/*******************************************************************************
* Copyright (c) 2006 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
******************************************************************************/
package org.eclipse.ui.internal.services;
import java.util.Comparator;
import org.eclipse.ui.internal.util.Util;
/**
* <p>
* Compares two evaluation result caches ({@link IEvaluationResultCache}). The
* cache with the lowest source priority is considered "greater". In the event
* of a tie, other characteristics are checked.
* </p>
* <p>
* This class is only intended for use within the
* <code>org.eclipse.ui.workbench</code> plug-in.
* </p>
*
* @since 3.2
*
*/
public final class EvaluationResultCacheComparator implements Comparator {
public final int compare(final Object object1, final Object object2) {
if (Util.equals(object2, object1)) {
return 0;
}
final IEvaluationResultCache cache1 = (IEvaluationResultCache) object1;
final IEvaluationResultCache cache2 = (IEvaluationResultCache) object2;
int comparison;
/*
* Note: all of the comparisons are flipped intentionally. This allows
* those items with greater values to appear earlier when using an
* iterator.
*/
// if objects went to the trouble to implement Comparable
// we should use it ... this algorithm can accept a natural ordering
// that's not compatible with equals.
if (object1 instanceof Comparable && object2 instanceof Comparable) {
comparison = Util.compare((Comparable) object2,
(Comparable) object1);
if (comparison != 0) {
return comparison;
}
}
return Util.compareIdentity(cache2, cache1);
}
}