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 */
017package org.apache.camel.processor.resequencer;
018
019import org.apache.camel.Exchange;
020import 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 */
029public 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}