projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | <html> |
| 2 | <head> | |
| 3 | <title>BOOST_PP_LIST_FIRST_N_D</title> | |
| 4 | <link rel="stylesheet" type="text/css" href="../styles.css"> | |
| 5 | </head> | |
| 6 | <body> | |
| 7 | <div style="margin-left: 0px;"> | |
| 8 | The <b>BOOST_PP_LIST_FIRST_N_D</b> macro expands to a <i>list</i> of the first <i>count</i> elements of a <i>list</i>. | |
| 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_FIRST_N_D</b>(<i>d</i>, <i>count</i>, <i>list</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>count</dt> | |
| 22 | <dd> | |
| 23 | The number of elements to extract. | |
| 24 | </dd> | |
| 25 | <dt>list</dt> | |
| 26 | <dd> | |
| 27 | The <i>list</i> from which the elements are extracted. | |
| 28 | </dd> | |
| 29 | </dl> | |
| 30 | <h4>Remarks</h4> | |
| 31 | <div> | |
| 32 | This macro extracts <i>count</i> elements from the beginning of <i>list</i> and returns them as a <i>list</i> | |
| 33 | </div> | |
| 34 | <h4>See Also</h4> | |
| 35 | <ul> | |
| 36 | <li><a href="list_first_n.html">BOOST_PP_LIST_FIRST_N</a></li> | |
| 37 | </ul> | |
| 38 | <h4>Requirements</h4> | |
| 39 | <div> | |
| 40 | <b>Header:</b> <a href="../headers/list/first_n.html"><boost/preprocessor/list/first_n.hpp></a> | |
| 41 | </div> | |
| 42 | <h4>Sample Code</h4> | |
| 43 | <div><pre> | |
| 44 | #include <<a href="../headers/list/first_n.html">boost/preprocessor/list/first_n.hpp</a>> | |
| 45 | #include <<a href="../headers/list/fold_left.html">boost/preprocessor/list/fold_right.hpp</a>> | |
| 46 | ||
| 47 | #define L1 (a, (b, (c, (d, <a href="nil.html">BOOST_PP_NIL</a>)))) | |
| 48 | #define L2 (L1, (L1, (L1, <a href="nil.html">BOOST_PP_NIL</a>))) | |
| 49 | ||
| 50 | #define OP(d, state, x) (<a href="list_first_n_d.html">BOOST_PP_LIST_FIRST_N_D</a>(d, 2, x), state) | |
| 51 | ||
| 52 | <a href="list_fold_right.html">BOOST_PP_LIST_FOLD_RIGHT</a>(OP, <a href="nil.html">BOOST_PP_NIL</a>, L2) | |
| 53 | /* | |
| 54 | expands to... | |
| 55 | ((a, (b, <a href="nil.html">BOOST_PP_NIL</a>)), ((a, (b, <a href="nil.html">BOOST_PP_NIL</a>)), | |
| 56 | ((a, (b, <a href="nil.html">BOOST_PP_NIL</a>)) , <a href="nil.html">BOOST_PP_NIL</a> ))) | |
| 57 | */ | |
| 58 | </pre></div> | |
| 59 | <hr size="1"> | |
| 60 | <div style="margin-left: 0px;"> | |
| 61 |