FixedListCompare.java

/*

   FixedListCompare.java

   Comparison interface for arlut.csd.Util sort classes.

   Created: 3 July 2001

   Module By: Jonathan Abbey, jonabbey@arlut.utexas.edu

   -----------------------------------------------------------------------

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   The University of Texas at Austin

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   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
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*/

package arlut.csd.Util;

import java.util.Comparator;
import java.util.Vector;

/*------------------------------------------------------------------------------
                                                                           class
                                                                FixedListCompare

------------------------------------------------------------------------------*/

/**
 * <p>This class implements the Comparator
 * interface, and provides a sort comparator that can sort things
 * according to a fixed ordering.  Items not in the original ordered
 * list will be placed after items in the original list, and in
 * alphabetical toString() order relative to each other.</p>
 *
 * @author Jonathan Abbey, jonabbey@arlut.utexas.edu, ARL:UT
 */

public class FixedListCompare implements Comparator {

  final static boolean debug = false;

  // ---

  private Vector items;
  private Comparator secondaryComparator;

  /**
   * @param items A list of items whose sort order we will impart on comparisons
   * @param secondaryComparator A Compare object that we will pass objects to
   * that are both missing from the items list.
   */

  public FixedListCompare(Vector items, Comparator secondaryComparator)
  {
    this.items = items;
    this.secondaryComparator = secondaryComparator;
  }

  /**
   * Comparator for arlut.csd.Util sort classes.  compare returns
   * -1 if a < b, 0 if a = b, and 1 if a > b in sort order.
   */

  public int compare(Object a, Object b)
  {
    if (debug)
      {
        System.err.println("Comparing a=" + a + "(" + a.getClass() + "), b=" + b + "(" + b.getClass() + "):");
      }

    int ai = items.indexOf(a);
    int bi = items.indexOf(b);

    if (ai == -1 && bi == -1)
      {
        if (debug)
          {
            System.err.println("\tCouldn't find either.");
          }

        if (secondaryComparator == null)
          {
            return a.toString().compareTo(b.toString());
          }
        else
          {
            return secondaryComparator.compare(a, b);
          }
      }
    else if (ai == -1)
      {
        if (debug)
          {
            System.err.println("\treturning 1");
          }

        return 1;
      }
    else if (bi == -1)
      {
        if (debug)
          {
            System.err.println("\treturning -1");
          }

        return -1;
      }
    else
      {
        if (ai == bi)
          {
            if (debug)
              {
                System.err.println("\treturning 0");
              }

            return 0;
          }

        if (ai < bi)
          {
            if (debug)
              {
                System.err.println("\treturning -1");
              }

            return -1;
          }

        // ai > bi

        if (debug)
          {
            System.err.println("\treturning 1");
          }

        return 1;
      }
  }
}