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

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  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="./iter-fold.html" class="navigation-link">iter_fold</a></td>
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  14 <div class="section" id="iter-fold">
  15 <h1><a class="toc-backref" href="./iteration-algorithms.html#id1470">iter_fold</a></h1>
  16 <div class="section" id="id501">
  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 ForwardOp
  23     &gt;
  24 struct <a href="./iter-fold.html" class="identifier">iter_fold</a>
  25 {
  26     typedef <em>unspecified</em> type;
  27 };
  28 </pre>
  29 </div>
  30 <div class="section" id="id502">
  31 <h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
  32 <p>Returns the result of the successive application of binary <tt class="literal"><span class="pre">ForwardOp</span></tt> to the result
  33 of the previous <tt class="literal"><span class="pre">ForwardOp</span></tt> invocation (<tt class="literal"><span class="pre">State</span></tt> if it's the first call) and each
  34 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>) in order.</p>
  35 </div>
  36 <div class="section" id="id503">
  37 <h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
  38 <pre class="literal-block">
  39 #include &lt;<a href="../../../../boost/mpl/iter_fold.hpp" class="header">boost/mpl/iter_fold.hpp</a>&gt;
  40 </pre>
  41 </div>
  42 <div class="section" id="id504">
  43 <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  44 <table border="1" class="docutils table">
  45 <colgroup>
  46 <col width="15%" />
  47 <col width="32%" />
  48 <col width="53%" />
  49 </colgroup>
  50 <thead valign="bottom">
  51 <tr><th class="head">Parameter</th>
  52 <th class="head">Requirement</th>
  53 <th class="head">Description</th>
  54 </tr>
  55 </thead>
  56 <tbody valign="top">
  57 <tr><td><tt class="literal"><span class="pre">Sequence</span></tt></td>
  58 <td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td>
  59 <td>A sequence to iterate.</td>
  60 </tr>
  61 <tr><td><tt class="literal"><span class="pre">State</span></tt></td>
  62 <td>Any type</td>
  63 <td>The initial state for the first <tt class="literal"><span class="pre">ForwardOp</span></tt>
  64 application.</td>
  65 </tr>
  66 <tr><td><tt class="literal"><span class="pre">ForwardOp</span></tt></td>
  67 <td>Binary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a></td>
  68 <td>The operation to be executed on forward
  69 traversal.</td>
  70 </tr>
  71 </tbody>
  72 </table>
  73 </div>
  74 <div class="section" id="id505">
  75 <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  76 <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">op</span></tt>, and an
  77 arbitrary type <tt class="literal"><span class="pre">state</span></tt>:</p>
  78 <pre class="literal-block">
  79 typedef <a href="./iter-fold.html" class="identifier">iter_fold</a>&lt;s,state,op&gt;::type t;
  80 </pre>
  81 <table class="docutils field-list" frame="void" rules="none">
  82 <col class="field-name" />
  83 <col class="field-body" />
  84 <tbody valign="top">
  85 <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A type.</p>
  86 </td>
  87 </tr>
  88 <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p>
  89 <pre class="literal-block">
  90 typedef <a href="./begin.html" class="identifier">begin</a>&lt;s&gt;::type i<sub>1</sub>;
  91 typedef <a href="./apply.html" class="identifier">apply</a>&lt;op,state,i<sub>1</sub>&gt;::type state<sub>1</sub>;
  92 typedef <a href="./next.html" class="identifier">next</a>&lt;i<sub>1</sub>&gt;::type i<sub>2</sub>;
  93 typedef <a href="./apply.html" class="identifier">apply</a>&lt;op,state<sub>1</sub>,i<sub>2</sub>&gt;::type state<sub>2</sub>;
  94 <em>...</em>
  95 typedef <a href="./apply.html" class="identifier">apply</a>&lt;op,state<sub>n-1</sub>,i<sub>n</sub>&gt;::type state<sub>n</sub>;
  96 typedef <a href="./next.html" class="identifier">next</a>&lt;i<sub>n</sub>&gt;::type last;
  97 typedef state<sub>n</sub> t;
  98 </pre>
  99 <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
 100 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>
 101 </td>
 102 </tr>
 103 </tbody>
 104 </table>
 105 </div>
 106 <div class="section" id="id506">
 107 <h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3>
 108 <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">op</span></tt>.</p>
 109 </div>
 110 <div class="section" id="id507">
 111 <h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
 112 <pre class="literal-block">
 113 typedef <a href="./vector-c.html" class="identifier">vector_c</a>&lt;int,5,-1,0,7,2,0,-5,4&gt; numbers;
 114 typedef <a href="./iter-fold.html" class="identifier">iter_fold</a>&lt;
 115       numbers
 116     , <a href="./begin.html" class="identifier">begin</a>&lt;numbers&gt;::type
 117     , <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">_1</a>&gt;, <a href="./deref.html" class="identifier">deref</a>&lt;<a href="./placeholders.html" class="identifier">_2</a>&gt; &gt;,<a href="./placeholders.html" class="identifier">_2</a>,<a href="./placeholders.html" class="identifier">_1</a> &gt;
 118     &gt;::type max_element_iter;
 119
 120 <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( <a href="./deref.html" class="identifier">deref</a>&lt;max_element_iter&gt;::type::value, ==, 7 );
 121 </pre>
 122 </div>
 123 <div class="section" id="id508">
 124 <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
 125 <p><a class="reference internal" href="./algorithms.html">Algorithms</a>, <a class="reference internal" href="./reverse-iter-fold.html">reverse_iter_fold</a>, <a class="reference internal" href="./fold.html">fold</a>, <a class="reference internal" href="./reverse-fold.html">reverse_fold</a>, <a class="reference internal" href="./copy.html">copy</a></p>
 126 <!-- Algorithms/Iteration Algorithms//reverse_fold -->
 127 </div>
 128 </div>
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