1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>equal_to</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="prior.html" title="prior"> 10<link rel="next" href="distance.html" title="distance"> 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="prior.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="distance.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="fusion.iterator.metafunctions.equal_to"></a><a class="link" href="equal_to.html" title="equal_to">equal_to</a> 28</h4></div></div></div> 29<h6> 30<a name="fusion.iterator.metafunctions.equal_to.h0"></a> 31 <span class="phrase"><a name="fusion.iterator.metafunctions.equal_to.description"></a></span><a class="link" href="equal_to.html#fusion.iterator.metafunctions.equal_to.description">Description</a> 32 </h6> 33<p> 34 Returns a true-valued <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL 35 Integral Constant</a> if <code class="computeroutput"><span class="identifier">I</span></code> 36 and <code class="computeroutput"><span class="identifier">J</span></code> are equal. 37 </p> 38<h6> 39<a name="fusion.iterator.metafunctions.equal_to.h1"></a> 40 <span class="phrase"><a name="fusion.iterator.metafunctions.equal_to.synopsis"></a></span><a class="link" href="equal_to.html#fusion.iterator.metafunctions.equal_to.synopsis">Synopsis</a> 41 </h6> 42<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> 43 <span class="keyword">typename</span> <span class="identifier">I</span><span class="special">,</span> 44 <span class="keyword">typename</span> <span class="identifier">J</span> 45 <span class="special">></span> 46<span class="keyword">struct</span> <span class="identifier">equal_to</span> 47<span class="special">{</span> 48 <span class="keyword">typedef</span> <span class="emphasis"><em>unspecified</em></span> <span class="identifier">type</span><span class="special">;</span> 49<span class="special">};</span> 50</pre> 51<div class="table"> 52<a name="fusion.iterator.metafunctions.equal_to.t0"></a><p class="title"><b>Table 1.15. Parameters</b></p> 53<div class="table-contents"><table class="table" summary="Parameters"> 54<colgroup> 55<col> 56<col> 57<col> 58</colgroup> 59<thead><tr> 60<th> 61 <p> 62 Parameter 63 </p> 64 </th> 65<th> 66 <p> 67 Requirement 68 </p> 69 </th> 70<th> 71 <p> 72 Description 73 </p> 74 </th> 75</tr></thead> 76<tbody><tr> 77<td> 78 <p> 79 <code class="computeroutput"><span class="identifier">I</span></code>, <code class="computeroutput"><span class="identifier">J</span></code> 80 </p> 81 </td> 82<td> 83 <p> 84 Any fusion iterators 85 </p> 86 </td> 87<td> 88 <p> 89 Operation's arguments 90 </p> 91 </td> 92</tr></tbody> 93</table></div> 94</div> 95<br class="table-break"><h6> 96<a name="fusion.iterator.metafunctions.equal_to.h2"></a> 97 <span class="phrase"><a name="fusion.iterator.metafunctions.equal_to.expression_semantics"></a></span><a class="link" href="equal_to.html#fusion.iterator.metafunctions.equal_to.expression_semantics">Expression 98 Semantics</a> 99 </h6> 100<pre class="programlisting"><a class="link" href="equal_to.html" title="equal_to"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">equal_to</span></code></a><span class="special"><</span><span class="identifier">I</span><span class="special">,</span> <span class="identifier">J</span><span class="special">>::</span><span class="identifier">type</span> 101</pre> 102<p> 103 <span class="bold"><strong>Return type</strong></span>: A model of <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL 104 Integral Constant</a>. 105 </p> 106<p> 107 <span class="bold"><strong>Semantics</strong></span>: Returns <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> 108 if <code class="computeroutput"><span class="identifier">I</span></code> and <code class="computeroutput"><span class="identifier">J</span></code> are iterators to the same position. 109 Returns <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">false_</span></code> otherwise. 110 </p> 111<h6> 112<a name="fusion.iterator.metafunctions.equal_to.h3"></a> 113 <span class="phrase"><a name="fusion.iterator.metafunctions.equal_to.header"></a></span><a class="link" href="equal_to.html#fusion.iterator.metafunctions.equal_to.header">Header</a> 114 </h6> 115<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">iterator</span><span class="special">/</span><span class="identifier">equal_to</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 116<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">equal_to</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 117</pre> 118<h6> 119<a name="fusion.iterator.metafunctions.equal_to.h4"></a> 120 <span class="phrase"><a name="fusion.iterator.metafunctions.equal_to.example"></a></span><a class="link" href="equal_to.html#fusion.iterator.metafunctions.equal_to.example">Example</a> 121 </h6> 122<pre class="programlisting"><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="keyword">int</span><span class="special">,</span><span class="keyword">double</span><span class="special">></span> <span class="identifier">vec</span><span class="special">;</span> 123<span class="keyword">typedef</span> <a class="link" href="../../sequence/intrinsic/metafunctions/begin.html" title="begin"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">begin</span></code></a><span class="special"><</span><span class="identifier">vec</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">first</span><span class="special">;</span> 124<span class="keyword">typedef</span> <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">vec</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">last</span><span class="special">;</span> 125<span class="identifier">BOOST_MPL_ASSERT</span><span class="special">((</span><a class="link" href="equal_to.html" title="equal_to"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">equal_to</span></code></a><span class="special"><</span><span class="identifier">first</span><span class="special">,</span> <span class="identifier">first</span><span class="special">>));</span> 126<span class="identifier">BOOST_MPL_ASSERT_NOT</span><span class="special">((</span><a class="link" href="equal_to.html" title="equal_to"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">equal_to</span></code></a><span class="special"><</span><span class="identifier">first</span><span class="special">,</span><span class="identifier">last</span><span class="special">>));</span> 127</pre> 128</div> 129<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 130<td align="left"></td> 131<td align="right"><div class="copyright-footer">Copyright © 2001-2006, 2011, 2012 Joel de Guzman, 132 Dan Marsden, Tobias Schwinger<p> 133 Distributed under the Boost Software License, Version 1.0. (See accompanying 134 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>) 135 </p> 136</div></td> 137</tr></table> 138<hr> 139<div class="spirit-nav"> 140<a accesskey="p" href="prior.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="distance.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 141</div> 142</body> 143</html> 144
