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<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="id939165"></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="id939429"></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="id939503"></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="id939581"></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="id939647"></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="id939802"></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="id940122"></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="id940150"></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>
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<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>
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