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| <h2><span class="refentrytitle">Struct mark_tag</span></h2> |
| <p>boost::xpressive::mark_tag — Sub-match placeholder type, used to create named captures in static regexes. </p> |
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| <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_primitives_hpp" title="Header <boost/xpressive/regex_primitives.hpp>">boost/xpressive/regex_primitives.hpp</a>> |
| |
| </span> |
| <span class="keyword">struct</span> <a class="link" href="mark_tag.html" title="Struct mark_tag">mark_tag</a> <span class="special">{</span> |
| <span class="comment">// <a class="link" href="mark_tag.html#boost.xpressive.mark_tagconstruct-copy-destruct">construct/copy/destruct</a></span> |
| <a class="link" href="mark_tag.html#id1538848-bb"><span class="identifier">mark_tag</span></a><span class="special">(</span><span class="keyword">int</span><span class="special">)</span><span class="special">;</span> |
| |
| <span class="comment">// <a class="link" href="mark_tag.html#id1538825-bb">private static functions</a></span> |
| <span class="keyword">static</span> <span class="emphasis"><em><span class="identifier">unspecified</span></em></span> <a class="link" href="mark_tag.html#id1538829-bb"><span class="identifier">make_tag</span></a><span class="special">(</span><span class="keyword">int</span><span class="special">)</span><span class="special">;</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id3186365"></a><h2>Description</h2> |
| <p><code class="computeroutput">mark_tag</code> is the type of the global sub-match placeholders <code class="computeroutput">s0</code>, <code class="computeroutput">s1</code>, etc.. You can use the <code class="computeroutput">mark_tag</code> type to create your own sub-match placeholders with more meaningful names. This is roughly equivalent to the "named capture" feature of dynamic regular expressions.</p> |
| <p>To create a named sub-match placeholder, initialize it with a unique integer. The integer must only be unique within the regex in which the placeholder is used. Then you can use it within static regexes to created sub-matches by assigning a sub-expression to it, or to refer back to already created sub-matches.</p> |
| <pre class="programlisting"> <span class="identifier">mark_tag</span> <span class="identifier">number</span><span class="special">(</span><span class="number">1</span><span class="special">)</span><span class="special">;</span> <span class="comment">// "number" is now equivalent to "s1"</span> |
| <span class="comment">// Match a number, followed by a space and the same number again</span> |
| <span class="identifier">sregex</span> <span class="identifier">rx</span> <span class="special">=</span> <span class="special">(</span><span class="identifier">number</span> <span class="special">=</span> <span class="special">+</span><span class="identifier">_d</span><span class="special">)</span> <span class="special">>></span> <span class="char">' '</span> <span class="special">>></span> <span class="identifier">number</span><span class="special">;</span> |
| </pre> |
| <p>After a successful <code class="computeroutput">regex_match()</code> or <code class="computeroutput">regex_search()</code>, the sub-match placeholder can be used to index into the <code class="computeroutput">match_results<></code> object to retrieve the corresponding sub-match. </p> |
| <div class="refsect2"> |
| <a name="id3186544"></a><h3> |
| <a name="boost.xpressive.mark_tagconstruct-copy-destruct"></a><code class="computeroutput">mark_tag</code> |
| public |
| construct/copy/destruct</h3> |
| <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> |
| <pre class="literallayout"><a name="id1538848-bb"></a><span class="identifier">mark_tag</span><span class="special">(</span><span class="keyword">int</span> mark_nbr<span class="special">)</span><span class="special">;</span></pre>Initialize a mark_tag placeholder. <p> |
| |
| </p> |
| <div class="variablelist"><table border="0"> |
| <col align="left" valign="top"> |
| <tbody> |
| <tr> |
| <td><p><span class="term">Parameters:</span></p></td> |
| <td><div class="variablelist"><table border="0"> |
| <col align="left" valign="top"> |
| <tbody><tr> |
| <td><p><span class="term"><code class="computeroutput">mark_nbr</code></span></p></td> |
| <td><p>An integer that uniquely identifies this <code class="computeroutput">mark_tag</code> within the static regexes in which this <code class="computeroutput">mark_tag</code> will be used. </p></td> |
| </tr></tbody> |
| </table></div></td> |
| </tr> |
| <tr> |
| <td><p><span class="term">Requires:</span></p></td> |
| <td><p><code class="computeroutput">mark_nbr > 0</code> </p></td> |
| </tr> |
| </tbody> |
| </table></div> |
| </li></ol></div> |
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| <div class="refsect2"> |
| <a name="id3186651"></a><h3> |
| <a name="id1538825-bb"></a><code class="computeroutput">mark_tag</code> private static functions</h3> |
| <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><pre class="literallayout"><span class="keyword">static</span> <span class="emphasis"><em><span class="identifier">unspecified</span></em></span> <a name="id1538829-bb"></a><span class="identifier">make_tag</span><span class="special">(</span><span class="keyword">int</span> mark_nbr<span class="special">)</span><span class="special">;</span></pre></li></ol></div> |
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| <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>) |
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