UnitPreferredFactionComparator.java from Magellan-Client at Krugle

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/*
 *  Copyright (C) 2000-2004 Roger Butenuth, Andreas Gampe,
 *                          Stefan Goetz, Sebastian Pappert,
 *                          Klaas Prause, Enno Rehling,
 *                          Sebastian Tusk, Ulrich Kuester,
 *                          Ilja Pavkovic
 *
 * This file is part of the Eressea Java Code Base, see the
 * file LICENSING for the licensing information applying to
 * this file.
 *
 */

package com.eressea.util.comparator;

import java.util.Comparator;

import com.eressea.EntityID;
import com.eressea.Unit;

/**
 * A comparator sorting units according to whether they belong to a specified faction or not.
 * 
 * <p>
 * Note: this comparator imposes orderings that are inconsistent with equals
 * </p>
 * 
 * <p>
 * This class allows to introduce sub-comparators in order to create a sorting hierarchy.
 * </p>
 * 
 * <p>
 * This comparator does not impose a strict ordering on the compared units, since either two units
 * may be of the same faction or the may be of different factions, where neither of them belongs
 * to the specified faction. In these cases the units remain "unsorted".
 * </p>
 * 
 * <p>
 * In order to have these units sorted, one sub-comparator for each of the two cases above my be
 * introduced, that may or, again, may not impose a strict order on the compared elements.
 * </p>
 */
public class UnitPreferredFactionComparator implements Comparator {
	protected Comparator preferredFactionSubCmp = null;
	protected Comparator otherFactionSubCmp = null;
	protected int factionID = 0;

	/**
	 * Creates a new <tt>UnitPreferredFactionComparator</tt> object with the specified
	 * sub-comparators and the specified faction id.
	 *
	 * @param preferredFactionSubComparator a <tt>Comparator</tt>     applied if both compared
	 * 		  units are in the preferred faction.
	 * @param otherFactionSubComparator a <tt>Comparator</tt>     applied if both compared units
	 * 		  are not in the preferred faction.
	 * @param fID TODO: DOCUMENT ME!
	 */
	public UnitPreferredFactionComparator(Comparator preferredFactionSubComparator,
										  Comparator otherFactionSubComparator, int fID) {
		preferredFactionSubCmp = preferredFactionSubComparator;
		otherFactionSubCmp = otherFactionSubComparator;
		factionID = fID;
	}

	/**
	 * Compares two units, where unit one is regarded less than unit two if unit one belongs to the
	 * preferred faction, whereas unit two does not. Cases of equality are handled by
	 * sub-comparators, if specified, or returned as such.
	 *
	 * @param o1 TODO: DOCUMENT ME!
	 * @param o2 TODO: DOCUMENT ME!
	 *
	 * @return -1 if o1 belongs to the preferred faction and o2 does not, 1 if o2 belongs to the
	 * 		   preferred faction and o1 does not. The return value in the other cases (both or
	 * 		   neither of them belong to the preferred faction) depends on the sub-comparators.
	 */
	public int compare(Object o1, Object o2) {
		int retVal = 0;
		int id1 = ((EntityID) ((Unit) o1).getFaction().getID()).intValue();
		int id2 = ((EntityID) ((Unit) o2).getFaction().getID()).intValue();

		if(id1 == factionID) {
			if(id2 == factionID) {
				if(preferredFactionSubCmp != null) {
					retVal = preferredFactionSubCmp.compare(o1, o2);
				} else {
					retVal = 0;
				}
			} else {
				retVal = -1;
			}
		} else {
			if(id2 == factionID) {
				retVal = 1;
			} else {
				if(otherFactionSubCmp != null) {
					retVal = otherFactionSubCmp.compare(o1, o2);
				} else {
					retVal = 0;
				}
			}
		}

		return retVal;
	}
}
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