boost/boost/preprocessor/list/filter.hpp

   1 #ifndef BOOST_PREPROCESSOR_LIST_FILTER_HPP
   2 #define BOOST_PREPROCESSOR_LIST_FILTER_HPP
   3
   4 /* Copyright (C) 2001
   5  * Housemarque Oy
   6  * http://www.housemarque.com
   7  *
   8  * Permission to copy, use, modify, sell and distribute this software is
   9  * granted provided this copyright notice appears in all copies. This
  10  * software is provided "as is" without express or implied warranty, and
  11  * with no claim as to its suitability for any purpose.
  12  *
  13  * See http://www.boost.org for most recent version.
  14  */
  15
  16 #include <boost/preprocessor/list/fold_right.hpp>
  17
  18 /** <p>Expands to a list containing all the elements <code>X</code> of the list
  19 for which <code>PRED(D,DATA,X)</code> is true.</p>
  20
  21 <p>For example,</p>
  22
  23 <pre>
  24 BOOST_PP_LIST_FILTER(BOOST_PP_NOT_EQUAL_D,2,BOOST_PP_TUPLE_TO_LIST(3,(1,2,3)))
  25 </pre>
  26
  27 <p>expands to the same as:</p>
  28
  29 <pre>
  30 BOOST_PP_TUPLE_TO_LIST(2,(1,3))
  31 </pre>
  32
  33 <h3>Test</h3>
  34 <ul>
  35   <li><a href="../../test/list_test.cpp">list_test.cpp</a></li>
  36 </ul>
  37 */
  38 #define BOOST_PP_LIST_FILTER(PRED,DATA,LIST) BOOST_PP_LIST_FILTER_D(0,PRED,DATA,LIST)
  39
  40 /** <p>Can be used inside BOOST_PP_WHILE() (see for an explanation of the D parameter).</p> */
  41 #define BOOST_PP_LIST_FILTER_D(D,PRED,DATA,LIST) BOOST_PP_TUPLE_ELEM(3,2,BOOST_PP_LIST_FOLD_RIGHT_D(D,BOOST_PP_LIST_FILTER_F,LIST,(PRED,DATA,(_,_,0))))
  42
  43 #define BOOST_PP_LIST_FILTER_F(D,X,PDR) (BOOST_PP_TUPLE_ELEM(3,0,PDR),BOOST_PP_TUPLE_ELEM(3,1,PDR),BOOST_PP_IF(BOOST_PP_TUPLE_ELEM(3,0,PDR)(D,BOOST_PP_TUPLE_ELEM(3,1,PDR),X),BOOST_PP_LIST_CONS,BOOST_PP_IF1)(X,BOOST_PP_TUPLE_ELEM(3,2,PDR)))
  44 #endif