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) 35 template <size_t _Ep, size_t _Sp> 36 using __make_indices_imp = 37 typename __make_integer_seq<__integer_sequence, size_t, _Ep - _Sp>::template __to_tuple_indices<_Sp>; 38 #elif __has_builtin(__integer_pack) 39 template <size_t _Ep, size_t _Sp> 40 using __make_indices_imp = 41 typename __integer_sequence<size_t, __integer_pack(_Ep - _Sp)...>::template __to_tuple_indices<_Sp>; 42 #else 43 # error "No known way to get an integer pack from the compiler" 44 #endif 45 46 #if _LIBCPP_STD_VER >= 14 47 48 template <class _Tp, _Tp... _Ip> 49 struct _LIBCPP_TEMPLATE_VIS integer_sequence { 50 typedef _Tp value_type; 51 static_assert(is_integral<_Tp>::value, "std::integer_sequence can only be instantiated with an integral type"); 52 static _LIBCPP_HIDE_FROM_ABI constexpr size_t size() noexcept { return sizeof...(_Ip); } 53 }; 54 55 template <size_t... _Ip> 56 using index_sequence = integer_sequence<size_t, _Ip...>; 57 58 # if __has_builtin(__make_integer_seq) 59 60 template <class _Tp, _Tp _Ep> 61 using make_integer_sequence _LIBCPP_NODEBUG = __make_integer_seq<integer_sequence, _Tp, _Ep>; 62 63 # elif __has_builtin(__integer_pack) 64 65 template <class _Tp, _Tp _SequenceSize> 66 using make_integer_sequence _LIBCPP_NODEBUG = integer_sequence<_Tp, __integer_pack(_SequenceSize)...>; 67 68 # else 69 # error "No known way to get an integer pack from the compiler" 70 # endif 71 72 template <size_t _Np> 73 using make_index_sequence = make_integer_sequence<size_t, _Np>; 74 75 template <class... _Tp> 76 using index_sequence_for = make_index_sequence<sizeof...(_Tp)>; 77 78 # if _LIBCPP_STD_VER >= 20 79 // Executes __func for every element in an index_sequence. 80 template <size_t... _Index, class _Function> 81 _LIBCPP_HIDE_FROM_ABI constexpr void __for_each_index_sequence(index_sequence<_Index...>, _Function __func) { 82 (__func.template operator()<_Index>(), ...); 83 } 84 # endif // _LIBCPP_STD_VER >= 20 85 86 #endif // _LIBCPP_STD_VER >= 14 87 88 _LIBCPP_END_NAMESPACE_STD 89 90 #endif // _LIBCPP___UTILITY_INTEGER_SEQUENCE_H 91