// Copyright (c) 1998-1999 Matra Datavision
// Copyright (c) 1999-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and / or modify it
// under the terms of the GNU Lesser General Public version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

// SortTools_QuickSort.gxx 
// cree le 04/11/91 par ASI
// Reference : Software Conponents with ADA, Grady Booch.

inline void Exchange(Item& Left, Item& Right)
{  
  Item Temp = Left;
  Left = Right;
  Right = Temp;
}

static void SortRecursive(Array& TheArray,
			  const Comparator& Comp,
			  const Standard_Integer Left, 
			  const Standard_Integer Right)
{
  Item Pivot;
  Standard_Integer Front, Back, Middle;
  
  if(Left < Right) {
    Middle = (Left + Right) / 2;
    if(Comp.IsLower(TheArray(Middle), TheArray(Left))) {
      Exchange(TheArray(Middle), TheArray(Left));
    }
    if(Comp.IsLower(TheArray(Right), TheArray(Left))) {
      Exchange(TheArray(Right), TheArray(Left));
    }
    if(Comp.IsLower(TheArray(Right), TheArray(Middle))) {
      Exchange(TheArray(Right), TheArray(Middle));
    }
    Pivot = TheArray(Middle);
    Exchange(TheArray(Middle), TheArray(Right - 1));
    Front = Left + 1;
    Back = Right - 1;
    if(Back != TheArray.Lower()) {
      Back = Back - 1;
    }
    for(;;) {
      while (Comp.IsLower(TheArray(Front), Pivot)) {
	Front = Front + 1;
      }
      while (Comp.IsLower(Pivot, TheArray(Back))) {
	Back = Back - 1;
      }
      if(Front <= Back) {
	if(Front == TheArray.Upper()) return;
	if(Back == TheArray.Lower()) return;  
	Exchange(TheArray(Front), TheArray(Back));
	Front = Front + 1;
	Back = Back - 1;
      }
      if(Front > Back) break;
    }
    SortRecursive(TheArray, Comp, Left, Back);
    SortRecursive(TheArray, Comp, Front, Right);
  }
}

void SortTools_QuickSort::Sort(Array& TheArray, 
			  const Comparator& Comp)
{
  SortRecursive(TheArray, Comp, TheArray.Lower(), TheArray.Upper()); 
}