/*
 *  Copyright 2008-2013 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>
#include <thrust/system/detail/generic/sequence.h>
#include <thrust/iterator/iterator_traits.h>
#include <thrust/tabulate.h>

THRUST_NAMESPACE_BEGIN
namespace system
{
namespace detail
{
namespace generic
{


template<typename DerivedPolicy, typename ForwardIterator>
THRUST_HOST_DEVICE
  void sequence(thrust::execution_policy<DerivedPolicy> &exec,
                ForwardIterator first,
                ForwardIterator last)
{
  using T = typename thrust::iterator_traits<ForwardIterator>::value_type;

  thrust::sequence(exec, first, last, T(0));
} // end sequence()


template<typename DerivedPolicy, typename ForwardIterator, typename T>
THRUST_HOST_DEVICE
  void sequence(thrust::execution_policy<DerivedPolicy> &exec,
                ForwardIterator first,
                ForwardIterator last,
                T init)
{
  thrust::sequence(exec, first, last, init, T(1));
} // end sequence()

namespace detail
{
template <typename T, typename = void>
struct compute_sequence_value
{
  T init;
  T step;

  THRUST_EXEC_CHECK_DISABLE
  THRUST_HOST_DEVICE
  T operator()(std::size_t i) const
  {
    return init + step * i;
  }
};
template <typename T>
struct compute_sequence_value<T, typename std::enable_if<std::is_arithmetic<T>::value>::type>
{
  T init;
  T step;

  THRUST_EXEC_CHECK_DISABLE
  THRUST_HOST_DEVICE
  T operator()(std::size_t i) const
  {
    return init + step * static_cast<T>(i);
  }
};
}

template<typename DerivedPolicy, typename ForwardIterator, typename T>
THRUST_HOST_DEVICE
  void sequence(thrust::execution_policy<DerivedPolicy> &exec,
                ForwardIterator first,
                ForwardIterator last,
                T init,
                T step)
{

  thrust::tabulate(exec,
                   first,
                   last,
                   detail::compute_sequence_value<T>{std::move(init),
                                                     std::move(step)});
} // end sequence()


} // end namespace generic
} // end namespace detail
} // end namespace system
THRUST_NAMESPACE_END
