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| <div class="section"> |
| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="fusion.algorithm.iteration.functions.reverse_fold"></a><a class="link" href="reverse_fold.html" title="reverse_fold">reverse_fold</a> |
| </h5></div></div></div> |
| <a name="fusion.algorithm.iteration.functions.reverse_fold.description"></a><h6> |
| <a name="id989595"></a> |
| <a class="link" href="reverse_fold.html#fusion.algorithm.iteration.functions.reverse_fold.description">Description</a> |
| </h6> |
| <p> |
| For a sequence <code class="computeroutput"><span class="identifier">seq</span></code>, initial |
| state <code class="computeroutput"><span class="identifier">initial_state</span></code>, |
| and binary function object or function pointer <code class="computeroutput"><span class="identifier">f</span></code>, |
| <code class="literal">reverse_fold</code> returns the result of the repeated application |
| of binary <code class="computeroutput"><span class="identifier">f</span></code> to the result |
| of the previous <code class="computeroutput"><span class="identifier">f</span></code> invocation |
| (<code class="computeroutput"><span class="identifier">inital_state</span></code> if it is |
| the first call) and each element of <code class="computeroutput"><span class="identifier">seq</span></code>. |
| </p> |
| <a name="fusion.algorithm.iteration.functions.reverse_fold.synopsis"></a><h6> |
| <a name="id989674"></a> |
| <a class="link" href="reverse_fold.html#fusion.algorithm.iteration.functions.reverse_fold.synopsis">Synopsis</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> |
| <span class="keyword">typename</span> <span class="identifier">Sequence</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">State</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">F</span> |
| <span class="special">></span> |
| <span class="keyword">typename</span> <a class="link" href="../metafunctions/reverse_fold.html" title="reverse_fold"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">reverse_fold</span></code></a><span class="special"><</span><span class="identifier">Sequence</span><span class="special">,</span> <span class="identifier">State</span> <span class="keyword">const</span><span class="special">,</span> <span class="identifier">F</span><span class="special">>::</span><span class="identifier">type</span> reverse_fold<span class="special">(</span> |
| <span class="identifier">Sequence</span><span class="special">&</span> <span class="identifier">seq</span><span class="special">,</span> <span class="identifier">State</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">initial_state</span><span class="special">,</span> <span class="identifier">F</span> <span class="identifier">f</span><span class="special">);</span> |
| |
| <span class="keyword">template</span><span class="special"><</span> |
| <span class="keyword">typename</span> <span class="identifier">Sequence</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">State</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">F</span> |
| <span class="special">></span> |
| <span class="keyword">typename</span> <a class="link" href="../metafunctions/reverse_fold.html" title="reverse_fold"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">reverse_fold</span></code></a><span class="special"><</span><span class="identifier">Sequence</span> <span class="keyword">const</span><span class="special">,</span> <span class="identifier">State</span> <span class="keyword">const</span><span class="special">,</span> <span class="identifier">F</span><span class="special">>::</span><span class="identifier">type</span> reverse_fold<span class="special">(</span> |
| <span class="identifier">Sequence</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">seq</span><span class="special">,</span> <span class="identifier">State</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">initial_state</span><span class="special">,</span> <span class="identifier">F</span> <span class="identifier">f</span><span class="special">);</span> |
| </pre> |
| <div class="table"> |
| <a name="id990026"></a><p class="title"><b>Table 1.38. Parameters</b></p> |
| <div class="table-contents"><table class="table" summary="Parameters"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Parameter |
| </p> |
| </th> |
| <th> |
| <p> |
| Requirement |
| </p> |
| </th> |
| <th> |
| <p> |
| Description |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">seq</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| A model of <a class="link" href="../../../sequence/concepts/bidirectional_sequence.html" title="Bidirectional Sequence">Bidirectional |
| Sequence</a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Operation's argument |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">initial_state</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Any type |
| </p> |
| </td> |
| <td> |
| <p> |
| Initial state |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">f</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">f</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span>e<span class="special">)</span></code> with return type <code class="computeroutput"><a href="http://www.boost.org/libs/utility/utility.htm#result_of" target="_top"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span></code></a><span class="special"><</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">S</span><span class="special">,</span>E<span class="special">)>::</span><span class="identifier">type</span></code> for current state <code class="computeroutput"><span class="identifier">s</span></code> of type <code class="computeroutput"><span class="identifier">S</span></code>, |
| and for each element <code class="computeroutput"><span class="identifier">e</span></code> |
| of type <code class="computeroutput"><span class="identifier">E</span></code> in |
| <code class="computeroutput"><span class="identifier">seq</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Operation's argument |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <br class="table-break"><a name="fusion.algorithm.iteration.functions.reverse_fold.expression_semantics"></a><h6> |
| <a name="id990282"></a> |
| <a class="link" href="reverse_fold.html#fusion.algorithm.iteration.functions.reverse_fold.expression_semantics">Expression |
| Semantics</a> |
| </h6> |
| <pre class="programlisting">reverse_fold<span class="special">(</span><span class="identifier">seq</span><span class="special">,</span> <span class="identifier">initial_state</span><span class="special">,</span> <span class="identifier">f</span><span class="special">);</span> |
| </pre> |
| <p> |
| <span class="bold"><strong>Return type</strong></span>: Any type |
| </p> |
| <p> |
| <span class="bold"><strong>Semantics</strong></span>: Equivalent to <code class="literal">f(... |
| f(f(initial_state,eN),eN-1) ...e1)</code> where <code class="literal">e1 ...eN</code> |
| are the consecutive elements of <code class="computeroutput"><span class="identifier">seq</span></code>. |
| </p> |
| <a name="fusion.algorithm.iteration.functions.reverse_fold.complexity"></a><h6> |
| <a name="id990365"></a> |
| <a class="link" href="reverse_fold.html#fusion.algorithm.iteration.functions.reverse_fold.complexity">Complexity</a> |
| </h6> |
| <p> |
| Linear, exactly <code class="computeroutput"><a class="link" href="../../../sequence/intrinsic/metafunctions/size.html" title="size"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">size</span></code></a><span class="special"><</span><span class="identifier">Sequence</span><span class="special">>::</span><span class="identifier">value</span></code> applications of <code class="computeroutput"><span class="identifier">f</span></code>. |
| </p> |
| <a name="fusion.algorithm.iteration.functions.reverse_fold.header"></a><h6> |
| <a name="id990428"></a> |
| <a class="link" href="reverse_fold.html#fusion.algorithm.iteration.functions.reverse_fold.header">Header</a> |
| </h6> |
| <pre class="programlisting"><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">algorithm</span><span class="special">/</span><span class="identifier">iteration</span><span class="special">/</span>reverse_fold<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>reverse_fold<span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <a name="fusion.algorithm.iteration.functions.reverse_fold.example"></a><h6> |
| <a name="id990543"></a> |
| <a class="link" href="reverse_fold.html#fusion.algorithm.iteration.functions.reverse_fold.example">Example</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">make_string</span> |
| <span class="special">{</span> |
| <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">result_type</span><span class="special">;</span> |
| |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="keyword">operator</span><span class="special">()(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&</span> <span class="identifier">str</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">t</span><span class="special">)</span> <span class="keyword">const</span> |
| <span class="special">{</span> |
| <span class="keyword">return</span> <span class="identifier">str</span> <span class="special">+</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lexical_cast</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">>(</span>t<span class="special">);</span> |
| <span class="special">}</span> |
| <span class="special">};</span> |
| <span class="special">...</span> |
| <span class="keyword">const</span> <a class="link" href="../../../container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a><span class="special"><</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">vec</span><span class="special">(</span><span class="number">1</span><span class="special">,</span><span class="number">2</span><span class="special">);</span> |
| <span class="identifier">assert</span><span class="special">(</span>reverse_fold<span class="special">(</span><span class="identifier">vec</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">(</span><span class="string">""</span><span class="special">),</span> <span class="identifier">make_string</span><span class="special">())</span> <span class="special">==</span> "21"<span class="special">);</span> |
| </pre> |
| </div> |
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| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias |
| Schwinger<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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