457,8 +3742,8 @@ <P> -<A NAME="IDX215"></A> -<A NAME="IDX216"></A> +<A NAME="IDX362"></A> +<A NAME="IDX363"></A> A final example in speeding up a scanner: suppose you want to scan through a file containing identifiers and keywords, one per line and with no other extraneous characters, and recognize all the @@ -3466,7 +3751,7 @@ <P> -<A NAME="IDX217"></A> +<A NAME="IDX364"></A> <PRE> @verbatim @@ -3569,7 +3854,7 @@ <P> Another final note regarding performance: as mentioned in -section <A HREF="flex.html#SEC9">How the Input Is Matched</A>, dynamically resizing <CODE>yytext</CODE> to accommodate huge +section <A HREF="flex.html#SEC11">How the Input Is Matched</A>, dynamically resizing <CODE>yytext</CODE> 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 @@ -3579,16 +3864,23 @@ -<H1><A NAME="SEC21" HREF="flex_toc.html#TOC21">Generating C++ Scanners</A></H1> +<H1><A NAME="SEC28" HREF="flex_toc.html#TOC28">Generating C++ Scanners</A></H1> <P> -<A NAME="IDX218"></A> -<A NAME="IDX219"></A> -<A NAME="IDX220"></A> +<A NAME="IDX365"></A> +<A NAME="IDX366"></A> +<STRONG>IMPORTANT</STRONG>: the present form of the scanning class is <EM>experimental</EM> +and may change considerably between major releases. + + +<P> +<A NAME="IDX367"></A> +<A NAME="IDX368"></A> +<A NAME="IDX369"></A> <CODE>flex</CODE> provides two different ways to generate scanners for use with C++. The first way is to simply compile a scanner generated by <CODE>flex</CODE> using a C++ compiler instead of a C compiler. You should -not encounter any compilation errors (see section <A HREF="flex.html#SEC41">Reporting Bugs</A>). You can +not encounter any compilation errors (see section <A HREF="flex.html#SEC2">Reporting Bugs</A>). You can then use C++ code in your rule actions instead of C code. Note that the default input source for your scanner remains <TT>`yyin'</TT>, and default echoing is still done to <TT>`yyout'</TT>. Both of these remain <CODE>FILE @@ -3616,32 +3908,32 @@ <DT><CODE>const char* YYText()</CODE> <DD> -<A NAME="IDX221"></A> +<A NAME="IDX370"></A> returns the text of the most recently matched token, the equivalent of <CODE>yytext</CODE>. -<A NAME="IDX222"></A> +<A NAME="IDX371"></A> <DT><CODE>int YYLeng()</CODE> <DD> returns the length of the most recently matched token, the equivalent of <CODE>yyleng</CODE>. -<A NAME="IDX223"></A> +<A NAME="IDX372"></A> <DT><CODE>int lineno() const</CODE> <DD> returns the current input line number (see <CODE>%option yylineno)</CODE>, or <CODE>1</CODE> if <CODE>%option yylineno</CODE> was not used. -<A NAME="IDX224"></A> +<A NAME="IDX373"></A> <DT><CODE>void set_debug( int flag )</CODE> <DD> sets the debugging flag for the scanner, equivalent to assigning to -<CODE>yy_flex_debug</CODE> (see section <A HREF="flex.html#SEC18">Invoking Flex</A>). Note that you must build +<CODE>yy_flex_debug</CODE> (see section <A HREF="flex.html#SEC20">Scanner Options</A>). Note that you must build the scannerusing <CODE>%option debug</CODE> to include debugging information in it. -<A NAME="IDX225"></A> +<A NAME="IDX374"></A> <DT><CODE>int debug() const</CODE> <DD> returns the current setting of the debugging flag. @@ -3657,8 +3949,8 @@ <P> -<A NAME="IDX226"></A> -<A NAME="IDX227"></A> +<A NAME="IDX375"></A> +<A NAME="IDX376"></A> The second class defined in <TT>`FlexLexer.h'</TT> is <CODE>yyFlexLexer</CODE>, which is derived from <CODE>FlexLexer</CODE>. It defines the following additional member functions: @@ -3668,13 +3960,13 @@ <DT><CODE>yyFlexLexer( istream* arg_yyin = 0, ostream* arg_yyout = 0 )</CODE> <DD> -<A NAME="IDX228"></A> +<A NAME="IDX377"></A> constructs a <CODE>yyFlexLexer</CODE> object using the given streams for input and output. If not specified, the streams default to <CODE>cin</CODE> and <CODE>cout</CODE>, respectively. -<A NAME="IDX229"></A> +<A NAME="IDX378"></A> <DT><CODE>virtual int yylex()</CODE> <DD> performs the same role is <CODE>yylex()</CODE> does for ordinary <CODE>flex</CODE> @@ -3688,7 +3980,7 @@ (and also generates a dummy <CODE>yyFlexLexer::yylex()</CODE> that calls <CODE>yyFlexLexer::LexerError()</CODE> if called). -<A NAME="IDX230"></A> +<A NAME="IDX379"></A> <DT><CODE>virtual void switch_streams(istream* new_in = 0, ostream* new_out = 0)</CODE> <DD> reassigns <CODE>yyin</CODE> to <CODE>new_in</CODE> (if non-nil) and <CODE>yyout</CODE> to @@ -3711,26 +4003,26 @@ <DT><CODE>virtual int LexerInput( char* buf, int max_size )</CODE> <DD> -<A NAME="IDX231"></A> +<A NAME="IDX380"></A> reads up to <CODE>max_size</CODE> characters into <CODE>buf</CODE> and returns the number of characters read. To indicate end-of-input, return 0 characters. Note that <CODE>interactive</CODE> scanners (see the <SAMP>`-B'</SAMP> -and <SAMP>`-I'</SAMP> flags in section <A HREF="flex.html#SEC18">Invoking Flex</A>) define the macro +and <SAMP>`-I'</SAMP> flags in section <A HREF="flex.html#SEC20">Scanner Options</A>) define the macro <CODE>YY_INTERACTIVE</CODE>. If you redefine <CODE>LexerInput()</CODE> 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 <CODE>#ifdef</CODE> statements. -<A NAME="IDX232"></A> +<A NAME="IDX381"></A> <DT><CODE>virtual void LexerOutput( const char* buf, int size )</CODE> <DD> writes out <CODE>size</CODE> characters from the buffer <CODE>buf</CODE>, which, while <CODE>NUL</CODE>-terminated, may also contain internal <CODE>NUL</CODE>s if the scanner's rules can match text with <CODE>NUL</CODE>s in them. -<A NAME="IDX233"></A> -<A NAME="IDX234"></A> +<A NAME="IDX382"></A> +<A NAME="IDX383"></A> <DT><CODE>virtual void LexerError( const char* msg )</CODE> <DD> reports a fatal error message. The default version of this function @@ -3740,10 +4032,10 @@ <P> Note that a <CODE>yyFlexLexer</CODE> object contains its <EM>entire</EM> scanning state. Thus you can use such objects to create reentrant -scanners. You can instantiate multiple instances of the same -<CODE>yyFlexLexer</CODE> class, and you can also combine multiple C++ scanner -classes together in the same program using the <SAMP>`-P'</SAMP> option -discussed above. +scanners, but see also section <A HREF="flex.html#SEC29">Reentrant C Scanners</A>. You can instantiate multiple +instances of the same <CODE>yyFlexLexer</CODE> class, and you can also combine +multiple C++ scanner classes together in the same program using the +<SAMP>`-P'</SAMP> option discussed above. <P> @@ -3756,7 +4048,7 @@ <P> -<A NAME="IDX235"></A> +<A NAME="IDX384"></A> <PRE> @verbatim @@ -3819,7 +4111,7 @@ </PRE> <P> -<A NAME="IDX236"></A> +<A NAME="IDX385"></A> If you want to create multiple (different) lexer classes, you use the <SAMP>`-P'</SAMP> flag (or the <CODE>prefix=</CODE> option) to rename each <CODE>yyFlexLexer</CODE> to some other <SAMP>`xxFlexLexer'</SAMP>. You then can @@ -3828,9 +4120,9 @@ <P> -<A NAME="IDX237"></A> -<A NAME="IDX238"></A> -<A NAME="IDX239"></A> +<A NAME="IDX386"></A> +<A NAME="IDX387"></A> +<A NAME="IDX388"></A> <PRE> @verbatim @@ -3848,30 +4140,23 @@ scanners and <CODE>%option prefix="zz"</CODE> for the other. -<P> -IMPORTANT: the present form of the scanning class is <EM>experimental</EM> -and may change considerably between major releases. - - -<H1><A NAME="SEC22" HREF="flex_toc.html#TOC22">Reentrant C Scanners</A></H1> +<H1><A NAME="SEC29" HREF="flex_toc.html#TOC29">Reentrant C Scanners</A></H1> <P> -<A NAME="IDX240"></A> +<A NAME="IDX389"></A> <CODE>flex</CODE> has the ability to generate a reentrant C scanner. This is -accomplished by specifying <CODE>%option reentrant</CODE> (<SAMP>`-R'</SAMP>) or -<CODE>%option reentrant-bison</CODE> (<SAMP>`-Rb'</SAMP>). The generated scanner is -both portable, and safe to use in one or more separate threads of +accomplished by specifying <CODE>%option reentrant</CODE> (<SAMP>`-R'</SAMP>) 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 <CODE>flex</CODE> scanner without the need for synchronization with -other threads. +multi-threaded applications. Any thread may create and execute a reentrant +<CODE>flex</CODE> scanner without the need for synchronization with other threads. -<H2><A NAME="SEC23" HREF="flex_toc.html#TOC23">Uses for Reentrant Scanners</A></H2> +<H2><A NAME="SEC30" HREF="flex_toc.html#TOC30">Uses for Reentrant Scanners</A></H2> <P> However, there are other uses for a reentrant scanner. For example, you @@ -3880,7 +4165,7 @@ <P> -<A NAME="IDX241"></A> +<A NAME="IDX390"></A> <PRE> @verbatim @@ -3901,7 +4186,7 @@ <P> 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. See section <A HREF="flex.html#SEC13">Multiple Input Buffers</A>.) +buffer states. See section <A HREF="flex.html#SEC15">Multiple Input Buffers</A>.) <P> @@ -3910,7 +4195,7 @@ <P> -<A NAME="IDX242"></A> +<A NAME="IDX391"></A> <PRE> @verbatim @@ -3919,12 +4204,12 @@ %option reentrant %% - "eval(".+")" { + "eval(".+")" { yyscan_t scanner; YY_BUFFER_STATE buf; yylex_init( &scanner ); - yytext[yyleng-1] = ' '; + yytext[yyleng-1] = ' '; buf = yy_scan_string( yytext + 5, scanner ); yylex( scanner ); @@ -3938,10 +4223,10 @@ -<H2><A NAME="SEC24" HREF="flex_toc.html#TOC24">An Overview of the Reentrant API</A></H2> +<H2><A NAME="SEC31" HREF="flex_toc.html#TOC31">An Overview of the Reentrant API</A></H2> <P> -<A NAME="IDX243"></A> +<A NAME="IDX392"></A> The API for reentrant scanners is different than for non-reentrant scanners. Here is a quick overview of the API: @@ -3952,7 +4237,7 @@ <LI> -All functions take one additional argument: <CODE>yy_globals</CODE> +All functions take one additional argument: <CODE>yyscanner</CODE> <LI> @@ -3976,11 +4261,11 @@ -<H2><A NAME="SEC25" HREF="flex_toc.html#TOC25">Reentrant Example</A></H2> +<H2><A NAME="SEC32" HREF="flex_toc.html#TOC32">Reentrant Example</A></H2> <P> First, an example of a reentrant scanner: -<A NAME="IDX244"></A> +<A NAME="IDX393"></A> <PRE> @verbatim @@ -3988,15 +4273,15 @@ %option reentrant stack %x COMMENT %% - "//" yy_push_state( COMMENT, yy_globals); + "//" yy_push_state( COMMENT, yyscanner); .|\n - <COMMENT>\n yy_pop_state( yy_globals ); + <COMMENT>\n yy_pop_state( yyscanner ); <COMMENT>[^\n]+ fprintf( yyout, "%s\n", yytext); %% - int main ( int argc, char * argv[] ) + int main ( int argc, char * argv[] ) { yyscan_t scanner; - + yylex_init ( &scanner ); yylex ( scanner ); yylex_destroy ( scanner ); @@ -4006,7 +4291,7 @@ -<H2><A NAME="SEC26" HREF="flex_toc.html#TOC26">The Reentrant API in Detail</A></H2> +<H2><A NAME="SEC33" HREF="flex_toc.html#TOC33">The Reentrant API in Detail</A></H2> <P> Here are the things you need to do or know to use the reentrant C API of @@ -4015,7 +4300,7 @@ -<H3><A NAME="SEC27" HREF="flex_toc.html#TOC27">Declaring a Scanner As Reentrant</A></H3> +<H3><A NAME="SEC34" HREF="flex_toc.html#TOC34">Declaring a Scanner As Reentrant</A></H3> <P> %option reentrant (--reentrant) must be specified. @@ -4023,7 +4308,7 @@ <P> Notice that <CODE>%option reentrant</CODE> is specified in the above example -(see section <A HREF="flex.html#SEC25">Reentrant Example</A>. Had this option not been specified, +(see section <A HREF="flex.html#SEC32">Reentrant Example</A>. Had this option not been specified, <CODE>flex</CODE> would have happily generated a non-reentrant scanner without complaining. You may explicitly specify <CODE>%option noreentrant</CODE>, if you do <EM>not</EM> want a reentrant scanner, although it is not @@ -4032,17 +4317,17 @@ -<H3><A NAME="SEC28" HREF="flex_toc.html#TOC28">The Extra Argument</A></H3> +<H3><A NAME="SEC35" HREF="flex_toc.html#TOC35">The Extra Argument</A></H3> <P> -<A NAME="IDX245"></A> -<A NAME="IDX246"></A> -All functions take one additional argument: <CODE>yy_globals</CODE>. +<A NAME="IDX394"></A> +<A NAME="IDX395"></A> +All functions take one additional argument: <CODE>yyscanner</CODE>. <P> Notice that the calls to <CODE>yy_push_state</CODE> and <CODE>yy_pop_state</CODE> -both have an argument, <CODE>yy_globals</CODE> , that is not present in a +both have an argument, <CODE>yyscanner</CODE> , that is not present in a non-reentrant scanner. Here are the declarations of <CODE>yy_push_state</CODE> and <CODE>yy_pop_state</CODE> in the generated scanner: @@ -4050,30 +4335,30 @@ <PRE> @verbatim - static void yy_push_state ( int new_state , yyscan_t yy_globals ) ; - static void yy_pop_state ( yyscan_t yy_globals ) ; + static void yy_push_state ( int new_state , yyscan_t yyscanner ) ; + static void yy_pop_state ( yyscan_t yyscanner ) ; </PRE> <P> -Notice that the argument <CODE>yy_globals</CODE> appears in the declaration of +Notice that the argument <CODE>yyscanner</CODE> appears in the declaration of both functions. In fact, all <CODE>flex</CODE> functions in a reentrant scanner have this additional argument. It is always the last argument in the argument list, it is always of type <CODE>yyscan_t</CODE> (which is typedef'd to <CODE>void *</CODE>) and it is -always named <CODE>yy_globals</CODE>. As you may have guessed, -<CODE>yy_globals</CODE> is a pointer to an opaque data structure encapsulating +always named <CODE>yyscanner</CODE>. As you may have guessed, +<CODE>yyscanner</CODE> is a pointer to an opaque data structure encapsulating the current state of the scanner. For a list of function declarations, -see section <A HREF="flex.html#SEC35">Functions and Macros Available in Reentrant C Scanners</A>. Note that preprocessor macros, such as +see section <A HREF="flex.html#SEC41">Functions and Macros Available in Reentrant C Scanners</A>. Note that preprocessor macros, such as <CODE>BEGIN</CODE>, <CODE>ECHO</CODE>, and <CODE>REJECT</CODE>, do not take this additional argument. -<H3><A NAME="SEC29" HREF="flex_toc.html#TOC29">Global Variables Replaced By Macros</A></H3> +<H3><A NAME="SEC36" HREF="flex_toc.html#TOC36">Global Variables Replaced By Macros</A></H3> <P> -<A NAME="IDX247"></A> +<A NAME="IDX396"></A> All global variables in traditional flex have been replaced by macro equivalents. @@ -4091,7 +4376,7 @@ <PRE> @verbatim -#define yytext (((struct yy_globals_t*)yy_globals)->yytext_r) +#define yytext (((struct yyguts_t*)yyscanner)->yytext_r) </PRE> <P> @@ -4101,20 +4386,20 @@ <CODE>yytext</CODE> 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., -<CODE>yyget_text</CODE>, +other functions. You must use an accessor method, e.g., +<CODE>yyget_text</CODE>, to accomplish this. (See below). -<H3><A NAME="SEC30" HREF="flex_toc.html#TOC30">Init and Destroy Functions</A></H3> +<H3><A NAME="SEC37" HREF="flex_toc.html#TOC37">Init and Destroy Functions</A></H3> <P> -<A NAME="IDX248"></A> -<A NAME="IDX249"></A> -<A NAME="IDX250"></A> -<A NAME="IDX251"></A> +<A NAME="IDX397"></A> +<A NAME="IDX398"></A> +<A NAME="IDX399"></A> +<A NAME="IDX400"></A> <P> @@ -4126,8 +4411,8 @@ <PRE> @verbatim int yylex_init ( yyscan_t * ptr_yy_globals ) ; - int yylex ( yyscan_t yy_globals ) ; - int yylex_destroy ( yyscan_t yy_globals ) ; + int yylex ( yyscan_t yyscanner ) ; + int yylex_destroy ( yyscan_t yyscanner ) ; </PRE> <P> @@ -4142,13 +4427,28 @@ <CODE>yylex</CODE> should be familiar to you by now. The reentrant version takes one argument, which is the value returned (via an argument) by <CODE>yylex_init</CODE>. Otherwise, it behaves the same as the non-reentrant -version of <CODE>yylex</CODE>. +version of <CODE>yylex</CODE>. + + +<P> +<CODE>yylex_init</CODE> returns 0 (zero) on success, or non-zero on failure, +in which case, errno is set to one of the following values: + +<UL> +<LI>ENOMEM + +Memory allocation error. @xref{memory-management}. +<LI>EINVAL + +Invalid argument. +</UL> + <P> The function <CODE>yylex_destroy</CODE> should be called to free resources used by the scanner. After <CODE>yylex_destroy</CODE> -is called, the contents of <CODE>yy_globals</CODE> should not be used. Of +is called, the contents of <CODE>yyscanner</CODE> should not be used. Of course, there is no need to destroy a scanner if you plan to reuse it. A <CODE>flex</CODE> scanner (both reentrant and non-reentrant) may be restarted by calling <CODE>yyrestart</CODE>. @@ -4179,10 +4479,10 @@ -<H3><A NAME="SEC31" HREF="flex_toc.html#TOC31">Accessing Variables with Reentrant Scanners</A></H3> +<H3><A NAME="SEC38" HREF="flex_toc.html#TOC38">Accessing Variables with Reentrant Scanners</A></H3> <P> -<A NAME="IDX252"></A> +<A NAME="IDX401"></A> Accessor methods (get/set functions) provide access to common <CODE>flex</CODE> variables. @@ -4200,15 +4500,15 @@ <P> -<A NAME="IDX253"></A> +<A NAME="IDX402"></A> <PRE> @verbatim /* Set the last character of yytext to NULL. */ void chop ( yyscan_t scanner ) { - int len = yyget_leng( scanner ); - yyget_text( scanner )[len - 1] = '\0'; + int len = yyget_leng( scanner ); + yyget_text( scanner )[len - 1] = '\0'; } </PRE> @@ -4220,16 +4520,21 @@ <PRE> @verbatim %% - .+\n { chop( yy_globals );} + .+\n { chop( yyscanner );} </PRE> +<P> +You may find that <CODE>%option header-file</CODE> is particularly useful for generating +prototypes of all the accessor functions. @xref{option-header}. + -<H3><A NAME="SEC32" HREF="flex_toc.html#TOC32">Extra Data</A></H3> + +<H3><A NAME="SEC39" HREF="flex_toc.html#TOC39">Extra Data</A></H3> <P> -<A NAME="IDX254"></A> -<A NAME="IDX255"></A> +<A NAME="IDX403"></A> +<A NAME="IDX404"></A> User-specific data can be stored in <CODE>yyextra</CODE>. @@ -4253,9 +4558,9 @@ <P> -<A NAME="IDX256"></A> -<A NAME="IDX257"></A> -<A NAME="IDX258"></A> +<A NAME="IDX405"></A> +<A NAME="IDX406"></A> +<A NAME="IDX407"></A> <PRE> @verbatim @@ -4273,19 +4578,19 @@ <P> -<A NAME="IDX259"></A> +<A NAME="IDX408"></A> <PRE> @verbatim /* An example of overriding YY_EXTRA_TYPE. */ - %{ + %{ #include <sys/stat.h> #include <unistd.h> #define YY_EXTRA_TYPE struct stat* %} %option reentrant %% - + __filesize__ printf( "%ld", yyextra->st_size ); __lastmod__ printf( "%ld", yyextra->st_mtime ); %% @@ -4293,10 +4598,10 @@ { yyscan_t scanner; struct stat buf; - + yylex_init ( &scanner ); yyset_in( fopen(filename,"r"), scanner ); - + stat( filename, &buf); yyset_extra( &buf, scanner ); yylex ( scanner ); @@ -4306,10 +4611,10 @@ -<H3><A NAME="SEC33" HREF="flex_toc.html#TOC33">About yyscan_t</A></H3> +<H3><A NAME="SEC40" HREF="flex_toc.html#TOC40">About yyscan_t</A></H3> <P> -<A NAME="IDX260"></A> +<A NAME="IDX409"></A> <CODE>yyscan_t</CODE> is defined as: @@ -4328,156 +4633,25 @@ -<H2><A NAME="SEC34" HREF="flex_toc.html#TOC34">Reentrant C Scanners with Bison Pure Parsers</A></H2> - -<P> -<A NAME="IDX261"></A> -<A NAME="IDX262"></A> -<A NAME="IDX263"></A> -<A NAME="IDX264"></A> -<A NAME="IDX265"></A> - - -<P> -This section describes the <CODE>flex</CODE> features useful when integrating -<CODE>flex</CODE> with <CODE>GNU bison</CODE><A NAME="DOCF1" HREF="flex_foot.html#FOOT1">(1)</A>. -Skip this section if you are not using -<CODE>bison</CODE> with your scanner. Here we discuss only the <CODE>flex</CODE> -half of the <CODE>flex</CODE> and <CODE>bison</CODE> pair. We do not discuss -<CODE>bison</CODE> in any detail. For more information about generating pure -<CODE>bison</CODE> parsers, see section `Top' in <CITE>the GNU Bison Manual</CITE>. - - -<P> -A <CODE>bison</CODE>-compatible scanner is generated by declaring <SAMP>`%option -reentrant-bison'</SAMP> or by supplying <SAMP>`--reentrant-bison'</SAMP> when invoking <CODE>flex</CODE> -from the command line. This instructs <CODE>flex</CODE> that the macros -<CODE>yylval</CODE> and <CODE>yylloc</CODE> may be used. The data types for -<CODE>yylval</CODE> and <CODE>yylloc</CODE>, (<CODE>YYSTYPE</CODE> and <CODE>YYLTYPE</CODE>, -are typically defined in a header file, included in section 1 of the -<CODE>flex</CODE> input file. <CODE>%option reentrant-bison</CODE> implies -<CODE>%option reentrant</CODE>. If <CODE>%option reentrant-bison</CODE> is -specified, <CODE>flex</CODE> provides support for the functions -<CODE>yyget_lval</CODE>, <CODE>yyset_lval</CODE>, <CODE>yyget_lloc</CODE>, and -<CODE>yyset_lloc</CODE>, defined below, and the corresponding macros -<CODE>yylval</CODE> and <CODE>yylloc</CODE>, for use within actions. - - -<P> -<DL> -<DT><U>Function:</U> YYSTYPE* <B>yyget_lval</B> <I>( yyscan_t scanner )</I> -<DD><A NAME="IDX266"></A> -</DL> -<DL> -<DT><U>Function:</U> YYLTYPE* <B>yyget_lloc</B> <I>( yyscan_t scanner )</I> -<DD><A NAME="IDX267"></A> -</DL> - - -<P> -<DL> -<DT><U>Function:</U> void <B>yyset_lval</B> <I>( YYSTYPE* lvalp, yyscan_t scanner )</I> -<DD><A NAME="IDX268"></A> -</DL> -<DL> -<DT><U>Function:</U> void <B>yyset_lloc</B> <I>( YYLTYPE* llocp, yyscan_t scanner )</I> -<DD><A NAME="IDX269"></A> -</DL> - - -<P> -Accordingly, the declaration of yylex becomes one of the following: - - -<P> -<A NAME="IDX270"></A> - -<PRE> -@verbatim - int yylex ( YYSTYPE * lvalp, yyscan_t scanner ); - int yylex ( YYSTYPE * lvalp, YYLTYPE * llocp, yyscan_t scanner ); -</PRE> - -<P> -Note that the macros <CODE>yylval</CODE> and <CODE>yylloc</CODE> evaluate to -pointers. Support for <CODE>yylloc</CODE> is optional in <CODE>bison</CODE>, so it -is optional in <CODE>flex</CODE> as well. This support is automatically -handled by <CODE>flex</CODE>. Specifically, support for <CODE>yyloc</CODE> is only -present in a <CODE>flex</CODE> scanner if the preprocessor symbol -<CODE>YYLTYPE</CODE> is defined. The following is an example of a <CODE>flex</CODE> -scanner that is <CODE>bison</CODE>-compatible. - - -<P> -<A NAME="IDX271"></A> - -<PRE> -@verbatim - /* Scanner for "C" assignment statements... sort of. */ - %{ - #include "y.tab.h" /* Generated by bison. */ - %} - - %option reentrant-bison - % - - [[:digit:]]+ { yylval->num = atoi(yytext); return NUMBER;} - [[:alnum:]]+ { yylval->str = strdup(yytext); return STRING;} - "="|";" { return yytext[0];} - . {} - % -</PRE> - -<P> -As you can see, there really is no magic here. We just use -<CODE>yylval</CODE> as we would any other variable. The data type of -<CODE>yylval</CODE> is generated by <CODE>bison</CODE>, and included in the file -<TT>`y.tab.h'</TT>. Here is the corresponding <CODE>bison</CODE> parser: - - -<P> -<A NAME="IDX272"></A> - -<PRE> -@verbatim - /* Parser to convert "C" assignments to lisp. */ - %{ - /* Pass the argument to yyparse through to yylex. */ - #define YYPARSE_PARAM scanner - #define YYLEX_PARAM scanner - %} - %pure_parser - %union { - int num; - char* str; - } - %token <str> STRING - %token <num> NUMBER - %% - assignment: - STRING '=' NUMBER ';' { - printf( "(setf %s %d)", $1, $3 ); - } - ; -</PRE> - - - -<H2><A NAME="SEC35" HREF="flex_toc.html#TOC35">Functions and Macros Available in Reentrant C Scanners</A></H2> +<H2><A NAME="SEC41" HREF="flex_toc.html#TOC41">Functions and Macros Available in Reentrant C Scanners</A></H2> <P> The following Functions are available in a reentrant scanner: <P> -<A NAME="IDX273"></A> -<A NAME="IDX274"></A> -<A NAME="IDX275"></A> -<A NAME="IDX276"></A> -<A NAME="IDX277"></A> -<A NAME="IDX278"></A> -<A NAME="IDX279"></A> -<A NAME="IDX280"></A> +<A NAME="IDX410"></A> +<A NAME="IDX411"></A> +<A NAME="IDX412"></A> +<A NAME="IDX413"></A> +<A NAME="IDX414"></A> +<A NAME="IDX415"></A> +<A NAME="IDX416"></A> +<A NAME="IDX417"></A> +<A NAME="IDX418"></A> +<A NAME="IDX419"></A> +<A NAME="IDX420"></A> +<A NAME="IDX421"></A> @@ -4489,7 +4663,9 @@ FILE *yyget_out ( yyscan_t scanner ); int yyget_lineno ( yyscan_t scanner ); YY_EXTRA_TYPE yyget_extra ( yyscan_t scanner ); + int yyget_debug ( yyscan_t scanner ); + void yyset_debug ( int flag, yyscan_t scanner ); void yyset_in ( FILE * in_str , yyscan_t scanner ); void yyset_out ( FILE * out_str , yyscan_t scanner ); void yyset_lineno ( int line_number , yyscan_t scanner ); @@ -4514,10 +4690,11 @@ yyout yylineno yyextra + yy_flex_debug </PRE> <P> -<A NAME="IDX281"></A> +<A NAME="IDX422"></A> In a reentrant C scanner, support for yylineno is always present (i.e., you may access yylineno), but the value is never modified by <CODE>flex</CODE> unless <CODE>%option yylineno</CODE> is enabled. This is to allow @@ -4526,7 +4703,7 @@ <P> The following functions and macros are made available when <CODE>%option -reentrant-bison</CODE> (<SAMP>`--reentrant-bison'</SAMP>) is specified: +bison-bridge</CODE> (<SAMP>`--bison-bridge'</SAMP>) is specified: @@ -4550,11 +4727,11 @@ -<H1><A NAME="SEC36" HREF="flex_toc.html#TOC36">Incompatibilities with Lex and Posix</A></H1> +<H1><A NAME="SEC42" HREF="flex_toc.html#TOC42">Incompatibilities with Lex and Posix</A></H1> <P> -<A NAME="IDX282"></A> -<A NAME="IDX283"></A> +<A NAME="IDX423"></A> +<A NAME="IDX424"></A> <P> @@ -4622,7 +4799,7 @@ which long-jumps out of the scanner, and the scanner is subsequently called again, you may get the following message: -<A NAME="IDX284"></A> +<A NAME="IDX425"></A> <PRE> @verbatim @@ -4631,7 +4808,7 @@ To reenter the scanner, first use: -<A NAME="IDX285"></A> +<A NAME="IDX426"></A> <PRE> @verbatim @@ -4639,7 +4816,7 @@ </PRE> Note that this call will throw away any buffered input; usually this -isn't a problem with an interactive scanner. See section <A HREF="flex.html#SEC22">Reentrant C Scanners</A>, for +isn't a problem with an interactive scanner. See section <A HREF="flex.html#SEC29">Reentrant C Scanners</A>, for <CODE>flex</CODE>'s reentrant API. <LI> @@ -4647,7 +4824,7 @@ Also note that <CODE>flex</CODE> C++ scanner classes <EM>are</EM> reentrant, so if using C++ is an option for you, you should use -them instead. See section <A HREF="flex.html#SEC21">Generating C++ Scanners</A>, and section <A HREF="flex.html#SEC22">Reentrant C Scanners</A> for details. +them instead. See section <A HREF="flex.html#SEC28">Generating C++ Scanners</A>, and section <A HREF="flex.html#SEC29">Reentrant C Scanners</A> for details. <LI> @@ -4668,7 +4845,7 @@ When definitions are expanded, <CODE>flex</CODE> encloses them in parentheses. With <CODE>lex</CODE>, the following: -<A NAME="IDX286"></A> +<A NAME="IDX427"></A> <PRE> @verbatim @@ -4706,7 +4883,7 @@ Some implementations of <CODE>lex</CODE> allow a rule's action to begin on a separate line, if the rule's pattern has trailing whitespace: -<A NAME="IDX287"></A> +<A NAME="IDX428"></A> <PRE> @verbatim @@ -4756,48 +4933,88 @@ The name <CODE>FLEX_SCANNER</CODE> is <CODE>#define</CODE>'d so scanners may be written for use with either <CODE>flex</CODE> or <CODE>lex</CODE>. Scanners also -include <CODE>YY_FLEX_MAJOR_VERSION</CODE> and <CODE>YY_FLEX_MINOR_VERSION</CODE> -indicating which version of <CODE>flex</CODE> generated the scanner (for -example, for the 2.5 release, these defines would be 2 and 5 -respectively). +include <CODE>YY_FLEX_MAJOR_VERSION</CODE>, <CODE>YY_FLEX_MINOR_VERSION</CODE> +and <CODE>YY_FLEX_SUBMINOR_VERSION</CODE> +indicating which version of <CODE>flex</CODE> generated the scanner. For +example, for the 2.5.22 release, these defines would be 2, 5 and 22 +respectively. If the version of <CODE>flex</CODE> being used is a beta +version, then the symbol <CODE>FLEX_BETA</CODE> is defined. </UL> <P> -<A NAME="IDX288"></A> - - -<P> +<A NAME="IDX429"></A> +<A NAME="IDX430"></A> The following <CODE>flex</CODE> features are not included in <CODE>lex</CODE> or the POSIX specification: -<PRE> -@verbatim - 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() +<UL> +<LI> + +C++ scanners +<LI> + +%option +<LI> + +start condition scopes +<LI> + +start condition stacks +<LI> + +interactive/non-interactive scanners +<LI> + +yy_scan_string() and friends +<LI> + +yyterminate() +<LI> + +yy_set_interactive() +<LI> + +yy_set_bol() +<LI> + +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 -</PRE> +<LI> + +<*> +<LI> + +YY_DECL +<LI> + +YY_START +<LI> + +YY_USER_ACTION +<LI> + +YY_USER_INIT +<LI> + +#line directives +<LI> + +%{}'s around actions +<LI> + +reentrant C API +<LI> + +multiple actions on a line +<LI> + +almost all of the <CODE>flex</CODE> command-line options +</UL> <P> -plus almost all of the <CODE>flex</CODE> flags. The last feature in the list +The feature "multiple actions on a line" refers to the fact that with <CODE>flex</CODE> you can put multiple actions on the same line, separated with semi-colons, while with <CODE>lex</CODE>, the following: @@ -4826,11 +5043,577 @@ -<H1><A NAME="SEC37" HREF="flex_toc.html#TOC37">Diagnostics</A></H1> +<H1><A NAME="SEC43" HREF="flex_toc.html#TOC43">Memory Management</A></H1> <P> -<A NAME="IDX289"></A> -<A NAME="IDX290"></A> +<A NAME="IDX431"></A> +@anchor{memory-management} +This chapter describes how flex handles dynamic memory, and how you can +override the default behavior. + + + + +<H2><A NAME="SEC44" HREF="flex_toc.html#TOC44">The Default Memory Management</A></H2> + +<P> +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 <CODE>yylex_destroy</CODE> +@xref{faq-memory-leak}. + + +<P> +Flex allocates dynamic memory for four purposes, listed below <A NAME="DOCF1" HREF="flex_foot.html#FOOT1">(1)</A> + + +<DL COMPACT> + +<DT>16kB for the input buffer. +<DD> +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. Flex will allocate a few +extra bytes for housekeeping. + +<DT>16kb for the REJECT state. This will only be allocated if you use REJECT. +<DD> +The size is the same as the input buffer, so if you override the size of the +input buffer, then you automatically override the size of this buffer as well. + +<DT>100 bytes for the start condition stack. +<DD> +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 <CODE>%option stack</CODE> 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(). @xref{option-stack}. + +<DT>40 bytes for each YY_BUFFER_STATE. +<DD> +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 <EM>NOT</EM> 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. +See section <A HREF="flex.html#SEC15">Multiple Input Buffers</A>. + +<DT>84 bytes for the reentrant scanner guts +<DD> +Flex allocates about 84 bytes for the reentrant scanner structure when +you call yylex_init(). It is destroyed when the user calls yylex_destroy(). + +</DL> + + + +<H2><A NAME="SEC45" HREF="flex_toc.html#TOC45">Overriding The Default Memory Management</A></H2> + +<P> +<A NAME="IDX432"></A> +<A NAME="IDX433"></A> +<A NAME="IDX434"></A> + + +<P> +Flex calls the functions <CODE>yyalloc</CODE>, <CODE>yyrealloc</CODE>, and <CODE>yyfree</CODE> +when it needs to allocate or free memory. By default, these functions are +wrappers around the standard C functions, <CODE>malloc</CODE>, <CODE>realloc</CODE>, and +<CODE>free</CODE>, respectively. You can override the default implementations by telling +flex that you will provide your own implementations. + + +<P> +To override the default implementations, you must do two things: + + + +<OL> + +<LI>Suppress the default implementations by specifying one or more of the + +following options: + + +<UL> +<LI><CODE>%option noyyalloc</CODE> + +<A NAME="IDX435"></A> + +<LI><CODE>%option noyyrealloc</CODE> + +<LI><CODE>%option noyyfree</CODE>. + +</UL> + +<LI>Provide your own implementation of the following functions: <A NAME="DOCF2" HREF="flex_foot.html#FOOT2">(2)</A> + + +<PRE> +@verbatim +// For a non-reentrant scanner +void * yyalloc (size_t bytes); +void * yyrealloc (void * ptr, size_t bytes); +void yyfree (void * ptr); + +// For a reentrant scanner +void * yyalloc (size_t bytes, void * yyscanner); +void * yyrealloc (void * ptr, size_t bytes, void * yyscanner); +void yyfree (void * ptr, void * yyscanner); +</PRE> + +</OL> + +<P> +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 <CODE>yyextra</CODE>. + + +<P> +<A NAME="IDX436"></A> + +<PRE> +@verbatim +%{ +#include "some_allocator.h" +%} + +/* Suppress the default implementations. */ +%option noyyalloc noyyrealloc noyyfree +%option reentrant + +/* Initialize the allocator. */ +#define YY_EXTRA_TYPE struct allocator* +#define YY_USER_INIT yyextra = allocator_create(); + +%% +.|\n ; +%% + +/* Provide our own implementations. */ +void * yyalloc (size_t bytes, void* yyscanner) { + return allocator_alloc (yyextra, bytes); +} + +void * yyrealloc (void * ptr, size_t bytes, void* yyscanner) { + return allocator_realloc (yyextra, bytes); +} + +void yyfree (void * ptr, void * yyscanner) { + /* Do nothing -- we leave it to the garbage collector. */ +} + +</PRE> + + + +<H2><A NAME="SEC46" HREF="flex_toc.html#TOC46">A Note About yytext And Memory</A></H2> + +<P> +<A NAME="IDX437"></A> + + +<P> +When flex finds a match, <CODE>yytext</CODE> points to the first character of the +match in the input buffer. The string itself is part of the input buffer, and +is <EM>NOT</EM> 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. + + +<P> +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 introduces some headache +because your parser is now responsible for 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. + + +<P> +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. + + + + +<H1><A NAME="SEC47" HREF="flex_toc.html#TOC47">Serialized Tables</A></H1> +<P> +<A NAME="IDX438"></A> +<A NAME="IDX439"></A> + + +<P> +@anchor{serialization} +A <CODE>flex</CODE> 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. + + +<P> +The serialization feature allows the tables to be loaded at runtime, before +scanning begins. The tables may be discarded when scanning is finished. + + + + +<H2><A NAME="SEC48" HREF="flex_toc.html#TOC48">Creating Serialized Tables</A></H2> +<P> +<A NAME="IDX440"></A> +<A NAME="IDX441"></A> + + +<P> +You may create a scanner with serialized tables by specifying: + + + +<PRE> +@verbatim + %option tables-file=FILE +or + --tables-file=FILE +</PRE> + +<P> +These options instruct flex to save the DFA tables to the file <VAR>FILE</VAR>. The tables +will <EM>not</EM> 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. + + +<P> +If you do not specify a filename to <CODE>--tables-file</CODE>, the tables will be +saved to <TT>`lex.yy.tables'</TT>, where <SAMP>`yy'</SAMP> is the appropriate prefix. + + +<P> +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 example follows: + + +<P> +<A NAME="IDX442"></A> + +<PRE> +@verbatim +$ flex --tables-file --prefix=cpp cpp.l +$ flex --tables-file --prefix=c c.l +$ cat lex.cpp.tables lex.c.tables > all.tables +</PRE> + +<P> +The above example created two scanners, <SAMP>`cpp'</SAMP>, and <SAMP>`c'</SAMP>. Since we did +not specify a filename, the tables were serialized to <TT>`lex.c.tables'</TT> and +<TT>`lex.cpp.tables'</TT>, respectively. Then, we concatenated the two files +together into <TT>`all.tables'</TT>, 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 section). + + + + +<H2><A NAME="SEC49" HREF="flex_toc.html#TOC49">Loading and Unloading Serialized Tables</A></H2> +<P> +<A NAME="IDX443"></A> +<A NAME="IDX444"></A> +<A NAME="IDX445"></A> +<A NAME="IDX446"></A> +<A NAME="IDX447"></A> + + +<P> +If you've built your scanner with <CODE>%option tables-file</CODE>, then you must +load the scanner tables at runtime. This can be accomplished with the following +function: + + +<P> +<DL> +<DT><U>Function:</U> int <B>yytables_fload</B> <I>(FILE* <VAR>fp</VAR> [, yyscan_t <VAR>scanner</VAR>])</I> +<DD><A NAME="IDX448"></A> +Locates scanner tables in the stream pointed to by <VAR>fp</VAR> and loads them. +Memory for the tables is allocated via <CODE>yyalloc</CODE>. You must call this +function before the first call to <CODE>yylex</CODE>. The argument <VAR>scanner</VAR> +only appears in the reentrant scanner. +This function returns <SAMP>`0'</SAMP> (zero) on success, or non-zero on error. +</DL> + + +<P> +The loaded tables are <STRONG>not</STRONG> automatically destroyed (unloaded) when you +call <CODE>yylex_destroy</CODE>. 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: + + +<P> +<DL> +<DT><U>Function:</U> int <B>yytables_destroy</B> <I>([yyscan_t <VAR>scanner</VAR>])</I> +<DD><A NAME="IDX449"></A> +Unloads the scanner tables. The tables must be loaded again before you can scan +any more data. The argument <VAR>scanner</VAR> only appears in the reentrant +scanner. This function returns <SAMP>`0'</SAMP> (zero) on success, or non-zero on +error. +</DL> + + +<P> +<STRONG>The functions <CODE>yytables_fload</CODE> and <CODE>yytables_destroy</CODE> are not +thread-safe.</STRONG> You must ensure that these functions are called exactly once (for +each scanner type) in a threaded program, before any thread calls <CODE>yylex</CODE>. +After the tables are loaded, they are never written to, and no thread +protection is required thereafter -- until you destroy them. + + + + +<H2><A NAME="SEC50" HREF="flex_toc.html#TOC50">Tables File Format</A></H2> +<P> +<A NAME="IDX450"></A> +<A NAME="IDX451"></A> + + +<P> +This section defines the file format of serialized <CODE>flex</CODE> tables. + + +<P> +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: + + + +<PRE> +@verbatim + TABLE SET 1 + +-------------------------------+ + Header | uint32 th_magic; | + | uint32 th_hsize; | + | uint32 th_ssize; | + | uint16 th_flags; | + | char th_version[]; | + | char th_name[]; | + | uint8 th_pad64[]; | + +-------------------------------+ + Table 1 | uint16 td_id; | + | uint16 td_flags; | + | uint32 td_lolen; | + | uint32 td_hilen; | + | void td_data[]; | + | uint8 td_pad64[]; | + +-------------------------------+ + Table 2 | | + . . . + . . . + . . . + . . . + Table n | | + +-------------------------------+ + TABLE SET 2 + . + . + . + TABLE SET N +</PRE> + +<P> +The above diagram shows that a complete set of tables consists of a 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 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, <EM>all integer values are in network byte order</EM>. + + +<P> +Fields of a table header: + + +<DL COMPACT> + +<DT><CODE>th_magic</CODE> +<DD> +Magic number, always 0xF13C57B1. + +<DT><CODE>th_hsize</CODE> +<DD> +Size of this entire header, in bytes, including all fields plus any padding. + +<DT><CODE>th_ssize</CODE> +<DD> +Size of this entire set, in bytes, including the header, all tables, plus +any padding. + +<DT><CODE>th_flags</CODE> +<DD> +Bit flags for this table set. Currently unused. + +<DT><CODE>th_version[]</CODE> +<DD> +Flex version in NULL-termninated string format. e.g., <SAMP>`2.5.13a'</SAMP>. This is +the version of flex that was used to create the serialized tables. + +<DT><CODE>th_name[]</CODE> +<DD> +Contains the name of this table set. The default is <SAMP>`yytables'</SAMP>, +and is prefixed accordingly, e.g., <SAMP>`footables'</SAMP>. Must be NULL-terminated. + +<DT><CODE>th_pad64[]</CODE> +<DD> +Zero or more NULL bytes, padding the entire header to the next 64-bit boundary +as calculated from the beginning of the header. +</DL> + +<P> +Fields of a table: + + +<DL COMPACT> + +<DT><CODE>td_id</CODE> +<DD> +Specifies the table identifier. Possible values are: +<DL COMPACT> + +<DT><CODE>YYTD_ID_ACCEPT (0x01)</CODE> +<DD> +<CODE>yy_accept</CODE> +<DT><CODE>YYTD_ID_BASE (0x02)</CODE> +<DD> +<CODE>yy_base</CODE> +<DT><CODE>YYTD_ID_CHK (0x03)</CODE> +<DD> +<CODE>yy_chk</CODE> +<DT><CODE>YYTD_ID_DEF (0x04)</CODE> +<DD> +<CODE>yy_def</CODE> +<DT><CODE>YYTD_ID_EC (0x05)</CODE> +<DD> +<CODE>yy_ec </CODE> +<DT><CODE>YYTD_ID_META (0x06)</CODE> +<DD> +<CODE>yy_meta</CODE> +<DT><CODE>YYTD_ID_NUL_TRANS (0x07)</CODE> +<DD> +<CODE>yy_NUL_trans</CODE> +<DT><CODE>YYTD_ID_NXT (0x08)</CODE> +<DD> +<CODE>yy_nxt</CODE>. This array may be two dimensional. See the <CODE>td_hilen</CODE> +field below. +<DT><CODE>YYTD_ID_RULE_CAN_MATCH_EOL (0x09)</CODE> +<DD> +<CODE>yy_rule_can_match_eol</CODE> +<DT><CODE>YYTD_ID_START_STATE_LIST (0x0A)</CODE> +<DD> +<CODE>yy_start_state_list</CODE>. This array is handled specially because it is an +array of pointers to structs. See the <CODE>td_flags</CODE> field below. +<DT><CODE>YYTD_ID_TRANSITION (0x0B)</CODE> +<DD> +<CODE>yy_transition</CODE>. This array is handled specially because it is an array of +structs. See the <CODE>td_lolen</CODE> field below. +<DT><CODE>YYTD_ID_ACCLIST (0x0C)</CODE> +<DD> +<CODE>yy_acclist</CODE> +</DL> + +<DT><CODE>td_flags</CODE> +<DD> +Bit flags describing how to interpret the data in <CODE>td_data</CODE>. +The data arrays are one-dimensional by default, but may be +two dimensional as specified in the <CODE>td_hilen</CODE> field. + +<DL COMPACT> + +<DT><CODE>YYTD_DATA8 (0x01)</CODE> +<DD> +The data is serialized as an array of type int8. +<DT><CODE>YYTD_DATA16 (0x02)</CODE> +<DD> +The data is serialized as an array of type int16. +<DT><CODE>YYTD_DATA32 (0x04)</CODE> +<DD> +The data is serialized as an array of type int32. +<DT><CODE>YYTD_PTRANS (0x08)</CODE> +<DD> +The data is a list of indexes of entries in the expanded <CODE>yy_transition</CODE> +array. Each index should be expanded to a pointer to the corresponding entry +in the <CODE>yy_transition</CODE> array. We count on the fact that the +<CODE>yy_transition</CODE> array has already been seen. +<DT><CODE>YYTD_STRUCT (0x10)</CODE> +<DD> +The data is a list of yy_trans_info structs, each of which consists of +two integers. There is no padding between struct elements or between structs. +The type of each member is determined by the <CODE>YYTD_DATA*</CODE> bits. +</DL> + +<DT><CODE>td_lolen</CODE> +<DD> +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 <CODE>td_flags</CODE> field. + +<DT><CODE>td_hilen</CODE> +<DD> +If <CODE>td_hilen</CODE> is non-zero, then the data is a two-dimensional array. +Otherwise, the data is a one-dimensional array. <CODE>td_hilen</CODE> contains the +number of elements in the higher dimensional array, and <CODE>td_lolen</CODE> contains +the number of elements in the lowest dimension. + +Conceptually, <CODE>td_data</CODE> is either <CODE>sometype td_data[td_lolen]</CODE>, or +<CODE>sometype td_data[td_hilen][td_lolen]</CODE>, where <CODE>sometype</CODE> is specified +by the <CODE>td_flags</CODE> field. It is possible for both <CODE>td_lolen</CODE> and +<CODE>td_hilen</CODE> to be zero, in which case <CODE>td_data</CODE> 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 length. + +<DT><CODE>td_data[]</CODE> +<DD> +The table data. This array may be a one- or two-dimensional array, of type +<CODE>int8</CODE>, <CODE>int16</CODE>, <CODE>int32</CODE>, <CODE>struct yy_trans_info</CODE>, or +<CODE>struct yy_trans_info*</CODE>, depending upon the values in the +<CODE>td_flags</CODE>, <CODE>td_lolen</CODE>, and <CODE>td_hilen</CODE> fields. + +<DT><CODE>td_pad64[]</CODE> +<DD> +Zero or more NULL bytes, padding the entire table to the next 64-bit boundary as +calculated from the beginning of this table. +</DL> + + + +<H1><A NAME="SEC51" HREF="flex_toc.html#TOC51">Diagnostics</A></H1> + +<P> +<A NAME="IDX452"></A> +<A NAME="IDX453"></A> <P> @@ -4846,7 +5629,7 @@ the same text as it. For example, in the following <SAMP>`foo'</SAMP> cannot be matched because it comes after an identifier "catch-all" rule: -<A NAME="IDX291"></A> +<A NAME="IDX454"></A> <PRE> @verbatim @@ -4862,7 +5645,7 @@ 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 <SAMP>`-s'</SAMP> was given, presumably this is -not intended. +not intended. <LI> @@ -4896,7 +5679,7 @@ specification includes recognizing the 8-bit character <SAMP>`'x''</SAMP> and you did not specify the -8 flag, and your scanner defaulted to 7-bit because you used the <SAMP>`-Cf'</SAMP> or <SAMP>`-CF'</SAMP> table compression options. -See the discussion of the <SAMP>`-7'</SAMP> flag, section <A HREF="flex.html#SEC18">Invoking Flex</A>, for +See the discussion of the <SAMP>`-7'</SAMP> flag, section <A HREF="flex.html#SEC20">Scanner Options</A>, for details. <LI> @@ -4937,10 +5720,10 @@ -<H1><A NAME="SEC38" HREF="flex_toc.html#TOC38">Limitations</A></H1> +<H1><A NAME="SEC52" HREF="flex_toc.html#TOC52">Limitations</A></H1> <P> -<A NAME="IDX292"></A> +<A NAME="IDX455"></A> <P> @@ -4960,7 +5743,7 @@ <P> -<A NAME="IDX293"></A> +<A NAME="IDX456"></A> <PRE> @verbatim @@ -4992,7 +5775,7 @@ -<H1><A NAME="SEC39" HREF="flex_toc.html#TOC39">Additional Reading</A></H1> +<H1><A NAME="SEC53" HREF="flex_toc.html#TOC53">Additional Reading</A></H1> <P> You may wish to read more about the following programs: @@ -5032,107 +5815,28 @@ -<H1><A NAME="SEC40" HREF="flex_toc.html#TOC40">Copyright</A></H1> - -<P> -<A NAME="IDX294"></A> -<A NAME="IDX295"></A> - - -<P> -The flex manual is placed under the same licensing conditions as the -rest of flex: - - -<P> -Copyright (C) 1990, 1997 The Regents of the University of California. -All rights reserved. - +<H1><A NAME="SEC54" HREF="flex_toc.html#TOC54">FAQ</A></H1> <P> -This code is derived from software contributed to Berkeley by -Vern Paxson. - +From time to time, the <CODE>flex</CODE> maintainer receives certain +questions. Rather than repeat answers to well-understood problems, we +publish them here. -<P> -The United States Government has rights in this work pursuant -to contract no. DE-AC03-76SF00098 between the United States -Department of Energy and the University of California. -<P> -Redistribution and use in source and binary forms, with or without -modification, are permitted provided that the following conditions -are met: - - - -<OL> -<LI> - -Redistributions of source code must retain the above copyright -notice, this list of conditions and the following disclaimer. - -<LI> - -Redistributions in binary form must reproduce the above copyright -notice, this list of conditions and the following disclaimer in the -documentation and/or other materials provided with the distribution. -</OL> - -<P> -Neither the name of the University nor the names of its contributors -may be used to endorse or promote products derived from this software -without specific prior written permission. - - -<P> -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. - - - - -<H1><A NAME="SEC41" HREF="flex_toc.html#TOC41">Reporting Bugs</A></H1> - -<P> -<A NAME="IDX296"></A> - - -<P> -If you have problems with <CODE>flex</CODE> or think you have found a bug, -please send mail detailing your problem to -<A HREF="mailto:help-flex@gnu.org">help-flex@gnu.org</A>. Patches are always welcome. - - - - -<H1><A NAME="SEC42" HREF="flex_toc.html#TOC42">FAQ</A></H1> - - - -<H2><A NAME="SEC43" HREF="flex_toc.html#TOC43">When was flex born?</A></H2> - -<P> -When was flex born? +<H2><A NAME="SEC55" HREF="flex_toc.html#TOC55">When was flex born?</A></H2> <P> Vern Paxson took over -the Software Tools lex project from Jef Poskanzer in 1982. At that point it +the <CITE>Software Tools</CITE> 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 :-). -<H2><A NAME="SEC44" HREF="flex_toc.html#TOC44">How do I expand \ escape sequences in C-style quoted strings?</A></H2> - -<P> -How do I expand \ escape sequences in C-style quoted strings? - +<H2><A NAME="SEC56" HREF="flex_toc.html#TOC56">How do I expand \ escape sequences in C-style quoted strings?</A></H2> <P> A key point when scanning quoted strings is that you cannot (easily) write @@ -5143,41 +5847,36 @@ <P> -Instead you use exclusive start conditions and a set of rules, one for +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" +append their local value of <CODE>yytext</CODE> 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. +meaning of the escape sequence rather than the literal text in <CODE>yytext</CODE>. +In this way, <CODE>yytext</CODE> does not need to be modified at all. -<H2><A NAME="SEC45" HREF="flex_toc.html#TOC45">Why do flex scanners call fileno if it is not ANSI compatible?</A></H2> +<H2><A NAME="SEC57" HREF="flex_toc.html#TOC57">Why do flex scanners call fileno if it is not ANSI compatible?</A></H2> <P> -Why do flex scanners call fileno if it is not ANSI compatible? +Flex scanners call <CODE>fileno()</CODE> in order to get the file descriptor +corresponding to <CODE>yyin</CODE>. The file descriptor may be passed to +<CODE>isatty()</CODE> or <CODE>read()</CODE>, depending upon which <CODE>%options</CODE> you specified. +If your system does not have <CODE>fileno()</CODE> support, to get rid of the +<CODE>read()</CODE> call, do not specify <CODE>%option read</CODE>. To get rid of the <CODE>isatty()</CODE> +call, you must specify one of <CODE>%option always-interactive</CODE> or +<CODE>%option never-interactive</CODE>. -<P> -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. - - -<H2><A NAME="SEC46" HREF="flex_toc.html#TOC46">Does flex support recursive pattern definitions?</A></H2> +<H2><A NAME="SEC58" HREF="flex_toc.html#TOC58">Does flex support recursive pattern definitions?</A></H2> <P> -Does flex support recursive pattern definitions? e.g., @@ -5189,39 +5888,31 @@ </PRE> <P> -No. You cannot have recursive definitions. The pattern-matching power of +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. - +as <CITE>GNU bison</CITE>. -<H2><A NAME="SEC47" HREF="flex_toc.html#TOC47">How do skip huge chunks of input (tens of megabytes) while using flex?</A></H2> - -<P> -How do skip huge chunks of input (tens of megabytes) while using flex? +<H2><A NAME="SEC59" HREF="flex_toc.html#TOC59">How do I skip huge chunks of input (tens of megabytes) while using flex?</A></H2> <P> -Use fseek (or lseek) to position yyin, then call yyrestart(). +Use <CODE>fseek()</CODE> (or <CODE>lseek()</CODE>) to position yyin, then call <CODE>yyrestart()</CODE>. -<H2><A NAME="SEC48" HREF="flex_toc.html#TOC48">Flex is not matching my patterns in the same order that I defined them.</A></H2> +<H2><A NAME="SEC60" HREF="flex_toc.html#TOC60">Flex is not matching my patterns in the same order that I defined them.</A></H2> <P> -Flex is not matching my patterns in the same order that I defined them. - - -<P> -This is indeed the natural way to expect it to work, however, flex picks the +<CODE>flex</CODE> 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 +This is because <CODE>flex</CODE> 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.) @@ -5229,13 +5920,12 @@ <P> 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 section "How the input -is Matched". +than one rule, <CODE>flex</CODE> scanners pick the rule that matched the <EM>most</EM> text. This +is explained further in the manual, in the section See section <A HREF="flex.html#SEC11">How the Input Is Matched</A>. <P> -If you want flex to choose a shorter match, then you can work around this +If you want <CODE>flex</CODE> 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: @@ -5248,26 +5938,21 @@ <P> 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. +<CODE><BLOCKIDSTATE></CODE> start condition, and make that start condition exclusive +by declaring it with <CODE>%x</CODE> instead of <CODE>%s</CODE>. <P> 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 -also not have the option of changing the input language ...) - +<SAMP>`data_'</SAMP> is removed, by adding characters to it that don't match the +identifier rule, or by removing characters (such as <SAMP>`_'</SAMP>) from the +identifier rule so it no longer matches <SAMP>`data_'</SAMP>. (Of course, you might +also not have the option of changing the input language.) -<H2><A NAME="SEC49" HREF="flex_toc.html#TOC49">My actions are executing out of order or sometimes not at all.</A></H2> - -<P> -My actions are executing out of order or sometimes not at all. What's -happening? +<H2><A NAME="SEC61" HREF="flex_toc.html#TOC61">My actions are executing out of order or sometimes not at all.</A></H2> <P> Most likely, you have (in error) placed the opening <SAMP>`{'</SAMP> of the action @@ -5278,13 +5963,13 @@ <PRE> @verbatim ^(foo|bar) - { <<<--- WRONG! +{ <<<--- WRONG! - } +} </PRE> <P> -flex requires that the opening <SAMP>`{'</SAMP> of an action associated with a rule +<CODE>flex</CODE> requires that the opening <SAMP>`{'</SAMP> 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: @@ -5294,79 +5979,70 @@ @verbatim ^(foo|bar) { // CORRECT! - } +} </PRE> -<H2><A NAME="SEC50" HREF="flex_toc.html#TOC50">How can I have multiple input sources feed into the same scanner at the same time?</A></H2> - -<P> -How can I have multiple input sources feed into the same scanner at -the same time? - +<H2><A NAME="SEC62" HREF="flex_toc.html#TOC62">How can I have multiple input sources feed into the same scanner at the same time?</A></H2> <P> -If... +If ... <UL> <LI> -your scanner is free of backtracking (verified using flex's -b flag), +your scanner is free of backtracking (verified using <CODE>flex</CODE>'s <SAMP>`-b'</SAMP> flag), <LI> -AND you run it interactively (-I option; default unless using special table +AND you run your scanner interactively (<SAMP>`-I'</SAMP> option; default unless using special table compression options), <LI> -AND you feed it one character at a time by redefining YY_INPUT to do so, +AND you feed it one character at a time by redefining <CODE>YY_INPUT</CODE> to do so, </UL> <P> 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 <CODE>select()</CODE> at the point and only call <CODE>yylex()</CODE> for another +token if <CODE>select()</CODE> indicates there's data available. <P> -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 <CODE>select()</CODE> out from the input function to a point where +it determines whether <CODE>yylex()</CODE> gets called for the next token. <P> 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 blocking waiting +piecemeal; <CODE>select()</CODE> could inform you that the beginning of a token is +available, you call <CODE>yylex()</CODE> to get it, but it winds up blocking waiting for the later characters in the token. <P> -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 +Here's another way: Move your input multiplexing inside of <CODE>YY_INPUT</CODE>. That +is, whenever <CODE>YY_INPUT</CODE> is called, it <CODE>select()</CODE>'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 is.) I've used this technique in an -interpreter I wrote that both reads keyboard input using a flex scanner and +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 <CODE>flex</CODE> scanner and IPC traffic from sockets, and it works fine. -<H2><A NAME="SEC51" HREF="flex_toc.html#TOC51">Can I build nested parsers that work with the same input file?</A></H2> - -<P> -Can I build nested parsers that work with the same input file? - +<H2><A NAME="SEC63" HREF="flex_toc.html#TOC63">Can I build nested parsers that work with the same input file?</A></H2> <P> 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 +that <CODE>flex</CODE> block-buffers the input it reads from <CODE>yyin</CODE>. This means that the +"outermost" <CODE>yylex()</CODE>, when called, will automatically slurp up the first 8K +of input available on yyin, and subsequent calls to other <CODE>yylex()</CODE>'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 +redefining <CODE>YY_INPUT</CODE> 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. @@ -5374,19 +6050,15 @@ -<H2><A NAME="SEC52" HREF="flex_toc.html#TOC52">How can I match text only at the end of a file?</A></H2> - -<P> -How can I match text only at the end of a file? - +<H2><A NAME="SEC64" HREF="flex_toc.html#TOC64">How can I match text only at the end of a file?</A></H2> <P> 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: +Then you redefine <CODE>YY_INPUT</CODE> to call your own routine which, if it sees +an <SAMP>`EOF'</SAMP>, returns the magic character first (and remembers to return a +real <CODE>EOF</CODE> next time it's called). Then you could write: @@ -5397,16 +6069,12 @@ -<H2><A NAME="SEC53" HREF="flex_toc.html#TOC53">How can I make REJECT cascade across start condition boundaries?</A></H2> - -<P> -How can I make REJECT cascade across start condition boundaries? - +<H2><A NAME="SEC65" HREF="flex_toc.html#TOC65">How can I make REJECT cascade across start condition boundaries?</A></H2> <P> -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 <SAMP>`A'</SAMP>, and +after exhausting all of the possible matches in <SAMP>`<A>'</SAMP>, you want to try +matches in <SAMP>`<INITIAL>'</SAMP>. Then you could use the following: @@ -5419,29 +6087,25 @@ <A>etc. ... <A>.|\n { - /* Shortest and last rule in <A>, so - * cascaded REJECT's will eventually - * wind up matching this rule. We want - * to now switch to the initial state - * and try matching from there instead. - */ - yyless(0); /* put back matched text */ - BEGIN(INITIAL); - } +/* Shortest and last rule in <A>, so +* cascaded REJECT's will eventually +* wind up matching this rule. We want +* to now switch to the initial state +* and try matching from there instead. +*/ +yyless(0); /* put back matched text */ +BEGIN(INITIAL); +} </PRE> -<H2><A NAME="SEC54" HREF="flex_toc.html#TOC54">Why can't I use fast or full tables with interactive mode?</A></H2> - -<P> -Why can't I use fast or full tables with interactive mode? - +<H2><A NAME="SEC66" HREF="flex_toc.html#TOC66">Why can't I use fast or full tables with interactive mode?</A></H2> <P> One of the assumptions -flex makes is that interactive applications are inherently slow (for just -that reason, they're waiting on a human). +flex makes is that interactive applications are inherently slow (they're +waiting on a human after all). It has to do with how the scanner detects that it must be finished scanning a token. For interactive scanners, after scanning each character the current state is looked up in a table (essentially) to see whether there's a chance @@ -5456,16 +6120,12 @@ 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 +interactive option. -<H2><A NAME="SEC55" HREF="flex_toc.html#TOC55">How much faster is -F or -f than -C?</A></H2> - -<P> -How much faster is -F or -f than -C? - +<H2><A NAME="SEC67" HREF="flex_toc.html#TOC67">How much faster is -F or -f than -C?</A></H2> <P> Much faster (factor of 2-3). @@ -5473,11 +6133,7 @@ -<H2><A NAME="SEC56" HREF="flex_toc.html#TOC56">If I have a simple grammar can't I just parse it with flex?</A></H2> - -<P> -If I have a simple grammar, can't I just parse it with flex? - +<H2><A NAME="SEC68" HREF="flex_toc.html#TOC68">If I have a simple grammar can't I just parse it with flex?</A></H2> <P> Is your grammar recursive? That's almost always a sign that you're @@ -5485,26 +6141,20 @@ alone. -<H2><A NAME="SEC57" HREF="flex_toc.html#TOC57">Why doesn't yyrestart() set the start state back to INITIAL?</A></H2> -<P> -Why doesn't yyrestart() set the start state back to INITIAL? +<H2><A NAME="SEC69" HREF="flex_toc.html#TOC69">Why doesn't yyrestart() set the start state back to INITIAL?</A></H2> <P> 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 with flex 2.4, use of yyrestart() is no longer required, -so fixing the problem there doesn't solve the more general problem. - +The second is that beginning with <CODE>flex</CODE> version 2.4, use of <CODE>yyrestart()</CODE> is no longer required, +so fixing the problem there doesn't solve the more general problem. -<H2><A NAME="SEC58" HREF="flex_toc.html#TOC58">How can I match C-style comments?</A></H2> - -<P> -How can I match C-style comments? +<H2><A NAME="SEC70" HREF="flex_toc.html#TOC70">How can I match C-style comments?</A></H2> <P> You might be tempted to try something like this: @@ -5533,7 +6183,7 @@ <PRE> @verbatim - /* a comment */ do_my_thing( "oops */" ); +/* a comment */ do_my_thing( "oops */" ); </PRE> <P> @@ -5544,23 +6194,19 @@ <PRE> @verbatim <INITIAL>{ - "/*" BEGIN(IN_COMMENT); +"/*" BEGIN(IN_COMMENT); } <IN_COMMENT>{ - "*/" BEGIN(INITIAL); - [^*\n]+ // eat comment in chunks - "*" // eat the lone star - \n yylineno++; +"*/" BEGIN(INITIAL); +[^*\n]+ // eat comment in chunks +"*" // eat the lone star +\n yylineno++; } </PRE> -<H2><A NAME="SEC59" HREF="flex_toc.html#TOC59">The '.' isn't working the way I expected.</A></H2> - -<P> -The '.' (dot) isn't working the way I expected. - +<H2><A NAME="SEC71" HREF="flex_toc.html#TOC71">The '.' isn't working the way I expected.</A></H2> <P> Here are some tips for using <SAMP>`.'</SAMP>: @@ -5574,47 +6220,37 @@ you really meant to place the parenthesis BEFORE the operator, e.g., you probably want this <CODE>(foo|bar)+</CODE> and NOT this <CODE>(foo|bar+)</CODE>. -The first pattern matches the words <CODE>foo</CODE> or <CODE>bar</CODE> any number of -times, e.g., it matches the text <CODE>barfoofoobarfoo</CODE>. The +The first pattern matches the words <SAMP>`foo'</SAMP> or <SAMP>`bar'</SAMP> any number of +times, e.g., it matches the text <SAMP>`barfoofoobarfoo'</SAMP>. The second pattern matches a single instance of <CODE>foo</CODE> or a single instance of -<CODE>ba</CODE> followed by one or more <SAMP>`r'</SAMP>s, e.g., it matches the text <CODE>barrrr</CODE> . +<CODE>bar</CODE> followed by one or more <SAMP>`r'</SAMP>s, e.g., it matches the text <CODE>barrrr</CODE> . <LI> -A <SAMP>`.'</SAMP> inside []'s just means a literal<SAMP>`.'</SAMP> (period), +A <SAMP>`.'</SAMP> inside <SAMP>`[]'</SAMP>'s just means a literal<SAMP>`.'</SAMP> (period), and NOT "any character except newline". <LI> -Remember that <SAMP>`.'</SAMP> matches any character EXCEPT <SAMP>`\n'</SAMP> (and EOF). +Remember that <SAMP>`.'</SAMP> matches any character EXCEPT <SAMP>`\n'</SAMP> (and <SAMP>`EOF'</SAMP>). If you really want to match ANY character, including newlines, then use <CODE>(.|\n)</CODE> ---- Beware that the regex <CODE>(.|\n)+</CODE> will match your entire input! +Beware that the regex <CODE>(.|\n)+</CODE> will match your entire input! <LI> -Finally, if you want to match a literal <SAMP>`.'</SAMP> (a period), then use [.] or "." +Finally, if you want to match a literal <SAMP>`.'</SAMP> (a period), then use <SAMP>`[.]'</SAMP> or <SAMP>`"."'</SAMP> </UL> -<H2><A NAME="SEC60" HREF="flex_toc.html#TOC60">Can I get the flex manual in another format?</A></H2> +<H2><A NAME="SEC72" HREF="flex_toc.html#TOC72">Can I get the flex manual in another format?</A></H2> <P> -Can I get the flex manual in another format? +The <CODE>flex</CODE> source distribution includes a texinfo manual. You are +free to convert that texinfo into whatever format you desire. The +<CODE>texinfo</CODE> package includes tools for conversion to a number of formats. -<P> -As of flex 2.5, the manual is distributed in texinfo format. -You can use the "texi2*" tools to convert the manual to any format -you desire (e.g., <SAMP>`texi2html'</SAMP>). - - -<H2><A NAME="SEC61" HREF="flex_toc.html#TOC61">Does there exist a "faster" NDFA->DFA algorithm?</A></H2> - -<P> -Does there exist a "faster" NDFA->DFA algorithm? Most standard texts (e.g., -Aho), imply that NDFA->DFA can take exponential time, since there are -exponential number of potential states in NDFA. - +<H2><A NAME="SEC73" HREF="flex_toc.html#TOC73">Does there exist a "faster" NDFA->DFA algorithm?</A></H2> <P> There's no way around the potential exponential running time - it @@ -5625,14 +6261,10 @@ -<H2><A NAME="SEC62" HREF="flex_toc.html#TOC62">How does flex compile the DFA so quickly?</A></H2> +<H2><A NAME="SEC74" HREF="flex_toc.html#TOC74">How does flex compile the DFA so quickly?</A></H2> <P> -How does flex compile the DFA so quickly? - - -<P> -There are two big speed wins that flex uses: +There are two big speed wins that <CODE>flex</CODE> uses: @@ -5654,16 +6286,12 @@ -<H2><A NAME="SEC63" HREF="flex_toc.html#TOC63">How can I use more than 8192 rules?</A></H2> - -<P> -How can I use more than 8192 rules? - +<H2><A NAME="SEC75" HREF="flex_toc.html#TOC75">How can I use more than 8192 rules?</A></H2> <P> -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: +<CODE>Flex</CODE> 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 <CODE>flex</CODE> +with the following changes in <TT>`flexdef.h'</TT>: @@ -5682,150 +6310,117 @@ is the best way to solve your problem. - - -<H2><A NAME="SEC64" HREF="flex_toc.html#TOC64">How do I abandon a file in the middle of a scan and switch to a new file?</A></H2> - -<P> -How do I abandon a file in the middle of a scan and switch to a new file? - - -<P> -Just all 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. - - - - -<H2><A NAME="SEC65" HREF="flex_toc.html#TOC65">How do I execute code only during initialization (only before the first scan)?</A></H2> - <P> -How do I execute code only during initialization (only before the first scan)? +The following may also be relevant: <P> -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: +With luck, you should be able to increase the definitions in flexdef.h for: <PRE> @verbatim -%% - /* Must be indented! */ - static int did_init = 0; - - if ( ! did_init ){ - do_my_init(); - did_init = 1; - } +#define JAMSTATE -32766 /* marks a reference to the state that always jams */ +#define MAXIMUM_MNS 31999 +#define BAD_SUBSCRIPT -32767 </PRE> - - -<H2><A NAME="SEC66" HREF="flex_toc.html#TOC66">How do I execute code at termination?</A></H2> - <P> -How do I execute code at termination (i.e., only after the last scan?) - - -<P> -You can specifiy an action for the <<EOF>> rule. +recompile everything, and it'll all work. Flex only has these 16-bit-like +values built into it because a long time ago it was developed on a machine +with 16-bit ints. I've given this advice to others in the past but haven't +heard back from them whether it worked okay or not... -<H2><A NAME="SEC67" HREF="flex_toc.html#TOC67">Where else can I find help?</A></H2> -<P> -Where else can I find help? +<H2><A NAME="SEC76" HREF="flex_toc.html#TOC76">How do I abandon a file in the middle of a scan and switch to a new file?</A></H2> <P> -The <CODE>help-flex</CODE> email list is served by GNU. See http://www.gnu.org/ for -details how to subscribe or search the archives. +Just call <CODE>yyrestart(newfile)</CODE>. Be sure to reset the start state if you want a +"fresh start, since <CODE>yyrestart</CODE> does NOT reset the start state back to <CODE>INITIAL</CODE>. -<H2><A NAME="SEC68" HREF="flex_toc.html#TOC68">Can I include comments in the "rules" section of the file file?</A></H2> +<H2><A NAME="SEC77" HREF="flex_toc.html#TOC77">How do I execute code only during initialization (only before the first scan)?</A></H2> <P> -Can I include comments in the "rules" section of the file file? - +You can specify an initial action by defining the macro <CODE>YY_USER_INIT</CODE> (though +note that <CODE>yyout</CODE> may not be available at the time this macro is executed). Or you +can add to the beginning of your rules section: -<P> -Yes, just about anywhere you want to. See the manual for the specific syntax. +<PRE> +@verbatim +%% +/* Must be indented! */ +static int did_init = 0; +if ( ! did_init ){ +do_my_init(); +did_init = 1; +} +</PRE> -<H2><A NAME="SEC69" HREF="flex_toc.html#TOC69">I get an error about undefined yywrap().</A></H2> -<P> -I get an error about undefined yywrap(). +<H2><A NAME="SEC78" HREF="flex_toc.html#TOC78">How do I execute code at termination?</A></H2> <P> -You must supply a yywrap() function of your own, or link to libfl.a -(which provides one), or use +You can specify an action for the <CODE><<EOF>></CODE> rule. -<P> - %option noyywrap -<P> -in your source to say you don't want a yywrap() function. -See the manual page for more details concerning yywrap(). - +<H2><A NAME="SEC79" HREF="flex_toc.html#TOC79">Where else can I find help?</A></H2> +<P> +The <CODE>help-flex</CODE> email list is served by GNU. See <A HREF="http://www.gnu.org/">http://www.gnu.org/</A> for +details on how to subscribe or search the archives. -<H2><A NAME="SEC70" HREF="flex_toc.html#TOC70">How can I change the matching pattern at run time?</A></H2> -<P> -How can I change the matching pattern at run time? +<H2><A NAME="SEC80" HREF="flex_toc.html#TOC80">Can I include comments in the "rules" section of the file?</A></H2> <P> -You can't, it's compiled into a static table when flex builds the scanner. - - +Yes, just about anywhere you want to. See the manual for the specific syntax. -<H2><A NAME="SEC71" HREF="flex_toc.html#TOC71">Is there a way to increase the rules (NFA states to a bigger number?)</A></H2> -<P> -Is there a way to increase the rules (NFA states to a bigger number?) +<H2><A NAME="SEC81" HREF="flex_toc.html#TOC81">I get an error about undefined yywrap().</A></H2> <P> -With luck, you should be able to increase the definitions in flexdef.h for: +You must supply a <CODE>yywrap()</CODE> function of your own, or link to <TT>`libfl.a'</TT> +(which provides one), or use <PRE> @verbatim -#define JAMSTATE -32766 /* marks a reference to the state that always jams */ -#define MAXIMUM_MNS 31999 -#define BAD_SUBSCRIPT -32767 +%option noyywrap </PRE> <P> -recompile everything, and it'll all work. Flex only has these 16-bit-like -values built into it because a long time ago it was developed on a machine -with 16-bit ints. I've given this advice to others in the past but haven't -heard back from them whether it worked okay or not... +in your source to say you don't want a <CODE>yywrap()</CODE> function. -<H2><A NAME="SEC72" HREF="flex_toc.html#TOC72">How can I expand macros in the input?</A></H2> +<H2><A NAME="SEC82" HREF="flex_toc.html#TOC82">How can I change the matching pattern at run time?</A></H2> <P> -How can I expand macros in the input? +You can't, it's compiled into a static table when flex builds the scanner. + + +<H2><A NAME="SEC83" HREF="flex_toc.html#TOC83">How can I expand macros in the input?</A></H2> + <P> The best way to approach this problem is at a higher level, e.g., in the parser. @@ -5839,24 +6434,24 @@ @verbatim %% macro/[a-z]+ { - /* Saw the macro "macro" followed by extra stuff. */ - main_buffer = YY_CURRENT_BUFFER; - expansion_buffer = yy_scan_string(expand(yytext)); - yy_switch_to_buffer(expansion_buffer); - } +/* Saw the macro "macro" followed by extra stuff. */ +main_buffer = YY_CURRENT_BUFFER; +expansion_buffer = yy_scan_string(expand(yytext)); +yy_switch_to_buffer(expansion_buffer); +} <<EOF>> { - if ( expansion_buffer ) - { - // We were doing an expansion, return to where - // we were. - yy_switch_to_buffer(main_buffer); - yy_delete_buffer(expansion_buffer); - expansion_buffer = 0; - } - else - yyterminate(); - } +if ( expansion_buffer ) +{ +// We were doing an expansion, return to where +// we were. +yy_switch_to_buffer(main_buffer); +yy_delete_buffer(expansion_buffer); +expansion_buffer = 0; +} +else +yyterminate(); +} </PRE> <P> @@ -5866,11 +6461,7 @@ -<H2><A NAME="SEC73" HREF="flex_toc.html#TOC73">How can I build a two-pass scanner?</A></H2> - -<P> -How can I build a two-pass scanner? - +<H2><A NAME="SEC84" HREF="flex_toc.html#TOC84">How can I build a two-pass scanner?</A></H2> <P> One way to do it is to filter the first pass to a temporary file, @@ -5890,16 +6481,12 @@ -<H2><A NAME="SEC74" HREF="flex_toc.html#TOC74">How do I match any string not matched in the preceding rules?</A></H2> - -<P> -How do I match any string not matched in the preceding rules? - +<H2><A NAME="SEC85" HREF="flex_toc.html#TOC85">How do I match any string not matched in the preceding rules?</A></H2> <P> 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., +first rule listed in the <CODE>flex</CODE> input wins. e.g., @@ -5914,47 +6501,35 @@ <P> Note that the rule <CODE>[a-zA-Z_]+</CODE> 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 scanner as the +<CODE>flex</CODE> scanner will pick the first rule listed in your scanner as the one to match. -<H2><A NAME="SEC75" HREF="flex_toc.html#TOC75">I am trying to port code from AT&T lex that uses yysptr and yysbuf.</A></H2> - -<P> -I am trying to port code from AT&T lex that uses yysptr and yysbuf. - +<H2><A NAME="SEC86" HREF="flex_toc.html#TOC86">I am trying to port code from AT&T lex that uses yysptr and yysbuf.</A></H2> <P> 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() +imagine they're being manipulated in user versions of the <CODE>input()</CODE> and <CODE>unput()</CODE> 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 (see the flex man page). You shouldn't need to (and must not) replace -flex's unput() function. +what they're doing, and then replace <CODE>input()</CODE> with an appropriate definition of +<CODE>YY_INPUT</CODE>. You shouldn't need to (and must not) replace +<CODE>flex</CODE>'s <CODE>unput()</CODE> function. -<H2><A NAME="SEC76" HREF="flex_toc.html#TOC76">Is there a way to make flex treat NULL like a regular character?</A></H2> +<H2><A NAME="SEC87" HREF="flex_toc.html#TOC87">Is there a way to make flex treat NULL like a regular character?</A></H2> <P> -Is there a way to make flex treat NULL like a regular character? +Yes, <SAMP>`\0'</SAMP> and <SAMP>`\x00'</SAMP> should both do the trick. Perhaps you have an ancient +version of <CODE>flex</CODE>. The latest release is version 2.5.23. -<P> -Yes, \0 and \x00 should both do the trick. Perhaps you have an ancient -version of flex. The latest release is version 2.5.8. - - -<H2><A NAME="SEC77" HREF="flex_toc.html#TOC77">Whenever flex can not match the input it says "flex scanner jammed".</A></H2> - -<P> -Whenever flex can not match the input it says "flex scanner jammed". - +<H2><A NAME="SEC88" HREF="flex_toc.html#TOC88">Whenever flex can not match the input it says "flex scanner jammed".</A></H2> <P> You need to add a rule that matches the otherwise-unmatched text. @@ -5972,16 +6547,12 @@ </PRE> <P> -See %option default for more information. +See <CODE>%option default</CODE> for more information. -<H2><A NAME="SEC78" HREF="flex_toc.html#TOC78">Why doesn't flex have non-greedy operators like perl does?</A></H2> - -<P> -Why doesn't flex have non-greedy operators like perl does? - +<H2><A NAME="SEC89" HREF="flex_toc.html#TOC89">Why doesn't flex have non-greedy operators like perl does?</A></H2> <P> A DFA can do a non-greedy match by stopping @@ -5996,14 +6567,14 @@ sign that you're trying to make the scanner do some parsing. That's generally the wrong approach, since it lacks the power to do a decent job. Better is to either introduce a separate parser, or to split the scanner -into multiple scanners using (exclusive) start conditions. +into multiple scanners using (exclusive) start conditions. <P> 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 ... +a separate start state once you've seen the <SAMP>`BEGIN'</SAMP>. In that state, you +might then have a regex that will match <SAMP>`END'</SAMP> (to kick you out of the +state), and perhaps <SAMP>`(.|\n)'</SAMP> to get a single character within the chunk ... <P> @@ -6012,14 +6583,2137 @@ -<H1><A NAME="SEC79" HREF="flex_toc.html#TOC79">Appendices</A></H1> +<H2><A NAME="SEC90" HREF="flex_toc.html#TOC90">Memory leak - 16386 bytes allocated by malloc.</A></H2> +<P> +@anchor{faq-memory-leak} +<P> +UPDATED 2002-07-10: As of <CODE>flex</CODE> version 2.5.9, this leak means that you did not +call <CODE>yylex_destroy()</CODE>. If you are using an earlier version of <CODE>flex</CODE>, then read +on. -<H2><A NAME="SEC80" HREF="flex_toc.html#TOC80">Makefiles and Flex</A></H2> <P> -<A NAME="IDX297"></A> +The leak is about 16426 bytes. That is, (8192 * 2 + 2) for the read-buffer, and +about 40 for <CODE>struct yy_buffer_state</CODE> (depending upon alignment). The leak is in +the non-reentrant C scanner only (NOT in the reentrant scanner, NOT in the C++ +scanner). Since <CODE>flex</CODE> doesn't know when you are done, the buffer is never freed. + + +<P> +However, the leak won't multiply since the buffer is reused no matter how many +times you call <CODE>yylex()</CODE>. + + +<P> +If you want to reclaim the memory when you are completely done scanning, then +you might try this: + + + +<PRE> +@verbatim +/* For non-reentrant C scanner only. */ +yy_delete_buffer(yy_current_buffer); +yy_init = 1; +</PRE> + +<P> +Note: <CODE>yy_init</CODE> is an "internal variable", and hasn't been tested in this +situation. It is possible that some other globals may need resetting as well. + + + + +<H2><A NAME="SEC91" HREF="flex_toc.html#TOC91">How do I track the byte offset for lseek()?</A></H2> + + +<PRE> +@verbatim +> We thought that it would be possible to have this number through the +> evaluation of the following expression: +> +> seek_position = (no_buffers)*YY_READ_BUF_SIZE + yy_c_buf_p - yy_current_buffer->yy_ch_buf +</PRE> + +<P> +While this is the right idea, it has two problems. The first is that +it's possible that <CODE>flex</CODE> will request less than <CODE>YY_READ_BUF_SIZE</CODE> during +an invocation of <CODE>YY_INPUT</CODE> (or that your input source will return less +even though <CODE>YY_READ_BUF_SIZE</CODE> bytes were requested). The second problem +is that when refilling its internal buffer, <CODE>flex</CODE> keeps some characters +from the previous buffer (because usually it's in the middle of a match, +and needs those characters to construct <CODE>yytext</CODE> for the match once it's +done). Because of this, <CODE>yy_c_buf_p - yy_current_buffer->yy_ch_buf</CODE> won't +be exactly the number of characters already read from the current buffer. + + +<P> +An alternative solution is to count the number of characters you've matched +since starting to scan. This can be done by using <CODE>YY_USER_ACTION</CODE>. For +example, + + + +<PRE> +@verbatim +#define YY_USER_ACTION num_chars += yyleng; +</PRE> + +<P> +(You need to be careful to update your bookkeeping if you use <CODE>yymore(</CODE>), +<CODE>yyless()</CODE>, <CODE>unput()</CODE>, or <CODE>input()</CODE>.) + + + + +<H2><A NAME="SEC92" HREF="flex_toc.html#TOC92">How do I use my own I/O classes in a C++ scanner?</A></H2> + +<P> +When the flex C++ scanning class rewrite finally happens, then this sort of thing should become much easier. + + +<P> +<A NAME="IDX457"></A> +<A NAME="IDX458"></A> +<A NAME="IDX459"></A> +<A NAME="IDX460"></A> +<A NAME="IDX461"></A> +<A NAME="IDX462"></A> +You can do this by passing the various functions (such as <CODE>LexerInput()</CODE> +and <CODE>LexerOutput()</CODE>) nil <CODE>iostream*</CODE>'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 <CODE>LexerInput()</CODE> and <CODE>LexerOutput</CODE>, which then do whatever +is necessary with them. + + + + +<H2><A NAME="SEC93" HREF="flex_toc.html#TOC93">How do I skip as many chars as possible?</A></H2> + +<P> +How do I skip as many chars as possible -- without interfering with the other +patterns? + + +<P> +In the example below, we want to skip over characters until we see the phrase +"endskip". The following will <EM>NOT</EM> work correctly (do you see why not?) + + + +<PRE> +@verbatim +/* INCORRECT SCANNER */ +%x SKIP +%% +<INITIAL>startskip BEGIN(SKIP); +... +<SKIP>"endskip" BEGIN(INITIAL); +<SKIP>.* ; +</PRE> + +<P> +The problem is that the pattern .* will eat up the word "endskip." +The simplest (but slow) fix is: + + + +<PRE> +@verbatim +<SKIP>"endskip" BEGIN(INITIAL); +<SKIP>. ; +</PRE> + +<P> +The fix involves making the second rule match more, without +making it match "endskip" plus something else. So for example: + + + +<PRE> +@verbatim +<SKIP>"endskip" BEGIN(INITIAL); +<SKIP>[^e]+ ; +<SKIP>. ;/* so you eat up e's, too */ +</PRE> + + + +<H2><A NAME="SEC94" HREF="flex_toc.html#TOC94">unnamed-faq-33</A></H2> + +<PRE> +@verbatim +QUESTION: +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 :-). +</PRE> + + + +<H2><A NAME="SEC95" HREF="flex_toc.html#TOC95">unnamed-faq-42</A></H2> + +<PRE> +@verbatim +To: Adoram Rogel <adoram@orna.hybridge.com> +Subject: Re: Flex 2.5.2 performance questions +In-reply-to: Your message of Wed, 18 Sep 96 11:12:17 EDT. +Date: Wed, 18 Sep 96 10:51:02 PDT +From: Vern Paxson <vern> + +[Note, the most recent flex release is 2.5.4, which you can get from +ftp.ee.lbl.gov. It has bug fixes over 2.5.2 and 2.5.3.] + +> 1. Using the pattern +> ([Ff](oot)?)?[Nn](ote)?(\.)? +> instead of +> (((F|f)oot(N|n)ote)|((N|n)ote)|((N|n)\.)|((F|f)(N|n)(\.))) +> (in a very complicated flex program) caused the program to slow from +> 300K+/min to 100K/min (no other changes were done). + +These two are not equivalent. For example, the first can match "footnote." +but the second can only match "footnote". This is almost certainly the +cause in the discrepancy - the slower scanner run is matching more tokens, +and/or having to do more backing up. + +> 2. Which of these two are better: [Ff]oot or (F|f)oot ? + +From a performance point of view, they're equivalent (modulo presumably +minor effects such as memory cache hit rates; and the presence of trailing +context, see below). From a space point of view, the first is slightly +preferable. + +> 3. I have a pattern that look like this: +> pats {p1}|{p2}|{p3}|...|{p50} (50 patterns ORd) +> +> running yet another complicated program that includes the following rule: +> <snext>{and}/{no4}{bb}{pats} +> +> gets me to "too complicated - over 32,000 states"... + +I can't tell from this example whether the trailing context is variable-length +or fixed-length (it could be the latter if {and} is fixed-length). If it's +variable length, which flex -p will tell you, then this reflects a basic +performance problem, and if you can eliminate it by restructuring your +scanner, you will see significant improvement. + +> so I divided {pats} to {pats1}, {pats2},..., {pats5} each consists of about +> 10 patterns and changed the rule to be 5 rules. +> This did compile, but what is the rule of thumb here ? + +The rule is to avoid trailing context other than fixed-length, in which for +a/b, either the 'a' pattern or the 'b' pattern have a fixed length. Use +of the '|' operator automatically makes the pattern variable length, so in +this case '[Ff]oot' is preferred to '(F|f)oot'. + +> 4. I changed a rule that looked like this: +> <snext8>{and}{bb}/{ROMAN}[^A-Za-z] { BEGIN... +> +> to the next 2 rules: +> <snext8>{and}{bb}/{ROMAN}[A-Za-z] { ECHO;} +> <snext8>{and}{bb}/{ROMAN} { BEGIN... +> +> Again, I understand the using [^...] will cause a great performance loss + +Actually, it doesn't cause any sort of performance loss. It's a surprising +fact about regular expressions that they always match in linear time +regardless of how complex they are. + +> but are there any specific rules about it ? + +See the "Performance Considerations" section of the man page, and also +the example in MISC/fastwc/. + + Vern +</PRE> + + + +<H2><A NAME="SEC96" HREF="flex_toc.html#TOC96">unnamed-faq-43</A></H2> + +<PRE> +@verbatim +To: Adoram Rogel <adoram@hybridge.com> +Subject: Re: Flex 2.5.2 performance questions +In-reply-to: Your message of Thu, 19 Sep 96 10:16:04 EDT. +Date: Thu, 19 Sep 96 09:58:00 PDT +From: Vern Paxson <vern> + +> a lot about the backing up problem. +> I believe that there lies my biggest problem, and I'll try to improve +> it. + +Since you have variable trailing context, this is a bigger performance +problem. Fixing it is usually easier than fixing backing up, which in a +complicated scanner (yours seems to fit the bill) can be extremely +difficult to do correctly. + +You also don't mention what flags you are using for your scanner. +-f makes a large speed difference, and -Cfe buys you nearly as much +speed but the resulting scanner is considerably smaller. + +> I have an | operator in {and} and in {pats} so both of them are variable +> length. + +-p should have reported this. + +> Is changing one of them to fixed-length is enough ? + +Yes. + +> Is it possible to change the 32,000 states limit ? + +Yes. I've appended instructions on how. Before you make this change, +though, you should think about whether there are ways to fundamentally +simplify your scanner - those are certainly preferable! + + Vern + +To increase the 32K limit (on a machine with 32 bit integers), you increase +the magnitude of the following in flexdef.h: + +#define JAMSTATE -32766 /* marks a reference to the state that always jams */ +#define MAXIMUM_MNS 31999 +#define BAD_SUBSCRIPT -32767 +#define MAX_SHORT 32700 + +Adding a 0 or two after each should do the trick. +</PRE> + + + +<H2><A NAME="SEC97" HREF="flex_toc.html#TOC97">unnamed-faq-44</A></H2> + +<PRE> +@verbatim +To: Heeman_Lee@hp.com +Subject: Re: flex - multi-byte support? +In-reply-to: Your message of Thu, 03 Oct 1996 17:24:04 PDT. +Date: Fri, 04 Oct 1996 11:42:18 PDT +From: Vern Paxson <vern> + +> I assume as long as my *.l file defines the +> range of expected character code values (in octal format), flex will +> scan the file and read multi-byte characters correctly. But I have no +> confidence in this assumption. + +Your lack of confidence is justified - this won't work. + +Flex has in it a widespread assumption that the input is processed +one byte at a time. Fixing this is on the to-do list, but is involved, +so it won't happen any time soon. In the interim, the best I can suggest +(unless you want to try fixing it yourself) is to write your rules in +terms of pairs of bytes, using definitions in the first section: + + X \xfe\xc2 + ... + %% + foo{X}bar found_foo_fe_c2_bar(); + +etc. Definitely a pain - sorry about that. + +By the way, the email address you used for me is ancient, indicating you +have a very old version of flex. You can get the most recent, 2.5.4, from +ftp.ee.lbl.gov. + + Vern +</PRE> + + + +<H2><A NAME="SEC98" HREF="flex_toc.html#TOC98">unnamed-faq-45</A></H2> + +<PRE> +@verbatim +To: moleary@primus.com +Subject: Re: Flex / Unicode compatibility question +In-reply-to: Your message of Tue, 22 Oct 1996 10:15:42 PDT. +Date: Tue, 22 Oct 1996 11:06:13 PDT +From: Vern Paxson <vern> + +Unfortunately flex at the moment has a widespread assumption within it +that characters are processed 8 bits at a time. I don't see any easy +fix for this (other than writing your rules in terms of double characters - +a pain). I also don't know of a wider lex, though you might try surfing +the Plan 9 stuff because I know it's a Unicode system, and also the PCCT +toolkit (try searching say Alta Vista for "Purdue Compiler Construction +Toolkit"). + +Fixing flex to handle wider characters is on the long-term to-do list. +But since flex is a strictly spare-time project these days, this probably +won't happen for quite a while, unless someone else does it first. + + Vern +</PRE> + + + +<H2><A NAME="SEC99" HREF="flex_toc.html#TOC99">unnamed-faq-46</A></H2> + +<PRE> +@verbatim +To: Johan Linde <jl@theophys.kth.se> +Subject: Re: translation of flex +In-reply-to: Your message of Sun, 10 Nov 1996 09:16:36 PST. +Date: Mon, 11 Nov 1996 10:33:50 PST +From: Vern Paxson <vern> + +> I'm working for the Swedish team translating GNU program, and I'm currently +> working with flex. I have a few questions about some of the messages which +> I hope you can answer. + +All of the things you're wondering about, by the way, concerning flex +internals - probably the only person who understands what they mean in +English is me! So I wouldn't worry too much about getting them right. +That said ... + +> #: main.c:545 +> msgid " %d protos created\n" +> +> Does proto mean prototype? + +Yes - prototypes of state compression tables. + +> #: main.c:539 +> msgid " %d/%d (peak %d) template nxt-chk entries created\n" +> +> Here I'm mainly puzzled by 'nxt-chk'. I guess it means 'next-check'. (?) +> However, 'template next-check entries' doesn't make much sense to me. To be +> able to find a good translation I need to know a little bit more about it. + +There is a scheme in the Aho/Sethi/Ullman compiler book for compressing +scanner tables. It involves creating two pairs of tables. The first has +"base" and "default" entries, the second has "next" and "check" entries. +The "base" entry is indexed by the current state and yields an index into +the next/check table. The "default" entry gives what to do if the state +transition isn't found in next/check. The "next" entry gives the next +state to enter, but only if the "check" entry verifies that this entry is +correct for the current state. Flex creates templates of series of +next/check entries and then encodes differences from these templates as a +way to compress the tables. + +> #: main.c:533 +> msgid " %d/%d base-def entries created\n" +> +> The same problem here for 'base-def'. + +See above. + + Vern +</PRE> + + + +<H2><A NAME="SEC100" HREF="flex_toc.html#TOC100">unnamed-faq-47</A></H2> + +<PRE> +@verbatim +To: Xinying Li <xli@npac.syr.edu> +Subject: Re: FLEX ? +In-reply-to: Your message of Wed, 13 Nov 1996 17:28:38 PST. +Date: Wed, 13 Nov 1996 19:51:54 PST +From: Vern Paxson <vern> + +> "unput()" them to input flow, question occurs. If I do this after I scan +> a carriage, the variable "yy_current_buffer->yy_at_bol" is changed. That +> means the carriage flag has gone. + +You can control this by calling yy_set_bol(). It's described in the manual. + +> And if in pre-reading it goes to the end of file, is anything done +> to control the end of curren buffer and end of file? + +No, there's no way to put back an end-of-file. + +> By the way I am using flex 2.5.2 and using the "-l". + +The latest release is 2.5.4, by the way. It fixes some bugs in 2.5.2 and +2.5.3. You can get it from ftp.ee.lbl.gov. + + Vern +</PRE> + + + +<H2><A NAME="SEC101" HREF="flex_toc.html#TOC101">unnamed-faq-48</A></H2> + +<PRE> +@verbatim +To: Alain.ISSARD@st.com +Subject: Re: Start condition with FLEX +In-reply-to: Your message of Mon, 18 Nov 1996 09:45:02 PST. +Date: Mon, 18 Nov 1996 10:41:34 PST +From: Vern Paxson <vern> + +> I am not able to use the start condition scope and to use the | (OR) with +> rules having start conditions. + +The problem is that if you use '|' as a regular expression operator, for +example "a|b" meaning "match either 'a' or 'b'", then it must *not* have +any blanks around it. If you instead want the special '|' *action* (which +from your scanner appears to be the case), which is a way of giving two +different rules the same action: + + foo | + bar matched_foo_or_bar(); + +then '|' *must* be separated from the first rule by whitespace and *must* +be followed by a new line. You *cannot* write it as: + + foo | bar matched_foo_or_bar(); + +even though you might think you could because yacc supports this syntax. +The reason for this unfortunately incompatibility is historical, but it's +unlikely to be changed. + +Your problems with start condition scope are simply due to syntax errors +from your use of '|' later confusing flex. + +Let me know if you still have problems. + + Vern +</PRE> + + + +<H2><A NAME="SEC102" HREF="flex_toc.html#TOC102">unnamed-faq-49</A></H2> + +<PRE> +@verbatim +To: Gregory Margo <gmargo@newton.vip.best.com> +Subject: Re: flex-2.5.3 bug report +In-reply-to: Your message of Sat, 23 Nov 1996 16:50:09 PST. +Date: Sat, 23 Nov 1996 17:07:32 PST +From: Vern Paxson <vern> + +> Enclosed is a lex file that "real" lex will process, but I cannot get +> flex to process it. Could you try it and maybe point me in the right direction? + +Your problem is that some of the definitions in the scanner use the '/' +trailing context operator, and have it enclosed in ()'s. Flex does not +allow this operator to be enclosed in ()'s because doing so allows undefined +regular expressions such as "(a/b)+". So the solution is to remove the +parentheses. Note that you must also be building the scanner with the -l +option for AT&T lex compatibility. Without this option, flex automatically +encloses the definitions in parentheses. + + Vern +</PRE> + + + +<H2><A NAME="SEC103" HREF="flex_toc.html#TOC103">unnamed-faq-50</A></H2> + +<PRE> +@verbatim +To: Thomas Hadig <hadig@toots.physik.rwth-aachen.de> +Subject: Re: Flex Bug ? +In-reply-to: Your message of Tue, 26 Nov 1996 14:35:01 PST. +Date: Tue, 26 Nov 1996 11:15:05 PST +From: Vern Paxson <vern> + +> In my lexer code, i have the line : +> ^\*.* { } +> +> Thus all lines starting with an astrix (*) are comment lines. +> This does not work ! + +I can't get this problem to reproduce - it works fine for me. Note +though that if what you have is slightly different: + + COMMENT ^\*.* + %% + {COMMENT} { } + +then it won't work, because flex pushes back macro definitions enclosed +in ()'s, so the rule becomes + + (^\*.*) { } + +and now that the '^' operator is not at the immediate beginning of the +line, it's interpreted as just a regular character. You can avoid this +behavior by using the "-l" lex-compatibility flag, or "%option lex-compat". + + Vern +</PRE> + + + +<H2><A NAME="SEC104" HREF="flex_toc.html#TOC104">unnamed-faq-51</A></H2> + +<PRE> +@verbatim +To: Adoram Rogel <adoram@hybridge.com> +Subject: Re: Flex 2.5.4 BOF ??? +In-reply-to: Your message of Tue, 26 Nov 1996 16:10:41 PST. +Date: Wed, 27 Nov 1996 10:56:25 PST +From: Vern Paxson <vern> + +> Organization(s)?/[a-z] +> +> This matched "Organizations" (looking in debug mode, the trailing s +> was matched with trailing context instead of the optional (s) in the +> end of the word. + +That should only happen with lex. Flex can properly match this pattern. +(That might be what you're saying, I'm just not sure.) + +> Is there a way to avoid this dangerous trailing context problem ? + +Unfortunately, there's no easy way. On the other hand, I don't see why +it should be a problem. Lex's matching is clearly wrong, and I'd hope +that usually the intent remains the same as expressed with the pattern, +so flex's matching will be correct. + + Vern +</PRE> + + + +<H2><A NAME="SEC105" HREF="flex_toc.html#TOC105">unnamed-faq-52</A></H2> + +<PRE> +@verbatim +To: Cameron MacKinnon <mackin@interlog.com> +Subject: Re: Flex documentation bug +In-reply-to: Your message of Mon, 02 Dec 1996 00:07:08 PST. +Date: Sun, 01 Dec 1996 22:29:39 PST +From: Vern Paxson <vern> + +> I'm not sure how or where to submit bug reports (documentation or +> otherwise) for the GNU project stuff ... + +Well, strictly speaking flex isn't part of the GNU project. They just +distribute it because no one's written a decent GPL'd lex replacement. +So you should send bugs directly to me. Those sent to the GNU folks +sometimes find there way to me, but some may drop between the cracks. + +> In GNU Info, under the section 'Start Conditions', and also in the man +> page (mine's dated April '95) is a nice little snippet showing how to +> parse C quoted strings into a buffer, defined to be MAX_STR_CONST in +> size. Unfortunately, no overflow checking is ever done ... + +This is already mentioned in the manual: + +Finally, here's an example of how to match C-style quoted +strings using exclusive start conditions, including expanded +escape sequences (but not including checking for a string +that's too long): + +The reason for not doing the overflow checking is that it will needlessly +clutter up an example whose main purpose is just to demonstrate how to +use flex. + +The latest release is 2.5.4, by the way, available from ftp.ee.lbl.gov. + + Vern +</PRE> + + + +<H2><A NAME="SEC106" HREF="flex_toc.html#TOC106">unnamed-faq-53</A></H2> + +<PRE> +@verbatim +To: tsv@cs.UManitoba.CA +Subject: Re: Flex (reg).. +In-reply-to: Your message of Thu, 06 Mar 1997 23:50:16 PST. +Date: Thu, 06 Mar 1997 15:54:19 PST +From: Vern Paxson <vern> + +> [:alpha:] ([:alnum:] | \\_)* + +If your rule really has embedded blanks as shown above, then it won't +work, as the first blank delimits the rule from the action. (It wouldn't +even compile ...) You need instead: + +[:alpha:]([:alnum:]|\\_)* + +and that should work fine - there's no restriction on what can go inside +of ()'s except for the trailing context operator, '/'. + + Vern +</PRE> + + + +<H2><A NAME="SEC107" HREF="flex_toc.html#TOC107">unnamed-faq-54</A></H2> + +<PRE> +@verbatim +To: "Mike Stolnicki" <mstolnic@ford.com> +Subject: Re: FLEX help +In-reply-to: Your message of Fri, 30 May 1997 13:33:27 PDT. +Date: Fri, 30 May 1997 10:46:35 PDT +From: Vern Paxson <vern> + +> We'd like to add "if-then-else", "while", and "for" statements to our +> language ... +> We've investigated many possible solutions. The one solution that seems +> the most reasonable involves knowing the position of a TOKEN in yyin. + +I strongly advise you to instead build a parse tree (abstract syntax tree) +and loop over that instead. You'll find this has major benefits in keeping +your interpreter simple and extensible. + +That said, the functionality you mention for get_position and set_position +have been on the to-do list for a while. As flex is a purely spare-time +project for me, no guarantees when this will be added (in particular, it +for sure won't be for many months to come). + + Vern +</PRE> + + + +<H2><A NAME="SEC108" HREF="flex_toc.html#TOC108">unnamed-faq-55</A></H2> + +<PRE> +@verbatim +To: Colin Paul Adams <colin@colina.demon.co.uk> +Subject: Re: Flex C++ classes and Bison +In-reply-to: Your message of 09 Aug 1997 17:11:41 PDT. +Date: Fri, 15 Aug 1997 10:48:19 PDT +From: Vern Paxson <vern> + +> #define YY_DECL int yylex (YYSTYPE *lvalp, struct parser_control +> *parm) +> +> I have been trying to get this to work as a C++ scanner, but it does +> not appear to be possible (warning that it matches no declarations in +> yyFlexLexer, or something like that). +> +> Is this supposed to be possible, or is it being worked on (I DID +> notice the comment that scanner classes are still experimental, so I'm +> not too hopeful)? + +What you need to do is derive a subclass from yyFlexLexer that provides +the above yylex() method, squirrels away lvalp and parm into member +variables, and then invokes yyFlexLexer::yylex() to do the regular scanning. + + Vern +</PRE> + + + +<H2><A NAME="SEC109" HREF="flex_toc.html#TOC109">unnamed-faq-56</A></H2> + +<PRE> +@verbatim +To: Mikael.Latvala@lmf.ericsson.se +Subject: Re: Possible mistake in Flex v2.5 document +In-reply-to: Your message of Fri, 05 Sep 1997 16:07:24 PDT. +Date: Fri, 05 Sep 1997 10:01:54 PDT +From: Vern Paxson <vern> + +> In that example you show how to count comment lines when using +> C style /* ... */ comments. My question is, shouldn't you take into +> account a scenario where end of a comment marker occurs inside +> character or string literals? + +The scanner certainly needs to also scan character and string literals. +However it does that (there's an example in the man page for strings), the +lexer will recognize the beginning of the literal before it runs across the +embedded "/*". Consequently, it will finish scanning the literal before it +even considers the possibility of matching "/*". + +Example: + + '([^']*|{ESCAPE_SEQUENCE})' + +will match all the text between the ''s (inclusive). So the lexer +considers this as a token beginning at the first ', and doesn't even +attempt to match other tokens inside it. + +I thinnk this subtlety is not worth putting in the manual, as I suspect +it would confuse more people than it would enlighten. + + Vern +</PRE> + + + +<H2><A NAME="SEC110" HREF="flex_toc.html#TOC110">unnamed-faq-57</A></H2> + +<PRE> +@verbatim +To: "Marty Leisner" <leisner@sdsp.mc.xerox.com> +Subject: Re: flex limitations +In-reply-to: Your message of Sat, 06 Sep 1997 11:27:21 PDT. +Date: Mon, 08 Sep 1997 11:38:08 PDT +From: Vern Paxson <vern> + +> %% +> [a-zA-Z]+ /* skip a line */ +> { printf("got %s\n", yytext); } +> %% + +What version of flex are you using? If I feed this to 2.5.4, it complains: + + "bug.l", line 5: EOF encountered inside an action + "bug.l", line 5: unrecognized rule + "bug.l", line 5: fatal parse error + +Not the world's greatest error message, but it manages to flag the problem. + +(With the introduction of start condition scopes, flex can't accommodate +an action on a separate line, since it's ambiguous with an indented rule.) + +You can get 2.5.4 from ftp.ee.lbl.gov. + + Vern +</PRE> + + + +<H2><A NAME="SEC111" HREF="flex_toc.html#TOC111">unnamed-faq-58</A></H2> + +<PRE> +@verbatim +To: uocarroll@deagostini.co.uk (Ultan O'Carroll) +Subject: Re: Flex repositries +In-reply-to: Your message of Fri, 12 Sep 1997 15:02:28 PDT. +Date: Fri, 12 Sep 1997 10:31:50 PDT +From: Vern Paxson <vern> + +> before I start beavering away I wonder if you know of any +> place/libraries for flex +> desciption files that might already do this or give me a head start ? + +Unfortunately, no, I don't. You might try asking on comp.compilers. + + Vern +</PRE> + + + +<H2><A NAME="SEC112" HREF="flex_toc.html#TOC112">unnamed-faq-59</A></H2> + +<PRE> +@verbatim +To: Adoram Rogel <adoram@hybridge.com> +Subject: Re: Conditional compiling in the definitions section +In-reply-to: Your message of Thu, 25 Sep 1997 11:22:42 PDT. +Date: Thu, 25 Sep 1997 10:56:31 PDT +From: Vern Paxson <vern> + +> I'm trying to combine two large lex files that now differ only in +> about 10 lines in the definitions section. +> I would like to have something like this: +> #ifdef FFF +> it \<IT\> +> #else +> it \<I\> +> #endif +> +> Now, I can't add states for these, as I have already too many states +> and the program is very complicated, and I won't be able to handle +> 10 or 20 more states. +> +> Any trick to do this ? + +You might try using m4, or the C preprocessor plus a sed script to +clean up the result (strip out the #line's). + + Vern +</PRE> + + + +<H2><A NAME="SEC113" HREF="flex_toc.html#TOC113">unnamed-faq-60</A></H2> + +<PRE> +@verbatim +To: Steve Antoch <SteveAn@visio.com> +Subject: Re: lex and yacc grammars +In-reply-to: Your message of Mon, 17 Nov 1997 15:31:25 PST. +Date: Mon, 17 Nov 1997 15:27:01 PST +From: Vern Paxson <vern> + +> Would you happen to know where I can find grammars for lex and yacc? + +The flex sources have a grammar for (f)lex. Dunno about yacc, + + Vern +</PRE> + + + +<H2><A NAME="SEC114" HREF="flex_toc.html#TOC114">unnamed-faq-61</A></H2> + +<PRE> +@verbatim +To: Bryan Housel <bryan@drawcomp.com> +Subject: Re: Question about Flex v2.5 +In-reply-to: Your message of Tue, 11 Nov 1997 21:30:23 PST. +Date: Mon, 17 Nov 1997 17:12:21 PST +From: Vern Paxson <vern> + +> It prints one of those "end of buffer.." messages for each character in the +> token... + +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(). + +Solution: override LexerInput() with a version that returns whole buffers. + + Vern +</PRE> + + + +<H2><A NAME="SEC115" HREF="flex_toc.html#TOC115">unnamed-faq-62</A></H2> + +<PRE> +@verbatim +To: Georg.Rehm@CL-KI.Uni-Osnabrueck.DE +Subject: Re: Flex maximums +In-reply-to: Your message of Mon, 17 Nov 1997 17:16:06 PST. +Date: Mon, 17 Nov 1997 17:16:15 PST +From: Vern Paxson <vern> + +> I took a quick look into the flex-sources and altered some #defines in +> flexdefs.h: +> +> #define INITIAL_MNS 64000 +> #define MNS_INCREMENT 1024000 +> #define MAXIMUM_MNS 64000 + +The things to fix are to add a couple of zeroes to: + +#define JAMSTATE -32766 /* marks a reference to the state that always jams */ +#define MAXIMUM_MNS 31999 +#define BAD_SUBSCRIPT -32767 +#define MAX_SHORT 32700 + +and, if you get complaints about too many rules, make the following change too: + + #define YY_TRAILING_MASK 0x200000 + #define YY_TRAILING_HEAD_MASK 0x400000 + +- Vern +</PRE> + + + +<H2><A NAME="SEC116" HREF="flex_toc.html#TOC116">unnamed-faq-63</A></H2> + +<PRE> +@verbatim +To: jimmey@lexis-nexis.com (Jimmey Todd) +Subject: Re: FLEX question regarding istream vs ifstream +In-reply-to: Your message of Mon, 08 Dec 1997 15:54:15 PST. +Date: Mon, 15 Dec 1997 13:21:35 PST +From: Vern Paxson <vern> + +> stdin_handle = YY_CURRENT_BUFFER; +> ifstream fin( "aFile" ); +> yy_switch_to_buffer( yy_create_buffer( fin, YY_BUF_SIZE ) ); +> +> What I'm wanting to do, is pass the contents of a file thru one set +> of rules and then pass stdin thru another set... It works great if, I +> don't use the C++ classes. But since everything else that I'm doing is +> in C++, I thought I'd be consistent. +> +> The problem is that 'yy_create_buffer' is expecting an istream* as it's +> first argument (as stated in the man page). However, fin is a ifstream +> object. Any ideas on what I might be doing wrong? Any help would be +> appreciated. Thanks!! + +You need to pass &fin, to turn it into an ifstream* instead of an ifstream. +Then its type will be compatible with the expected istream*, because ifstream +is derived from istream. + + Vern +</PRE> + + + +<H2><A NAME="SEC117" HREF="flex_toc.html#TOC117">unnamed-faq-64</A></H2> + +<PRE> +@verbatim +To: Enda Fadian <fadiane@piercom.ie> +Subject: Re: Question related to Flex man page? +In-reply-to: Your message of Tue, 16 Dec 1997 15:17:34 PST. +Date: Tue, 16 Dec 1997 14:17:09 PST +From: Vern Paxson <vern> + +> Can you explain to me what is ment by a long-jump in relation to flex? + +Using the longjmp() function while inside yylex() or a routine called by it. + +> what is the flex activation frame. + +Just yylex()'s stack frame. + +> As far as I can see yyrestart will bring me back to the sart of the input +> file and using flex++ isnot really an option! + +No, yyrestart() doesn't imply a rewind, even though its name might sound +like it does. It tells the scanner to flush its internal buffers and +start reading from the given file at its present location. + + Vern +</PRE> + + + +<H2><A NAME="SEC118" HREF="flex_toc.html#TOC118">unnamed-faq-65</A></H2> + +<PRE> +@verbatim +To: hassan@larc.info.uqam.ca (Hassan Alaoui) +Subject: Re: Need urgent Help +In-reply-to: Your message of Sat, 20 Dec 1997 19:38:19 PST. +Date: Sun, 21 Dec 1997 21:30:46 PST +From: Vern Paxson <vern> + +> /usr/lib/yaccpar: In function `int yyparse()': +> /usr/lib/yaccpar:184: warning: implicit declaration of function `int yylex(...)' +> +> ld: Undefined symbol +> _yylex +> _yyparse +> _yyin + +This is a known problem with Solaris C++ (and/or Solaris yacc). I believe +the fix is to explicitly insert some 'extern "C"' statements for the +corresponding routines/symbols. + + Vern +</PRE> + + + +<H2><A NAME="SEC119" HREF="flex_toc.html#TOC119">unnamed-faq-66</A></H2> + +<PRE> +@verbatim +To: mc0307@mclink.it +Cc: gnu@prep.ai.mit.edu +Subject: Re: [mc0307@mclink.it: Help request] +In-reply-to: Your message of Fri, 12 Dec 1997 17:57:29 PST. +Date: Sun, 21 Dec 1997 22:33:37 PST +From: Vern Paxson <vern> + +> This is my definition for float and integer types: +> . . . +> NZD [1-9] +> ... +> I've tested my program on other lex version (on UNIX Sun Solaris an HP +> UNIX) and it work well, so I think that my definitions are correct. +> There are any differences between Lex and Flex? + +There are indeed differences, as discussed in the man page. The one +you are probably running into is that when flex expands a name definition, +it puts parentheses around the expansion, while lex does not. There's +an example in the man page of how this can lead to different matching. +Flex's behavior complies with the POSIX standard (or at least with the +last POSIX draft I saw). + + Vern +</PRE> + + + +<H2><A NAME="SEC120" HREF="flex_toc.html#TOC120">unnamed-faq-67</A></H2> + +<PRE> +@verbatim +To: hassan@larc.info.uqam.ca (Hassan Alaoui) +Subject: Re: Thanks +In-reply-to: Your message of Mon, 22 Dec 1997 16:06:35 PST. +Date: Mon, 22 Dec 1997 14:35:05 PST +From: Vern Paxson <vern> + +> Thank you very much for your help. I compile and link well with C++ while +> declaring 'yylex ...' extern, But a little problem remains. I get a +> segmentation default when executing ( I linked with lfl library) while it +> works well when using LEX instead of flex. Do you have some ideas about the +> reason for this ? + +The one possible reason for this that comes to mind is if you've defined +yytext as "extern char yytext[]" (which is what lex uses) instead of +"extern char *yytext" (which is what flex uses). If it's not that, then +I'm afraid I don't know what the problem might be. + + Vern +</PRE> + + + +<H2><A NAME="SEC121" HREF="flex_toc.html#TOC121">unnamed-faq-68</A></H2> + +<PRE> +@verbatim +To: "Bart Niswonger" <NISWONGR@almaden.ibm.com> +Subject: Re: flex 2.5: c++ scanners & start conditions +In-reply-to: Your message of Tue, 06 Jan 1998 10:34:21 PST. +Date: Tue, 06 Jan 1998 19:19:30 PST +From: Vern Paxson <vern> + +> The problem is that when I do this (using %option c++) start +> conditions seem to not apply. + +The BEGIN macro modifies the yy_start variable. For C scanners, this +is a static with scope visible through the whole file. For C++ scanners, +it's a member variable, so it only has visible scope within a member +function. Your lexbegin() routine is not a member function when you +build a C++ scanner, so it's not modifying the correct yy_start. The +diagnostic that indicates this is that you found you needed to add +a declaration of yy_start in order to get your scanner to compile when +using C++; instead, the correct fix is to make lexbegin() a member +function (by deriving from yyFlexLexer). + + Vern +</PRE> + + + +<H2><A NAME="SEC122" HREF="flex_toc.html#TOC122">unnamed-faq-69</A></H2> + +<PRE> +@verbatim +To: "Boris Zinin" <boris@ippe.rssi.ru> +Subject: Re: current position in flex buffer +In-reply-to: Your message of Mon, 12 Jan 1998 18:58:23 PST. +Date: Mon, 12 Jan 1998 12:03:15 PST +From: Vern Paxson <vern> + +> The problem is how to determine the current position in flex active +> buffer when a rule is matched.... + +You will need to keep track of this explicitly, such as by redefining +YY_USER_ACTION to count the number of characters matched. + +The latest flex release, by the way, is 2.5.4, available from ftp.ee.lbl.gov. + + Vern +</PRE> + + + +<H2><A NAME="SEC123" HREF="flex_toc.html#TOC123">unnamed-faq-70</A></H2> + +<PRE> +@verbatim +To: Bik.Dhaliwal@bis.org +Subject: Re: Flex question +In-reply-to: Your message of Mon, 26 Jan 1998 13:05:35 PST. +Date: Tue, 27 Jan 1998 22:41:52 PST +From: Vern Paxson <vern> + +> That requirement involves knowing +> the character position at which a particular token was matched +> in the lexer. + +The way you have to do this is by explicitly keeping track of where +you are in the file, by counting the number of characters scanned +for each token (available in yyleng). It may prove convenient to +do this by redefining YY_USER_ACTION, as described in the manual. + + Vern +</PRE> + + + +<H2><A NAME="SEC124" HREF="flex_toc.html#TOC124">unnamed-faq-71</A></H2> + +<PRE> +@verbatim +To: Vladimir Alexiev <vladimir@cs.ualberta.ca> +Subject: Re: flex: how to control start condition from parser? +In-reply-to: Your message of Mon, 26 Jan 1998 05:50:16 PST. +Date: Tue, 27 Jan 1998 22:45:37 PST +From: Vern Paxson <vern> + +> It seems useful for the parser to be able to tell the lexer about such +> context dependencies, because then they don't have to be limited to +> local or sequential context. + +One way to do this is to have the parser call a stub routine that's +included in the scanner's .l file, and consequently that has access ot +BEGIN. The only ugliness is that the parser can't pass in the state +it wants, because those aren't visible - but if you don't have many +such states, then using a different set of names doesn't seem like +to much of a burden. + +While generating a .h file like you suggests is certainly cleaner, +flex development has come to a virtual stand-still :-(, so a workaround +like the above is much more pragmatic than waiting for a new feature. + + Vern +</PRE> + + + +<H2><A NAME="SEC125" HREF="flex_toc.html#TOC125">unnamed-faq-72</A></H2> + +<PRE> +@verbatim +To: Barbara Denny <denny@3com.com> +Subject: Re: freebsd flex bug? +In-reply-to: Your message of Fri, 30 Jan 1998 12:00:43 PST. +Date: Fri, 30 Jan 1998 12:42:32 PST +From: Vern Paxson <vern> + +> lex.yy.c:1996: parse error before `=' + +This is the key, identifying this error. (It may help to pinpoint +it by using flex -L, so it doesn't generate #line directives in its +output.) I will bet you heavy money that you have a start condition +name that is also a variable name, or something like that; flex spits +out #define's for each start condition name, mapping them to a number, +so you can wind up with: + + %x foo + %% + ... + %% + void bar() + { + int foo = 3; + } + +and the penultimate will turn into "int 1 = 3" after C preprocessing, +since flex will put "#define foo 1" in the generated scanner. + + Vern +</PRE> + + + +<H2><A NAME="SEC126" HREF="flex_toc.html#TOC126">unnamed-faq-73</A></H2> + +<PRE> +@verbatim +To: Maurice Petrie <mpetrie@infoscigroup.com> +Subject: Re: Lost flex .l file +In-reply-to: Your message of Mon, 02 Feb 1998 14:10:01 PST. +Date: Mon, 02 Feb 1998 11:15:12 PST +From: Vern Paxson <vern> + +> I am curious as to +> whether there is a simple way to backtrack from the generated source to +> reproduce the lost list of tokens we are searching on. + +In theory, it's straight-forward to go from the DFA representation +back to a regular-expression representation - the two are isomorphic. +In practice, a huge headache, because you have to unpack all the tables +back into a single DFA representation, and then write a program to munch +on that and translate it into an RE. + +Sorry for the less-than-happy news ... + + Vern +</PRE> + + + +<H2><A NAME="SEC127" HREF="flex_toc.html#TOC127">unnamed-faq-74</A></H2> + +<PRE> +@verbatim +To: jimmey@lexis-nexis.com (Jimmey Todd) +Subject: Re: Flex performance question +In-reply-to: Your message of Thu, 19 Feb 1998 11:01:17 PST. +Date: Thu, 19 Feb 1998 08:48:51 PST +From: Vern Paxson <vern> + +> What I have found, is that the smaller the data chunk, the faster the +> program executes. This is the opposite of what I expected. Should this be +> happening this way? + +This is exactly what will happen if your input file has embedded NULs. +From the man page: + +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. + +So that's the first thing to look for. + + Vern +</PRE> + + + +<H2><A NAME="SEC128" HREF="flex_toc.html#TOC128">unnamed-faq-75</A></H2> + +<PRE> +@verbatim +To: jimmey@lexis-nexis.com (Jimmey Todd) +Subject: Re: Flex performance question +In-reply-to: Your message of Thu, 19 Feb 1998 11:01:17 PST. +Date: Thu, 19 Feb 1998 15:42:25 PST +From: Vern Paxson <vern> + +So there are several problems. + +First, to go fast, you want to match as much text as possible, which +your scanners don't in the case that what they're scanning is *not* +a <RN> tag. So you want a rule like: + + [^<]+ + +Second, C++ scanners are particularly slow if they're interactive, +which they are by default. Using -B speeds it up by a factor of 3-4 +on my workstation. + +Third, C++ scanners that use the istream interface are slow, because +of how poorly implemented istream's are. I built two versions of +the following scanner: + + %% + .*\n + .* + %% + +and the C version inhales a 2.5MB file on my workstation in 0.8 seconds. +The C++ istream version, using -B, takes 3.8 seconds. + + Vern +</PRE> + + + +<H2><A NAME="SEC129" HREF="flex_toc.html#TOC129">unnamed-faq-76</A></H2> + +<PRE> +@verbatim +To: "Frescatore, David (CRD, TAD)" <frescatore@exc01crdge.crd.ge.com> +Subject: Re: FLEX 2.5 & THE YEAR 2000 +In-reply-to: Your message of Wed, 03 Jun 1998 11:26:22 PDT. +Date: Wed, 03 Jun 1998 10:22:26 PDT +From: Vern Paxson <vern> + +> I am researching the Y2K problem with General Electric R&D +> and need to know if there are any known issues concerning +> the above mentioned software and Y2K regardless of version. + +There shouldn't be, all it ever does with the date is ask the system +for it and then print it out. + + Vern +</PRE> + + + +<H2><A NAME="SEC130" HREF="flex_toc.html#TOC130">unnamed-faq-77</A></H2> + +<PRE> +@verbatim +To: "Hans Dermot Doran" <htd@ibhdoran.com> +Subject: Re: flex problem +In-reply-to: Your message of Wed, 15 Jul 1998 21:30:13 PDT. +Date: Tue, 21 Jul 1998 14:23:34 PDT +From: Vern Paxson <vern> + +> To overcome this, I gets() the stdin into a string and lex the string. The +> string is lexed OK except that the end of string isn't lexed properly +> (yy_scan_string()), that is the lexer dosn't recognise the end of string. + +Flex doesn't contain mechanisms for recognizing buffer endpoints. But if +you use fgets instead (which you should anyway, to protect against buffer +overflows), then the final \n will be preserved in the string, and you can +scan that in order to find the end of the string. + + Vern +</PRE> + + + +<H2><A NAME="SEC131" HREF="flex_toc.html#TOC131">unnamed-faq-78</A></H2> + +<PRE> +@verbatim +To: soumen@almaden.ibm.com +Subject: Re: Flex++ 2.5.3 instance member vs. static member +In-reply-to: Your message of Mon, 27 Jul 1998 02:10:04 PDT. +Date: Tue, 28 Jul 1998 01:10:34 PDT +From: Vern Paxson <vern> + +> %{ +> int mylineno = 0; +> %} +> ws [ \t]+ +> alpha [A-Za-z] +> dig [0-9] +> %% +> +> Now you'd expect mylineno to be a member of each instance of class +> yyFlexLexer, but is this the case? A look at the lex.yy.cc file seems to +> indicate otherwise; unless I am missing something the declaration of +> mylineno seems to be outside any class scope. +> +> How will this work if I want to run a multi-threaded application with each +> thread creating a FlexLexer instance? + +Derive your own subclass and make mylineno a member variable of it. + + Vern +</PRE> + + + +<H2><A NAME="SEC132" HREF="flex_toc.html#TOC132">unnamed-faq-79</A></H2> + +<PRE> +@verbatim +To: Adoram Rogel <adoram@hybridge.com> +Subject: Re: More than 32K states change hangs +In-reply-to: Your message of Tue, 04 Aug 1998 16:55:39 PDT. +Date: Tue, 04 Aug 1998 22:28:45 PDT +From: Vern Paxson <vern> + +> Vern Paxson, +> +> I followed your advice, posted on Usenet bu you, and emailed to me +> personally by you, on how to overcome the 32K states limit. I'm running +> on Linux machines. +> I took the full source of version 2.5.4 and did the following changes in +> flexdef.h: +> #define JAMSTATE -327660 +> #define MAXIMUM_MNS 319990 +> #define BAD_SUBSCRIPT -327670 +> #define MAX_SHORT 327000 +> +> and compiled. +> All looked fine, including check and bigcheck, so I installed. + +Hmmm, you shouldn't increase MAX_SHORT, though looking through my email +archives I see that I did indeed recommend doing so. Try setting it back +to 32700; that should suffice that you no longer need -Ca. If it still +hangs, then the interesting question is - where? + +> Compiling the same hanged program with a out-of-the-box (RedHat 4.2 +> distribution of Linux) +> flex 2.5.4 binary works. + +Since Linux comes with source code, you should diff it against what +you have to see what problems they missed. + +> Should I always compile with the -Ca option now ? even short and simple +> filters ? + +No, definitely not. It's meant to be for those situations where you +absolutely must squeeze every last cycle out of your scanner. + + Vern +</PRE> + + + +<H2><A NAME="SEC133" HREF="flex_toc.html#TOC133">unnamed-faq-80</A></H2> + +<PRE> +@verbatim +To: "Schmackpfeffer, Craig" <Craig.Schmackpfeffer@usa.xerox.com> +Subject: Re: flex output for static code portion +In-reply-to: Your message of Tue, 11 Aug 1998 11:55:30 PDT. +Date: Mon, 17 Aug 1998 23:57:42 PDT +From: Vern Paxson <vern> + +> I would like to use flex under the hood to generate a binary file +> containing the data structures that control the parse. + +This has been on the wish-list for a long time. In principle it's +straight-forward - you redirect mkdata() et al's I/O to another file, +and modify the skeleton to have a start-up function that slurps these +into dynamic arrays. The concerns are (1) the scanner generation code +is hairy and full of corner cases, so it's easy to get surprised when +going down this path :-( ; and (2) being careful about buffering so +that when the tables change you make sure the scanner starts in the +correct state and reading at the right point in the input file. + +> I was wondering if you know of anyone who has used flex in this way. + +I don't - but it seems like a reasonable project to undertake (unlike +numerous other flex tweaks :-). + + Vern +</PRE> + + + +<H2><A NAME="SEC134" HREF="flex_toc.html#TOC134">unnamed-faq-81</A></H2> + +<PRE> +@verbatim +Received: from 131.173.17.11 (131.173.17.11 [131.173.17.11]) + by ee.lbl.gov (8.9.1/8.9.1) with ESMTP id AAA03838 + for <vern@ee.lbl.gov>; Thu, 20 Aug 1998 00:47:57 -0700 (PDT) +Received: from hal.cl-ki.uni-osnabrueck.de (hal.cl-ki.Uni-Osnabrueck.DE [131.173.141.2]) + by deimos.rz.uni-osnabrueck.de (8.8.7/8.8.8) with ESMTP id JAA34694 + for <vern@ee.lbl.gov>; Thu, 20 Aug 1998 09:47:55 +0200 +Received: (from georg@localhost) by hal.cl-ki.uni-osnabrueck.de (8.6.12/8.6.12) id JAA34834 for vern@ee.lbl.gov; Thu, 20 Aug 1998 09:47:54 +0200 +From: Georg Rehm <georg@hal.cl-ki.uni-osnabrueck.de> +Message-Id: <199808200747.JAA34834@hal.cl-ki.uni-osnabrueck.de> +Subject: "flex scanner push-back overflow" +To: vern@ee.lbl.gov +Date: Thu, 20 Aug 1998 09:47:54 +0200 (MEST) +Reply-To: Georg.Rehm@CL-KI.Uni-Osnabrueck.DE +X-NoJunk: Do NOT send commercial mail, spam or ads to this address! +X-URL: http://www.cl-ki.uni-osnabrueck.de/~georg/ +X-Mailer: ELM [version 2.4ME+ PL28 (25)] +MIME-Version: 1.0 +Content-Type: text/plain; charset=US-ASCII +Content-Transfer-Encoding: 7bit + +Hi Vern, + +Yesterday, I encountered a strange problem: I use the macro processor m4 +to include some lengthy lists into a .l file. Following is a flex macro +definition that causes some serious pain in my neck: + +AUTHOR ("A. Boucard / L. Boucard"|"A. Dastarac / M. Levent"|"A.Boucaud / L.Boucaud"|"Abderrahim Lamchichi"|"Achmat Dangor"|"Adeline Toullier"|"Adewale Maja-Pearce"|"Ahmed Ziri"|"Akram Ellyas"|"Alain Bihr"|"Alain Gresh"|"Alain Guillemoles"|"Alain Joxe"|"Alain Morice"|"Alain Renon"|"Alain Zecchini"|"Albert Memmi"|"Alberto Manguel"|"Alex De Waal"|"Alfonso Artico"| [...]) + +The complete list contains about 10kB. When I try to "flex" this file +(on a Solaris 2.6 machine, using a modified flex 2.5.4 (I only increased +some of the predefined values in flexdefs.h) I get the error: + +myflex/flex -8 sentag.tmp.l +flex scanner push-back overflow + +When I remove the slashes in the macro definition everything works fine. +As I understand it, the double quotes escape the slash-character so it +really means "/" and not "trailing context". Furthermore, I tried to +escape the slashes with backslashes, but with no use, the same error message +appeared when flexing the code. + +Do you have an idea what's going on here? + +Greetings from Germany, + Georg +-- +Georg Rehm georg@cl-ki.uni-osnabrueck.de +Institute for Semantic Information Processing, University of Osnabrueck, FRG +</PRE> + + + +<H2><A NAME="SEC135" HREF="flex_toc.html#TOC135">unnamed-faq-82</A></H2> + +<PRE> +@verbatim +To: Georg.Rehm@CL-KI.Uni-Osnabrueck.DE +Subject: Re: "flex scanner push-back overflow" +In-reply-to: Your message of Thu, 20 Aug 1998 09:47:54 PDT. +Date: Thu, 20 Aug 1998 07:05:35 PDT +From: Vern Paxson <vern> + +> myflex/flex -8 sentag.tmp.l +> flex scanner push-back overflow + +Flex itself uses a flex scanner. That scanner is running out of buffer +space when it tries to unput() the humongous macro you've defined. When +you remove the '/'s, you make it small enough so that it fits in the buffer; +removing spaces would do the same thing. + +The fix is to either rethink how come you're using such a big macro and +perhaps there's another/better way to do it; or to rebuild flex's own +scan.c with a larger value for + + #define YY_BUF_SIZE 16384 + +- Vern +</PRE> + + + +<H2><A NAME="SEC136" HREF="flex_toc.html#TOC136">unnamed-faq-83</A></H2> + +<PRE> +@verbatim +To: Jan Kort <jan@research.techforce.nl> +Subject: Re: Flex +In-reply-to: Your message of Fri, 04 Sep 1998 12:18:43 +0200. +Date: Sat, 05 Sep 1998 00:59:49 PDT +From: Vern Paxson <vern> + +> %% +> +> "TEST1\n" { fprintf(stderr, "TEST1\n"); yyless(5); } +> ^\n { fprintf(stderr, "empty line\n"); } +> . { } +> \n { fprintf(stderr, "new line\n"); } +> +> %% +> -- input --------------------------------------- +> TEST1 +> -- output -------------------------------------- +> TEST1 +> empty line +> ------------------------------------------------ + +IMHO, it's not clear whether or not this is in fact a bug. It depends +on whether you view yyless() as backing up in the input stream, or as +pushing new characters onto the beginning of the input stream. Flex +interprets it as the latter (for implementation convenience, I'll admit), +and so considers the newline as in fact matching at the beginning of a +line, as after all the last token scanned an entire line and so the +scanner is now at the beginning of a new line. + +I agree that this is counter-intuitive for yyless(), given its +functional description (it's less so for unput(), depending on whether +you're unput()'ing new text or scanned text). But I don't plan to +change it any time soon, as it's a pain to do so. Consequently, +you do indeed need to use yy_set_bol() and YY_AT_BOL() to tweak +your scanner into the behavior you desire. + +Sorry for the less-than-completely-satisfactory answer. + + Vern +</PRE> + + + +<H2><A NAME="SEC137" HREF="flex_toc.html#TOC137">unnamed-faq-84</A></H2> + +<PRE> +@verbatim +To: Patrick Krusenotto <krusenot@mac-info-link.de> +Subject: Re: Problems with restarting flex-2.5.2-generated scanner +In-reply-to: Your message of Thu, 24 Sep 1998 10:14:07 PDT. +Date: Thu, 24 Sep 1998 23:28:43 PDT +From: Vern Paxson <vern> + +> I am using flex-2.5.2 and bison 1.25 for Solaris and I am desperately +> trying to make my scanner restart with a new file after my parser stops +> with a parse error. When my compiler restarts, the parser always +> receives the token after the token (in the old file!) that caused the +> parser error. + +I suspect the problem is that your parser has read ahead in order +to attempt to resolve an ambiguity, and when it's restarted it picks +up with that token rather than reading a fresh one. If you're using +yacc, then the special "error" production can sometimes be used to +consume tokens in an attempt to get the parser into a consistent state. + + Vern +</PRE> + + + +<H2><A NAME="SEC138" HREF="flex_toc.html#TOC138">unnamed-faq-85</A></H2> + +<PRE> +@verbatim +To: Henric Jungheim <junghelh@pe-nelson.com> +Subject: Re: flex 2.5.4a +In-reply-to: Your message of Tue, 27 Oct 1998 16:41:42 PST. +Date: Tue, 27 Oct 1998 16:50:14 PST +From: Vern Paxson <vern> + +> This brings up a feature request: How about a command line +> option to specify the filename when reading from stdin? That way one +> doesn't need to create a temporary file in order to get the "#line" +> directives to make sense. + +Use -o combined with -t (per the man page description of -o). + +> P.S., Is there any simple way to use non-blocking IO to parse multiple +> streams? + +Simple, no. + +One approach might be to return a magic character on EWOULDBLOCK and +have a rule + + .*<magic-character> // put back .*, eat magic character + +This is off the top of my head, not sure it'll work. + + Vern +</PRE> + + + +<H2><A NAME="SEC139" HREF="flex_toc.html#TOC139">unnamed-faq-86</A></H2> + +<PRE> +@verbatim +To: "Repko, Billy D" <billy.d.repko@intel.com> +Subject: Re: Compiling scanners +In-reply-to: Your message of Wed, 13 Jan 1999 10:52:47 PST. +Date: Thu, 14 Jan 1999 00:25:30 PST +From: Vern Paxson <vern> + +> It appears that maybe it cannot find the lfl library. + +The Makefile in the distribution builds it, so you should have it. +It's exceedingly trivial, just a main() that calls yylex() and +a yyrap() that always returns 1. + +> %% +> \n ++num_lines; ++num_chars; +> . ++num_chars; + +You can't indent your rules like this - that's where the errors are coming +from. Flex copies indented text to the output file, it's how you do things +like + + int num_lines_seen = 0; + +to declare local variables. + + Vern +</PRE> + + + +<H2><A NAME="SEC140" HREF="flex_toc.html#TOC140">unnamed-faq-87</A></H2> + +<PRE> +@verbatim +To: Erick Branderhorst <Erick.Branderhorst@asml.nl> +Subject: Re: flex input buffer +In-reply-to: Your message of Tue, 09 Feb 1999 13:53:46 PST. +Date: Tue, 09 Feb 1999 21:03:37 PST +From: Vern Paxson <vern> + +> In the flex.skl file the size of the default input buffers is set. Can you +> explain why this size is set and why it is such a high number. + +It's large to optimize performance when scanning large files. You can +safely make it a lot lower if needed. + + Vern +</PRE> + + + +<H2><A NAME="SEC141" HREF="flex_toc.html#TOC141">unnamed-faq-88</A></H2> + +<PRE> +@verbatim +To: "Guido Minnen" <guidomi@cogs.susx.ac.uk> +Subject: Re: Flex error message +In-reply-to: Your message of Wed, 24 Feb 1999 15:31:46 PST. +Date: Thu, 25 Feb 1999 00:11:31 PST +From: Vern Paxson <vern> + +> I'm extending a larger scanner written in Flex and I keep running into +> problems. More specifically, I get the error message: +> "flex: input rules are too complicated (>= 32000 NFA states)" + +Increase the definitions in flexdef.h for: + +#define JAMSTATE -32766 /* marks a reference to the state that always j +ams */ +#define MAXIMUM_MNS 31999 +#define BAD_SUBSCRIPT -32767 + +recompile everything, and it should all work. + + Vern +</PRE> + + + +<H2><A NAME="SEC142" HREF="flex_toc.html#TOC142">unnamed-faq-90</A></H2> + +<PRE> +@verbatim +To: "Dmitriy Goldobin" <gold@ems.chel.su> +Subject: Re: FLEX trouble +In-reply-to: Your message of Mon, 31 May 1999 18:44:49 PDT. +Date: Tue, 01 Jun 1999 00:15:07 PDT +From: Vern Paxson <vern> + +> I have a trouble with FLEX. Why rule "/*".*"*/" work properly,=20 +> but rule "/*"(.|\n)*"*/" don't work ? + +The second of these will have to scan the entire input stream (because +"(.|\n)*" matches an arbitrary amount of any text) in order to see if +it ends with "*/", terminating the comment. That potentially will overflow +the input buffer. + +> More complex rule "/*"([^*]|(\*/[^/]))*"*/ give an error +> 'unrecognized rule'. + +You can't use the '/' operator inside parentheses. It's not clear +what "(a/b)*" actually means. + +> I now use workaround with state <comment>, but single-rule is +> better, i think. + +Single-rule is nice but will always have the problem of either setting +restrictions on comments (like not allowing multi-line comments) and/or +running the risk of consuming the entire input stream, as noted above. + + Vern +</PRE> + + + +<H2><A NAME="SEC143" HREF="flex_toc.html#TOC143">unnamed-faq-91</A></H2> + +<PRE> +@verbatim +Received: from mc-qout4.whowhere.com (mc-qout4.whowhere.com [209.185.123.18]) + by ee.lbl.gov (8.9.3/8.9.3) with SMTP id IAA05100 + for <vern@ee.lbl.gov>; Tue, 15 Jun 1999 08:56:06 -0700 (PDT) +Received: from Unknown/Local ([?.?.?.?]) by my-deja.com; Tue Jun 15 08:55:43 1999 +To: vern@ee.lbl.gov +Date: Tue, 15 Jun 1999 08:55:43 -0700 +From: "Aki Niimura" <neko@my-deja.com> +Message-ID: <KNONDOHDOBGAEAAA@my-deja.com> +Mime-Version: 1.0 +Cc: +X-Sent-Mail: on +Reply-To: +X-Mailer: MailCity Service +Subject: A question on flex C++ scanner +X-Sender-Ip: 12.72.207.61 +Organization: My Deja Email (http://www.my-deja.com:80) +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit + +Dear Dr. Paxon, + +I have been using flex for years. +It works very well on many projects. +Most case, I used it to generate a scanner on C language. +However, one project I needed to generate a scanner +on C++ lanuage. Thanks to your enhancement, flex did +the job. + +Currently, I'm working on enhancing my previous project. +I need to deal with multiple input streams (recursive +inclusion) in this scanner (C++). +I did similar thing for another scanner (C) as you +explained in your documentation. + +The generated scanner (C++) has necessary methods: +- switch_to_buffer(struct yy_buffer_state *b) +- yy_create_buffer(istream *is, int sz) +- yy_delete_buffer(struct yy_buffer_state *b) + +However, I couldn't figure out how to access current +buffer (yy_current_buffer). + +yy_current_buffer is a protected member of yyFlexLexer. +I can't access it directly. +Then, I thought yy_create_buffer() with is = 0 might +return current stream buffer. But it seems not as far +as I checked the source. (flex 2.5.4) + +I went through the Web in addition to Flex documentation. +However, it hasn't been successful, so far. + +It is not my intention to bother you, but, can you +comment about how to obtain the current stream buffer? + +Your response would be highly appreciated. + +Best regards, +Aki Niimura + +--== Sent via Deja.com http://www.deja.com/ ==-- +Share what you know. Learn what you don't. +</PRE> + + + +<H2><A NAME="SEC144" HREF="flex_toc.html#TOC144">unnamed-faq-92</A></H2> + +<PRE> +@verbatim +To: neko@my-deja.com +Subject: Re: A question on flex C++ scanner +In-reply-to: Your message of Tue, 15 Jun 1999 08:55:43 PDT. +Date: Tue, 15 Jun 1999 09:04:24 PDT +From: Vern Paxson <vern> + +> However, I couldn't figure out how to access current +> buffer (yy_current_buffer). + +Derive your own subclass from yyFlexLexer. + + Vern +</PRE> + + + +<H2><A NAME="SEC145" HREF="flex_toc.html#TOC145">unnamed-faq-93</A></H2> + +<PRE> +@verbatim +To: "Stones, Darren" <Darren.Stones@nectech.co.uk> +Subject: Re: You're the man to see? +In-reply-to: Your message of Wed, 23 Jun 1999 11:10:29 PDT. +Date: Wed, 23 Jun 1999 09:01:40 PDT +From: Vern Paxson <vern> + +> I hope you can help me. I am using Flex and Bison to produce an interpreted +> language. However all goes well until I try to implement an IF statement or +> a WHILE. I cannot get this to work as the parser parses all the conditions +> eg. the TRUE and FALSE conditons to check for a rule match. So I cannot +> make a decision!! + +You need to use the parser to build a parse tree (= abstract syntax trwee), +and when that's all done you recursively evaluate the tree, binding variables +to values at that time. + + Vern +</PRE> + + + +<H2><A NAME="SEC146" HREF="flex_toc.html#TOC146">unnamed-faq-94</A></H2> + +<PRE> +@verbatim +To: Petr Danecek <petr@ics.cas.cz> +Subject: Re: flex - question +In-reply-to: Your message of Mon, 28 Jun 1999 19:21:41 PDT. +Date: Fri, 02 Jul 1999 16:52:13 PDT +From: Vern Paxson <vern> + +> file, it takes an enormous amount of time. It is funny, because the +> source code has only 12 rules!!! I think it looks like an exponencial +> growth. + +Right, that's the problem - some patterns (those with a lot of +ambiguity, where yours has because at any given time the scanner can +be in the middle of all sorts of combinations of the different +rules) blow up exponentially. + +For your rules, there is an easy fix. Change the ".*" that comes fater +the directory name to "[^ ]*". With that in place, the rules are no +longer nearly so ambiguous, because then once one of the directories +has been matched, no other can be matched (since they all require a +leading blank). + +If that's not an acceptable solution, then you can enter a start state +to pick up the .*\n after each directory is matched. + +Also note that for speed, you'll want to add a ".*" rule at the end, +otherwise rules that don't match any of the patterns will be matched +very slowly, a character at a time. + + Vern +</PRE> + + + +<H2><A NAME="SEC147" HREF="flex_toc.html#TOC147">unnamed-faq-95</A></H2> + +<PRE> +@verbatim +To: Tielman Koekemoer <tielman@spi.co.za> +Subject: Re: Please help. +In-reply-to: Your message of Thu, 08 Jul 1999 13:20:37 PDT. +Date: Thu, 08 Jul 1999 08:20:39 PDT +From: Vern Paxson <vern> + +> I was hoping you could help me with my problem. +> +> I tried compiling (gnu)flex on a Solaris 2.4 machine +> but when I ran make (after configure) I got an error. +> +> -------------------------------------------------------------- +> gcc -c -I. -I. -g -O parse.c +> ./flex -t -p ./scan.l >scan.c +> sh: ./flex: not found +> *** Error code 1 +> make: Fatal error: Command failed for target `scan.c' +> ------------------------------------------------------------- +> +> What's strange to me is that I'm only +> trying to install flex now. I then edited the Makefile to +> and changed where it says "FLEX = flex" to "FLEX = lex" +> ( lex: the native Solaris one ) but then it complains about +> the "-p" option. Is there any way I can compile flex without +> using flex or lex? +> +> Thanks so much for your time. + +You managed to step on the bootstrap sequence, which first copies +initscan.c to scan.c in order to build flex. Try fetching a fresh +distribution from ftp.ee.lbl.gov. (Or you can first try removing +".bootstrap" and doing a make again.) + + Vern +</PRE> + + + +<H2><A NAME="SEC148" HREF="flex_toc.html#TOC148">unnamed-faq-96</A></H2> + +<PRE> +@verbatim +To: Tielman Koekemoer <tielman@spi.co.za> +Subject: Re: Please help. +In-reply-to: Your message of Fri, 09 Jul 1999 09:16:14 PDT. +Date: Fri, 09 Jul 1999 00:27:20 PDT +From: Vern Paxson <vern> + +> First I removed .bootstrap (and ran make) - no luck. I downloaded the +> software but I still have the same problem. Is there anything else I +> could try. + +Try: + + cp initscan.c scan.c + touch scan.c + make scan.o + +If this last tries to first build scan.c from scan.l using ./flex, then +your "make" is broken, in which case compile scan.c to scan.o by hand. + + Vern +</PRE> + + + +<H2><A NAME="SEC149" HREF="flex_toc.html#TOC149">unnamed-faq-97</A></H2> + +<PRE> +@verbatim +To: Sumanth Kamenani <skamenan@crl.nmsu.edu> +Subject: Re: Error +In-reply-to: Your message of Mon, 19 Jul 1999 23:08:41 PDT. +Date: Tue, 20 Jul 1999 00:18:26 PDT +From: Vern Paxson <vern> + +> I am getting a compilation error. The error is given as "unknown symbol- yylex". + +The parser relies on calling yylex(), but you're instead using the C++ scanning +class, so you need to supply a yylex() "glue" function that calls an instance +scanner of the scanner (e.g., "scanner->yylex()"). + + Vern +</PRE> + + + +<H2><A NAME="SEC150" HREF="flex_toc.html#TOC150">unnamed-faq-98</A></H2> + +<PRE> +@verbatim +To: daniel@synchrods.synchrods.COM (Daniel Senderowicz) +Subject: Re: lex +In-reply-to: Your message of Mon, 22 Nov 1999 11:19:04 PST. +Date: Tue, 23 Nov 1999 15:54:30 PST +From: Vern Paxson <vern> + +Well, your problem is the + +switch (yybgin-yysvec-1) { /* witchcraft */ + +at the beginning of lex rules. "witchcraft" == "non-portable". It's +assuming knowledge of the AT&T lex's internal variables. + +For flex, you can probably do the equivalent using a switch on YYSTATE. + + Vern +</PRE> + + + +<H2><A NAME="SEC151" HREF="flex_toc.html#TOC151">unnamed-faq-99</A></H2> + +<PRE> +@verbatim +To: archow@hss.hns.com +Subject: Re: Regarding distribution of flex and yacc based grammars +In-reply-to: Your message of Sun, 19 Dec 1999 17:50:24 +0530. +Date: Wed, 22 Dec 1999 01:56:24 PST +From: Vern Paxson <vern> + +> When we provide the customer with an object code distribution, is it +> necessary for us to provide source +> for the generated C files from flex and bison since they are generated by +> flex and bison ? + +For flex, no. I don't know what the current state of this is for bison. + +> Also, is there any requrirement for us to neccessarily provide source for +> the grammar files which are fed into flex and bison ? + +Again, for flex, no. + +See the file "COPYING" in the flex distribution for the legalese. + + Vern +</PRE> + + + +<H2><A NAME="SEC152" HREF="flex_toc.html#TOC152">unnamed-faq-100</A></H2> + +<PRE> +@verbatim +To: Martin Gallwey <gallweym@hyperion.moe.ul.ie> +Subject: Re: Flex, and self referencing rules +In-reply-to: Your message of Sun, 20 Feb 2000 01:01:21 PST. +Date: Sat, 19 Feb 2000 18:33:16 PST +From: Vern Paxson <vern> + +> However, I do not use unput anywhere. I do use self-referencing +> rules like this: +> +> UnaryExpr ({UnionExpr})|("-"{UnaryExpr}) + +You can't do this - flex is *not* a parser like yacc (which does indeed +allow recursion), it is a scanner that's confined to regular expressions. + + Vern +</PRE> + + + +<H2><A NAME="SEC153" HREF="flex_toc.html#TOC153">unnamed-faq-101</A></H2> + +<PRE> +@verbatim +To: slg3@lehigh.edu (SAMUEL L. GULDEN) +Subject: Re: Flex problem +In-reply-to: Your message of Thu, 02 Mar 2000 12:29:04 PST. +Date: Thu, 02 Mar 2000 23:00:46 PST +From: Vern Paxson <vern> + +If this is exactly your program: + +> digit [0-9] +> digits {digit}+ +> whitespace [ \t\n]+ +> +> %% +> "[" { printf("open_brac\n");} +> "]" { printf("close_brac\n");} +> "+" { printf("addop\n");} +> "*" { printf("multop\n");} +> {digits} { printf("NUMBER = %s\n", yytext);} +> whitespace ; + +then the problem is that the last rule needs to be "{whitespace}" ! + + Vern +</PRE> + + + +<H1><A NAME="SEC154" HREF="flex_toc.html#TOC154">Appendices</A></H1> + + + +<H2><A NAME="SEC155" HREF="flex_toc.html#TOC155">Makefiles and Flex</A></H2> + +<P> +<A NAME="IDX463"></A> <P> @@ -6037,7 +8731,7 @@ <P> Modern @command{make} programs understand that <TT>`foo.l'</TT> is intended to generate <TT>`lex.yy.c'</TT> or <TT>`foo.c'</TT>, and will behave -accordingly<A NAME="DOCF2" HREF="flex_foot.html#FOOT2">(2)</A> and GNU @command{automake} are two such +accordingly<A NAME="DOCF3" HREF="flex_foot.html#FOOT3">(3)</A> and GNU @command{automake} are two such programs that provide implicit rules for flex-generated scanners.}. The following Makefile does not explicitly instruct @command{make} how to build <TT>`foo.c'</TT> from <TT>`foo.l'</TT>. Instead, it relies on the implicit rules of the @@ -6045,7 +8739,7 @@ <P> -<A NAME="IDX298"></A> +<A NAME="IDX464"></A> <PRE> @verbatim @@ -6065,7 +8759,7 @@ <P> -<A NAME="IDX299"></A> +<A NAME="IDX465"></A> <PRE> @verbatim @@ -6097,7 +8791,7 @@ <P> Finally, we provide a realistic example of a <CODE>flex</CODE> scanner used with a -<CODE>bison</CODE> parser<A NAME="DOCF3" HREF="flex_foot.html#FOOT3">(3)</A>. +<CODE>bison</CODE> parser<A NAME="DOCF4" HREF="flex_foot.html#FOOT4">(4)</A>. There is a tricky problem we have to deal with. Since a <CODE>flex</CODE> scanner will typically include a header file (e.g., <TT>`y.tab.h'</TT>) generated by the parser, we need to be sure that the header file is generated BEFORE the scanner @@ -6145,28 +8839,155 @@ -<H1><A NAME="SEC81" HREF="flex_toc.html#TOC81">Indices</A></H1> +<H2><A NAME="SEC156" HREF="flex_toc.html#TOC156">C Scanners with Bison Parsers</A></H2> +<P> +<A NAME="IDX466"></A> +<A NAME="IDX467"></A> +<A NAME="IDX468"></A> +<A NAME="IDX469"></A> +<A NAME="IDX470"></A> -<H2><A NAME="SEC82" HREF="flex_toc.html#TOC82">Concept Index</A></H2> <P> -<A NAME="IDX300"></A> -<A NAME="IDX301"></A> -<A NAME="IDX302"></A> -<A NAME="IDX303"></A> -<A NAME="IDX304"></A> -<A NAME="IDX305"></A> -<A NAME="IDX306"></A> -<A NAME="IDX307"></A> -<A NAME="IDX308"></A> -<A NAME="IDX309"></A> -<A NAME="IDX310"></A> +This section describes the <CODE>flex</CODE> features useful when integrating +<CODE>flex</CODE> with <CODE>GNU bison</CODE><A NAME="DOCF5" HREF="flex_foot.html#FOOT5">(5)</A>. +Skip this section if you are not using +<CODE>bison</CODE> with your scanner. Here we discuss only the <CODE>flex</CODE> +half of the <CODE>flex</CODE> and <CODE>bison</CODE> pair. We do not discuss +<CODE>bison</CODE> in any detail. For more information about generating +<CODE>bison</CODE> parsers, see section `Top' in <CITE>the GNU Bison Manual</CITE>. + + +<P> +A compatible <CODE>bison</CODE> scanner is generated by declaring <SAMP>`%option +bison-bridge'</SAMP> or by supplying <SAMP>`--bison-bridge'</SAMP> when invoking <CODE>flex</CODE> +from the command line. This instructs <CODE>flex</CODE> that the macros +<CODE>yylval</CODE> and <CODE>yylloc</CODE> may be used. The data types for +<CODE>yylval</CODE> and <CODE>yylloc</CODE>, (<CODE>YYSTYPE</CODE> and <CODE>YYLTYPE</CODE>, +are typically defined in a header file, included in section 1 of the +<CODE>flex</CODE> input file. If <CODE>%option bison-bridge</CODE> is +specified, <CODE>flex</CODE> provides support for the functions +<CODE>yyget_lval</CODE>, <CODE>yyset_lval</CODE>, <CODE>yyget_lloc</CODE>, and +<CODE>yyset_lloc</CODE>, defined below, and the corresponding macros +<CODE>yylval</CODE> and <CODE>yylloc</CODE>, for use within actions. + + +<P> +<DL> +<DT><U>Function:</U> YYSTYPE* <B>yyget_lval</B> <I>( yyscan_t scanner )</I> +<DD><A NAME="IDX471"></A> +</DL> +<DL> +<DT><U>Function:</U> YYLTYPE* <B>yyget_lloc</B> <I>( yyscan_t scanner )</I> +<DD><A NAME="IDX472"></A> +</DL> + + +<P> +<DL> +<DT><U>Function:</U> void <B>yyset_lval</B> <I>( YYSTYPE* lvalp, yyscan_t scanner )</I> +<DD><A NAME="IDX473"></A> +</DL> +<DL> +<DT><U>Function:</U> void <B>yyset_lloc</B> <I>( YYLTYPE* llocp, yyscan_t scanner )</I> +<DD><A NAME="IDX474"></A> +</DL> + + +<P> +Where yyscan_t is defined in the reentrant scanner <A NAME="DOCF6" HREF="flex_foot.html#FOOT6">(6)</A>. Accordingly, the declaration of +yylex becomes one of the following: + + +<P> +<A NAME="IDX475"></A> + +<PRE> +@verbatim + int yylex ( YYSTYPE * lvalp, yyscan_t scanner ); + int yylex ( YYSTYPE * lvalp, YYLTYPE * llocp, yyscan_t scanner ); +</PRE> + +<P> +Note that the macros <CODE>yylval</CODE> and <CODE>yylloc</CODE> evaluate to +pointers. Support for <CODE>yylloc</CODE> is optional in <CODE>bison</CODE>, so it +is optional in <CODE>flex</CODE> as well. This support is automatically +handled by <CODE>flex</CODE>. Specifically, support for <CODE>yyloc</CODE> is only +present in a <CODE>flex</CODE> scanner if the preprocessor symbol +<CODE>YYLTYPE</CODE> is defined. The following is an example of a <CODE>flex</CODE> +scanner that is compatible with <CODE>bison</CODE>. + + +<P> +<A NAME="IDX476"></A> + +<PRE> +@verbatim + /* Scanner for "C" assignment statements... sort of. */ + %{ + #include "y.tab.h" /* Generated by bison. */ + %} + + %option reentrant-bison + % + + [[:digit:]]+ { yylval->num = atoi(yytext); return NUMBER;} + [[:alnum:]]+ { yylval->str = strdup(yytext); return STRING;} + "="|";" { return yytext[0];} + . {} + % +</PRE> + +<P> +As you can see, there really is no magic here. We just use +<CODE>yylval</CODE> as we would any other variable. The data type of +<CODE>yylval</CODE> is generated by <CODE>bison</CODE>, and included in the file +<TT>`y.tab.h'</TT>. Here is the corresponding <CODE>bison</CODE> parser: + + +<P> +<A NAME="IDX477"></A> + +<PRE> +@verbatim + /* Parser to convert "C" assignments to lisp. */ + %{ + /* Pass the argument to yyparse through to yylex. */ + #define YYPARSE_PARAM scanner + #define YYLEX_PARAM scanner + %} + %pure_parser + %union { + int num; + char* str; + } + %token <str> STRING + %token <num> NUMBER + %% + assignment: + STRING '=' NUMBER ';' { + printf( "(setf %s %d)", $1, $3 ); + } + ; +</PRE> + + + +<H1><A NAME="SEC157" HREF="flex_toc.html#TOC157">Indices</A></H1> + + + +<H2><A NAME="SEC158" HREF="flex_toc.html#TOC158">Concept Index</A></H2> + +<P> Jump to: <A HREF="#cindex_$">$</A> - <A HREF="#cindex_%">%</A> - +<A HREF="#cindex_<"><</A> +- <A HREF="#cindex_[">[</A> - <A HREF="#cindex_^">^</A> @@ -6183,6 +9004,8 @@ - <A HREF="#cindex_f">f</A> - +<A HREF="#cindex_g">g</A> +- <A HREF="#cindex_h">h</A> - <A HREF="#cindex_i">i</A> @@ -6215,260 +9038,366 @@ <P> <H2><A NAME="cindex_$">$</A></H2> <DIR> -<LI><A HREF="flex.html#IDX303">$ -- see EOL</A> +<LI><A HREF="flex.html#IDX74">$ as normal character in patterns</A> </DIR> <H2><A NAME="cindex_%">%</A></H2> <DIR> -<LI><A HREF="flex.html#IDX65">%array, use of</A> -<LI><A HREF="flex.html#IDX68">%array, with C++</A> -<LI><A HREF="flex.html#IDX98">%pointer, caveat with unput()</A> -<LI><A HREF="flex.html#IDX66">%pointer, use of</A> -<LI><A HREF="flex.html#IDX15">%{ and %}, in Definitions Section</A> -<LI><A HREF="flex.html#IDX73">%{ and %}, in Rules Section</A> +<LI><A HREF="flex.html#IDX93">%array, advantages of</A> +<LI><A HREF="flex.html#IDX90">%array, use of</A> +<LI><A HREF="flex.html#IDX94">%array, with C++</A> +<LI><A HREF="flex.html#IDX124">%pointer, caveat with unput()</A> +<LI><A HREF="flex.html#IDX91">%pointer, use of</A> +<LI><A HREF="flex.html#IDX24">%{ and %}, in Definitions Section</A> +<LI><A HREF="flex.html#IDX99">%{ and %}, in Rules Section</A> +</DIR> +<H2><A NAME="cindex_<"><</A></H2> +<DIR> +<LI><A HREF="flex.html#IDX199"><<EOF>>, use of</A> </DIR> <H2><A NAME="cindex_[">[</A></H2> <DIR> -<LI><A HREF="flex.html#IDX33">[] in patterns</A> +<LI><A HREF="flex.html#IDX39">[] in patterns</A> </DIR> <H2><A NAME="cindex_^">^</A></H2> <DIR> -<LI><A HREF="flex.html#IDX301">^ -- see BOL</A> +<LI><A HREF="flex.html#IDX73">^ as non-special character in patterns</A> </DIR> <H2><A NAME="cindex_a">a</A></H2> <DIR> -<LI><A HREF="flex.html#IDX75">actions, embedded C strings</A> -<LI><A HREF="flex.html#IDX69">actions, explanation</A> -<LI><A HREF="flex.html#IDX183">actions, redefining YY_BREAK</A> -<LI><A HREF="flex.html#IDX74">actions, use of { and }</A> -<LI><A HREF="flex.html#IDX308">allocating memory see memory</A> -<LI><A HREF="flex.html#IDX201">arguments, command-line</A> -<LI><A HREF="flex.html#IDX187">array, default size for yytext</A> +<LI><A HREF="flex.html#IDX402">accessor functions, use of</A> +<LI><A HREF="flex.html#IDX101">actions, embedded C strings</A> +<LI><A HREF="flex.html#IDX95">actions, explanation</A> +<LI><A HREF="flex.html#IDX209">actions, redefining YY_BREAK</A> +<LI><A HREF="flex.html#IDX100">actions, use of { and }</A> +<LI><A HREF="flex.html#IDX18">aliases, how to define</A> +<LI><A HREF="flex.html#IDX227">arguments, command-line</A> +<LI><A HREF="flex.html#IDX213">array, default size for yytext</A> </DIR> <H2><A NAME="cindex_b">b</A></H2> <DIR> -<LI><A HREF="flex.html#IDX208">backing up, example of eliminating</A> -<LI><A HREF="flex.html#IDX83">BEGIN</A> -<LI><A HREF="flex.html#IDX130">BEGIN, explanation</A> -<LI><A HREF="flex.html#IDX300">beginning of line -- see BOL</A> -<LI><A HREF="flex.html#IDX310">bison, see also yacc</A> -<LI><A HREF="flex.html#IDX261">bison, with reentrant</A> -<LI><A HREF="flex.html#IDX56">BOL, ^ as normal character</A> -<LI><A HREF="flex.html#IDX181">BOL, checking the BOL flag</A> -<LI><A HREF="flex.html#IDX179">BOL, setting it</A> -<LI><A HREF="flex.html#IDX42">BOL, syntax of</A> -<LI><A HREF="flex.html#IDX296">bugs, reporting</A> +<LI><A HREF="flex.html#IDX356">backing up, eliminating</A> +<LI><A HREF="flex.html#IDX358">backing up, eliminating by adding error rules</A> +<LI><A HREF="flex.html#IDX359">backing up, eliminating with catch-all rule</A> +<LI><A HREF="flex.html#IDX355">backing up, example of eliminating</A> +<LI><A HREF="flex.html#IDX109">BEGIN</A> +<LI><A HREF="flex.html#IDX156">BEGIN, explanation</A> +<LI><A HREF="flex.html#IDX54">beginning of line, in patterns</A> +<LI><A HREF="flex.html#IDX466">bison, bridging with flex</A> +<LI><A HREF="flex.html#IDX477">bison, parser</A> +<LI><A HREF="flex.html#IDX476">bison, scanner to be called from bison</A> +<LI><A HREF="flex.html#IDX207">BOL, checking the BOL flag</A> +<LI><A HREF="flex.html#IDX55">BOL, in patterns</A> +<LI><A HREF="flex.html#IDX205">BOL, setting it</A> +<LI><A HREF="flex.html#IDX45">braces in patterns</A> +<LI><A HREF="flex.html#IDX3">bugs, reporting</A> </DIR> <H2><A NAME="cindex_c">c</A></H2> <DIR> -<LI><A HREF="flex.html#IDX218">C++</A> -<LI><A HREF="flex.html#IDX189">C++ and %array</A> -<LI><A HREF="flex.html#IDX236">C++, multiple different scanners</A> -<LI><A HREF="flex.html#IDX53">case-insensitive, effect on character classes</A> -<LI><A HREF="flex.html#IDX49">character classes in patterns</A> -<LI><A HREF="flex.html#IDX30">character classes in patterns, syntax of</A> -<LI><A HREF="flex.html#IDX51">character classes, equivalence of</A> -<LI><A HREF="flex.html#IDX158">clearing an input buffer</A> -<LI><A HREF="flex.html#IDX199">command-line options</A> -<LI><A HREF="flex.html#IDX103">comments, example of discarding</A> -<LI><A HREF="flex.html#IDX135">comments, example of scanning C comments</A> -<LI><A HREF="flex.html#IDX24">comments, syntax</A> -<LI><A HREF="flex.html#IDX25">comments, valid uses of</A> -<LI><A HREF="flex.html#IDX77">commments, in actions</A> -<LI><A HREF="flex.html#IDX294">copyright of flex</A> +<LI><A HREF="flex.html#IDX26">C code in flex input</A> +<LI><A HREF="flex.html#IDX367">C++</A> +<LI><A HREF="flex.html#IDX215">C++ and %array</A> +<LI><A HREF="flex.html#IDX462">C++ I/O, customizing</A> +<LI><A HREF="flex.html#IDX388">C++ scanners, including multiple scanners</A> +<LI><A HREF="flex.html#IDX384">C++ scanners, use of</A> +<LI><A HREF="flex.html#IDX365">c++, experimental form of scanner class</A> +<LI><A HREF="flex.html#IDX385">C++, multiple different scanners</A> +<LI><A HREF="flex.html#IDX69">case-insensitive, effect on character classes</A> +<LI><A HREF="flex.html#IDX65">character classes in patterns</A> +<LI><A HREF="flex.html#IDX40">character classes in patterns, syntax of</A> +<LI><A HREF="flex.html#IDX67">character classes, equivalence of</A> +<LI><A HREF="flex.html#IDX184">clearing an input buffer</A> +<LI><A HREF="flex.html#IDX225">command-line options</A> +<LI><A HREF="flex.html#IDX23">comments in flex input</A> +<LI><A HREF="flex.html#IDX34">comments in the input</A> +<LI><A HREF="flex.html#IDX129">comments, example of discarding</A> +<LI><A HREF="flex.html#IDX161">comments, example of scanning C comments</A> +<LI><A HREF="flex.html#IDX32">comments, in rules section</A> +<LI><A HREF="flex.html#IDX31">comments, syntax of</A> +<LI><A HREF="flex.html#IDX33">comments, valid uses of</A> +<LI><A HREF="flex.html#IDX103">commments, in actions</A> +<LI><A HREF="flex.html#IDX98">compressing whitespace</A> +<LI><A HREF="flex.html#IDX52">concatenation, in patterns</A> +<LI><A HREF="flex.html#IDX1">copyright of flex</A> +<LI><A HREF="flex.html#IDX9">counting characters and lines</A> +<LI><A HREF="flex.html#IDX461">customizing I/O in C++ scanners</A> </DIR> <H2><A NAME="cindex_d">d</A></H2> <DIR> -<LI><A HREF="flex.html#IDX2">default rule</A> -<LI><A HREF="flex.html#IDX62">default rule, explanation</A> -<LI><A HREF="flex.html#IDX11">Definitions Sections</A> -<LI><A HREF="flex.html#IDX295">distributing flex</A> +<LI><A HREF="flex.html#IDX7">default rule</A>, <A HREF="flex.html#IDX87">default rule</A> +<LI><A HREF="flex.html#IDX21">defining pattern aliases</A> +<LI><A HREF="flex.html#IDX17">Definitions, in flex input</A> +<LI><A HREF="flex.html#IDX96">deleting lines from input</A> +<LI><A HREF="flex.html#IDX130">discarding C comments</A> +<LI><A HREF="flex.html#IDX2">distributing flex</A> </DIR> <H2><A NAME="cindex_e">e</A></H2> <DIR> -<LI><A HREF="flex.html#IDX82">ECHO, explanation</A> -<LI><A HREF="flex.html#IDX16">embedding C code with %{ and %}</A> -<LI><A HREF="flex.html#IDX304">end of file -- see EOF</A> -<LI><A HREF="flex.html#IDX302">end of line -- see EOL</A> -<LI><A HREF="flex.html#IDX116">EOF and yyrestart()</A> -<LI><A HREF="flex.html#IDX45">EOF in patterns, syntax of</A> -<LI><A HREF="flex.html#IDX163">EOF, example using multiple input buffers</A> -<LI><A HREF="flex.html#IDX171">EOF, explanation</A> -<LI><A HREF="flex.html#IDX101">EOF, pushing back</A> -<LI><A HREF="flex.html#IDX43">EOL in patterns, syntax of</A> -<LI><A HREF="flex.html#IDX57">EOL, $ as normal character</A> -<LI><A HREF="flex.html#IDX54">EOL, in negated character classes</A> -<LI><A HREF="flex.html#IDX289">error reporting, diagnostic messages</A> -<LI><A HREF="flex.html#IDX233">error reporting, in C++</A> -<LI><A HREF="flex.html#IDX210">error rules, to eliminate backing up</A> -<LI><A HREF="flex.html#IDX39">escape sequences in patterns, syntax of</A> -<LI><A HREF="flex.html#IDX109">exiting with yyterminate()</A> +<LI><A HREF="flex.html#IDX108">ECHO, explanation</A> +<LI><A HREF="flex.html#IDX25">embedding C code in flex input</A> +<LI><A HREF="flex.html#IDX60">end of file, in patterns</A> +<LI><A HREF="flex.html#IDX70">end of line, in negated character classes</A> +<LI><A HREF="flex.html#IDX56">end of line, in patterns</A> +<LI><A HREF="flex.html#IDX142">EOF and yyrestart()</A> +<LI><A HREF="flex.html#IDX61">EOF in patterns, syntax of</A> +<LI><A HREF="flex.html#IDX189">EOF, example using multiple input buffers</A> +<LI><A HREF="flex.html#IDX197">EOF, explanation</A> +<LI><A HREF="flex.html#IDX127">EOF, pushing back</A> +<LI><A HREF="flex.html#IDX71">EOL, in negated character classes</A> +<LI><A HREF="flex.html#IDX57">EOL, in patterns</A> +<LI><A HREF="flex.html#IDX425">error messages, end of buffer missed</A> +<LI><A HREF="flex.html#IDX452">error reporting, diagnostic messages</A> +<LI><A HREF="flex.html#IDX382">error reporting, in C++</A> +<LI><A HREF="flex.html#IDX357">error rules, to eliminate backing up</A> +<LI><A HREF="flex.html#IDX49">escape sequences in patterns, syntax of</A> +<LI><A HREF="flex.html#IDX135">exiting with yyterminate()</A> +<LI><A HREF="flex.html#IDX366">experimental form of c++ scanner class</A> +<LI><A HREF="flex.html#IDX170">extended scope of start conditions</A> </DIR> <H2><A NAME="cindex_f">f</A></H2> <DIR> -<LI><A HREF="flex.html#IDX6">file format</A> -<LI><A HREF="flex.html#IDX1">flex, introduction</A> -<LI><A HREF="flex.html#IDX159">flushing an input buffer</A> -<LI><A HREF="flex.html#IDX106">flushing the internal buffer</A> -<LI><A HREF="flex.html#IDX5">format of the input</A> -<LI><A HREF="flex.html#IDX9">format, Definitions Section</A> -<LI><A HREF="flex.html#IDX18">format, Rules Section</A> -<LI><A HREF="flex.html#IDX21">format, User Code Section</A> -<LI><A HREF="flex.html#IDX307">freeing memory -- see memory</A> +<LI><A HREF="flex.html#IDX13">file format</A> +<LI><A HREF="flex.html#IDX451">file format, serialized tables</A> +<LI><A HREF="flex.html#IDX185">flushing an input buffer</A> +<LI><A HREF="flex.html#IDX132">flushing the internal buffer</A> +<LI><A HREF="flex.html#IDX11">format of flex input</A> +<LI><A HREF="flex.html#IDX15">format of input file</A> +<LI><A HREF="flex.html#IDX446">freeing tables</A> +</DIR> +<H2><A NAME="cindex_g">g</A></H2> +<DIR> +<LI><A HREF="flex.html#IDX166">getting current start state with YY_START</A> </DIR> <H2><A NAME="cindex_h">h</A></H2> <DIR> -<LI><A HREF="flex.html#IDX110">halting with yyterminate()</A> -<LI><A HREF="flex.html#IDX238">header files, with C++</A> +<LI><A HREF="flex.html#IDX136">halting with yyterminate()</A> +<LI><A HREF="flex.html#IDX190">handling include files with multiple input buffers</A> +<LI><A HREF="flex.html#IDX387">header files, with C++</A> </DIR> <H2><A NAME="cindex_i">i</A></H2> <DIR> -<LI><A HREF="flex.html#IDX237">include files, with C++</A> -<LI><A HREF="flex.html#IDX17">including C code with %{ and %}</A> -<LI><A HREF="flex.html#IDX105">input(), and C++</A> -<LI><A HREF="flex.html#IDX102">input(), explanation</A> +<LI><A HREF="flex.html#IDX386">include files, with C++</A> +<LI><A HREF="flex.html#IDX16">input file, Definitions section</A> +<LI><A HREF="flex.html#IDX27">input file, Rules Section</A> +<LI><A HREF="flex.html#IDX29">input file, user code Section</A> +<LI><A HREF="flex.html#IDX131">input(), and C++</A> +<LI><A HREF="flex.html#IDX128">input(), explanation</A> +<LI><A HREF="flex.html#IDX12">input, format of</A> +<LI><A HREF="flex.html#IDX79">input, matching</A> </DIR> <H2><A NAME="cindex_k">k</A></H2> <DIR> -<LI><A HREF="flex.html#IDX215">keywords, for performance</A> +<LI><A HREF="flex.html#IDX362">keywords, for performance</A> </DIR> <H2><A NAME="cindex_l">l</A></H2> <DIR> -<LI><A HREF="flex.html#IDX283">lex (traditional) and POSIX</A> -<LI><A HREF="flex.html#IDX292">limitations of flex</A> -<LI><A HREF="flex.html#IDX37">literal text in patterns, syntax of</A> +<LI><A HREF="flex.html#IDX424">lex (traditional) and POSIX</A> +<LI><A HREF="flex.html#IDX458">LexerInput, overriding</A> +<LI><A HREF="flex.html#IDX457">LexerOutput, overriding</A> +<LI><A HREF="flex.html#IDX455">limitations of flex</A> +<LI><A HREF="flex.html#IDX47">literal text in patterns, syntax of</A> +<LI><A HREF="flex.html#IDX444">loading tables at runtime</A> </DIR> <H2><A NAME="cindex_m">m</A></H2> <DIR> -<LI><A HREF="flex.html#IDX306">macros, see preprocessor macros</A> -<LI><A HREF="flex.html#IDX297">Makefile, syntax</A> -<LI><A HREF="flex.html#IDX309">malloc -- see memory</A> -<LI><A HREF="flex.html#IDX219">member functions in C++</A> -<LI><A HREF="flex.html#IDX152">memory, allocating input buffers</A> -<LI><A HREF="flex.html#IDX248">memory, considerations for reentrant scanners</A> -<LI><A HREF="flex.html#IDX156">memory, deleting input buffers</A> -<LI><A HREF="flex.html#IDX150">memory, for start condition stacks</A> -<LI><A HREF="flex.html#IDX220">methods</A> -<LI><A HREF="flex.html#IDX151">multiple input streams</A> +<LI><A HREF="flex.html#IDX464">Makefile, example of implicit rules</A> +<LI><A HREF="flex.html#IDX465">Makefile, explicit example</A> +<LI><A HREF="flex.html#IDX463">Makefile, syntax</A> +<LI><A HREF="flex.html#IDX168">matching C-style double-quoted strings</A> +<LI><A HREF="flex.html#IDX81">matching, and trailing context</A> +<LI><A HREF="flex.html#IDX82">matching, length of</A> +<LI><A HREF="flex.html#IDX83">matching, multiple matches</A> +<LI><A HREF="flex.html#IDX368">member functions, C++</A> +<LI><A HREF="flex.html#IDX431">memory management</A> +<LI><A HREF="flex.html#IDX178">memory, allocating input buffers</A> +<LI><A HREF="flex.html#IDX397">memory, considerations for reentrant scanners</A> +<LI><A HREF="flex.html#IDX182">memory, deleting input buffers</A> +<LI><A HREF="flex.html#IDX176">memory, for start condition stacks</A> +<LI><A HREF="flex.html#IDX439">memory, serialized tables</A>, <A HREF="flex.html#IDX447">memory, serialized tables</A> +<LI><A HREF="flex.html#IDX369">methods, c++</A> +<LI><A HREF="flex.html#IDX88">minimal scanner</A> +<LI><A HREF="flex.html#IDX177">multiple input streams</A> </DIR> <H2><A NAME="cindex_n">n</A></H2> <DIR> -<LI><A HREF="flex.html#IDX35">negating ranges in patterns</A> -<LI><A HREF="flex.html#IDX40">NULL character in patterns, syntax of</A> +<LI><A HREF="flex.html#IDX427">name definitions, not POSIX</A> +<LI><A HREF="flex.html#IDX44">negating ranges in patterns</A> +<LI><A HREF="flex.html#IDX58">newline, matching in patterns</A> +<LI><A HREF="flex.html#IDX430">non-POSIX features of flex</A> +<LI><A HREF="flex.html#IDX50">NULL character in patterns, syntax of</A> </DIR> <H2><A NAME="cindex_o">o</A></H2> <DIR> -<LI><A HREF="flex.html#IDX200">options, command-line</A> +<LI><A HREF="flex.html#IDX51">octal characters in patterns</A> +<LI><A HREF="flex.html#IDX226">options, command-line</A> +<LI><A HREF="flex.html#IDX460">overriding LexerInput</A> +<LI><A HREF="flex.html#IDX459">overriding LexerOutput</A> +<LI><A HREF="flex.html#IDX436">overriding the memory routines</A> </DIR> <H2><A NAME="cindex_p">p</A></H2> <DIR> -<LI><A HREF="flex.html#IDX36">pattern aliases, expansion of</A> -<LI><A HREF="flex.html#IDX27">Patterns</A> -<LI><A HREF="flex.html#IDX12">patterns aliases, how to define</A> -<LI><A HREF="flex.html#IDX61">patterns, how the input is matched</A> -<LI><A HREF="flex.html#IDX46">patterns, precedence of operators</A> -<LI><A HREF="flex.html#IDX28">patterns, syntax</A> -<LI><A HREF="flex.html#IDX206">patterns, tuning for performance</A> -<LI><A HREF="flex.html#IDX207">performance, backing up</A> -<LI><A HREF="flex.html#IDX202">performance, considerations</A> -<LI><A HREF="flex.html#IDX216">performance, using keywords</A> -<LI><A HREF="flex.html#IDX282">POSIX and lex</A> -<LI><A HREF="flex.html#IDX31">POSIX, character classes in patterns, syntax of</A> -<LI><A HREF="flex.html#IDX288">POSIX, non-POSIX features of flex</A> -<LI><A HREF="flex.html#IDX81">preprocessor macros, for use in actions</A> -<LI><A HREF="flex.html#IDX96">pushing back characters with unput</A> -<LI><A HREF="flex.html#IDX93">pushing back characters with yyless</A> -<LI><A HREF="flex.html#IDX100">pushing back EOF</A> +<LI><A HREF="flex.html#IDX10">Pascal-like language</A> +<LI><A HREF="flex.html#IDX20">pattern aliases, defining</A> +<LI><A HREF="flex.html#IDX46">pattern aliases, expansion of</A> +<LI><A HREF="flex.html#IDX19">pattern aliases, how to define</A> +<LI><A HREF="flex.html#IDX22">pattern aliases, use of</A> +<LI><A HREF="flex.html#IDX428">patterns and actions on different lines</A> +<LI><A HREF="flex.html#IDX68">patterns, character class equivalence</A> +<LI><A HREF="flex.html#IDX77">patterns, end of line</A> +<LI><A HREF="flex.html#IDX63">patterns, grouping and precedence</A> +<LI><A HREF="flex.html#IDX35">patterns, in rules section</A> +<LI><A HREF="flex.html#IDX75">patterns, invalid trailing context</A> +<LI><A HREF="flex.html#IDX78">patterns, matching</A> +<LI><A HREF="flex.html#IDX62">patterns, precedence of operators</A> +<LI><A HREF="flex.html#IDX64">patterns, repetitions with grouping</A> +<LI><A HREF="flex.html#IDX76">patterns, special characters treated as non-special</A> +<LI><A HREF="flex.html#IDX37">patterns, syntax</A>, <A HREF="flex.html#IDX38">patterns, syntax</A> +<LI><A HREF="flex.html#IDX353">patterns, tuning for performance</A> +<LI><A HREF="flex.html#IDX66">patterns, valid character classes</A> +<LI><A HREF="flex.html#IDX361">performance optimization, matching longer tokens</A> +<LI><A HREF="flex.html#IDX364">performance optimization, recognizing keywords</A> +<LI><A HREF="flex.html#IDX354">performance, backing up</A> +<LI><A HREF="flex.html#IDX349">performance, considerations</A> +<LI><A HREF="flex.html#IDX363">performance, using keywords</A> +<LI><A HREF="flex.html#IDX423">POSIX and lex</A> +<LI><A HREF="flex.html#IDX429">POSIX comp;compliance</A> +<LI><A HREF="flex.html#IDX41">POSIX, character classes in patterns, syntax of</A> +<LI><A HREF="flex.html#IDX107">preprocessor macros, for use in actions</A> +<LI><A HREF="flex.html#IDX122">pushing back characters with unput</A> +<LI><A HREF="flex.html#IDX119">pushing back characters with yyless</A> +<LI><A HREF="flex.html#IDX126">pushing back EOF</A> </DIR> <H2><A NAME="cindex_r">r</A></H2> <DIR> -<LI><A HREF="flex.html#IDX32">ranges in patterns</A> -<LI><A HREF="flex.html#IDX34">ranges in patterns, negating</A> -<LI><A HREF="flex.html#IDX247">reentrant, accessing flex variables</A> -<LI><A HREF="flex.html#IDX252">reentrant, accessor functions</A> -<LI><A HREF="flex.html#IDX243">reentrant, API explanation</A> -<LI><A HREF="flex.html#IDX245">reentrant, calling functions</A> -<LI><A HREF="flex.html#IDX244">reentrant, example of</A> -<LI><A HREF="flex.html#IDX240">reentrant, explanation</A> -<LI><A HREF="flex.html#IDX254">reentrant, extra data</A> -<LI><A HREF="flex.html#IDX249">reentrant, initialization</A> -<LI><A HREF="flex.html#IDX305">regular expressions -- see Patterns</A> -<LI><A HREF="flex.html#IDX85">REJECT, example</A> -<LI><A HREF="flex.html#IDX84">REJECT, explanation</A> -<LI><A HREF="flex.html#IDX203">REJECT, performance costs</A> -<LI><A HREF="flex.html#IDX117">returning from within an action</A> -<LI><A HREF="flex.html#IDX20">Rules Section</A> +<LI><A HREF="flex.html#IDX42">ranges in patterns</A> +<LI><A HREF="flex.html#IDX43">ranges in patterns, negating</A> +<LI><A HREF="flex.html#IDX162">recognizing C comments</A> +<LI><A HREF="flex.html#IDX390">reentrant scanners, multiple interleaved scanners</A> +<LI><A HREF="flex.html#IDX391">reentrant scanners, recursive invocation</A> +<LI><A HREF="flex.html#IDX396">reentrant, accessing flex variables</A> +<LI><A HREF="flex.html#IDX401">reentrant, accessor functions</A> +<LI><A HREF="flex.html#IDX392">reentrant, API explanation</A> +<LI><A HREF="flex.html#IDX394">reentrant, calling functions</A> +<LI><A HREF="flex.html#IDX393">reentrant, example of</A> +<LI><A HREF="flex.html#IDX389">reentrant, explanation</A> +<LI><A HREF="flex.html#IDX403">reentrant, extra data</A> +<LI><A HREF="flex.html#IDX398">reentrant, initialization</A> +<LI><A HREF="flex.html#IDX36">regular expressions, in patterns</A> +<LI><A HREF="flex.html#IDX112">REJECT</A> +<LI><A HREF="flex.html#IDX113">REJECT, calling multiple times</A> +<LI><A HREF="flex.html#IDX111">REJECT, example</A> +<LI><A HREF="flex.html#IDX110">REJECT, explanation</A> +<LI><A HREF="flex.html#IDX350">REJECT, performance costs</A> +<LI><A HREF="flex.html#IDX4">reporting bugs</A> +<LI><A HREF="flex.html#IDX426">restarting the scanner</A> +<LI><A HREF="flex.html#IDX143">returning from within an action</A> +<LI><A HREF="flex.html#IDX8">rules, default</A> +<LI><A HREF="flex.html#IDX28">rules, in flex input</A> </DIR> <H2><A NAME="cindex_s">s</A></H2> <DIR> -<LI><A HREF="flex.html#IDX7">sections of the input</A> -<LI><A HREF="flex.html#IDX10">sections, Definitions Section</A> -<LI><A HREF="flex.html#IDX19">sections, format of Rules Section</A> -<LI><A HREF="flex.html#IDX22">sections, User Code Section</A> -<LI><A HREF="flex.html#IDX145">stacks, routines for manipulating</A> -<LI><A HREF="flex.html#IDX143">start condition, applying to multiple patterns</A> -<LI><A HREF="flex.html#IDX44">start conditions in patterns, syntax of</A> -<LI><A HREF="flex.html#IDX121">start conditions, explanation</A> -<LI><A HREF="flex.html#IDX124">start conditions, inclusive v.s. exclusive</A> -<LI><A HREF="flex.html#IDX137">start conditions, integer values</A> -<LI><A HREF="flex.html#IDX127">start conditions, special wildcard condition</A> -<LI><A HREF="flex.html#IDX146">start conditions, use of a stack</A> -<LI><A HREF="flex.html#IDX115">stdin, default for yyin</A> -<LI><A HREF="flex.html#IDX76">strings, in actions</A> -<LI><A HREF="flex.html#IDX165">strings, scanning strings instead of files</A> +<LI><A HREF="flex.html#IDX5">scanner, definition of</A> +<LI><A HREF="flex.html#IDX14">sections of flex input</A> +<LI><A HREF="flex.html#IDX438">serialization</A> +<LI><A HREF="flex.html#IDX441">serialization of tables</A> +<LI><A HREF="flex.html#IDX442">serialized tables, multiple scanners</A> +<LI><A HREF="flex.html#IDX171">stacks, routines for manipulating</A> +<LI><A HREF="flex.html#IDX169">start condition, applying to multiple patterns</A> +<LI><A HREF="flex.html#IDX148">start conditions, basic</A> +<LI><A HREF="flex.html#IDX155">start conditions, behavior of default rule</A> +<LI><A HREF="flex.html#IDX152">start conditions, exclusive</A> +<LI><A HREF="flex.html#IDX147">start conditions, explanation</A> +<LI><A HREF="flex.html#IDX160">start conditions, for different interpretations of same input</A> +<LI><A HREF="flex.html#IDX59">start conditions, in patterns</A> +<LI><A HREF="flex.html#IDX151">start conditions, inclusive</A> +<LI><A HREF="flex.html#IDX150">start conditions, inclusive v.s. exclusive</A> +<LI><A HREF="flex.html#IDX163">start conditions, integer values</A> +<LI><A HREF="flex.html#IDX149">start conditions, multiple</A> +<LI><A HREF="flex.html#IDX153">start conditions, special wildcard condition</A> +<LI><A HREF="flex.html#IDX172">start conditions, use of a stack</A> +<LI><A HREF="flex.html#IDX154">start conditions, use of wildcard condition (<*>)</A> +<LI><A HREF="flex.html#IDX159">start conditions, using BEGIN</A> +<LI><A HREF="flex.html#IDX141">stdin, default for yyin</A> +<LI><A HREF="flex.html#IDX102">strings, in actions</A> +<LI><A HREF="flex.html#IDX191">strings, scanning strings instead of files</A> </DIR> <H2><A NAME="cindex_t">t</A></H2> <DIR> -<LI><A HREF="flex.html#IDX108">terminating with yyterminate()</A> -<LI><A HREF="flex.html#IDX41">trailing context in patterns, syntax of</A> -<LI><A HREF="flex.html#IDX55">trailing context, limits of</A> -<LI><A HREF="flex.html#IDX205">trailing context, performance costs</A> +<LI><A HREF="flex.html#IDX440">tables, creating serialized</A> +<LI><A HREF="flex.html#IDX450">tables, file format</A> +<LI><A HREF="flex.html#IDX445">tables, freeing</A> +<LI><A HREF="flex.html#IDX443">tables, loading and unloading</A> +<LI><A HREF="flex.html#IDX134">terminating with yyterminate()</A> +<LI><A HREF="flex.html#IDX84">token</A> +<LI><A HREF="flex.html#IDX53">trailing context, in patterns</A> +<LI><A HREF="flex.html#IDX72">trailing context, limits of</A> +<LI><A HREF="flex.html#IDX80">trailing context, matching</A> +<LI><A HREF="flex.html#IDX352">trailing context, performance costs</A> +<LI><A HREF="flex.html#IDX360">trailing context, variable length</A> </DIR> <H2><A NAME="cindex_u">u</A></H2> <DIR> -<LI><A HREF="flex.html#IDX99">unput(), caveat with %pointer</A> -<LI><A HREF="flex.html#IDX95">unput(), explanation</A> -<LI><A HREF="flex.html#IDX23">User Code Section</A> +<LI><A HREF="flex.html#IDX123">unput() to push back characters</A> +<LI><A HREF="flex.html#IDX125">unput(), caveat with %pointer</A> +<LI><A HREF="flex.html#IDX121">unput(), explanation</A> +<LI><A HREF="flex.html#IDX30">user code, in flex input</A> +<LI><A HREF="flex.html#IDX6">username expansion</A> +<LI><A HREF="flex.html#IDX164">using integer values of start condition names</A> </DIR> <H2><A NAME="cindex_v">v</A></H2> <DIR> -<LI><A HREF="flex.html#IDX38">verbatim text in patterns, syntax of</A> +<LI><A HREF="flex.html#IDX48">verbatim text in patterns, syntax of</A> </DIR> <H2><A NAME="cindex_w">w</A></H2> <DIR> -<LI><A HREF="flex.html#IDX290">warnings, diagnostic messages</A> -<LI><A HREF="flex.html#IDX71">whitespace, compressing, example</A> +<LI><A HREF="flex.html#IDX456">warning, dangerous trailing context</A> +<LI><A HREF="flex.html#IDX454">warning, rule cannot be matched</A> +<LI><A HREF="flex.html#IDX453">warnings, diagnostic messages</A> +<LI><A HREF="flex.html#IDX97">whitespace, compressing, example</A> </DIR> <H2><A NAME="cindex_y">y</A></H2> <DIR> -<LI><A HREF="flex.html#IDX196">yacc, interface</A> -<LI><A HREF="flex.html#IDX162">YY_CURRENT_BUFFER, and multiple buffers</A> -<LI><A HREF="flex.html#IDX118">YY_INPUT, overriding</A> -<LI><A HREF="flex.html#IDX139">YY_START, example</A> -<LI><A HREF="flex.html#IDX79">yyleng, modification of</A> -<LI><A HREF="flex.html#IDX92">yyless(), example</A> -<LI><A HREF="flex.html#IDX91">yyless(), explanation</A> -<LI><A HREF="flex.html#IDX112">yylex(), in generated scanner</A> -<LI><A HREF="flex.html#IDX113">yylex(), overriding</A> -<LI><A HREF="flex.html#IDX281">yylineno, in a reentrant scanner</A> -<LI><A HREF="flex.html#IDX204">yylineno, performance costs</A> -<LI><A HREF="flex.html#IDX89">yymore(), example</A> -<LI><A HREF="flex.html#IDX88">yymore(), explanation</A> -<LI><A HREF="flex.html#IDX80">yymore, caveat</A> -<LI><A HREF="flex.html#IDX107">yyterminate(), explanation</A> -<LI><A HREF="flex.html#IDX186">yytext, default array size</A> -<LI><A HREF="flex.html#IDX64">yytext, definition of</A> -<LI><A HREF="flex.html#IDX78">yytext, modification of</A> -<LI><A HREF="flex.html#IDX120">yywrap(), explanation</A> +<LI><A HREF="flex.html#IDX224">yacc interface</A> +<LI><A HREF="flex.html#IDX222">yacc, interface</A> +<LI><A HREF="flex.html#IDX188">YY_CURRENT_BUFFER, and multiple buffers</A> +<LI><A HREF="flex.html#IDX408">YY_EXTRA_TYPE, defining your own type</A> +<LI><A HREF="flex.html#IDX144">YY_INPUT, overriding</A> +<LI><A HREF="flex.html#IDX145">YY_INPUT, overriding the input mechanism</A> +<LI><A HREF="flex.html#IDX165">YY_START, example</A> +<LI><A HREF="flex.html#IDX201">YY_USER_ACTION to track each time a rule is matched</A> +<LI><A HREF="flex.html#IDX432">yyalloc, overriding</A> +<LI><A HREF="flex.html#IDX434">yyfree, overriding</A> +<LI><A HREF="flex.html#IDX86">yyleng</A> +<LI><A HREF="flex.html#IDX105">yyleng, modification of</A> +<LI><A HREF="flex.html#IDX120">yyless() to push back characters</A> +<LI><A HREF="flex.html#IDX118">yyless(), example</A> +<LI><A HREF="flex.html#IDX117">yyless(), explanation</A> +<LI><A HREF="flex.html#IDX138">yylex(), in generated scanner</A> +<LI><A HREF="flex.html#IDX139">yylex(), overriding</A> +<LI><A HREF="flex.html#IDX140">yylex, overriding the prototype</A> +<LI><A HREF="flex.html#IDX422">yylineno, in a reentrant scanner</A> +<LI><A HREF="flex.html#IDX351">yylineno, performance costs</A> +<LI><A HREF="flex.html#IDX116">yymore() to append token to previous token</A> +<LI><A HREF="flex.html#IDX115">yymore(), example</A> +<LI><A HREF="flex.html#IDX114">yymore(), explanation</A> +<LI><A HREF="flex.html#IDX106">yymore, caveat</A> +<LI><A HREF="flex.html#IDX433">yyrealloc, overriding</A> +<LI><A HREF="flex.html#IDX133">yyterminate(), explanation</A> +<LI><A HREF="flex.html#IDX85">yytext</A> +<LI><A HREF="flex.html#IDX212">yytext, default array size</A> +<LI><A HREF="flex.html#IDX437">yytext, memory considerations</A> +<LI><A HREF="flex.html#IDX104">yytext, modification of</A> +<LI><A HREF="flex.html#IDX89">yytext, two types of</A> +<LI><A HREF="flex.html#IDX146">yywrap(), explanation</A> </DIR> -<H2><A NAME="SEC83" HREF="flex_toc.html#TOC83">Index of Functions and Macros</A></H2> +<H2><A NAME="SEC159" HREF="flex_toc.html#TOC159">Index of Functions and Macros</A></H2> <P> This is an index of functions and preprocessor macros that look like functions. -For macros that expand to variables or constants, see section <A HREF="flex.html#SEC84">Index of Variables</A>. +For macros that expand to variables or constants, see section <A HREF="flex.html#SEC160">Index of Variables</A>. <P> @@ -6485,70 +9414,74 @@ <P> <H2><A NAME="findex_b">b</A></H2> <DIR> -<LI><A HREF="flex.html#IDX131">BEGIN</A> +<LI><A HREF="flex.html#IDX157">BEGIN</A> </DIR> <H2><A NAME="findex_d">d</A></H2> <DIR> -<LI><A HREF="flex.html#IDX225">debug (C++ only)</A> +<LI><A HREF="flex.html#IDX374">debug (C++ only)</A> </DIR> <H2><A NAME="findex_l">l</A></H2> <DIR> -<LI><A HREF="flex.html#IDX234">LexerError (C++ only)</A> -<LI><A HREF="flex.html#IDX231">LexerInput (C++ only)</A> -<LI><A HREF="flex.html#IDX232">LexerOutput (C++ only)</A> -<LI><A HREF="flex.html#IDX223">lineno (C++ only)</A> +<LI><A HREF="flex.html#IDX383">LexerError (C++ only)</A> +<LI><A HREF="flex.html#IDX380">LexerInput (C++ only)</A> +<LI><A HREF="flex.html#IDX381">LexerOutput (C++ only)</A> +<LI><A HREF="flex.html#IDX372">lineno (C++ only)</A> </DIR> <H2><A NAME="findex_s">s</A></H2> <DIR> -<LI><A HREF="flex.html#IDX224">set_debug (C++ only)</A> -<LI><A HREF="flex.html#IDX230">switch_streams (C++ only)</A> +<LI><A HREF="flex.html#IDX373">set_debug (C++ only)</A> +<LI><A HREF="flex.html#IDX379">switch_streams (C++ only)</A> </DIR> <H2><A NAME="findex_y">y</A></H2> <DIR> -<LI><A HREF="flex.html#IDX182">YY_AT_BOL</A> -<LI><A HREF="flex.html#IDX153">yy_create_buffer</A> -<LI><A HREF="flex.html#IDX157">yy_delete_buffer</A> -<LI><A HREF="flex.html#IDX160">yy_flush_buffer</A> -<LI><A HREF="flex.html#IDX161">yy_new_buffer</A> -<LI><A HREF="flex.html#IDX172">YY_NEW_FILE (now obsolete)</A> -<LI><A HREF="flex.html#IDX148">yy_pop_state</A> -<LI><A HREF="flex.html#IDX147">yy_push_state</A> -<LI><A HREF="flex.html#IDX169">yy_scan_buffer</A> -<LI><A HREF="flex.html#IDX167">yy_scan_bytes</A> -<LI><A HREF="flex.html#IDX166">yy_scan_string</A> -<LI><A HREF="flex.html#IDX180">yy_set_bol</A> -<LI><A HREF="flex.html#IDX178">yy_set_interactive</A> -<LI><A HREF="flex.html#IDX155">yy_switch_to_buffer</A> -<LI><A HREF="flex.html#IDX149">yy_top_state</A> -<LI><A HREF="flex.html#IDX228">yyFlexLexer constructor (C++ only)</A> -<LI><A HREF="flex.html#IDX257">yyget_extra</A> -<LI><A HREF="flex.html#IDX275">yyget_in</A> -<LI><A HREF="flex.html#IDX274">yyget_leng</A> -<LI><A HREF="flex.html#IDX277">yyget_lineno</A> -<LI><A HREF="flex.html#IDX267">yyget_lloc</A> -<LI><A HREF="flex.html#IDX266">yyget_lval</A> -<LI><A HREF="flex.html#IDX276">yyget_out</A> -<LI><A HREF="flex.html#IDX273">yyget_text</A> -<LI><A HREF="flex.html#IDX222">YYLeng (C++ only)</A> -<LI><A HREF="flex.html#IDX229">yylex (C++ version)</A> -<LI><A HREF="flex.html#IDX270">yylex (reentrant version)</A> -<LI><A HREF="flex.html#IDX251">yylex_destroy</A> -<LI><A HREF="flex.html#IDX250">yylex_init</A> -<LI><A HREF="flex.html#IDX192">yyrestart</A> -<LI><A HREF="flex.html#IDX258">yyset_extra</A> -<LI><A HREF="flex.html#IDX278">yyset_in</A> -<LI><A HREF="flex.html#IDX280">yyset_lineno</A> -<LI><A HREF="flex.html#IDX269">yyset_lloc</A> -<LI><A HREF="flex.html#IDX268">yyset_lval</A> -<LI><A HREF="flex.html#IDX279">yyset_out</A> -<LI><A HREF="flex.html#IDX111">yyterminate</A> -<LI><A HREF="flex.html#IDX221">YYText (C++ only)</A> +<LI><A HREF="flex.html#IDX208">YY_AT_BOL</A> +<LI><A HREF="flex.html#IDX179">yy_create_buffer</A> +<LI><A HREF="flex.html#IDX183">yy_delete_buffer</A> +<LI><A HREF="flex.html#IDX186">yy_flush_buffer</A> +<LI><A HREF="flex.html#IDX187">yy_new_buffer</A> +<LI><A HREF="flex.html#IDX198">YY_NEW_FILE (now obsolete)</A> +<LI><A HREF="flex.html#IDX174">yy_pop_state</A> +<LI><A HREF="flex.html#IDX173">yy_push_state</A> +<LI><A HREF="flex.html#IDX195">yy_scan_buffer</A> +<LI><A HREF="flex.html#IDX193">yy_scan_bytes</A> +<LI><A HREF="flex.html#IDX192">yy_scan_string</A> +<LI><A HREF="flex.html#IDX206">yy_set_bol</A> +<LI><A HREF="flex.html#IDX204">yy_set_interactive</A> +<LI><A HREF="flex.html#IDX181">yy_switch_to_buffer</A> +<LI><A HREF="flex.html#IDX175">yy_top_state</A> +<LI><A HREF="flex.html#IDX377">yyFlexLexer constructor (C++ only)</A> +<LI><A HREF="flex.html#IDX418">yyget_debug</A> +<LI><A HREF="flex.html#IDX406">yyget_extra</A>, <A HREF="flex.html#IDX420">yyget_extra</A> +<LI><A HREF="flex.html#IDX412">yyget_in</A> +<LI><A HREF="flex.html#IDX411">yyget_leng</A> +<LI><A HREF="flex.html#IDX414">yyget_lineno</A> +<LI><A HREF="flex.html#IDX472">yyget_lloc</A> +<LI><A HREF="flex.html#IDX471">yyget_lval</A> +<LI><A HREF="flex.html#IDX413">yyget_out</A> +<LI><A HREF="flex.html#IDX410">yyget_text</A> +<LI><A HREF="flex.html#IDX371">YYLeng (C++ only)</A> +<LI><A HREF="flex.html#IDX378">yylex (C++ version)</A> +<LI><A HREF="flex.html#IDX475">yylex (reentrant version)</A> +<LI><A HREF="flex.html#IDX400">yylex_destroy</A> +<LI><A HREF="flex.html#IDX399">yylex_init</A> +<LI><A HREF="flex.html#IDX218">yyrestart</A> +<LI><A HREF="flex.html#IDX419">yyset_debug</A> +<LI><A HREF="flex.html#IDX407">yyset_extra</A>, <A HREF="flex.html#IDX421">yyset_extra</A> +<LI><A HREF="flex.html#IDX415">yyset_in</A> +<LI><A HREF="flex.html#IDX417">yyset_lineno</A> +<LI><A HREF="flex.html#IDX474">yyset_lloc</A> +<LI><A HREF="flex.html#IDX473">yyset_lval</A> +<LI><A HREF="flex.html#IDX416">yyset_out</A> +<LI><A HREF="flex.html#IDX449">yytables_destroy</A> +<LI><A HREF="flex.html#IDX448">yytables_fload</A> +<LI><A HREF="flex.html#IDX137">yyterminate</A> +<LI><A HREF="flex.html#IDX370">YYText (C++ only)</A> </DIR> -<H2><A NAME="SEC84" HREF="flex_toc.html#TOC84">Index of Variables</A></H2> +<H2><A NAME="SEC160" HREF="flex_toc.html#TOC160">Index of Variables</A></H2> <P> This is an index of variables, constants, and preprocessor macros @@ -6563,30 +9496,30 @@ <P> <H2><A NAME="vindex_i">i</A></H2> <DIR> -<LI><A HREF="flex.html#IDX132">INITIAL</A> +<LI><A HREF="flex.html#IDX158">INITIAL</A> </DIR> <H2><A NAME="vindex_y">y</A></H2> <DIR> -<LI><A HREF="flex.html#IDX194">YY_CURRENT_BUFFER</A> -<LI><A HREF="flex.html#IDX168">YY_END_OF_BUFFER_CHAR</A> -<LI><A HREF="flex.html#IDX246">yy_globals (reentrant only)</A> -<LI><A HREF="flex.html#IDX176">YY_NUM_RULES</A> -<LI><A HREF="flex.html#IDX141">YY_START</A>, <A HREF="flex.html#IDX195">YY_START</A> -<LI><A HREF="flex.html#IDX255">yyextra</A> -<LI><A HREF="flex.html#IDX191">yyin</A> -<LI><A HREF="flex.html#IDX190">yyleng</A> -<LI><A HREF="flex.html#IDX263">yylloc</A> -<LI><A HREF="flex.html#IDX188">YYLMAX</A> -<LI><A HREF="flex.html#IDX262">yylval</A> -<LI><A HREF="flex.html#IDX197">yylval, with yacc</A> -<LI><A HREF="flex.html#IDX193">yyout</A> -<LI><A HREF="flex.html#IDX67">yytext</A>, <A HREF="flex.html#IDX185">yytext</A> +<LI><A HREF="flex.html#IDX220">YY_CURRENT_BUFFER</A> +<LI><A HREF="flex.html#IDX194">YY_END_OF_BUFFER_CHAR</A> +<LI><A HREF="flex.html#IDX202">YY_NUM_RULES</A> +<LI><A HREF="flex.html#IDX167">YY_START</A>, <A HREF="flex.html#IDX221">YY_START</A> +<LI><A HREF="flex.html#IDX404">yyextra</A> +<LI><A HREF="flex.html#IDX217">yyin</A> +<LI><A HREF="flex.html#IDX216">yyleng</A> +<LI><A HREF="flex.html#IDX468">yylloc</A> +<LI><A HREF="flex.html#IDX214">YYLMAX</A> +<LI><A HREF="flex.html#IDX467">yylval</A> +<LI><A HREF="flex.html#IDX223">yylval, with yacc</A> +<LI><A HREF="flex.html#IDX219">yyout</A> +<LI><A HREF="flex.html#IDX395">yyscanner (reentrant only)</A> +<LI><A HREF="flex.html#IDX92">yytext</A>, <A HREF="flex.html#IDX211">yytext</A> </DIR> -<H2><A NAME="SEC85" HREF="flex_toc.html#TOC85">Index of Data Types</A></H2> +<H2><A NAME="SEC161" HREF="flex_toc.html#TOC161">Index of Data Types</A></H2> <P> Jump to: <A HREF="#tindex_f">f</A> @@ -6595,23 +9528,23 @@ <P> <H2><A NAME="tindex_f">f</A></H2> <DIR> -<LI><A HREF="flex.html#IDX227">FlexLexer (C++ only)</A> +<LI><A HREF="flex.html#IDX376">FlexLexer (C++ only)</A> </DIR> <H2><A NAME="tindex_y">y</A></H2> <DIR> -<LI><A HREF="flex.html#IDX154">YY_BUFFER_STATE</A> -<LI><A HREF="flex.html#IDX256">YY_EXTRA_TYPE (reentrant only)</A> -<LI><A HREF="flex.html#IDX170">yy_size_t</A> -<LI><A HREF="flex.html#IDX226">yyFlexLexer (C++ only)</A> -<LI><A HREF="flex.html#IDX264">YYLTYPE</A> -<LI><A HREF="flex.html#IDX260">yyscan_t (reentrant only)</A> -<LI><A HREF="flex.html#IDX265">YYSTYPE</A> +<LI><A HREF="flex.html#IDX180">YY_BUFFER_STATE</A> +<LI><A HREF="flex.html#IDX405">YY_EXTRA_TYPE (reentrant only)</A> +<LI><A HREF="flex.html#IDX196">yy_size_t</A> +<LI><A HREF="flex.html#IDX375">yyFlexLexer (C++ only)</A> +<LI><A HREF="flex.html#IDX469">YYLTYPE</A> +<LI><A HREF="flex.html#IDX409">yyscan_t (reentrant only)</A> +<LI><A HREF="flex.html#IDX470">YYSTYPE</A> </DIR> -<H2><A NAME="SEC86" HREF="flex_toc.html#TOC86">Index of Hooks</A></H2> +<H2><A NAME="SEC162" HREF="flex_toc.html#TOC162">Index of Hooks</A></H2> <P> This is an index of "hooks" that the user may define. These hooks typically correspond @@ -6624,175 +9557,254 @@ <P> <H2><A NAME="hkindex_y">y</A></H2> <DIR> -<LI><A HREF="flex.html#IDX184">YY_BREAK</A> -<LI><A HREF="flex.html#IDX174">YY_USER_ACTION</A> -<LI><A HREF="flex.html#IDX177">YY_USER_INIT</A> +<LI><A HREF="flex.html#IDX210">YY_BREAK</A> +<LI><A HREF="flex.html#IDX200">YY_USER_ACTION</A> +<LI><A HREF="flex.html#IDX203">YY_USER_INIT</A> </DIR> -<H2><A NAME="SEC87" HREF="flex_toc.html#TOC87">Index of Examples</A></H2> +<H2><A NAME="SEC163" HREF="flex_toc.html#TOC163">Index of Scanner Options</A></H2> + <P> Jump to: -<A HREF="#exindex_<"><</A> +<A HREF="#opindex_-">-</A> +- +<A HREF="#opindex_7">7</A> - -<A HREF="#exindex_a">a</A> +<A HREF="#opindex_8">8</A> - -<A HREF="#exindex_b">b</A> +<A HREF="#opindex_a">a</A> - -<A HREF="#exindex_c">c</A> +<A HREF="#opindex_b">b</A> - -<A HREF="#exindex_d">d</A> +<A HREF="#opindex_c">c</A> - -<A HREF="#exindex_e">e</A> +<A HREF="#opindex_d">d</A> - -<A HREF="#exindex_f">f</A> +<A HREF="#opindex_e">e</A> - -<A HREF="#exindex_g">g</A> +<A HREF="#opindex_f">f</A> - -<A HREF="#exindex_h">h</A> +<A HREF="#opindex_h">h</A> - -<A HREF="#exindex_m">m</A> +<A HREF="#opindex_i">i</A> - -<A HREF="#exindex_n">n</A> +<A HREF="#opindex_l">l</A> - -<A HREF="#exindex_p">p</A> +<A HREF="#opindex_m">m</A> - -<A HREF="#exindex_r">r</A> +<A HREF="#opindex_n">n</A> - -<A HREF="#exindex_s">s</A> +<A HREF="#opindex_o">o</A> - -<A HREF="#exindex_t">t</A> +<A HREF="#opindex_p">p</A> - -<A HREF="#exindex_u">u</A> +<A HREF="#opindex_r">r</A> - -<A HREF="#exindex_w">w</A> +<A HREF="#opindex_s">s</A> - -<A HREF="#exindex_y">y</A> +<A HREF="#opindex_t">t</A> +- +<A HREF="#opindex_v">v</A> +- +<A HREF="#opindex_w">w</A> +- +<A HREF="#opindex_y">y</A> <P> -<H2><A NAME="exindex_<"><</A></H2> +<H2><A NAME="opindex_-">-</A></H2> +<DIR> +<LI><A HREF="flex.html#IDX283">-+</A> +<LI><A HREF="flex.html#IDX254">--7bit</A> +<LI><A HREF="flex.html#IDX257">--8bit</A> +<LI><A HREF="flex.html#IDX301">--align</A> +<LI><A HREF="flex.html#IDX261">--always-interactive</A> +<LI><A HREF="flex.html#IDX286">--array</A> +<LI><A HREF="flex.html#IDX321">--backup</A> +<LI><A HREF="flex.html#IDX248">--batch</A> +<LI><A HREF="flex.html#IDX275">--bison-bridge</A> +<LI><A HREF="flex.html#IDX284">--c++</A> +<LI><A HREF="flex.html#IDX242">--case-insensitive</A> +<LI><A HREF="flex.html#IDX324">--debug</A> +<LI><A HREF="flex.html#IDX259">--default</A> +<LI><A HREF="flex.html#IDX304">--ecs</A> +<LI><A HREF="flex.html#IDX318">--fast</A> +<LI><A HREF="flex.html#IDX315">--full</A> +<LI><A HREF="flex.html#IDX228">--header-file</A> +<LI><A HREF="flex.html#IDX345">--help</A> +<LI><A HREF="flex.html#IDX251">--interactive</A> +<LI><A HREF="flex.html#IDX245">--lex-compat</A> +<LI><A HREF="flex.html#IDX293">--main</A> +<LI><A HREF="flex.html#IDX309">--meta-ecs</A> +<LI><A HREF="flex.html#IDX263">--never-interactive</A> +<LI><A HREF="flex.html#IDX330">--nodefault</A> +<LI><A HREF="flex.html#IDX278">--noline</A> +<LI><A HREF="flex.html#IDX295">--nounistd</A> +<LI><A HREF="flex.html#IDX336">--nowarn</A> +<LI><A HREF="flex.html#IDX231">--outfile</A> +<LI><A HREF="flex.html#IDX327">--perf-report</A> +<LI><A HREF="flex.html#IDX288">--pointer</A> +<LI><A HREF="flex.html#IDX265">--posix</A> +<LI><A HREF="flex.html#IDX291">--prefix</A> +<LI><A HREF="flex.html#IDX312">--read</A> +<LI><A HREF="flex.html#IDX281">--reentrant</A> +<LI><A HREF="flex.html#IDX236">--skel</A> +<LI><A HREF="flex.html#IDX267">--stack</A> +<LI><A HREF="flex.html#IDX269">--stdinit</A> +<LI><A HREF="flex.html#IDX234">--stdout</A> +<LI><A HREF="flex.html#IDX237">--tables-file</A> +<LI><A HREF="flex.html#IDX239">--tables-verify</A> +<LI><A HREF="flex.html#IDX333">--trace</A> +<LI><A HREF="flex.html#IDX339">--verbose</A> +<LI><A HREF="flex.html#IDX348">--version</A> +<LI><A HREF="flex.html#IDX341">--warn</A> +<LI><A HREF="flex.html#IDX297">--yyclass</A> +<LI><A HREF="flex.html#IDX271">--yylineno</A> +<LI><A HREF="flex.html#IDX273">--yywrap</A> +<LI><A HREF="flex.html#IDX253">-7</A> +<LI><A HREF="flex.html#IDX256">-8</A> +<LI><A HREF="flex.html#IDX247">-B</A> +<LI><A HREF="flex.html#IDX320">-b</A> +<LI><A HREF="flex.html#IDX343">-c</A> +<LI><A HREF="flex.html#IDX299">-C</A> +<LI><A HREF="flex.html#IDX300">-Ca</A> +<LI><A HREF="flex.html#IDX303">-Ce</A> +<LI><A HREF="flex.html#IDX307">-CF</A> +<LI><A HREF="flex.html#IDX306">-Cf</A> +<LI><A HREF="flex.html#IDX308">-Cm</A> +<LI><A HREF="flex.html#IDX311">-Cr</A> +<LI><A HREF="flex.html#IDX323">-d</A> +<LI><A HREF="flex.html#IDX314">-f</A> +<LI><A HREF="flex.html#IDX317">-F</A> +<LI><A HREF="flex.html#IDX344">-h</A> +<LI><A HREF="flex.html#IDX250">-I</A> +<LI><A HREF="flex.html#IDX241">-i</A> +<LI><A HREF="flex.html#IDX277">-L</A> +<LI><A HREF="flex.html#IDX244">-l</A> +<LI><A HREF="flex.html#IDX346">-n</A> +<LI><A HREF="flex.html#IDX230">-o</A> +<LI><A HREF="flex.html#IDX326">-p</A> +<LI><A HREF="flex.html#IDX290">-P</A> +<LI><A HREF="flex.html#IDX280">-R</A> +<LI><A HREF="flex.html#IDX329">-s</A> +<LI><A HREF="flex.html#IDX233">-t</A> +<LI><A HREF="flex.html#IDX332">-T</A> +<LI><A HREF="flex.html#IDX347">-V</A> +<LI><A HREF="flex.html#IDX338">-v</A> +<LI><A HREF="flex.html#IDX335">-w</A> +<LI><A HREF="flex.html#IDX264">-X</A> +</DIR> +<H2><A NAME="opindex_7">7</A></H2> +<DIR> +<LI><A HREF="flex.html#IDX255">7bit</A> +</DIR> +<H2><A NAME="opindex_8">8</A></H2> +<DIR> +<LI><A HREF="flex.html#IDX258">8bit</A> +</DIR> +<H2><A NAME="opindex_a">a</A></H2> +<DIR> +<LI><A HREF="flex.html#IDX302">align</A> +<LI><A HREF="flex.html#IDX262">always-interactive</A> +<LI><A HREF="flex.html#IDX287">array</A> +</DIR> +<H2><A NAME="opindex_b">b</A></H2> <DIR> -<LI><A HREF="flex.html#IDX173"><<EOF>>, use of</A> +<LI><A HREF="flex.html#IDX322">backup</A> +<LI><A HREF="flex.html#IDX249">batch</A> +<LI><A HREF="flex.html#IDX276">bison-bridge</A> </DIR> -<H2><A NAME="exindex_a">a</A></H2> +<H2><A NAME="opindex_c">c</A></H2> <DIR> -<LI><A HREF="flex.html#IDX253">accessor functions, use of</A> +<LI><A HREF="flex.html#IDX285">c++</A> +<LI><A HREF="flex.html#IDX243">case-insensitive</A> </DIR> -<H2><A NAME="exindex_b">b</A></H2> +<H2><A NAME="opindex_d">d</A></H2> <DIR> -<LI><A HREF="flex.html#IDX209">backing up, eliminating</A> -<LI><A HREF="flex.html#IDX211">backing up, eliminating by adding error rules</A> -<LI><A HREF="flex.html#IDX212">backing up, eliminating with catch-all rule</A> -<LI><A HREF="flex.html#IDX272">bison, parser</A> -<LI><A HREF="flex.html#IDX271">bison, scanner to be called from bison</A> +<LI><A HREF="flex.html#IDX325">debug</A> +<LI><A HREF="flex.html#IDX260">default</A> </DIR> -<H2><A NAME="exindex_c">c</A></H2> +<H2><A NAME="opindex_e">e</A></H2> <DIR> -<LI><A HREF="flex.html#IDX239">C++ scanners, including multiple scanners</A> -<LI><A HREF="flex.html#IDX235">C++ scanners, use of</A> -<LI><A HREF="flex.html#IDX26">comments in the input</A> -<LI><A HREF="flex.html#IDX72">compressing whitespace</A> -<LI><A HREF="flex.html#IDX3">counting characters and lines</A> +<LI><A HREF="flex.html#IDX305">ecs</A> </DIR> -<H2><A NAME="exindex_d">d</A></H2> +<H2><A NAME="opindex_f">f</A></H2> <DIR> -<LI><A HREF="flex.html#IDX70">deleting lines from input</A> -<LI><A HREF="flex.html#IDX104">discarding C comments</A> +<LI><A HREF="flex.html#IDX319">fast</A> +<LI><A HREF="flex.html#IDX316">full</A> </DIR> -<H2><A NAME="exindex_e">e</A></H2> +<H2><A NAME="opindex_h">h</A></H2> <DIR> -<LI><A HREF="flex.html#IDX284">error messages, end of buffer missed</A> -<LI><A HREF="flex.html#IDX144">extended scope of start conditions</A> +<LI><A HREF="flex.html#IDX229">header-file</A> </DIR> -<H2><A NAME="exindex_f">f</A></H2> +<H2><A NAME="opindex_i">i</A></H2> <DIR> -<LI><A HREF="flex.html#IDX8">format of input file</A> +<LI><A HREF="flex.html#IDX252">interactive</A> </DIR> -<H2><A NAME="exindex_g">g</A></H2> +<H2><A NAME="opindex_l">l</A></H2> <DIR> -<LI><A HREF="flex.html#IDX140">getting current start state with YY_START</A> +<LI><A HREF="flex.html#IDX246">lex-compat</A> </DIR> -<H2><A NAME="exindex_h">h</A></H2> +<H2><A NAME="opindex_m">m</A></H2> <DIR> -<LI><A HREF="flex.html#IDX164">handling include files with multiple input buffers</A> +<LI><A HREF="flex.html#IDX294">main</A> +<LI><A HREF="flex.html#IDX310">meta-ecs</A> </DIR> -<H2><A NAME="exindex_m">m</A></H2> +<H2><A NAME="opindex_n">n</A></H2> <DIR> -<LI><A HREF="flex.html#IDX298">Makefile, example of implicit rules</A> -<LI><A HREF="flex.html#IDX299">Makefile, explicit example</A> -<LI><A HREF="flex.html#IDX142">matching C-style double-quoted strings</A> -<LI><A HREF="flex.html#IDX63">minimal scanner</A> +<LI><A HREF="flex.html#IDX331">nodefault</A> +<LI><A HREF="flex.html#IDX279">noline</A> +<LI><A HREF="flex.html#IDX296">nounistd</A> +<LI><A HREF="flex.html#IDX337">nowarn</A> +<LI><A HREF="flex.html#IDX435">noyyalloc</A> </DIR> -<H2><A NAME="exindex_n">n</A></H2> +<H2><A NAME="opindex_o">o</A></H2> <DIR> -<LI><A HREF="flex.html#IDX286">name definitions, not POSIX</A> +<LI><A HREF="flex.html#IDX232">outfile</A> </DIR> -<H2><A NAME="exindex_p">p</A></H2> +<H2><A NAME="opindex_p">p</A></H2> <DIR> -<LI><A HREF="flex.html#IDX4">Pascal-like language</A> -<LI><A HREF="flex.html#IDX13">pattern aliases, defining</A> -<LI><A HREF="flex.html#IDX14">pattern aliases, use of</A> -<LI><A HREF="flex.html#IDX287">patterns and actions on different lines</A> -<LI><A HREF="flex.html#IDX52">patterns, character class equivalence</A> -<LI><A HREF="flex.html#IDX60">patterns, end of line</A> -<LI><A HREF="flex.html#IDX47">patterns, grouping and precedence</A> -<LI><A HREF="flex.html#IDX58">patterns, invalid trailing context</A> -<LI><A HREF="flex.html#IDX48">patterns, repetitions with grouping</A> -<LI><A HREF="flex.html#IDX59">patterns, special characters treated as normal</A> -<LI><A HREF="flex.html#IDX29">patterns, syntax</A> -<LI><A HREF="flex.html#IDX50">patterns, valid character classes</A> -<LI><A HREF="flex.html#IDX214">performance optimization, matching longer tokens</A> -<LI><A HREF="flex.html#IDX217">performance optimization, recognizing keywords</A> +<LI><A HREF="flex.html#IDX328">perf-report</A> +<LI><A HREF="flex.html#IDX289">pointer</A> +<LI><A HREF="flex.html#IDX266">posix</A> +<LI><A HREF="flex.html#IDX292">prefix</A> </DIR> -<H2><A NAME="exindex_r">r</A></H2> +<H2><A NAME="opindex_r">r</A></H2> <DIR> -<LI><A HREF="flex.html#IDX136">recognizing C comments</A> -<LI><A HREF="flex.html#IDX241">reentrant scanners, multiple interleaved scanners</A> -<LI><A HREF="flex.html#IDX242">reentrant scanners, recursive invocation</A> -<LI><A HREF="flex.html#IDX86">REJECT</A> -<LI><A HREF="flex.html#IDX87">REJECT, calling multiple times</A> -<LI><A HREF="flex.html#IDX285">restarting the scanner</A> +<LI><A HREF="flex.html#IDX313">read</A> +<LI><A HREF="flex.html#IDX282">reentrant</A> </DIR> -<H2><A NAME="exindex_s">s</A></H2> +<H2><A NAME="opindex_s">s</A></H2> <DIR> -<LI><A HREF="flex.html#IDX122">start conditions, basic</A> -<LI><A HREF="flex.html#IDX129">start conditions, behavior of default rule</A> -<LI><A HREF="flex.html#IDX126">start conditions, exclusive</A> -<LI><A HREF="flex.html#IDX134">start conditions, for different interpretations of same input</A> -<LI><A HREF="flex.html#IDX125">start conditions, inclusive</A> -<LI><A HREF="flex.html#IDX123">start conditions, multiple</A> -<LI><A HREF="flex.html#IDX128">start conditions, use of wildcard condition (<*>)</A> -<LI><A HREF="flex.html#IDX133">start conditions, using BEGIN</A> +<LI><A HREF="flex.html#IDX268">stack</A> +<LI><A HREF="flex.html#IDX270">stdinit</A> +<LI><A HREF="flex.html#IDX235">stdout</A> </DIR> -<H2><A NAME="exindex_t">t</A></H2> +<H2><A NAME="opindex_t">t</A></H2> <DIR> -<LI><A HREF="flex.html#IDX213">trailing context, variable length</A> +<LI><A HREF="flex.html#IDX238">tables-file</A> +<LI><A HREF="flex.html#IDX240">tables-verify</A> +<LI><A HREF="flex.html#IDX334">trace</A> </DIR> -<H2><A NAME="exindex_u">u</A></H2> +<H2><A NAME="opindex_v">v</A></H2> <DIR> -<LI><A HREF="flex.html#IDX97">unput() to push back characters</A> -<LI><A HREF="flex.html#IDX138">using integer values of start condition names</A> +<LI><A HREF="flex.html#IDX340">verbose</A> </DIR> -<H2><A NAME="exindex_w">w</A></H2> +<H2><A NAME="opindex_w">w</A></H2> <DIR> -<LI><A HREF="flex.html#IDX293">warning, dangerous trailing context</A> -<LI><A HREF="flex.html#IDX291">warning, rule cannot be matched</A> +<LI><A HREF="flex.html#IDX342">warn</A> </DIR> -<H2><A NAME="exindex_y">y</A></H2> +<H2><A NAME="opindex_y">y</A></H2> <DIR> -<LI><A HREF="flex.html#IDX198">yacc interface</A> -<LI><A HREF="flex.html#IDX259">YY_EXTRA_TYPE, defining your own type</A> -<LI><A HREF="flex.html#IDX119">YY_INPUT, overriding the input mechanism</A> -<LI><A HREF="flex.html#IDX175">YY_USER_ACTION to track each time a rule is matched</A> -<LI><A HREF="flex.html#IDX94">yyless() to push back characters</A> -<LI><A HREF="flex.html#IDX114">yylex, overriding the prototype</A> -<LI><A HREF="flex.html#IDX90">yymore() to append token to previous token</A> +<LI><A HREF="flex.html#IDX298">yyclass</A> +<LI><A HREF="flex.html#IDX272">yylineno</A> +<LI><A HREF="flex.html#IDX274">yywrap</A> </DIR> <P><HR><P> -This document was generated on 2 July 2002 using +This document was generated on 9 November 2002 using <A HREF="http://wwwinfo.cern.ch/dis/texi2html/">texi2html</A> 1.56k. </BODY> </HTML>

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