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//===----------------------------------------------------------------------===//
//
// 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___CONCEPTS_SWAPPABLE_H
#define _LIBCPP___CONCEPTS_SWAPPABLE_H
#include <__concepts/assignable.h>
#include <__concepts/class_or_enum.h>
#include <__concepts/common_reference_with.h>
#include <__concepts/constructible.h>
#include <__config>
#include <__utility/exchange.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 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
// [concept.swappable]
namespace ranges::__swap {
// Deleted to inhibit ADL
template<class _Tp>
void swap(_Tp&, _Tp&) = delete;
// [1]
template<class _Tp, class _Up>
concept __unqualified_swappable_with =
(__class_or_enum<remove_cvref_t<_Tp>> || __class_or_enum<remove_cvref_t<_Up>>) &&
requires(_Tp&& __t, _Up&& __u) {
swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u));
};
struct __fn;
template<class _Tp, class _Up, size_t _Size>
concept __swappable_arrays =
!__unqualified_swappable_with<_Tp(&)[_Size], _Up(&)[_Size]> &&
extent_v<_Tp> == extent_v<_Up> &&
requires(_Tp(& __t)[_Size], _Up(& __u)[_Size], const __fn& __swap) {
__swap(__t[0], __u[0]);
};
template<class _Tp>
concept __exchangeable =
!__unqualified_swappable_with<_Tp&, _Tp&> &&
move_constructible<_Tp> &&
assignable_from<_Tp&, _Tp>;
struct __fn {
// 2.1 `S` is `(void)swap(E1, E2)`* if `E1` or `E2` has class or enumeration type and...
// *The name `swap` is used here unqualified.
template<class _Tp, class _Up>
requires __unqualified_swappable_with<_Tp, _Up>
constexpr void operator()(_Tp&& __t, _Up&& __u) const
noexcept(noexcept(swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
{
swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u));
}
// 2.2 Otherwise, if `E1` and `E2` are lvalues of array types with equal extent and...
template<class _Tp, class _Up, size_t _Size>
requires __swappable_arrays<_Tp, _Up, _Size>
constexpr void operator()(_Tp(& __t)[_Size], _Up(& __u)[_Size]) const
noexcept(noexcept((*this)(*__t, *__u)))
{
// TODO(cjdb): replace with `ranges::swap_ranges`.
for (size_t __i = 0; __i < _Size; ++__i) {
(*this)(__t[__i], __u[__i]);
}
}
// 2.3 Otherwise, if `E1` and `E2` are lvalues of the same type `T` that models...
template<__exchangeable _Tp>
constexpr void operator()(_Tp& __x, _Tp& __y) const
noexcept(is_nothrow_move_constructible_v<_Tp> && is_nothrow_move_assignable_v<_Tp>)
{
__y = _VSTD::exchange(__x, _VSTD::move(__y));
}
};
} // namespace ranges::__swap
namespace ranges::inline __cpo {
inline constexpr auto swap = __swap::__fn{};
} // namespace ranges::__cpo
template<class _Tp>
concept swappable = requires(_Tp& __a, _Tp& __b) { ranges::swap(__a, __b); };
template<class _Tp, class _Up>
concept swappable_with =
common_reference_with<_Tp, _Up> &&
requires(_Tp&& __t, _Up&& __u) {
ranges::swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Tp>(__t));
ranges::swap(_VSTD::forward<_Up>(__u), _VSTD::forward<_Up>(__u));
ranges::swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u));
ranges::swap(_VSTD::forward<_Up>(__u), _VSTD::forward<_Tp>(__t));
};
#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___CONCEPTS_SWAPPABLE_H
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