/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.collections.comparators;
import java.util.Comparator;
import org.apache.commons.collections.Transformer;
/**
* Decorates another Comparator with transformation behavior. That is, the
* return value from the transform operation will be passed to the decorated
* {@link Comparator#compare(Object,Object) compare} method.
*
* @since Commons Collections 2.0 (?)
* @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
*
* @see org.apache.commons.collections.Transformer
* @see org.apache.commons.collections.comparators.ComparableComparator
*/
public class TransformingComparator implements Comparator {
/** The decorated comparator. */
protected Comparator decorated;
/** The transformer being used. */
protected Transformer transformer;
//-----------------------------------------------------------------------
/**
* Constructs an instance with the given Transformer and a
* {@link ComparableComparator ComparableComparator}.
*
* @param transformer what will transform the arguments to <code>compare</code>
*/
public TransformingComparator(Transformer transformer) {
this(transformer, new ComparableComparator());
}
/**
* Constructs an instance with the given Transformer and Comparator.
*
* @param transformer what will transform the arguments to <code>compare</code>
* @param decorated the decorated Comparator
*/
public TransformingComparator(Transformer transformer, Comparator decorated) {
this.decorated = decorated;
this.transformer = transformer;
}
//-----------------------------------------------------------------------
/**
* Returns the result of comparing the values from the transform operation.
*
* @param obj1 the first object to transform then compare
* @param obj2 the second object to transform then compare
* @return negative if obj1 is less, positive if greater, zero if equal
*/
public int compare(Object obj1, Object obj2) {
Object value1 = this.transformer.transform(obj1);
Object value2 = this.transformer.transform(obj2);
return this.decorated.compare(value1, value2);
}
}