1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>filter_view</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="../view.html" title="View"> 9<link rel="prev" href="single_view.html" title="single_view"> 10<link rel="next" href="iterator_range.html" title="iterator_range"> 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="single_view.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../view.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="iterator_range.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="fusion.view.filter_view"></a><a class="link" href="filter_view.html" title="filter_view">filter_view</a> 28</h3></div></div></div> 29<h5> 30<a name="fusion.view.filter_view.h0"></a> 31 <span class="phrase"><a name="fusion.view.filter_view.description"></a></span><a class="link" href="filter_view.html#fusion.view.filter_view.description">Description</a> 32 </h5> 33<p> 34 <code class="computeroutput"><span class="identifier">filter_view</span></code> is a view into 35 a subset of its underlying sequence's elements satisfying a given predicate 36 (an <a href="http://www.boost.org/libs/mpl" target="_top">MPL</a> metafunction). 37 The <code class="computeroutput"><span class="identifier">filter_view</span></code> presents 38 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>. 39 </p> 40<h5> 41<a name="fusion.view.filter_view.h1"></a> 42 <span class="phrase"><a name="fusion.view.filter_view.header"></a></span><a class="link" href="filter_view.html#fusion.view.filter_view.header">Header</a> 43 </h5> 44<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> 45<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> 46</pre> 47<h5> 48<a name="fusion.view.filter_view.h2"></a> 49 <span class="phrase"><a name="fusion.view.filter_view.synopsis"></a></span><a class="link" href="filter_view.html#fusion.view.filter_view.synopsis">Synopsis</a> 50 </h5> 51<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> 52<span class="keyword">struct</span> <span class="identifier">filter_view</span><span class="special">;</span> 53</pre> 54<h5> 55<a name="fusion.view.filter_view.h3"></a> 56 <span class="phrase"><a name="fusion.view.filter_view.template_parameters"></a></span><a class="link" href="filter_view.html#fusion.view.filter_view.template_parameters">Template 57 parameters</a> 58 </h5> 59<div class="informaltable"><table class="table"> 60<colgroup> 61<col> 62<col> 63<col> 64</colgroup> 65<thead><tr> 66<th> 67 <p> 68 Parameter 69 </p> 70 </th> 71<th> 72 <p> 73 Description 74 </p> 75 </th> 76<th> 77 <p> 78 Default 79 </p> 80 </th> 81</tr></thead> 82<tbody> 83<tr> 84<td> 85 <p> 86 <code class="computeroutput"><span class="identifier">Sequence</span></code> 87 </p> 88 </td> 89<td> 90 <p> 91 A <a class="link" href="../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward 92 Sequence</a> 93 </p> 94 </td> 95<td> 96 </td> 97</tr> 98<tr> 99<td> 100 <p> 101 <code class="computeroutput"><span class="identifier">Pred</span></code> 102 </p> 103 </td> 104<td> 105 <p> 106 A unary <a href="http://www.boost.org/libs/mpl/doc/refmanual/lambda-expression.html" target="_top">MPL 107 Lambda Expression</a> 108 </p> 109 </td> 110<td> 111 </td> 112</tr> 113</tbody> 114</table></div> 115<h5> 116<a name="fusion.view.filter_view.h4"></a> 117 <span class="phrase"><a name="fusion.view.filter_view.model_of"></a></span><a class="link" href="filter_view.html#fusion.view.filter_view.model_of">Model 118 of</a> 119 </h5> 120<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 121<li class="listitem"> 122 <a class="link" href="../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward Sequence</a> 123 </li> 124<li class="listitem"> 125 <a class="link" href="../sequence/concepts/associative_sequence.html" title="Associative Sequence">Associative 126 Sequence</a> if <code class="computeroutput"><span class="identifier">Sequence</span></code> 127 implements the <a class="link" href="../sequence/concepts/associative_sequence.html" title="Associative Sequence">Associative 128 Sequence</a> model. 129 </li> 130</ul></div> 131<div class="variablelist"> 132<p class="title"><b>Notation</b></p> 133<dl class="variablelist"> 134<dt><span class="term"><code class="computeroutput"><span class="identifier">F</span></code></span></dt> 135<dd><p> 136 A <code class="computeroutput"><span class="identifier">filter_view</span></code> type 137 </p></dd> 138<dt><span class="term"><code class="computeroutput"><span class="identifier">f</span></code>, <code class="computeroutput"><span class="identifier">f2</span></code></span></dt> 139<dd><p> 140 Instances of <code class="computeroutput"><span class="identifier">filter_view</span></code> 141 </p></dd> 142<dt><span class="term"><code class="computeroutput"><span class="identifier">s</span></code></span></dt> 143<dd><p> 144 A <a class="link" href="../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward 145 Sequence</a> 146 </p></dd> 147</dl> 148</div> 149<h5> 150<a name="fusion.view.filter_view.h5"></a> 151 <span class="phrase"><a name="fusion.view.filter_view.expression_semantics"></a></span><a class="link" href="filter_view.html#fusion.view.filter_view.expression_semantics">Expression 152 Semantics</a> 153 </h5> 154<p> 155 Semantics of an expression is defined only where it differs from, or is not 156 defined in the implemented models. 157 </p> 158<div class="informaltable"><table class="table"> 159<colgroup> 160<col> 161<col> 162</colgroup> 163<thead><tr> 164<th> 165 <p> 166 Expression 167 </p> 168 </th> 169<th> 170 <p> 171 Semantics 172 </p> 173 </th> 174</tr></thead> 175<tbody> 176<tr> 177<td> 178 <p> 179 <code class="computeroutput"><span class="identifier">F</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span></code> 180 </p> 181 </td> 182<td> 183 <p> 184 Creates a <code class="computeroutput"><span class="identifier">filter_view</span></code> 185 given a sequence, <code class="computeroutput"><span class="identifier">s</span></code>. 186 </p> 187 </td> 188</tr> 189<tr> 190<td> 191 <p> 192 <code class="computeroutput"><span class="identifier">F</span><span class="special">(</span><span class="identifier">f</span><span class="special">)</span></code> 193 </p> 194 </td> 195<td> 196 <p> 197 Copy constructs a <code class="computeroutput"><span class="identifier">filter_view</span></code> 198 from another <code class="computeroutput"><span class="identifier">filter_view</span></code>, 199 <code class="computeroutput"><span class="identifier">f</span></code>. 200 </p> 201 </td> 202</tr> 203<tr> 204<td> 205 <p> 206 <code class="computeroutput"><span class="identifier">f</span> <span class="special">=</span> 207 <span class="identifier">f2</span></code> 208 </p> 209 </td> 210<td> 211 <p> 212 Assigns to a <code class="computeroutput"><span class="identifier">filter_view</span></code>, 213 <code class="computeroutput"><span class="identifier">f</span></code>, from another 214 <code class="computeroutput"><span class="identifier">filter_view</span></code>, <code class="computeroutput"><span class="identifier">f2</span></code>. 215 </p> 216 </td> 217</tr> 218</tbody> 219</table></div> 220<h5> 221<a name="fusion.view.filter_view.h6"></a> 222 <span class="phrase"><a name="fusion.view.filter_view.example"></a></span><a class="link" href="filter_view.html#fusion.view.filter_view.example">Example</a> 223 </h5> 224<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> 225<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> 226<span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_class</span><span class="special">;</span> 227 228<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> 229 230<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> 231<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> 232<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> 233</pre> 234</div> 235<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 236<td align="left"></td> 237<td align="right"><div class="copyright-footer">Copyright © 2001-2006, 2011, 2012 Joel de Guzman, 238 Dan Marsden, Tobias Schwinger<p> 239 Distributed under the Boost Software License, Version 1.0. (See accompanying 240 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>) 241 </p> 242</div></td> 243</tr></table> 244<hr> 245<div class="spirit-nav"> 246<a accesskey="p" href="single_view.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../view.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="iterator_range.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 247</div> 248</body> 249</html> 250
