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| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="spirit.karma.reference.operator.sequence"></a><a class="link" href="sequence.html" title="Sequences (a << b)">Sequences |
| (<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.sequence.description"></a><h6> |
| <a name="id1087199"></a> |
| <a class="link" href="sequence.html#spirit.karma.reference.operator.sequence.description">Description</a> |
| </h6> |
| <p> |
| Generator sequences are used to consecutively combine different, more |
| primitive generators. All generators in a sequence are invoked from left |
| to right as long as they succeed. |
| </p> |
| <a name="spirit.karma.reference.operator.sequence.header"></a><h6> |
| <a name="id1087215"></a> |
| <a class="link" href="sequence.html#spirit.karma.reference.operator.sequence.header">Header</a> |
| </h6> |
| <pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/karma/operator/sequence.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_sequence</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.sequence.model_of"></a><h6> |
| <a name="id1087290"></a> |
| <a class="link" href="sequence.html#spirit.karma.reference.operator.sequence.model_of">Model |
| of</a> |
| </h6> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <a class="link" href="../generator_concepts/narygenerator.html" title="NaryGenerator"><code class="computeroutput"><span class="identifier">NaryGenerator</span></code></a> |
| </p></blockquote></div> |
| <a name="spirit.karma.reference.operator.sequence.expression_semantics"></a><h6> |
| <a name="id1087322"></a> |
| <a class="link" href="sequence.html#spirit.karma.reference.operator.sequence.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/narygenerator.html" title="NaryGenerator"><code class="computeroutput"><span class="identifier">NaryGenerator</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 generators <code class="computeroutput"><span class="identifier">a</span></code> |
| and <code class="computeroutput"><span class="identifier">b</span></code> are executed |
| sequentially from left to right and as long as they succeed. |
| A failed generator stops the execution of the entire sequence |
| and makes the sequence fail as well. |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <p> |
| It is important to note, that sequences don't perform any buffering of |
| the output generated by its elements. That means that any failing sequence |
| might have already generated some output, which is <span class="emphasis"><em>not</em></span> |
| rolled back. |
| </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> |
| The simplest way to force a sequence to behave as if it did buffering |
| is to wrap it into a buffering directive (see <a class="link" href="../directive/buffer.html" title="Temporary Output Buffering (buffer[])"><code class="computeroutput"><span class="identifier">buffer</span></code></a>): |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">buffer</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">c</span><span class="special">]</span></pre> |
| <p> |
| </p> |
| <p> |
| which will <span class="emphasis"><em>not</em></span> generate any output in case of |
| a failing sequence. |
| </p> |
| </td></tr> |
| </table></div> |
| <a name="spirit.karma.reference.operator.sequence.attributes"></a><h6> |
| <a name="id1087507"></a> |
| <a class="link" href="sequence.html#spirit.karma.reference.operator.sequence.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> (sequence) |
| </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">tuple</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">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">Unused</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">A</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">B</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">Unused</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> |
| |
| <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">A</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">vector</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">A</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">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="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">vector</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="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></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">tuple</span><span class="special"><</span><span class="identifier">A</span><span class="special">,</span> <span class="identifier">B</span><span class="special">></span></code> and <code class="computeroutput"><span class="identifier">vector</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span></code> as placeholders only. |
| </p> |
| <p> |
| The notation <code class="computeroutput"><span class="identifier">tuple</span><span class="special"><</span><span class="identifier">A</span><span class="special">,</span> <span class="identifier">B</span><span class="special">></span></code> stands for <span class="emphasis"><em>any fusion |
| sequence of two elements</em></span>, where <code class="computeroutput"><span class="identifier">A</span></code> |
| is the type of its first element and <code class="computeroutput"><span class="identifier">B</span></code> |
| is the type of its second element. |
| </p> |
| <p> |
| 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 attribute composition and propagation rules as shown in the table |
| above make sequences somewhat special as they can operate in two modes |
| if all elements have the same attribute type: consuming fusion sequences |
| and consuming STL containers. The selected mode depends on the type of |
| the attribute supplied. |
| </p> |
| <a name="spirit.karma.reference.operator.sequence.complexity"></a><h6> |
| <a name="id1088328"></a> |
| <a class="link" href="sequence.html#spirit.karma.reference.operator.sequence.complexity">Complexity</a> |
| </h6> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| The overall complexity of the sequence generator is defined by the |
| sum of the complexities of its elements. The complexity of the sequence |
| itself is O(N), where N is the number of elements in the sequence. |
| </p></blockquote></div> |
| <a name="spirit.karma.reference.operator.sequence.example"></a><h6> |
| <a name="id1088348"></a> |
| <a class="link" href="sequence.html#spirit.karma.reference.operator.sequence.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 sequence: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><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">double_</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="number">1.0</span><span class="special">,</span> <span class="number">2.0</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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