net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/core/util/ToStringSorter.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2003 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11 package net.sourceforge.phpdt.internal.core.util;
  12
  13 /**
  14  * The SortOperation takes a collection of objects and returns a sorted
  15  * collection of these objects. The sorting of these objects is based on their
  16  * toString(). They are sorted in alphabetical order.
  17  */
  18 public class ToStringSorter {
  19         Object[] sortedObjects;
  20
  21         String[] sortedStrings;
  22
  23         /**
  24          * Returns true if stringTwo is 'greater than' stringOne This is the
  25          * 'ordering' method of the sort operation.
  26          */
  27         public boolean compare(String stringOne, String stringTwo) {
  28                 return stringOne.compareTo(stringTwo) < 0;
  29         }
  30
  31         /**
  32          * Sort the objects in sorted collection and return that collection.
  33          */
  34         private void quickSort(int left, int right) {
  35                 int originalLeft = left;
  36                 int originalRight = right;
  37                 int midIndex = (left + right) / 2;
  38                 String midToString = this.sortedStrings[midIndex];
  39
  40                 do {
  41                         while (compare(this.sortedStrings[left], midToString))
  42                                 left++;
  43                         while (compare(midToString, this.sortedStrings[right]))
  44                                 right--;
  45                         if (left <= right) {
  46                                 Object tmp = this.sortedObjects[left];
  47                                 this.sortedObjects[left] = this.sortedObjects[right];
  48                                 this.sortedObjects[right] = tmp;
  49                                 String tmpToString = this.sortedStrings[left];
  50                                 this.sortedStrings[left] = this.sortedStrings[right];
  51                                 this.sortedStrings[right] = tmpToString;
  52                                 left++;
  53                                 right--;
  54                         }
  55                 } while (left <= right);
  56
  57                 if (originalLeft < right)
  58                         quickSort(originalLeft, right);
  59                 if (left < originalRight)
  60                         quickSort(left, originalRight);
  61         }
  62
  63         /**
  64          * Return a new sorted collection from this unsorted collection. Sort using
  65          * quick sort.
  66          */
  67         public void sort(Object[] unSortedObjects, String[] unsortedStrings) {
  68                 int size = unSortedObjects.length;
  69                 this.sortedObjects = new Object[size];
  70                 this.sortedStrings = new String[size];
  71
  72                 // copy the array so can return a new sorted collection
  73                 System.arraycopy(unSortedObjects, 0, this.sortedObjects, 0, size);
  74                 System.arraycopy(unsortedStrings, 0, this.sortedStrings, 0, size);
  75                 if (size > 1)
  76                         quickSort(0, size - 1);
  77         }
  78 }