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.commons.jxpath;
018
019 import java.util.ArrayList;
020 import java.util.Collections;
021 import java.util.List;
022
023 /**
024 * A simple implementation of {@link NodeSet} that behaves as a collection
025 * of pointers.
026 *
027 * @author Dmitri Plotnikov
028 * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
029 */
030 public class BasicNodeSet implements NodeSet {
031 private List pointers = new ArrayList();
032 private List readOnlyPointers;
033 private List nodes;
034 private List values;
035
036 /**
037 * Add a pointer to this NodeSet.
038 * @param pointer to add
039 */
040 public void add(Pointer pointer) {
041 if (pointers.add(pointer)) {
042 clearCacheLists();
043 }
044 }
045
046 /**
047 * Add the specified NodeSet to this NodeSet.
048 * @param nodeSet to add
049 */
050 public void add(NodeSet nodeSet) {
051 if (pointers.addAll(nodeSet.getPointers())) {
052 clearCacheLists();
053 }
054 }
055
056 /**
057 * Remove a pointer from this NodeSet.
058 * @param pointer to remove
059 */
060 public void remove(Pointer pointer) {
061 if (pointers.remove(pointer)) {
062 clearCacheLists();
063 }
064 }
065
066 public synchronized List getPointers() {
067 if (readOnlyPointers == null) {
068 readOnlyPointers = Collections.unmodifiableList(pointers);
069 }
070 return readOnlyPointers;
071 }
072
073 public synchronized List getNodes() {
074 if (nodes == null) {
075 nodes = new ArrayList();
076 for (int i = 0; i < pointers.size(); i++) {
077 Pointer pointer = (Pointer) pointers.get(i);
078 nodes.add(pointer.getNode());
079 }
080 nodes = Collections.unmodifiableList(nodes);
081 }
082 return nodes;
083 }
084
085 public synchronized List getValues() {
086 if (values == null) {
087 values = new ArrayList();
088 for (int i = 0; i < pointers.size(); i++) {
089 Pointer pointer = (Pointer) pointers.get(i);
090 values.add(pointer.getValue());
091 }
092 values = Collections.unmodifiableList(values);
093 }
094 return values;
095 }
096
097 public String toString() {
098 return pointers.toString();
099 }
100
101 /**
102 * Clear cache list members.
103 */
104 private synchronized void clearCacheLists() {
105 readOnlyPointers = null;
106 nodes = null;
107 values = null;
108 }
109
110 }