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// -*- 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 <__config>
#include <__iterator/iterator_traits.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <concepts> // __class_or_enum
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
// [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(_VSTD::forward<_Tp>(__t));
};
// [iterator.cust.move]/1
// The name ranges::iter_move denotes a customization point object.
// The expression ranges::iter_move(E) for a subexpression E is
// expression-equivalent to:
struct __fn {
// [iterator.cust.move]/1.1
// iter_move(E), if E has class or enumeration type and iter_move(E) is a
// well-formed expression when treated as an unevaluated operand, [...]
template<class _Ip>
requires __class_or_enum<remove_cvref_t<_Ip>> && __unqualified_iter_move<_Ip>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Ip&& __i) const
noexcept(noexcept(iter_move(_VSTD::forward<_Ip>(__i))))
{
return iter_move(_VSTD::forward<_Ip>(__i));
}
// [iterator.cust.move]/1.2
// Otherwise, if the expression *E is well-formed:
// 1.2.1 if *E is an lvalue, std::move(*E);
// 1.2.2 otherwise, *E.
template<class _Ip>
requires (!(__class_or_enum<remove_cvref_t<_Ip>> && __unqualified_iter_move<_Ip>)) &&
requires(_Ip&& __i) { *_VSTD::forward<_Ip>(__i); }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Ip&& __i) const
noexcept(noexcept(*_VSTD::forward<_Ip>(__i)))
{
if constexpr (is_lvalue_reference_v<decltype(*_VSTD::forward<_Ip>(__i))>) {
return _VSTD::move(*_VSTD::forward<_Ip>(__i));
} else {
return *_VSTD::forward<_Ip>(__i);
}
}
// [iterator.cust.move]/1.3
// Otherwise, ranges::iter_move(E) is ill-formed.
};
} // 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 // !defined(_LIBCPP_HAS_NO_CONCEPTS)
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ITERATOR_ITER_MOVE_H
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