1 /*
2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.nashorn.internal.runtime;
27
28 import java.util.Map;
29 import java.util.WeakHashMap;
30
31 /**
32 * Helper class to manage property listeners and notification.
33 */
34 public class PropertyListenerManager implements PropertyListener {
35 PropertyListenerManager() {}
36
37 /** property listeners for this object. */
38 private Map<PropertyListener,Boolean> listeners;
39
40 // These counters are updated in debug mode
41 private static int listenersAdded;
42 private static int listenersRemoved;
43
44 /**
45 * Return aggregate listeners added to all PropertyListenerManagers
46 * @return the listenersAdded
47 */
48 public static int getListenersAdded() {
49 return listenersAdded;
50 }
51
52 /**
53 * Return aggregate listeners removed from all PropertyListenerManagers
54 * @return the listenersRemoved
55 */
56 public static int getListenersRemoved() {
57 return listenersRemoved;
58 }
59
60 /**
61 * Return listeners added to this PropertyListenerManager.
62 * @return the listener count
63 */
64 public final int getListenerCount() {
65 return listeners != null? listeners.size() : 0;
66 }
67
68 // Property listener management methods
69
70 /**
71 * Add a property listener to this object.
72 *
73 * @param listener The property listener that is added.
74 */
75 public synchronized final void addPropertyListener(final PropertyListener listener) {
76 if (listeners == null) {
77 listeners = new WeakHashMap<>();
78 }
79
80 if (Context.DEBUG) {
81 listenersAdded++;
82 }
83 listeners.put(listener, Boolean.TRUE);
84 }
85
86 /**
87 * Remove a property listener from this object.
88 *
89 * @param listener The property listener that is removed.
90 */
91 public synchronized final void removePropertyListener(final PropertyListener listener) {
92 if (listeners != null) {
93 if (Context.DEBUG) {
94 listenersRemoved++;
95 }
96 listeners.remove(listener);
97 }
98 }
99
100 /**
101 * This method can be called to notify property addition to this object's listeners.
102 *
103 * @param object The ScriptObject to which property was added.
104 * @param prop The property being added.
105 */
106 protected synchronized final void notifyPropertyAdded(final ScriptObject object, final Property prop) {
107 if (listeners != null) {
108 for (PropertyListener listener : listeners.keySet()) {
109 listener.propertyAdded(object, prop);
110 }
111 }
112 }
113
114 /**
115 * This method can be called to notify property deletion to this object's listeners.
116 *
117 * @param object The ScriptObject from which property was deleted.
118 * @param prop The property being deleted.
119 */
120 protected synchronized final void notifyPropertyDeleted(final ScriptObject object, final Property prop) {
121 if (listeners != null) {
122 for (PropertyListener listener : listeners.keySet()) {
123 listener.propertyDeleted(object, prop);
124 }
125 }
126 }
127
128 /**
129 * This method can be called to notify property modification to this object's listeners.
130 *
131 * @param object The ScriptObject to which property was modified.
132 * @param oldProp The old property being replaced.
133 * @param newProp The new property that replaces the old property.
134 */
135 protected synchronized final void notifyPropertyModified(final ScriptObject object, final Property oldProp, final Property newProp) {
136 if (listeners != null) {
137 for (PropertyListener listener : listeners.keySet()) {
138 listener.propertyModified(object, oldProp, newProp);
139 }
140 }
141 }
142
143 /**
144 * This method can be called to notify __proto__ modification to this object's listeners.
145 *
146 * @param object The ScriptObject whose __proto__ was changed.
147 * @param oldProto old __proto__
148 * @param newProto new __proto__
149 */
150 protected synchronized final void notifyProtoChanged(final ScriptObject object, final ScriptObject oldProto, final ScriptObject newProto) {
151 if (listeners != null) {
152 for (PropertyListener listener : listeners.keySet()) {
153 listener.protoChanged(object, oldProto, newProto);
154 }
155 }
156 }
157
158 // PropertyListener methods
159
160 @Override
161 public final void propertyAdded(final ScriptObject object, final Property prop) {
162 notifyPropertyAdded(object, prop);
163 }
164
165 @Override
166 public final void propertyDeleted(final ScriptObject object, final Property prop) {
167 notifyPropertyDeleted(object, prop);
168 }
169
170 @Override
171 public final void propertyModified(final ScriptObject object, final Property oldProp, final Property newProp) {
172 notifyPropertyModified(object, oldProp, newProp);
173 }
174
175 @Override
176 public final void protoChanged(final ScriptObject object, final ScriptObject oldProto, final ScriptObject newProto) {
177 notifyProtoChanged(object, oldProto, newProto);
178 }
179 }