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| <div class="section"> |
| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="spirit.qi.reference.directive.skip"></a><a class="link" href="skip.html" title="Re-Establish Skipping (skip[])">Re-Establish |
| Skipping (<code class="computeroutput"><span class="identifier">skip</span><span class="special">[]</span></code>)</a> |
| </h5></div></div></div> |
| <a name="spirit.qi.reference.directive.skip.description"></a><h6> |
| <a name="id896623"></a> |
| <a class="link" href="skip.html#spirit.qi.reference.directive.skip.description">Description</a> |
| </h6> |
| <p> |
| The <code class="computeroutput"><span class="identifier">skip</span></code> directive is |
| the inverse of <a class="link" href="lexeme.html" title="Inhibiting Skipping (lexeme[])"><code class="computeroutput"><span class="identifier">lexeme</span></code></a> or <a class="link" href="no_skip.html" title="Inhibiting Skipping Without Pre-skip (no_skip[])">`no_skip[</a><code class="computeroutput"><span class="special">].</span> <span class="identifier">While</span> |
| <span class="identifier">the</span> <a class="link" href="lexeme.html" title="Inhibiting Skipping (lexeme[])"><code class="computeroutput"><span class="identifier">lexeme</span></code></a> <span class="identifier">directive</span> |
| <span class="identifier">turns</span> <span class="identifier">off</span> |
| <span class="identifier">white</span> <span class="identifier">space</span> |
| <span class="identifier">skipping</span><span class="special">,</span> |
| <span class="identifier">the</span> </code>skip<code class="computeroutput"> <span class="identifier">directive</span> |
| <span class="identifier">turns</span> <span class="identifier">it</span> |
| <span class="identifier">on</span> <span class="identifier">again</span><span class="special">.</span> <span class="identifier">This</span> <span class="identifier">is</span> <span class="identifier">simply</span> |
| <span class="identifier">done</span> <span class="identifier">by</span> |
| <span class="identifier">wrapping</span> <span class="identifier">the</span> |
| <span class="identifier">parts</span> <span class="identifier">inside</span> |
| <span class="identifier">the</span> </code>skip` directive: |
| </p> |
| <pre class="programlisting"><span class="identifier">skip</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span> |
| </pre> |
| <p> |
| It is also possible to supply a skip parser to the <code class="computeroutput"><span class="identifier">skip</span></code> |
| directive: |
| </p> |
| <pre class="programlisting"><span class="identifier">skip</span><span class="special">(</span><span class="identifier">p</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span> <span class="comment">// Use `p` as a skipper for parsing `a` |
| </span></pre> |
| <p> |
| This makes it possible to: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| Perform localized phrase level parsing while doing character level |
| parsing. |
| </li> |
| <li class="listitem"> |
| Replace the current skipper anywhere with an entirely different skipper |
| while doing phrase level parsing. |
| </li> |
| </ul></div> |
| <a name="spirit.qi.reference.directive.skip.header"></a><h6> |
| <a name="id896887"></a> |
| <a class="link" href="skip.html#spirit.qi.reference.directive.skip.header">Header</a> |
| </h6> |
| <pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/qi/directive/skip.hpp> |
| </span><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_skip</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <p> |
| Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>. |
| </p> |
| <a name="spirit.qi.reference.directive.skip.namespace"></a><h6> |
| <a name="id896961"></a> |
| <a class="link" href="skip.html#spirit.qi.reference.directive.skip.namespace">Namespace</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup><col></colgroup> |
| <thead><tr><th> |
| <p> |
| Name |
| </p> |
| </th></tr></thead> |
| <tbody><tr><td> |
| <p> |
| <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">skip</span> <span class="comment">// alias: |
| boost::spirit::qi::skip</span></code> |
| </p> |
| </td></tr></tbody> |
| </table></div> |
| <a name="spirit.qi.reference.directive.skip.model_of"></a><h6> |
| <a name="id897039"></a> |
| <a class="link" href="skip.html#spirit.qi.reference.directive.skip.model_of">Model of</a> |
| </h6> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <a class="link" href="../parser_concepts/unaryparser.html" title="UnaryParser"><code class="computeroutput"><span class="identifier">UnaryParser</span></code></a> |
| </p></blockquote></div> |
| <div class="variablelist"> |
| <p class="title"><b>Notation</b></p> |
| <dl> |
| <dt><span class="term"><code class="computeroutput"><span class="identifier">a</span></code></span></dt> |
| <dd><p> |
| A <a class="link" href="../parser_concepts/parser.html" title="Parser"><code class="computeroutput"><span class="identifier">Parser</span></code></a>. |
| </p></dd> |
| </dl> |
| </div> |
| <a name="spirit.qi.reference.directive.skip.expression_semantics"></a><h6> |
| <a name="id897105"></a> |
| <a class="link" href="skip.html#spirit.qi.reference.directive.skip.expression_semantics">Expression |
| Semantics</a> |
| </h6> |
| <p> |
| Semantics of an expression is defined only where it differs from, or |
| is not defined in <a class="link" href="../parser_concepts/unaryparser.html" title="UnaryParser"><code class="computeroutput"><span class="identifier">UnaryParser</span></code></a>. |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Expression |
| </p> |
| </th> |
| <th> |
| <p> |
| Semantics |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">skip</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Re-establish the skipper that got inhibited by lexeme or no_skip |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">skip</span><span class="special">(</span><span class="identifier">p</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Use <code class="computeroutput"><span class="identifier">p</span></code> as a |
| skipper for parsing <code class="computeroutput"><span class="identifier">a</span></code> |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit.qi.reference.directive.skip.attributes"></a><h6> |
| <a name="id897260"></a> |
| <a class="link" href="skip.html#spirit.qi.reference.directive.skip.attributes">Attributes</a> |
| </h6> |
| <p> |
| See <a class="link" href="../../quick_reference/compound_attribute_rules.html#spirit.qi.quick_reference.compound_attribute_rules.notation">Compound |
| Attribute Notation</a>. |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Expression |
| </p> |
| </th> |
| <th> |
| <p> |
| Attribute |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">skip</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| |
| </p> |
| <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">skip</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">A</span> |
| <span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="identifier">skip</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre> |
| <p> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">skip</span><span class="special">(</span><span class="identifier">p</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| |
| </p> |
| <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">skip</span><span class="special">(</span><span class="identifier">p</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">A</span> |
| <span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="identifier">skip</span><span class="special">(</span><span class="identifier">p</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre> |
| <p> |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit.qi.reference.directive.skip.complexity"></a><h6> |
| <a name="id897571"></a> |
| <a class="link" href="skip.html#spirit.qi.reference.directive.skip.complexity">Complexity</a> |
| </h6> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| The complexity is defined by the complexity of the subject parser, |
| <code class="computeroutput"><span class="identifier">a</span></code> |
| </p></blockquote></div> |
| <a name="spirit.qi.reference.directive.skip.example"></a><h6> |
| <a name="id897598"></a> |
| <a class="link" href="skip.html#spirit.qi.reference.directive.skip.example">Example</a> |
| </h6> |
| <div class="note"><table border="0" summary="Note"> |
| <tr> |
| <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> |
| <th align="left">Note</th> |
| </tr> |
| <tr><td align="left" valign="top"><p> |
| 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> |
| section. |
| </p></td></tr> |
| </table></div> |
| <p> |
| Some using declarations: |
| </p> |
| <p> |
| |
| </p> |
| <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">skip</span><span class="special">;</span> |
| <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> |
| <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">space</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Simple usage of <code class="computeroutput"><span class="identifier">skip</span><span class="special">[]</span></code>: |
| </p> |
| <p> |
| Explicitly specify a skip parser. This parser parses comma delimited |
| numbers, ignoring spaces. |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">test_parser</span><span class="special">(</span><span class="string">"1, 2, 3, 4, 5"</span><span class="special">,</span> <span class="identifier">skip</span><span class="special">(</span><span class="identifier">space</span><span class="special">)[</span><span class="identifier">int_</span> <span class="special">>></span> <span class="special">*(</span><span class="char">','</span> <span class="special">>></span> <span class="identifier">int_</span><span class="special">)]);</span> |
| </pre> |
| <p> |
| </p> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2001-2010 Joel de Guzman, Hartmut Kaiser<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 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>) |
| </p> |
| </div></td> |
| </tr></table> |
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