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boost_fusion/doc/html/fusion/sequences/intrinsics/metafunctions/has_key.html
Tobias Schwinger ca6f831b96 adds documentation for functional module 
[SVN r36959]
2007-02-15 23:11:24 +00:00

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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>has_key</title>
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<div class="section" lang="en">
<div class="titlepage"><div><div><h5 class="title">
<a name="fusion.sequences.intrinsics.metafunctions.has_key"></a><a href="has_key.html" title="has_key">has_key</a></h5></div></div></div>
<a name="fusion.sequences.intrinsics.metafunctions.has_key.description"></a><h6>
<a name="id1035711"></a>
<a href="has_key.html#fusion.sequences.intrinsics.metafunctions.has_key.description">Description</a>
</h6>
<p>
Returns the result type of <a href="../functions/has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">has_key</span></code></a>.
</p>
<a name="fusion.sequences.intrinsics.metafunctions.has_key.synopsis"></a><h6>
<a name="id1035752"></a>
<a href="has_key.html#fusion.sequences.intrinsics.metafunctions.has_key.synopsis">Synopsis</a>
</h6>
<pre class="programlisting">
<span class="keyword">template</span><span class="special">&lt;</span>
<span class="keyword">typename</span> <span class="identifier">Seq</span><span class="special">,</span>
<span class="keyword">typename</span> <span class="identifier">Key</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">has_key</span>
<span class="special">{</span>
<span class="keyword">typedef</span> <span class="emphasis"><em>unspecified</em></span> <span class="identifier">type</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<div class="table">
<a name="id1035854"></a><p class="title"><b>Table 1.29. Parameters</b></p>
<table class="table" summary="Parameters">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>Parameter</th>
<th>Requirement</th>
<th>Description</th>
</tr></thead>
<tbody>
<tr>
<td><code class="computeroutput"><span class="identifier">Seq</span></code></td>
<td>A
model of <a href="../../concepts/forward_sequence.html" title="Forward
Sequence">Forward
Sequence</a>
</td>
<td>Argument sequence</td>
</tr>
<tr>
<td><code class="computeroutput"><span class="identifier">Key</span></code></td>
<td>Any
type</td>
<td>Key type</td>
</tr>
</tbody>
</table>
</div>
<a name="fusion.sequences.intrinsics.metafunctions.has_key.expression_semantics"></a><h6>
<a name="id1035940"></a>
<a href="has_key.html#fusion.sequences.intrinsics.metafunctions.has_key.expression_semantics">Expression
Semantics</a>
</h6>
<pre class="programlisting">
<span class="identifier">result_of</span><span class="special">::</span><span class="identifier">has_key</span><span class="special">&lt;</span><span class="identifier">Seq</span><span class="special">,</span> <span class="identifier">Key</span><span class="special">&gt;::</span><span class="identifier">type</span>
</pre>
<p>
<span class="bold"><strong>Return type</strong></span>: An <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL
Integral Constant</a>.
</p>
<p>
<span class="bold"><strong>Semantics</strong></span>: Returns <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span></code>
if <code class="computeroutput"><span class="identifier">Seq</span></code> contains an element
with key type <code class="computeroutput"><span class="identifier">Key</span></code>, returns
<code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">false_</span></code> otherwise.
</p>
<a name="fusion.sequences.intrinsics.metafunctions.has_key.header"></a><h6>
<a name="id1036090"></a>
<a href="has_key.html#fusion.sequences.intrinsics.metafunctions.has_key.header">Header</a>
</h6>
<pre class="programlisting">
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">sequence</span><span class="special">/</span><span class="identifier">intrinsic</span><span class="special">/</span><span class="identifier">has_key</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<a name="fusion.sequences.intrinsics.metafunctions.has_key.example"></a><h6>
<a name="id1036183"></a>
<a href="has_key.html#fusion.sequences.intrinsics.metafunctions.has_key.example">Example</a>
</h6>
<pre class="programlisting">
<span class="keyword">typedef</span> <a href="../../containers/map.html" title="map"><code class="computeroutput"><span class="identifier">map</span></code></a><span class="special">&lt;</span><a href="../../../support/pair.html" title="pair"><code class="computeroutput"><span class="identifier">pair</span></code></a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">char</span><span class="special">&gt;,</span> <a href="../../../support/pair.html" title="pair"><code class="computeroutput"><span class="identifier">pair</span></code></a><span class="special">&lt;</span><span class="keyword">char</span><span class="special">,</span> <span class="keyword">char</span><span class="special">&gt;,</span> <a href="../../../support/pair.html" title="pair"><code class="computeroutput"><span class="identifier">pair</span></code></a><span class="special">&lt;</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">char</span><span class="special">&gt;</span> <span class="special">&gt;</span> <span class="identifier">mymap</span><span class="special">;</span>
<span class="identifier">BOOST_MPL_ASSERT</span><span class="special">((</span><a href="has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">has_key</span></code></a><span class="special">&lt;</span><span class="identifier">mymap</span><span class="special">,</span> <span class="keyword">int</span><span class="special">&gt;));</span>
<span class="identifier">BOOST_MPL_ASSERT_NOT</span><span class="special">((</span><a href="has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">has_key</span></code></a><span class="special">&lt;</span><span class="identifier">mymap</span><span class="special">,</span> <span class="keyword">void</span><span class="special">*&gt;));</span>
</pre>
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