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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>1 Lexers</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="file:///Users/mb/git/racket/racket/doc/local-redirect/local-redirect.js"></script><script type="text/javascript" src="file:///Users/MB/Library/Racket/6.8.0.1/doc/local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">▼</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x">Parser Tools:<span class="mywbr"> </span> <span class="stt">lex</span> and <span class="stt">yacc</span>-<wbr></wbr>style Parsing</a></td></tr></table></div><div class="tocviewsublisttop" style="display: block;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Lexers</a></td></tr><tr><td align="right">2 </td><td><a href="LALR_1__Parsers.html" class="tocviewlink" data-pltdoc="x">LALR(1) Parsers</a></td></tr><tr><td align="right">3 </td><td><a href="Context-Free_Parsers.html" class="tocviewlink" data-pltdoc="x">Context-<wbr></wbr>Free Parsers</a></td></tr><tr><td align="right">4 </td><td><a href="Converting_yacc_or_bison_Grammars.html" class="tocviewlink" data-pltdoc="x">Converting <span class="stt">yacc</span> or <span class="stt">bison</span> Grammars</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">►</a></td><td>1 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Lexers</a></td></tr></table><div class="tocviewsublistbottom" style="display: none;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">1.1 </td><td><a href="#%28part._.Creating_a_.Lexer%29" class="tocviewlink" data-pltdoc="x">Creating a Lexer</a></td></tr><tr><td align="right">1.2 </td><td><a href="#%28part._.Lexer_.Abbreviations_and_.Macros%29" class="tocviewlink" data-pltdoc="x">Lexer Abbreviations and Macros</a></td></tr><tr><td align="right">1.3 </td><td><a href="#%28part._.Lexer_.S.R.E_.Operators%29" class="tocviewlink" data-pltdoc="x">Lexer SRE Operators</a></td></tr><tr><td align="right">1.4 </td><td><a href="#%28part._.Lexer_.Legacy_.Operators%29" class="tocviewlink" data-pltdoc="x">Lexer Legacy Operators</a></td></tr><tr><td align="right">1.5 </td><td><a href="#%28part._.Tokens%29" class="tocviewlink" data-pltdoc="x">Tokens</a></td></tr></table></div></div></div><div class="tocsub"><div class="tocsubtitle">On this page:</div><table class="tocsublist" cellspacing="0"><tr><td><span class="tocsublinknumber">1.1<tt> </tt></span><a href="#%28part._.Creating_a_.Lexer%29" class="tocsubseclink" data-pltdoc="x">Creating a Lexer</a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">lexer</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer-src-pos%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">lexer-<wbr></wbr>src-<wbr></wbr>pos</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._start-pos%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">start-<wbr></wbr>pos</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._end-pos%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">end-<wbr></wbr>pos</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexeme%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">lexeme</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._input-port%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">input-<wbr></wbr>port</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._return-without-pos%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">return-<wbr></wbr>without-<wbr></wbr>pos</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">position</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position-token%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">position-<wbr></wbr>token</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._file-path%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">file-<wbr></wbr>path</span></span></a></td></tr><tr><td><span class="tocsublinknumber">1.2<tt> </tt></span><a href="#%28part._.Lexer_.Abbreviations_and_.Macros%29" class="tocsubseclink" data-pltdoc="x">Lexer Abbreviations and Macros</a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._char-set%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">char-<wbr></wbr>set</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-char%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">any-<wbr></wbr>char</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">any-<wbr></wbr>string</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._nothing%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">nothing</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._alphabetic%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">alphabetic</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lower-case%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">lower-<wbr></wbr>case</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._upper-case%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">upper-<wbr></wbr>case</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._title-case%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">title-<wbr></wbr>case</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._numeric%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">numeric</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._symbolic%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">symbolic</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._punctuation%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">punctuation</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._graphic%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">graphic</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._whitespace%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">whitespace</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._blank%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">blank</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._iso-control%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">iso-<wbr></wbr>control</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-lex-abbrev%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">define-<wbr></wbr>lex-<wbr></wbr>abbrev</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-lex-abbrevs%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">define-<wbr></wbr>lex-<wbr></wbr>abbrevs</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-lex-trans%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">define-<wbr></wbr>lex-<wbr></wbr>trans</span></span></a></td></tr><tr><td><span class="tocsublinknumber">1.3<tt> </tt></span><a href="#%28part._.Lexer_.S.R.E_.Operators%29" class="tocsubseclink" data-pltdoc="x">Lexer SRE Operators</a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">*</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2B%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">+</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">?</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3d%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">=</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3e~3d%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">>=</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%2A%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">**</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._or%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">or</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">:</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._seq%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">seq</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~26%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">&</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._-%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink"><span class="nobreak">-</span></span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~7e%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">~</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2F%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">/</span></span></a></td></tr><tr><td><span class="tocsublinknumber">1.4<tt> </tt></span><a href="#%28part._.Lexer_.Legacy_.Operators%29" class="tocsubseclink" data-pltdoc="x">Lexer Legacy Operators</a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-plt-v200..rkt%29._epsilon%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">epsilon</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex-plt-v200..rkt%29._~7e%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">~</span></span></a></td></tr><tr><td><span class="tocsublinknumber">1.5<tt> </tt></span><a href="#%28part._.Tokens%29" class="tocsubseclink" data-pltdoc="x">Tokens</a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-tokens%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">define-<wbr></wbr>tokens</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-empty-tokens%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">define-<wbr></wbr>empty-<wbr></wbr>tokens</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._token-name%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">token-<wbr></wbr>name</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._token-value%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">token-<wbr></wbr>value</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._token~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">token?</span></span></a></td></tr></table></div></div><div class="maincolumn"><div class="main"><div class="navsettop"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.8.0.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.8.0.1");">top</a></span><span class="navright"> <a href="index.html" title="backward to "Parser Tools: lex and yacc-style Parsing"" data-pltdoc="x">← prev</a> <a href="index.html" title="up to "Parser Tools: lex and yacc-style Parsing"" data-pltdoc="x">up</a> <a href="LALR_1__Parsers.html" title="forward to "2 LALR(1) Parsers"" data-pltdoc="x">next →</a></span> </div><h3 x-source-module="(lib "parser-tools/br-parser-tools.scrbl")" x-source-pkg="br-parser-tools-doc" x-part-tag=""Lexers"">1<tt> </tt><a name="(part._.Lexers)"></a><a name="(mod-path._br-parser-tools/lex)"></a><a name="(idx._(gentag._0._(lib._parser-tools/br-parser-tools..scrbl)))"></a><a name="(idx._(gentag._1._(lib._parser-tools/br-parser-tools..scrbl)))"></a><a name="(idx._(gentag._2._(lib._parser-tools/br-parser-tools..scrbl)))"></a>Lexers</h3><p><table cellspacing="0" cellpadding="0" class="defmodule"><tr><td align="left" colspan="2"><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="stt"> </span><a href="" class="RktModLink" data-pltdoc="x"><span class="RktSym">br-parser-tools/lex</span></a><span class="RktPn">)</span></td></tr><tr><td align="left"> </td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <span class="stt">br-parser-tools-lib</span></span></td></tr></table></p><h4 x-source-module="(lib "parser-tools/br-parser-tools.scrbl")" x-source-pkg="br-parser-tools-doc" x-part-tag=""Creating_a_Lexer"">1.1<tt> </tt><a name="(part._.Creating_a_.Lexer)"></a>Creating a Lexer</h4><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex..rkt)._lexer))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">lexer</a></span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktVar">trigger</span><span class="hspace"> </span><span class="RktVar">action-expr</span><span class="RktPn">]</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="stt"> </span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="specgrammar"><tr><td align="right" valign="baseline"><span class="RktVar">trigger</span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">=</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktVar">re</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=port-ops.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._eof%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">eof</a></span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym">special</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym">special-comment</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td></tr><tr><td align="right" valign="baseline"><span class="RktVar">re</span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">=</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktVar">id</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktVar">string</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktVar">character</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym">repetition</span><span class="hspace"> </span><span class="RktVar">lo</span><span class="hspace"> </span><span class="RktVar">hi</span><span class="hspace"> </span><span class="RktVar">re</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym">union</span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym">intersection</span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym">complement</span><span class="hspace"> </span><span class="RktVar">re</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym">concatenation</span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym">char-range</span><span class="hspace"> </span><span class="RktVar">char</span><span class="hspace"> </span><span class="RktVar">char</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym">char-complement</span><span class="hspace"> </span><span class="RktVar">re</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktVar">id</span><span class="hspace"> </span><span class="RktVar">datum</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Produces a function that takes an input-port, matches the
|
|
<span class="RktVar">re</span> patterns against the buffer, and returns the result of
|
|
executing the corresponding <span class="RktVar">action-expr</span>. When multiple
|
|
patterns match, a lexer will choose the longest match, breaking
|
|
ties in favor of the rule appearing first.</div></p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>The implementation of <a href="http://docs.racket-lang.org/local-redirect/index.html?doc=syntax-color&rel=index.html%23%2528mod-path._syntax-color%252Fracket-lexer%2529&version=6.8.0.1" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">syntax-color/racket-lexer</span></a>
|
|
contains a lexer for the <a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=index.html&version=6.8.0.1" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">racket</span></a> language.
|
|
In addition, files in the <span class="stt">"examples"</span> sub-directory
|
|
of the <span class="stt">"br-parser-tools"</span> collection contain
|
|
simpler example lexers.</p></blockquote></blockquote></blockquote><p>An <span class="RktVar">re</span> is matched as follows:</p><ul><li><p><span class="RktVar">id</span> —<wbr></wbr> expands to the named <a name="(tech._lexer._abbreviation)"></a><span style="font-style: italic">lexer abbreviation</span>;
|
|
abbreviations are defined via <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-lex-abbrev%29%29" class="RktStxLink" data-pltdoc="x">define-lex-abbrev</a></span> or supplied by modules
|
|
like <a href="#%28mod-path._br-parser-tools%2Flex-sre%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">br-parser-tools/lex-sre</span></a>.</p></li><li><p><span class="RktVar">string</span> —<wbr></wbr> matches the sequence of characters in <span class="RktVar">string</span>.</p></li><li><p><span class="RktVar">character</span> —<wbr></wbr> matches a literal <span class="RktVar">character</span>.</p></li><li><p><span class="RktPn">(</span><span class="RktSym">repetition</span><span class="stt"> </span><span class="RktVar">lo</span><span class="stt"> </span><span class="RktVar">hi</span><span class="stt"> </span><span class="RktVar">re</span><span class="RktPn">)</span> —<wbr></wbr> matches <span class="RktVar">re</span> repeated between <span class="RktVar">lo</span>
|
|
and <span class="RktVar">hi</span> times, inclusive; <span class="RktVar">hi</span> can be <span class="RktVal">+inf.0</span> for unbounded repetitions.</p></li><li><p><span class="RktPn">(</span><span class="RktSym">union</span><span class="stt"> </span><span class="RktVar">re</span><span class="stt"> </span><span class="RktMeta"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._......%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">...</a></span><span class="RktPn">)</span> —<wbr></wbr> matches if any of the sub-expressions match</p></li><li><p><span class="RktPn">(</span><span class="RktSym">intersection</span><span class="stt"> </span><span class="RktVar">re</span><span class="stt"> </span><span class="RktMeta"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._......%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">...</a></span><span class="RktPn">)</span> —<wbr></wbr> matches if all of the <span class="RktVar">re</span>s match.</p></li><li><p><span class="RktPn">(</span><span class="RktSym">complement</span><span class="stt"> </span><span class="RktVar">re</span><span class="RktPn">)</span> —<wbr></wbr> matches anything that <span class="RktVar">re</span> does not.</p></li><li><p><span class="RktPn">(</span><span class="RktSym">concatenation</span><span class="stt"> </span><span class="RktVar">re</span><span class="stt"> </span><span class="RktMeta"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._......%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">...</a></span><span class="RktPn">)</span> —<wbr></wbr> matches each <span class="RktVar">re</span> in succession.</p></li><li><p><span class="RktPn">(</span><span class="RktSym">char-range</span><span class="stt"> </span><span class="RktVar">char</span><span class="stt"> </span><span class="RktVar">char</span><span class="RktPn">)</span> —<wbr></wbr> matches any character between the two (inclusive);
|
|
a single character string can be used as a <span class="RktVar">char</span>.</p></li><li><p><span class="RktPn">(</span><span class="RktSym">char-complement</span><span class="stt"> </span><span class="RktVar">re</span><span class="RktPn">)</span> —<wbr></wbr> matches any character not matched by <span class="RktVar">re</span>.
|
|
The sub-expression must be a set of characters <span class="RktVar">re</span>.</p></li><li><p><span class="RktPn">(</span><span class="RktVar">id</span><span class="stt"> </span><span class="RktVar">datum</span><span class="stt"> </span><span class="RktMeta"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._......%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">...</a></span><span class="RktPn">)</span> —<wbr></wbr> expands the <a name="(tech._lexer._macro)"></a><span style="font-style: italic">lexer macro</span> named <span class="RktVar">id</span>; macros
|
|
are defined via <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-lex-trans%29%29" class="RktStxLink" data-pltdoc="x">define-lex-trans</a></span>.</p></li></ul><p>Note that both <span class="RktPn">(</span><span class="RktSym">concatenation</span><span class="RktPn">)</span> and <span class="RktVal">""</span> match the
|
|
empty string, <span class="RktPn">(</span><span class="RktSym">union</span><span class="RktPn">)</span> matches nothing,
|
|
<span class="RktPn">(</span><span class="RktSym">intersection</span><span class="RktPn">)</span> matches any string, and
|
|
<span class="RktPn">(</span><span class="RktSym">char-complement</span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym">union</span><span class="RktPn">)</span><span class="RktPn">)</span> matches any single character.</p><p>The regular expression language is not designed to be used directly,
|
|
but rather as a basis for a user-friendly notation written with
|
|
regular expression macros. For example,
|
|
<a href="#%28mod-path._br-parser-tools%2Flex-sre%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">br-parser-tools/lex-sre</span></a> supplies operators from Olin
|
|
Shivers’s SREs, and <a href="#%28mod-path._br-parser-tools%2Flex-plt-v200%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">br-parser-tools/lex-plt-v200</span></a> supplies
|
|
(deprecated) operators from the previous version of this library.
|
|
Since those libraries provide operators whose names match other Racket
|
|
bindings, such as <span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=generic-numbers.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._%252A%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">*</a></span> and <span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=generic-numbers.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._%252B%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">+</a></span>, they normally must be
|
|
imported using a prefix:</p><blockquote class="SCodeFlow"><p><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._prefix-in%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">prefix-in</a></span><span class="hspace"> </span><span class="RktSym">:</span><span class="hspace"> </span><span class="RktSym">br-parser-tools/lex-sre</span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote><p>The suggested prefix is <span class="RktSym">:</span>, so that <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%29%29" class="RktStxLink" data-pltdoc="x">:*</a></span> and
|
|
<span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2B%29%29" class="RktStxLink" data-pltdoc="x">:+</a></span> are imported. Of course, a prefix other than <span class="RktSym">:</span>
|
|
(such as <span class="RktSym">re-</span>) will work too.</p><p>Since negation is not a common operator on regular expressions, here
|
|
are a few examples, using <span class="RktSym">:</span> prefixed SRE syntax:</p><ul><li><p><span class="RktPn">(</span><span class="RktSym">complement</span><span class="hspace"> </span><span class="RktVal">"1"</span><span class="RktPn">)</span></p><p>Matches all strings except the string <span class="RktVal">"1"</span>, including
|
|
<span class="RktVal">"11"</span>, <span class="RktVal">"111"</span>, <span class="RktVal">"0"</span>, <span class="RktVal">"01"</span>,
|
|
<span class="RktVal">""</span>, and so on.</p></li><li><p><span class="RktPn">(</span><span class="RktSym">complement</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%29%29" class="RktStxLink" data-pltdoc="x">:*</a></span><span class="hspace"> </span><span class="RktVal">"1"</span><span class="RktPn">)</span><span class="RktPn">)</span></p><p>Matches all strings that are not sequences of <span class="RktVal">"1"</span>,
|
|
including <span class="RktVal">"0"</span>, <span class="RktVal">"00"</span>, <span class="RktVal">"11110"</span>,
|
|
<span class="RktVal">"0111"</span>, <span class="RktVal">"11001010"</span> and so on.</p></li><li><p><table cellspacing="0" cellpadding="0" class="RktBlk" style="display: inline-table; vertical-align: text-top; margin-top: 0;"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~26%29%29" class="RktStxLink" data-pltdoc="x">:&</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxLink" data-pltdoc="x">::</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span><span class="hspace"> </span><span class="RktVal">"111"</span><span class="hspace"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">complement</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._or%29%29" class="RktStxLink" data-pltdoc="x">:or</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxLink" data-pltdoc="x">::</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span><span class="hspace"> </span><span class="RktVal">"01"</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2B%29%29" class="RktStxLink" data-pltdoc="x">:+</a></span><span class="hspace"> </span><span class="RktVal">"1"</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></p><p>Matches all strings that have 3 consecutive ones, but not those that
|
|
end in <span class="RktVal">"01"</span> and not those that are ones only. These
|
|
include <span class="RktVal">"1110"</span>, <span class="RktVal">"0001000111"</span> and <span class="RktVal">"0111"</span>
|
|
but not <span class="RktVal">""</span>, <span class="RktVal">"11"</span>, <span class="RktVal">"11101"</span>, <span class="RktVal">"111"</span>
|
|
and <span class="RktVal">"11111"</span>.</p></li><li><p><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxLink" data-pltdoc="x">::</a></span><span class="hspace"> </span><span class="RktVal">"/*"</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">complement</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxLink" data-pltdoc="x">::</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span><span class="hspace"> </span><span class="RktVal">"*/"</span><span class="hspace"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span><span class="RktPn">)</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">"*/"</span><span class="RktPn">)</span></p><p>Matches Java/C block comments. <span class="RktVal">"/**/"</span>,
|
|
<span class="RktVal">"/******/"</span>, <span class="RktVal">"/*////*/"</span>, <span class="RktVal">"/*asg4*/"</span> and so
|
|
on. It does not match <span class="RktVal">"/**/*/"</span>, <span class="RktVal">"/* */ */"</span> and so
|
|
on. <span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxLink" data-pltdoc="x">::</a></span><span class="stt"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span><span class="stt"> </span><span class="RktVal">"*/"</span><span class="stt"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span><span class="RktPn">)</span> matches any string
|
|
that has a <span class="RktVal">"*/"</span> in is, so <span class="RktPn">(</span><span class="RktSym">complement</span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxLink" data-pltdoc="x">::</a></span><span class="stt"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span><span class="stt"> </span><span class="RktVal">"*/"</span><span class="stt"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span><span class="RktPn">)</span><span class="RktPn">)</span> matches any string without a <span class="RktVal">"*/"</span> in it.</p></li><li><p><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxLink" data-pltdoc="x">::</a></span><span class="hspace"> </span><span class="RktVal">"/*"</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%29%29" class="RktStxLink" data-pltdoc="x">:*</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">complement</span><span class="hspace"> </span><span class="RktVal">"*/"</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">"*/"</span><span class="RktPn">)</span></p><p>Matches any string that starts with <span class="RktVal">"/*"</span> and ends with
|
|
<span class="RktVal">"*/"</span>, including <span class="RktVal">"/* */ */ */"</span>.
|
|
<span class="RktPn">(</span><span class="RktSym">complement</span><span class="stt"> </span><span class="RktVal">"*/"</span><span class="RktPn">)</span> matches any string except <span class="RktVal">"*/"</span>.
|
|
This includes <span class="RktVal">"*"</span> and <span class="RktVal">"/"</span> separately. Thus
|
|
<span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%29%29" class="RktStxLink" data-pltdoc="x">:*</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym">complement</span><span class="stt"> </span><span class="RktVal">"*/"</span><span class="RktPn">)</span><span class="RktPn">)</span> matches <span class="RktVal">"*/"</span> by first
|
|
matching <span class="RktVal">"*"</span> and then matching <span class="RktVal">"/"</span>. Any other
|
|
string is matched directly by <span class="RktPn">(</span><span class="RktSym">complement</span><span class="stt"> </span><span class="RktVal">"*/"</span><span class="RktPn">)</span>. In other
|
|
words, <span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%29%29" class="RktStxLink" data-pltdoc="x">:*</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym">complement</span><span class="stt"> </span><span class="RktVal">"xx"</span><span class="RktPn">)</span><span class="RktPn">)</span> = <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxLink" data-pltdoc="x">any-string</a></span>. It is
|
|
usually not correct to place a <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%29%29" class="RktStxLink" data-pltdoc="x">:*</a></span> around a
|
|
<span class="RktSym">complement</span>.</p></li></ul><p>The following binding have special meaning inside of a lexer
|
|
action:</p><ul><li><p><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._start-pos%29%29" class="RktStxLink" data-pltdoc="x">start-pos</a></span> —<wbr></wbr> a <span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position%29%29" class="RktValLink" data-pltdoc="x">position</a></span> struct for the first character matched.</p></li><li><p><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._end-pos%29%29" class="RktStxLink" data-pltdoc="x">end-pos</a></span> —<wbr></wbr> a <span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position%29%29" class="RktValLink" data-pltdoc="x">position</a></span> struct for the character after the last character in the match.</p></li><li><p><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexeme%29%29" class="RktStxLink" data-pltdoc="x">lexeme</a></span> —<wbr></wbr> the matched string.</p></li><li><p><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._input-port%29%29" class="RktStxLink" data-pltdoc="x">input-port</a></span> —<wbr></wbr> the input-port being
|
|
processed (this is useful for matching input with multiple
|
|
lexers).</p></li><li><p><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._return-without-pos%29%29" class="RktStxLink" data-pltdoc="x">return-without-pos</a></span><span class="stt"> </span><span class="RktSym">x</span><span class="RktPn">)</span> is a function (continuation) that
|
|
immediately returns the value of <span class="RktSym">x</span> from the lexer. This useful
|
|
in a src-pos lexer to prevent the lexer from adding source
|
|
information. For example:</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">get-token</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer-src-pos%29%29" class="RktStxLink" data-pltdoc="x">lexer-src-pos</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktMeta"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._......%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">...</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">(</span><span class="RktSym">comment</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">get-token</span><span class="hspace"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._input-port%29%29" class="RktStxLink" data-pltdoc="x">input-port</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktMeta"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._......%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">...</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote><p>would wrap the source location information for the comment around
|
|
the value of the recursive call. Using
|
|
<span class="RktPn">(</span><span class="RktPn">(</span><span class="RktSym">comment</span><span class="RktPn">)</span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._return-without-pos%29%29" class="RktStxLink" data-pltdoc="x">return-without-pos</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym">get-token</span><span class="stt"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._input-port%29%29" class="RktStxLink" data-pltdoc="x">input-port</a></span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span>
|
|
will cause the value of the recursive call to be returned without
|
|
wrapping position around it.</p></li></ul><p>The lexer raises an exception <span class="RktPn">(</span><span class="RktSym">exn:read</span><span class="RktPn">)</span> if none of the
|
|
regular expressions match the input. Hint: If <span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-char%29%29" class="RktStxLink" data-pltdoc="x">any-char</a></span><span class="stt"> </span><span class="RktVar">custom-error-behavior</span><span class="RktPn">)</span> is the last rule, then there will always
|
|
be a match, and <span class="RktVar">custom-error-behavior</span> is executed to
|
|
handle the error situation as desired, only consuming the first
|
|
character from the input buffer.</p><p>In addition to returning characters, input
|
|
ports can return <span class="RktSym">eof-object</span>s. Custom input ports can
|
|
also return a <span class="RktSym">special-comment</span> value to indicate a
|
|
non-textual comment, or return another arbitrary value (a
|
|
special). The non-<span class="RktVar">re</span> <span class="RktVar">trigger</span> forms handle these
|
|
cases:</p><ul><li><p>The <span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=port-ops.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._eof%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">eof</a></span><span class="RktPn">)</span> rule is matched when the input port
|
|
returns an <span class="RktSym">eof-object</span> value. If no <span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=port-ops.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._eof%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">eof</a></span><span class="RktPn">)</span>
|
|
rule is present, the lexer returns the symbol <span class="RktVal">'</span><span class="RktVal">eof</span>
|
|
when the port returns an <span class="RktSym">eof-object</span> value.</p></li><li><p>The <span class="RktPn">(</span><span class="RktSym">special-comment</span><span class="RktPn">)</span> rule is matched when the
|
|
input port returns a <span class="RktSym">special-comment</span> structure. If no
|
|
<span class="RktSym">special-comment</span> rule is present, the lexer
|
|
automatically tries to return the next token from the input
|
|
port.</p></li><li><p>The <span class="RktPn">(</span><span class="RktSym">special</span><span class="RktPn">)</span> rule is matched when the input
|
|
port returns a value other than a character,
|
|
<span class="RktSym">eof-object</span>, or <span class="RktSym">special-comment</span> structure. If
|
|
no <span class="RktPn">(</span><span class="RktSym">special</span><span class="RktPn">)</span> rule is present, the lexer returns
|
|
<span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=void.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._void%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">void</a></span><span class="RktPn">)</span>.</p></li></ul><p>End-of-files, specials, special-comments and special-errors cannot
|
|
be parsed via a rule using an ordinary regular expression
|
|
(but dropping down and manipulating the port to handle them
|
|
is possible in some situations).</p><p>Since the lexer gets its source information from the port, use
|
|
<span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=linecol.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._port-count-lines%2521%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">port-count-lines!</a></span> to enable the tracking of line and
|
|
column information. Otherwise, the line and column information
|
|
will return <span class="RktVal">#f</span>.</p><p>When peeking from the input port raises an exception (such as by
|
|
an embedded XML editor with malformed syntax), the exception can
|
|
be raised before all tokens preceding the exception have been
|
|
returned.</p><p>Each time the racket code for a lexer is compiled (e.g. when a
|
|
<span class="stt">".rkt"</span> file containing a <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer%29%29" class="RktStxLink" data-pltdoc="x">lexer</a></span> form is loaded),
|
|
the lexer generator is run. To avoid this overhead place the
|
|
lexer into a module and compile the module to a <span class="stt">".zo"</span>
|
|
bytecode file.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex..rkt)._lexer-src-pos))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer-src-pos%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">lexer-src-pos</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktVar">trigger</span><span class="hspace"> </span><span class="RktVar">action-expr</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer%29%29" class="RktStxLink" data-pltdoc="x">lexer</a></span>, but for each <span class="RktVar">action-result</span> produced by
|
|
an <span class="RktVar">action-expr</span>, returns <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._make-position-token%29%29" class="RktValLink" data-pltdoc="x">make-position-token</a></span><span class="stt"> </span><span class="RktVar">action-result</span><span class="stt"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._start-pos%29%29" class="RktStxLink" data-pltdoc="x">start-pos</a></span><span class="stt"> </span><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._end-pos%29%29" class="RktStxLink" data-pltdoc="x">end-pos</a></span><span class="RktPn">)</span> instead of simply
|
|
<span class="RktVar">action-result</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._start-pos))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._start-pos%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">start-pos</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._end-pos))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._end-pos%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">end-pos</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._lexeme))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexeme%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">lexeme</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._input-port))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._input-port%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">input-port</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._return-without-pos))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._return-without-pos%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">return-without-pos</a></span></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Use of these names outside of a <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer%29%29" class="RktStxLink" data-pltdoc="x">lexer</a></span> action is a syntax
|
|
error.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=define-struct.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._struct%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._br-parser-tools/lex..rkt)._position-col))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._position-line))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._position-offset))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._make-position))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._position~3f))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._struct~3aposition))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._position))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position%29%29" class="RktValDef RktValLink" data-pltdoc="x">position</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">offset</span><span class="stt"> </span><span class="RktSym">line</span><span class="stt"> </span><span class="RktSym">col</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._make-position%29%29" class="RktValLink" data-pltdoc="x">make-position</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">offset</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=number-types.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._exact-positive-integer%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">exact-positive-integer?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">line</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=number-types.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._exact-positive-integer%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">exact-positive-integer?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">col</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=number-types.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._exact-nonnegative-integer%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">exact-nonnegative-integer?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Instances of <span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position%29%29" class="RktValLink" data-pltdoc="x">position</a></span> are bound to <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._start-pos%29%29" class="RktStxLink" data-pltdoc="x">start-pos</a></span> and
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<span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._end-pos%29%29" class="RktStxLink" data-pltdoc="x">end-pos</a></span>. The <span class="RktSym">offset</span> field contains the offset of
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the character in the input. The <span class="RktSym">line</span> field contains the
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|
line number of the character. The <span class="RktSym">col</span> field contains the
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offset in the current line.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=define-struct.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._struct%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._br-parser-tools/lex..rkt)._position-token-end-pos))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._position-token-start-pos))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._position-token-token))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._make-position-token))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._position-token~3f))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._struct~3aposition-token))"></a><a name="(def._((lib._br-parser-tools/lex..rkt)._position-token))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position-token%29%29" class="RktValDef RktValLink" data-pltdoc="x">position-token</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">token</span><span class="stt"> </span><span class="RktSym">start-pos</span><span class="stt"> </span><span class="RktSym">end-pos</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._make-position-token%29%29" class="RktValLink" data-pltdoc="x">make-position-token</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">token</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=data-structure-contracts.html%23%2528def._%2528%2528lib._racket%252Fcontract%252Fprivate%252Fmisc..rkt%2529._any%252Fc%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">any/c</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">start-pos</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position~3f%29%29" class="RktValLink" data-pltdoc="x">position?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">end-pos</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position~3f%29%29" class="RktValLink" data-pltdoc="x">position?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Lexers created with <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer-src-pos%29%29" class="RktStxLink" data-pltdoc="x">lexer-src-pos</a></span> return instances of <span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._position-token%29%29" class="RktValLink" data-pltdoc="x">position-token</a></span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._br-parser-tools/lex..rkt)._file-path))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._file-path%29%29" class="RktValDef RktValLink" data-pltdoc="x">file-path</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=data-structure-contracts.html%23%2528def._%2528%2528lib._racket%252Fcontract%252Fprivate%252Fmisc..rkt%2529._any%252Fc%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">any/c</a></span></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._file-path%29%29" class="RktValDef RktValLink" data-pltdoc="x">file-path</a></span></span><span class="hspace"> </span><span class="RktVar">source</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=void.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._void%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">source</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=data-structure-contracts.html%23%2528def._%2528%2528lib._racket%252Fcontract%252Fprivate%252Fmisc..rkt%2529._any%252Fc%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">A parameter that the lexer uses as the source location if it
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raises a <span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=exns.html%23%2528def._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._exn%7E3afail%7E3aread%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">exn:fail:read</a></span> error. Setting this parameter allows
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DrRacket, for example, to open the file containing the error.</div></p><h4 x-source-module="(lib "parser-tools/br-parser-tools.scrbl")" x-source-pkg="br-parser-tools-doc" x-part-tag=""Lexer_Abbreviations_and_Macros"">1.2<tt> </tt><a name="(part._.Lexer_.Abbreviations_and_.Macros)"></a>Lexer Abbreviations and Macros</h4><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex..rkt)._char-set))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._char-set%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">char-set</a></span></span><span class="hspace"> </span><span class="RktVar">string</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="#%28tech._lexer._macro%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexer macro</span></a> that matches any character in <span class="RktVar">string</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._any-char))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-char%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">any-char</a></span></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="#%28tech._lexer._abbreviation%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexer abbreviation</span></a> that matches any character.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._any-string))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._any-string%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">any-string</a></span></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="#%28tech._lexer._abbreviation%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexer abbreviation</span></a> that matches any string.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._nothing))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._nothing%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">nothing</a></span></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="#%28tech._lexer._abbreviation%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexer abbreviation</span></a> that matches no string.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._alphabetic))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._alphabetic%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">alphabetic</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._lower-case))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lower-case%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">lower-case</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._upper-case))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._upper-case%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">upper-case</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._title-case))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._title-case%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">title-case</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._numeric))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._numeric%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">numeric</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._symbolic))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._symbolic%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">symbolic</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._punctuation))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._punctuation%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">punctuation</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._graphic))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._graphic%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">graphic</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._whitespace))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._whitespace%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">whitespace</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._blank))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._blank%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">blank</a></span></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(form._((lib._br-parser-tools/lex..rkt)._iso-control))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._iso-control%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">iso-control</a></span></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara"><a href="#%28tech._lexer._abbreviation%29" class="techoutside" data-pltdoc="x"><span class="techinside">Lexer abbreviations</span></a> that match <span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=characters.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._char-alphabetic%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">char-alphabetic?</a></span>
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characters, <span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=characters.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._char-lower-case%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">char-lower-case?</a></span> characters, etc.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex..rkt)._define-lex-abbrev))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-lex-abbrev%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">define-lex-abbrev</a></span></span><span class="hspace"> </span><span class="RktVar">id</span><span class="hspace"> </span><span class="RktVar">re</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Defines a <a href="#%28tech._lexer._abbreviation%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexer abbreviation</span></a> by associating a regular
|
|
expression to be used in place of the <span class="RktVar">id</span> in other
|
|
regular expression. The definition of name has the same scoping
|
|
properties as a other syntactic binding (e.g., it can be exported
|
|
from a module).</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex..rkt)._define-lex-abbrevs))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-lex-abbrevs%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">define-lex-abbrevs</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktVar">id</span><span class="hspace"> </span><span class="RktVar">re</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-lex-abbrev%29%29" class="RktStxLink" data-pltdoc="x">define-lex-abbrev</a></span>, but defines several <a href="#%28tech._lexer._abbreviation%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexer
|
|
abbreviations</span></a>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex..rkt)._define-lex-trans))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-lex-trans%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">define-lex-trans</a></span></span><span class="hspace"> </span><span class="RktVar">id</span><span class="hspace"> </span><span class="RktVar">trans-expr</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Defines a <a href="#%28tech._lexer._macro%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexer macro</span></a>, where <span class="RktVar">trans-expr</span> produces a
|
|
transformer procedure that takes one argument. When <span class="RktPn">(</span><span class="RktVar">id</span><span class="stt"> </span><span class="RktVar">datum</span><span class="stt"> </span><span class="RktMeta"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._......%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">...</a></span><span class="RktPn">)</span> appears as a regular expression, it is replaced with
|
|
the result of applying the transformer to the expression.</div></p><h4 x-source-module="(lib "parser-tools/br-parser-tools.scrbl")" x-source-pkg="br-parser-tools-doc" x-part-tag=""Lexer_SRE_Operators"">1.3<tt> </tt><a name="(part._.Lexer_.S.R.E_.Operators)"></a><a name="(mod-path._br-parser-tools/lex-sre)"></a>Lexer SRE Operators</h4><p><table cellspacing="0" cellpadding="0" class="defmodule"><tr><td align="left" colspan="2"><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="stt"> </span><a href="#%28mod-path._br-parser-tools%2Flex-sre%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">br-parser-tools/lex-sre</span></a><span class="RktPn">)</span></td></tr><tr><td align="left"> </td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <span class="stt">br-parser-tools-lib</span></span></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._*))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">*</a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Repetition of <span class="RktVar">re</span> sequence 0 or more times.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._+))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2B%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">+</a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Repetition of <span class="RktVar">re</span> sequence 1 or more times.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._~3f))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3f%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">?</a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Zero or one occurrence of <span class="RktVar">re</span> sequence.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._~3d))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3d%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">=</a></span></span><span class="hspace"> </span><span class="RktVar">n</span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Exactly <span class="RktVar">n</span> occurrences of <span class="RktVar">re</span> sequence, where
|
|
<span class="RktVar">n</span> must be a literal exact, non-negative number.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._~3e~3d))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3e~3d%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">>=</a></span></span><span class="hspace"> </span><span class="RktVar">n</span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">At least <span class="RktVar">n</span> occurrences of <span class="RktVar">re</span> sequence, where
|
|
<span class="RktVar">n</span> must be a literal exact, non-negative number.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._**))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%2A%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">**</a></span></span><span class="hspace"> </span><span class="RktVar">n</span><span class="hspace"> </span><span class="RktVar">m</span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Between <span class="RktVar">n</span> and <span class="RktVar">m</span> (inclusive) occurrences of
|
|
<span class="RktVar">re</span> sequence, where <span class="RktVar">n</span> must be a literal exact,
|
|
non-negative number, and <span class="RktVar">m</span> must be literally either
|
|
<span class="RktVal">#f</span>, <span class="RktVal">+inf.0</span>, or an exact, non-negative number; a
|
|
<span class="RktVal">#f</span> value for <span class="RktVar">m</span> is the same as <span class="RktVal">+inf.0</span>.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._or))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._or%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">or</a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Same as <span class="RktPn">(</span><span class="RktSym">union</span><span class="stt"> </span><span class="RktVar">re</span><span class="stt"> </span><span class="RktMeta"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._......%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">...</a></span><span class="RktPn">)</span>.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._~3a))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">:</a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._seq))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._seq%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">seq</a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Both forms concatenate the <span class="RktVar">re</span>s.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._~26))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~26%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">&</a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Intersects the <span class="RktVar">re</span>s.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._-))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._-%29%29" class="RktStxDef RktStxLink" data-pltdoc="x"><span class="nobreak">-</span></a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">The set difference of the <span class="RktVar">re</span>s.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._~7e))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~7e%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">~</a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Character-set complement, which each <span class="RktVar">re</span> must match exactly
|
|
one character.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-sre..rkt)._/))"></a><span title="Provided from: br-parser-tools/lex-sre | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2F%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">/</a></span></span><span class="hspace"> </span><span class="RktVar">char-or-string</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Character ranges, matching characters between successive pairs of
|
|
characters.</div></p><h4 x-source-module="(lib "parser-tools/br-parser-tools.scrbl")" x-source-pkg="br-parser-tools-doc" x-part-tag=""Lexer_Legacy_Operators"">1.4<tt> </tt><a name="(part._.Lexer_.Legacy_.Operators)"></a><a name="(mod-path._br-parser-tools/lex-plt-v200)"></a>Lexer Legacy Operators</h4><p><table cellspacing="0" cellpadding="0" class="defmodule"><tr><td align="left" colspan="2"><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="stt"> </span><a href="#%28mod-path._br-parser-tools%2Flex-plt-v200%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">br-parser-tools/lex-plt-v200</span></a><span class="RktPn">)</span></td></tr><tr><td align="left"> </td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <span class="stt">br-parser-tools-lib</span></span></td></tr></table></p><p><div class="SIntrapara">The <a href="#%28mod-path._br-parser-tools%2Flex-plt-v200%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">br-parser-tools/lex-plt-v200</span></a> module re-exports
|
|
<span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2A%29%29" class="RktStxLink" data-pltdoc="x">*</a></span>, <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2B%29%29" class="RktStxLink" data-pltdoc="x">+</a></span>, <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3f%29%29" class="RktStxLink" data-pltdoc="x">?</a></span>, and <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~26%29%29" class="RktStxLink" data-pltdoc="x">&</a></span> from
|
|
<a href="#%28mod-path._br-parser-tools%2Flex-sre%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">br-parser-tools/lex-sre</span></a>. It also re-exports
|
|
<span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._or%29%29" class="RktStxLink" data-pltdoc="x">:or</a></span> as <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._or%29%29" class="RktStxLink" data-pltdoc="x">:</a></span>, <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxLink" data-pltdoc="x">::</a></span> as <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~3a%29%29" class="RktStxLink" data-pltdoc="x">@</a></span>, <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~7e%29%29" class="RktStxLink" data-pltdoc="x">:~</a></span>
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as <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._~7e%29%29" class="RktStxLink" data-pltdoc="x">^</a></span>, and <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2F%29%29" class="RktStxLink" data-pltdoc="x">:/</a></span> as <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-sre..rkt%29._%2F%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-</span></a></span>.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-plt-v200..rkt)._epsilon))"></a><span title="Provided from: br-parser-tools/lex-plt-v200 | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-plt-v200..rkt%29._epsilon%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">epsilon</a></span></span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="#%28tech._lexer._macro%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexer macro</span></a> that matches an empty sequence.</div><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex-plt-v200..rkt)._~7e))"></a><span title="Provided from: br-parser-tools/lex-plt-v200 | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex-plt-v200..rkt%29._~7e%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">~</a></span></span><span class="hspace"> </span><span class="RktVar">re</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">The same as <span class="RktPn">(</span><span class="RktSym">complement</span><span class="stt"> </span><span class="RktVar">re</span><span class="stt"> </span><span class="RktMeta"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._......%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">...</a></span><span class="RktPn">)</span>.</div></p><h4 x-source-module="(lib "parser-tools/br-parser-tools.scrbl")" x-source-pkg="br-parser-tools-doc" x-part-tag=""Tokens"">1.5<tt> </tt><a name="(part._.Tokens)"></a>Tokens</h4><p>Each <span class="RktVar">action-expr</span> in a <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer%29%29" class="RktStxLink" data-pltdoc="x">lexer</a></span> form can produce any
|
|
kind of value, but for many purposes, producing a <a name="(tech._token)"></a><span style="font-style: italic">token</span>
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value is useful. Tokens are usually necessary for inter-operating with
|
|
a parser generated by <span class="RktSym">br-parser-tools/parser</span>, but tokens may not
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be the right choice when using <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._lexer%29%29" class="RktStxLink" data-pltdoc="x">lexer</a></span> in other situations.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex..rkt)._define-tokens))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-tokens%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">define-tokens</a></span></span><span class="hspace"> </span><span class="RktVar">group-id</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktVar">token-id</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Binds <span class="RktVar">group-id</span> to the group of tokens being defined. For
|
|
each <span class="RktVar">token-id</span>, a function
|
|
<span class="RktSym">token-</span><span class="RktVar">token-id</span> is created that takes any
|
|
value and puts it in a token record specific to <span class="RktVar">token-id</span>.
|
|
The token value is inspected using <span class="RktVar">token-id</span> and
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<span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._token-value%29%29" class="RktValLink" data-pltdoc="x">token-value</a></span>.</div></p><p>A token cannot be named <span class="RktSym">error</span>, since
|
|
<span class="RktSym">error</span> it has special use in the parser.</p><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._br-parser-tools/lex..rkt)._define-empty-tokens))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-empty-tokens%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">define-empty-tokens</a></span></span><span class="hspace"> </span><span class="RktVar">group-id</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktVar">token-id</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote><p>Like <span class="RktSym"><a href="#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-tokens%29%29" class="RktStxLink" data-pltdoc="x">define-tokens</a></span>, except a each token constructor
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|
<span class="RktSym">token-</span><span class="RktVar">token-id</span> takes no arguments and returns
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<span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=quote.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._quote%2529%2529&version=6.8.0.1" class="RktStxLink Sq" data-pltdoc="x">quote</a></span><span class="stt"> </span><span class="RktVar">token-id</span><span class="RktPn">)</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._br-parser-tools/lex..rkt)._token-name))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._token-name%29%29" class="RktValDef RktValLink" data-pltdoc="x">token-name</a></span></span><span class="hspace"> </span><span class="RktVar">t</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=symbols.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._symbol%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">symbol?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">t</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=data-structure-contracts.html%23%2528def._%2528%2528lib._racket%252Fcontract%252Fbase..rkt%2529._or%252Fc%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._token~3f%29%29" class="RktValLink" data-pltdoc="x">token?</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=symbols.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._symbol%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">symbol?</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the name of a token that is represented either by a symbol
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|
or a token structure.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._br-parser-tools/lex..rkt)._token-value))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._token-value%29%29" class="RktValDef RktValLink" data-pltdoc="x">token-value</a></span></span><span class="hspace"> </span><span class="RktVar">t</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=data-structure-contracts.html%23%2528def._%2528%2528lib._racket%252Fcontract%252Fprivate%252Fmisc..rkt%2529._any%252Fc%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">any/c</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">t</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=data-structure-contracts.html%23%2528def._%2528%2528lib._racket%252Fcontract%252Fbase..rkt%2529._or%252Fc%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._token~3f%29%29" class="RktValLink" data-pltdoc="x">token?</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=symbols.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._symbol%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">symbol?</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the value of a token that is represented either by a symbol
|
|
or a token structure, returning <span class="RktVal">#f</span> for a symbol token.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._br-parser-tools/lex..rkt)._token~3f))"></a><span title="Provided from: br-parser-tools/lex | Package: br-parser-tools-lib"><span class="RktSym"><a href="#%28def._%28%28lib._br-parser-tools%2Flex..rkt%29._token~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">token?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=booleans.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._boolean%7E3f%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/local-redirect/index.html?doc=reference&rel=data-structure-contracts.html%23%2528def._%2528%2528lib._racket%252Fcontract%252Fprivate%252Fmisc..rkt%2529._any%252Fc%2529%2529&version=6.8.0.1" class="RktValLink Sq" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktSym">val</span> is a
|
|
token structure, <span class="RktVal">#f</span> otherwise.</div></p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.8.0.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.8.0.1");">top</a></span><span class="navright"> <a href="index.html" title="backward to "Parser Tools: lex and yacc-style Parsing"" data-pltdoc="x">← prev</a> <a href="index.html" title="up to "Parser Tools: lex and yacc-style Parsing"" data-pltdoc="x">up</a> <a href="LALR_1__Parsers.html" title="forward to "2 LALR(1) Parsers"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html> |