UNPKG

boost-react-native-bundle

Version:

Boost library as in https://sourceforge.net/projects/boost/files/boost/1.57.0/

68 lines (63 loc) 2.19 kB
<html> <head> <title>BOOST_PP_EXPAND</title> <link rel="stylesheet" type="text/css" href="../styles.css"> </head> <body> <div style="margin-left: 0px;"> The <b>BOOST_PP_EXPAND</b> macro performs a double macro-expansion on its argument. </div> <h4>Usage</h4> <div class="code"> <b>BOOST_PP_EXPAND</b>(<i>x</i>) </div> <h4>Arguments</h4> <dl> <dt>x</dt> <dd> The argument to be expanded twice. </dd> </dl> <h4>Remarks</h4> <div> This macro is useful when a delay is necessary to produce the correct semantics of a macro invocation.&nbsp; For example, when a macro expands to an argument list to another macro.&nbsp; This macro will expand the the argument list on the first pass, and then rescan to expand any more macros. </div> <h4>Requirements</h4> <div> <b>Header:</b> &nbsp;<a href="../headers/facilities/expand.html">&lt;boost/preprocessor/facilities/expand.hpp&gt;</a> </div> <h4>Sample Code</h4> <div><pre> #include &lt;<a href="../headers/control/if.html">boost/preprocessor/control/if.hpp</a>&gt; #include &lt;<a href="../headers/facilities/expand.html">boost/preprocessor/facilities/expand.hpp</a>&gt; #define MACRO(a, b, c) (a)(b)(c) #define ARGS() (1, 2, 3) <a href="expand.html">BOOST_PP_EXPAND</a>(MACRO ARGS()) // expands to (1)(2)(3) #define SAMPLE(n) \ <a href="expand.html">BOOST_PP_EXPAND</a>( \ MACRO \ <a href="if.html">BOOST_PP_IF</a>( \ n, \ (x, y, z), \ (a, b, c) \ ) \ ) \ /**/ SAMPLE(0) // expands to (a)(b)(c) SAMPLE(1) // expands to (x)(y)(z) </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> </body> </html>