1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>find_if</title> 5<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../../index.html" title="Chapter 1. Fusion 2.2"> 8<link rel="up" href="../metafunctions.html" title="Metafunctions"> 9<link rel="prev" href="find.html" title="find"> 10<link rel="next" href="count.html" title="count"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="find.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../metafunctions.html"><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="count.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h5 class="title"> 27<a name="fusion.algorithm.query.metafunctions.find_if"></a><a class="link" href="find_if.html" title="find_if">find_if</a> 28</h5></div></div></div> 29<h6> 30<a name="fusion.algorithm.query.metafunctions.find_if.h0"></a> 31 <span class="phrase"><a name="fusion.algorithm.query.metafunctions.find_if.description"></a></span><a class="link" href="find_if.html#fusion.algorithm.query.metafunctions.find_if.description">Description</a> 32 </h6> 33<p> 34 Returns the result type of <a class="link" href="../functions/find_if.html" title="find_if"><code class="computeroutput"><span class="identifier">find_if</span></code></a> given the sequence and 35 predicate types. 36 </p> 37<h6> 38<a name="fusion.algorithm.query.metafunctions.find_if.h1"></a> 39 <span class="phrase"><a name="fusion.algorithm.query.metafunctions.find_if.synopsis"></a></span><a class="link" href="find_if.html#fusion.algorithm.query.metafunctions.find_if.synopsis">Synopsis</a> 40 </h6> 41<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> 42 <span class="keyword">typename</span> <span class="identifier">Sequence</span><span class="special">,</span> 43 <span class="keyword">typename</span> <span class="identifier">Pred</span> 44 <span class="special">></span> 45<span class="keyword">struct</span> <span class="identifier">find_if</span> 46<span class="special">{</span> 47 <span class="keyword">typedef</span> <span class="emphasis"><em>unspecified</em></span> <span class="identifier">type</span><span class="special">;</span> 48<span class="special">};</span> 49</pre> 50<div class="table"> 51<a name="fusion.algorithm.query.metafunctions.find_if.t0"></a><p class="title"><b>Table 1.63. Parameters</b></p> 52<div class="table-contents"><table class="table" summary="Parameters"> 53<colgroup> 54<col> 55<col> 56<col> 57</colgroup> 58<thead><tr> 59<th> 60 <p> 61 Parameter 62 </p> 63 </th> 64<th> 65 <p> 66 Requirement 67 </p> 68 </th> 69<th> 70 <p> 71 Description 72 </p> 73 </th> 74</tr></thead> 75<tbody> 76<tr> 77<td> 78 <p> 79 <code class="computeroutput"><span class="identifier">Sequence</span></code> 80 </p> 81 </td> 82<td> 83 <p> 84 A model of <a class="link" href="../../../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward 85 Sequence</a> 86 </p> 87 </td> 88<td> 89 <p> 90 Operation's argument 91 </p> 92 </td> 93</tr> 94<tr> 95<td> 96 <p> 97 <code class="computeroutput"><span class="identifier">Pred</span></code> 98 </p> 99 </td> 100<td> 101 <p> 102 A model of <a href="http://www.boost.org/libs/mpl/doc/refmanual/lambda-expression.html" target="_top">MPL 103 Lambda Expression</a> 104 </p> 105 </td> 106<td> 107 <p> 108 Operation's arguments 109 </p> 110 </td> 111</tr> 112</tbody> 113</table></div> 114</div> 115<br class="table-break"><h6> 116<a name="fusion.algorithm.query.metafunctions.find_if.h2"></a> 117 <span class="phrase"><a name="fusion.algorithm.query.metafunctions.find_if.expression_semantics"></a></span><a class="link" href="find_if.html#fusion.algorithm.query.metafunctions.find_if.expression_semantics">Expression 118 Semantics</a> 119 </h6> 120<pre class="programlisting"><a class="link" href="find_if.html" title="find_if"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">find_if</span></code></a><span class="special"><</span><span class="identifier">Sequence</span><span class="special">,</span> <span class="identifier">Pred</span><span class="special">>::</span><span class="identifier">type</span> 121</pre> 122<p> 123 <span class="bold"><strong>Return type</strong></span>: A model of the same iterator 124 category as the iterators of <code class="computeroutput"><span class="identifier">Sequence</span></code>. 125 </p> 126<p> 127 <span class="bold"><strong>Semantics</strong></span>: Returns an iterator to the 128 first element in <code class="computeroutput"><span class="identifier">Sequence</span></code> 129 for which <code class="computeroutput"><span class="identifier">Pred</span></code> evaluates 130 to true. Returns <code class="computeroutput"><a class="link" href="../../../sequence/intrinsic/metafunctions/end.html" title="end"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">end</span></code></a><span class="special"><</span><span class="identifier">Sequence</span><span class="special">>::</span><span class="identifier">type</span></code> if there is no such element. 131 </p> 132<h6> 133<a name="fusion.algorithm.query.metafunctions.find_if.h3"></a> 134 <span class="phrase"><a name="fusion.algorithm.query.metafunctions.find_if.complexity"></a></span><a class="link" href="find_if.html#fusion.algorithm.query.metafunctions.find_if.complexity">Complexity</a> 135 </h6> 136<p> 137 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. 138 </p> 139<h6> 140<a name="fusion.algorithm.query.metafunctions.find_if.h4"></a> 141 <span class="phrase"><a name="fusion.algorithm.query.metafunctions.find_if.header"></a></span><a class="link" href="find_if.html#fusion.algorithm.query.metafunctions.find_if.header">Header</a> 142 </h6> 143<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">algorithm</span><span class="special">/</span><span class="identifier">query</span><span class="special">/</span><span class="identifier">find_if</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 144<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">find_if</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 145</pre> 146</div> 147<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 148<td align="left"></td> 149<td align="right"><div class="copyright-footer">Copyright © 2001-2006, 2011, 2012 Joel de Guzman, 150 Dan Marsden, Tobias Schwinger<p> 151 Distributed under the Boost Software License, Version 1.0. (See accompanying 152 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>) 153 </p> 154</div></td> 155</tr></table> 156<hr> 157<div class="spirit-nav"> 158<a accesskey="p" href="find.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../metafunctions.html"><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="count.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 159</div> 160</body> 161</html> 162
