ceph/src/boost/libs/mpl/doc/refmanual/reverse-iter-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="./reverse-fold.html" class="navigation-link">Prev</a>&nbsp;<a href="./accumulate.html" class="navigation-link">Next</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./reverse-fold.html" class="navigation-link">Back</a>&nbsp;<a href="./accumulate.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-iter-fold.html" class="navigation-link">reverse_iter_fold</a></td>
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  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">
  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-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
  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 each iterator 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>)
  36 in reverse order. If <tt class="literal"><span class="pre">ForwardOp</span></tt> is provided, then it's applied on forward
  37 traversal 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 &lt;<a href="../../../../boost/mpl/reverse_iter_fold.hpp" class="header">boost/mpl/reverse_iter_fold.hpp</a>&gt;
  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
  72 traversal.</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
  77 traversal.</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>,
  85 and arbitrary type <tt class="literal"><span class="pre">state</span></tt>:</p>
  86 <pre class="literal-block">
  87 typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>&lt; s,state,backward_op &gt;::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">
  98 typedef <a href="./begin.html" class="identifier">begin</a>&lt;s&gt;::type i<sub>1</sub>;
  99 typedef <a href="./next.html" class="identifier">next</a>&lt;i<sub>1</sub>&gt;::type i<sub>2</sub>;
 100 <em>...</em>
 101 typedef <a href="./next.html" class="identifier">next</a>&lt;i<sub>n</sub>&gt;::type last;
 102 typedef <a href="./apply.html" class="identifier">apply</a>&lt;backward_op,state,i<sub>n</sub>&gt;::type state<sub>n</sub>;
 103 typedef <a href="./apply.html" class="identifier">apply</a>&lt;backward_op,state<sub>n</sub>,i<sub>n-1</sub>&gt;::type state<sub>n-1</sub>;
 104 <em>...</em>
 105 typedef <a href="./apply.html" class="identifier">apply</a>&lt;backward_op,state<sub>2</sub>,i<sub>1</sub>&gt;::type state<sub>1</sub>;
 106 typedef 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>&lt;s&gt;::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>&lt;s&gt;::type</span></tt>; equivalent
 109 to <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>&lt;s&gt;::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">
 116 typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>&lt; s,state,backward_op,forward_op &gt;::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">
 127 typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>&lt;
 128       Sequence
 129     , <a href="./iter-fold.html" class="identifier">iter_fold</a>&lt;s,state,forward_op&gt;::type
 130     , backward_op
 131     &gt;::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>&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>
 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">
 146 typedef <a href="./vector-c.html" class="identifier">vector_c</a>&lt;int,5,-1,0,-7,-2,0,-5,4&gt; numbers;
 147 typedef <a href="./list-c.html" class="identifier">list_c</a>&lt;int,-1,-7,-2,-5&gt; negatives;
 148 typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>&lt;
 149       numbers
 150     , <a href="./list.html" class="identifier">list</a>&lt;&gt;
 151     , <a href="./if.html" class="identifier">if_</a>&lt; <a href="./less.html" class="identifier">less</a>&lt; <a href="./deref.html" class="identifier">deref</a>&lt;<a href="./placeholders.html" class="identifier">_2</a>&gt;,<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;
 152     &gt;::type iters;
 153
 154 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./equal.html" class="identifier">equal</a>&lt;
 155       negatives
 156     , <a href="./transform-view.html" class="identifier">transform_view</a>&lt; iters,<a href="./deref.html" class="identifier">deref</a>&lt;<a href="./placeholders.html" class="identifier">_1</a>&gt; >
 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
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