1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.jxpath;
18
19 import java.util.ArrayList;
20 import java.util.Collections;
21 import java.util.List;
22
23 /**
24 * A simple implementation of {@link NodeSet} that behaves as a collection
25 * of pointers.
26 *
27 * @author Dmitri Plotnikov
28 * @version $Revision: 652845 $ $Date: 2008-05-02 19:46:46 +0200 (Fr, 02 Mai 2008) $
29 */
30 public class BasicNodeSet implements NodeSet {
31 private List pointers = new ArrayList();
32 private List readOnlyPointers;
33 private List nodes;
34 private List values;
35
36 /**
37 * Add a pointer to this NodeSet.
38 * @param pointer to add
39 */
40 public void add(Pointer pointer) {
41 if (pointers.add(pointer)) {
42 clearCacheLists();
43 }
44 }
45
46 /**
47 * Add the specified NodeSet to this NodeSet.
48 * @param nodeSet to add
49 */
50 public void add(NodeSet nodeSet) {
51 if (pointers.addAll(nodeSet.getPointers())) {
52 clearCacheLists();
53 }
54 }
55
56 /**
57 * Remove a pointer from this NodeSet.
58 * @param pointer to remove
59 */
60 public void remove(Pointer pointer) {
61 if (pointers.remove(pointer)) {
62 clearCacheLists();
63 }
64 }
65
66 public synchronized List getPointers() {
67 if (readOnlyPointers == null) {
68 readOnlyPointers = Collections.unmodifiableList(pointers);
69 }
70 return readOnlyPointers;
71 }
72
73 public synchronized List getNodes() {
74 if (nodes == null) {
75 nodes = new ArrayList();
76 for (int i = 0; i < pointers.size(); i++) {
77 Pointer pointer = (Pointer) pointers.get(i);
78 nodes.add(pointer.getNode());
79 }
80 nodes = Collections.unmodifiableList(nodes);
81 }
82 return nodes;
83 }
84
85 public synchronized List getValues() {
86 if (values == null) {
87 values = new ArrayList();
88 for (int i = 0; i < pointers.size(); i++) {
89 Pointer pointer = (Pointer) pointers.get(i);
90 values.add(pointer.getValue());
91 }
92 values = Collections.unmodifiableList(values);
93 }
94 return values;
95 }
96
97 public String toString() {
98 return pointers.toString();
99 }
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 }