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.processor.resequencer;
018    
019    import org.apache.camel.Exchange;
020    import org.apache.camel.Expression;
021    
022    /**
023     * Compares elements of an {@link Exchange} sequence by comparing
024     * <code>long</code> values returned by this comparator's
025     * <code>expression</code>.
026     * 
027     * @version 
028     */
029    public class DefaultExchangeComparator implements ExpressionResultComparator {
030    
031        private Expression expression;
032    
033        @Override
034        public void setExpression(Expression expression) {
035            this.expression = expression;
036        }
037    
038        @Override
039        public boolean predecessor(Exchange o1, Exchange o2) {
040            long n1 = getSequenceNumber(o1);
041            long n2 = getSequenceNumber(o2);
042            return n1 == (n2 - 1L);
043        }
044    
045        @Override
046        public boolean successor(Exchange o1, Exchange o2) {
047            long n1 = getSequenceNumber(o1);
048            long n2 = getSequenceNumber(o2);
049            return n2 == (n1 - 1L);
050        }
051    
052        @Override
053        public int compare(Exchange o1, Exchange o2) {
054            Long n1 = getSequenceNumber(o1);
055            Long n2 = getSequenceNumber(o2);
056            return n1.compareTo(n2);
057        }
058    
059        private Long getSequenceNumber(Exchange exchange) {
060            return expression.evaluate(exchange, Long.class);
061        }
062    
063        @Override
064        public boolean isValid(Exchange exchange) {
065            Long num = null;
066            try {
067                num = expression.evaluate(exchange, Long.class);
068            } catch (Exception e) {
069                // ignore
070            }
071            return num != null;
072        }
073    
074        @Override
075        public String toString() {
076            return "Comparator[" + expression + "]";
077        }
078    }