1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 5<title>Struct template value</title> 6<link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> 7<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 8<link rel="home" href="../../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> 9<link rel="up" href="../../../proto/reference.html#header.boost.proto.traits_hpp" title="Header <boost/proto/traits.hpp>"> 10<link rel="prev" href="child.html" title="Struct template child"> 11<link rel="next" href="left.html" title="Struct template left"> 12</head> 13<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 14<table cellpadding="2" width="100%"><tr> 15<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> 16<td align="center"><a href="../../../../../index.html">Home</a></td> 17<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> 18<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 19<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 20<td align="center"><a href="../../../../../more/index.htm">More</a></td> 21</tr></table> 22<hr> 23<div class="spirit-nav"> 24<a accesskey="p" href="child.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../../proto/reference.html#header.boost.proto.traits_hpp"><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="left.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 25</div> 26<div class="refentry"> 27<a name="boost.proto.result_of.value"></a><div class="titlepage"></div> 28<div class="refnamediv"> 29<h2><span class="refentrytitle">Struct template value</span></h2> 30<p>boost::proto::result_of::value — A metafunction that returns the type of the value of a terminal Proto expression. </p> 31</div> 32<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 33<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../../proto/reference.html#header.boost.proto.traits_hpp" title="Header <boost/proto/traits.hpp>">boost/proto/traits.hpp</a>> 34 35</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <a class="link" href="../../../Expr.html" title="Concept Expr">Expr</a><span class="special">></span> 36<span class="keyword">struct</span> <a class="link" href="value.html" title="Struct template value">value</a> <span class="special">{</span> 37 <span class="comment">// <a class="link" href="value.html#boost.proto.result_of.valuetypes">types</a></span> 38 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Expr</span><span class="special">::</span><span class="identifier">proto_child0</span> <a class="link" href="value.html#boost.proto.result_of.value.value_type"><span class="identifier">value_type</span></a><span class="special">;</span> 39 <span class="keyword">typedef</span> <em class="replaceable"><code><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></code></em> <a class="link" href="value.html#boost.proto.result_of.value.type"><span class="identifier">type</span></a><span class="special">;</span> 40<span class="special">}</span><span class="special">;</span></pre></div> 41<div class="refsect1"> 42<a name="id-1.3.33.5.41.14.4"></a><h2>Description</h2> 43<div class="refsect2"> 44<a name="id-1.3.33.5.41.14.4.2"></a><h3> 45<a name="boost.proto.result_of.valuetypes"></a><code class="computeroutput">value</code> 46 public 47 types</h3> 48<div class="orderedlist"><ol class="orderedlist" type="1"> 49<li class="listitem"> 50<p> 51<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Expr</span><span class="special">::</span><span class="identifier">proto_child0</span> <a name="boost.proto.result_of.value.value_type"></a><span class="identifier">value_type</span><span class="special">;</span></p> 52<p> 53 The raw type of the value as it is 54 stored within <code class="computeroutput">Expr</code>. This may be a value or a reference. 55 </p> 56</li> 57<li class="listitem"> 58<p> 59<span class="keyword">typedef</span> <em class="replaceable"><code><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></code></em> <a name="boost.proto.result_of.value.type"></a><span class="identifier">type</span><span class="special">;</span></p> 60<p> 61 If <code class="computeroutput">Expr</code> is not a reference type, <code class="computeroutput">type</code> 62 is computed as follows: 63 </p> 64<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 65<li class="listitem"><p> 66 <code class="computeroutput">T const(&)[N]</code> becomes <code class="computeroutput">T[N]</code> 67 </p></li> 68<li class="listitem"><p> 69 <code class="computeroutput">T[N]</code> becomes <code class="computeroutput">T[N]</code> 70 </p></li> 71<li class="listitem"><p> 72 <code class="computeroutput">T(&)[N]</code> becomes <code class="computeroutput">T[N]</code> 73 </p></li> 74<li class="listitem"><p> 75 <code class="computeroutput">R(&)(A...)</code> becomes <code class="computeroutput">R(&)(A...)</code> 76 </p></li> 77<li class="listitem"><p> 78 <code class="computeroutput">T const &</code> becomes <code class="computeroutput">T</code> 79 </p></li> 80<li class="listitem"><p> 81 <code class="computeroutput">T &</code> becomes <code class="computeroutput">T</code> 82 </p></li> 83<li class="listitem"><p> 84 <code class="computeroutput">T</code> becomes <code class="computeroutput">T</code> 85 </p></li> 86</ul></div> 87<p> 88 </p> 89<p> 90 If <code class="computeroutput">Expr</code> is a non-const reference type, <code class="computeroutput">type</code> 91 is computed as follows: 92 </p> 93<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 94<li class="listitem"><p> 95 <code class="computeroutput">T const(&)[N]</code> becomes <code class="computeroutput">T const(&)[N]</code> 96 </p></li> 97<li class="listitem"><p> 98 <code class="computeroutput">T[N]</code> becomes <code class="computeroutput">T(&)[N]</code> 99 </p></li> 100<li class="listitem"><p> 101 <code class="computeroutput">T(&)[N]</code> becomes <code class="computeroutput">T(&)[N]</code> 102 </p></li> 103<li class="listitem"><p> 104 <code class="computeroutput">R(&)(A...)</code> becomes <code class="computeroutput">R(&)(A...)</code> 105 </p></li> 106<li class="listitem"><p> 107 <code class="computeroutput">T const &</code> becomes <code class="computeroutput">T const &</code> 108 </p></li> 109<li class="listitem"><p> 110 <code class="computeroutput">T &</code> becomes <code class="computeroutput">T &</code> 111 </p></li> 112<li class="listitem"><p> 113 <code class="computeroutput">T</code> becomes <code class="computeroutput">T &</code> 114 </p></li> 115</ul></div> 116<p> 117 </p> 118<p> 119 If <code class="computeroutput">Expr</code> is a const reference type, <code class="computeroutput">type</code> 120 is computed as follows: 121 </p> 122<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 123<li class="listitem"><p> 124 <code class="computeroutput">T const(&)[N]</code> becomes <code class="computeroutput">T const(&)[N]</code> 125 </p></li> 126<li class="listitem"><p> 127 <code class="computeroutput">T[N]</code> becomes <code class="computeroutput">T const(&)[N]</code> 128 </p></li> 129<li class="listitem"><p> 130 <code class="computeroutput">T(&)[N]</code> becomes <code class="computeroutput">T(&)[N]</code> 131 </p></li> 132<li class="listitem"><p> 133 <code class="computeroutput">R(&)(A...)</code> becomes <code class="computeroutput">R(&)(A...)</code> 134 </p></li> 135<li class="listitem"><p> 136 <code class="computeroutput">T const &</code> becomes <code class="computeroutput">T const &</code> 137 </p></li> 138<li class="listitem"><p> 139 <code class="computeroutput">T &</code> becomes <code class="computeroutput">T &</code> 140 </p></li> 141<li class="listitem"><p> 142 <code class="computeroutput">T</code> becomes <code class="computeroutput">T const &</code> 143 </p></li> 144</ul></div> 145<p> 146 </p> 147</li> 148</ol></div> 149</div> 150</div> 151</div> 152<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 153<td align="left"></td> 154<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> 155 Distributed under the Boost Software License, Version 1.0. (See accompanying 156 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>) 157 </p> 158</div></td> 159</tr></table> 160<hr> 161<div class="spirit-nav"> 162<a accesskey="p" href="child.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../../proto/reference.html#header.boost.proto.traits_hpp"><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="left.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 163</div> 164</body> 165</html> 166
