001    /**
002     *
003     * Licensed to the Apache Software Foundation (ASF) under one or more
004     * contributor license agreements.  See the NOTICE file distributed with
005     * this work for additional information regarding copyright ownership.
006     * The ASF licenses this file to You under the Apache License, Version 2.0
007     * (the "License"); you may not use this file except in compliance with
008     * the License.  You may obtain a copy of the License at
009     *
010     * http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.camel.util;
019    
020    import org.apache.camel.Exchange;
021    import org.apache.camel.Expression;
022    
023    import java.util.Comparator;
024    
025    /**
026     * An implementation of {@link Comparator} which takes an {@link Expression} which is evaluated
027     * on each exchange to compare
028     *  
029     * @version $Revision: 1.1 $
030     */
031    public class ExpressionComparator<E extends Exchange> implements Comparator<E> {
032        private final Expression<E> expression;
033    
034        public ExpressionComparator(Expression<E> expression) {
035            this.expression = expression;
036        }
037    
038        public int compare(E e1, E e2) {
039            Object o1 = expression.evaluate(e1);
040            Object o2 = expression.evaluate(e2);
041            return ObjectHelper.compare(o1, o2);
042        }
043    }