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    import java.util.List;
025    
026    /**
027     * An implementation of {@link java.util.Comparator} which takes a list of
028     * {@link org.apache.camel.Expression} objects which is evaluated
029     * on each exchange to compare them
030     *
031     * @version $Revision: 1.1 $
032     */
033    public class ExpressionListComparator<E extends Exchange> implements Comparator<E> {
034        private final List<Expression<E>> expressions;
035    
036        public ExpressionListComparator(List<Expression<E>> expressions) {
037            this.expressions = expressions;
038        }
039    
040        public int compare(E e1, E e2) {
041            for (Expression<E> expression : expressions) {
042                Object o1 = expression.evaluate(e1);
043                Object o2 = expression.evaluate(e2);
044                int answer = ObjectHelper.compare(o1, o2);
045                if (answer != 0) {
046                    return answer;
047                }
048            }
049            return 0;
050        }
051    }