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comparison org.eclipse.core.databinding/src/org/eclipse/core/internal/databinding/observable/StalenessObservableValue.d @ 78:0a55d2d5a946

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Added file for databinding
author Frank Benoit <benoit@tionex.de>
date Tue, 14 Apr 2009 11:35:29 +0200
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76:f05e6e8b2f2d 78:0a55d2d5a946
1 /*******************************************************************************
2 * Copyright (c) 2007, 2008 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * Boris Bokowski, IBM Corporation - initial API and implementation
10 * Matthew Hall - bug 212468
11 *******************************************************************************/
12 module org.eclipse.core.internal.databinding.observable.StalenessObservableValue;
13
14 import java.lang.all;
15
16 import org.eclipse.core.databinding.observable.ChangeEvent;
17 import org.eclipse.core.databinding.observable.Diffs;
18 import org.eclipse.core.databinding.observable.IChangeListener;
19 import org.eclipse.core.databinding.observable.IObservable;
20 import org.eclipse.core.databinding.observable.IStaleListener;
21 import org.eclipse.core.databinding.observable.StaleEvent;
22 import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
23
24 /**
25 * An observable value that tracks the staleness of an {@link IObservable}.
26 *
27 * @since 1.1
28 */
29 public class StalenessObservableValue : AbstractObservableValue {
30
31 private class MyListener : IChangeListener, IStaleListener {
32 public void handleChange(ChangeEvent event) {
33 if (stale && !event.getObservable().isStale()) {
34 stale = false;
35 fireValueChange(Diffs.createValueDiff(Boolean.TRUE,
36 Boolean.FALSE));
37 }
38 }
39
40 public void handleStale(StaleEvent staleEvent) {
41 if (!stale) {
42 stale = true;
43 fireValueChange(Diffs.createValueDiff(Boolean.FALSE,
44 Boolean.TRUE));
45 }
46 }
47 }
48
49 private IObservable tracked;
50 private bool stale;
51 private MyListener listener = new MyListener();
52
53 /**
54 * Constructs a StalenessObservableValue that tracks the staleness of the
55 * given {@link IObservable}.
56 *
57 * @param observable
58 * the observable to track
59 */
60 public this(IObservable observable) {
61 super(observable.getRealm());
62 this.tracked = observable;
63 this.stale = observable.isStale();
64 tracked.addChangeListener(listener);
65 tracked.addStaleListener(listener);
66 }
67
68 protected Object doGetValue() {
69 return tracked.isStale() ? Boolean.TRUE : Boolean.FALSE;
70 }
71
72 public Object getValueType() {
73 return Boolean.TYPE;
74 }
75
76 public synchronized void dispose() {
77 if (tracked !is null) {
78 tracked.removeChangeListener(listener);
79 tracked.removeStaleListener(listener);
80 tracked = null;
81 listener = null;
82 }
83 super.dispose();
84 }
85
86 }