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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/iterator/transform_iterator.h>
#include <thrust/iterator/zip_iterator.h>
#include <thrust/iterator/counting_iterator.h>
#include <thrust/tuple.h>
#include <thrust/functional.h>
THRUST_NAMESPACE_BEGIN
namespace detail
{
template<typename RandomAccessIterator,
typename BinaryPredicate = thrust::equal_to<typename thrust::iterator_value<RandomAccessIterator>::type>,
typename ValueType = bool,
typename IndexType = typename thrust::iterator_difference<RandomAccessIterator>::type>
class head_flags_with_init
{
typedef typename thrust::iterator_value<RandomAccessIterator>::type init_type;
// XXX WAR cudafe issue
//private:
public:
struct head_flag_functor
{
BinaryPredicate binary_pred; // this must be the first member for performance reasons
init_type init;
IndexType n;
typedef ValueType result_type;
__host__ __device__
head_flag_functor(init_type init, IndexType n)
: binary_pred(), init(init), n(n)
{}
__host__ __device__
head_flag_functor(init_type init, IndexType n, BinaryPredicate binary_pred)
: binary_pred(binary_pred), init(init), n(n)
{}
template<typename Tuple>
__host__ __device__ __thrust_forceinline__
result_type operator()(const Tuple &t)
{
const IndexType i = thrust::get<0>(t);
if(i == 0)
{
return !binary_pred(init, thrust::get<1>(t));
}
return !binary_pred(thrust::get<1>(t), thrust::get<2>(t));
}
};
typedef thrust::counting_iterator<IndexType> counting_iterator;
public:
typedef thrust::transform_iterator<
head_flag_functor,
thrust::zip_iterator<thrust::tuple<counting_iterator,RandomAccessIterator,RandomAccessIterator> >
> iterator;
__thrust_exec_check_disable__
__host__ __device__
head_flags_with_init(RandomAccessIterator first, RandomAccessIterator last, init_type init)
: m_begin(thrust::make_transform_iterator(thrust::make_zip_iterator(thrust::make_tuple(thrust::counting_iterator<IndexType>(0), first, first - 1)),
head_flag_functor(init, last - first))),
m_end(m_begin + (last - first))
{}
__thrust_exec_check_disable__
__host__ __device__
head_flags_with_init(RandomAccessIterator first, RandomAccessIterator last, init_type init, BinaryPredicate binary_pred)
: m_begin(thrust::make_transform_iterator(thrust::make_zip_iterator(thrust::make_tuple(thrust::counting_iterator<IndexType>(0), first, first - 1)),
head_flag_functor(init, last - first, binary_pred))),
m_end(m_begin + (last - first))
{}
__host__ __device__
iterator begin() const
{
return m_begin;
}
__host__ __device__
iterator end() const
{
return m_end;
}
template<typename OtherIndex>
__host__ __device__
typename iterator::reference operator[](OtherIndex i)
{
return *(begin() + i);
}
private:
iterator m_begin, m_end;
};
template<typename RandomAccessIterator,
typename BinaryPredicate = thrust::equal_to<typename thrust::iterator_value<RandomAccessIterator>::type>,
typename ValueType = bool,
typename IndexType = typename thrust::iterator_difference<RandomAccessIterator>::type>
class head_flags
{
// XXX WAR cudafe issue
//private:
public:
struct head_flag_functor
{
BinaryPredicate binary_pred; // this must be the first member for performance reasons
IndexType n;
typedef ValueType result_type;
__host__ __device__
head_flag_functor(IndexType n)
: binary_pred(), n(n)
{}
__host__ __device__
head_flag_functor(IndexType n, BinaryPredicate binary_pred)
: binary_pred(binary_pred), n(n)
{}
template<typename Tuple>
__host__ __device__ __thrust_forceinline__
result_type operator()(const Tuple &t)
{
const IndexType i = thrust::get<0>(t);
// note that we do not dereference the tuple's 2nd element when i <= 0
// and therefore do not dereference a bad location at the boundary
return (i == 0 || !binary_pred(thrust::get<1>(t), thrust::get<2>(t)));
}
};
typedef thrust::counting_iterator<IndexType> counting_iterator;
public:
typedef thrust::transform_iterator<
head_flag_functor,
thrust::zip_iterator<thrust::tuple<counting_iterator,RandomAccessIterator,RandomAccessIterator> >
> iterator;
__host__ __device__
head_flags(RandomAccessIterator first, RandomAccessIterator last)
: m_begin(thrust::make_transform_iterator(thrust::make_zip_iterator(thrust::make_tuple(thrust::counting_iterator<IndexType>(0), first, first - 1)),
head_flag_functor(last - first))),
m_end(m_begin + (last - first))
{}
__host__ __device__
head_flags(RandomAccessIterator first, RandomAccessIterator last, BinaryPredicate binary_pred)
: m_begin(thrust::make_transform_iterator(thrust::make_zip_iterator(thrust::make_tuple(thrust::counting_iterator<IndexType>(0), first, first - 1)),
head_flag_functor(last - first, binary_pred))),
m_end(m_begin + (last - first))
{}
__host__ __device__
iterator begin() const
{
return m_begin;
}
__host__ __device__
iterator end() const
{
return m_end;
}
template<typename OtherIndex>
__host__ __device__
typename iterator::reference operator[](OtherIndex i)
{
return *(begin() + i);
}
private:
iterator m_begin, m_end;
};
template<typename RandomAccessIterator, typename BinaryPredicate>
__host__ __device__
head_flags<RandomAccessIterator, BinaryPredicate>
make_head_flags(RandomAccessIterator first, RandomAccessIterator last, BinaryPredicate binary_pred)
{
return head_flags<RandomAccessIterator, BinaryPredicate>(first, last, binary_pred);
}
template<typename RandomAccessIterator>
__host__ __device__
head_flags<RandomAccessIterator>
make_head_flags(RandomAccessIterator first, RandomAccessIterator last)
{
return head_flags<RandomAccessIterator>(first, last);
}
} // end detail
THRUST_NAMESPACE_END
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