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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.
*/
/*! \file scan_by_key.h
* \brief Sequential implementation of scan_by_key functions.
*/
#pragma once
#include <thrust/detail/config.h>
#include <thrust/iterator/iterator_traits.h>
#include <thrust/detail/function.h>
#include <thrust/system/detail/sequential/execution_policy.h>
THRUST_NAMESPACE_BEGIN
namespace system
{
namespace detail
{
namespace sequential
{
__thrust_exec_check_disable__
template<typename DerivedPolicy,
typename InputIterator1,
typename InputIterator2,
typename OutputIterator,
typename BinaryPredicate,
typename BinaryFunction>
__host__ __device__
OutputIterator inclusive_scan_by_key(sequential::execution_policy<DerivedPolicy> &,
InputIterator1 first1,
InputIterator1 last1,
InputIterator2 first2,
OutputIterator result,
BinaryPredicate binary_pred,
BinaryFunction binary_op)
{
using KeyType = typename thrust::iterator_traits<InputIterator1>::value_type;
using ValueType = typename thrust::iterator_traits<InputIterator2>::value_type;
// wrap binary_op
thrust::detail::wrapped_function<
BinaryFunction,
ValueType
> wrapped_binary_op(binary_op);
if(first1 != last1)
{
KeyType prev_key = *first1;
ValueType prev_value = *first2;
*result = prev_value;
for(++first1, ++first2, ++result;
first1 != last1;
++first1, ++first2, ++result)
{
KeyType key = *first1;
if(binary_pred(prev_key, key))
*result = prev_value = wrapped_binary_op(prev_value,*first2);
else
*result = prev_value = *first2;
prev_key = key;
}
}
return result;
}
__thrust_exec_check_disable__
template<typename DerivedPolicy,
typename InputIterator1,
typename InputIterator2,
typename OutputIterator,
typename T,
typename BinaryPredicate,
typename BinaryFunction>
__host__ __device__
OutputIterator exclusive_scan_by_key(sequential::execution_policy<DerivedPolicy> &,
InputIterator1 first1,
InputIterator1 last1,
InputIterator2 first2,
OutputIterator result,
T init,
BinaryPredicate binary_pred,
BinaryFunction binary_op)
{
using KeyType = typename thrust::iterator_traits<InputIterator1>::value_type;
using ValueType = T;
if(first1 != last1)
{
KeyType temp_key = *first1;
ValueType temp_value = *first2;
ValueType next = init;
// first one is init
*result = next;
next = binary_op(next, temp_value);
for(++first1, ++first2, ++result;
first1 != last1;
++first1, ++first2, ++result)
{
KeyType key = *first1;
// use temp to permit in-place scans
temp_value = *first2;
if (!binary_pred(temp_key, key))
next = init; // reset sum
*result = next;
next = binary_op(next, temp_value);
temp_key = key;
}
}
return result;
}
} // end namespace sequential
} // end namespace detail
} // end namespace system
THRUST_NAMESPACE_END
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