Saf/Algo/Sort/QuickSort.h

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/*
    This file is part of Simple Application Framework (Saf) library.
    Copyright (C) 2010 - 2012 Ondrej Danek <ondrej.danek@gmail.com>

    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 of the License, or
    (at your option) any later version.

    Saf 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.

    You should have received a copy of the GNU General Public License
    along with Simple Application Framework library. If not, 
    see <http://www.gnu.org/licenses/>.
*/

#ifndef SAF_ALGO_SORT_QUICKSORT_H
#define SAF_ALGO_SORT_QUICKSORT_H

#include "../../Type.h"
#include "../Predicate.h"
#include "../../Collection/Pair.h"
#include "SortInternal.h"

namespace Saf
{
    namespace Algo
    {        
        namespace Sort
        {
            template <class RanIter, class Pred>
            void QuickSort(RanIter begin, RanIter end, Pred pred)
            {
                while (Diff(end - begin) > 1)
                {
                    // Find pivot and partition the sequence into two parts
                    Collection::Pair<RanIter,RanIter> cut;
                    cut = Internal::AlgoSort::PartitionSmart(begin, end, pred);

                    // Sort the shorter part first to achieve log(n) space complexity
                    if (Diff(cut.m_first - begin) > Diff(end - cut.m_second))
                    {
                        QuickSort(cut.m_second, end, pred);
                        end = cut.m_first;
                    }
                    else
                    {
                        QuickSort(begin, cut.m_first, pred);
                        begin = cut.m_second;
                    }
                }
            }

            template <class RanIter>
            void QuickSort(RanIter begin, RanIter end)
            {
                Predicate::Less<typename Type::IteratorTraits<RanIter>::ValType> pred;
                QuickSort(begin, end, pred);
            }
        }
    }
}

#endif