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	<title>BOOST_PP_LIST_FILTER</title>
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	<div style="margin-left:  0px;">
		The <b>BOOST_PP_LIST_FILTER</b> macro filters a <i>list</i> according to a supplied criterion.
	</div>
	<h4>Usage</h4>
		<div class="code">
			<b>BOOST_PP_LIST_FILTER</b>(<i>pred</i>, <i>data</i>, <i>list</i>)
		</div>
	<h4>Arguments</h4>
		<dl>
			<dt>pred</dt>
			<dd>
				A ternary predicate of the form <i>pred</i>(<i>d</i>, <i>data</i>, <i>elem</i>).&nbsp;
				This predicate is expanded by <b>BOOST_PP_LIST_FILTER</b> for each element in <i>list</i> with the next available <b>BOOST_PP_WHILE</b> iteration,
				the auxiliary <i>data</i>, and the current element in <i>list</i>.&nbsp;
				This macro must return a integral value in the range of <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>.&nbsp;
				If this predicate expands to non-zero for a certain element, that element is included in the resulting <i>list</i>.
			</dd>
			<dt>data</dt>
			<dd>
				Auxiliary data passed to <i>pred</i>.
			</dd>
			<dt>list</dt>
			<dd>
				The <i>list</i> to be filtered.
			</dd>
		</dl>
	<h4>Remarks</h4>
		<div>
			This macro expands <i>pred</i> for each element in <i>list</i>.&nbsp;
			It builds a new <i>list</i> out of each element for which <i>pred</i> returns non-zero.
		</div>
		<div>
			Previously, this macro could not be used inside <b>BOOST_PP_WHILE</b>.&nbsp;
			There is no longer any such restriction.&nbsp;
			It is more efficient, however, to use <b>BOOST_PP_LIST_FILTER_D</b> in such a situation.
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	<h4>See Also</h4>
		<ul>
			<li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li>
			<li><a href="list_filter_d.html">BOOST_PP_LIST_FILTER_D</a></li>
		</ul>
	<h4>Requirements</h4>
		<div>
			<b>Header:</b> &nbsp;<a href="../headers/list/filter.html">&lt;boost/preprocessor/list/filter.hpp&gt;</a>
		</div>
	<h4>Sample Code</h4>
<div><pre>
#include &lt;<a href="../headers/comparison/less_equal.html">boost/preprocessor/comparison/less_equal.hpp</a>&gt;
#include &lt;<a href="../headers/list/filter.html">boost/preprocessor/list/filter.hpp</a>&gt;

#define LIST (1, (3, (2, (5, <a href="nil.html">BOOST_PP_NIL</a>))))

#define PRED(d, data, elem) <a href="less_equal.html">BOOST_PP_LESS_EQUAL</a>(elem, data)

<a href="list_filter.html">BOOST_PP_LIST_FILTER</a>(PRED, 3, LIST)
   // expands to (1, (3, (2, <a href="nil.html">BOOST_PP_NIL</a>)))
</pre></div>
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	<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>
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