//===----------------------------------------------------------------------===//
//
// 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
// SPDX-FileCopyrightText: Copyright (c) 2023 NVIDIA CORPORATION & AFFILIATES.
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCUDACXX___TYPE_TRAITS_IS_SWAPPABLE_H
#define _LIBCUDACXX___TYPE_TRAITS_IS_SWAPPABLE_H

#include <cuda/std/detail/__config>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <cuda/std/__type_traits/add_lvalue_reference.h>
#include <cuda/std/__type_traits/conditional.h>
#include <cuda/std/__type_traits/enable_if.h>
#include <cuda/std/__type_traits/is_move_assignable.h>
#include <cuda/std/__type_traits/is_move_constructible.h>
#include <cuda/std/__type_traits/is_nothrow_move_assignable.h>
#include <cuda/std/__type_traits/is_nothrow_move_constructible.h>
#include <cuda/std/__type_traits/is_referenceable.h>
#include <cuda/std/__type_traits/is_same.h>
#include <cuda/std/__type_traits/is_void.h>
#include <cuda/std/__type_traits/nat.h>
#include <cuda/std/__utility/declval.h>
#include <cuda/std/cstddef>

_LIBCUDACXX_BEGIN_NAMESPACE_STD

template <class _Tp>
struct __is_swappable;
template <class _Tp>
struct __is_nothrow_swappable;

template <class _Tp>
using __swap_result_t =
  __enable_if_t<_LIBCUDACXX_TRAIT(is_move_constructible, _Tp) && _LIBCUDACXX_TRAIT(is_move_assignable, _Tp)>;

template <class _Tp>
inline _LIBCUDACXX_INLINE_VISIBILITY _CCCL_CONSTEXPR_CXX14 __swap_result_t<_Tp> swap(_Tp& __x, _Tp& __y) noexcept(
  _LIBCUDACXX_TRAIT(is_nothrow_move_constructible, _Tp) && _LIBCUDACXX_TRAIT(is_nothrow_move_assignable, _Tp));

template <class _Tp, size_t _Np>
inline _LIBCUDACXX_INLINE_VISIBILITY _CCCL_CONSTEXPR_CXX14 __enable_if_t<__is_swappable<_Tp>::value>
  swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) noexcept(__is_nothrow_swappable<_Tp>::value);

namespace __detail
{
// ALL generic swap overloads MUST already have a declaration available at this point.

template <class _Tp,
          class _Up     = _Tp,
          bool _NotVoid = !_LIBCUDACXX_TRAIT(is_void, _Tp) && !_LIBCUDACXX_TRAIT(is_void, _Up)>
struct __swappable_with
{
  template <class _LHS, class _RHS>
  _LIBCUDACXX_INLINE_VISIBILITY static decltype(swap(_CUDA_VSTD::declval<_LHS>(), _CUDA_VSTD::declval<_RHS>()))
  __test_swap(int);
  template <class, class>
  _LIBCUDACXX_INLINE_VISIBILITY static __nat __test_swap(long);

  // Extra parens are needed for the C++03 definition of decltype.
  typedef decltype((__test_swap<_Tp, _Up>(0))) __swap1;
  typedef decltype((__test_swap<_Up, _Tp>(0))) __swap2;

  static const bool value = _IsNotSame<__swap1, __nat>::value && _IsNotSame<__swap2, __nat>::value;
};

template <class _Tp, class _Up>
struct __swappable_with<_Tp, _Up, false> : false_type
{};

template <class _Tp, class _Up = _Tp, bool _Swappable = __swappable_with<_Tp, _Up>::value>
struct __nothrow_swappable_with
{
  static const bool value = noexcept(swap(_CUDA_VSTD::declval<_Tp>(), _CUDA_VSTD::declval<_Up>()))&& noexcept(
    swap(_CUDA_VSTD::declval<_Up>(), _CUDA_VSTD::declval<_Tp>()));
};

template <class _Tp, class _Up>
struct __nothrow_swappable_with<_Tp, _Up, false> : false_type
{};

} // namespace __detail

template <class _Tp>
struct __is_swappable : public integral_constant<bool, __detail::__swappable_with<_Tp&>::value>
{};

template <class _Tp>
struct __is_nothrow_swappable : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp&>::value>
{};

#if _CCCL_STD_VER > 2011

template <class _Tp, class _Up>
struct _LIBCUDACXX_TEMPLATE_VIS is_swappable_with
    : public integral_constant<bool, __detail::__swappable_with<_Tp, _Up>::value>
{};

template <class _Tp>
struct _LIBCUDACXX_TEMPLATE_VIS is_swappable
    : public __conditional_t<__libcpp_is_referenceable<_Tp>::value,
                             is_swappable_with<__add_lvalue_reference_t<_Tp>, __add_lvalue_reference_t<_Tp>>,
                             false_type>
{};

template <class _Tp, class _Up>
struct _LIBCUDACXX_TEMPLATE_VIS is_nothrow_swappable_with
    : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp, _Up>::value>
{};

template <class _Tp>
struct _LIBCUDACXX_TEMPLATE_VIS is_nothrow_swappable
    : public __conditional_t<__libcpp_is_referenceable<_Tp>::value,
                             is_nothrow_swappable_with<__add_lvalue_reference_t<_Tp>, __add_lvalue_reference_t<_Tp>>,
                             false_type>
{};

template <class _Tp, class _Up>
_LIBCUDACXX_INLINE_VAR constexpr bool is_swappable_with_v = is_swappable_with<_Tp, _Up>::value;

template <class _Tp>
_LIBCUDACXX_INLINE_VAR constexpr bool is_swappable_v = is_swappable<_Tp>::value;

template <class _Tp, class _Up>
_LIBCUDACXX_INLINE_VAR constexpr bool is_nothrow_swappable_with_v = is_nothrow_swappable_with<_Tp, _Up>::value;

template <class _Tp>
_LIBCUDACXX_INLINE_VAR constexpr bool is_nothrow_swappable_v = is_nothrow_swappable<_Tp>::value;

#endif // _CCCL_STD_VER > 2011

_LIBCUDACXX_END_NAMESPACE_STD

#endif // _LIBCUDACXX___TYPE_TRAITS_IS_SWAPPABLE_H
