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