/*
 *  Copyright 2008-2021 NVIDIA Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

/*! \file
 *  \brief Algorithms for asynchronously iterating over the elements of a range.
 */

#pragma once

#include <thrust/detail/config.h>

#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 <thrust/detail/cpp14_required.h>

#if _CCCL_STD_VER >= 2014

#  include <thrust/detail/select_system.h>
#  include <thrust/detail/static_assert.h>
#  include <thrust/event.h>
#  include <thrust/system/detail/adl/async/for_each.h>
#  include <thrust/type_traits/remove_cvref.h>

THRUST_NAMESPACE_BEGIN

namespace async
{

/*! \cond
 */

namespace unimplemented
{

template <typename DerivedPolicy, typename ForwardIt, typename Sentinel, typename UnaryFunction>
_CCCL_HOST event<DerivedPolicy>
async_for_each(thrust::execution_policy<DerivedPolicy>&, ForwardIt, Sentinel, UnaryFunction)
{
  THRUST_STATIC_ASSERT_MSG((thrust::detail::depend_on_instantiation<ForwardIt, false>::value),
                           "this algorithm is not implemented for the specified system");
  return {};
}

} // namespace unimplemented

namespace for_each_detail
{

using thrust::async::unimplemented::async_for_each;

struct for_each_fn final
{
  template <typename DerivedPolicy, typename ForwardIt, typename Sentinel, typename UnaryFunction>
  _CCCL_HOST static auto
  call(thrust::detail::execution_policy_base<DerivedPolicy> const& exec,
       ForwardIt&& first,
       Sentinel&& last,
       UnaryFunction&& f)
    // ADL dispatch.
    THRUST_RETURNS(async_for_each(thrust::detail::derived_cast(thrust::detail::strip_const(exec)),
                                  THRUST_FWD(first),
                                  THRUST_FWD(last),
                                  THRUST_FWD(f)))

      template <typename ForwardIt, typename Sentinel, typename UnaryFunction>
      _CCCL_HOST static auto call(ForwardIt&& first, Sentinel&& last, UnaryFunction&& f)
        THRUST_RETURNS(for_each_fn::call(
          thrust::detail::select_system(typename iterator_system<remove_cvref_t<ForwardIt>>::type{}),
          THRUST_FWD(first),
          THRUST_FWD(last),
          THRUST_FWD(f)))

          template <typename... Args>
          _CCCL_NODISCARD _CCCL_HOST auto operator()(Args&&... args) const THRUST_RETURNS(call(THRUST_FWD(args)...))
};

} // namespace for_each_detail

THRUST_INLINE_CONSTANT for_each_detail::for_each_fn for_each{};

/*! \endcond
 */

} // namespace async

THRUST_NAMESPACE_END

#endif
