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

#ifndef _LIBCUDACXX___ITERATOR_ITER_MOVE_H
#define _LIBCUDACXX___ITERATOR_ITER_MOVE_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/__concepts/class_or_enum.h>
#include <cuda/std/__iterator/iterator_traits.h>
#include <cuda/std/__type_traits/enable_if.h>
#include <cuda/std/__type_traits/is_reference.h>
#include <cuda/std/__type_traits/remove_cvref.h>
#include <cuda/std/__utility/declval.h>
#include <cuda/std/__utility/forward.h>
#include <cuda/std/__utility/move.h>

_CCCL_DIAG_PUSH
_CCCL_DIAG_SUPPRESS_CLANG("-Wvoid-ptr-dereference")

#if _CCCL_STD_VER > 2014

// [iterator.cust.move]

_LIBCUDACXX_BEGIN_NAMESPACE_RANGES
_LIBCUDACXX_BEGIN_NAMESPACE_CPO(__iter_move)

_LIBCUDACXX_INLINE_VISIBILITY void iter_move();

#  if _CCCL_STD_VER >= 2020
template <class _Tp>
concept __unqualified_iter_move =
  __class_or_enum<remove_cvref_t<_Tp>> && requires(_Tp&& __t) { iter_move(_CUDA_VSTD::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)>);
};

#  else // ^^^ _CCCL_STD_VER >= 2020 ^^^ / vvv _CCCL_STD_VER <= 2017 vvv

template <class _Tp>
_LIBCUDACXX_CONCEPT_FRAGMENT(
  __unqualified_iter_move_,
  requires(_Tp&& __t)(requires(__class_or_enum<remove_cvref_t<_Tp>>), (iter_move(_CUDA_VSTD::forward<_Tp>(__t)))));

template <class _Tp>
_LIBCUDACXX_CONCEPT __unqualified_iter_move = _LIBCUDACXX_FRAGMENT(__unqualified_iter_move_, _Tp);

template <class _Tp>
_LIBCUDACXX_CONCEPT_FRAGMENT(
  __move_deref_,
  requires(_Tp&& __t)(requires(!__unqualified_iter_move<_Tp>), requires(is_lvalue_reference_v<decltype(*__t)>)));

template <class _Tp>
_LIBCUDACXX_CONCEPT __move_deref = _LIBCUDACXX_FRAGMENT(__move_deref_, _Tp);

template <class _Tp>
_LIBCUDACXX_CONCEPT_FRAGMENT(
  __just_deref_,
  requires(_Tp&& __t)(requires(!__unqualified_iter_move<_Tp>),
                      requires(!__move_deref<_Tp>),
                      requires(!is_lvalue_reference_v<decltype(*__t)>)));

template <class _Tp>
_LIBCUDACXX_CONCEPT __just_deref = _LIBCUDACXX_FRAGMENT(__just_deref_, _Tp);
#  endif // _CCCL_STD_VER <= 2017

// [iterator.cust.move]

struct __fn
{
  _LIBCUDACXX_TEMPLATE(class _Ip)
  _LIBCUDACXX_REQUIRES(__unqualified_iter_move<_Ip>)
  _CCCL_NODISCARD _LIBCUDACXX_INLINE_VISIBILITY constexpr decltype(auto) operator()(_Ip&& __i) const
    noexcept(noexcept(iter_move(_CUDA_VSTD::forward<_Ip>(__i))))
  {
    return iter_move(_CUDA_VSTD::forward<_Ip>(__i));
  }

  _LIBCUDACXX_TEMPLATE(class _Ip)
  _LIBCUDACXX_REQUIRES(__move_deref<_Ip>)
  _CCCL_NODISCARD _LIBCUDACXX_INLINE_VISIBILITY constexpr auto operator()(_Ip&& __i) const
    noexcept(noexcept(_CUDA_VSTD::move(*_CUDA_VSTD::forward<_Ip>(__i))))
      -> decltype(_CUDA_VSTD::move(*_CUDA_VSTD::forward<_Ip>(__i)))
  {
    return _CUDA_VSTD::move(*_CUDA_VSTD::forward<_Ip>(__i));
  }

  _LIBCUDACXX_TEMPLATE(class _Ip)
  _LIBCUDACXX_REQUIRES(__just_deref<_Ip>)
  _CCCL_NODISCARD _LIBCUDACXX_INLINE_VISIBILITY constexpr auto operator()(_Ip&& __i) const
    noexcept(noexcept(*_CUDA_VSTD::forward<_Ip>(__i))) -> decltype(*_CUDA_VSTD::forward<_Ip>(__i))
  {
    return *_CUDA_VSTD::forward<_Ip>(__i);
  }
};
_LIBCUDACXX_END_NAMESPACE_CPO
inline namespace __cpo
{
_LIBCUDACXX_CPO_ACCESSIBILITY auto iter_move = __iter_move::__fn{};
} // namespace __cpo
_LIBCUDACXX_END_NAMESPACE_RANGES

_LIBCUDACXX_BEGIN_NAMESPACE_STD

#  if _CCCL_STD_VER >= 2020
template <__dereferenceable _Tp>
  requires requires(_Tp& __t) {
    {
      _CUDA_VRANGES::iter_move(__t)
    } -> __can_reference;
  }
using iter_rvalue_reference_t = decltype(_CUDA_VRANGES::iter_move(_CUDA_VSTD::declval<_Tp&>()));

#  else // ^^^ _CCCL_STD_VER >= 2020 ^^^ / vvv _CCCL_STD_VER <= 2017 vvv

template <class _Tp>
_LIBCUDACXX_CONCEPT_FRAGMENT(__can_iter_rvalue_reference_t_,
                             requires(_Tp& __t)(requires(__dereferenceable<_Tp>),
                                                requires(__can_reference<decltype(_CUDA_VRANGES::iter_move(__t))>)));

template <class _Tp>
_LIBCUDACXX_CONCEPT __can_iter_rvalue_reference_t = _LIBCUDACXX_FRAGMENT(__can_iter_rvalue_reference_t_, _Tp);

template <class _Tp>
using __iter_rvalue_reference_t = decltype(_CUDA_VRANGES::iter_move(_CUDA_VSTD::declval<_Tp&>()));

template <class _Tp>
using iter_rvalue_reference_t = enable_if_t<__can_iter_rvalue_reference_t<_Tp>, __iter_rvalue_reference_t<_Tp>>;
#  endif // _CCCL_STD_VER <= 2017

_LIBCUDACXX_END_NAMESPACE_STD

#endif // _CCCL_STD_VER > 2014

_CCCL_DIAG_POP

#endif // _LIBCUDACXX___ITERATOR_ITER_MOVE_H