1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Generator Directive Duplicating Attributes (duplicate[])</title> 5<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../../index.html" title="Spirit 2.5.8"> 8<link rel="up" href="../directive.html" title="Generator Directives"> 9<link rel="prev" href="omit.html" title="Generator Directives Consuming Attributes (omit[] and skip[])"> 10<link rel="next" href="columns.html" title="Generator Directive Separating Output Into Columns (columns[])"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="omit.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../directive.html"><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="columns.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h5 class="title"> 27<a name="spirit.karma.reference.directive.duplicate"></a><a class="link" href="duplicate.html" title="Generator Directive Duplicating Attributes (duplicate[])">Generator 28 Directive Duplicating Attributes (<code class="computeroutput"><span class="identifier">duplicate</span><span class="special">[]</span></code>)</a> 29</h5></div></div></div> 30<h6> 31<a name="spirit.karma.reference.directive.duplicate.h0"></a> 32 <span class="phrase"><a name="spirit.karma.reference.directive.duplicate.description"></a></span><a class="link" href="duplicate.html#spirit.karma.reference.directive.duplicate.description">Description</a> 33 </h6> 34<p> 35 The directive <code class="computeroutput"><span class="identifier">duplicate</span><span class="special">[]</span></code> duplicates its attribute to all elements 36 of the embedded generator if this is a sequence generator. Otherwise 37 it does nothing. 38 </p> 39<h6> 40<a name="spirit.karma.reference.directive.duplicate.h1"></a> 41 <span class="phrase"><a name="spirit.karma.reference.directive.duplicate.header"></a></span><a class="link" href="duplicate.html#spirit.karma.reference.directive.duplicate.header">Header</a> 42 </h6> 43<pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/karma/directive/duplicate.hpp></span> 44<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">karma_duplicate</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 45</pre> 46<p> 47 Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>. 48 </p> 49<div class="informaltable"><table class="table"> 50<colgroup><col></colgroup> 51<thead><tr><th> 52 <p> 53 Name 54 </p> 55 </th></tr></thead> 56<tbody><tr><td> 57 <p> 58 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">duplicate</span> <span class="comment">// 59 alias: boost::spirit::karma::duplicate</span></code> 60 </p> 61 </td></tr></tbody> 62</table></div> 63<h6> 64<a name="spirit.karma.reference.directive.duplicate.h2"></a> 65 <span class="phrase"><a name="spirit.karma.reference.directive.duplicate.model_of"></a></span><a class="link" href="duplicate.html#spirit.karma.reference.directive.duplicate.model_of">Model of</a> 66 </h6> 67<div class="blockquote"><blockquote class="blockquote"><p> 68 <a class="link" href="../generator_concepts/unarygenerator.html" title="UnaryGenerator"><code class="computeroutput"><span class="identifier">UnaryGenerator</span></code></a> 69 </p></blockquote></div> 70<div class="variablelist"> 71<p class="title"><b>Notation</b></p> 72<dl class="variablelist"> 73<dt><span class="term"><code class="computeroutput"><span class="identifier">a</span></code></span></dt> 74<dd><p> 75 A generator object 76 </p></dd> 77<dt><span class="term"><code class="computeroutput"><span class="identifier">A</span></code></span></dt> 78<dd><p> 79 Attribute type of generator <code class="computeroutput"><span class="identifier">a</span></code> 80 </p></dd> 81</dl> 82</div> 83<h6> 84<a name="spirit.karma.reference.directive.duplicate.h3"></a> 85 <span class="phrase"><a name="spirit.karma.reference.directive.duplicate.expression_semantics"></a></span><a class="link" href="duplicate.html#spirit.karma.reference.directive.duplicate.expression_semantics">Expression 86 Semantics</a> 87 </h6> 88<p> 89 Semantics of an expression is defined only where it differs from, or 90 is not defined in <a class="link" href="../generator_concepts/unarygenerator.html" title="UnaryGenerator"><code class="computeroutput"><span class="identifier">UnaryGenerator</span></code></a>. 91 </p> 92<div class="informaltable"><table class="table"> 93<colgroup> 94<col> 95<col> 96</colgroup> 97<thead><tr> 98<th> 99 <p> 100 Expression 101 </p> 102 </th> 103<th> 104 <p> 105 Semantics 106 </p> 107 </th> 108</tr></thead> 109<tbody><tr> 110<td> 111 <p> 112 <code class="computeroutput"><span class="identifier">duplicate</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> 113 </p> 114 </td> 115<td> 116 <p> 117 The <code class="computeroutput"><span class="identifier">duplicate</span></code> 118 directive duplicates the supplied attribute for all elements 119 of a embedded sequence generator. For all other types of embedded 120 generators it has no effect. It succeeds as long as its embedded 121 generator does not fail. 122 </p> 123 </td> 124</tr></tbody> 125</table></div> 126<h6> 127<a name="spirit.karma.reference.directive.duplicate.h4"></a> 128 <span class="phrase"><a name="spirit.karma.reference.directive.duplicate.attributes"></a></span><a class="link" href="duplicate.html#spirit.karma.reference.directive.duplicate.attributes">Attributes</a> 129 </h6> 130<p> 131 See <a class="link" href="../../quick_reference/compound_attribute_rules.html#spirit.karma.quick_reference.compound_attribute_rules.notation">Compound 132 Attribute Notation</a>. 133 </p> 134<div class="informaltable"><table class="table"> 135<colgroup> 136<col> 137<col> 138</colgroup> 139<thead><tr> 140<th> 141 <p> 142 Expression 143 </p> 144 </th> 145<th> 146 <p> 147 Attribute 148 </p> 149 </th> 150</tr></thead> 151<tbody><tr> 152<td> 153 <p> 154 <code class="computeroutput"><span class="identifier">duplicate</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> 155 </p> 156 </td> 157<td> 158 <p> 159</p> 160<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--></span> <span class="identifier">duplicate</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">A</span> 161<span class="identifier">a</span><span class="special">:</span> <span class="identifier">tuple</span><span class="special"><</span><span class="identifier">A</span><span class="special">,</span> <span class="identifier">A</span><span class="special">,</span> <span class="special">...></span> <span class="special">--></span> <span class="identifier">duplicate</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">A</span> 162<span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="identifier">duplicate</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre> 163<p> 164 </p> 165 </td> 166</tr></tbody> 167</table></div> 168<p> 169 If the embedded generator of the <code class="computeroutput"><span class="identifier">duplicate</span><span class="special">[]</span></code> directive is a sequence it is expected 170 that all elements of this sequence expose either the same attribute type, 171 an compatible attribute type, or <code class="computeroutput"><span class="identifier">unused</span></code>. 172 In this case, the <code class="computeroutput"><span class="identifier">duplicate</span><span class="special">[]</span></code> directive exposes the attribute type 173 of its first element. The behavior of the <code class="computeroutput"><span class="identifier">duplicate</span><span class="special">[]</span></code> directive is undefined if the elements 174 of an embedded sequence do not expose the same attributes. Most likely, 175 the corresponding expression will not compile. 176 </p> 177<h6> 178<a name="spirit.karma.reference.directive.duplicate.h5"></a> 179 <span class="phrase"><a name="spirit.karma.reference.directive.duplicate.complexity"></a></span><a class="link" href="duplicate.html#spirit.karma.reference.directive.duplicate.complexity">Complexity</a> 180 </h6> 181<div class="blockquote"><blockquote class="blockquote"><p> 182 The overall complexity of the <code class="computeroutput"><span class="identifier">duplicate</span><span class="special">[]</span></code> directive depends on the complexity 183 of the embedded generator. 184 </p></blockquote></div> 185<h6> 186<a name="spirit.karma.reference.directive.duplicate.h6"></a> 187 <span class="phrase"><a name="spirit.karma.reference.directive.duplicate.example"></a></span><a class="link" href="duplicate.html#spirit.karma.reference.directive.duplicate.example">Example</a> 188 </h6> 189<div class="note"><table border="0" summary="Note"> 190<tr> 191<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> 192<th align="left">Note</th> 193</tr> 194<tr><td align="left" valign="top"><p> 195 The test harness for the example(s) below is presented in the <a class="link" href="../basics.html#spirit.karma.reference.basics.examples">Basics Examples</a> 196 section. 197 </p></td></tr> 198</table></div> 199<p> 200 Some includes: 201 </p> 202<p> 203</p> 204<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">karma</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 205<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">support_utree</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 206<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">phoenix_core</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 207<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">phoenix_operator</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 208<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">std_pair</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 209<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> 210<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">string</span><span class="special">></span> 211</pre> 212<p> 213 </p> 214<p> 215 Some using declarations: 216 </p> 217<p> 218</p> 219<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">double_</span><span class="special">;</span> 220<span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">duplicate</span><span class="special">;</span> 221<span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">space</span><span class="special">;</span> 222</pre> 223<p> 224 </p> 225<p> 226 Basic usage of the <code class="computeroutput"><span class="identifier">duplicate</span></code> 227 generators: 228 </p> 229<p> 230</p> 231<pre class="programlisting"><span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"2.02.0"</span><span class="special">,</span> <span class="identifier">duplicate</span><span class="special">[</span><span class="identifier">double_</span> <span class="special"><<</span> <span class="identifier">double_</span><span class="special">],</span> <span class="number">2.0</span><span class="special">);</span> 232<span class="identifier">test_generator_attr_delim</span><span class="special">(</span><span class="string">"2.0 2.0 "</span><span class="special">,</span> <span class="identifier">duplicate</span><span class="special">[</span><span class="identifier">double_</span> <span class="special"><<</span> <span class="identifier">double_</span><span class="special">],</span> <span class="identifier">space</span><span class="special">,</span> <span class="number">2.0</span><span class="special">);</span> 233</pre> 234<p> 235 </p> 236</div> 237<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 238<td align="left"></td> 239<td align="right"><div class="copyright-footer">Copyright © 2001-2011 Joel de Guzman, Hartmut Kaiser<p> 240 Distributed under the Boost Software License, Version 1.0. (See accompanying 241 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>) 242 </p> 243</div></td> 244</tr></table> 245<hr> 246<div class="spirit-nav"> 247<a accesskey="p" href="omit.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../directive.html"><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="columns.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 248</div> 249</body> 250</html> 251
