llvm-project/libcxx/include/__iterator/iter_move.h

100 lines
2.7 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___ITERATOR_ITER_MOVE_H
#define _LIBCPP___ITERATOR_ITER_MOVE_H
#include <__concepts/class_or_enum.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__utility/forward.h>
#include <__utility/move.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
// [iterator.cust.move]
namespace ranges {
namespace __iter_move {
void iter_move();
template <class _Tp>
concept __unqualified_iter_move =
__class_or_enum<remove_cvref_t<_Tp>> &&
requires (_Tp&& __t) {
iter_move(std::forward<_Tp>(__t));
};
template<class _Tp>
concept __move_deref =
!__unqualified_iter_move<_Tp> &&
requires (_Tp&& __t) {
*__t;
requires is_lvalue_reference_v<decltype(*__t)>;
};
template<class _Tp>
concept __just_deref =
!__unqualified_iter_move<_Tp> &&
!__move_deref<_Tp> &&
requires (_Tp&& __t) {
*__t;
requires (!is_lvalue_reference_v<decltype(*__t)>);
};
// [iterator.cust.move]
struct __fn {
template<class _Ip>
requires __unqualified_iter_move<_Ip>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Ip&& __i) const
noexcept(noexcept(iter_move(std::forward<_Ip>(__i))))
{
return iter_move(std::forward<_Ip>(__i));
}
template<class _Ip>
requires __move_deref<_Ip>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Ip&& __i) const
noexcept(noexcept(std::move(*std::forward<_Ip>(__i))))
-> decltype( std::move(*std::forward<_Ip>(__i)))
{ return std::move(*std::forward<_Ip>(__i)); }
template<class _Ip>
requires __just_deref<_Ip>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Ip&& __i) const
noexcept(noexcept(*std::forward<_Ip>(__i)))
-> decltype( *std::forward<_Ip>(__i))
{ return *std::forward<_Ip>(__i); }
};
} // namespace __iter_move
inline namespace __cpo {
inline constexpr auto iter_move = __iter_move::__fn{};
} // namespace __cpo
} // namespace ranges
template<__dereferenceable _Tp>
requires requires(_Tp& __t) { { ranges::iter_move(__t) } -> __can_reference; }
using iter_rvalue_reference_t = decltype(ranges::iter_move(declval<_Tp&>()));
#endif // _LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ITERATOR_ITER_MOVE_H