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comparison org.eclipse.core.databinding.observable/src/org/eclipse/core/internal/databinding/observable/ValidatedObservableValue.d @ 95:6208d4f6a277

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Added trees for databinding.beans and observable
author Frank Benoit <benoit@tionex.de>
date Tue, 21 Apr 2009 10:55:51 +0200
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children b74ac5dfcc06
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94:1d37a7813832 95:6208d4f6a277
1 /*******************************************************************************
2 * Copyright (c) 2008 Matthew Hall 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 * Matthew Hall - initial API and implementation (bug 218269)
10 ******************************************************************************/
11
12 package org.eclipse.core.internal.databinding.observable;
13
14 import org.eclipse.core.databinding.observable.Diffs;
15 import org.eclipse.core.databinding.observable.IStaleListener;
16 import org.eclipse.core.databinding.observable.ObservableTracker;
17 import org.eclipse.core.databinding.observable.StaleEvent;
18 import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
19 import org.eclipse.core.databinding.observable.value.IObservableValue;
20 import org.eclipse.core.databinding.observable.value.IValueChangeListener;
21 import org.eclipse.core.databinding.observable.value.IVetoableValue;
22 import org.eclipse.core.databinding.observable.value.ValueChangeEvent;
23 import org.eclipse.core.databinding.observable.value.ValueChangingEvent;
24 import org.eclipse.core.internal.databinding.Util;
25 import org.eclipse.core.runtime.Assert;
26 import org.eclipse.core.runtime.IStatus;
27
28 /**
29 * An {@link IObservableValue} wrapper that stays in sync with the target
30 * observable as long as a given validation status is valid.
31 * <ul>
32 * <li>While status is valid, ValidatedObservableValue stays in sync with its
33 * target.
34 * <li>When status becomes invalid, ValidatedObservableValue will retain the
35 * last valid value of its target.
36 * <li>While status is invalid, changes in the target observable cause
37 * ValidatedObservableValue to fire a stale event, to indicate that changes are
38 * pending.
39 * <li>When status becomes valid, pending value changes are performed (if any)
40 * and synchronization resumes.
41 * </ul>
42 * <p>
43 * Note:
44 * <ul>
45 * <li>By default, a status is valid if its
46 * {@link IStatus#getSeverity() severity} is {@link IStatus#OK OK},
47 * {@link IStatus#INFO INFO}, or {@link IStatus#WARNING WARNING}
48 * <li>Calls to {@link #setValuecast(Object)} on the validated observable changes
49 * the value regardless of the validation status.
50 * <li>This class will not forward {@link ValueChangingEvent} events from a
51 * wrapped {@link IVetoableValue}.
52 * </ul>
53 *
54 * @since 1.2
55 */
56 public class ValidatedObservableValue : AbstractObservableValue {
57 private IObservableValue target;
58 private IObservableValue validationStatus;
59
60 private Object cachedValue;
61 private bool stale;
62 private bool updatingTarget = false;
63
64 private IValueChangeListener targetChangeListener = new class() IValueChangeListener {
65 public void handleValueChange(ValueChangeEvent event) {
66 if (updatingTarget)
67 return;
68 IStatus status = cast(IStatus) validationStatus.getValue();
69 if (isValid(status))
70 internalSetValue(event.diff.getNewValue(), false);
71 else
72 makeStale();
73 }
74 };
75
76 private static bool isValid(IStatus status) {
77 return status.isOK() || status.matches(IStatus.INFO | IStatus.WARNING);
78 }
79
80 private IStaleListener targetStaleListener = new class() IStaleListener {
81 public void handleStale(StaleEvent staleEvent) {
82 fireStale();
83 }
84 };
85
86 private IValueChangeListener validationStatusChangeListener = new class() IValueChangeListener {
87 public void handleValueChange(ValueChangeEvent event) {
88 IStatus oldStatus = cast(IStatus) event.diff.getOldValue();
89 IStatus newStatus = cast(IStatus) event.diff.getNewValue();
90 if (stale && !isValid(oldStatus) && isValid(newStatus)) {
91 internalSetValue(target.getValue(), false);
92 }
93 }
94 };
95
96 /**
97 * Constructs an observable value
98 *
99 * @param target
100 * the observable value to be wrapped
101 * @param validationStatus
102 * an observable value of type {@link IStatus}.class which
103 * contains the current validation status
104 */
105 public this(IObservableValue target,
106 IObservableValue validationStatus) {
107 super(target.getRealm());
108 Assert.isNotNull(validationStatus,
109 "Validation status observable cannot be null"); //$NON-NLS-1$
110 Assert
111 .isTrue(target.getRealm().equals(validationStatus.getRealm()),
112 "Target and validation status observables must be on the same realm"); //$NON-NLS-1$
113 this.target = target;
114 this.validationStatus = validationStatus;
115 this.cachedValue = target.getValue();
116
117 target.addValueChangeListener(targetChangeListener);
118 target.addStaleListener(targetStaleListener);
119 validationStatus.addValueChangeListener(validationStatusChangeListener);
120 }
121
122 private void makeStale() {
123 if (!stale) {
124 stale = true;
125 fireStale();
126 }
127 }
128
129 public bool isStale() {
130 ObservableTracker.getterCalled(this);
131 return stale || target.isStale();
132 }
133
134 protected Object doGetValue() {
135 return cachedValue;
136 }
137
138 private void internalSetValue(Object value, bool updateTarget) {
139 Object oldValue = cachedValue;
140 cachedValue = value;
141 if (updateTarget) {
142 updatingTarget = true;
143 try {
144 target.setValue(value);
145 cachedValue = target.getValue();
146 } finally {
147 updatingTarget = false;
148 }
149 }
150 stale = false;
151 if (!Util.equals(oldValue, cachedValue))
152 fireValueChange(Diffs.createValueDiff(oldValue, cachedValue));
153 }
154
155 protected void doSetValue(Object value) {
156 internalSetValue(value, true);
157 }
158
159 public Object getValueType() {
160 return target.getValueType();
161 }
162
163 public synchronized void dispose() {
164 target.removeValueChangeListener(targetChangeListener);
165 target.removeStaleListener(targetStaleListener);
166 validationStatus
167 .removeValueChangeListener(validationStatusChangeListener);
168 super.dispose();
169 }
170 }