| /** |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.camel.processor.resequencer; |
| |
| import java.util.TreeSet; |
| |
| /** |
| * A sorted set of elements with additional methods for obtaining immediate |
| * successors and immediate predecessors of a given element in the sequence. |
| * Successors and predecessors are calculated by using a |
| * {@link SequenceElementComparator}. |
| * |
| * @version |
| */ |
| public class Sequence<E> extends TreeSet<E> { |
| |
| private static final long serialVersionUID = 5647393631147741711L; |
| |
| private SequenceElementComparator<E> comparator; |
| |
| /** |
| * Creates a new {@link Sequence} instance. |
| * |
| * @param comparator a strategy for comparing elements of this sequence. |
| */ |
| public Sequence(SequenceElementComparator<E> comparator) { |
| super(comparator); |
| this.comparator = comparator; |
| } |
| |
| /** |
| * Returns the immediate predecessor of the given element in this sequence |
| * or <code>null</code> if no predecessor exists. |
| * |
| * @param e an element which is compared to elements of this sequence. |
| * @return an element of this sequence or <code>null</code>. |
| */ |
| public E predecessor(E e) { |
| E elem = lower(e); |
| if (elem == null) { |
| return null; |
| } |
| if (comparator.predecessor(elem, e)) { |
| return elem; |
| } |
| return null; |
| } |
| |
| /** |
| * Returns the immediate successor of the given element in this sequence |
| * or <code>null</code> if no successor exists. |
| * |
| * @param e an element which is compared to elements of this sequence. |
| * @return an element of this sequence or <code>null</code>. |
| */ |
| public E successor(E e) { |
| E elem = higher(e); |
| if (elem == null) { |
| return null; |
| } |
| if (comparator.successor(elem, e)) { |
| return elem; |
| } |
| return null; |
| } |
| |
| /** |
| * Returns this sequence's comparator. |
| * |
| * @return this sequence's comparator. |
| */ |
| public SequenceElementComparator<E> comparator() { |
| return comparator; |
| } |
| |
| /** |
| * Returns the next higher element in the sequence to the given element. If |
| * the given element doesn't exist or if it is the last element in the |
| * sequence <code>null</code> is returned. <strong>Please note that this |
| * method is provided for compatibility with Java 5 SE. On a Java 6 SE |
| * platform the same method implemented by the {@link TreeSet} |
| * class should be used for better performance.</strong> |
| * |
| * @param e an element which is compared to elements of this sequence. |
| * @return an element of this sequence or <code>null</code>. |
| */ |
| public E higher(E e) { |
| boolean found = false; |
| for (E current : this) { |
| if (found) { |
| return current; |
| } |
| if (comparator.compare(e, current) == 0) { |
| found = true; |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Returns the next lower element in the sequence to the given element. If |
| * the given element doesn't exist or if it is the first element in the |
| * sequence <code>null</code> is returned. <strong>Please note that this |
| * method is provided for compatibility with Java 5 SE. On a Java 6 SE |
| * platform the same method implemented by the {@link TreeSet} |
| * class should be used for better performance.</strong> |
| * |
| * @param e an element which is compared to elements of this sequence. |
| * @return an element of this sequence or <code>null</code>. |
| */ |
| public E lower(E e) { |
| E last = null; |
| for (E current : this) { |
| if (comparator.compare(e, current) == 0) { |
| return last; |
| } |
| last = current; |
| } |
| return last; |
| } |
| |
| } |