forked from boostorg/preprocessor
55 lines
1.9 KiB
HTML
55 lines
1.9 KiB
HTML
<html>
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<head>
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<title>BOOST_PP_APPLY</title>
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<link rel="stylesheet" type="text/css" href="../styles.css">
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<script language="javascript" type="text/javascript" src="../scripts.js"></script>
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</head>
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<body onload="init('sample');">
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<div style="margin-left: 0px;">
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The <b>BOOST_PP_APPLY</b> macro abstracts the difference between an argument and nothing.
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</div>
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<h4>Usage</h4>
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<div class="code">
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<b>BOOST_PP_APPLY</b>(<i>x</i>)
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</div>
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<h4>Arguments</h4>
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<dl>
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<dt>x</dt>
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<dd>
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The abstracted argument.
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This argument must be either <b>BOOST_PP_NIL</b> or a <i>tuple</i> with one element--such as <i>(arg)</i> or <i>((a, b))</i>.
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</dd>
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</dl>
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<h4>Remarks</h4>
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<div>
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If <i>x</i> is <b>BOOST_PP_NIL</b>, this macro expands to nothing.
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If <i>x</i> is a one element <i>tuple</i>, it expands to the contents of that <i>tuple</i>.
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</div>
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<h4>See Also</h4>
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<ul>
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<li><a href="nil.html">BOOST_PP_NIL</a></li>
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</ul>
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<h4>Requirements</h4>
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<div>
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<b>Header:</b> <a href="../headers/facilities/apply.hpp.html"><boost/preprocessor/facilities/apply.hpp></a>
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</div>
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<h4><a class="local" onclick="toggle('sample');" onmouseover="change(this);" onmouseout="revert(this);">Sample Code</a></h4>
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<div id="sample"><pre>
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#include <boost/preprocessor/facilities/apply.hpp>
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#include <boost/preprocessor/tuple/elem.hpp>
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#define CV(i) /* .......................................... */ \
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BOOST_PP_APPLY( \
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BOOST_PP_TUPLE_ELEM( \
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4, i, \
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(BOOST_PP_NIL, (const), (volatile), (const volatile)) \
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) \
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) \
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/**/
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CV(0) // expands to nothing
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CV(1) // expands to const
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<pre></div>
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</body>
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</html>
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