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_POP_FRONT_HPP) 8 #define BOOST_VMD_TUPLE_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/tuple/pop_front.hpp> 17 #include <boost/preprocessor/tuple/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_TUPLE_POP_FRONT(tuple) 30 31 \brief pops an element from the front of a tuple. 32 33 tuple = tuple to pop an element from. 34 35 If the tuple is an empty tuple the result is undefined. 36 If the tuple is a single element the result is an empty tuple. 37 Otherwise the result is a tuple after removing the first element. 38 */ 39 40 #define BOOST_VMD_TUPLE_POP_FRONT(tuple) \ 41 BOOST_PP_IIF \ 42 ( \ 43 BOOST_PP_EQUAL(BOOST_PP_TUPLE_SIZE(tuple),1), \ 44 BOOST_VMD_EMPTY, \ 45 BOOST_PP_TUPLE_POP_FRONT \ 46 ) \ 47 (tuple) \ 48 /**/ 49 50 /** \def BOOST_VMD_TUPLE_POP_FRONT_Z(z,tuple) 51 52 \brief pops an element from the front of a tuple. It reenters BOOST_PP_REPEAT with maximum efficiency. 53 54 z = the next available BOOST_PP_REPEAT dimension. <br/> 55 tuple = tuple to pop an element from. 56 57 If the tuple is an empty tuple the result is undefined. 58 If the tuple is a single element the result is an empty tuple. 59 Otherwise the result is a tuple after removing the first element. 60 */ 61 62 #define BOOST_VMD_TUPLE_POP_FRONT_Z(z,tuple) \ 63 BOOST_PP_IIF \ 64 ( \ 65 BOOST_PP_EQUAL(BOOST_PP_TUPLE_SIZE(tuple),1), \ 66 BOOST_VMD_EMPTY, \ 67 BOOST_PP_TUPLE_POP_FRONT_Z \ 68 ) \ 69 (z,tuple) \ 70 /**/ 71 72 #endif /* BOOST_PP_VARIADICS */ 73 #endif /* BOOST_VMD_TUPLE_POP_FRONT_HPP */ 74