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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-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___RANGES_RBEGIN_H11#define _LIBCPP___RANGES_RBEGIN_H12 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_header28#endif29 30_LIBCPP_BEGIN_NAMESPACE_STD31 32#if _LIBCPP_STD_VER >= 2033 34// [ranges.access.rbegin]35 36namespace ranges {37namespace __rbegin {38template <class _Tp>39concept __member_rbegin = __can_borrow<_Tp> && requires(_Tp&& __t) {40 { _LIBCPP_AUTO_CAST(__t.rbegin()) } -> input_or_output_iterator;41};42 43void rbegin() = delete;44 45template <class _Tp>46concept __unqualified_rbegin =47 !__member_rbegin<_Tp> && __can_borrow<_Tp> && __class_or_enum<remove_cvref_t<_Tp>> && requires(_Tp&& __t) {48 { _LIBCPP_AUTO_CAST(rbegin(__t)) } -> input_or_output_iterator;49 };50 51template <class _Tp>52concept __can_reverse =53 __can_borrow<_Tp> && !__member_rbegin<_Tp> && !__unqualified_rbegin<_Tp> && requires(_Tp&& __t) {54 { ranges::begin(__t) } -> same_as<decltype(ranges::end(__t))>;55 { ranges::begin(__t) } -> bidirectional_iterator;56 };57 58struct __fn {59 template <class _Tp>60 requires __member_rbegin<_Tp>61 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const62 noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.rbegin()))) {63 return _LIBCPP_AUTO_CAST(__t.rbegin());64 }65 66 template <class _Tp>67 requires __unqualified_rbegin<_Tp>68 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const69 noexcept(noexcept(_LIBCPP_AUTO_CAST(rbegin(__t)))) {70 return _LIBCPP_AUTO_CAST(rbegin(__t));71 }72 73 template <class _Tp>74 requires __can_reverse<_Tp>75 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const noexcept(noexcept(ranges::end(__t))) {76 return std::make_reverse_iterator(ranges::end(__t));77 }78 79 void operator()(auto&&) const = delete;80};81} // namespace __rbegin82 83inline namespace __cpo {84inline constexpr auto rbegin = __rbegin::__fn{};85} // namespace __cpo86} // namespace ranges87 88// [range.access.crbegin]89 90namespace ranges {91namespace __crbegin {92struct __fn {93 template <class _Tp>94 requires is_lvalue_reference_v<_Tp&&>95 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const96 noexcept(noexcept(ranges::rbegin(static_cast<const remove_reference_t<_Tp>&>(__t))))97 -> decltype(ranges::rbegin(static_cast<const remove_reference_t<_Tp>&>(__t))) {98 return ranges::rbegin(static_cast<const remove_reference_t<_Tp>&>(__t));99 }100 101 template <class _Tp>102 requires is_rvalue_reference_v<_Tp&&>103 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const104 noexcept(noexcept(ranges::rbegin(static_cast<const _Tp&&>(__t))))105 -> decltype(ranges::rbegin(static_cast<const _Tp&&>(__t))) {106 return ranges::rbegin(static_cast<const _Tp&&>(__t));107 }108};109} // namespace __crbegin110 111inline namespace __cpo {112inline constexpr auto crbegin = __crbegin::__fn{};113} // namespace __cpo114} // namespace ranges115 116#endif // _LIBCPP_STD_VER >= 20117 118_LIBCPP_END_NAMESPACE_STD119 120#endif // _LIBCPP___RANGES_RBEGIN_H121