1<?xml version="1.0" encoding="utf-8" ?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6<meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> 7<title>The MPL Reference Manual: reverse_iter_fold</title> 8<link rel="stylesheet" href="../style.css" type="text/css" /> 9</head> 10<body class="docframe refmanual"> 11<table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./reverse-fold.html" class="navigation-link">Prev</a> <a href="./accumulate.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./reverse-fold.html" class="navigation-link">Back</a> <a href="./accumulate.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./iteration-algorithms.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> 12<td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./algorithms.html" class="navigation-link">Algorithms</a> / <a href="./iteration-algorithms.html" class="navigation-link">Iteration Algorithms</a> / <a href="./reverse-iter-fold.html" class="navigation-link">reverse_iter_fold</a></td> 13</tr></table><div class="header-separator"></div> 14<div class="section" id="reverse-iter-fold"> 15<h1><a class="toc-backref" href="./iteration-algorithms.html#id1472">reverse_iter_fold</a></h1> 16<div class="section" id="id519"> 17<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> 18<pre class="literal-block"> 19template< 20 typename Sequence 21 , typename State 22 , typename BackwardOp 23 , typename ForwardOp = <a href="./placeholders.html" class="identifier">_1</a> 24 > 25struct <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a> 26{ 27 typedef <em>unspecified</em> type; 28}; 29</pre> 30</div> 31<div class="section" id="id520"> 32<h3><a class="subsection-title" href="#description" name="description">Description</a></h3> 33<p>Returns the result of the successive application of binary <tt class="literal"><span class="pre">BackwardOp</span></tt> to the 34result of the previous <tt class="literal"><span class="pre">BackwardOp</span></tt> invocation (<tt class="literal"><span class="pre">State</span></tt> if it's the first call) 35and each iterator in the range [<tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a><Sequence>::type</span></tt>, <tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><Sequence>::type</span></tt>) 36in reverse order. If <tt class="literal"><span class="pre">ForwardOp</span></tt> is provided, then it's applied on forward 37traversal to form the result which is passed to the first <tt class="literal"><span class="pre">BackwardOp</span></tt> call.</p> 38</div> 39<div class="section" id="id521"> 40<h3><a class="subsection-title" href="#header" name="header">Header</a></h3> 41<pre class="literal-block"> 42#include <<a href="../../../../boost/mpl/reverse_iter_fold.hpp" class="header">boost/mpl/reverse_iter_fold.hpp</a>> 43</pre> 44</div> 45<div class="section" id="id522"> 46<h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> 47<table border="1" class="docutils table"> 48<colgroup> 49<col width="16%" /> 50<col width="33%" /> 51<col width="51%" /> 52</colgroup> 53<thead valign="bottom"> 54<tr><th class="head">Parameter</th> 55<th class="head">Requirement</th> 56<th class="head">Description</th> 57</tr> 58</thead> 59<tbody valign="top"> 60<tr><td><tt class="literal"><span class="pre">Sequence</span></tt></td> 61<td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td> 62<td>A sequence to iterate.</td> 63</tr> 64<tr><td><tt class="literal"><span class="pre">State</span></tt></td> 65<td>Any type</td> 66<td>The initial state for the first <tt class="literal"><span class="pre">BackwardOp</span></tt> 67/ <tt class="literal"><span class="pre">ForwardOp</span></tt> application.</td> 68</tr> 69<tr><td><tt class="literal"><span class="pre">BackwardOp</span></tt></td> 70<td>Binary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a></td> 71<td>The operation to be executed on backward 72traversal.</td> 73</tr> 74<tr><td><tt class="literal"><span class="pre">ForwardOp</span></tt></td> 75<td>Binary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a></td> 76<td>The operation to be executed on forward 77traversal.</td> 78</tr> 79</tbody> 80</table> 81</div> 82<div class="section" id="id523"> 83<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> 84<p>For any <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a> <tt class="literal"><span class="pre">s</span></tt>, binary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a> <tt class="literal"><span class="pre">backward_op</span></tt> and <tt class="literal"><span class="pre">forward_op</span></tt>, 85and arbitrary type <tt class="literal"><span class="pre">state</span></tt>:</p> 86<pre class="literal-block"> 87typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>< s,state,backward_op >::type t; 88</pre> 89<table class="docutils field-list" frame="void" rules="none"> 90<col class="field-name" /> 91<col class="field-body" /> 92<tbody valign="top"> 93<tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A type.</p> 94</td> 95</tr> 96<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> 97<pre class="literal-block"> 98typedef <a href="./begin.html" class="identifier">begin</a><s>::type i<sub>1</sub>; 99typedef <a href="./next.html" class="identifier">next</a><i<sub>1</sub>>::type i<sub>2</sub>; 100<em>...</em> 101typedef <a href="./next.html" class="identifier">next</a><i<sub>n</sub>>::type last; 102typedef <a href="./apply.html" class="identifier">apply</a><backward_op,state,i<sub>n</sub>>::type state<sub>n</sub>; 103typedef <a href="./apply.html" class="identifier">apply</a><backward_op,state<sub>n</sub>,i<sub>n-1</sub>>::type state<sub>n-1</sub>; 104<em>...</em> 105typedef <a href="./apply.html" class="identifier">apply</a><backward_op,state<sub>2</sub>,i<sub>1</sub>>::type state<sub>1</sub>; 106typedef state<sub>1</sub> t; 107</pre> 108<p class="last">where <tt class="literal"><span class="pre">n</span> <span class="pre">==</span> <span class="pre"><a href="./size.html" class="identifier">size</a><s>::value</span></tt> and <tt class="literal"><span class="pre">last</span></tt> is identical to <tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><s>::type</span></tt>; equivalent 109to <tt class="literal"><span class="pre">typedef</span> <span class="pre">state</span> <span class="pre">t;</span></tt> if <tt class="literal"><span class="pre"><a href="./empty.html" class="identifier">empty</a><s>::value</span> <span class="pre">==</span> <span class="pre">true</span></tt>.</p> 110</td> 111</tr> 112</tbody> 113</table> 114<!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --> 115<pre class="literal-block"> 116typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>< s,state,backward_op,forward_op >::type t; 117</pre> 118<table class="docutils field-list" frame="void" rules="none"> 119<col class="field-name" /> 120<col class="field-body" /> 121<tbody valign="top"> 122<tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A type.</p> 123</td> 124</tr> 125<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> 126<pre class="last literal-block"> 127typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>< 128 Sequence 129 , <a href="./iter-fold.html" class="identifier">iter_fold</a><s,state,forward_op>::type 130 , backward_op 131 >::type t; 132</pre> 133</td> 134</tr> 135</tbody> 136</table> 137</div> 138<div class="section" id="id524"> 139<h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3> 140<p>Linear. Exactly <tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a><s>::value</span></tt> applications of <tt class="literal"><span class="pre">backward_op</span></tt> and <tt class="literal"><span class="pre">forward_op</span></tt>.</p> 141</div> 142<div class="section" id="id525"> 143<h3><a class="subsection-title" href="#example" name="example">Example</a></h3> 144<p>Build a list of iterators to the negative elements in a sequence.</p> 145<pre class="literal-block"> 146typedef <a href="./vector-c.html" class="identifier">vector_c</a><int,5,-1,0,-7,-2,0,-5,4> numbers; 147typedef <a href="./list-c.html" class="identifier">list_c</a><int,-1,-7,-2,-5> negatives; 148typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>< 149 numbers 150 , <a href="./list.html" class="identifier">list</a><> 151 , <a href="./if.html" class="identifier">if_</a>< <a href="./less.html" class="identifier">less</a>< <a href="./deref.html" class="identifier">deref</a><<a href="./placeholders.html" class="identifier">_2</a>>,<a href="./int.html" class="identifier">int_</a><0> >, <a href="./push-front.html" class="identifier">push_front</a><<a href="./placeholders.html" class="identifier">_1</a>,<a href="./placeholders.html" class="identifier">_2</a>>, <a href="./placeholders.html" class="identifier">_1</a> > 152 >::type iters; 153 154<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./equal.html" class="identifier">equal</a>< 155 negatives 156 , <a href="./transform-view.html" class="identifier">transform_view</a>< iters,<a href="./deref.html" class="identifier">deref</a><<a href="./placeholders.html" class="identifier">_1</a>> > 157 > )); 158</pre> 159</div> 160<div class="section" id="id526"> 161<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> 162<p><a class="reference internal" href="./algorithms.html">Algorithms</a>, <a class="reference internal" href="./iter-fold.html">iter_fold</a>, <a class="reference internal" href="./reverse-fold.html">reverse_fold</a>, <a class="reference internal" href="./fold.html">fold</a></p> 163<!-- Algorithms/Iteration Algorithms//accumulate |10 --> 164</div> 165</div> 166 167<div class="footer-separator"></div> 168<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./reverse-fold.html" class="navigation-link">Prev</a> <a href="./accumulate.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./reverse-fold.html" class="navigation-link">Back</a> <a href="./accumulate.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./iteration-algorithms.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> 169<td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> 170Distributed under the Boost Software License, Version 1.0. (See accompanying 171file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body> 172</html> 173