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- <html>
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- <title>BOOST_PP_FOR</title>
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- <div style="margin-left: 0px;">
- The <b>BOOST_PP_FOR</b> macro represents a generalized horizontal repetition construct.
- </div>
- <h4>Usage</h4>
- <div class="code">
- <b>BOOST_PP_FOR</b>(<i>state</i>, <i>pred</i>, <i>op</i>, <i>macro</i>)
- </div>
- <h4>Arguments</h4>
- <dl>
- <dt>state</dt>
- <dd>
- The initial state.
- </dd>
- <dt>pred</dt>
- <dd>
- A binary predicate of the form <i>pred</i>(<i>r</i>, <i>state</i>).
- This macro must expand to an integer in the range of <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>.
- <b>BOOST_PP_FOR</b> repeatedly expands <i>macro</i> while this predicate returns non-zero.
- This macro is called with the next available <b>BOOST_PP_FOR</b> repetition and the current <i>state</i>.
- </dd>
- <dt>op</dt>
- <dd>
- A binary operation of the form <i>op</i>(<i>r</i>, <i>state</i>).
- This operation is expanded by <b>BOOST_PP_FOR</b> with the next available <b>BOOST_PP_FOR</b> repetition and the current <i>state</i>.
- This macro is repeatedly applied to the <i>state</i>, each time producing a new <i>state</i>, until <i>pred</i> returns <i>0</i>.
- </dd>
- <dt>macro</dt>
- <dd>
- A binary macro of the form <i>macro</i>(<i>r</i>, <i>state</i>).
- This macro is expanded by <b>BOOST_PP_FOR</b> with the next available <b>BOOST_PP_FOR</b> repetition and the current <i>state</i>.
- This macro is is repeated by <b>BOOST_PP_FOR</b> until <i>pred</i> returns <i>0</i>.
- </dd>
- </dl>
- <h4>Remarks</h4>
- <div>
- This macro expands to the sequence:
- <div>
- <i>macro</i>(<i>r</i>, <i>state</i>) <i>macro</i>(<i>r</i>, <i>op</i>(<i>r</i>, <i>state</i>)) ... <i>macro</i>(<i>r</i>, <i>op</i>(<i>r</i>, ... <i>op</i>(<i>r</i>, <i>state</i>) ... ))
- </div>
- </div>
- <div>
- The <i>r</i> value that is passed to <i>pred</i>, <i>op</i>, and <i>macro</i> represents the next available <b>BOOST_PP_FOR</b> repetition.
- Other macros that have <b>_R</b> suffix variants internally use <b>BOOST_PP_FOR</b>--for example, <b>BOOST_PP_LIST_FOR_EACH</b> and <b>BOOST_PP_LIST_FOR_EACH_R</b>.
- Using these <b>_R</b> versions is not strictly necessary, but passing the <i>r</i> value (that is passed to <i>pred</i>, <i>op</i>, and <i>macro</i>) to these macros allows them to reenter <b>BOOST_PP_FOR</b> with maximum efficiency.
- </div>
- <div>
- To directly use this <i>r</i> value, rather than simply passing it to another macro, see <b>BOOST_PP_FOR_<i>r</i></b>.
- </div>
- <div>
- Previously, this macro could not be used recursively inside <b>BOOST_PP_FOR</b>.
- This limitation no longer exists, as the library can automatically detect the next available <b>BOOST_PP_FOR</b> repetition.
- </div>
- <h4>See Also</h4>
- <ul>
- <li><a href="for_r.html">BOOST_PP_FOR_<i>r</i></a></li>
- <li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li>
- </ul>
- <h4>Requirements</h4>
- <div>
- <b>Header:</b> <a href="../headers/repetition/for.html"><boost/preprocessor/repetition/for.hpp></a>
- </div>
- <h4>Sample Code</h4>
- <div><pre>
- #include <<a href="../headers/arithmetic/inc.html">boost/preprocessor/arithmetic/inc.hpp</a>>
- #include <<a href="../headers/comparison/not_equal.html">boost/preprocessor/comparison/not_equal.hpp</a>>
- #include <<a href="../headers/repetition/for.html">boost/preprocessor/repetition/for.hpp</a>>
- #include <<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>>
- #define PRED(r, state) \
- <a href="not_equal.html">BOOST_PP_NOT_EQUAL</a>( \
- <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 0, state), \
- <a href="inc.html">BOOST_PP_INC</a>(<a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 1, state)) \
- ) \
- /**/
- #define OP(r, state) \
- ( \
- <a href="inc.html">BOOST_PP_INC</a>(<a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 0, state)), \
- <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 1, state) \
- ) \
- /**/
- #define MACRO(r, state) <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 0, state)
- <a href="for.html">BOOST_PP_FOR</a>((5, 10), PRED, OP, MACRO) // expands to 5 6 7 8 9 10
- </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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