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 _expr</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.transform.arg_hpp" title="Header <boost/proto/transform/arg.hpp>"> 10<link rel="prev" href="right.html" title="Function right"> 11<link rel="next" href="_expr/impl.html" title="Struct template impl"> 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="right.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../proto/reference.html#header.boost.proto.transform.arg_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="_expr/impl.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 25</div> 26<div class="refentry"> 27<a name="boost.proto._expr"></a><div class="titlepage"></div> 28<div class="refnamediv"> 29<h2><span class="refentrytitle">Struct _expr</span></h2> 30<p>boost::proto::_expr — A <a class="link" href="../../PrimitiveTransform.html" title="Concept PrimitiveTransform">PrimitiveTransform</a> that returns the current expression unmodified. </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.transform.arg_hpp" title="Header <boost/proto/transform/arg.hpp>">boost/proto/transform/arg.hpp</a>> 34 35</span> 36<span class="keyword">struct</span> <a class="link" href="_expr.html" title="Struct _expr">_expr</a> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="transform.html" title="Struct template transform">proto::transform</a><span class="special"><</span> <span class="identifier">_expr</span> <span class="special">></span> <span class="special">{</span> 37 <span class="comment">// member classes/structs/unions</span> 38 <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> State<span class="special">,</span> <span class="keyword">typename</span> Data<span class="special">></span> 39 <span class="keyword">struct</span> <a class="link" href="_expr/impl.html" title="Struct template impl">impl</a> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="transform_impl.html" title="Struct template transform_impl">proto::transform_impl</a><span class="special"><</span> <span class="identifier">Expr</span><span class="special">,</span> <span class="identifier">State</span><span class="special">,</span> <span class="identifier">Data</span> <span class="special">></span> <span class="special">{</span> 40 <span class="comment">// types</span> 41 <span class="keyword">typedef</span> <span class="identifier">Expr</span> <a class="link" href="_expr/impl.html#boost.proto._expr.impl.result_type"><span class="identifier">result_type</span></a><span class="special">;</span> 42 43 <span class="comment">// <a class="link" href="_expr/impl.html#id-1_3_33_5_41_2_1_1_4_4-bb">public member functions</a></span> 44 <span class="identifier">Expr</span> <a class="link" href="_expr/impl.html#id-1_3_33_5_41_2_1_1_4_4_1-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">expr_param</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">state_param</span><span class="special">,</span> 45 <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">data_param</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 46 <span class="special">}</span><span class="special">;</span> 47<span class="special">}</span><span class="special">;</span></pre></div> 48<div class="refsect1"> 49<a name="id-1.3.33.5.43.4.4"></a><h2>Description</h2> 50<p> 51 Example: 52 </p> 53<pre class="programlisting"><a class="link" href="terminal.html" title="Struct template terminal">proto::terminal</a><span class="special"><</span><span class="keyword">int</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span> <span class="identifier">i</span> <span class="special">=</span> <span class="special">{</span><span class="number">42</span><span class="special">}</span><span class="special">;</span> 54<a class="link" href="terminal.html" title="Struct template terminal">proto::terminal</a><span class="special"><</span><span class="keyword">int</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span> <span class="special">&</span> <span class="identifier">j</span> <span class="special">=</span> <span class="identifier">proto</span><span class="special">::</span><span class="identifier">_expr</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">i</span><span class="special">)</span><span class="special">;</span> 55<span class="identifier">assert</span><span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">addressof</span><span class="special">(</span><span class="identifier">i</span><span class="special">)</span> <span class="special">==</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">addressof</span><span class="special">(</span><span class="identifier">j</span><span class="special">)</span> <span class="special">)</span><span class="special">;</span></pre> 56<p> 57 </p> 58</div> 59</div> 60<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 61<td align="left"></td> 62<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> 63 Distributed under the Boost Software License, Version 1.0. (See accompanying 64 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>) 65 </p> 66</div></td> 67</tr></table> 68<hr> 69<div class="spirit-nav"> 70<a accesskey="p" href="right.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../proto/reference.html#header.boost.proto.transform.arg_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="_expr/impl.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 71</div> 72</body> 73</html> 74
