Google Git
Sign in
nest-open-source / nest-learning-thermostat / 5.0 / boost / 317601cb979f96545d0e892ce7cfdf59f676ee0a / . / boost_1_45_0 / libs / fusion / doc / html / fusion / algorithm / iteration / functions / iter_fold.html
blob: 9d945a6526e0cc89315c27530ed33cbaa083ebc8 [file] [log] [blame]
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>iter_fold</title>
<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
<link rel="home" href="../../../../index.html" title="Chapter&#160;1.&#160;Fusion 2.0">
<link rel="up" href="../functions.html" title="Functions">
<link rel="prev" href="reverse_fold.html" title="reverse_fold">
<link rel="next" href="reverse_iter_fold.html" title="reverse_iter_fold">
</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="../../../../../../../../libs/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="reverse_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="reverse_iter_fold.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="fusion.algorithm.iteration.functions.iter_fold"></a><a class="link" href="iter_fold.html" title="iter_fold">iter_fold</a>
</h5></div></div></div>
<a name="fusion.algorithm.iteration.functions.iter_fold.description"></a><h6>
<a name="id990893"></a>
<a class="link" href="iter_fold.html#fusion.algorithm.iteration.functions.iter_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">iter_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 iterators on each element of <code class="computeroutput"><span class="identifier">seq</span></code>.
</p>
<a name="fusion.algorithm.iteration.functions.iter_fold.synopsis"></a><h6>
<a name="id990969"></a>
<a class="link" href="iter_fold.html#fusion.algorithm.iteration.functions.iter_fold.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 class="link" href="../metafunctions/iter_fold.html" title="iter_fold"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">iter_fold</span></code></a><span class="special">&lt;</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">&gt;::</span><span class="identifier">type</span> iter_fold<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="identifier">f</span><span class="special">);</span>
<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 class="link" href="../metafunctions/iter_fold.html" title="iter_fold"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">iter_fold</span></code></a><span class="special">&lt;</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">&gt;::</span><span class="identifier">type</span> iter_fold<span class="special">(</span>
<span class="identifier">Sequence</span> <span class="keyword">const</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="identifier">f</span><span class="special">);</span>
</pre>
<div class="table">
<a name="id991318"></a><p class="title"><b>Table&#160;1.39.&#160;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>
</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>it<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">&lt;</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">S</span><span class="special">,</span>It<span class="special">)&gt;::</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 iterator <code class="computeroutput"><span class="identifier">it</span></code>
of type <code class="computeroutput"><span class="identifier">It</span></code>
on an element of <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.iter_fold.expression_semantics"></a><h6>
<a name="id991575"></a>
<a class="link" href="iter_fold.html#fusion.algorithm.iteration.functions.iter_fold.expression_semantics">Expression
Semantics</a>
</h6>
<pre class="programlisting">iter_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,it1),it2) ...itN)</code> where <code class="literal">it1 ...itN</code>
are consecutive iterators on the elements of <code class="computeroutput"><span class="identifier">seq</span></code>.
</p>
<a name="fusion.algorithm.iteration.functions.iter_fold.complexity"></a><h6>
<a name="id991659"></a>
<a class="link" href="iter_fold.html#fusion.algorithm.iteration.functions.iter_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">&lt;</span><span class="identifier">Sequence</span><span class="special">&gt;::</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.iter_fold.header"></a><h6>
<a name="id991719"></a>
<a class="link" href="iter_fold.html#fusion.algorithm.iteration.functions.iter_fold.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>iter_fold<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>iter_fold<span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<a name="fusion.algorithm.iteration.functions.iter_fold.example"></a><h6>
<a name="id993741"></a>
<a class="link" href="iter_fold.html#fusion.algorithm.iteration.functions.iter_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">&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">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="identifier">T</span><span class="special">&amp;</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">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&gt;(</span><a class="link" href="../../../iterator/functions/deref.html" title="deref"><code class="computeroutput"><span class="identifier">deref</span></code></a>(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">&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>iter_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> "12"<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 &#169; 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="reverse_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="reverse_iter_fold.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>