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| <title>BOOST_PP_SEQ_FOLD_LEFT</title> |
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| The <b>BOOST_PP_SEQ_FOLD_LEFT</b> macro folds (or accumulates) the elements of |
| a <i>seq</i> left-to-right. |
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| <h4> |
| Usage |
| </h4> |
| <div class="code"> |
| <b>BOOST_PP_SEQ_FOLD_LEFT</b>(<i>op</i>, <i>state</i>, <i>seq</i>) |
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| <h4> |
| Arguments |
| </h4> |
| <dl> |
| <dt>op</dt> |
| <dd> |
| A ternary operation of the form <i>op</i>(<i>s</i>, <i>state</i>, <i>elem</i>). |
| This macro is called for each element in <i>seq</i>--each time returning a new <i>state</i>. |
| This operation is expanded by <b>BOOST_PP_SEQ_FOLD_LEFT</b> with the next |
| available fold step, the current <i>state</i>, and the current element. |
| </dd> |
| <dt>state</dt> |
| <dd> |
| The initial state of the fold. |
| </dd> |
| <dt>seq</dt> |
| <dd> |
| The <i>seq</i> to be folded. |
| </dd> |
| </dl> |
| <h4> |
| Remarks |
| </h4> |
| <div> |
| For the <i>seq</i>, (<i>0</i>)(<i>1</i>)(<i>2</i>), this macro expands to: |
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| <i>op</i>(<i>s</i>, <i>op</i>(<i>s</i>, <i>op</i>(<i>s</i>, <i>state</i>, <i>0</i>), |
| <i>1</i>), <i>2</i>) |
| </div> |
| </div> |
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| For maximum efficiency, <b>BOOST_PP_SEQ_FOLD_LEFT</b> can be reentered with <b>BOOST_PP_SEQ_FOLD_LEFT_<i>s</i></b>. |
| </div> |
| <h4> |
| See Also |
| </h4> |
| <ul> |
| <li> |
| <a href="seq_fold_left_s.html">BOOST_PP_SEQ_FOLD_LEFT_<i>s</i></a></li> |
| </ul> |
| <h4> |
| Requirements |
| </h4> |
| <div> |
| <b>Header:</b> <a href="../headers/seq/fold_left.html"><boost/preprocessor/seq/fold_left.hpp></a> |
| </div> |
| <h4> |
| Sample Code |
| </h4> |
| <div> |
| <pre> |
| #include <<a href="../headers/cat.html">boost/preprocessor/cat.hpp</a>> |
| #include <<a href="../headers/seq/fold_left.html">boost/preprocessor/seq/fold_left.hpp</a>> |
| |
| #define SEQ (b)(o)(o)(s)(t) |
| |
| #define OP(s, state, x) <a href="cat.html">BOOST_PP_CAT</a>(state, x) |
| |
| <a href="seq_fold_left.html">BOOST_PP_SEQ_FOLD_LEFT</a>(OP, <a href="seq_head.html">BOOST_PP_SEQ_HEAD</a>(SEQ), <a href="seq_tail.html">BOOST_PP_SEQ_TAIL</a>(SEQ)) // expands to boost |
| </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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