/*
 *  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.
 */

#pragma once

#include <thrust/detail/config.h>
#include <thrust/detail/type_traits.h>
#include <thrust/iterator/detail/tagged_iterator.h>
#include <thrust/detail/pointer.h>

namespace thrust
{
namespace detail
{


// we can retag an iterator if FromTag converts to ToTag
// or vice versa
template<typename FromTag, typename ToTag>
  struct is_retaggable
    : integral_constant<
        bool,
        (is_convertible<FromTag,ToTag>::value || is_convertible<ToTag,FromTag>::value)
      >
{};


template<typename FromTag, typename ToTag, typename Result>
  struct enable_if_retaggable
    : enable_if<
        is_retaggable<FromTag,ToTag>::value,
        Result
      >
{}; // end enable_if_retaggable


} // end detail


template<typename Tag, typename Iterator>
  thrust::detail::tagged_iterator<Iterator,Tag>
    reinterpret_tag(Iterator iter)
{
  return thrust::detail::tagged_iterator<Iterator,Tag>(iter);
} // end reinterpret_tag()


// specialization for raw pointer
template<typename Tag, typename T>
  thrust::pointer<T,Tag>
    reinterpret_tag(T *ptr)
{
  return thrust::pointer<T,Tag>(ptr);
} // end reinterpret_tag()


// specialization for thrust::pointer
template<typename Tag, typename T, typename OtherTag, typename Reference, typename Derived>
  thrust::pointer<T,Tag>
    reinterpret_tag(thrust::pointer<T,OtherTag,Reference,Derived> ptr)
{
  return reinterpret_tag<Tag>(ptr.get());
} // end reinterpret_tag()


// avoid deeply-nested tagged_iterator
template<typename Tag, typename BaseIterator, typename OtherTag>
  thrust::detail::tagged_iterator<BaseIterator,Tag>
    reinterpret_tag(thrust::detail::tagged_iterator<BaseIterator,OtherTag> iter)
{
  return reinterpret_tag<Tag>(iter.base());
} // end reinterpret_tag()


template<typename Tag, typename Iterator>
  typename thrust::detail::enable_if_retaggable<
    typename thrust::iterator_system<Iterator>::type,
    Tag,
    thrust::detail::tagged_iterator<Iterator,Tag>
  >::type
    retag(Iterator iter)
{
  return reinterpret_tag<Tag>(iter);
} // end retag()


// specialization for raw pointer
template<typename Tag, typename T>
  typename thrust::detail::enable_if_retaggable<
    typename thrust::iterator_system<T*>::type,
    Tag,
    thrust::pointer<T,Tag>
  >::type
    retag(T *ptr)
{
  return reinterpret_tag<Tag>(ptr);
} // end retag()


// specialization for thrust::pointer
template<typename Tag, typename T, typename OtherTag>
  typename thrust::detail::enable_if_retaggable<
    OtherTag,
    Tag,
    thrust::pointer<T,Tag>
  >::type
    retag(thrust::pointer<T,OtherTag> ptr)
{
  return reinterpret_tag<Tag>(ptr);
} // end retag()


// avoid deeply-nested tagged_iterator
template<typename Tag, typename BaseIterator, typename OtherTag>
  typename thrust::detail::enable_if_retaggable<
    OtherTag,
    Tag,
    thrust::detail::tagged_iterator<BaseIterator,Tag>
  >::type
    retag(thrust::detail::tagged_iterator<BaseIterator,OtherTag> iter)
{
  return reinterpret_tag<Tag>(iter);
} // end retag()


} // end thrust