<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Struct template local</title> <link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../../xpressive/reference.html#header.boost.xpressive.regex_actions_hpp" title="Header <boost/xpressive/regex_actions.hpp>"> <link rel="prev" href="function.html" title="Struct template function"> <link rel="next" href="placeholder.html" title="Struct template placeholder"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> <td align="center"><a href="../../../../index.html">Home</a></td> <td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="function.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../xpressive/reference.html#header.boost.xpressive.regex_actions_hpp"><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="placeholder.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="refentry"> <a name="boost.xpressive.local"></a><div class="titlepage"></div> <div class="refnamediv"> <h2><span class="refentrytitle">Struct template local</span></h2> <p>boost::xpressive::local — <code class="computeroutput">local<></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> </div> <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../xpressive/reference.html#header.boost.xpressive.regex_actions_hpp" title="Header <boost/xpressive/regex_actions.hpp>">boost/xpressive/regex_actions.hpp</a>> </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> <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"><</span> <span class="identifier">reference_wrapper</span><span class="special"><</span> <span class="identifier">T</span> <span class="special">></span> <span class="special">></span> <span class="special">{</span> <span class="comment">// <a class="link" href="local.html#boost.xpressive.localconstruct-copy-destruct">construct/copy/destruct</a></span> <a class="link" href="local.html#idm45506840479040-bb"><span class="identifier">local</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span> <span class="keyword">explicit</span> <a class="link" href="local.html#idm45506840477984-bb"><span class="identifier">local</span></a><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">)</span><span class="special">;</span> <span class="comment">// <a class="link" href="local.html#idm45506840482576-bb">public member functions</a></span> <span class="identifier">T</span> <span class="special">&</span> <a class="link" href="local.html#idm45506840482016-bb"><span class="identifier">get</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span> <span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&</span> <a class="link" href="local.html#idm45506840480864-bb"><span class="identifier">get</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="special">}</span><span class="special">;</span></pre></div> <div class="refsect1"> <a name="idm45555020831488"></a><h2>Description</h2> <p> Below is an example of how to use <code class="computeroutput">local<></code> in semantic actions.</p> <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> <span class="identifier">local</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">i</span><span class="special">(</span><span class="number">0</span><span class="special">)</span><span class="special">;</span> <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> <span class="comment">// count the exciting digits, but not the</span> <span class="comment">// questionable ones.</span> <span class="identifier">sregex</span> <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">>></span> <span class="char">'!'</span> <span class="special">)</span><span class="special">;</span> <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> <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> </pre> <p> </p> <div class="note"><table border="0" summary="Note"> <tr> <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../doc/src/images/note.png"></td> <th align="left">Note</th> </tr> <tr><td align="left" valign="top"><p>As the name "local" suggests, <code class="computeroutput">local<></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<>'s</code> lifetime, and any regex objects still holding the <code class="computeroutput">local<></code> will be left with a dangling reference. </p></td></tr> </table></div> <p> </p> <div class="refsect2"> <a name="idm45555020792528"></a><h3>Template Parameters</h3> <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> <pre class="literallayout"><span class="keyword">typename</span> T</pre> <p>The type of the local variable.</p> </li></ol></div> </div> <div class="refsect2"> <a name="idm45555020789392"></a><h3> <a name="boost.xpressive.localconstruct-copy-destruct"></a><code class="computeroutput">local</code> public construct/copy/destruct</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <pre class="literallayout"><a name="idm45506840479040-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> <li class="listitem"> <pre class="literallayout"><span class="keyword">explicit</span> <a name="idm45506840477984-bb"></a><span class="identifier">local</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&</span> t<span class="special">)</span><span class="special">;</span></pre>Store a default-constructed value of type <code class="computeroutput">T</code>. <p> </p> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody><tr> <td><p><span class="term">Parameters:</span></p></td> <td><div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody><tr> <td><p><span class="term"><code class="computeroutput">t</code></span></p></td> <td><p>The initial value. </p></td> </tr></tbody> </table></div></td> </tr></tbody> </table></div> </li> </ol></div> </div> <div class="refsect2"> <a name="idm45555020772240"></a><h3> <a name="idm45506840482576-bb"></a><code class="computeroutput">local</code> public member functions</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <pre class="literallayout"><span class="identifier">T</span> <span class="special">&</span> <a name="idm45506840482016-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> <li class="listitem"> <pre class="literallayout"><span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&</span> <a name="idm45506840480864-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> <p>This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. </p> </li> </ol></div> </div> </div> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2007 Eric Niebler<p> Distributed under the Boost Software License, Version 1.0. (See accompanying 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>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="function.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../xpressive/reference.html#header.boost.xpressive.regex_actions_hpp"><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="placeholder.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>