1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___RANGES_RBEGIN_H 11 #define _LIBCPP___RANGES_RBEGIN_H 12 13 #include <__concepts/class_or_enum.h> 14 #include <__concepts/same_as.h> 15 #include <__config> 16 #include <__iterator/concepts.h> 17 #include <__iterator/readable_traits.h> 18 #include <__iterator/reverse_iterator.h> 19 #include <__ranges/access.h> 20 #include <__utility/auto_cast.h> 21 #include <type_traits> 22 23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 24 # pragma GCC system_header 25 #endif 26 27 _LIBCPP_BEGIN_NAMESPACE_STD 28 29 #if _LIBCPP_STD_VER > 17 30 31 // [ranges.access.rbegin] 32 33 namespace ranges { 34 namespace __rbegin { 35 template <class _Tp> 36 concept __member_rbegin = 37 __can_borrow<_Tp> && 38 __workaround_52970<_Tp> && 39 requires(_Tp&& __t) { 40 { _LIBCPP_AUTO_CAST(__t.rbegin()) } -> input_or_output_iterator; 41 }; 42 43 void rbegin(auto&) = delete; 44 void rbegin(const auto&) = delete; 45 46 template <class _Tp> 47 concept __unqualified_rbegin = 48 !__member_rbegin<_Tp> && 49 __can_borrow<_Tp> && 50 __class_or_enum<remove_cvref_t<_Tp>> && 51 requires(_Tp&& __t) { 52 { _LIBCPP_AUTO_CAST(rbegin(__t)) } -> input_or_output_iterator; 53 }; 54 55 template <class _Tp> 56 concept __can_reverse = 57 __can_borrow<_Tp> && 58 !__member_rbegin<_Tp> && 59 !__unqualified_rbegin<_Tp> && 60 requires(_Tp&& __t) { 61 { ranges::begin(__t) } -> same_as<decltype(ranges::end(__t))>; 62 { ranges::begin(__t) } -> bidirectional_iterator; 63 }; 64 65 struct __fn { 66 template <class _Tp> 67 requires __member_rbegin<_Tp> 68 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 69 noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.rbegin()))) 70 { 71 return _LIBCPP_AUTO_CAST(__t.rbegin()); 72 } 73 74 template <class _Tp> 75 requires __unqualified_rbegin<_Tp> 76 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 77 noexcept(noexcept(_LIBCPP_AUTO_CAST(rbegin(__t)))) 78 { 79 return _LIBCPP_AUTO_CAST(rbegin(__t)); 80 } 81 82 template <class _Tp> 83 requires __can_reverse<_Tp> 84 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 85 noexcept(noexcept(ranges::end(__t))) 86 { 87 return std::make_reverse_iterator(ranges::end(__t)); 88 } 89 90 void operator()(auto&&) const = delete; 91 }; 92 } // namespace __rbegin 93 94 inline namespace __cpo { 95 inline constexpr auto rbegin = __rbegin::__fn{}; 96 } // namespace __cpo 97 } // namespace ranges 98 99 // [range.access.crbegin] 100 101 namespace ranges { 102 namespace __crbegin { 103 struct __fn { 104 template <class _Tp> 105 requires is_lvalue_reference_v<_Tp&&> 106 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 107 constexpr auto operator()(_Tp&& __t) const 108 noexcept(noexcept(ranges::rbegin(static_cast<const remove_reference_t<_Tp>&>(__t)))) 109 -> decltype( ranges::rbegin(static_cast<const remove_reference_t<_Tp>&>(__t))) 110 { return ranges::rbegin(static_cast<const remove_reference_t<_Tp>&>(__t)); } 111 112 template <class _Tp> 113 requires is_rvalue_reference_v<_Tp&&> 114 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 115 constexpr auto operator()(_Tp&& __t) const 116 noexcept(noexcept(ranges::rbegin(static_cast<const _Tp&&>(__t)))) 117 -> decltype( ranges::rbegin(static_cast<const _Tp&&>(__t))) 118 { return ranges::rbegin(static_cast<const _Tp&&>(__t)); } 119 }; 120 } // namespace __crbegin 121 122 inline namespace __cpo { 123 inline constexpr auto crbegin = __crbegin::__fn{}; 124 } // namespace __cpo 125 } // namespace ranges 126 127 #endif // _LIBCPP_STD_VER > 17 128 129 _LIBCPP_END_NAMESPACE_STD 130 131 #endif // _LIBCPP___RANGES_RBEGIN_H 132