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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_SWAP_H
#define _LIBCPP___ITERATOR_ITER_SWAP_H
#include <__config>
#include <__iterator/concepts.h>
#include <__iterator/iter_move.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/readable_traits.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <concepts>
#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
// [iter.cust.swap]
namespace ranges {
namespace __iter_swap {
template<class _I1, class _I2>
void iter_swap(_I1, _I2) = delete;
template<class _T1, class _T2>
concept __unqualified_iter_swap =
(__class_or_enum<remove_cvref_t<_T1>> || __class_or_enum<remove_cvref_t<_T2>>) &&
requires (_T1&& __x, _T2&& __y) {
iter_swap(_VSTD::forward<_T1>(__x), _VSTD::forward<_T2>(__y));
};
template<class _T1, class _T2>
concept __readable_swappable =
indirectly_readable<_T1> && indirectly_readable<_T2> &&
swappable_with<iter_reference_t<_T1>, iter_reference_t<_T2>>;
struct __fn {
template <class _T1, class _T2>
requires __unqualified_iter_swap<_T1, _T2>
_LIBCPP_HIDE_FROM_ABI
constexpr void operator()(_T1&& __x, _T2&& __y) const
noexcept(noexcept(iter_swap(_VSTD::forward<_T1>(__x), _VSTD::forward<_T2>(__y))))
{
(void)iter_swap(_VSTD::forward<_T1>(__x), _VSTD::forward<_T2>(__y));
}
template <class _T1, class _T2>
requires (!__unqualified_iter_swap<_T1, _T2>) &&
__readable_swappable<_T1, _T2>
_LIBCPP_HIDE_FROM_ABI
constexpr void operator()(_T1&& __x, _T2&& __y) const
noexcept(noexcept(ranges::swap(*_VSTD::forward<_T1>(__x), *_VSTD::forward<_T2>(__y))))
{
ranges::swap(*_VSTD::forward<_T1>(__x), *_VSTD::forward<_T2>(__y));
}
template <class _T1, class _T2>
requires (!__unqualified_iter_swap<_T1, _T2> &&
!__readable_swappable<_T1, _T2>) &&
indirectly_movable_storable<_T1, _T2> &&
indirectly_movable_storable<_T2, _T1>
_LIBCPP_HIDE_FROM_ABI
constexpr void operator()(_T1&& __x, _T2&& __y) const
noexcept(noexcept(iter_value_t<_T2>(ranges::iter_move(__y))) &&
noexcept(*__y = ranges::iter_move(__x)) &&
noexcept(*_VSTD::forward<_T1>(__x) = declval<iter_value_t<_T2>>()))
{
iter_value_t<_T2> __old(ranges::iter_move(__y));
*__y = ranges::iter_move(__x);
*_VSTD::forward<_T1>(__x) = _VSTD::move(__old);
}
};
} // namespace __iter_swap
inline namespace __cpo {
inline constexpr auto iter_swap = __iter_swap::__fn{};
} // namespace __cpo
} // namespace ranges
template<class _I1, class _I2 = _I1>
concept indirectly_swappable =
indirectly_readable<_I1> && indirectly_readable<_I2> &&
requires(const _I1 __i1, const _I2 __i2) {
ranges::iter_swap(__i1, __i1);
ranges::iter_swap(__i2, __i2);
ranges::iter_swap(__i1, __i2);
ranges::iter_swap(__i2, __i1);
};
#endif // _LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ITERATOR_ITER_SWAP_H
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