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comparison org.eclipse.equinox.common/src/org/eclipse/core/runtime/ListenerList.d @ 105:bbe49769ec18

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author Frank Benoit <benoit@tionex.de>
date Sun, 08 Nov 2009 12:42:30 +0100
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104:88652073d1c2 105:bbe49769ec18
2 * Copyright (c) 2004, 2006 IBM Corporation and others. 2 * Copyright (c) 2004, 2006 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials 3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0 4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at 5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html 6 * http://www.eclipse.org/legal/epl-v10.html
7 * 7 *
8 * Contributors: 8 * Contributors:
9 * IBM Corporation - initial API and implementation 9 * IBM Corporation - initial API and implementation
10 * Port to the D programming language:
11 * Frank Benoit <benoit@tionex.de>
12 *******************************************************************************/ 10 *******************************************************************************/
13 module org.eclipse.core.runtime.ListenerList; 11 // Port to the D programming language:
12 // Frank Benoit <benoit@tionex.de>
13 module org.eclipse.core.runtimeListenerList;
14 14
15 import java.lang.all; 15 import java.lang.all;
16 16
17
17 /** 18 /**
18 * This class is a thread safe list that is designed for storing lists of listeners. 19 * This class is a thread safe list that is designed for storing lists of listeners.
19 * The implementation is optimized for minimal memory footprint, frequent reads 20 * The implementation is optimized for minimal memory footprint, frequent reads
20 * and infrequent writes. Modification of the list is synchronized and relatively 21 * and infrequent writes. Modification of the list is synchronized and relatively
21 * expensive, while accessing the listeners is very fast. Readers are given access 22 * expensive, while accessing the listeners is very fast. Readers are given access
22 * to the underlying array data structure for reading, with the trust that they will 23 * to the underlying array data structure for reading, with the trust that they will
23 * not modify the underlying array. 24 * not modify the underlying array.
24 * <p> 25 * <p>
25 * <a name="same">A listener list handles the <i>same</i> listener being added 26 * <a name="same">A listener list handles the <i>same</i> listener being added
26 * multiple times, and tolerates removal of listeners that are the same as other 27 * multiple times, and tolerates removal of listeners that are the same as other
27 * listeners in the list. For this purpose, listeners can be compared with each other 28 * listeners in the list. For this purpose, listeners can be compared with each other
28 * using either equality or identity, as specified in the list constructor. 29 * using either equality or identity, as specified in the list constructor.
29 * </p> 30 * </p>
30 * <p> 31 * <p>
31 * Use the <code>getListeners</code> method when notifying listeners. The recommended 32 * Use the <code>getListeners</code> method when notifying listeners. The recommended
32 * code sequence for notifying all registered listeners of say, 33 * code sequence for notifying all registered listeners of say,
33 * <code>FooListener.eventHappened</code>, is: 34 * <code>FooListener.eventHappened</code>, is:
34 * 35 *
35 * <pre> 36 * <pre>
36 * Object[] listeners = myListenerList.getListeners(); 37 * Object[] listeners = myListenerList.getListeners();
37 * for (int i = 0; i &lt; listeners.length; ++i) { 38 * for (int i = 0; i &lt; listeners.length; ++i) {
38 * ((FooListener) listeners[i]).eventHappened(event); 39 * ((FooListener) listeners[i]).eventHappened(event);
39 * } 40 * }
40 * </pre> 41 * </pre>
41 * 42 *
42 * </p><p> 43 * </p><p>
43 * This class can be used without OSGi running. 44 * This class can be used without OSGi running.
44 * </p> 45 * </p>
45 * @since org.eclipse.equinox.common 3.2 46 * @since org.eclipse.equinox.common 3.2
46 */ 47 */
47 public class ListenerList { 48 public class ListenerList {
48 49
49 /** 50 /**
50 * The empty array singleton instance. 51 * The empty array singleton instance.
51 */ 52 */
52 private static const Object[] EmptyArray; 53 private static final Object[] EmptyArray = new Object[0];
53 54
54 /** 55 /**
55 * Mode constant (value 0) indicating that listeners should be considered 56 * Mode constant (value 0) indicating that listeners should be considered
56 * the <a href="#same">same</a> if they are equal. 57 * the <a href="#same">same</a> if they are equal.
57 */ 58 */
58 public static const int EQUALITY = 0; 59 public static final int EQUALITY = 0;
59 60
60 /** 61 /**
61 * Mode constant (value 1) indicating that listeners should be considered 62 * Mode constant (value 1) indicating that listeners should be considered
62 * the <a href="#same">same</a> if they are identical. 63 * the <a href="#same">same</a> if they are identical.
63 */ 64 */
64 public static const int IDENTITY = 1; 65 public static final int IDENTITY = 1;
65 66
66 /** 67 /**
67 * Indicates the comparison mode used to determine if two 68 * Indicates the comparison mode used to determine if two
68 * listeners are equivalent 69 * listeners are equivalent
69 */ 70 */
70 private final bool identity; 71 private final bool identity;
71 72
72 /** 73 /**
73 * The list of listeners. Initially empty but initialized 74 * The list of listeners. Initially empty but initialized
74 * to an array of size capacity the first time a listener is added. 75 * to an array of size capacity the first time a listener is added.
75 * Maintains invariant: listeners !is null 76 * Maintains invariant: listeners != null
76 */ 77 */
77 private Object[] listeners; 78 private /+volatile+/ Object[] listeners = EmptyArray;
78 79
79 /** 80 /**
80 * Creates a listener list in which listeners are compared using equality. 81 * Creates a listener list in which listeners are compared using equality.
81 */ 82 */
82 public this() { 83 public this() {
83 this(EQUALITY); 84 thiscast(EQUALITY);
84 } 85 }
85 86
86 /** 87 /**
87 * Creates a listener list using the provided comparison mode. 88 * Creates a listener list using the provided comparison mode.
88 * 89 *
89 * @param mode The mode used to determine if listeners are the <a href="#same">same</a>. 90 * @param mode The mode used to determine if listeners are the <a href="#same">same</a>.
90 */ 91 */
91 public this(int mode) { 92 public this(int mode) {
92 if (mode !is EQUALITY && mode !is IDENTITY) 93 if (mode !is EQUALITY && mode !is IDENTITY)
93 throw new IllegalArgumentException( null ); 94 throw new IllegalArgumentException();
94 this.identity = mode is IDENTITY; 95 this.identity = mode is IDENTITY;
95 } 96 }
96 97
97 /** 98 /**
98 * Adds a listener to this list. This method has no effect if the <a href="#same">same</a> 99 * Adds a listener to this list. This method has no effect if the <a href="#same">same</a>
99 * listener is already registered. 100 * listener is already registered.
100 * 101 *
101 * @param listener the non-<code>null</code> listener to add 102 * @param listener the non-<code>null</code> listener to add
102 */ 103 */
103 public synchronized void add(Object listener) { 104 public synchronized void add(Object listener) {
104 // This method is synchronized to protect against multiple threads adding 105 // This method is synchronized to protect against multiple threads adding
105 // or removing listeners concurrently. This does not block concurrent readers. 106 // or removing listeners concurrently. This does not block concurrent readers.
106 if (listener is null) 107 if (listener is null)
107 throw new IllegalArgumentException( null ); 108 throw new IllegalArgumentException();
108 // check for duplicates 109 // check for duplicates
109 final int oldSize = listeners.length; 110 final int oldSize = listeners.length;
110 for (int i = 0; i < oldSize; ++i) { 111 for (int i = 0; i < oldSize; ++i) {
111 Object listener2 = listeners[i]; 112 Object listener2 = listeners[i];
112 if (identity ? listener is listener2 : listener.opEquals(listener2)) 113 if (identity ? listener is listener2 : listener.opEquals(listener2))
113 return; 114 return;
123 /** 124 /**
124 * Returns an array containing all the registered listeners. 125 * Returns an array containing all the registered listeners.
125 * The resulting array is unaffected by subsequent adds or removes. 126 * The resulting array is unaffected by subsequent adds or removes.
126 * If there are no listeners registered, the result is an empty array. 127 * If there are no listeners registered, the result is an empty array.
127 * Use this method when notifying listeners, so that any modifications 128 * Use this method when notifying listeners, so that any modifications
128 * to the listener list during the notification will have no effect on 129 * to the listener list during the notification will have no effect on
129 * the notification itself. 130 * the notification itself.
130 * <p> 131 * <p>
131 * Note: Callers of this method <b>must not</b> modify the returned array. 132 * Note: Callers of this method <b>must not</b> modify the returned array.
132 * 133 *
133 * @return the list of registered listeners 134 * @return the list of registered listeners
134 */ 135 */
135 public Object[] getListeners() { 136 public Object[] getListeners() {
136 return listeners; 137 return listeners;
145 public bool isEmpty() { 146 public bool isEmpty() {
146 return listeners.length is 0; 147 return listeners.length is 0;
147 } 148 }
148 149
149 /** 150 /**
150 * Removes a listener from this list. Has no effect if the <a href="#same">same</a> 151 * Removes a listener from this list. Has no effect if the <a href="#same">same</a>
151 * listener was not already registered. 152 * listener was not already registered.
152 * 153 *
153 * @param listener the non-<code>null</code> listener to remove 154 * @param listener the non-<code>null</code> listener to remove
154 */ 155 */
155 public synchronized void remove(Object listener) { 156 public synchronized void remove(Object listener) {
156 // This method is synchronized to protect against multiple threads adding 157 // This method is synchronized to protect against multiple threads adding
157 // or removing listeners concurrently. This does not block concurrent readers. 158 // or removing listeners concurrently. This does not block concurrent readers.
158 if (listener is null) 159 if (listener is null)
159 throw new IllegalArgumentException( null ); 160 throw new IllegalArgumentException();
160 int oldSize = listeners.length; 161 int oldSize = listeners.length;
161 for (int i = 0; i < oldSize; ++i) { 162 for (int i = 0; i < oldSize; ++i) {
162 Object listener2 = listeners[i]; 163 Object listener2 = listeners[i];
163 if (identity ? listener is listener2 : listener.opEquals(listener2)) { 164 if (identity ? listener is listener2 : listener.opEquals(listener2)) {
164 if (oldSize is 1) { 165 if (oldSize is 1) {
182 * @return the number of registered listeners 183 * @return the number of registered listeners
183 */ 184 */
184 public int size() { 185 public int size() {
185 return listeners.length; 186 return listeners.length;
186 } 187 }
187 188
188 /** 189 /**
189 * Removes all listeners from this list. 190 * Removes all listeners from this list.
190 */ 191 */
191 public synchronized void clear() { 192 public synchronized void clear() {
192 listeners = EmptyArray; 193 listeners = EmptyArray;