/*
 *  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.
 */

#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/iterator/iterator_adaptor.h>
#include <thrust/iterator/transform_output_iterator.h>

THRUST_NAMESPACE_BEGIN

template <typename UnaryFunction, typename OutputIterator>
class transform_output_iterator;

namespace detail
{

// Proxy reference that uses Unary Function to transform the rhs of assigment
// operator before writing the result to OutputIterator
template <typename UnaryFunction, typename OutputIterator>
class transform_output_iterator_proxy
{
public:
  _CCCL_HOST_DEVICE transform_output_iterator_proxy(const OutputIterator& out, UnaryFunction fun)
      : out(out)
      , fun(fun)
  {}

  _CCCL_EXEC_CHECK_DISABLE
  template <typename T>
  _CCCL_HOST_DEVICE transform_output_iterator_proxy operator=(const T& x)
  {
    *out = fun(x);
    return *this;
  }

private:
  OutputIterator out;
  UnaryFunction fun;
};

// Compute the iterator_adaptor instantiation to be used for transform_output_iterator
template <typename UnaryFunction, typename OutputIterator>
struct transform_output_iterator_base
{
  using type =
    thrust::iterator_adaptor<transform_output_iterator<UnaryFunction, OutputIterator>,
                             OutputIterator,
                             thrust::use_default,
                             thrust::use_default,
                             thrust::use_default,
                             transform_output_iterator_proxy<UnaryFunction, OutputIterator>>;
};

// Register transform_output_iterator_proxy with 'is_proxy_reference' from
// type_traits to enable its use with algorithms.
template <class UnaryFunction, class OutputIterator>
struct is_proxy_reference<transform_output_iterator_proxy<UnaryFunction, OutputIterator>>
    : public thrust::detail::true_type
{};

} // namespace detail
THRUST_NAMESPACE_END
