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<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="fusion.view.filter_view"></a><a class="link" href="filter_view.html" title="filter_view">filter_view</a>
</h3></div></div></div>
<a name="fusion.view.filter_view.description"></a><h5>
<a name="id990509"></a>
<a class="link" href="filter_view.html#fusion.view.filter_view.description">Description</a>
</h5>
<p>
<code class="computeroutput"><span class="identifier">filter_view</span></code> is a view into
a subset of its underlying sequence's elements satisfying a given predicate
(an <a href="http://www.boost.org/libs/mpl/index.html" target="_top">MPL</a> metafunction).
The <code class="computeroutput"><span class="identifier">filter_view</span></code> presents
only those elements for which its predicate evaluates to <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span></code>.
</p>
<a name="fusion.view.filter_view.header"></a><h5>
<a name="id990560"></a>
<a class="link" href="filter_view.html#fusion.view.filter_view.header">Header</a>
</h5>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">view</span><span class="special">/</span><span class="identifier">filter_view</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">filter_view</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
</pre>
<a name="fusion.view.filter_view.synopsis"></a><h5>
<a name="id990668"></a>
<a class="link" href="filter_view.html#fusion.view.filter_view.synopsis">Synopsis</a>
</h5>
<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Sequence</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Pred</span><span class="special">></span>
<span class="keyword">struct</span> <span class="identifier">filter_view</span><span class="special">;</span>
</pre>
<a name="fusion.view.filter_view.template_parameters"></a><h5>
<a name="id990732"></a>
<a class="link" href="filter_view.html#fusion.view.filter_view.template_parameters">Template parameters</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Parameter
</p>
</th>
<th>
<p>
Description
</p>
</th>
<th>
<p>
Default
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">Sequence</span></code>
</p>
</td>
<td>
<p>
A <a class="link" href="../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward
Sequence</a>
</p>
</td>
<td>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">Pred</span></code>
</p>
</td>
<td>
<p>
Unary Metafunction returning an <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">bool_</span></code>
</p>
</td>
<td>
</td>
</tr>
</tbody>
</table></div>
<a name="fusion.view.filter_view.model_of"></a><h5>
<a name="id990864"></a>
<a class="link" href="filter_view.html#fusion.view.filter_view.model_of">Model of</a>
</h5>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a class="link" href="../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward Sequence</a>
</li>
<li class="listitem">
<a class="link" href="../sequence/concepts/associative_sequence.html" title="Associative Sequence">Associative
Sequence</a> if <code class="computeroutput"><span class="identifier">Sequence</span></code>
implements the <a class="link" href="../sequence/concepts/associative_sequence.html" title="Associative Sequence">Associative
Sequence</a> model.
</li>
</ul></div>
<div class="variablelist">
<p class="title"><b>Notation</b></p>
<dl>
<dt><span class="term"><code class="computeroutput"><span class="identifier">F</span></code></span></dt>
<dd><p>
A <code class="computeroutput"><span class="identifier">filter_view</span></code> type
</p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">f</span></code>, <code class="computeroutput"><span class="identifier">f2</span></code></span></dt>
<dd><p>
Instances of <code class="computeroutput"><span class="identifier">filter_view</span></code>
</p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">s</span></code></span></dt>
<dd><p>
A <a class="link" href="../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward
Sequence</a>
</p></dd>
</dl>
</div>
<a name="fusion.view.filter_view.expression_semantics"></a><h5>
<a name="id991008"></a>
<a class="link" href="filter_view.html#fusion.view.filter_view.expression_semantics">Expression Semantics</a>
</h5>
<p>
Semantics of an expression is defined only where it differs from, or is not
defined in the implemented models.
</p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Semantics
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">F</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
Creates a <code class="computeroutput"><span class="identifier">filter_view</span></code>
given a sequence, <code class="computeroutput"><span class="identifier">s</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">F</span><span class="special">(</span><span class="identifier">f</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
Copy constructs a <code class="computeroutput"><span class="identifier">filter_view</span></code>
from another <code class="computeroutput"><span class="identifier">filter_view</span></code>,
<code class="computeroutput"><span class="identifier">f</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">f</span> <span class="special">=</span>
<span class="identifier">f2</span></code>
</p>
</td>
<td>
<p>
Assigns to a <code class="computeroutput"><span class="identifier">filter_view</span></code>,
<code class="computeroutput"><span class="identifier">f</span></code>, from another
<code class="computeroutput"><span class="identifier">filter_view</span></code>, <code class="computeroutput"><span class="identifier">f2</span></code>.
</p>
</td>
</tr>
</tbody>
</table></div>
<a name="fusion.view.filter_view.example"></a><h5>
<a name="id991232"></a>
<a class="link" href="filter_view.html#fusion.view.filter_view.example">Example</a>
</h5>
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">_</span><span class="special">;</span>
<span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">not_</span><span class="special">;</span>
<span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_class</span><span class="special">;</span>
<span class="keyword">typedef</span> <a class="link" href="../container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">,</span> <span class="keyword">char</span><span class="special">,</span> <span class="keyword">long</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">,</span> <span class="keyword">double</span><span class="special">></span> <span class="identifier">vector_type</span><span class="special">;</span>
<span class="identifier">vector_type</span> <span class="identifier">v</span><span class="special">(</span><span class="string">"a-string"</span><span class="special">,</span> <span class="char">'@'</span><span class="special">,</span> <span class="number">987654</span><span class="special">,</span> <span class="keyword">true</span><span class="special">,</span> <span class="number">6.6</span><span class="special">);</span>
<span class="identifier">filter_view</span><span class="special"><</span><span class="identifier">vector_type</span> <span class="keyword">const</span><span class="special">,</span> <span class="identifier">not_</span><span class="special"><</span><span class="identifier">is_class</span><span class="special"><</span><span class="identifier">_</span><span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="identifier">view</span><span class="special">(</span><span class="identifier">v</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">view</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
</pre>
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<td align="right"><div class="copyright-footer">Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias
Schwinger<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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