ceph/src/boost/libs/vmd/include/boost/vmd/tuple/push_front.hpp

   1
   2 //  (C) Copyright Edward Diener 2015
   3 //  Use, modification and distribution are subject to the Boost Software License,
   4 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   5 //  http://www.boost.org/LICENSE_1_0.txt).
   6
   7 #if !defined(BOOST_VMD_TUPLE_PUSH_FRONT_HPP)
   8 #define BOOST_VMD_TUPLE_PUSH_FRONT_HPP
   9
  10 #include <boost/vmd/detail/setup.hpp>
  11
  12 #if BOOST_PP_VARIADICS
  13
  14 #include <boost/preprocessor/control/iif.hpp>
  15 #include <boost/preprocessor/tuple/push_front.hpp>
  16 #include <boost/vmd/identity.hpp>
  17 #include <boost/vmd/is_empty.hpp>
  18
  19 /*
  20
  21   The succeeding comments in this file are in doxygen format.
  22
  23 */
  24
  25 /** \file
  26 */
  27
  28 /** \def BOOST_VMD_TUPLE_PUSH_FRONT(tuple,elem)
  29
  30     \brief inserts an element at the beginning of a tuple.
  31
  32     tuple = tuple to insert an element at.
  33     elem  = element to insert.
  34
  35     If the tuple is an empty tuple the result is a tuple with the single element.
  36     Otherwise the result is a tuple after inserting the element at the beginning.
  37 */
  38
  39 #define BOOST_VMD_TUPLE_PUSH_FRONT(tuple,elem) \
  40     BOOST_VMD_IDENTITY_RESULT \
  41         ( \
  42         BOOST_PP_IIF \
  43             ( \
  44             BOOST_VMD_IS_EMPTY(tuple), \
  45             BOOST_VMD_IDENTITY((elem)), \
  46             BOOST_PP_TUPLE_PUSH_FRONT \
  47             ) \
  48         (tuple,elem) \
  49         ) \
  50 /**/
  51
  52 #endif /* BOOST_PP_VARIADICS */
  53 #endif /* BOOST_VMD_TUPLE_PUSH_FRONT_HPP */