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