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

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   3         <title>BOOST_PP_LIST_FIRST_N</title>
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   8                 The <b>BOOST_PP_LIST_FIRST_N</b> macro expands to a <i>list</i> of the first <i>count</i> elements of a <i>list</i>.
   9         </div>
  10         <h4>Usage</h4>
  11                 <div class="code">
  12                         <b>BOOST_PP_LIST_FIRST_N</b>(<i>count</i>, <i>list</i>)
  13                 </div>
  14         <h4>Arguments</h4>
  15                 <dl>
  16                         <dt>count</dt>
  17                         <dd>
  18                                 The number of elements to extract.
  19                         </dd>
  20                         <dt>list</dt>
  21                         <dd>
  22                                 The <i>list</i> from which the elements are extracted.
  23                         </dd>
  24                 </dl>
  25         <h4>Remarks</h4>
  26                 <div>
  27                         This macro extracts <i>count</i> elements from the beginning of <i>list</i> and returns them as a <i>list</i>
  28                 </div>
  29                 <div>
  30                         Previously, this macro could not be used inside <b>BOOST_PP_WHILE</b>.&nbsp;
  31                         There is no longer any such restriction.&nbsp;
  32                         It is more efficient, however, to use <b>BOOST_PP_LIST_FIRST_N_D</b> in such a situation.
  33                 </div>
  34         <h4>See Also</h4>
  35                 <ul>
  36                         <li><a href="list_first_n_d.html">BOOST_PP_LIST_FIRST_N_D</a></li>
  37                 </ul>
  38         <h4>Requirements</h4>
  39                 <div>
  40                         <b>Header:</b> &nbsp;<a href="../headers/list/first_n.html">&lt;boost/preprocessor/list/first_n.hpp&gt;</a>
  41                 </div>
  42         <h4>Sample Code</h4>
  43 <div><pre>
  44 #include &lt;<a href="../headers/list/first_n.html">boost/preprocessor/list/first_n.hpp</a>&gt;
  45
  46 #define LIST (a, (b, (c, <a href="nil.html">BOOST_PP_NIL</a>)))
  47
  48 <a href="list_first_n.html">BOOST_PP_LIST_FIRST_N</a>(2, LIST) // expands to (a, (b, <a href="nil.html">BOOST_PP_NIL</a>))
  49 </pre></div>
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  52                 <i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
  53                 </br><i>© Copyright Paul Mensonides 2002</i>
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  55         <div style="margin-left: 0px;">
  56                 <p><small>Distributed under the Boost Software License, Version 1.0. (See
  57                 accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
  58                 copy at <a href=
  59                 "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
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