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| <title>BOOST_PP_SEQ_FILTER</title> |
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| The <b>BOOST_PP_SEQ_FILTER</b> macro filters a <i>seq</i> according to a |
| supplied criterion. |
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| <h4> |
| Usage |
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| <div class="code"> |
| <b>BOOST_PP_SEQ_FILTER</b>(<i>pred</i>, <i>data</i>, <i>seq</i>) |
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| <h4> |
| Arguments |
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| <dl> |
| <dt>pred</dt> |
| <dd> |
| A ternary predicate of the form <i>pred</i>(<i>s</i>, <i>data</i>, <i>elem</i>). |
| This predicate is expanded by <b>BOOST_PP_SEQ_FILTER</b> for each element in <i>seq</i> |
| with the next available <b>BOOST_PP_SEQ_FOLD_LEFT</b> fold step, the auxiliary <i>data</i>, |
| and the current element in <i>seq</i>. This macro must return a integral |
| value in the range of <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>. If this |
| predicate expands to non-zero for a certain element, that element is included |
| in the resulting <i>seq</i>. |
| </dd> |
| <dt>data</dt> |
| <dd> |
| Auxiliary data passed to <i>pred</i>. |
| </dd> |
| <dt>seq</dt> |
| <dd> |
| The <i>seq</i> to be filtered. |
| </dd> |
| </dl> |
| <h4> |
| Remarks |
| </h4> |
| <div> |
| This macro expands <i>pred</i> for each element in <i>seq</i>. It builds |
| a new <i>seq</i> out of each element for which <i>pred</i> returns non-zero. |
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| For maximum efficiency, use <b>BOOST_PP_SEQ_FILTER_S</b>. |
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| <h4> |
| See Also |
| </h4> |
| <ul> |
| <li> |
| <a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li> |
| <li> |
| <a href="seq_filter_s.html">BOOST_PP_SEQ_FILTER_S</a></li> |
| </ul> |
| <h4> |
| Requirements |
| </h4> |
| <div> |
| <b>Header:</b> <a href="../headers/seq/filter.html"><boost/preprocessor/seq/filter.hpp></a> |
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| <h4> |
| Sample Code |
| </h4> |
| <div> |
| <pre> |
| #include <<a href="../headers/comparison/less_equal.html">boost/preprocessor/comparison/less_equal.hpp</a>> |
| #include <<a href="../headers/seq/filter.html">boost/preprocessor/seq/filter.hpp</a>> |
| |
| #define SEQ (1)(3)(2)(5) |
| |
| #define PRED(s, data, elem) <a href="less_equal.html">BOOST_PP_LESS_EQUAL</a>(elem, data) |
| |
| <a href="seq_filter.html">BOOST_PP_SEQ_FILTER</a>(PRED, 3, SEQ) |
| // expands to (1)(3)(2) |
| </pre> |
| </div> |
| <hr size="1"> |
| <div style="margin-left: 0px;"> |
| <i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i> |
| </br><i>© Copyright Paul Mensonides 2002</i> |
| </div> |
| <div style="margin-left: 0px;"> |
| <p><small>Distributed under the Boost Software License, Version 1.0. (See |
| accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or |
| copy at <a href= |
| "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p> |
| </div> |
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