1 # /* Copyright (C) 2001 2 # * Housemarque Oy 3 # * http://www.housemarque.com 4 # * 5 # * Distributed under the Boost Software License, Version 1.0. (See 6 # * accompanying file LICENSE_1_0.txt or copy at 7 # * http://www.boost.org/LICENSE_1_0.txt) 8 # */ 9 # 10 # /* Revised by Paul Mensonides (2002-2011) */ 11 # /* Revised by Edward Diener (2011,2014,2020) */ 12 # 13 # /* See http://www.boost.org for most recent version. */ 14 # 15 # ifndef BOOST_PREPROCESSOR_TUPLE_ELEM_HPP 16 # define BOOST_PREPROCESSOR_TUPLE_ELEM_HPP 17 # 18 # include <boost/preprocessor/cat.hpp> 19 # include <boost/preprocessor/config/config.hpp> 20 # include <boost/preprocessor/facilities/expand.hpp> 21 # include <boost/preprocessor/facilities/overload.hpp> 22 # include <boost/preprocessor/tuple/rem.hpp> 23 # include <boost/preprocessor/variadic/elem.hpp> 24 # include <boost/preprocessor/tuple/detail/is_single_return.hpp> 25 # 26 # if BOOST_PP_VARIADICS_MSVC 27 # define BOOST_PP_TUPLE_ELEM(...) BOOST_PP_TUPLE_ELEM_I(BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_ELEM_O_, __VA_ARGS__), (__VA_ARGS__)) 28 # define BOOST_PP_TUPLE_ELEM_I(m, args) BOOST_PP_TUPLE_ELEM_II(m, args) 29 # define BOOST_PP_TUPLE_ELEM_II(m, args) BOOST_PP_CAT(m ## args,) 30 /* 31 Use BOOST_PP_REM_CAT if it is a single element tuple ( which might be empty ) 32 else use BOOST_PP_REM. This fixes a VC++ problem with an empty tuple and BOOST_PP_TUPLE_ELEM 33 functionality. See tuple_elem_bug_test.cxx. 34 */ 35 # define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) \ 36 BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_EXPAND(BOOST_PP_TUPLE_IS_SINGLE_RETURN(BOOST_PP_REM_CAT,BOOST_PP_REM,tuple) tuple)) \ 37 /**/ 38 # else 39 # define BOOST_PP_TUPLE_ELEM(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_ELEM_O_, __VA_ARGS__)(__VA_ARGS__) 40 # define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_REM tuple) 41 # endif 42 # define BOOST_PP_TUPLE_ELEM_O_3(size, n, tuple) BOOST_PP_TUPLE_ELEM_O_2(n, tuple) 43 # 44 # /* directly used elsewhere in Boost... */ 45 # 46 # define BOOST_PP_TUPLE_ELEM_1_0(a) a 47 # 48 # define BOOST_PP_TUPLE_ELEM_2_0(a, b) a 49 # define BOOST_PP_TUPLE_ELEM_2_1(a, b) b 50 # 51 # define BOOST_PP_TUPLE_ELEM_3_0(a, b, c) a 52 # define BOOST_PP_TUPLE_ELEM_3_1(a, b, c) b 53 # define BOOST_PP_TUPLE_ELEM_3_2(a, b, c) c 54 # 55 # endif 56