// -*- 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/numeric
*
 * @brief Parallel STL function calls corresponding to stl_numeric.h.
 * The functions defined here mainly do case switches and
 * call the actual parallelized versions in other files.
 * Inlining policy: Functions that basically only contain one function call,
 * are declared inline.
 *  This file is a GNU parallel extension to the Standard C++ Library.
 */

// Written by Johannes Singler and Felix Putze.

#ifndef _GLIBCXX_PARALLEL_NUMERIC_H
#define _GLIBCXX_PARALLEL_NUMERIC_H 1

#include <numeric>
#include <functional>
#include <parallel/numericfwd.h>
#include <parallel/iterator.h>
#include <parallel/for_each.h>
#include <parallel/for_each_selectors.h>
#include <parallel/partial_sum.h>

namespace std
{
namespace __parallel
{
  // Sequential fallback.
  template<typename InputIterator, typename T>
    inline T
    accumulate(InputIterator begin, InputIterator end, T init, 
	       __gnu_parallel::sequential_tag)
    { return _GLIBCXX_STD_P::accumulate(begin, end, init); }

  template<typename InputIterator, typename T, typename BinaryOperation>
    inline T
    accumulate(InputIterator begin, InputIterator end, T init,
	       BinaryOperation binary_op, __gnu_parallel::sequential_tag)
    { return _GLIBCXX_STD_P::accumulate(begin, end, init, binary_op); }

  // Sequential fallback for input iterator case.
  template<typename InputIterator, typename T, typename IteratorTag>
    inline T
    accumulate_switch(InputIterator begin, InputIterator end,
		      T init, IteratorTag) 
    { return accumulate(begin, end, init, __gnu_parallel::sequential_tag()); }

  template<typename InputIterator, typename T, typename BinaryOperation,
	   typename IteratorTag>
    inline T
    accumulate_switch(InputIterator begin, InputIterator end, T init, 
		      BinaryOperation binary_op, IteratorTag)
    { return accumulate(begin, end, init, binary_op, 
			__gnu_parallel::sequential_tag()); }

  // Parallel algorithm for random access iterators.
  template<typename _RandomAccessIterator, typename T,
	   typename BinaryOperation>
    T
    accumulate_switch(_RandomAccessIterator begin, _RandomAccessIterator end, 
		      T init, BinaryOperation binary_op, 
		      random_access_iterator_tag, 
		      __gnu_parallel::_Parallelism parallelism_tag  
		      = __gnu_parallel::parallel_unbalanced)
    {
      if (_GLIBCXX_PARALLEL_CONDITION(
	    static_cast<__gnu_parallel::sequence_index_t>(end - begin)
	    >= __gnu_parallel::_Settings::get().accumulate_minimal_n
	    && __gnu_parallel::is_parallel(parallelism_tag)))
	{
	  T res = init;
	  __gnu_parallel::accumulate_selector<_RandomAccessIterator>
	    my_selector;
	  __gnu_parallel::
	    for_each_template_random_access_ed(begin, end,
					    __gnu_parallel::nothing(),
					    my_selector,
					    __gnu_parallel::
					    accumulate_binop_reduct
					    <BinaryOperation>(binary_op),
					    res, res, -1);
	  return res;
	}
      else
	return accumulate(begin, end, init, binary_op, 
			  __gnu_parallel::sequential_tag());
    }

  // Public interface.
  template<typename InputIterator, typename T>
    inline T
    accumulate(InputIterator begin, InputIterator end, T init, 
	       __gnu_parallel::_Parallelism parallelism_tag)
    {
      typedef std::iterator_traits<InputIterator> iterator_traits;
      typedef typename iterator_traits::value_type value_type;
      typedef typename iterator_traits::iterator_category iterator_category;

      return accumulate_switch(begin, end, init,
			       __gnu_parallel::plus<T, value_type>(),
			       iterator_category(), parallelism_tag);
    }

  template<typename InputIterator, typename T>
    inline T
    accumulate(InputIterator begin, InputIterator end, T init)
    {
      typedef std::iterator_traits<InputIterator> iterator_traits;
      typedef typename iterator_traits::value_type value_type;
      typedef typename iterator_traits::iterator_category iterator_category;

      return accumulate_switch(begin, end, init,
			       __gnu_parallel::plus<T, value_type>(),
			       iterator_category());
    }

  template<typename InputIterator, typename T, typename BinaryOperation>
    inline T
    accumulate(InputIterator begin, InputIterator end, T init, 
	       BinaryOperation binary_op, 
	       __gnu_parallel::_Parallelism parallelism_tag)
    {
      typedef iterator_traits<InputIterator> iterator_traits;
      typedef typename iterator_traits::iterator_category iterator_category;
      return accumulate_switch(begin, end, init, binary_op, 
			       iterator_category(), parallelism_tag);
    }

  template<typename InputIterator, typename T, typename BinaryOperation>
    inline T
    accumulate(InputIterator begin, InputIterator end, T init, 
	       BinaryOperation binary_op) 
    {
      typedef iterator_traits<InputIterator> iterator_traits;
      typedef typename iterator_traits::iterator_category iterator_category;
      return accumulate_switch(begin, end, init, binary_op, 
			       iterator_category());
    }


  // Sequential fallback.
  template<typename InputIterator1, typename InputIterator2, typename T>
    inline T
    inner_product(InputIterator1 first1, InputIterator1 last1, 
		  InputIterator2 first2, T init,
		  __gnu_parallel::sequential_tag)
    { return _GLIBCXX_STD_P::inner_product(first1, last1, first2, init); }

  template<typename InputIterator1, typename InputIterator2, typename T,
	   typename BinaryFunction1, typename BinaryFunction2>
    inline T
    inner_product(InputIterator1 first1, InputIterator1 last1, 
		  InputIterator2 first2, T init, BinaryFunction1 binary_op1, 
		  BinaryFunction2 binary_op2, __gnu_parallel::sequential_tag)
    { return _GLIBCXX_STD_P::inner_product(first1, last1, first2, init, 
					   binary_op1, binary_op2); }

  // Parallel algorithm for random access iterators.
  template<typename RandomAccessIterator1, typename RandomAccessIterator2,
	   typename T, typename BinaryFunction1, typename BinaryFunction2>
    T
    inner_product_switch(RandomAccessIterator1 first1,
			 RandomAccessIterator1 last1,
			 RandomAccessIterator2 first2, T init,
			 BinaryFunction1 binary_op1,
			 BinaryFunction2 binary_op2,
			 random_access_iterator_tag,
			 random_access_iterator_tag,
			 __gnu_parallel::_Parallelism parallelism_tag
			 = __gnu_parallel::parallel_unbalanced)
    {
      if (_GLIBCXX_PARALLEL_CONDITION((last1 - first1)
				      >= __gnu_parallel::_Settings::get().
				      accumulate_minimal_n
				      && __gnu_parallel::
				      is_parallel(parallelism_tag)))
	{
	  T res = init;
	  __gnu_parallel::
	    inner_product_selector<RandomAccessIterator1,
	    RandomAccessIterator2, T> my_selector(first1, first2);
	  __gnu_parallel::
	    for_each_template_random_access_ed(first1, last1, binary_op2,
					    my_selector, binary_op1,
					    res, res, -1);
	  return res;
	}
      else
	return inner_product(first1, last1, first2, init, 
			     __gnu_parallel::sequential_tag());
    }

  // No parallelism for input iterators.
  template<typename InputIterator1, typename InputIterator2, typename T,
	   typename BinaryFunction1, typename BinaryFunction2,
	   typename IteratorTag1, typename IteratorTag2>
    inline T
    inner_product_switch(InputIterator1 first1, InputIterator1 last1, 
			 InputIterator2 first2, T init, 
			 BinaryFunction1 binary_op1,
			 BinaryFunction2 binary_op2, 
			 IteratorTag1, IteratorTag2)
    { return inner_product(first1, last1, first2, init,
			   binary_op1, binary_op2,
			   __gnu_parallel::sequential_tag()); }

  template<typename InputIterator1, typename InputIterator2, typename T,
	   typename BinaryFunction1, typename BinaryFunction2>
    inline T
    inner_product(InputIterator1 first1, InputIterator1 last1, 
		  InputIterator2 first2, T init, BinaryFunction1 binary_op1, 
		  BinaryFunction2 binary_op2, 
		  __gnu_parallel::_Parallelism parallelism_tag)
    {
      typedef iterator_traits<InputIterator1> traits1_type;
      typedef typename traits1_type::iterator_category iterator1_category;

      typedef iterator_traits<InputIterator2> traits2_type;
      typedef typename traits2_type::iterator_category iterator2_category;

      return inner_product_switch(first1, last1, first2, init, binary_op1, 
				  binary_op2, iterator1_category(), 
				  iterator2_category(), parallelism_tag);
    }

  template<typename InputIterator1, typename InputIterator2, typename T,
	   typename BinaryFunction1, typename BinaryFunction2>
    inline T
    inner_product(InputIterator1 first1, InputIterator1 last1, 
		  InputIterator2 first2, T init, BinaryFunction1 binary_op1, 
		  BinaryFunction2 binary_op2)
    {
      typedef iterator_traits<InputIterator1> traits1_type;
      typedef typename traits1_type::iterator_category iterator1_category;

      typedef iterator_traits<InputIterator2> traits2_type;
      typedef typename traits2_type::iterator_category iterator2_category;

      return inner_product_switch(first1, last1, first2, init, binary_op1, 
				  binary_op2, iterator1_category(),
				  iterator2_category());
    }

  template<typename InputIterator1, typename InputIterator2, typename T>
    inline T
    inner_product(InputIterator1 first1, InputIterator1 last1, 
		  InputIterator2 first2, T init, 
		  __gnu_parallel::_Parallelism parallelism_tag)
    {
      typedef iterator_traits<InputIterator1> traits_type1;
      typedef typename traits_type1::value_type value_type1;
      typedef iterator_traits<InputIterator2> traits_type2;
      typedef typename traits_type2::value_type value_type2;

      typedef typename
	__gnu_parallel::multiplies<value_type1, value_type2>::result
        multiplies_result_type;
      return _GLIBCXX_STD_P::inner_product(first1, last1, first2, init,
                           __gnu_parallel::plus<T, multiplies_result_type>(),
                           __gnu_parallel::
			   multiplies<value_type1, value_type2>(),
                           parallelism_tag);
    }

  template<typename InputIterator1, typename InputIterator2, typename T>
    inline T
    inner_product(InputIterator1 first1, InputIterator1 last1, 
		  InputIterator2 first2, T init)
    {
      typedef iterator_traits<InputIterator1> traits_type1;
      typedef typename traits_type1::value_type value_type1;
      typedef iterator_traits<InputIterator2> traits_type2;
      typedef typename traits_type2::value_type value_type2;

      typedef typename
	__gnu_parallel::multiplies<value_type1, value_type2>::result
        multiplies_result_type;
      return _GLIBCXX_STD_P::inner_product(first1, last1, first2, init,
                           __gnu_parallel::plus<T, multiplies_result_type>(),
                           __gnu_parallel::
			   multiplies<value_type1, value_type2>());
    }

  // Sequential fallback.
  template<typename InputIterator, typename OutputIterator>
    inline OutputIterator
    partial_sum(InputIterator begin, InputIterator end, OutputIterator result,
		__gnu_parallel::sequential_tag)
    { return _GLIBCXX_STD_P::partial_sum(begin, end, result); }

  // Sequential fallback.
  template<typename InputIterator, typename OutputIterator,
	   typename BinaryOperation>
    inline OutputIterator
    partial_sum(InputIterator begin, InputIterator end, OutputIterator result,
		BinaryOperation bin_op, __gnu_parallel::sequential_tag)
    { return _GLIBCXX_STD_P::partial_sum(begin, end, result, bin_op); }

  // Sequential fallback for input iterator case.
  template<typename InputIterator, typename OutputIterator,
	   typename BinaryOperation, typename IteratorTag1,
	   typename IteratorTag2>
    inline OutputIterator
    partial_sum_switch(InputIterator begin, InputIterator end,
		       OutputIterator result, BinaryOperation bin_op,
		       IteratorTag1, IteratorTag2)
    { return _GLIBCXX_STD_P::partial_sum(begin, end, result, bin_op); }

  // Parallel algorithm for random access iterators.
  template<typename InputIterator, typename OutputIterator,
	   typename BinaryOperation>
    OutputIterator
    partial_sum_switch(InputIterator begin, InputIterator end,
		       OutputIterator result, BinaryOperation bin_op,
		       random_access_iterator_tag, random_access_iterator_tag)
    {
      if (_GLIBCXX_PARALLEL_CONDITION(
	    static_cast<__gnu_parallel::sequence_index_t>(end - begin)
	    >= __gnu_parallel::_Settings::get().partial_sum_minimal_n))
	return __gnu_parallel::parallel_partial_sum(begin, end,
						    result, bin_op);
      else
	return partial_sum(begin, end, result, bin_op,
			   __gnu_parallel::sequential_tag());
    }

  // Public interface.
  template<typename InputIterator, typename OutputIterator>
    inline OutputIterator
    partial_sum(InputIterator begin, InputIterator end, OutputIterator result)
    {
      typedef typename iterator_traits<InputIterator>::value_type value_type;
      return _GLIBCXX_STD_P::partial_sum(begin, end, result,
                                         std::plus<value_type>());
    }

  // Public interface
  template<typename InputIterator, typename OutputIterator,
	   typename BinaryOperation>
    inline OutputIterator
    partial_sum(InputIterator begin, InputIterator end, OutputIterator result,
		BinaryOperation binary_op)
    {
      typedef iterator_traits<InputIterator> traitsi_type;
      typedef typename traitsi_type::iterator_category iteratori_category;

      typedef iterator_traits<OutputIterator> traitso_type;
      typedef typename traitso_type::iterator_category iteratoro_category;

      return partial_sum_switch(begin, end, result, binary_op,
				iteratori_category(), iteratoro_category());
    }

  // Sequential fallback.
  template<typename InputIterator, typename OutputIterator>
    inline OutputIterator
    adjacent_difference(InputIterator begin, InputIterator end,
			OutputIterator result, __gnu_parallel::sequential_tag)
    { return _GLIBCXX_STD_P::adjacent_difference(begin, end, result); }

  // Sequential fallback.
  template<typename InputIterator, typename OutputIterator,
	   typename BinaryOperation>
    inline OutputIterator
    adjacent_difference(InputIterator begin, InputIterator end,
			OutputIterator result, BinaryOperation bin_op,
			__gnu_parallel::sequential_tag)
    { return _GLIBCXX_STD_P::adjacent_difference(begin, end, result, bin_op); }

  // Sequential fallback for input iterator case.
  template<typename InputIterator, typename OutputIterator,
	   typename BinaryOperation, typename IteratorTag1,
	   typename IteratorTag2>
    inline OutputIterator
    adjacent_difference_switch(InputIterator begin, InputIterator end,
			       OutputIterator result, BinaryOperation bin_op,
			     IteratorTag1, IteratorTag2)
    { return adjacent_difference(begin, end, result, bin_op,  
				 __gnu_parallel::sequential_tag()); }

  // Parallel algorithm for random access iterators.
  template<typename InputIterator, typename OutputIterator,
	   typename BinaryOperation>
    OutputIterator
    adjacent_difference_switch(InputIterator begin, InputIterator end,
			       OutputIterator result, BinaryOperation bin_op,
			       random_access_iterator_tag, 
			       random_access_iterator_tag,
			       __gnu_parallel::_Parallelism parallelism_tag
			       = __gnu_parallel::parallel_balanced)
    {
      if (_GLIBCXX_PARALLEL_CONDITION(
	    static_cast<__gnu_parallel::sequence_index_t>(end - begin)
	    >= __gnu_parallel::_Settings::get().adjacent_difference_minimal_n
	    && __gnu_parallel::is_parallel(parallelism_tag)))
	{
	  bool dummy = true;
	  typedef __gnu_parallel::iterator_pair<InputIterator, OutputIterator,
	    random_access_iterator_tag> ip;
	  *result = *begin;
	  ip begin_pair(begin + 1, result + 1),
	    end_pair(end, result + (end - begin));
	  __gnu_parallel::adjacent_difference_selector<ip> functionality;
	  __gnu_parallel::
	    for_each_template_random_access_ed(begin_pair, end_pair, bin_op,
					    functionality,
					    __gnu_parallel::dummy_reduct(),
					    dummy, dummy, -1);
	  return functionality.finish_iterator;
	}
      else
	return adjacent_difference(begin, end, result, bin_op, 
				   __gnu_parallel::sequential_tag());
    }

  // Public interface.
  template<typename InputIterator, typename OutputIterator>
    inline OutputIterator
    adjacent_difference(InputIterator begin, InputIterator end,
			OutputIterator result,
			__gnu_parallel::_Parallelism parallelism_tag)
    {
      typedef iterator_traits<InputIterator> traits_type;
      typedef typename traits_type::value_type value_type;
      return adjacent_difference(begin, end, result, std::minus<value_type>(),
				 parallelism_tag);
    }

  template<typename InputIterator, typename OutputIterator>
    inline OutputIterator
    adjacent_difference(InputIterator begin, InputIterator end,
			OutputIterator result)
    {
      typedef iterator_traits<InputIterator> traits_type;
      typedef typename traits_type::value_type value_type;
      return adjacent_difference(begin, end, result, std::minus<value_type>());
    }

  template<typename InputIterator, typename OutputIterator,
	   typename BinaryOperation>
    inline OutputIterator
    adjacent_difference(InputIterator begin, InputIterator end,
			OutputIterator result, BinaryOperation binary_op,
			__gnu_parallel::_Parallelism parallelism_tag)
    {
      typedef iterator_traits<InputIterator> traitsi_type;
      typedef typename traitsi_type::iterator_category iteratori_category;

      typedef iterator_traits<OutputIterator> traitso_type;
      typedef typename traitso_type::iterator_category iteratoro_category;

      return adjacent_difference_switch(begin, end, result, binary_op,
					iteratori_category(), 
					iteratoro_category(), parallelism_tag);
    }

  template<typename InputIterator, typename OutputIterator,
	   typename BinaryOperation>
    inline OutputIterator
    adjacent_difference(InputIterator begin, InputIterator end,
			OutputIterator result, BinaryOperation binary_op)
    {
      typedef iterator_traits<InputIterator> traitsi_type;
      typedef typename traitsi_type::iterator_category iteratori_category;

      typedef iterator_traits<OutputIterator> traitso_type;
      typedef typename traitso_type::iterator_category iteratoro_category;

      return adjacent_difference_switch(begin, end, result, binary_op,
					iteratori_category(), 
					iteratoro_category());
    }
} // end namespace
} // end namespace

#endif /* _GLIBCXX_NUMERIC_H */
