ceph/src/boost/libs/mpl/doc/refmanual/reverse-fold.html

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  11 <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./iter-fold.html" class="navigation-link">Prev</a>&nbsp;<a href="./reverse-iter-fold.html" class="navigation-link">Next</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./iter-fold.html" class="navigation-link">Back</a>&nbsp;<a href="./reverse-iter-fold.html" class="navigation-link">Along</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./iteration-algorithms.html" class="navigation-link">Up</a>&nbsp;<a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</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-fold.html" class="navigation-link">reverse_fold</a></td>
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  14 <div class="section" id="reverse-fold">
  15 <h1><a class="toc-backref" href="./iteration-algorithms.html#id1471">reverse_fold</a></h1>
  16 <div class="section" id="id509">
  17 <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
  18 <pre class="literal-block">
  19 template&lt;
  20       typename Sequence
  21     , typename State
  22     , typename BackwardOp
  23     , typename ForwardOp = <a href="./placeholders.html" class="identifier">_1</a>
  24     &gt;
  25 struct <a href="./reverse-fold.html" class="identifier">reverse_fold</a>
  26 {
  27     typedef <em>unspecified</em> type;
  28 };
  29 </pre>
  30 </div>
  31 <div class="section" id="id510">
  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
  34 result 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)
  35 and every element in the range [<tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a>&lt;Sequence&gt;::type</span></tt>, <tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a>&lt;Sequence&gt;::type</span></tt>) in
  36 reverse order. If <tt class="literal"><span class="pre">ForwardOp</span></tt> is provided, then it is applied on forward
  37 traversal to form the result that is passed to the first <tt class="literal"><span class="pre">BackwardOp</span></tt> call.</p>
  38 </div>
  39 <div class="section" id="id511">
  40 <h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
  41 <pre class="literal-block">
  42 #include &lt;<a href="../../../../boost/mpl/reverse_fold.hpp" class="header">boost/mpl/reverse_fold.hpp</a>&gt;
  43 </pre>
  44 </div>
  45 <div class="section" id="id512">
  46 <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  47 </div>
  48 <div class="section" id="id513">
  49 <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  50 <table border="1" class="docutils table">
  51 <colgroup>
  52 <col width="16%" />
  53 <col width="33%" />
  54 <col width="51%" />
  55 </colgroup>
  56 <thead valign="bottom">
  57 <tr><th class="head">Parameter</th>
  58 <th class="head">Requirement</th>
  59 <th class="head">Description</th>
  60 </tr>
  61 </thead>
  62 <tbody valign="top">
  63 <tr><td><tt class="literal"><span class="pre">Sequence</span></tt></td>
  64 <td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td>
  65 <td>A sequence to iterate.</td>
  66 </tr>
  67 <tr><td><tt class="literal"><span class="pre">State</span></tt></td>
  68 <td>Any type</td>
  69 <td>The initial state for the first <tt class="literal"><span class="pre">BackwardOp</span></tt>
  70 / <tt class="literal"><span class="pre">ForwardOp</span></tt> application.</td>
  71 </tr>
  72 <tr><td><tt class="literal"><span class="pre">BackwardOp</span></tt></td>
  73 <td>Binary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a></td>
  74 <td>The operation to be executed on backward
  75 traversal.</td>
  76 </tr>
  77 <tr><td><tt class="literal"><span class="pre">ForwardOp</span></tt></td>
  78 <td>Binary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a></td>
  79 <td>The operation to be executed on forward
  80 traversal.</td>
  81 </tr>
  82 </tbody>
  83 </table>
  84 </div>
  85 <div class="section" id="id514">
  86 <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  87 <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>,
  88 and arbitrary type <tt class="literal"><span class="pre">state</span></tt>:</p>
  89 <pre class="literal-block">
  90 typedef <a href="./reverse-fold.html" class="identifier">reverse_fold</a>&lt; s,state,backward_op &gt;::type t;
  91 </pre>
  92 <table class="docutils field-list" frame="void" rules="none">
  93 <col class="field-name" />
  94 <col class="field-body" />
  95 <tbody valign="top">
  96 <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A type</p>
  97 </td>
  98 </tr>
  99 <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p>
 100 <pre class="last literal-block">
 101 typedef <a href="./lambda.html" class="identifier">lambda</a>&lt;backward_op&gt;::type op;
 102 typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>&lt;
 103       s
 104     , state
 105     , apply_wrap2&lt; op, <a href="./placeholders.html" class="identifier">_1</a>, <a href="./deref.html" class="identifier">deref</a>&lt;<a href="./placeholders.html" class="identifier">_2</a>&gt; &gt;
 106     &gt;::type t;
 107 </pre>
 108 </td>
 109 </tr>
 110 </tbody>
 111 </table>
 112 <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
 113 <pre class="literal-block">
 114 typedef <a href="./reverse-fold.html" class="identifier">reverse_fold</a>&lt; s,state,backward_op,forward_op &gt;::type t;
 115 </pre>
 116 <table class="docutils field-list" frame="void" rules="none">
 117 <col class="field-name" />
 118 <col class="field-body" />
 119 <tbody valign="top">
 120 <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A type.</p>
 121 </td>
 122 </tr>
 123 <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p>
 124 <pre class="last literal-block">
 125 typedef <a href="./reverse-fold.html" class="identifier">reverse_fold</a>&lt;
 126       Sequence
 127     , <a href="./fold.html" class="identifier">fold</a>&lt;s,state,forward_op&gt;::type
 128     , backward_op
 129     &gt;::type t;
 130 </pre>
 131 </td>
 132 </tr>
 133 </tbody>
 134 </table>
 135 </div>
 136 <div class="section" id="id515">
 137 <h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3>
 138 <p>Linear. Exactly <tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a>&lt;s&gt;::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>
 139 </div>
 140 <div class="section" id="id516">
 141 <h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
 142 <p>Remove non-negative elements from a sequence <a class="footnote-reference" href="#reverse-fold-note" id="id517">[2]</a>.</p>
 143 <pre class="literal-block">
 144 typedef <a href="./list-c.html" class="identifier">list_c</a>&lt;int,5,-1,0,-7,-2,0,-5,4&gt; numbers;
 145 typedef <a href="./list-c.html" class="identifier">list_c</a>&lt;int,-1,-7,-2,-5&gt; negatives;
 146 typedef <a href="./reverse-fold.html" class="identifier">reverse_fold</a>&lt;
 147       numbers
 148     , <a href="./list-c.html" class="identifier">list_c</a>&lt;int&gt;
 149     , <a href="./if.html" class="identifier">if_</a>&lt; <a href="./less.html" class="identifier">less</a>&lt; <a href="./placeholders.html" class="identifier">_2</a>,<a href="./int.html" class="identifier">int_</a>&lt;0&gt; &gt;, <a href="./push-front.html" class="identifier">push_front</a>&lt;<a href="./placeholders.html" class="identifier">_1</a>,<a href="./placeholders.html" class="identifier">_2</a>,&gt;, <a href="./placeholders.html" class="identifier">_1</a> &gt;
 150     &gt;::type result;
 151
 152 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./equal.html" class="identifier">equal</a>&lt; negatives,result > ));
 153 </pre>
 154 <table class="docutils footnote" frame="void" id="reverse-fold-note" rules="none">
 155 <colgroup><col class="label" /><col /></colgroup>
 156 <tbody valign="top">
 157 <tr><td class="label"><a class="fn-backref" href="#id517">[2]</a></td><td>See <tt class="literal"><span class="pre"><a href="./remove-if.html" class="identifier">remove_if</a></span></tt> for a more compact way to do this.</td></tr>
 158 </tbody>
 159 </table>
 160 </div>
 161 <div class="section" id="id518">
 162 <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
 163 <p><a class="reference internal" href="./algorithms.html">Algorithms</a>, <a class="reference internal" href="./fold.html">fold</a>, <a class="reference internal" href="./reverse-iter-fold.html">reverse_iter_fold</a>, <a class="reference internal" href="./iter-fold.html">iter_fold</a></p>
 164 <!-- Algorithms/Iteration Algorithms//reverse_iter_fold -->
 165 </div>
 166 </div>
 167
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 170 <td><div class="copyright-footer"><div class="copyright">Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams</div>
 171 Distributed under the Boost Software License, Version 1.0. (See accompanying
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