package org.freehep.swing.treetable.test;
/**
* An implementation of MergeSort, needs to be subclassed to compare the terms.
*
* @author Scott Violet
*/
public abstract class MergeSort extends Object
{
protected Object toSort[];
protected Object swapSpace[];
public void sort(Object array[])
{
if(array != null && array.length > 1)
{
int maxLength;
maxLength = array.length;
swapSpace = new Object[maxLength];
toSort = array;
this.mergeSort(0, maxLength - 1);
swapSpace = null;
toSort = null;
}
}
public abstract int compareElementsAt(int beginLoc, int endLoc);
protected void mergeSort(int begin, int end)
{
if(begin != end)
{
int mid;
mid = (begin + end) / 2;
this.mergeSort(begin, mid);
this.mergeSort(mid + 1, end);
this.merge(begin, mid, end);
}
}
protected void merge(int begin, int middle, int end)
{
int firstHalf, secondHalf, count;
firstHalf = count = begin;
secondHalf = middle + 1;
while((firstHalf <= middle) && (secondHalf <= end))
{
if(this.compareElementsAt(secondHalf, firstHalf) < 0)
swapSpace[count++] = toSort[secondHalf++];
else
swapSpace[count++] = toSort[firstHalf++];
}
if(firstHalf <= middle)
{
while(firstHalf <= middle)
swapSpace[count++] = toSort[firstHalf++];
}
else
{
while(secondHalf <= end)
swapSpace[count++] = toSort[secondHalf++];
}
for(count = begin;count <= end;count++)
toSort[count] = swapSpace[count];
}
}