/*
 *  Copyright 2008-2012 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.
 */

#include <thrust/detail/config.h>
#include <thrust/system/detail/generic/distance.h>
#include <thrust/iterator/iterator_traits.h>

namespace thrust
{
namespace system
{
namespace detail
{
namespace generic
{
namespace detail
{

template<typename InputIterator>
  inline typename thrust::iterator_traits<InputIterator>::difference_type
    distance(InputIterator first, InputIterator last, thrust::incrementable_traversal_tag)
{
  typename thrust::iterator_traits<InputIterator>::difference_type result(0);

  while(first != last)
  {
    ++first;
    ++result;
  } // end while

  return result;
} // end advance()

template<typename InputIterator>
  inline typename thrust::iterator_traits<InputIterator>::difference_type
    distance(InputIterator first, InputIterator last, thrust::random_access_traversal_tag)
{
  return last - first;
} // end distance()

} // end detail

template<typename InputIterator>
  inline typename thrust::iterator_traits<InputIterator>::difference_type
    distance(InputIterator first, InputIterator last)
{
  // dispatch on iterator traversal
  return thrust::system::detail::generic::detail::distance(first, last,
    typename thrust::iterator_traversal<InputIterator>::type());
} // end advance()

} // end namespace generic
} // end namespace detail
} // end namespace system
} // end namespace thrust

