<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Struct template value</title> <link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../../../proto/reference.html#header.boost.proto.traits_hpp" title="Header <boost/proto/traits.hpp>"> <link rel="prev" href="child.html" title="Struct template child"> <link rel="next" href="left.html" title="Struct template left"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> <td align="center"><a href="../../../../../index.html">Home</a></td> <td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <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> </div> <div class="refentry"> <a name="boost.proto.result_of.value"></a><div class="titlepage"></div> <div class="refnamediv"> <h2><span class="refentrytitle">Struct template value</span></h2> <p>boost::proto::result_of::value — A metafunction that returns the type of the value of a terminal Proto expression. </p> </div> <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> <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>> </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> <span class="keyword">struct</span> <a class="link" href="value.html" title="Struct template value">value</a> <span class="special">{</span> <span class="comment">// <a class="link" href="value.html#boost.proto.result_of.valuetypes">types</a></span> <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> <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> <span class="special">}</span><span class="special">;</span></pre></div> <div class="refsect1"> <a name="idm45555179631904"></a><h2>Description</h2> <div class="refsect2"> <a name="idm45555179631488"></a><h3> <a name="boost.proto.result_of.valuetypes"></a><code class="computeroutput">value</code> public types</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <p> <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> <p> The raw type of the value as it is stored within <code class="computeroutput">Expr</code>. This may be a value or a reference. </p> </li> <li class="listitem"> <p> <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> <p> If <code class="computeroutput">Expr</code> is not a reference type, <code class="computeroutput">type</code> is computed as follows: </p> <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"><p> <code class="computeroutput">T const(&)[N]</code> becomes <code class="computeroutput">T[N]</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T[N]</code> becomes <code class="computeroutput">T[N]</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T(&)[N]</code> becomes <code class="computeroutput">T[N]</code> </p></li> <li class="listitem"><p> <code class="computeroutput">R(&)(A...)</code> becomes <code class="computeroutput">R(&)(A...)</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T const &</code> becomes <code class="computeroutput">T</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T &</code> becomes <code class="computeroutput">T</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T</code> becomes <code class="computeroutput">T</code> </p></li> </ul></div> <p> </p> <p> If <code class="computeroutput">Expr</code> is a non-const reference type, <code class="computeroutput">type</code> is computed as follows: </p> <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"><p> <code class="computeroutput">T const(&)[N]</code> becomes <code class="computeroutput">T const(&)[N]</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T[N]</code> becomes <code class="computeroutput">T(&)[N]</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T(&)[N]</code> becomes <code class="computeroutput">T(&)[N]</code> </p></li> <li class="listitem"><p> <code class="computeroutput">R(&)(A...)</code> becomes <code class="computeroutput">R(&)(A...)</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T const &</code> becomes <code class="computeroutput">T const &</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T &</code> becomes <code class="computeroutput">T &</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T</code> becomes <code class="computeroutput">T &</code> </p></li> </ul></div> <p> </p> <p> If <code class="computeroutput">Expr</code> is a const reference type, <code class="computeroutput">type</code> is computed as follows: </p> <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"><p> <code class="computeroutput">T const(&)[N]</code> becomes <code class="computeroutput">T const(&)[N]</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T[N]</code> becomes <code class="computeroutput">T const(&)[N]</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T(&)[N]</code> becomes <code class="computeroutput">T(&)[N]</code> </p></li> <li class="listitem"><p> <code class="computeroutput">R(&)(A...)</code> becomes <code class="computeroutput">R(&)(A...)</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T const &</code> becomes <code class="computeroutput">T const &</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T &</code> becomes <code class="computeroutput">T &</code> </p></li> <li class="listitem"><p> <code class="computeroutput">T</code> becomes <code class="computeroutput">T const &</code> </p></li> </ul></div> <p> </p> </li> </ol></div> </div> </div> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> 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>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <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> </div> </body> </html>