<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>accumulate</title> <link rel="stylesheet" href="../../../../../../../../doc/html/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.1"> <link rel="home" href="../../../../index.html" title="Chapter 1. Fusion 2.0"> <link rel="up" href="../functions.html" title="Functions"> <link rel="prev" href="fold.html" title="fold"> <link rel="next" href="for_each.html" title="for_each"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> <td align="center"><a href="../../../../../../../../index.html">Home</a></td> <td align="center"><a href="../../../../../../../libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="fold.html"><img src="../../../../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../functions.html"><img src="../../../../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="for_each.html"><img src="../../../../../../../../doc/html/images/next.png" alt="Next"></a> </div> <div class="section" title="accumulate"> <div class="titlepage"><div><div><h5 class="title"> <a name="fusion.algorithm.iteration.functions.accumulate"></a><a class="link" href="accumulate.html" title="accumulate">accumulate</a> </h5></div></div></div> <a name="fusion.algorithm.iteration.functions.accumulate.description"></a><h6> <a name="id745856"></a> <a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.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>, accumulate 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.accumulate.synopsis"></a><h6> <a name="id745930"></a> <a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.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/accumulate.html" title="accumulate"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">accumulate</span></code></a><span class="special"><</span><span class="identifier">Sequence</span><span class="special">,</span> <span class="identifier">State</span><span class="special">,</span> <span class="identifier">F</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">accumulate</span><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="keyword">const</span><span class="special">&</span> <span class="identifier">f</span><span class="special">);</span> </pre> <div class="table"> <a name="id746116"></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/forward_sequence.html" title="Forward Sequence">Forward Sequence</a>, <code class="computeroutput"><span class="identifier">f</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span><span class="identifier">e</span><span class="special">)</span></code> must be a valid expression for current state <code class="computeroutput"><span class="identifier">s</span></code>, and each element <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> <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"><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><span class="identifier">E</span><span class="special">)>::</span><span class="identifier">type</span></code> is the return type of <code class="computeroutput"><span class="identifier">f</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span><span class="identifier">e</span><span class="special">)</span></code> 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.accumulate.expression_semantics"></a><h6> <a name="id746416"></a> <a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.expression_semantics">Expression Semantics</a> </h6> <pre class="programlisting"><span class="identifier">accumulate</span><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="computeroutput"><span class="identifier">f</span><span class="special">(...</span> <span class="identifier">f</span><span class="special">(</span><span class="identifier">f</span><span class="special">(</span><span class="identifier">initial_state</span><span class="special">,</span><span class="identifier">e1</span><span class="special">),</span><span class="identifier">e2</span><span class="special">)</span> <span class="special">...</span><span class="identifier">eN</span><span class="special">)</span></code> where <code class="computeroutput"><span class="identifier">e1</span> <span class="special">...</span><span class="identifier">eN</span></code> are the elements of <code class="computeroutput"><span class="identifier">seq</span></code>. </p> <a name="fusion.algorithm.iteration.functions.accumulate.complexity"></a><h6> <a name="id746568"></a> <a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.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.accumulate.header"></a><h6> <a name="id746628"></a> <a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.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><span class="identifier">accumulate</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">accumulate</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> </pre> <a name="fusion.algorithm.iteration.functions.accumulate.example"></a><h6> <a name="id746743"></a> <a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.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><span class="identifier">t</span><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><a class="link" href="accumulate.html" title="accumulate"><code class="computeroutput"><span class="identifier">accumulate</span></code></a><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> <span class="string">"12"</span><span class="special">);</span> </pre> </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 © 2001-2007 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> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="fold.html"><img src="../../../../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../functions.html"><img src="../../../../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="for_each.html"><img src="../../../../../../../../doc/html/images/next.png" alt="Next"></a> </div> </body> </html>