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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/pair.h>
#include <thrust/iterator/iterator_traits.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 OutputIterator1,
typename OutputIterator2,
typename BinaryPredicate,
typename BinaryFunction>
__host__ __device__
thrust::pair<OutputIterator1,OutputIterator2>
reduce_by_key(sequential::execution_policy<DerivedPolicy> &,
InputIterator1 keys_first,
InputIterator1 keys_last,
InputIterator2 values_first,
OutputIterator1 keys_output,
OutputIterator2 values_output,
BinaryPredicate binary_pred,
BinaryFunction binary_op)
{
typedef typename thrust::iterator_traits<InputIterator1>::value_type InputKeyType;
typedef typename thrust::iterator_traits<InputIterator2>::value_type InputValueType;
// Use the input iterator's value type per https://wg21.link/P0571
using TemporaryType = typename thrust::iterator_value<InputIterator2>::type;
if(keys_first != keys_last)
{
InputKeyType temp_key = *keys_first;
TemporaryType temp_value = *values_first;
for(++keys_first, ++values_first;
keys_first != keys_last;
++keys_first, ++values_first)
{
InputKeyType key = *keys_first;
InputValueType value = *values_first;
if(binary_pred(temp_key, key))
{
temp_value = binary_op(temp_value, value);
}
else
{
*keys_output = temp_key;
*values_output = temp_value;
++keys_output;
++values_output;
temp_key = key;
temp_value = value;
}
}
*keys_output = temp_key;
*values_output = temp_value;
++keys_output;
++values_output;
}
return thrust::make_pair(keys_output, values_output);
}
} // end namespace sequential
} // end namespace detail
} // end namespace system
THRUST_NAMESPACE_END
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