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 java.util.Comparator;
020    
021    /**
022     * A strategy for comparing elements of a sequence.
023     * 
024     * @version 
025     */
026    public interface SequenceElementComparator<E> extends Comparator<E> {
027    
028        /**
029         * Returns <code>true</code> if <code>o1</code> is an immediate predecessor
030         * of <code>o2</code>.
031         * 
032         * @param o1 a sequence element.
033         * @param o2 a sequence element.
034         * @return true if its an immediate predecessor
035         */
036        boolean predecessor(E o1, E o2);
037        
038        /**
039         * Returns <code>true</code> if <code>o1</code> is an immediate successor
040         * of <code>o2</code>.
041         * 
042         * @param o1 a sequence element.
043         * @param o2 a sequence element.
044         * @return true if its an immediate successor
045         */
046        boolean successor(E o1, E o2);
047    
048        /**
049         * Returns <tt>true</tt> if the <code>o1</code> can be used in this comparator.
050         *
051         * @param o1 a sequence element
052         * @return true if its usable for this comparator
053         */
054        boolean isValid(E o1);
055        
056    }