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 basic_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.expr_hpp" title="Header <boost/proto/expr.hpp>"> 10<link rel="prev" href="eval.html" title="Function eval"> 11<link rel="next" href="expr.html" title="Struct template expr"> 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 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class="refentrytitle">Struct template basic_expr</span></h2> 30<p>boost::proto::basic_expr — Simplified representation of a node in an expression tree.</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.expr_hpp" title="Header <boost/proto/expr.hpp>">boost/proto/expr.hpp</a>> 34 35</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Tag<span class="special">,</span> <span class="keyword">typename</span> Args<span class="special">,</span> <span class="keyword">long</span> Arity <span class="special">=</span> <span class="identifier">Args</span><span class="special">::</span><span class="identifier">arity</span><span class="special">></span> 36<span class="keyword">struct</span> <a class="link" href="basic_expr.html" title="Struct template basic_expr">basic_expr</a> <span class="special">{</span> 37 <span class="comment">// types</span> 38 <span class="keyword">typedef</span> <span class="identifier">Tag</span> <a name="boost.proto.basic_expr.proto_tag"></a><span class="identifier">proto_tag</span><span class="special">;</span> 39 <span class="keyword">typedef</span> <span class="identifier">Args</span> <a name="boost.proto.basic_expr.proto_args"></a><span class="identifier">proto_args</span><span class="special">;</span> 40 <span class="keyword">typedef</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">long_</span><span class="special"><</span> <span class="identifier">Arity</span> <span class="special">></span> <a name="boost.proto.basic_expr.proto_arity"></a><span class="identifier">proto_arity</span><span class="special">;</span> 41 <span class="keyword">typedef</span> <a class="link" href="basic_default_domain.html" title="Struct basic_default_domain">proto::basic_default_domain</a> <a name="boost.proto.basic_expr.proto_domain"></a><span class="identifier">proto_domain</span><span class="special">;</span> 42 <span class="keyword">typedef</span> <span class="identifier">basic_expr</span> <a name="boost.proto.basic_expr.proto_grammar"></a><span class="identifier">proto_grammar</span><span class="special">;</span> 43 <span class="keyword">typedef</span> <span class="identifier">basic_expr</span> <a name="boost.proto.basic_expr.proto_base_expr"></a><span class="identifier">proto_base_expr</span><span class="special">;</span> 44 <span class="keyword">typedef</span> <span class="identifier">basic_expr</span> <a name="boost.proto.basic_expr.proto_derived_expr"></a><span class="identifier">proto_derived_expr</span><span class="special">;</span> 45 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Args</span><span class="special">::</span><span class="identifier">child</span><em class="replaceable"><code><span class="identifier">N</span></code></em> <a name="boost.proto.basic_expr.proto_childN"></a><span class="identifier">proto_childN</span><span class="special">;</span> <span class="comment">// For each <em class="replaceable"><code>N</code></em> in <em class="replaceable"><code>[0,max(Arity,1))</code></em>.</span> 46 47 <span class="comment">// <a class="link" href="basic_expr.html#id-1_3_33_5_9_1_1_1_12-bb">public static functions</a></span> 48 <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span><span class="special">...</span> A<span class="special">></span> <span class="keyword">static</span> <span class="identifier">basic_expr</span> <span class="keyword">const</span> <a class="link" href="basic_expr.html#id-1_3_33_5_9_1_1_1_12_1-bb"><span class="identifier">make</span></a><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">...</span><span class="special">)</span><span class="special">;</span> 49 50 <span class="comment">// <a class="link" href="basic_expr.html#id-1_3_33_5_9_1_1_1_13-bb">public member functions</a></span> 51 <span class="identifier">basic_expr</span> <span class="special">&</span> <a class="link" href="basic_expr.html#id-1_3_33_5_9_1_1_1_13_1-bb"><span class="identifier">proto_base</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span> 52 <span class="identifier">basic_expr</span> <span class="keyword">const</span> <span class="special">&</span> <a class="link" href="basic_expr.html#id-1_3_33_5_9_1_1_1_13_2-bb"><span class="identifier">proto_base</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 53<span class="special">}</span><span class="special">;</span></pre></div> 54<div class="refsect1"> 55<a name="id-1.3.33.5.11.3.4"></a><h2>Description</h2> 56<p> 57 <code class="computeroutput">proto::basic_expr<></code> is a node in an expression 58 template tree. It is a container for its child sub-trees. It also serves as the 59 terminal nodes of the tree. 60 </p> 61<p> 62 <code class="computeroutput">Tag</code> is type that represents the operation 63 encoded by this expression. It is typically one of the structs in the 64 <code class="computeroutput">boost::proto::tag</code> namespace, but it doesn't 65 have to be. If <code class="computeroutput">Arity</code> is 0 then this 66 <code class="computeroutput">expr<></code> type represents a leaf in the 67 expression tree. 68 </p> 69<p> 70 <code class="computeroutput">Args</code> is a list of types representing 71 the children of this expression. It is an instantiation of one of 72 <code class="computeroutput"><a class="link" href="listN.html" title="Struct template listN">proto::list1<></a></code>, 73 <code class="computeroutput"><a class="link" href="listN.html" title="Struct template listN">proto::list2<></a></code>, 74 etc. The child types 75 must all themselves be either <code class="computeroutput">proto::expr<></code> 76 or <code class="computeroutput">proto::basic_expr<>&</code> (or extensions thereof via 77 <code class="computeroutput"><a class="link" href="extends.html" title="Struct template extends">proto::extends<></a></code> or 78 <code class="computeroutput"><a class="link" href="../../BOOST_PROTO_EXTENDS.html" title="Macro BOOST_PROTO_EXTENDS">BOOST_PROTO_EXTENDS</a>()</code>), unless 79 <code class="computeroutput">Arity</code> is 0, in which case 80 <code class="computeroutput">Args</code> must be 81 <code class="computeroutput">proto::term<T></code>, where 82 <code class="computeroutput">T</code> can be any type. 83 </p> 84<p> 85 <code class="computeroutput">proto::basic_expr<></code> is a valid Fusion 86 random-access sequence, where the elements of the sequence are the child 87 expressions. 88 </p> 89<div class="refsect2"> 90<a name="id-1.3.33.5.11.3.4.6"></a><h3> 91<a name="id-1_3_33_5_9_1_1_1_12-bb"></a><code class="computeroutput">basic_expr</code> public static functions</h3> 92<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> 93<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span><span class="special">...</span> A<span class="special">></span> <span class="keyword">static</span> <span class="identifier">basic_expr</span> <span class="keyword">const</span> <a name="id-1_3_33_5_9_1_1_1_12_1-bb"></a><span class="identifier">make</span><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">...</span> a<span class="special">)</span><span class="special">;</span></pre> 94<div class="variablelist"><table border="0" class="variablelist compact"> 95<colgroup> 96<col align="left" valign="top"> 97<col> 98</colgroup> 99<tbody> 100<tr> 101<td><p><span class="term">Requires:</span></p></td> 102<td><p> 103 The number of supplied arguments must be <code class="computeroutput">max(Arity,1)</code>. 104 </p></td> 105</tr> 106<tr> 107<td><p><span class="term">Returns:</span></p></td> 108<td><p> 109 A new <code class="computeroutput">basic_expr</code> object initialized with the specified arguments. 110 </p></td> 111</tr> 112</tbody> 113</table></div> 114</li></ol></div> 115</div> 116<div class="refsect2"> 117<a name="id-1.3.33.5.11.3.4.7"></a><h3> 118<a name="id-1_3_33_5_9_1_1_1_13-bb"></a><code class="computeroutput">basic_expr</code> public member functions</h3> 119<div class="orderedlist"><ol class="orderedlist" type="1"> 120<li class="listitem"> 121<pre class="literallayout"><span class="identifier">basic_expr</span> <span class="special">&</span> <a name="id-1_3_33_5_9_1_1_1_13_1-bb"></a><span class="identifier">proto_base</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre> 122<div class="variablelist"><table border="0" class="variablelist compact"> 123<colgroup> 124<col align="left" valign="top"> 125<col> 126</colgroup> 127<tbody><tr> 128<td><p><span class="term">Returns:</span></p></td> 129<td><p> 130 <code class="computeroutput">*this</code> 131 </p></td> 132</tr></tbody> 133</table></div> 134</li> 135<li class="listitem"> 136<pre class="literallayout"><span class="identifier">basic_expr</span> <span class="keyword">const</span> <span class="special">&</span> <a name="id-1_3_33_5_9_1_1_1_13_2-bb"></a><span class="identifier">proto_base</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre> 137<p> 138 This is an overloaded member function, provided for convenience. It differs from 139 the above function only in what argument(s) it accepts. 140 </p> 141</li> 142</ol></div> 143</div> 144</div> 145</div> 146<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 147<td align="left"></td> 148<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> 149 Distributed under the Boost Software License, Version 1.0. (See accompanying 150 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>) 151 </p> 152</div></td> 153</tr></table> 154<hr> 155<div class="spirit-nav"> 156<a accesskey="p" href="eval.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../proto/reference.html#header.boost.proto.expr_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.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 157</div> 158</body> 159</html> 160
