ceph/src/boost/libs/mpl/doc/refmanual/count-if.html

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   7 <title>The MPL Reference Manual: count_if</title>
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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="./querying-algorithms.html" class="navigation-link">Querying Algorithms</a> / <a href="./count-if.html" class="navigation-link">count_if</a></td>
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  14 <div class="section" id="count-if">
  15 <h1><a class="toc-backref" href="./querying-algorithms.html#id1479">count_if</a></h1>
  16 <div class="section" id="id567">
  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 Pred
  22     &gt;
  23 struct <a href="./count-if.html" class="identifier">count_if</a>
  24 {
  25     typedef <em>unspecified</em> type;
  26 };
  27 </pre>
  28 </div>
  29 <div class="section" id="id568">
  30 <h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
  31 <p>Returns the number of elements in <tt class="literal"><span class="pre">Sequence</span></tt> that satisfy the predicate <tt class="literal"><span class="pre">Pred</span></tt>.</p>
  32 </div>
  33 <div class="section" id="id569">
  34 <h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
  35 <pre class="literal-block">
  36 #include &lt;<a href="../../../../boost/mpl/count_if.hpp" class="header">boost/mpl/count_if.hpp</a>&gt;
  37 </pre>
  38 </div>
  39 <div class="section" id="id570">
  40 <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  41 <table border="1" class="docutils table">
  42 <colgroup>
  43 <col width="19%" />
  44 <col width="38%" />
  45 <col width="43%" />
  46 </colgroup>
  47 <thead valign="bottom">
  48 <tr><th class="head">Parameter</th>
  49 <th class="head">Requirement</th>
  50 <th class="head">Description</th>
  51 </tr>
  52 </thead>
  53 <tbody valign="top">
  54 <tr><td><tt class="literal"><span class="pre">Sequence</span></tt></td>
  55 <td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td>
  56 <td>A sequence to be examined.</td>
  57 </tr>
  58 <tr><td><tt class="literal"><span class="pre">Pred</span></tt></td>
  59 <td>Unary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a></td>
  60 <td>A count condition.</td>
  61 </tr>
  62 </tbody>
  63 </table>
  64 </div>
  65 <div class="section" id="id571">
  66 <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  67 <p>For any <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a> <tt class="literal"><span class="pre">s</span></tt> and unary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a> <tt class="literal"><span class="pre">pred</span></tt>:</p>
  68 <pre class="literal-block">
  69 typedef <a href="./count-if.html" class="identifier">count_if</a>&lt;s,pred&gt;::type n;
  70 </pre>
  71 <table class="docutils field-list" frame="void" rules="none">
  72 <col class="field-name" />
  73 <col class="field-body" />
  74 <tbody valign="top">
  75 <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="./integral-constant.html">Integral Constant</a>.</p>
  76 </td>
  77 </tr>
  78 <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p>
  79 <pre class="last literal-block">
  80 typedef <a href="./lambda.html" class="identifier">lambda</a>&lt;pred&gt;::type p;
  81 typedef <a href="./fold.html" class="identifier">fold</a>&lt;
  82       s
  83     , <a href="./long.html" class="identifier">long_</a>&lt;0&gt;
  84     , <a href="./if.html" class="identifier">if_</a>&lt; <a href="./apply-wrap.html" class="identifier">apply_wrap</a><tt class="literal"><span class="pre">1</span></tt>&lt;p,<a href="./placeholders.html" class="identifier">_2</a>&gt;, <a href="./next.html" class="identifier">next</a>&lt;<a href="./placeholders.html" class="identifier">_1</a>&gt;, <a href="./placeholders.html" class="identifier">_1</a> &gt;
  85     &gt;::type n;
  86 </pre>
  87 </td>
  88 </tr>
  89 </tbody>
  90 </table>
  91 </div>
  92 <div class="section" id="id572">
  93 <h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3>
  94 <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">pred</span></tt>.</p>
  95 </div>
  96 <div class="section" id="id573">
  97 <h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
  98 <pre class="literal-block">
  99 typedef <a href="./vector.html" class="identifier">vector</a>&lt;int,char,long,short,char,long,double,long&gt; types;
 100
 101 <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( (<a href="./count-if.html" class="identifier">count_if</a>&lt; types, is_float&lt;_&gt; &gt;::value), ==, 1 );
 102 <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( (<a href="./count-if.html" class="identifier">count_if</a>&lt; types, is_same&lt;_,char&gt; &gt;::value), ==, 2 );
 103 <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( (<a href="./count-if.html" class="identifier">count_if</a>&lt; types, is_same&lt;_,void&gt; &gt;::value), ==, 0 );
 104 </pre>
 105 </div>
 106 <div class="section" id="id574">
 107 <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
 108 <p><a class="reference internal" href="./querying-algorithms.html">Querying Algorithms</a>, <a class="reference internal" href="./count.html">count</a>, <a class="reference internal" href="./find.html">find</a>, <a class="reference internal" href="./find-if.html">find_if</a>, <a class="reference internal" href="./contains.html">contains</a></p>
 109 <!-- Algorithms/Querying Algorithms//lower_bound |60 -->
 110 </div>
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