001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel.util;
018    
019    import java.util.Comparator;
020    
021    import org.apache.camel.Exchange;
022    import org.apache.camel.Expression;
023    
024    /**
025     * An implementation of {@link Comparator} which takes an {@link Expression} which is evaluated
026     * on each exchange to compare
027     *  
028     * @version $Revision: 3295 $
029     */
030    public class ExpressionComparator implements Comparator<Exchange> {
031        private final Expression expression;
032    
033        public ExpressionComparator(Expression expression) {
034            this.expression = expression;
035        }
036    
037        public int compare(Exchange e1, Exchange e2) {
038            Object o1 = expression.evaluate(e1, Object.class);
039            Object o2 = expression.evaluate(e2, Object.class);
040            return ObjectHelper.compare(o1, o2);
041        }
042    }