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_REND_H 11 #define _LIBCPP___RANGES_REND_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 <__ranges/rbegin.h> 21 #include <__type_traits/decay.h> 22 #include <__type_traits/is_reference.h> 23 #include <__type_traits/remove_cvref.h> 24 #include <__type_traits/remove_reference.h> 25 #include <__utility/auto_cast.h> 26 27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 28 # pragma GCC system_header 29 #endif 30 31 _LIBCPP_BEGIN_NAMESPACE_STD 32 33 #if _LIBCPP_STD_VER >= 20 34 35 // [range.access.rend] 36 37 namespace ranges { 38 namespace __rend { 39 template <class _Tp> 40 concept __member_rend = 41 __can_borrow<_Tp> && 42 __workaround_52970<_Tp> && 43 requires(_Tp&& __t) { 44 ranges::rbegin(__t); 45 { _LIBCPP_AUTO_CAST(__t.rend()) } -> sentinel_for<decltype(ranges::rbegin(__t))>; 46 }; 47 48 void rend(auto&) = delete; 49 void rend(const auto&) = delete; 50 51 template <class _Tp> 52 concept __unqualified_rend = 53 !__member_rend<_Tp> && 54 __can_borrow<_Tp> && 55 __class_or_enum<remove_cvref_t<_Tp>> && 56 requires(_Tp&& __t) { 57 ranges::rbegin(__t); 58 { _LIBCPP_AUTO_CAST(rend(__t)) } -> sentinel_for<decltype(ranges::rbegin(__t))>; 59 }; 60 61 template <class _Tp> 62 concept __can_reverse = 63 __can_borrow<_Tp> && 64 !__member_rend<_Tp> && 65 !__unqualified_rend<_Tp> && 66 requires(_Tp&& __t) { 67 { ranges::begin(__t) } -> same_as<decltype(ranges::end(__t))>; 68 { ranges::begin(__t) } -> bidirectional_iterator; 69 }; 70 71 class __fn { 72 public: 73 template <class _Tp> 74 requires __member_rend<_Tp> 75 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 76 noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.rend()))) 77 { 78 return _LIBCPP_AUTO_CAST(__t.rend()); 79 } 80 81 template <class _Tp> 82 requires __unqualified_rend<_Tp> 83 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 84 noexcept(noexcept(_LIBCPP_AUTO_CAST(rend(__t)))) 85 { 86 return _LIBCPP_AUTO_CAST(rend(__t)); 87 } 88 89 template <class _Tp> 90 requires __can_reverse<_Tp> 91 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 92 noexcept(noexcept(ranges::begin(__t))) 93 { 94 return std::make_reverse_iterator(ranges::begin(__t)); 95 } 96 97 void operator()(auto&&) const = delete; 98 }; 99 } // namespace __rend 100 101 inline namespace __cpo { 102 inline constexpr auto rend = __rend::__fn{}; 103 } // namespace __cpo 104 } // namespace ranges 105 106 // [range.access.crend] 107 108 namespace ranges { 109 namespace __crend { 110 struct __fn { 111 template <class _Tp> 112 requires is_lvalue_reference_v<_Tp&&> 113 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 114 constexpr auto operator()(_Tp&& __t) const 115 noexcept(noexcept(ranges::rend(static_cast<const remove_reference_t<_Tp>&>(__t)))) 116 -> decltype( ranges::rend(static_cast<const remove_reference_t<_Tp>&>(__t))) 117 { return ranges::rend(static_cast<const remove_reference_t<_Tp>&>(__t)); } 118 119 template <class _Tp> 120 requires is_rvalue_reference_v<_Tp&&> 121 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 122 constexpr auto operator()(_Tp&& __t) const 123 noexcept(noexcept(ranges::rend(static_cast<const _Tp&&>(__t)))) 124 -> decltype( ranges::rend(static_cast<const _Tp&&>(__t))) 125 { return ranges::rend(static_cast<const _Tp&&>(__t)); } 126 }; 127 } // namespace __crend 128 129 inline namespace __cpo { 130 inline constexpr auto crend = __crend::__fn{}; 131 } // namespace __cpo 132 } // namespace ranges 133 134 #endif // _LIBCPP_STD_VER >= 20 135 136 _LIBCPP_END_NAMESPACE_STD 137 138 #endif // _LIBCPP___RANGES_REND_H 139