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| <div class="section"> |
| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="spirit.karma.reference.operator.list"></a><a class="link" href="list.html" title="Lists (a % b)">Lists (<code class="computeroutput"><span class="identifier">a</span> <span class="special">%</span> <span class="identifier">b</span></code>)</a> |
| </h5></div></div></div> |
| <a name="spirit.karma.reference.operator.list.description"></a><h6> |
| <a name="id1093552"></a> |
| <a class="link" href="list.html#spirit.karma.reference.operator.list.description">Description</a> |
| </h6> |
| <p> |
| The list generator is used to repeat the execution of an embedded generator |
| and intersperse it with the output of another generator one or more times. |
| It succeeds if the embedded generator has been successfully executed |
| at least once. |
| </p> |
| <a name="spirit.karma.reference.operator.list.header"></a><h6> |
| <a name="id1093569"></a> |
| <a class="link" href="list.html#spirit.karma.reference.operator.list.header">Header</a> |
| </h6> |
| <pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/karma/operator/list.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">karma_list</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.karma.reference.operator.list.model_of"></a><h6> |
| <a name="id1093644"></a> |
| <a class="link" href="list.html#spirit.karma.reference.operator.list.model_of">Model of</a> |
| </h6> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <a class="link" href="../generator_concepts/binarygenerator.html" title="BinaryGenerator"><code class="computeroutput"><span class="identifier">BinaryGenerator</span></code></a> |
| </p></blockquote></div> |
| <a name="spirit.karma.reference.operator.list.expression_semantics"></a><h6> |
| <a name="id1093678"></a> |
| <a class="link" href="list.html#spirit.karma.reference.operator.list.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="../generator_concepts/binarygenerator.html" title="BinaryGenerator"><code class="computeroutput"><span class="identifier">BinaryGenerator</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">a</span> <span class="special">%</span> |
| <span class="identifier">b</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| The generator <code class="computeroutput"><span class="identifier">a</span></code> |
| is executed one or more times depending on the availability |
| of an attribute. The output generated by <code class="computeroutput"><span class="identifier">a</span></code> |
| is interspersed with the output generated by <code class="computeroutput"><span class="identifier">b</span></code>. The list generator succeeds |
| if its first embedded generator has been successfully executed |
| at least once (unless the underlying output stream reports |
| an error). |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <p> |
| The list expression <code class="computeroutput"><span class="identifier">a</span> <span class="special">%</span> <span class="identifier">b</span></code> |
| is a shortcut for <code class="computeroutput"><span class="identifier">a</span> <span class="special"><<</span> <span class="special">*(</span><span class="identifier">b</span> <span class="special"><<</span> |
| <span class="identifier">a</span><span class="special">)</span></code>. |
| It is almost semantically equivalent, except for the attribute of <code class="computeroutput"><span class="identifier">b</span></code>, which gets ignored in the case of |
| the list generator. |
| </p> |
| <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> |
| All failing iterations of the embedded generator will consume one element |
| from the supplied attribute. The overall <code class="computeroutput"><span class="identifier">a</span> |
| <span class="special">%</span> <span class="identifier">b</span></code> |
| will succeed as long as at least one invocation of the embedded generator, |
| <code class="computeroutput"><span class="identifier">a</span></code>, will succeed (unless |
| the underlying output stream reports an error). |
| </p></td></tr> |
| </table></div> |
| <a name="spirit.karma.reference.operator.list.attributes"></a><h6> |
| <a name="id1093893"></a> |
| <a class="link" href="list.html#spirit.karma.reference.operator.list.attributes">Attributes</a> |
| </h6> |
| <p> |
| See <a class="link" href="../../quick_reference/compound_attribute_rules.html#spirit.karma.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">a</span> <span class="special">%</span> |
| <span class="identifier">b</span></code> (list) |
| </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">b</span><span class="special">:</span> <span class="identifier">B</span> <span class="special">--></span> <span class="special">(</span><span class="identifier">a</span> <span class="special">%</span> <span class="identifier">b</span><span class="special">):</span> <span class="identifier">vector</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="identifier">Unused</span><span class="special">,</span> <span class="identifier">b</span><span class="special">:</span> <span class="identifier">B</span> <span class="special">--></span> <span class="special">(</span><span class="identifier">a</span> <span class="special">%</span> <span class="identifier">b</span><span class="special">):</span> <span class="identifier">Unused</span></pre> |
| <p> |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <div class="important"><table border="0" summary="Important"> |
| <tr> |
| <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../images/important.png"></td> |
| <th align="left">Important</th> |
| </tr> |
| <tr><td align="left" valign="top"><p> |
| The table above uses <code class="computeroutput"><span class="identifier">vector</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span></code> as a placeholder only. The notation |
| of <code class="computeroutput"><span class="identifier">vector</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span></code> |
| stands for <span class="emphasis"><em>any STL container</em></span> holding elements |
| of type <code class="computeroutput"><span class="identifier">A</span></code>. |
| </p></td></tr> |
| </table></div> |
| <p> |
| The list generator will execute its embedded generator once for each |
| element in the provided container attribute and as long as the embedded |
| generator succeeds. The output generated by its first generator will |
| be interspersed by the output generated by the second generator. On each |
| iteration it will pass the next consecutive element from the container |
| attribute to the first embedded generator. The second embedded generator |
| does not get passed any attributes (it gets invoked using an <code class="computeroutput"><span class="identifier">unused_type</span></code> as its attribute). Therefore |
| the number of iterations will not be larger than the number of elements |
| in the container passed as its attribute. An empty container will make |
| the list generator fail. |
| </p> |
| <div class="tip"><table border="0" summary="Tip"> |
| <tr> |
| <td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../images/tip.png"></td> |
| <th align="left">Tip</th> |
| </tr> |
| <tr><td align="left" valign="top"> |
| <p> |
| If you want to use the list generator and still allow for an empty |
| attribute, you can use the optional operator (see <a class="link" href="optional.html" title="Optional (-a)">Optional |
| (unary <code class="computeroutput"><span class="special">-</span></code>)</a>): |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="special">-(</span><span class="identifier">a</span> <span class="special">%</span> <span class="identifier">b</span><span class="special">)</span></pre> |
| <p> |
| </p> |
| <p> |
| which will succeed even if the provided container attribute does not |
| contain any elements. |
| </p> |
| </td></tr> |
| </table></div> |
| <a name="spirit.karma.reference.operator.list.complexity"></a><h6> |
| <a name="id1094238"></a> |
| <a class="link" href="list.html#spirit.karma.reference.operator.list.complexity">Complexity</a> |
| </h6> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| The overall complexity of the list generator is defined by the complexity |
| of its embedded generators multiplied by the number of executed iterations. |
| The complexity of the list generator itself is O(N), where N is the |
| number of elements in the container passed as its attribute. |
| </p></blockquote></div> |
| <a name="spirit.karma.reference.operator.list.example"></a><h6> |
| <a name="id1094258"></a> |
| <a class="link" href="list.html#spirit.karma.reference.operator.list.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="../karma_basics.html#spirit.karma.reference.karma_basics.examples">Basics Examples</a> |
| section. |
| </p></td></tr> |
| </table></div> |
| <p> |
| Some includes: |
| </p> |
| <p> |
| |
| </p> |
| <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> |
| <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> |
| <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> |
| <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> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">string</span><span class="special">></span> |
| </pre> |
| <p> |
| </p> |
| <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">karma</span><span class="special">::</span><span class="identifier">double_</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Basic usage of a list generator: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">double</span><span class="special">></span> <span class="identifier">v1</span><span class="special">;</span> |
| <span class="identifier">v1</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">1.0</span><span class="special">);</span> |
| <span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"1.0"</span><span class="special">,</span> <span class="identifier">double_</span> <span class="special">%</span> <span class="char">','</span><span class="special">,</span> <span class="identifier">v1</span><span class="special">);</span> |
| |
| <span class="identifier">v1</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">2.0</span><span class="special">);</span> |
| <span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"1.0,2.0"</span><span class="special">,</span> <span class="identifier">double_</span> <span class="special">%</span> <span class="char">','</span><span class="special">,</span> <span class="identifier">v1</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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