unique_copy.h
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// -*- C++ -*-
// Copyright (C) 2007-2013 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License as published by the Free Software
// Foundation; either version 3, or (at your option) any later
// version.
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file parallel/unique_copy.h
* @brief Parallel implementations of std::unique_copy().
* This file is a GNU parallel extension to the Standard C++ Library.
*/
// Written by Robert Geisberger and Robin Dapp.
#ifndef _GLIBCXX_PARALLEL_UNIQUE_COPY_H
#define _GLIBCXX_PARALLEL_UNIQUE_COPY_H 1
#include <parallel/parallel.h>
#include <parallel/multiseq_selection.h>
namespace __gnu_parallel
{
/** @brief Parallel std::unique_copy(), w/__o explicit equality predicate.
* @param __first Begin iterator of input sequence.
* @param __last End iterator of input sequence.
* @param __result Begin iterator of result __sequence.
* @param __binary_pred Equality predicate.
* @return End iterator of result __sequence. */
template<typename _IIter,
class _OutputIterator,
class _BinaryPredicate>
_OutputIterator
__parallel_unique_copy(_IIter __first, _IIter __last,
_OutputIterator __result,
_BinaryPredicate __binary_pred)
{
_GLIBCXX_CALL(__last - __first)
typedef std::iterator_traits<_IIter> _TraitsType;
typedef typename _TraitsType::value_type _ValueType;
typedef typename _TraitsType::difference_type _DifferenceType;
_DifferenceType __size = __last - __first;
if (__size == 0)
return __result;
// Let the first thread process two parts.
_DifferenceType *__counter;
_DifferenceType *__borders;
_ThreadIndex __num_threads = __get_max_threads();
// First part contains at least one element.
# pragma omp parallel num_threads(__num_threads)
{
# pragma omp single
{
__num_threads = omp_get_num_threads();
__borders = new _DifferenceType[__num_threads + 2];
__equally_split(__size, __num_threads + 1, __borders);
__counter = new _DifferenceType[__num_threads + 1];
}
_ThreadIndex __iam = omp_get_thread_num();
_DifferenceType __begin, __end;
// Check for length without duplicates
// Needed for position in output
_DifferenceType __i = 0;
_OutputIterator __out = __result;
if (__iam == 0)
{
__begin = __borders[0] + 1; // == 1
__end = __borders[__iam + 1];
++__i;
*__out++ = *__first;
for (_IIter __iter = __first + __begin; __iter < __first + __end;
++__iter)
{
if (!__binary_pred(*__iter, *(__iter - 1)))
{
++__i;
*__out++ = *__iter;
}
}
}
else
{
__begin = __borders[__iam]; //one part
__end = __borders[__iam + 1];
for (_IIter __iter = __first + __begin; __iter < __first + __end;
++__iter)
{
if (!__binary_pred(*__iter, *(__iter - 1)))
++__i;
}
}
__counter[__iam] = __i;
// Last part still untouched.
_DifferenceType __begin_output;
# pragma omp barrier
// Store result in output on calculated positions.
__begin_output = 0;
if (__iam == 0)
{
for (_ThreadIndex __t = 0; __t < __num_threads; ++__t)
__begin_output += __counter[__t];
__i = 0;
_OutputIterator __iter_out = __result + __begin_output;
__begin = __borders[__num_threads];
__end = __size;
for (_IIter __iter = __first + __begin; __iter < __first + __end;
++__iter)
{
if (__iter == __first
|| !__binary_pred(*__iter, *(__iter - 1)))
{
++__i;
*__iter_out++ = *__iter;
}
}
__counter[__num_threads] = __i;
}
else
{
for (_ThreadIndex __t = 0; __t < __iam; __t++)
__begin_output += __counter[__t];
_OutputIterator __iter_out = __result + __begin_output;
for (_IIter __iter = __first + __begin; __iter < __first + __end;
++__iter)
{
if (!__binary_pred(*__iter, *(__iter - 1)))
*__iter_out++ = *__iter;
}
}
}
_DifferenceType __end_output = 0;
for (_ThreadIndex __t = 0; __t < __num_threads + 1; __t++)
__end_output += __counter[__t];
delete[] __borders;
return __result + __end_output;
}
/** @brief Parallel std::unique_copy(), without explicit equality predicate
* @param __first Begin iterator of input sequence.
* @param __last End iterator of input sequence.
* @param __result Begin iterator of result __sequence.
* @return End iterator of result __sequence. */
template<typename _IIter, class _OutputIterator>
inline _OutputIterator
__parallel_unique_copy(_IIter __first, _IIter __last,
_OutputIterator __result)
{
typedef typename std::iterator_traits<_IIter>::value_type
_ValueType;
return __parallel_unique_copy(__first, __last, __result,
std::equal_to<_ValueType>());
}
}//namespace __gnu_parallel
#endif /* _GLIBCXX_PARALLEL_UNIQUE_COPY_H */