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 = __can_borrow<_Tp> && __workaround_52970<_Tp> && requires(_Tp&& __t) { 41 ranges::rbegin(__t); 42 { _LIBCPP_AUTO_CAST(__t.rend()) } -> sentinel_for<decltype(ranges::rbegin(__t))>; 43 }; 44 45 void rend(auto&) = delete; 46 void rend(const auto&) = delete; 47 48 template <class _Tp> 49 concept __unqualified_rend = 50 !__member_rend<_Tp> && __can_borrow<_Tp> && __class_or_enum<remove_cvref_t<_Tp>> && requires(_Tp&& __t) { 51 ranges::rbegin(__t); 52 { _LIBCPP_AUTO_CAST(rend(__t)) } -> sentinel_for<decltype(ranges::rbegin(__t))>; 53 }; 54 55 template <class _Tp> 56 concept __can_reverse = __can_borrow<_Tp> && !__member_rend<_Tp> && !__unqualified_rend<_Tp> && requires(_Tp&& __t) { 57 { ranges::begin(__t) } -> same_as<decltype(ranges::end(__t))>; 58 { ranges::begin(__t) } -> bidirectional_iterator; 59 }; 60 61 class __fn { 62 public: 63 template <class _Tp> 64 requires __member_rend<_Tp> 65 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 66 noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.rend()))) { 67 return _LIBCPP_AUTO_CAST(__t.rend()); 68 } 69 70 template <class _Tp> 71 requires __unqualified_rend<_Tp> 72 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 73 noexcept(noexcept(_LIBCPP_AUTO_CAST(rend(__t)))) { 74 return _LIBCPP_AUTO_CAST(rend(__t)); 75 } 76 77 template <class _Tp> 78 requires __can_reverse<_Tp> 79 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 80 noexcept(noexcept(ranges::begin(__t))) { 81 return std::make_reverse_iterator(ranges::begin(__t)); 82 } 83 84 void operator()(auto&&) const = delete; 85 }; 86 } // namespace __rend 87 88 inline namespace __cpo { 89 inline constexpr auto rend = __rend::__fn{}; 90 } // namespace __cpo 91 } // namespace ranges 92 93 // [range.access.crend] 94 95 namespace ranges { 96 namespace __crend { 97 struct __fn { 98 template <class _Tp> 99 requires is_lvalue_reference_v<_Tp&&> 100 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 101 noexcept(noexcept(ranges::rend(static_cast<const remove_reference_t<_Tp>&>(__t)))) 102 -> decltype(ranges::rend(static_cast<const remove_reference_t<_Tp>&>(__t))) { 103 return ranges::rend(static_cast<const remove_reference_t<_Tp>&>(__t)); 104 } 105 106 template <class _Tp> 107 requires is_rvalue_reference_v<_Tp&&> 108 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const 109 noexcept(noexcept(ranges::rend(static_cast<const _Tp&&>(__t)))) 110 -> decltype(ranges::rend(static_cast<const _Tp&&>(__t))) { 111 return ranges::rend(static_cast<const _Tp&&>(__t)); 112 } 113 }; 114 } // namespace __crend 115 116 inline namespace __cpo { 117 inline constexpr auto crend = __crend::__fn{}; 118 } // namespace __cpo 119 } // namespace ranges 120 121 #endif // _LIBCPP_STD_VER >= 20 122 123 _LIBCPP_END_NAMESPACE_STD 124 125 #endif // _LIBCPP___RANGES_REND_H 126