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  25 <div class="refentry">
  26 <a name="boost.xpressive.local"></a><div class="titlepage"></div>
  27 <div class="refnamediv">
  28 <h2><span class="refentrytitle">Struct template local</span></h2>
  29 <p>boost::xpressive::local &#8212; <code class="computeroutput">local&lt;&gt;</code> is a lazy wrapper for a reference to a value that is stored within the local itself. It is for use within xpressive semantic actions. </p>
  30 </div>
  31 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  32 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../xpressive/reference.html#header.boost.xpressive.regex_actions_hpp" title="Header &lt;boost/xpressive/regex_actions.hpp&gt;">boost/xpressive/regex_actions.hpp</a>&gt;
  33
  34 </span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span>
  35 <span class="keyword">struct</span> <a class="link" href="local.html" title="Struct template local">local</a> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">proto</span><span class="special">::</span><span class="identifier">terminal</span><span class="special">::</span><span class="identifier">type</span><span class="special">&lt;</span> <span class="identifier">reference_wrapper</span><span class="special">&lt;</span> <span class="identifier">T</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">{</span>
  36   <span class="comment">// <a class="link" href="local.html#boost.xpressive.localconstruct-copy-destruct">construct/copy/destruct</a></span>
  37   <a class="link" href="local.html#idp355264672-bb"><span class="identifier">local</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  38   <span class="keyword">explicit</span> <a class="link" href="local.html#idp355265728-bb"><span class="identifier">local</span></a><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  39
  40   <span class="comment">// <a class="link" href="local.html#idp355261136-bb">public member functions</a></span>
  41   <span class="identifier">T</span> <span class="special">&amp;</span> <a class="link" href="local.html#idp355261696-bb"><span class="identifier">get</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  42   <span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&amp;</span> <a class="link" href="local.html#idp355262848-bb"><span class="identifier">get</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  43 <span class="special">}</span><span class="special">;</span></pre></div>
  44 <div class="refsect1">
  45 <a name="idp533982976"></a><h2>Description</h2>
  46 <p>
  47 Below is an example of how to use <code class="computeroutput">local&lt;&gt;</code> in semantic actions.</p>
  48 <pre class="programlisting"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">xpressive</span><span class="special">;</span>
  49 <a class="link" href="local.html" title="Struct template local">local&lt;int&gt;</a> <span class="identifier">i</span><span class="special">(</span><span class="number">0</span><span class="special">)</span><span class="special">;</span>
  50 <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">str</span><span class="special">(</span><span class="string">"1!2!3?"</span><span class="special">)</span><span class="special">;</span>
  51 <span class="comment">// count the exciting digits, but not the</span>
  52 <span class="comment">// questionable ones.</span>
  53 <a class="link" href="basic_regex.html" title="Struct template basic_regex">sregex</a> <span class="identifier">rex</span> <span class="special">=</span> <span class="special">+</span><span class="special">(</span> <span class="identifier">_d</span> <span class="special">[</span> <span class="special">++</span><span class="identifier">i</span> <span class="special">]</span> <span class="special">&gt;&gt;</span> <span class="char">'!'</span> <span class="special">)</span><span class="special">;</span>
  54 <span class="identifier">regex_search</span><span class="special">(</span><span class="identifier">str</span><span class="special">,</span> <span class="identifier">rex</span><span class="special">)</span><span class="special">;</span>
  55 <span class="identifier">assert</span><span class="special">(</span> <span class="identifier">i</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="special">)</span> <span class="special">==</span> <span class="number">2</span> <span class="special">)</span><span class="special">;</span>
  56 </pre>
  57 <p> </p>
  58 <div class="note"><table border="0" summary="Note">
  59 <tr>
  60 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../doc/src/images/note.png"></td>
  61 <th align="left">Note</th>
  62 </tr>
  63 <tr><td align="left" valign="top"><p>As the name "local" suggests, <code class="computeroutput">local&lt;&gt;</code> objects and the regexes that refer to them should never leave the local scope. The value stored within the local object will be destroyed at the end of the <code class="computeroutput">local&lt;&gt;'s</code> lifetime, and any regex objects still holding the <code class="computeroutput">local&lt;&gt;</code> will be left with a dangling reference. </p></td></tr>
  64 </table></div>
  65 <p>
  66 </p>
  67 <div class="refsect2">
  68 <a name="idp534020544"></a><h3>Template Parameters</h3>
  69 <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
  70 <pre class="literallayout"><span class="keyword">typename</span> T</pre>
  71 <p>The type of the local variable.</p>
  72 </li></ol></div>
  73 </div>
  74 <div class="refsect2">
  75 <a name="idp534023680"></a><h3>
  76 <a name="boost.xpressive.localconstruct-copy-destruct"></a><code class="computeroutput">local</code>
  77         public
  78        construct/copy/destruct</h3>
  79 <div class="orderedlist"><ol class="orderedlist" type="1">
  80 <li class="listitem">
  81 <pre class="literallayout"><a name="idp355264672-bb"></a><span class="identifier">local</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>Store a default-constructed value of type <code class="computeroutput">T</code>. </li>
  82 <li class="listitem">
  83 <pre class="literallayout"><span class="keyword">explicit</span> <a name="idp355265728-bb"></a><span class="identifier">local</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&amp;</span> t<span class="special">)</span><span class="special">;</span></pre>Store a default-constructed value of type <code class="computeroutput">T</code>. <p>
  84 </p>
  85 <div class="variablelist"><table border="0" class="variablelist compact">
  86 <colgroup>
  87 <col align="left" valign="top">
  88 <col>
  89 </colgroup>
  90 <tbody><tr>
  91 <td><p><span class="term">Parameters:</span></p></td>
  92 <td><div class="variablelist"><table border="0" class="variablelist compact">
  93 <colgroup>
  94 <col align="left" valign="top">
  95 <col>
  96 </colgroup>
  97 <tbody><tr>
  98 <td><p><span class="term"><code class="computeroutput">t</code></span></p></td>
  99 <td><p>The initial value. </p></td>
 100 </tr></tbody>
 101 </table></div></td>
 102 </tr></tbody>
 103 </table></div>
 104 </li>
 105 </ol></div>
 106 </div>
 107 <div class="refsect2">
 108 <a name="idp534040768"></a><h3>
 109 <a name="idp355261136-bb"></a><code class="computeroutput">local</code> public member functions</h3>
 110 <div class="orderedlist"><ol class="orderedlist" type="1">
 111 <li class="listitem">
 112 <pre class="literallayout"><span class="identifier">T</span> <span class="special">&amp;</span> <a name="idp355261696-bb"></a><span class="identifier">get</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>Fetch the wrapped value. </li>
 113 <li class="listitem">
 114 <pre class="literallayout"><span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&amp;</span> <a name="idp355262848-bb"></a><span class="identifier">get</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 115 <p>This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. </p>
 116 </li>
 117 </ol></div>
 118 </div>
 119 </div>
 120 </div>
 121 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 122 <td align="left"></td>
 123 <td align="right"><div class="copyright-footer">Copyright &#169; 2007 Eric Niebler<p>
 124         Distributed under the Boost Software License, Version 1.0. (See accompanying
 125         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>)
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