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// -*- C++ -*-
// Copyright (C) 2007, 2008, 2009 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 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 Val>
bool
operator()(Val& 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.third = o(*i.first, *i.second);
return true;
}
};
/** @brief std::replace() selector. */
template<typename It, typename T>
struct replace_selector : public generic_for_each_selector<It>
{
/** @brief Value to replace with. */
const T& new_val;
/** @brief Constructor
* @param new_val Value to replace with. */
explicit
replace_selector(const T &new_val) : new_val(new_val) {}
/** @brief Functor execution.
* @param v Current value.
* @param i Iterator referencing object. */
bool
operator()(T& v, It i)
{
if (*i == v)
*i = new_val;
return true;
}
};
/** @brief std::replace() selector. */
template<typename It, typename Op, typename T>
struct replace_if_selector : public generic_for_each_selector<It>
{
/** @brief Value to replace with. */
const T& new_val;
/** @brief Constructor.
* @param new_val Value to replace with. */
explicit
replace_if_selector(const T &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 Val>
Diff
operator()(Val& 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 T>
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>
T
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;
}
};
// XXX move into type_traits?
/** @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 dummy_reduct
{
bool
operator()(bool /*x*/, bool /*y*/) const
{ return true; }
};
/** @brief Reduction for finding the maximum element, using a comparator. */
template<typename Comp, typename It>
struct min_element_reduct
{
Comp& comp;
explicit
min_element_reduct(Comp &c) : comp(c) { }
It
operator()(It x, It y)
{
if (comp(*x, *y))
return x;
else
return y;
}
};
/** @brief Reduction for finding the maximum element, using a comparator. */
template<typename Comp, typename It>
struct max_element_reduct
{
Comp& comp;
explicit
max_element_reduct(Comp& c) : comp(c) { }
It
operator()(It x, It y)
{
if (comp(*x, *y))
return y;
else
return 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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