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> 14 15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 16 #pragma GCC system_header 17 #endif 18 19 _LIBCPP_BEGIN_NAMESPACE_STD 20 21 #if _LIBCPP_STD_VER > 11 22 23 template<class _Tp, _Tp... _Ip> 24 struct _LIBCPP_TEMPLATE_VIS integer_sequence 25 { 26 typedef _Tp value_type; 27 static_assert( is_integral<_Tp>::value, 28 "std::integer_sequence can only be instantiated with an integral type" ); 29 static 30 _LIBCPP_INLINE_VISIBILITY 31 constexpr 32 size_t 33 size() noexcept { return sizeof...(_Ip); } 34 }; 35 36 template<size_t... _Ip> 37 using index_sequence = integer_sequence<size_t, _Ip...>; 38 39 #if __has_builtin(__make_integer_seq) && !defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE) 40 41 template <class _Tp, _Tp _Ep> 42 using __make_integer_sequence _LIBCPP_NODEBUG = __make_integer_seq<integer_sequence, _Tp, _Ep>; 43 44 #else 45 46 template<typename _Tp, _Tp _Np> using __make_integer_sequence_unchecked _LIBCPP_NODEBUG = 47 typename __detail::__make<_Np>::type::template __convert<integer_sequence, _Tp>; 48 49 template <class _Tp, _Tp _Ep> 50 struct __make_integer_sequence_checked 51 { 52 static_assert(is_integral<_Tp>::value, 53 "std::make_integer_sequence can only be instantiated with an integral type" ); 54 static_assert(0 <= _Ep, "std::make_integer_sequence must have a non-negative sequence length"); 55 // Workaround GCC bug by preventing bad installations when 0 <= _Ep 56 // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68929 57 typedef _LIBCPP_NODEBUG __make_integer_sequence_unchecked<_Tp, 0 <= _Ep ? _Ep : 0> type; 58 }; 59 60 template <class _Tp, _Tp _Ep> 61 using __make_integer_sequence _LIBCPP_NODEBUG = typename __make_integer_sequence_checked<_Tp, _Ep>::type; 62 63 #endif 64 65 template<class _Tp, _Tp _Np> 66 using make_integer_sequence = __make_integer_sequence<_Tp, _Np>; 67 68 template<size_t _Np> 69 using make_index_sequence = make_integer_sequence<size_t, _Np>; 70 71 template<class... _Tp> 72 using index_sequence_for = make_index_sequence<sizeof...(_Tp)>; 73 74 #endif // _LIBCPP_STD_VER > 11 75 76 _LIBCPP_END_NAMESPACE_STD 77 78 #endif // _LIBCPP___UTILITY_INTEGER_SEQUENCE_H 79