/*
 *  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>

#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/internal_functional.h>
#include <thrust/detail/static_assert.h>
#include <thrust/for_each.h>
#include <thrust/iterator/iterator_traits.h>
#include <thrust/system/detail/generic/generate.h>

#if !_THRUST_HAS_DEVICE_SYSTEM_STD
#  include <type_traits>
#endif

THRUST_NAMESPACE_BEGIN
namespace system
{
namespace detail
{
namespace generic
{

template <typename ExecutionPolicy, typename ForwardIterator, typename Generator>
THRUST_HOST_DEVICE void
generate(thrust::execution_policy<ExecutionPolicy>& exec, ForwardIterator first, ForwardIterator last, Generator gen)
{
  // this static assert is necessary due to a workaround in generate_functor
  // it takes a const reference to accept temporaries from proxy iterators
  // and then const_casts the constness away
  //
  // this had the weird side effect of allowing generate (and fill, and whatever
  // else is implemented in terms of generate) to fill through const iterators.
  // this might become unnecessary once Thrust is C++11-and-above only, since the
  // other solution is to take an rvalue reference in a second overload of
  // operator() of the function object, but until we support pre-11, this is a
  // nice solution that validates the const_cast and doesn't take away any
  // functionality.
  THRUST_STATIC_ASSERT_MSG(
    !_THRUST_STD::is_const<
      _THRUST_STD::remove_reference_t<typename thrust::iterator_traits<ForwardIterator>::reference>>::value,
    "generating to `const` iterators is not allowed");
  thrust::for_each(exec, first, last, typename thrust::detail::generate_functor<ExecutionPolicy, Generator>::type(gen));
} // end generate()

template <typename ExecutionPolicy, typename OutputIterator, typename Size, typename Generator>
THRUST_HOST_DEVICE OutputIterator
generate_n(thrust::execution_policy<ExecutionPolicy>& exec, OutputIterator first, Size n, Generator gen)
{
  // this static assert is necessary due to a workaround in generate_functor
  // it takes a const reference to accept temporaries from proxy iterators
  // and then const_casts the constness away
  //
  // this had the weird side effect of allowing generate (and fill, and whatever
  // else is implemented in terms of generate) to fill through const iterators.
  // this might become unnecessary once Thrust is C++11-and-above only, since the
  // other solution is to take an rvalue reference in a second overload of
  // operator() of the function object, but until we support pre-11, this is a
  // nice solution that validates the const_cast and doesn't take away any
  // functionality.
  THRUST_STATIC_ASSERT_MSG(
    !_THRUST_STD::is_const<
      _THRUST_STD::remove_reference_t<typename thrust::iterator_traits<OutputIterator>::reference>>::value,
    "generating to `const` iterators is not allowed");
  return thrust::for_each_n(
    exec, first, n, typename thrust::detail::generate_functor<ExecutionPolicy, Generator>::type(gen));
} // end generate()

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