libs/spirit/doc/html/spirit/qi/reference/directive/matches.html

   1 <html>
   2 <head>
   3 <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
   4 <title>Directive Testing if Parser Succeeded (matches[])</title>
   5 <link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css">
   6 <meta name="generator" content="DocBook XSL Stylesheets V1.78.1">
   7 <link rel="home" href="../../../../index.html" title="Spirit 2.5.2">
   8 <link rel="up" href="../directive.html" title="Parser Directives">
   9 <link rel="prev" href="repeat.html" title="Repetition Parser Directive (repeat[])">
  10 <link rel="next" href="skip.html" title="Parser Directive Re-Establishing Skipping (skip[])">
  11 </head>
  12 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
  13 <table cellpadding="2" width="100%"><tr>
  14 <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td>
  15 <td align="center"><a href="../../../../../../../../index.html">Home</a></td>
  16 <td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td>
  17 <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
  18 <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
  19 <td align="center"><a href="../../../../../../../../more/index.htm">More</a></td>
  20 </tr></table>
  21 <hr>
  22 <div class="spirit-nav">
  23 <a accesskey="p" href="repeat.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../directive.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="skip.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a>
  24 </div>
  25 <div class="section">
  26 <div class="titlepage"><div><div><h5 class="title">
  27 <a name="spirit.qi.reference.directive.matches"></a><a class="link" href="matches.html" title="Directive Testing if Parser Succeeded (matches[])">Directive
  28           Testing if Parser Succeeded (<code class="computeroutput"><span class="identifier">matches</span><span class="special">[]</span></code>)</a>
  29 </h5></div></div></div>
  30 <h6>
  31 <a name="spirit.qi.reference.directive.matches.h0"></a>
  32             <span class="phrase"><a name="spirit.qi.reference.directive.matches.description"></a></span><a class="link" href="matches.html#spirit.qi.reference.directive.matches.description">Description</a>
  33           </h6>
  34 <p>
  35             The <code class="computeroutput"><span class="identifier">matches</span><span class="special">[]</span></code>
  36             directive executes the embedded parser and returns whether it succeeded
  37             matching.
  38           </p>
  39 <h6>
  40 <a name="spirit.qi.reference.directive.matches.h1"></a>
  41             <span class="phrase"><a name="spirit.qi.reference.directive.matches.header"></a></span><a class="link" href="matches.html#spirit.qi.reference.directive.matches.header">Header</a>
  42           </h6>
  43 <pre class="programlisting"><span class="comment">// forwards to &lt;boost/spirit/home/qi/directive/matches.hpp&gt;</span>
  44 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">qi_matches</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  45 </pre>
  46 <p>
  47             Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>.
  48           </p>
  49 <h6>
  50 <a name="spirit.qi.reference.directive.matches.h2"></a>
  51             <span class="phrase"><a name="spirit.qi.reference.directive.matches.namespace"></a></span><a class="link" href="matches.html#spirit.qi.reference.directive.matches.namespace">Namespace</a>
  52           </h6>
  53 <div class="informaltable"><table class="table">
  54 <colgroup><col></colgroup>
  55 <thead><tr><th>
  56                     <p>
  57                       Name
  58                     </p>
  59                   </th></tr></thead>
  60 <tbody><tr><td>
  61                     <p>
  62                       <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">matches</span> <span class="comment">//
  63                       alias: boost::spirit::qi::matches</span></code>
  64                     </p>
  65                   </td></tr></tbody>
  66 </table></div>
  67 <h6>
  68 <a name="spirit.qi.reference.directive.matches.h3"></a>
  69             <span class="phrase"><a name="spirit.qi.reference.directive.matches.model_of"></a></span><a class="link" href="matches.html#spirit.qi.reference.directive.matches.model_of">Model
  70             of</a>
  71           </h6>
  72 <div class="blockquote"><blockquote class="blockquote"><p>
  73               <a class="link" href="../parser_concepts/unaryparser.html" title="UnaryParser"><code class="computeroutput"><span class="identifier">UnaryParser</span></code></a>
  74             </p></blockquote></div>
  75 <div class="variablelist">
  76 <p class="title"><b>Notation</b></p>
  77 <dl class="variablelist">
  78 <dt><span class="term"><code class="computeroutput"><span class="identifier">a</span></code></span></dt>
  79 <dd><p>
  80                   A <a class="link" href="../parser_concepts/parser.html" title="Parser"><code class="computeroutput"><span class="identifier">Parser</span></code></a>.
  81                 </p></dd>
  82 </dl>
  83 </div>
  84 <h6>
  85 <a name="spirit.qi.reference.directive.matches.h4"></a>
  86             <span class="phrase"><a name="spirit.qi.reference.directive.matches.expression_semantics"></a></span><a class="link" href="matches.html#spirit.qi.reference.directive.matches.expression_semantics">Expression
  87             Semantics</a>
  88           </h6>
  89 <p>
  90             Semantics of an expression is defined only where it differs from, or
  91             is not defined in <a class="link" href="../parser_concepts/unaryparser.html" title="UnaryParser"><code class="computeroutput"><span class="identifier">UnaryParser</span></code></a>.
  92           </p>
  93 <div class="informaltable"><table class="table">
  94 <colgroup>
  95 <col>
  96 <col>
  97 </colgroup>
  98 <thead><tr>
  99 <th>
 100                     <p>
 101                       Expression
 102                     </p>
 103                   </th>
 104 <th>
 105                     <p>
 106                       Semantics
 107                     </p>
 108                   </th>
 109 </tr></thead>
 110 <tbody><tr>
 111 <td>
 112                     <p>
 113                       <code class="computeroutput"><span class="identifier">matches</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code>
 114                     </p>
 115                   </td>
 116 <td>
 117                     <p>
 118                       Execute the subject parser <code class="computeroutput"><span class="identifier">a</span></code>,
 119                       and return as its attribute whether it succeeded. The directive
 120                       itself does always succeed.
 121                     </p>
 122                   </td>
 123 </tr></tbody>
 124 </table></div>
 125 <h6>
 126 <a name="spirit.qi.reference.directive.matches.h5"></a>
 127             <span class="phrase"><a name="spirit.qi.reference.directive.matches.attributes"></a></span><a class="link" href="matches.html#spirit.qi.reference.directive.matches.attributes">Attributes</a>
 128           </h6>
 129 <div class="informaltable"><table class="table">
 130 <colgroup>
 131 <col>
 132 <col>
 133 </colgroup>
 134 <thead><tr>
 135 <th>
 136                     <p>
 137                       Expression
 138                     </p>
 139                   </th>
 140 <th>
 141                     <p>
 142                       Attribute
 143                     </p>
 144                   </th>
 145 </tr></thead>
 146 <tbody><tr>
 147 <td>
 148                     <p>
 149                       <code class="computeroutput"><span class="identifier">matches</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code>
 150                     </p>
 151                   </td>
 152 <td>
 153                     <p>
 154                       <code class="computeroutput"><span class="keyword">bool</span></code>
 155                     </p>
 156                   </td>
 157 </tr></tbody>
 158 </table></div>
 159 <h6>
 160 <a name="spirit.qi.reference.directive.matches.h6"></a>
 161             <span class="phrase"><a name="spirit.qi.reference.directive.matches.complexity"></a></span><a class="link" href="matches.html#spirit.qi.reference.directive.matches.complexity">Complexity</a>
 162           </h6>
 163 <div class="blockquote"><blockquote class="blockquote"><p>
 164               The complexity is defined by the complexity of the subject parser,
 165               <code class="computeroutput"><span class="identifier">a</span></code>
 166             </p></blockquote></div>
 167 <h6>
 168 <a name="spirit.qi.reference.directive.matches.h7"></a>
 169             <span class="phrase"><a name="spirit.qi.reference.directive.matches.example"></a></span><a class="link" href="matches.html#spirit.qi.reference.directive.matches.example">Example</a>
 170           </h6>
 171 <div class="note"><table border="0" summary="Note">
 172 <tr>
 173 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td>
 174 <th align="left">Note</th>
 175 </tr>
 176 <tr><td align="left" valign="top"><p>
 177               The test harness for the example(s) below is presented in the <a class="link" href="../basics.html#spirit.qi.reference.basics.examples">Basics Examples</a>
 178               section.
 179             </p></td></tr>
 180 </table></div>
 181 <p>
 182             Some using declarations:
 183           </p>
 184 <p>
 185 </p>
 186 <pre class="programlisting"><span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">matches</span><span class="special">;</span>
 187 <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">int_</span><span class="special">;</span>
 188 </pre>
 189 <p>
 190           </p>
 191 <p>
 192             This parser tries to match an <code class="computeroutput"><span class="keyword">int</span></code>
 193             and returns <code class="computeroutput"><span class="keyword">true</span></code> a its attribute
 194             as it succeeded matching:
 195           </p>
 196 <p>
 197 </p>
 198 <pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">result</span> <span class="special">=</span> <span class="keyword">false</span><span class="special">;</span>
 199 <span class="identifier">test_parser_attr</span><span class="special">(</span><span class="string">"345"</span><span class="special">,</span> <span class="identifier">matches</span><span class="special">[</span><span class="identifier">int_</span><span class="special">],</span> <span class="identifier">result</span><span class="special">);</span>
 200 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">boolalpha</span> <span class="special">&lt;&lt;</span> <span class="identifier">result</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// should print: true</span>
 201 </pre>
 202 <p>
 203           </p>
 204 <p>
 205             This parser tries to match an <code class="computeroutput"><span class="keyword">int</span></code>
 206             as well and returns <code class="computeroutput"><span class="keyword">false</span></code>
 207             as its attribute as it fails matching:
 208           </p>
 209 <p>
 210 </p>
 211 <pre class="programlisting"><span class="identifier">result</span> <span class="special">=</span> <span class="keyword">true</span><span class="special">;</span>
 212 <span class="identifier">test_parser_attr</span><span class="special">(</span><span class="string">"abc"</span><span class="special">,</span> <span class="identifier">matches</span><span class="special">[</span><span class="identifier">int_</span><span class="special">],</span> <span class="identifier">result</span><span class="special">);</span>
 213 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">boolalpha</span> <span class="special">&lt;&lt;</span> <span class="identifier">result</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// should print: false</span>
 214 </pre>
 215 <p>
 216           </p>
 217 </div>
 218 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 219 <td align="left"></td>
 220 <td align="right"><div class="copyright-footer">Copyright &#169; 2001-2011 Joel de Guzman, Hartmut Kaiser<p>
 221         Distributed under the Boost Software License, Version 1.0. (See accompanying
 222         file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
 223       </p>
 224 </div></td>
 225 </tr></table>
 226 <hr>
 227 <div class="spirit-nav">
 228 <a accesskey="p" href="repeat.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../directive.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="skip.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a>
 229 </div>
 230 </body>
 231 </html>