Preview: for_each_selectors.h
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//opt/rh/gcc-toolset-14/root/usr/include/c++/14/parallel/for_each_selectors.h
// -*- C++ -*-
// Copyright (C) 2007-2024 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/for_each_selectors.h
* @brief Functors representing different tasks to be plugged into the
* generic parallelization methods for embarrassingly parallel functions.
* This file is a GNU parallel extension to the Standard C++ Library.
*/
// Written by Felix Putze.
#ifndef _GLIBCXX_PARALLEL_FOR_EACH_SELECTORS_H
#define _GLIBCXX_PARALLEL_FOR_EACH_SELECTORS_H 1
#include <parallel/basic_iterator.h>
namespace __gnu_parallel
{
/** @brief Generic __selector for embarrassingly parallel functions. */
template<typename _It>
struct __generic_for_each_selector
{
/** @brief _Iterator on last element processed; needed for some
* algorithms (e. g. std::transform()).
*/
_It _M_finish_iterator;
};
/** @brief std::for_each() selector. */
template<typename _It>
struct __for_each_selector : public __generic_for_each_selector<_It>
{
/** @brief Functor execution.
* @param __o Operator.
* @param __i iterator referencing object. */
template<typename _Op>
bool
operator()(_Op& __o, _It __i)
{
__o(*__i);
return true;
}
};
/** @brief std::generate() selector. */
template<typename _It>
struct __generate_selector : public __generic_for_each_selector<_It>
{
/** @brief Functor execution.
* @param __o Operator.
* @param __i iterator referencing object. */
template<typename _Op>
bool
operator()(_Op& __o, _It __i)
{
*__i = __o();
return true;
}
};
/** @brief std::fill() selector. */
template<typename _It>
struct __fill_selector : public __generic_for_each_selector<_It>
{
/** @brief Functor execution.
* @param __v Current value.
* @param __i iterator referencing object. */
template<typename _ValueType>
bool
operator()(_ValueType& __v, _It __i)
{
*__i = __v;
return true;
}
};
/** @brief std::transform() __selector, one input sequence variant. */
template<typename _It>
struct __transform1_selector : public __generic_for_each_selector<_It>
{
/** @brief Functor execution.
* @param __o Operator.
* @param __i iterator referencing object. */
template<typename _Op>
bool
operator()(_Op& __o, _It __i)
{
*__i.second = __o(*__i.first);
return true;
}
};
/** @brief std::transform() __selector, two input sequences variant. */
template<typename _It>
struct __transform2_selector : public __generic_for_each_selector<_It>
{
/** @brief Functor execution.
* @param __o Operator.
* @param __i iterator referencing object. */
template<typename _Op>
bool
operator()(_Op& __o, _It __i)
{
*__i._M_third = __o(*__i._M_first, *__i._M_second);
return true;
}
};
/** @brief std::replace() selector. */
template<typename _It, typename _Tp>
struct __replace_selector : public __generic_for_each_selector<_It>
{
/** @brief Value to replace with. */
const _Tp& __new_val;
/** @brief Constructor
* @param __new_val Value to replace with. */
explicit
__replace_selector(const _Tp &__new_val) : __new_val(__new_val) {}
/** @brief Functor execution.
* @param __v Current value.
* @param __i iterator referencing object. */
bool
operator()(_Tp& __v, _It __i)
{
if (*__i == __v)
*__i = __new_val;
return true;
}
};
/** @brief std::replace() selector. */
template<typename _It, typename _Op, typename _Tp>
struct __replace_if_selector : public __generic_for_each_selector<_It>
{
/** @brief Value to replace with. */
const _Tp& __new_val;
/** @brief Constructor.
* @param __new_val Value to replace with. */
explicit
__replace_if_selector(const _Tp &__new_val) : __new_val(__new_val) { }
/** @brief Functor execution.
* @param __o Operator.
* @param __i iterator referencing object. */
bool
operator()(_Op& __o, _It __i)
{
if (__o(*__i))
*__i = __new_val;
return true;
}
};
/** @brief std::count() selector. */
template<typename _It, typename _Diff>
struct __count_selector : public __generic_for_each_selector<_It>
{
/** @brief Functor execution.
* @param __v Current value.
* @param __i iterator referencing object.
* @return 1 if count, 0 if does not count. */
template<typename _ValueType>
_Diff
operator()(_ValueType& __v, _It __i)
{ return (__v == *__i) ? 1 : 0; }
};
/** @brief std::count_if () selector. */
template<typename _It, typename _Diff>
struct __count_if_selector : public __generic_for_each_selector<_It>
{
/** @brief Functor execution.
* @param __o Operator.
* @param __i iterator referencing object.
* @return 1 if count, 0 if does not count. */
template<typename _Op>
_Diff
operator()(_Op& __o, _It __i)
{ return (__o(*__i)) ? 1 : 0; }
};
/** @brief std::accumulate() selector. */
template<typename _It>
struct __accumulate_selector : public __generic_for_each_selector<_It>
{
/** @brief Functor execution.
* @param __o Operator (unused).
* @param __i iterator referencing object.
* @return The current value. */
template<typename _Op>
typename std::iterator_traits<_It>::value_type
operator()(_Op __o, _It __i)
{ return *__i; }
};
/** @brief std::inner_product() selector. */
template<typename _It, typename _It2, typename _Tp>
struct __inner_product_selector : public __generic_for_each_selector<_It>
{
/** @brief Begin iterator of first sequence. */
_It __begin1_iterator;
/** @brief Begin iterator of second sequence. */
_It2 __begin2_iterator;
/** @brief Constructor.
* @param __b1 Begin iterator of first sequence.
* @param __b2 Begin iterator of second sequence. */
explicit
__inner_product_selector(_It __b1, _It2 __b2)
: __begin1_iterator(__b1), __begin2_iterator(__b2) { }
/** @brief Functor execution.
* @param __mult Multiplication functor.
* @param __current iterator referencing object.
* @return Inner product elemental __result. */
template<typename _Op>
_Tp
operator()(_Op __mult, _It __current)
{
typename std::iterator_traits<_It>::difference_type __position
= __current - __begin1_iterator;
return __mult(*__current, *(__begin2_iterator + __position));
}
};
/** @brief Selector that just returns the passed iterator. */
template<typename _It>
struct __identity_selector : public __generic_for_each_selector<_It>
{
/** @brief Functor execution.
* @param __o Operator (unused).
* @param __i iterator referencing object.
* @return Passed iterator. */
template<typename _Op>
_It
operator()(_Op __o, _It __i)
{ return __i; }
};
/** @brief Selector that returns the difference between two adjacent
* __elements.
*/
template<typename _It>
struct __adjacent_difference_selector
: public __generic_for_each_selector<_It>
{
template<typename _Op>
bool
operator()(_Op& __o, _It __i)
{
typename _It::first_type __go_back_one = __i.first;
--__go_back_one;
*__i.second = __o(*__i.first, *__go_back_one);
return true;
}
};
/** @brief Functor doing nothing
*
* For some __reduction tasks (this is not a function object, but is
* passed as __selector __dummy parameter.
*/
struct _Nothing
{
/** @brief Functor execution.
* @param __i iterator referencing object. */
template<typename _It>
void
operator()(_It __i) { }
};
/** @brief Reduction function doing nothing. */
struct _DummyReduct
{
bool
operator()(bool, bool) const
{ return true; }
};
/** @brief Reduction for finding the maximum element, using a comparator. */
template<typename _Compare, typename _It>
struct __min_element_reduct
{
_Compare& __comp;
explicit
__min_element_reduct(_Compare &__c) : __comp(__c) { }
_It
operator()(_It __x, _It __y)
{ return (__comp(*__x, *__y)) ? __x : __y; }
};
/** @brief Reduction for finding the maximum element, using a comparator. */
template<typename _Compare, typename _It>
struct __max_element_reduct
{
_Compare& __comp;
explicit
__max_element_reduct(_Compare& __c) : __comp(__c) { }
_It
operator()(_It __x, _It __y)
{ return (__comp(*__x, *__y)) ? __y : __x; }
};
/** @brief General reduction, using a binary operator. */
template<typename _BinOp>
struct __accumulate_binop_reduct
{
_BinOp& __binop;
explicit
__accumulate_binop_reduct(_BinOp& __b) : __binop(__b) { }
template<typename _Result, typename _Addend>
_Result
operator()(const _Result& __x, const _Addend& __y)
{ return __binop(__x, __y); }
};
}
#endif /* _GLIBCXX_PARALLEL_FOR_EACH_SELECTORS_H */
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