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;
018    
019    import java.util.Comparator;
020    import java.util.List;
021    import java.util.Set;
022    import java.util.TreeSet;
023    
024    import org.apache.camel.Exchange;
025    import org.apache.camel.Expression;
026    import org.apache.camel.Processor;
027    import org.apache.camel.util.ExpressionComparator;
028    import org.apache.camel.util.ExpressionListComparator;
029    
030    /**
031     * An implementation of the <a href="http://activemq.apache.org/camel/resequencer.html">Resequencer</a>
032     * which can reorder messages within a batch.
033     *
034     * @version $Revision: 64127 $
035     */
036    public class Resequencer extends BatchProcessor {
037        public Resequencer(Processor processor, Expression expression) {
038            this(processor, createSet(expression));
039        }
040    
041        public Resequencer(Processor processor, List<Expression> expressions) {
042            this(processor, createSet(expressions));
043        }
044    
045        public Resequencer(Processor processor, Set<Exchange> collection) {
046            super(processor, collection);
047        }
048    
049        @Override
050        public String toString() {
051            return "Resequencer[to: " + getProcessor() + "]";
052        }
053    
054        // Implementation methods
055        //-------------------------------------------------------------------------
056    
057        protected static Set<Exchange> createSet(Expression<Exchange> expression) {
058            return createSet(new ExpressionComparator<Exchange>(expression));
059        }
060    
061        protected static Set<Exchange> createSet(List<Expression> expressions) {
062            if (expressions.size() == 1) {
063                return createSet(expressions.get(0));
064            }
065            return createSet(new ExpressionListComparator(expressions));
066        }
067    
068        protected static Set<Exchange> createSet(Comparator<? super Exchange> comparator) {
069            return new TreeSet<Exchange>(comparator);
070        }
071    }