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/*
* 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/detail/type_traits.h>
#include <thrust/iterator/iterator_traits.h>
#include <thrust/detail/use_default.h>
#include <thrust/iterator/iterator_facade.h>
THRUST_NAMESPACE_BEGIN
// forward declaration of iterator_adaptor for iterator_adaptor_base below
template<typename Derived,
typename Base,
typename Value,
typename System,
typename Traversal,
typename Reference,
typename Difference
>
class iterator_adaptor;
namespace detail
{
// If T is use_default, return the result of invoking
// DefaultNullaryFn, otherwise return T.
// XXX rename to dflt_help
template <class T, class DefaultNullaryFn>
struct ia_dflt_help
: thrust::detail::eval_if<
thrust::detail::is_same<T, thrust::use_default>::value
, DefaultNullaryFn
, thrust::detail::identity_<T>
>
{
}; // end ia_dflt_help
// A metafunction which computes an iterator_adaptor's base class,
// a specialization of iterator_facade.
template<typename Derived,
typename Base,
typename Value,
typename System,
typename Traversal,
typename Reference,
typename Difference
>
struct iterator_adaptor_base
{
typedef typename ia_dflt_help<
Value,
iterator_value<Base>
>::type value;
typedef typename ia_dflt_help<
System,
thrust::iterator_system<Base>
>::type system;
typedef typename ia_dflt_help<
Traversal,
thrust::iterator_traversal<Base>
>::type traversal;
typedef typename ia_dflt_help<
Reference,
thrust::detail::eval_if<
thrust::detail::is_same<Value,use_default>::value,
thrust::iterator_reference<Base>,
thrust::detail::add_reference<Value>
>
>::type reference;
typedef typename ia_dflt_help<
Difference,
iterator_difference<Base>
>::type difference;
typedef thrust::iterator_facade<
Derived,
value,
system,
traversal,
reference,
difference
> type;
}; // end iterator_adaptor_base
} // end detail
THRUST_NAMESPACE_END
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