1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
/*******************************************************************************
* Copyright (c) 2008 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0, which accompanies this distribution
* and is available at http://www.eclipse.org/legal/epl-v10.html.
*
* Contributors:
* Oracle - initial API and implementation
******************************************************************************/
package org.eclipse.jpt.utility.internal.model.value;
import java.util.Iterator;
import java.util.ListIterator;
import org.eclipse.jpt.utility.internal.iterators.EmptyListIterator;
import org.eclipse.jpt.utility.internal.iterators.SingleElementListIterator;
import org.eclipse.jpt.utility.internal.model.AbstractModel;
import org.eclipse.jpt.utility.internal.model.ChangeSupport;
import org.eclipse.jpt.utility.internal.model.SingleAspectChangeSupport;
import org.eclipse.jpt.utility.model.event.PropertyChangeEvent;
import org.eclipse.jpt.utility.model.listener.ListChangeListener;
import org.eclipse.jpt.utility.model.listener.PropertyChangeListener;
import org.eclipse.jpt.utility.model.value.ListValueModel;
import org.eclipse.jpt.utility.model.value.PropertyValueModel;
/**
* An adapter that allows us to make a PropertyValueModel behave like
* a read-only, single-element ListValueModel, sorta.
*
* If the property's value is null, an empty iterator is returned
* (i.e. you can't have a list with a null element).
*/
public class PropertyListValueModelAdapter<E>
extends AbstractModel
implements ListValueModel<E>
{
/** The wrapped property value model. */
protected final PropertyValueModel<? extends E> valueHolder;
/** A listener that forwards any events fired by the value holder. */
protected final PropertyChangeListener propertyChangeListener;
/** Cache the value. */
protected E value;
// ********** constructors/initialization **********
/**
* Wrap the specified property value model.
*/
public PropertyListValueModelAdapter(PropertyValueModel<? extends E> valueHolder) {
super();
if (valueHolder == null) {
throw new NullPointerException();
}
this.valueHolder = valueHolder;
this.propertyChangeListener = this.buildPropertyChangeListener();
// postpone building the value and listening to the underlying value
// until we have listeners ourselves...
}
@Override
protected ChangeSupport buildChangeSupport() {
return new SingleAspectChangeSupport(this, ListChangeListener.class, LIST_VALUES);
}
/**
* The wrapped value has changed, forward an equivalent
* list change event to our listeners.
*/
protected PropertyChangeListener buildPropertyChangeListener() {
return new PropertyChangeListener() {
@SuppressWarnings("unchecked")
public void propertyChanged(PropertyChangeEvent event) {
PropertyListValueModelAdapter.this.valueChanged((E) event.getNewValue());
}
@Override
public String toString() {
return "property change listener";
}
};
}
// ********** ListValueModel implementation **********
public Iterator<E> iterator() {
return this.listIterator();
}
public ListIterator<E> listIterator() {
return (this.value == null) ?
EmptyListIterator.<E>instance()
:
new SingleElementListIterator<E>(this.value);
}
public int size() {
return (this.value == null) ? 0 : 1;
}
public E get(int index) {
if (this.value == null) {
throw this.ioobe(index, 0);
}
if (index > 0) {
throw this.ioobe(index, 1);
}
return this.value;
}
protected static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
public Object[] toArray() {
return (this.value == null) ? EMPTY_OBJECT_ARRAY : new Object[] {this.value};
}
// ********** extend change support **********
/**
* Override to start listening to the value holder if necessary.
*/
@Override
public void addListChangeListener(ListChangeListener listener) {
if (this.hasNoListeners()) {
this.engageModel();
}
super.addListChangeListener(listener);
}
/**
* Override to start listening to the value holder if necessary.
*/
@Override
public void addListChangeListener(String listName, ListChangeListener listener) {
if (listName == LIST_VALUES && this.hasNoListeners()) {
this.engageModel();
}
super.addListChangeListener(listName, listener);
}
/**
* Override to stop listening to the value holder if appropriate.
*/
@Override
public void removeListChangeListener(ListChangeListener listener) {
super.removeListChangeListener(listener);
if (this.hasNoListeners()) {
this.disengageModel();
}
}
/**
* Override to stop listening to the value holder if appropriate.
*/
@Override
public void removeListChangeListener(String listName, ListChangeListener listener) {
super.removeListChangeListener(listName, listener);
if (listName == LIST_VALUES && this.hasNoListeners()) {
this.disengageModel();
}
}
// ********** queries **********
protected boolean hasListeners() {
return this.hasAnyListChangeListeners(LIST_VALUES);
}
protected boolean hasNoListeners() {
return ! this.hasListeners();
}
// ********** behavior **********
protected IndexOutOfBoundsException ioobe(int index, int size) {
return new IndexOutOfBoundsException("Index: " + index + ", Size: " + size);
}
protected void engageModel() {
this.valueHolder.addPropertyChangeListener(PropertyValueModel.VALUE, this.propertyChangeListener);
// synch our value *after* we start listening to the value holder,
// since its value might change when a listener is added
this.value = this.valueHolder.getValue();
}
protected void disengageModel() {
this.valueHolder.removePropertyChangeListener(PropertyValueModel.VALUE, this.propertyChangeListener);
// clear out the value when we are not listening to the value holder
this.value = null;
}
/**
* synchronize our internal value with the wrapped value
* and fire the appropriate events
*/
protected void valueChanged(E newValue) {
E oldValue = this.value;
this.value = newValue;
if (oldValue == null) {
this.fireItemAdded(LIST_VALUES, 0, newValue);
} else {
if (newValue == null) {
this.fireItemRemoved(LIST_VALUES, 0, oldValue);
} else {
this.fireItemReplaced(LIST_VALUES, 0, newValue, oldValue);
}
}
}
@Override
public void toString(StringBuilder sb) {
sb.append(this.valueHolder);
}
}
|
