projects / ceph.git / blame
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|---|---|---|
| 7c673cae FG |
1 | <html> |
| 2 | <head> | |
| 3 | <title>BOOST_PP_LIST_FOR_EACH</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_FOR_EACH</b> macro repeats a macro for each element in a <i>list</i>. | |
| 9 | </div> | |
| 10 | <h4>Usage</h4> | |
| 11 | <div class="code"> | |
| 12 | <b>BOOST_PP_LIST_FOR_EACH</b>(<i>macro</i>, <i>data</i>, <i>list</i>) | |
| 13 | </div> | |
| 14 | <h4>Arguments</h4> | |
| 15 | <dl> | |
| 16 | <dt>macro</dt> | |
| 17 | <dd> | |
| 18 | A ternary macro of the form <i>macro</i>(<i>r</i>, <i>data</i>, <i>elem</i>). | |
| 19 | This macro is expanded by <b>BOOST_PP_LIST_FOR_EACH</b> with each element in <i>list</i>. | |
| 20 | It is expanded with the next available <b>BOOST_PP_FOR</b> repetition, the auxiliary <i>data</i>, and the current element. | |
| 21 | </dd> | |
| 22 | <dt>data</dt> | |
| 23 | <dd> | |
| 24 | Auxiliary data passed to <i>macro</i>. | |
| 25 | </dd> | |
| 26 | <dt>list</dt> | |
| 27 | <dd> | |
| 28 | The <i>list</i> for which <i>macro</i> will be invoked on each element. | |
| 29 | </dd> | |
| 30 | </dl> | |
| 31 | <h4>Remarks</h4> | |
| 32 | <div> | |
| 33 | This macro is a repetition construct. | |
| 34 | If <i>list</i> is (<i>a</i>, (<i>b</i>, (<i>c</i>, <b>BOOST_PP_NIL</b>))), it expands to the sequence: | |
| 35 | <div> | |
| 36 | <i>macro</i>(<i>r</i>, <i>data</i>, <i>a</i>) <i>macro</i>(<i>r</i>, <i>data</i>, <i>b</i>) <i>macro</i>(<i>r</i>, <i>data</i>, <i>c</i>) | |
| 37 | </div> | |
| 38 | </div> | |
| 39 | <div> | |
| 40 | Previously, this macro could not be used inside <b>BOOST_PP_FOR</b>. | |
| 41 | There is no longer any such restriction. | |
| 42 | It is more efficient, however, to use <b>BOOST_PP_LIST_FOR_EACH_R</b> in such a situation. | |
| 43 | </div> | |
| 44 | <h4>See Also</h4> | |
| 45 | <ul> | |
| 46 | <li><a href="list_for_each_r.html">BOOST_PP_LIST_FOR_EACH_R</a></li> | |
| 47 | </ul> | |
| 48 | <h4>Requirements</h4> | |
| 49 | <div> | |
| 50 | <b>Header:</b> <a href="../headers/list/for_each.html"><boost/preprocessor/list/for_each.hpp></a> | |
| 51 | </div> | |
| 52 | <h4>Sample Code</h4> | |
| 53 | <div><pre> | |
| 54 | #include <<a href="../headers/cat.html">boost/preprocessor/cat.hpp</a>> | |
| 55 | #include <<a href="../headers/list/for_each.html">boost/preprocessor/list/for_each.hpp</a>> | |
| 56 | ||
| 57 | #define LIST (w, (x, (y, (z, <a href="nil.html">BOOST_PP_NIL</a>)))) | |
| 58 | ||
| 59 | #define MACRO(r, data, elem) <a href="cat.html">BOOST_PP_CAT</a>(elem, data) | |
| 60 | ||
| 61 | <a href="list_for_each.html">BOOST_PP_LIST_FOR_EACH</a>(MACRO, _, LIST) // expands to w_ x_ y_ z_ | |
| 62 | </pre></div> | |
| 63 | <hr size="1"> | |
| 64 | <div style="margin-left: 0px;"> | |
| 65 |