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___UTILITY_INTEGER_SEQUENCE_H 10 #define _LIBCPP___UTILITY_INTEGER_SEQUENCE_H 11 12 #include <__config> 13 #include <__type_traits/is_integral.h> 14 #include <cstddef> 15 16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17 # pragma GCC system_header 18 #endif 19 20 _LIBCPP_BEGIN_NAMESPACE_STD 21 22 template <size_t...> 23 struct __tuple_indices; 24 25 template <class _IdxType, _IdxType... _Values> 26 struct __integer_sequence { 27 template <template <class _OIdxType, _OIdxType...> class _ToIndexSeq, class _ToIndexType> 28 using __convert = _ToIndexSeq<_ToIndexType, _Values...>; 29 30 template <size_t _Sp> 31 using __to_tuple_indices = __tuple_indices<(_Values + _Sp)...>; 32 }; 33 34 #if !__has_builtin(__make_integer_seq) || defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE) 35 36 namespace __detail { 37 38 template <typename _Tp, size_t... _Extra> 39 struct __repeat; 40 template <typename _Tp, _Tp... _Np, size_t... _Extra> 41 struct __repeat<__integer_sequence<_Tp, _Np...>, _Extra...> { 42 typedef _LIBCPP_NODEBUG __integer_sequence< 43 _Tp, 44 _Np..., 45 sizeof...(_Np) + _Np..., 46 2 * sizeof...(_Np) + _Np..., 47 3 * sizeof...(_Np) + _Np..., 48 4 * sizeof...(_Np) + _Np..., 49 5 * sizeof...(_Np) + _Np..., 50 6 * sizeof...(_Np) + _Np..., 51 7 * sizeof...(_Np) + _Np..., 52 _Extra...> 53 type; 54 }; 55 56 template <size_t _Np> 57 struct __parity; 58 template <size_t _Np> 59 struct __make : __parity<_Np % 8>::template __pmake<_Np> {}; 60 61 // clang-format off 62 template<> struct __make<0> { typedef __integer_sequence<size_t> type; }; 63 template<> struct __make<1> { typedef __integer_sequence<size_t, 0> type; }; 64 template<> struct __make<2> { typedef __integer_sequence<size_t, 0, 1> type; }; 65 template<> struct __make<3> { typedef __integer_sequence<size_t, 0, 1, 2> type; }; 66 template<> struct __make<4> { typedef __integer_sequence<size_t, 0, 1, 2, 3> type; }; 67 template<> struct __make<5> { typedef __integer_sequence<size_t, 0, 1, 2, 3, 4> type; }; 68 template<> struct __make<6> { typedef __integer_sequence<size_t, 0, 1, 2, 3, 4, 5> type; }; 69 template<> struct __make<7> { typedef __integer_sequence<size_t, 0, 1, 2, 3, 4, 5, 6> type; }; 70 71 template<> struct __parity<0> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type> {}; }; 72 template<> struct __parity<1> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 1> {}; }; 73 template<> struct __parity<2> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 2, _Np - 1> {}; }; 74 template<> struct __parity<3> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 3, _Np - 2, _Np - 1> {}; }; 75 template<> struct __parity<4> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; }; 76 template<> struct __parity<5> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; }; 77 template<> struct __parity<6> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; }; 78 template<> struct __parity<7> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 7, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; }; 79 // clang-format on 80 81 } // namespace __detail 82 83 #endif 84 85 #if __has_builtin(__make_integer_seq) 86 template <size_t _Ep, size_t _Sp> 87 using __make_indices_imp = 88 typename __make_integer_seq<__integer_sequence, size_t, _Ep - _Sp>::template __to_tuple_indices<_Sp>; 89 #else 90 template <size_t _Ep, size_t _Sp> 91 using __make_indices_imp = typename __detail::__make<_Ep - _Sp>::type::template __to_tuple_indices<_Sp>; 92 93 #endif 94 95 #if _LIBCPP_STD_VER >= 14 96 97 template <class _Tp, _Tp... _Ip> 98 struct _LIBCPP_TEMPLATE_VIS integer_sequence { 99 typedef _Tp value_type; 100 static_assert(is_integral<_Tp>::value, "std::integer_sequence can only be instantiated with an integral type"); 101 static _LIBCPP_HIDE_FROM_ABI constexpr size_t size() noexcept { return sizeof...(_Ip); } 102 }; 103 104 template <size_t... _Ip> 105 using index_sequence = integer_sequence<size_t, _Ip...>; 106 107 # if __has_builtin(__make_integer_seq) && !defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE) 108 109 template <class _Tp, _Tp _Ep> 110 using __make_integer_sequence _LIBCPP_NODEBUG = __make_integer_seq<integer_sequence, _Tp, _Ep>; 111 112 # else 113 114 template <typename _Tp, _Tp _Np> 115 using __make_integer_sequence_unchecked _LIBCPP_NODEBUG = 116 typename __detail::__make<_Np>::type::template __convert<integer_sequence, _Tp>; 117 118 template <class _Tp, _Tp _Ep> 119 struct __make_integer_sequence_checked { 120 static_assert(is_integral<_Tp>::value, "std::make_integer_sequence can only be instantiated with an integral type"); 121 static_assert(0 <= _Ep, "std::make_integer_sequence must have a non-negative sequence length"); 122 // Workaround GCC bug by preventing bad installations when 0 <= _Ep 123 // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68929 124 typedef _LIBCPP_NODEBUG __make_integer_sequence_unchecked<_Tp, 0 <= _Ep ? _Ep : 0> type; 125 }; 126 127 template <class _Tp, _Tp _Ep> 128 using __make_integer_sequence _LIBCPP_NODEBUG = typename __make_integer_sequence_checked<_Tp, _Ep>::type; 129 130 # endif 131 132 template <class _Tp, _Tp _Np> 133 using make_integer_sequence = __make_integer_sequence<_Tp, _Np>; 134 135 template <size_t _Np> 136 using make_index_sequence = make_integer_sequence<size_t, _Np>; 137 138 template <class... _Tp> 139 using index_sequence_for = make_index_sequence<sizeof...(_Tp)>; 140 141 # if _LIBCPP_STD_VER >= 20 142 // Executes __func for every element in an index_sequence. 143 template <size_t... _Index, class _Function> 144 _LIBCPP_HIDE_FROM_ABI constexpr void __for_each_index_sequence(index_sequence<_Index...>, _Function __func) { 145 (__func.template operator()<_Index>(), ...); 146 } 147 # endif // _LIBCPP_STD_VER >= 20 148 149 #endif // _LIBCPP_STD_VER >= 14 150 151 _LIBCPP_END_NAMESPACE_STD 152 153 #endif // _LIBCPP___UTILITY_INTEGER_SEQUENCE_H 154