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Regenerating/reorganizing docs [SVN r40832]
2007-11-06 12:13:52 +00:00
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<title>accumulate</title>
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<div class="section" lang="en">
<div class="titlepage"><div><div><h5 class="title">
<a name="fusion.algorithm.iteration.functions.accumulate"></a><a href="accumulate.html" title="accumulate">accumulate</a></h5></div></div></div>
<a name="fusion.algorithm.iteration.functions.accumulate.description"></a><h6>
<a name="id577137"></a>
<a href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.description">Description</a>
</h6>
<p>
For a sequence <tt class="computeroutput"><span class="identifier">Seq</span></tt>, initial
state, and binary function object or function pointer <tt class="computeroutput"><span class="identifier">f</span></tt>,
accumulate repeatedly applies binary <tt class="computeroutput"><span class="identifier">f</span></tt>
to each element of <tt class="computeroutput"><span class="identifier">Seq</span></tt>
and the previous state.
</p>
<a name="fusion.algorithm.iteration.functions.accumulate.synopsis"></a><h6>
<a name="id577217"></a>
<a href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.synopsis">Synopsis</a>
</h6>
<pre class="programlisting">
<span class="keyword">template</span><span class="special">&lt;</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">&gt;</span>
<span class="keyword">typename</span> <a href="../metafunctions/accumulate.html" title="accumulate"><tt class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">accumulate</span></tt></a><span class="special">&lt;</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">&gt;::</span><span class="identifier">type</span> <span class="identifier">accumulate</span><span class="special">(</span>
<span class="identifier">Sequence</span><span class="special">&amp;</span> <span class="identifier">seq</span><span class="special">,</span> <span class="identifier">State</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">initial_state</span><span class="special">,</span> <span class="identifier">F</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">f</span><span class="special">);</span>
</pre>
<div class="table">
<a name="id577478"></a><p class="title"><b>Table<EFBFBD>1.34.<2E>Parameters</b></p>
<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>
<tt class="computeroutput"><span class="identifier">seq</span></tt>
</p>
</td>
<td>
<p>
A model of <a href="../../../sequence/concepts/forward_sequence.html" title="Forward
Sequence">Forward
Sequence</a>, <tt class="computeroutput"><span class="identifier">f</span><span class="special">(</span><span class="identifier">eN</span>
<span class="special">....</span><span class="identifier">f</span><span class="special">(</span><span class="identifier">e2</span><span class="special">,</span><span class="identifier">f</span><span class="special">(</span><span class="identifier">e1</span><span class="special">,</span><span class="identifier">initial_state</span><span class="special">)))</span></tt> must be a valid expression for
each element <tt class="computeroutput"><span class="identifier">e1</span></tt>
to <tt class="computeroutput"><span class="identifier">eN</span></tt> in <tt class="computeroutput"><span class="identifier">seq</span></tt>
</p>
</td>
<td>
<p>
Operation's argument
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">initial_state</span></tt>
</p>
</td>
<td>
<p>
Any type
</p>
</td>
<td>
<p>
Initial state
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">f</span></tt>
</p>
</td>
<td>
<p>
<tt class="computeroutput"><a href="http://www.boost.org/libs/utility/utility.htm#result_of" target="_top"><tt class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span></tt></a><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">E</span><span class="special">,</span><span class="identifier">S</span><span class="special">)&gt;::</span><span class="identifier">type</span></tt> is the return type of <tt class="computeroutput"><span class="identifier">f</span><span class="special">(</span><span class="identifier">e</span><span class="special">,</span><span class="identifier">s</span><span class="special">)</span></tt>
for each element <tt class="computeroutput"><span class="identifier">e</span></tt>
of type <tt class="computeroutput"><span class="identifier">E</span></tt> in <tt class="computeroutput"><span class="identifier">seq</span></tt>, and current state <tt class="computeroutput"><span class="identifier">s</span></tt> of type <tt class="computeroutput"><span class="identifier">S</span></tt>
</p>
</td>
<td>
<p>
Operation's argument
</p>
</td>
</tr>
</tbody>
</table>
</div>
<a name="fusion.algorithm.iteration.functions.accumulate.expression_semantics"></a><h6>
<a name="id577930"></a>
<a 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"><b>Return type</b></span>: Any type
</p>
<p>
<span class="bold"><b>Semantics</b></span>: Equivalent to <tt class="computeroutput"><span class="identifier">f</span><span class="special">(</span><span class="identifier">eN</span> <span class="special">....</span><span class="identifier">f</span><span class="special">(</span><span class="identifier">e2</span><span class="special">,</span><span class="identifier">f</span><span class="special">(</span><span class="identifier">e1</span><span class="special">,</span><span class="identifier">initial_state</span><span class="special">)))</span></tt>
where <tt class="computeroutput"><span class="identifier">e1</span> <span class="special">...</span><span class="identifier">eN</span></tt> are the elements of <tt class="computeroutput"><span class="identifier">seq</span></tt>.
</p>
<a name="fusion.algorithm.iteration.functions.accumulate.complexity"></a><h6>
<a name="id578140"></a>
<a href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.complexity">Complexity</a>
</h6>
<p>
Linear, exactly <tt class="computeroutput"><a href="../../../sequence/intrinsic/metafunctions/size.html" title="size"><tt class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">size</span></tt></a><span class="special">&lt;</span><span class="identifier">Sequence</span><span class="special">&gt;::</span><span class="identifier">value</span></tt> applications of <tt class="computeroutput"><span class="identifier">f</span></tt>.
</p>
<a name="fusion.algorithm.iteration.functions.accumulate.header"></a><h6>
<a name="id578237"></a>
<a href="accumulate.html#fusion.algorithm.iteration.functions.accumulate.header">Header</a>
</h6>
<pre class="programlisting">
<span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</span>
</pre>
<a name="fusion.algorithm.iteration.functions.accumulate.example"></a><h6>
<a name="id578407"></a>
<a 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">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</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">T</span><span class="special">&amp;</span> <span class="identifier">t</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">&amp;</span> <span class="identifier">str</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">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&gt;(</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 href="../../../container/vector.html" title="vector"><tt class="computeroutput"><span class="identifier">vector</span></tt></a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">int</span><span class="special">&gt;</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 href="accumulate.html" title="accumulate"><tt class="computeroutput"><span class="identifier">accumulate</span></tt></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>
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