llvm-project/libcxx/include/__ranges/rbegin.h

131 lines
3.8 KiB
C++

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___RANGES_RBEGIN_H
#define _LIBCPP___RANGES_RBEGIN_H
#include <__concepts/class_or_enum.h>
#include <__concepts/same_as.h>
#include <__config>
#include <__iterator/concepts.h>
#include <__iterator/readable_traits.h>
#include <__iterator/reverse_iterator.h>
#include <__ranges/access.h>
#include <__utility/auto_cast.h>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
// [ranges.access.rbegin]
namespace ranges {
namespace __rbegin {
template <class _Tp>
concept __member_rbegin =
__can_borrow<_Tp> &&
__workaround_52970<_Tp> &&
requires(_Tp&& __t) {
{ _LIBCPP_AUTO_CAST(__t.rbegin()) } -> input_or_output_iterator;
};
void rbegin(auto&) = delete;
void rbegin(const auto&) = delete;
template <class _Tp>
concept __unqualified_rbegin =
!__member_rbegin<_Tp> &&
__can_borrow<_Tp> &&
__class_or_enum<remove_cvref_t<_Tp>> &&
requires(_Tp&& __t) {
{ _LIBCPP_AUTO_CAST(rbegin(__t)) } -> input_or_output_iterator;
};
template <class _Tp>
concept __can_reverse =
__can_borrow<_Tp> &&
!__member_rbegin<_Tp> &&
!__unqualified_rbegin<_Tp> &&
requires(_Tp&& __t) {
{ ranges::begin(__t) } -> same_as<decltype(ranges::end(__t))>;
{ ranges::begin(__t) } -> bidirectional_iterator;
};
struct __fn {
template <class _Tp>
requires __member_rbegin<_Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.rbegin())))
{
return _LIBCPP_AUTO_CAST(__t.rbegin());
}
template <class _Tp>
requires __unqualified_rbegin<_Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
noexcept(noexcept(_LIBCPP_AUTO_CAST(rbegin(__t))))
{
return _LIBCPP_AUTO_CAST(rbegin(__t));
}
template <class _Tp>
requires __can_reverse<_Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
noexcept(noexcept(ranges::end(__t)))
{
return std::make_reverse_iterator(ranges::end(__t));
}
void operator()(auto&&) const = delete;
};
} // namespace __rbegin
inline namespace __cpo {
inline constexpr auto rbegin = __rbegin::__fn{};
} // namespace __cpo
} // namespace ranges
// [range.access.crbegin]
namespace ranges {
namespace __crbegin {
struct __fn {
template <class _Tp>
requires is_lvalue_reference_v<_Tp&&>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
constexpr auto operator()(_Tp&& __t) const
noexcept(noexcept(ranges::rbegin(static_cast<const remove_reference_t<_Tp>&>(__t))))
-> decltype( ranges::rbegin(static_cast<const remove_reference_t<_Tp>&>(__t)))
{ return ranges::rbegin(static_cast<const remove_reference_t<_Tp>&>(__t)); }
template <class _Tp>
requires is_rvalue_reference_v<_Tp&&>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
constexpr auto operator()(_Tp&& __t) const
noexcept(noexcept(ranges::rbegin(static_cast<const _Tp&&>(__t))))
-> decltype( ranges::rbegin(static_cast<const _Tp&&>(__t)))
{ return ranges::rbegin(static_cast<const _Tp&&>(__t)); }
};
} // namespace __crbegin
inline namespace __cpo {
inline constexpr auto crbegin = __crbegin::__fn{};
} // namespace __cpo
} // namespace ranges
#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___RANGES_RBEGIN_H