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 null_eval</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.context.null_hpp" title="Header <boost/proto/context/null.hpp>"> 10<link rel="prev" href="default_context/eval.html" title="Struct template eval"> 11<link rel="next" href="null_context.html" title="Struct null_context"> 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" 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class="refentry"> 27<a name="boost.proto.context.null_eval"></a><div class="titlepage"></div> 28<div class="refnamediv"> 29<h2><span class="refentrytitle">Struct template null_eval</span></h2> 30<p>boost::proto::context::null_eval</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.context.null_hpp" title="Header <boost/proto/context/null.hpp>">boost/proto/context/null.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> <span class="keyword">typename</span> Context<span class="special">></span> 36<span class="keyword">struct</span> <a class="link" href="null_eval.html" title="Struct template null_eval">null_eval</a> <span class="special">{</span> 37 <span class="comment">// types</span> 38 <span class="keyword">typedef</span> <span class="keyword">void</span> <a name="boost.proto.context.null_eval.result_type"></a><span class="identifier">result_type</span><span class="special">;</span> 39 40 <span class="comment">// <a class="link" href="null_eval.html#id-1_3_33_5_56_2_1_1_1_3-bb">public member functions</a></span> 41 <span class="keyword">void</span> <a class="link" href="null_eval.html#id-1_3_33_5_56_2_1_1_1_3_1-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">Expr</span> <span class="special">&</span><span class="special">,</span> <span class="identifier">Context</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 42<span class="special">}</span><span class="special">;</span></pre></div> 43<div class="refsect1"> 44<a name="id-1.3.33.5.58.4.4"></a><h2>Description</h2> 45<div class="refsect2"> 46<a name="id-1.3.33.5.58.4.4.2"></a><h3> 47<a name="id-1_3_33_5_56_2_1_1_1_3-bb"></a><code class="computeroutput">null_eval</code> public member functions</h3> 48<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> 49<pre class="literallayout"><span class="keyword">void</span> <a name="id-1_3_33_5_56_2_1_1_1_3_1-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">Expr</span> <span class="special">&</span> expr<span class="special">,</span> <span class="identifier">Context</span> <span class="special">&</span> context<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre> 50<p> 51 For <code class="computeroutput">N</code> in <code class="computeroutput">[0,Expr arity)</code>, 52 evaluate: 53 </p> 54<pre class="programlisting"><code class="computeroutput"><a class="link" href="../eval.html" title="Function eval">proto::eval</a></code>(<code class="computeroutput"><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a></code><N>(expr), context)</pre> 55<p> 56 </p> 57</li></ol></div> 58</div> 59</div> 60</div> 61<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 62<td align="left"></td> 63<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> 64 Distributed under the Boost Software License, Version 1.0. (See accompanying 65 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>) 66 </p> 67</div></td> 68</tr></table> 69<hr> 70<div class="spirit-nav"> 71<a accesskey="p" href="default_context/eval.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../../proto/reference.html#header.boost.proto.context.null_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="null_context.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 72</div> 73</body> 74</html> 75
