1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>accumulate</title> 5<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../../index.html" title="Chapter 1. Fusion 2.2"> 8<link rel="up" href="../functions.html" title="Functions"> 9<link rel="prev" href="reverse_iter_fold.html" title="reverse_iter_fold"> 10<link rel="next" href="for_each.html" title="for_each"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="reverse_iter_fold.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../functions.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="for_each.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h5 class="title"> 27<a name="fusion.algorithm.iteration.functions.accumulate"></a><a class="link" href="accumulate.html" title="accumulate">accumulate</a> 28</h5></div></div></div> 29<h6> 30<a name="fusion.algorithm.iteration.functions.accumulate.h0"></a> 31 <span class="phrase"><a name="fusion.algorithm.iteration.functions.accumulate.description"></a></span><a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.description">Description</a> 32 </h6> 33<p> 34 For a sequence <code class="computeroutput"><span class="identifier">seq</span></code>, initial 35 state <code class="computeroutput"><span class="identifier">initial_state</span></code>, 36 and binary function object or function pointer <code class="computeroutput"><span class="identifier">f</span></code>, 37 <code class="literal">accumulate</code> returns the result of the repeated application 38 of binary <code class="computeroutput"><span class="identifier">f</span></code> to the result 39 of the previous <code class="computeroutput"><span class="identifier">f</span></code> invocation 40 (<code class="computeroutput"><span class="identifier">inital_state</span></code> if it is 41 the first call) and each element of <code class="computeroutput"><span class="identifier">seq</span></code>. 42 </p> 43<h6> 44<a name="fusion.algorithm.iteration.functions.accumulate.h1"></a> 45 <span class="phrase"><a name="fusion.algorithm.iteration.functions.accumulate.synopsis"></a></span><a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.synopsis">Synopsis</a> 46 </h6> 47<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> 48 <span class="keyword">typename</span> <span class="identifier">Sequence</span><span class="special">,</span> 49 <span class="keyword">typename</span> <span class="identifier">State</span><span class="special">,</span> 50 <span class="keyword">typename</span> <span class="identifier">F</span> 51 <span class="special">></span> 52<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="keyword">const</span><span class="special">,</span> <span class="identifier">F</span><span class="special">>::</span><span class="identifier">type</span> accumulate<span class="special">(</span> 53 <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> 54 55<span class="keyword">template</span><span class="special"><</span> 56 <span class="keyword">typename</span> <span class="identifier">Sequence</span><span class="special">,</span> 57 <span class="keyword">typename</span> <span class="identifier">State</span><span class="special">,</span> 58 <span class="keyword">typename</span> <span class="identifier">F</span> 59 <span class="special">></span> 60<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="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> accumulate<span class="special">(</span> 61 <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> 62 63<span class="keyword">template</span><span class="special"><</span> 64 <span class="keyword">typename</span> <span class="identifier">Sequence</span><span class="special">,</span> 65 <span class="keyword">typename</span> <span class="identifier">State</span><span class="special">,</span> 66 <span class="keyword">typename</span> <span class="identifier">F</span> 67 <span class="special">></span> 68<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> accumulate<span class="special">(</span> 69 <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="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> 70 71<span class="keyword">template</span><span class="special"><</span> 72 <span class="keyword">typename</span> <span class="identifier">Sequence</span><span class="special">,</span> 73 <span class="keyword">typename</span> <span class="identifier">State</span><span class="special">,</span> 74 <span class="keyword">typename</span> <span class="identifier">F</span> 75 <span class="special">></span> 76<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="keyword">const</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> accumulate<span class="special">(</span> 77 <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="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> 78</pre> 79<div class="table"> 80<a name="fusion.algorithm.iteration.functions.accumulate.t0"></a><p class="title"><b>Table 1.44. Parameters</b></p> 81<div class="table-contents"><table class="table" summary="Parameters"> 82<colgroup> 83<col> 84<col> 85<col> 86</colgroup> 87<thead><tr> 88<th> 89 <p> 90 Parameter 91 </p> 92 </th> 93<th> 94 <p> 95 Requirement 96 </p> 97 </th> 98<th> 99 <p> 100 Description 101 </p> 102 </th> 103</tr></thead> 104<tbody> 105<tr> 106<td> 107 <p> 108 <code class="computeroutput"><span class="identifier">seq</span></code> 109 </p> 110 </td> 111<td> 112 <p> 113 A model of <a class="link" href="../../../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward 114 Sequence</a> 115 </p> 116 </td> 117<td> 118 <p> 119 Operation's argument 120 </p> 121 </td> 122</tr> 123<tr> 124<td> 125 <p> 126 <code class="computeroutput"><span class="identifier">initial_state</span></code> 127 </p> 128 </td> 129<td> 130 <p> 131 Any type 132 </p> 133 </td> 134<td> 135 <p> 136 Initial state 137 </p> 138 </td> 139</tr> 140<tr> 141<td> 142 <p> 143 <code class="computeroutput"><span class="identifier">f</span></code> 144 </p> 145 </td> 146<td> 147 <p> 148 <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>, 149 and for each element <code class="computeroutput"><span class="identifier">e</span></code> 150 of type <code class="computeroutput"><span class="identifier">E</span></code> in 151 <code class="computeroutput"><span class="identifier">seq</span></code> 152 </p> 153 </td> 154<td> 155 <p> 156 Operation's argument 157 </p> 158 </td> 159</tr> 160</tbody> 161</table></div> 162</div> 163<br class="table-break"><h6> 164<a name="fusion.algorithm.iteration.functions.accumulate.h2"></a> 165 <span class="phrase"><a name="fusion.algorithm.iteration.functions.accumulate.expression_semantics"></a></span><a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.expression_semantics">Expression 166 Semantics</a> 167 </h6> 168<pre class="programlisting">accumulate<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> 169</pre> 170<p> 171 <span class="bold"><strong>Return type</strong></span>: Any type 172 </p> 173<p> 174 <span class="bold"><strong>Semantics</strong></span>: Equivalent to <code class="literal">f(... 175 f(f(initial_state,e1),e2) ...eN)</code> where <code class="literal">e1 ...eN</code> 176 are the consecutive elements of <code class="computeroutput"><span class="identifier">seq</span></code>. 177 </p> 178<h6> 179<a name="fusion.algorithm.iteration.functions.accumulate.h3"></a> 180 <span class="phrase"><a name="fusion.algorithm.iteration.functions.accumulate.complexity"></a></span><a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.complexity">Complexity</a> 181 </h6> 182<p> 183 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>. 184 </p> 185<h6> 186<a name="fusion.algorithm.iteration.functions.accumulate.h4"></a> 187 <span class="phrase"><a name="fusion.algorithm.iteration.functions.accumulate.header"></a></span><a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.header">Header</a> 188 </h6> 189<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>accumulate<span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 190<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>accumulate<span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 191</pre> 192<h6> 193<a name="fusion.algorithm.iteration.functions.accumulate.h5"></a> 194 <span class="phrase"><a name="fusion.algorithm.iteration.functions.accumulate.example"></a></span><a class="link" href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.example">Example</a> 195 </h6> 196<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">make_string</span> 197<span class="special">{</span> 198 <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> 199 200 <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">></span> 201 <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> 202 <span class="special">{</span> 203 <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> 204 <span class="special">}</span> 205<span class="special">};</span> 206<span class="special">...</span> 207<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> 208<span class="identifier">assert</span><span class="special">(</span>accumulate<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> "12"<span class="special">);</span> 209</pre> 210</div> 211<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 212<td align="left"></td> 213<td align="right"><div class="copyright-footer">Copyright © 2001-2006, 2011, 2012 Joel de Guzman, 214 Dan Marsden, Tobias Schwinger<p> 215 Distributed under the Boost Software License, Version 1.0. (See accompanying 216 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>) 217 </p> 218</div></td> 219</tr></table> 220<hr> 221<div class="spirit-nav"> 222<a accesskey="p" href="reverse_iter_fold.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../functions.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="for_each.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 223</div> 224</body> 225</html> 226
