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 <__cstddef/size_t.h>
14#include <__type_traits/is_integral.h>
15
16#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17# pragma GCC system_header
18#endif
19
20_LIBCPP_BEGIN_NAMESPACE_STD
21
22template <size_t...>
23struct __tuple_indices;
24
25template <class _IdxType, _IdxType... _Values>
26struct __integer_sequence {
27 template <template <class _OIdxType, _OIdxType...> class _ToIndexSeq, class _ToIndexType>
28 using __convert _LIBCPP_NODEBUG = _ToIndexSeq<_ToIndexType, _Values...>;
29
30 template <size_t _Sp>
31 using __to_tuple_indices _LIBCPP_NODEBUG = __tuple_indices<(_Values + _Sp)...>;
32};
33
34#if __has_builtin(__make_integer_seq)
35template <size_t _Ep, size_t _Sp>
36using __make_indices_imp _LIBCPP_NODEBUG =
37 typename __make_integer_seq<__integer_sequence, size_t, _Ep - _Sp>::template __to_tuple_indices<_Sp>;
38#elif __has_builtin(__integer_pack)
39template <size_t _Ep, size_t _Sp>
40using __make_indices_imp _LIBCPP_NODEBUG =
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
48template <class _Tp, _Tp... _Ip>
49struct 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
55template <size_t... _Ip>
56using index_sequence = integer_sequence<size_t, _Ip...>;
57
58# if __has_builtin(__make_integer_seq)
59
60template <class _Tp, _Tp _Ep>
61using make_integer_sequence _LIBCPP_NODEBUG = __make_integer_seq<integer_sequence, _Tp, _Ep>;
62
63# elif __has_builtin(__integer_pack)
64
65template <class _Tp, _Tp _SequenceSize>
66using 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
72template <size_t _Np>
73using make_index_sequence = make_integer_sequence<size_t, _Np>;
74
75template <class... _Tp>
76using 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.
80template <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