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. <br/> 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 */ 54