ceph/src/boost/libs/vmd/include/boost/vmd/seq/pop_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_SEQ_POP_FRONT_HPP)
   8 #define BOOST_VMD_SEQ_POP_FRONT_HPP
   9
  10 #include <boost/vmd/detail/setup.hpp>
  11
  12 #if BOOST_PP_VARIADICS
  13
  14 #include <boost/preprocessor/comparison/equal.hpp>
  15 #include <boost/preprocessor/control/iif.hpp>
  16 #include <boost/preprocessor/seq/pop_front.hpp>
  17 #include <boost/preprocessor/seq/size.hpp>
  18 #include <boost/vmd/empty.hpp>
  19
  20 /*
  21
  22   The succeeding comments in this file are in doxygen format.
  23
  24 */
  25
  26 /** \file
  27 */
  28
  29 /** \def BOOST_VMD_SEQ_POP_FRONT(seq)
  30
  31     \brief pops an element from the front of a seq.
  32
  33     seq = seq to pop an element from.
  34
  35     If the seq is an empty seq the result is undefined.
  36     If the seq is a single element the result is an empty seq.
  37     Otherwise the result is a seq after removing the first element.
  38 */
  39
  40 #define BOOST_VMD_SEQ_POP_FRONT(seq) \
  41     BOOST_PP_IIF \
  42         ( \
  43         BOOST_PP_EQUAL(BOOST_PP_SEQ_SIZE(seq),1), \
  44         BOOST_VMD_EMPTY, \
  45         BOOST_PP_SEQ_POP_FRONT \
  46         ) \
  47     (seq) \
  48 /**/
  49
  50 #endif /* BOOST_PP_VARIADICS */
  51 #endif /* BOOST_VMD_SEQ_POP_FRONT_HPP */