ceph/src/boost/libs/preprocessor/doc/ref/list_at_d.html

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   2 <head>
   3         <title>BOOST_PP_LIST_AT_D</title>
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   8                 The <b>BOOST_PP_LIST_AT_D</b> macro extracts an element in a <i>list</i>.&nbsp;
   9                 It reenters <b>BOOST_PP_WHILE</b> with maximum efficiency.
  10         </div>
  11         <h4>Usage</h4>
  12                 <div class="code">
  13                         <b>BOOST_PP_LIST_AT_D</b>(<i>d</i>, <i>list</i>, <i>index</i>)
  14                 </div>
  15         <h4>Arguments</h4>
  16                 <dl>
  17                         <dt>d</dt>
  18                         <dd>
  19                                 The next available <b>BOOST_PP_WHILE</b> iteration.
  20                         </dd>
  21                         <dt>list</dt>
  22                         <dd>
  23                                 The <i>list</i> from which a element is to be extracted.&nbsp;
  24                                 This <i>list</i> must have at least <i>index</i> + <i>1</i> elements.
  25                         </dd>
  26                         <dt>index</dt>
  27                         <dd>
  28                                 The zero-based position in the <i>list</i> of the element to be extracted.
  29                         </dd>
  30                 </dl>
  31         <h4>See Also</h4>
  32                 <ul>
  33                         <li><a href="list_at.html">BOOST_PP_LIST_AT</a></li>
  34                 </ul>
  35         <h4>Requirements</h4>
  36                 <div>
  37                         <b>Header:</b> &nbsp;<a href="../headers/list/at.html">&lt;boost/preprocessor/list/at.hpp&gt;</a>
  38                 </div>
  39         <h4>Sample Code</h4>
  40 <div><pre>
  41 #include &lt;<a href="../headers/control/while.html">boost/preprocessor/control/while.hpp</a>&gt;
  42 #include &lt;<a href="../headers/list/at.html">boost/preprocessor/list/at.hpp</a>&gt;
  43
  44 #define LIST (7, (2, (0, (1, <a href="nil.html">BOOST_PP_NIL</a>))))
  45
  46 #define PRED(d, state) <a href="list_at_d.html">BOOST_PP_LIST_AT_D</a>(d, state, 0)
  47 #define OP(d, state) <a href="list_rest.html">BOOST_PP_LIST_REST</a>(state)
  48
  49 <a href="while.html">BOOST_PP_WHILE</a>(PRED, OP, LIST) // expands to (0, (1, <a href="nil.html">BOOST_PP_NIL</a>))
  50 </pre></div>
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  53                 <i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
  54                 </br><i>© Copyright Paul Mensonides 2002</i>
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  56         <div style="margin-left: 0px;">
  57                 <p><small>Distributed under the Boost Software License, Version 1.0. (See
  58                 accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
  59                 copy at <a href=
  60                 "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
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