1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Parser Directive Ignoring Attribute (omit[])</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="Parser Directives"> 9<link rel="prev" href="no_case.html" title="Parser Directive Inhibiting Case Sensitivity (no_case[])"> 10<link rel="next" href="raw.html" title="Directive for Transduction Parsing (raw[])"> 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 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title="Parser Directive Ignoring Attribute (omit[])">Parser Directive 28 Ignoring Attribute (<code class="computeroutput"><span class="identifier">omit</span><span class="special">[]</span></code>)</a> 29</h5></div></div></div> 30<h6> 31<a name="spirit.qi.reference.directive.omit.h0"></a> 32 <span class="phrase"><a name="spirit.qi.reference.directive.omit.description"></a></span><a class="link" href="omit.html#spirit.qi.reference.directive.omit.description">Description</a> 33 </h6> 34<p> 35 The <code class="computeroutput"><span class="identifier">omit</span><span class="special">[]</span></code> 36 ignores the attribute of its subject parser replacing it with <code class="computeroutput"><span class="identifier">unused</span></code>. 37 </p> 38<h6> 39<a name="spirit.qi.reference.directive.omit.h1"></a> 40 <span class="phrase"><a name="spirit.qi.reference.directive.omit.header"></a></span><a class="link" href="omit.html#spirit.qi.reference.directive.omit.header">Header</a> 41 </h6> 42<pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/qi/directive/omit.hpp></span> 43<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">qi_omit</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 44</pre> 45<p> 46 Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>. 47 </p> 48<h6> 49<a name="spirit.qi.reference.directive.omit.h2"></a> 50 <span class="phrase"><a name="spirit.qi.reference.directive.omit.namespace"></a></span><a class="link" href="omit.html#spirit.qi.reference.directive.omit.namespace">Namespace</a> 51 </h6> 52<div class="informaltable"><table class="table"> 53<colgroup><col></colgroup> 54<thead><tr><th> 55 <p> 56 Name 57 </p> 58 </th></tr></thead> 59<tbody><tr><td> 60 <p> 61 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">omit</span> <span class="comment">// alias: 62 boost::spirit::qi::omit</span></code> 63 </p> 64 </td></tr></tbody> 65</table></div> 66<h6> 67<a name="spirit.qi.reference.directive.omit.h3"></a> 68 <span class="phrase"><a name="spirit.qi.reference.directive.omit.model_of"></a></span><a class="link" href="omit.html#spirit.qi.reference.directive.omit.model_of">Model 69 of</a> 70 </h6> 71<div class="blockquote"><blockquote class="blockquote"><p> 72 <a class="link" href="../parser_concepts/unaryparser.html" title="UnaryParser"><code class="computeroutput"><span class="identifier">UnaryParser</span></code></a> 73 </p></blockquote></div> 74<div class="variablelist"> 75<p class="title"><b>Notation</b></p> 76<dl class="variablelist"> 77<dt><span class="term"><code class="computeroutput"><span class="identifier">a</span></code></span></dt> 78<dd><p> 79 A <a class="link" href="../parser_concepts/parser.html" title="Parser"><code class="computeroutput"><span class="identifier">Parser</span></code></a>. 80 </p></dd> 81</dl> 82</div> 83<h6> 84<a name="spirit.qi.reference.directive.omit.h4"></a> 85 <span class="phrase"><a name="spirit.qi.reference.directive.omit.expression_semantics"></a></span><a class="link" href="omit.html#spirit.qi.reference.directive.omit.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="../parser_concepts/unaryparser.html" title="UnaryParser"><code class="computeroutput"><span class="identifier">UnaryParser</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">omit</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> 113 </p> 114 </td> 115<td> 116 <p> 117 Ignore the attribute of the subject parser, <code class="computeroutput"><span class="identifier">a</span></code> 118 </p> 119 </td> 120</tr></tbody> 121</table></div> 122<h6> 123<a name="spirit.qi.reference.directive.omit.h5"></a> 124 <span class="phrase"><a name="spirit.qi.reference.directive.omit.attributes"></a></span><a class="link" href="omit.html#spirit.qi.reference.directive.omit.attributes">Attributes</a> 125 </h6> 126<div class="informaltable"><table class="table"> 127<colgroup> 128<col> 129<col> 130</colgroup> 131<thead><tr> 132<th> 133 <p> 134 Expression 135 </p> 136 </th> 137<th> 138 <p> 139 Attribute 140 </p> 141 </th> 142</tr></thead> 143<tbody><tr> 144<td> 145 <p> 146 <code class="computeroutput"><span class="identifier">omit</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> 147 </p> 148 </td> 149<td> 150 <p> 151 <code class="computeroutput"><span class="identifier">unused_type</span></code> 152 </p> 153 </td> 154</tr></tbody> 155</table></div> 156<h6> 157<a name="spirit.qi.reference.directive.omit.h6"></a> 158 <span class="phrase"><a name="spirit.qi.reference.directive.omit.complexity"></a></span><a class="link" href="omit.html#spirit.qi.reference.directive.omit.complexity">Complexity</a> 159 </h6> 160<div class="blockquote"><blockquote class="blockquote"><p> 161 The complexity is defined by the complexity of the subject parser, 162 <code class="computeroutput"><span class="identifier">a</span></code> 163 </p></blockquote></div> 164<h6> 165<a name="spirit.qi.reference.directive.omit.h7"></a> 166 <span class="phrase"><a name="spirit.qi.reference.directive.omit.example"></a></span><a class="link" href="omit.html#spirit.qi.reference.directive.omit.example">Example</a> 167 </h6> 168<div class="note"><table border="0" summary="Note"> 169<tr> 170<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> 171<th align="left">Note</th> 172</tr> 173<tr><td align="left" valign="top"><p> 174 The test harness for the example(s) below is presented in the <a class="link" href="../basics.html#spirit.qi.reference.basics.examples">Basics Examples</a> 175 section. 176 </p></td></tr> 177</table></div> 178<p> 179 Some using declarations: 180 </p> 181<p> 182</p> 183<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">qi</span><span class="special">::</span><span class="identifier">omit</span><span class="special">;</span> 184<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">qi</span><span class="special">::</span><span class="identifier">int_</span><span class="special">;</span> 185<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">ascii</span><span class="special">::</span><span class="identifier">char_</span><span class="special">;</span> 186</pre> 187<p> 188 </p> 189<p> 190 This parser ignores the first two characters and extracts the succeeding 191 <code class="computeroutput"><span class="keyword">int</span></code>: 192 </p> 193<p> 194</p> 195<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">i</span><span class="special">;</span> 196<span class="identifier">test_parser_attr</span><span class="special">(</span><span class="string">"xx345"</span><span class="special">,</span> <span class="identifier">omit</span><span class="special">[</span><span class="identifier">char_</span> <span class="special">>></span> <span class="identifier">char_</span><span class="special">]</span> <span class="special">>></span> <span class="identifier">int_</span><span class="special">,</span> <span class="identifier">i</span><span class="special">);</span> 197<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">i</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// should print 345</span> 198</pre> 199<p> 200 </p> 201</div> 202<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 203<td align="left"></td> 204<td align="right"><div class="copyright-footer">Copyright © 2001-2011 Joel de Guzman, Hartmut Kaiser<p> 205 Distributed under the Boost Software License, Version 1.0. (See accompanying 206 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>) 207 </p> 208</div></td> 209</tr></table> 210<hr> 211<div class="spirit-nav"> 212<a accesskey="p" href="no_case.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="raw.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 213</div> 214</body> 215</html> 216
