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    import java.util.List;
021    
022    import org.apache.camel.Exchange;
023    import org.apache.camel.Expression;
024    
025    /**
026     * An implementation of {@link java.util.Comparator} which takes a list of
027     * {@link org.apache.camel.Expression} objects which is evaluated
028     * on each exchange to compare them
029     *
030     * @version 
031     */
032    public class ExpressionListComparator implements Comparator<Exchange> {
033        private final List<Expression> expressions;
034    
035        public ExpressionListComparator(List<Expression> expressions) {
036            this.expressions = expressions;
037        }
038    
039        public int compare(Exchange e1, Exchange e2) {
040            for (Expression expression : expressions) {
041                Object o1 = expression.evaluate(e1, Object.class);
042                Object o2 = expression.evaluate(e2, Object.class);
043                int answer = ObjectHelper.compare(o1, o2);
044                if (answer != 0) {
045                    return answer;
046                }
047            }
048            return 0;
049        }
050    }