boost/preprocessor/seq/first_n.hpp

   1 # /* **************************************************************************
   2 #  *                                                                          *
   3 #  *     (C) Copyright Paul Mensonides 2002.
   4 #  *     Distributed under the Boost Software License, Version 1.0. (See
   5 #  *     accompanying file LICENSE_1_0.txt or copy at
   6 #  *     http://www.boost.org/LICENSE_1_0.txt)
   7 #  *                                                                          *
   8 #  ************************************************************************** */
   9 #
  10 # /* See http://www.boost.org for most recent version. */
  11 #
  12 # ifndef BOOST_PREPROCESSOR_SEQ_FIRST_N_HPP
  13 # define BOOST_PREPROCESSOR_SEQ_FIRST_N_HPP
  14 #
  15 # include <boost/preprocessor/config/config.hpp>
  16 # include <boost/preprocessor/control/if.hpp>
  17 # include <boost/preprocessor/seq/detail/split.hpp>
  18 # include <boost/preprocessor/tuple/eat.hpp>
  19 # include <boost/preprocessor/tuple/elem.hpp>
  20 #
  21 # /* BOOST_PP_SEQ_FIRST_N */
  22 #
  23 # if ~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_EDG()
  24 #    define BOOST_PP_SEQ_FIRST_N(n, seq) BOOST_PP_IF(n, BOOST_PP_TUPLE_ELEM, BOOST_PP_TUPLE_EAT_3)(2, 0, BOOST_PP_SEQ_SPLIT(n, seq (nil)))
  25 # else
  26 #    define BOOST_PP_SEQ_FIRST_N(n, seq) BOOST_PP_SEQ_FIRST_N_I(n, seq)
  27 #    define BOOST_PP_SEQ_FIRST_N_I(n, seq) BOOST_PP_IF(n, BOOST_PP_TUPLE_ELEM, BOOST_PP_TUPLE_EAT_3)(2, 0, BOOST_PP_SEQ_SPLIT(n, seq (nil)))
  28 # endif
  29 #
  30 # endif