boost/vmd/tuple/push_back.hpp

//  (C) Copyright Edward Diener 2015
//  Use, modification and distribution are subject to the Boost Software License,
//  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
//  http://www.boost.org/LICENSE_1_0.txt).
#if !defined(BOOST_VMD_TUPLE_PUSH_BACK_HPP)
#define BOOST_VMD_TUPLE_PUSH_BACK_HPP
#include <boost/vmd/detail/setup.hpp>
#if BOOST_PP_VARIADICS
#include <boost/preprocessor/control/iif.hpp>
#include <boost/preprocessor/tuple/push_back.hpp>
#include <boost/vmd/identity.hpp>
#include <boost/vmd/is_empty.hpp>
/*
  The succeeding comments in this file are in doxygen format.
*/
/** \file
*/
/** \def BOOST_VMD_TUPLE_PUSH_BACK(tuple,elem)
    \brief appends an element to the end of a tuple. 
    tuple = tuple to to append an element to.
    elem  = element to append.
    If the tuple is an empty tuple the result is a tuple with the single element.
    Otherwise the result is a tuple after adding the element to the end.
*/
#define BOOST_VMD_TUPLE_PUSH_BACK(tuple,elem) \
    BOOST_VMD_IDENTITY_RESULT \
        ( \
        BOOST_PP_IIF \
            ( \
            BOOST_VMD_IS_EMPTY(tuple), \
            BOOST_VMD_IDENTITY((elem)), \
            BOOST_PP_TUPLE_PUSH_BACK \
            ) \
        (tuple,elem) \
        ) \
/**/
#endif /* BOOST_PP_VARIADICS */
#endif /* BOOST_VMD_TUPLE_PUSH_BACK_HPP */