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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/detail/host_system_tag.h>
#include <thrust/iterator/detail/device_system_tag.h>
#include <thrust/iterator/detail/any_system_tag.h>
#include <thrust/iterator/iterator_categories.h>
#include <thrust/iterator/detail/iterator_traversal_tags.h>
#include <thrust/iterator/detail/is_iterator_category.h>
#include <thrust/iterator/detail/iterator_category_with_system_and_traversal.h>
#include <thrust/iterator/detail/iterator_category_to_traversal.h>
THRUST_NAMESPACE_BEGIN
namespace detail
{
// adapted from http://www.boost.org/doc/libs/1_37_0/libs/iterator/doc/iterator_facade.html#iterator-category
//
// in our implementation, R need not be a reference type to result in a category
// derived from forward_XXX_iterator_tag
//
// iterator-category(T,V,R) :=
// if(T is convertible to input_host_iterator_tag
// || T is convertible to output_host_iterator_tag
// || T is convertible to input_device_iterator_tag
// || T is convertible to output_device_iterator_tag
// )
// return T
//
// else if (T is not convertible to incrementable_traversal_tag)
// the program is ill-formed
//
// else return a type X satisfying the following two constraints:
//
// 1. X is convertible to X1, and not to any more-derived
// type, where X1 is defined by:
//
// if (T is convertible to forward_traversal_tag)
// {
// if (T is convertible to random_access_traversal_tag)
// X1 = random_access_host_iterator_tag
// else if (T is convertible to bidirectional_traversal_tag)
// X1 = bidirectional_host_iterator_tag
// else
// X1 = forward_host_iterator_tag
// }
// else
// {
// if (T is convertible to single_pass_traversal_tag
// && R is convertible to V)
// X1 = input_host_iterator_tag
// else
// X1 = T
// }
//
// 2. category-to-traversal(X) is convertible to the most
// derived traversal tag type to which X is also convertible,
// and not to any more-derived traversal tag type.
template<typename System, typename Traversal, typename ValueParam, typename Reference>
struct iterator_facade_default_category;
// Thrust's implementation of iterator_facade_default_category is slightly
// different from Boost's equivalent.
// Thrust does not check is_convertible<Reference, ValueParam> because Reference
// may not be a complete type at this point, and implementations of is_convertible
// typically require that both types be complete.
// Instead, it simply assumes that if is_convertible<Traversal, single_pass_traversal_tag>,
// then the category is input_iterator_tag
// this is the function for standard system iterators
template<typename Traversal, typename ValueParam, typename Reference>
struct iterator_facade_default_category_std :
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::forward_traversal_tag>::value,
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::random_access_traversal_tag>::value,
thrust::detail::identity_<std::random_access_iterator_tag>,
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::bidirectional_traversal_tag>::value,
thrust::detail::identity_<std::bidirectional_iterator_tag>,
thrust::detail::identity_<std::forward_iterator_tag>
>
>,
thrust::detail::eval_if< // XXX note we differ from Boost here
thrust::detail::is_convertible<Traversal, thrust::single_pass_traversal_tag>::value,
thrust::detail::identity_<std::input_iterator_tag>,
thrust::detail::identity_<Traversal>
>
>
{
}; // end iterator_facade_default_category_std
// this is the function for host system iterators
template<typename Traversal, typename ValueParam, typename Reference>
struct iterator_facade_default_category_host :
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::forward_traversal_tag>::value,
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::random_access_traversal_tag>::value,
thrust::detail::identity_<thrust::random_access_host_iterator_tag>,
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::bidirectional_traversal_tag>::value,
thrust::detail::identity_<thrust::bidirectional_host_iterator_tag>,
thrust::detail::identity_<thrust::forward_host_iterator_tag>
>
>,
thrust::detail::eval_if< // XXX note we differ from Boost here
thrust::detail::is_convertible<Traversal, thrust::single_pass_traversal_tag>::value,
thrust::detail::identity_<thrust::input_host_iterator_tag>,
thrust::detail::identity_<Traversal>
>
>
{
}; // end iterator_facade_default_category_host
// this is the function for device system iterators
template<typename Traversal, typename ValueParam, typename Reference>
struct iterator_facade_default_category_device :
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::forward_traversal_tag>::value,
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::random_access_traversal_tag>::value,
thrust::detail::identity_<thrust::random_access_device_iterator_tag>,
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::bidirectional_traversal_tag>::value,
thrust::detail::identity_<thrust::bidirectional_device_iterator_tag>,
thrust::detail::identity_<thrust::forward_device_iterator_tag>
>
>,
thrust::detail::eval_if<
thrust::detail::is_convertible<Traversal, thrust::single_pass_traversal_tag>::value, // XXX note we differ from Boost here
thrust::detail::identity_<thrust::input_device_iterator_tag>,
thrust::detail::identity_<Traversal>
>
>
{
}; // end iterator_facade_default_category_device
// this is the function for any system iterators
template<typename Traversal, typename ValueParam, typename Reference>
struct iterator_facade_default_category_any
{
typedef thrust::detail::iterator_category_with_system_and_traversal<
typename iterator_facade_default_category_std<Traversal, ValueParam, Reference>::type,
thrust::any_system_tag,
Traversal
> type;
}; // end iterator_facade_default_category_any
template<typename System, typename Traversal, typename ValueParam, typename Reference>
struct iterator_facade_default_category
// check for any system
: thrust::detail::eval_if<
thrust::detail::is_convertible<System, thrust::any_system_tag>::value,
iterator_facade_default_category_any<Traversal, ValueParam, Reference>,
// check for host system
thrust::detail::eval_if<
thrust::detail::is_convertible<System, thrust::host_system_tag>::value,
iterator_facade_default_category_host<Traversal, ValueParam, Reference>,
// check for device system
thrust::detail::eval_if<
thrust::detail::is_convertible<System, thrust::device_system_tag>::value,
iterator_facade_default_category_device<Traversal, ValueParam, Reference>,
// if we don't recognize the system, get a standard iterator category
// and combine it with System & Traversal
thrust::detail::identity_<
thrust::detail::iterator_category_with_system_and_traversal<
typename iterator_facade_default_category_std<Traversal, ValueParam, Reference>::type,
System,
Traversal
>
>
>
>
>
{};
template<typename System, typename Traversal, typename ValueParam, typename Reference>
struct iterator_facade_category_impl
{
typedef typename iterator_facade_default_category<
System,Traversal,ValueParam,Reference
>::type category;
// we must be able to deduce both Traversal & System from category
// otherwise, munge them all together
typedef typename thrust::detail::eval_if<
thrust::detail::and_<
thrust::detail::is_same<
Traversal,
typename thrust::detail::iterator_category_to_traversal<category>::type
>,
thrust::detail::is_same<
System,
typename thrust::detail::iterator_category_to_system<category>::type
>
>::value,
thrust::detail::identity_<category>,
thrust::detail::identity_<thrust::detail::iterator_category_with_system_and_traversal<category,System,Traversal> >
>::type type;
}; // end iterator_facade_category_impl
template<typename CategoryOrSystem,
typename CategoryOrTraversal,
typename ValueParam,
typename Reference>
struct iterator_facade_category
{
typedef typename
thrust::detail::eval_if<
thrust::detail::is_iterator_category<CategoryOrTraversal>::value,
thrust::detail::identity_<CategoryOrTraversal>, // categories are fine as-is
iterator_facade_category_impl<CategoryOrSystem, CategoryOrTraversal, ValueParam, Reference>
>::type type;
}; // end iterator_facade_category
} // end detail
THRUST_NAMESPACE_END
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