1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___TUPLE_TUPLE_ELEMENT_H 10 #define _LIBCPP___TUPLE_TUPLE_ELEMENT_H 11 12 #include <__config> 13 #include <__tuple/tuple_indices.h> 14 #include <__tuple/tuple_types.h> 15 #include <cstddef> 16 17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18 # pragma GCC system_header 19 #endif 20 21 _LIBCPP_BEGIN_NAMESPACE_STD 22 23 template <size_t _Ip, class _Tp> 24 struct _LIBCPP_TEMPLATE_VIS tuple_element; 25 26 template <size_t _Ip, class _Tp> 27 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, const _Tp> { 28 typedef _LIBCPP_NODEBUG const typename tuple_element<_Ip, _Tp>::type type; 29 }; 30 31 template <size_t _Ip, class _Tp> 32 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, volatile _Tp> { 33 typedef _LIBCPP_NODEBUG volatile typename tuple_element<_Ip, _Tp>::type type; 34 }; 35 36 template <size_t _Ip, class _Tp> 37 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, const volatile _Tp> { 38 typedef _LIBCPP_NODEBUG const volatile typename tuple_element<_Ip, _Tp>::type type; 39 }; 40 41 #ifndef _LIBCPP_CXX03_LANG 42 43 # if !__has_builtin(__type_pack_element) 44 45 namespace __indexer_detail { 46 47 template <size_t _Idx, class _Tp> 48 struct __indexed { 49 using type _LIBCPP_NODEBUG = _Tp; 50 }; 51 52 template <class _Types, class _Indexes> 53 struct __indexer; 54 55 template <class... _Types, size_t... _Idx> 56 struct __indexer<__tuple_types<_Types...>, __tuple_indices<_Idx...>> : __indexed<_Idx, _Types>... {}; 57 58 template <size_t _Idx, class _Tp> 59 __indexed<_Idx, _Tp> __at_index(__indexed<_Idx, _Tp> const&); 60 61 } // namespace __indexer_detail 62 63 template <size_t _Idx, class... _Types> 64 using __type_pack_element _LIBCPP_NODEBUG = typename decltype(__indexer_detail::__at_index<_Idx>( 65 __indexer_detail::__indexer< __tuple_types<_Types...>, 66 typename __make_tuple_indices<sizeof...(_Types)>::type >{}))::type; 67 # endif 68 69 template <size_t _Ip, class... _Types> 70 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, __tuple_types<_Types...> > { 71 static_assert(_Ip < sizeof...(_Types), "tuple_element index out of range"); 72 typedef _LIBCPP_NODEBUG __type_pack_element<_Ip, _Types...> type; 73 }; 74 75 # if _LIBCPP_STD_VER >= 14 76 template <size_t _Ip, class... _Tp> 77 using tuple_element_t _LIBCPP_NODEBUG = typename tuple_element<_Ip, _Tp...>::type; 78 # endif 79 80 #endif // _LIBCPP_CXX03_LANG 81 82 _LIBCPP_END_NAMESPACE_STD 83 84 #endif // _LIBCPP___TUPLE_TUPLE_ELEMENT_H 85