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comparison org.eclipse.core.databinding/src/org/eclipse/core/internal/databinding/observable/ValidatedObservableValue.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) 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 module org.eclipse.core.internal.databinding.observable.ValidatedObservableValue;
13
14 import java.lang.all;
15
16 import org.eclipse.core.databinding.observable.Diffs;
17 import org.eclipse.core.databinding.observable.IStaleListener;
18 import org.eclipse.core.databinding.observable.ObservableTracker;
19 import org.eclipse.core.databinding.observable.StaleEvent;
20 import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
21 import org.eclipse.core.databinding.observable.value.IObservableValue;
22 import org.eclipse.core.databinding.observable.value.IValueChangeListener;
23 import org.eclipse.core.databinding.observable.value.IVetoableValue;
24 import org.eclipse.core.databinding.observable.value.ValueChangeEvent;
25 import org.eclipse.core.databinding.observable.value.ValueChangingEvent;
26 import org.eclipse.core.internal.databinding.Util;
27 import org.eclipse.core.runtime.Assert;
28 import org.eclipse.core.runtime.IStatus;
29
30 /**
31 * An {@link IObservableValue} wrapper that stays in sync with the target
32 * observable as long as a given validation status is valid.
33 * <ul>
34 * <li>While status is valid, ValidatedObservableValue stays in sync with its
35 * target.
36 * <li>When status becomes invalid, ValidatedObservableValue will retain the
37 * last valid value of its target.
38 * <li>While status is invalid, changes in the target observable cause
39 * ValidatedObservableValue to fire a stale event, to indicate that changes are
40 * pending.
41 * <li>When status becomes valid, pending value changes are performed (if any)
42 * and synchronization resumes.
43 * </ul>
44 * <p>
45 * Note:
46 * <ul>
47 * <li>By default, a status is valid if its
48 * {@link IStatus#getSeverity() severity} is {@link IStatus#OK OK},
49 * {@link IStatus#INFO INFO}, or {@link IStatus#WARNING WARNING}
50 * <li>Calls to {@link #setValuecast(Object)} on the validated observable changes
51 * the value regardless of the validation status.
52 * <li>This class will not forward {@link ValueChangingEvent} events from a
53 * wrapped {@link IVetoableValue}.
54 * </ul>
55 *
56 * @since 1.2
57 */
58 public class ValidatedObservableValue : AbstractObservableValue {
59 private IObservableValue target;
60 private IObservableValue validationStatus;
61
62 private Object cachedValue;
63 private bool stale;
64 private bool updatingTarget = false;
65
66 private IValueChangeListener targetChangeListener = new class() IValueChangeListener {
67 public void handleValueChange(ValueChangeEvent event) {
68 if (updatingTarget)
69 return;
70 IStatus status = cast(IStatus) validationStatus.getValue();
71 if (isValid(status))
72 internalSetValue(event.diff.getNewValue(), false);
73 else
74 makeStale();
75 }
76 };
77
78 private static bool isValid(IStatus status) {
79 return status.isOK() || status.matches(IStatus.INFO | IStatus.WARNING);
80 }
81
82 private IStaleListener targetStaleListener = new class() IStaleListener {
83 public void handleStale(StaleEvent staleEvent) {
84 fireStale();
85 }
86 };
87
88 private IValueChangeListener validationStatusChangeListener = new class() IValueChangeListener {
89 public void handleValueChange(ValueChangeEvent event) {
90 IStatus oldStatus = cast(IStatus) event.diff.getOldValue();
91 IStatus newStatus = cast(IStatus) event.diff.getNewValue();
92 if (stale && !isValid(oldStatus) && isValid(newStatus)) {
93 internalSetValue(target.getValue(), false);
94 }
95 }
96 };
97
98 /**
99 * Constructs an observable value
100 *
101 * @param target
102 * the observable value to be wrapped
103 * @param validationStatus
104 * an observable value of type {@link IStatus}.classinfo which
105 * contains the current validation status
106 */
107 public this(IObservableValue target,
108 IObservableValue validationStatus) {
109 super(target.getRealm());
110 Assert.isNotNull(validationStatus,
111 "Validation status observable cannot be null"); //$NON-NLS-1$
112 Assert
113 .isTrue(target.getRealm().equals(validationStatus.getRealm()),
114 "Target and validation status observables must be on the same realm"); //$NON-NLS-1$
115 this.target = target;
116 this.validationStatus = validationStatus;
117 this.cachedValue = target.getValue();
118
119 target.addValueChangeListener(targetChangeListener);
120 target.addStaleListener(targetStaleListener);
121 validationStatus.addValueChangeListener(validationStatusChangeListener);
122 }
123
124 private void makeStale() {
125 if (!stale) {
126 stale = true;
127 fireStale();
128 }
129 }
130
131 public bool isStale() {
132 ObservableTracker.getterCalled(this);
133 return stale || target.isStale();
134 }
135
136 protected Object doGetValue() {
137 return cachedValue;
138 }
139
140 private void internalSetValue(Object value, bool updateTarget) {
141 Object oldValue = cachedValue;
142 cachedValue = value;
143 if (updateTarget) {
144 updatingTarget = true;
145 try {
146 target.setValue(value);
147 cachedValue = target.getValue();
148 } finally {
149 updatingTarget = false;
150 }
151 }
152 stale = false;
153 if (!Util.equals(oldValue, cachedValue))
154 fireValueChange(Diffs.createValueDiff(oldValue, cachedValue));
155 }
156
157 protected void doSetValue(Object value) {
158 internalSetValue(value, true);
159 }
160
161 public Object getValueType() {
162 return target.getValueType();
163 }
164
165 public synchronized void dispose() {
166 target.removeValueChangeListener(targetChangeListener);
167 target.removeStaleListener(targetStaleListener);
168 validationStatus
169 .removeValueChangeListener(validationStatusChangeListener);
170 super.dispose();
171 }
172 }