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| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="fusion.algorithm.query.functions.find_if"></a><a class="link" href="find_if.html" title="find_if">find_if</a> |
| </h5></div></div></div> |
| <p> |
| Finds the first element within a sequence with a type for which a given |
| <a href="http://www.boost.org/libs/mpl/doc/refmanual/lambda-expression.html" target="_top">MPL |
| Lambda Expression</a> evaluates to <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span></code>. |
| </p> |
| <a name="fusion.algorithm.query.functions.find_if.description"></a><h6> |
| <a name="id1008465"></a> |
| <a class="link" href="find_if.html#fusion.algorithm.query.functions.find_if.description">Description</a> |
| </h6> |
| <a name="fusion.algorithm.query.functions.find_if.synopsis"></a><h6> |
| <a name="id1008478"></a> |
| <a class="link" href="find_if.html#fusion.algorithm.query.functions.find_if.synopsis">Synopsis</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> |
| <span class="keyword">typename</span> <span class="identifier">F</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">Sequence</span> |
| <span class="special">></span> |
| <span class="emphasis"><em>unspecified</em></span> <span class="identifier">find_if</span><span class="special">(</span><span class="identifier">Sequence</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">seq</span><span class="special">);</span> |
| |
| <span class="keyword">template</span><span class="special"><</span> |
| <span class="keyword">typename</span> <span class="identifier">F</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">Sequence</span> |
| <span class="special">></span> |
| <span class="emphasis"><em>unspecified</em></span> <span class="identifier">find_if</span><span class="special">(</span><span class="identifier">Sequence</span><span class="special">&</span> <span class="identifier">seq</span><span class="special">);</span> |
| </pre> |
| <div class="table"> |
| <a name="id1008623"></a><p class="title"><b>Table 1.53. Parameters</b></p> |
| <div class="table-contents"><table class="table" summary="Parameters"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Parameter |
| </p> |
| </th> |
| <th> |
| <p> |
| Requirement |
| </p> |
| </th> |
| <th> |
| <p> |
| Description |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">seq</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| A model of <a class="link" href="../../../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward |
| Sequence</a> |
| </p> |
| </td> |
| <td> |
| <p> |
| The sequence to search |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">F</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| A unary <a href="http://www.boost.org/libs/mpl/doc/refmanual/lambda-expression.html" target="_top">MPL |
| Lambda Expression</a> |
| </p> |
| </td> |
| <td> |
| <p> |
| The search predicate |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <br class="table-break"><a name="fusion.algorithm.query.functions.find_if.expression_semantics"></a><h6> |
| <a name="id1008749"></a> |
| <a class="link" href="find_if.html#fusion.algorithm.query.functions.find_if.expression_semantics">Expression |
| Semantics</a> |
| </h6> |
| <pre class="programlisting"><a class="link" href="find_if.html" title="find_if"><code class="computeroutput"><span class="identifier">find_if</span></code></a><span class="special"><</span><span class="identifier">F</span><span class="special">>(</span><span class="identifier">seq</span><span class="special">)</span> |
| </pre> |
| <p> |
| <span class="bold"><strong>Return type</strong></span>: An iterator of the same |
| iterator category as the iterators of <code class="computeroutput"><span class="identifier">seq</span></code>. |
| </p> |
| <p> |
| <span class="bold"><strong>Semantics</strong></span>: Returns the first element |
| of <code class="computeroutput"><span class="identifier">seq</span></code> for which <a href="http://www.boost.org/libs/mpl/doc/refmanual/lambda-expression.html" target="_top">MPL |
| Lambda Expression</a> <code class="computeroutput"><span class="identifier">F</span></code> |
| evaluates to <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span></code>, or <code class="computeroutput"><a class="link" href="../../../sequence/intrinsic/functions/end.html" title="end"><code class="computeroutput"><span class="identifier">end</span></code></a><span class="special">(</span><span class="identifier">seq</span><span class="special">)</span></code> |
| if there is no such element. |
| </p> |
| <a name="fusion.algorithm.query.functions.find_if.complexity"></a><h6> |
| <a name="id1008884"></a> |
| <a class="link" href="find_if.html#fusion.algorithm.query.functions.find_if.complexity">Complexity</a> |
| </h6> |
| <p> |
| Linear. At most <code class="computeroutput"><a class="link" href="../../../sequence/intrinsic/metafunctions/size.html" title="size"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">size</span></code></a><span class="special"><</span><span class="identifier">Sequence</span><span class="special">>::</span><span class="identifier">value</span></code> comparisons. |
| </p> |
| <div class="orderedlist"><ol class="orderedlist" type="1"> |
| <li class="listitem"> |
| include <boost/fusion/algorithm/query/find_if.hpp> |
| </li> |
| <li class="listitem"> |
| include <boost/fusion/include/find_if.hpp> |
| </li> |
| </ol></div> |
| <a name="fusion.algorithm.query.functions.find_if.example"></a><h6> |
| <a name="id1008955"></a> |
| <a class="link" href="find_if.html#fusion.algorithm.query.functions.find_if.example">Example</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">const</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="keyword">double</span><span class="special">,</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">vec</span><span class="special">(</span><span class="number">1.0</span><span class="special">,</span><span class="number">2</span><span class="special">);</span> |
| <span class="identifier">assert</span><span class="special">(*</span><a class="link" href="find_if.html" title="find_if"><code class="computeroutput"><span class="identifier">find_if</span></code></a><span class="special"><</span><span class="identifier">is_integral</span><span class="special"><</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">_</span><span class="special">></span> <span class="special">>(</span><span class="identifier">vec</span><span class="special">)</span> <span class="special">==</span> <span class="number">2</span><span class="special">);</span> |
| <span class="identifier">assert</span><span class="special">(</span><a class="link" href="find_if.html" title="find_if"><code class="computeroutput"><span class="identifier">find_if</span></code></a><span class="special"><</span><span class="identifier">is_class</span><span class="special"><</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">_</span><span class="special">></span> <span class="special">>(</span><span class="identifier">vec</span><span class="special">)</span> <span class="special">==</span> <a class="link" href="../../../sequence/intrinsic/functions/end.html" title="end"><code class="computeroutput"><span class="identifier">end</span></code></a><span class="special">(</span><span class="identifier">vec</span><span class="special">));</span> |
| </pre> |
| </div> |
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| <td align="right"><div class="copyright-footer">Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias |
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| 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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