ceph/src/boost/libs/mpl/doc/refmanual/at-c.html

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   7 <title>The MPL Reference Manual: at_c</title>
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  12 <td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./sequences.html" class="navigation-link">Sequences</a> / <a href="./intrinsic-metafunctions.html" class="navigation-link">Intrinsic Metafunctions</a> / <a href="./at-c.html" class="navigation-link">at_c</a></td>
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  14 <div class="section" id="at-c">
  15 <h1><a class="toc-backref" href="./intrinsic-metafunctions.html#id1426">at_c</a></h1>
  16 <div class="section" id="id185">
  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     , long n
  22     &gt;
  23 struct <a href="./at-c.html" class="identifier">at_c</a>
  24 {
  25     typedef <em>unspecified</em> type;
  26 };
  27 </pre>
  28 </div>
  29 <div class="section" id="id186">
  30 <h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
  31 <p>Returns a type identical to the <tt class="literal"><span class="pre">n</span></tt>th element from the beginning of
  32 the sequence. <tt class="literal"><span class="pre"><a href="./at-c.html" class="identifier">at_c</a>&lt;Sequence,n&gt;::type</span></tt> is a shorcut notation for
  33 <tt class="literal"><span class="pre"><a href="./at.html" class="identifier">at</a>&lt;</span> <span class="pre">Sequence,</span> <span class="pre"><a href="./long.html" class="identifier">long_</a>&lt;n&gt;</span> <span class="pre">&gt;::type</span></tt>.</p>
  34 </div>
  35 <div class="section" id="id187">
  36 <h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
  37 <pre class="literal-block">
  38 #include &lt;<a href="../../../../boost/mpl/at.hpp" class="header">boost/mpl/at.hpp</a>&gt;
  39 </pre>
  40 </div>
  41 <div class="section" id="id188">
  42 <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  43 <table border="1" class="docutils table">
  44 <colgroup>
  45 <col width="15%" />
  46 <col width="36%" />
  47 <col width="48%" />
  48 </colgroup>
  49 <thead valign="bottom">
  50 <tr><th class="head">Parameter</th>
  51 <th class="head">Requirement</th>
  52 <th class="head">Description</th>
  53 </tr>
  54 </thead>
  55 <tbody valign="top">
  56 <tr><td><tt class="literal"><span class="pre">Sequence</span></tt></td>
  57 <td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td>
  58 <td>A sequence to be examined.</td>
  59 </tr>
  60 <tr><td><tt class="literal"><span class="pre">n</span></tt></td>
  61 <td>A compile-time integral constant</td>
  62 <td>An offset from the beginning of the sequence
  63 specifying the element to be retrieved.</td>
  64 </tr>
  65 </tbody>
  66 </table>
  67 </div>
  68 <div class="section" id="id189">
  69 <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  70 <pre class="literal-block">
  71 typedef <a href="./at-c.html" class="identifier">at_c</a>&lt;Sequence,n&gt;::type t;
  72 </pre>
  73 <table class="docutils field-list" frame="void" rules="none">
  74 <col class="field-name" />
  75 <col class="field-body" />
  76 <tbody valign="top">
  77 <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A type</p>
  78 </td>
  79 </tr>
  80 <tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first"><tt class="literal"><span class="pre">0</span> <span class="pre">&lt;=</span> <span class="pre">n</span> <span class="pre">&lt;</span> <span class="pre"><a href="./size.html" class="identifier">size</a>&lt;Sequence&gt;::value</span></tt></p>
  81 </td>
  82 </tr>
  83 <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p>
  84 <pre class="last literal-block">
  85 typedef <a href="./at.html" class="identifier">at</a>&lt; Sequence, <a href="./long.html" class="identifier">long_</a>&lt;n&gt; &gt;::type t;
  86 </pre>
  87 </td>
  88 </tr>
  89 </tbody>
  90 </table>
  91 </div>
  92 <div class="section" id="id190">
  93 <h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3>
  94 <table border="1" class="docutils table">
  95 <colgroup>
  96 <col width="47%" />
  97 <col width="53%" />
  98 </colgroup>
  99 <thead valign="bottom">
 100 <tr><th class="head">Sequence archetype</th>
 101 <th class="head">Complexity</th>
 102 </tr>
 103 </thead>
 104 <tbody valign="top">
 105 <tr><td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td>
 106 <td>Linear.</td>
 107 </tr>
 108 <tr><td><a class="reference internal" href="./random-access-sequence.html">Random Access Sequence</a></td>
 109 <td>Amortized constant time.</td>
 110 </tr>
 111 </tbody>
 112 </table>
 113 </div>
 114 <div class="section" id="id191">
 115 <h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
 116 <pre class="literal-block">
 117 typedef <a href="./range-c.html" class="identifier">range_c</a>&lt;long,10,50&gt; range;
 118 <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( (<a href="./at-c.html" class="identifier">at_c</a>&lt; range,0 &gt;::type::value), ==, 10 );
 119 <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( (<a href="./at-c.html" class="identifier">at_c</a>&lt; range,10 &gt;::type::value), ==, 20 );
 120 <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( (<a href="./at-c.html" class="identifier">at_c</a>&lt; range,40 &gt;::type::value), ==, 50 );
 121 </pre>
 122 </div>
 123 <div class="section" id="id192">
 124 <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
 125 <p><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a>, <a class="reference internal" href="./random-access-sequence.html">Random Access Sequence</a>, <a class="reference internal" href="./at.html">at</a>, <a class="reference internal" href="./front.html">front</a>, <a class="reference internal" href="./back.html">back</a></p>
 126 <!-- Sequences/Intrinsic Metafunctions//back -->
 127 </div>
 128 </div>
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