//===----------------------------------------------------------------------===//
//
// 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___CONCEPTS_RELATION_H
#define _LIBCUDACXX___CONCEPTS_RELATION_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/concept_macros.h>
#include <cuda/std/__concepts/predicate.h>

_LIBCUDACXX_BEGIN_NAMESPACE_STD

#if !defined(_CCCL_NO_CONCEPTS)

// [concept.relation]

template <class _Rp, class _Tp, class _Up>
concept relation =
  predicate<_Rp, _Tp, _Tp> && predicate<_Rp, _Up, _Up> && predicate<_Rp, _Tp, _Up> && predicate<_Rp, _Up, _Tp>;

// [concept.equiv]

template <class _Rp, class _Tp, class _Up>
concept equivalence_relation = relation<_Rp, _Tp, _Up>;

// [concept.strictweakorder]

template <class _Rp, class _Tp, class _Up>
concept strict_weak_order = relation<_Rp, _Tp, _Up>;

#elif !defined(_CCCL_NO_VARIABLE_TEMPLATES) // ^^^ !_CCCL_NO_CONCEPTS ^^^

template <class _Rp, class _Tp, class _Up>
_CCCL_CONCEPT_FRAGMENT(
  __relation_,
  requires()(requires(predicate<_Rp, _Tp, _Tp>),
             requires(predicate<_Rp, _Up, _Up>),
             requires(predicate<_Rp, _Tp, _Up>),
             requires(predicate<_Rp, _Up, _Tp>)));

template <class _Rp, class _Tp, class _Up>
_CCCL_CONCEPT relation = _CCCL_FRAGMENT(__relation_, _Rp, _Tp, _Up);

// [concept.equiv]

template <class _Rp, class _Tp, class _Up>
_CCCL_CONCEPT equivalence_relation = relation<_Rp, _Tp, _Up>;

// [concept.strictweakorder]

template <class _Rp, class _Tp, class _Up>
_CCCL_CONCEPT strict_weak_order = relation<_Rp, _Tp, _Up>;

#endif // ^^^ !_CCCL_NO_VARIABLE_TEMPLATES

_LIBCUDACXX_END_NAMESPACE_STD

#endif // _LIBCUDACXX___CONCEPTS_RELATION_H
