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Java > Open Source Codes > org > eclipse > jface > internal > databinding > internal > observable > NestedObservableValue


1 /*******************************************************************************
2  * Copyright (c) 2005, 2006 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  * IBM Corporation - initial API and implementation
10  *******************************************************************************/
11 package org.eclipse.jface.internal.databinding.internal.observable;
12
13 import org.eclipse.jface.internal.databinding.provisional.DataBindingContext;
14 import org.eclipse.jface.internal.databinding.provisional.description.Property;
15 import org.eclipse.jface.internal.databinding.provisional.observable.Diffs;
16 import org.eclipse.jface.internal.databinding.provisional.observable.value.AbstractObservableValue;
17 import org.eclipse.jface.internal.databinding.provisional.observable.value.IObservableValue;
18 import org.eclipse.jface.internal.databinding.provisional.observable.value.IValueChangeListener;
19 import org.eclipse.jface.internal.databinding.provisional.observable.value.ValueDiff;
20 import org.eclipse.jface.util.Assert;
21
22 /**
23  * @since 1.0
24  *
25  */
26 public class NestedObservableValue extends AbstractObservableValue {
27
28     private boolean updating = false;
29
30     private IValueChangeListener innerChangeListener = new IValueChangeListener() {
31         public void handleValueChange(IObservableValue source, ValueDiff diff) {
32             if (!updating) {
33                 fireValueChange(diff);
34             }
35         }
36     };
37
38     private Object JavaDoc currentOuterValue;
39
40     private Object JavaDoc feature;
41
42     private IObservableValue innerObservableValue;
43
44     private DataBindingContext databindingContext;
45
46     private Object JavaDoc featureType;
47
48     private IObservableValue outerObservableValue;
49
50     /**
51      * @param databindingContext
52      * @param outerObservableValue
53      * @param feature
54      * @param featureType
55      */
56     public NestedObservableValue(DataBindingContext databindingContext,
57             IObservableValue outerObservableValue, Object JavaDoc feature,
58             Class JavaDoc featureType) {
59         this.databindingContext = databindingContext;
60         this.feature = feature;
61         this.featureType = featureType;
62         this.outerObservableValue = outerObservableValue;
63         updateInnerObservableValue(outerObservableValue);
64
65         outerObservableValue.addValueChangeListener(outerChangeListener);
66     }
67
68     IValueChangeListener outerChangeListener = new IValueChangeListener() {
69         public void handleValueChange(IObservableValue source, ValueDiff diff) {
70             Object JavaDoc oldValue = doGetValue();
71             updateInnerObservableValue(outerObservableValue);
72             fireValueChange(Diffs.createValueDiff(oldValue, doGetValue()));
73         }
74     };
75
76     private void updateInnerObservableValue(
77             IObservableValue outerObservableValue) {
78         currentOuterValue = outerObservableValue.getValue();
79         if (innerObservableValue != null) {
80             innerObservableValue.removeValueChangeListener(innerChangeListener);
81             innerObservableValue.dispose();
82         }
83         if (currentOuterValue == null) {
84             innerObservableValue = null;
85         } else {
86             this.innerObservableValue = (IObservableValue) databindingContext
87                     .createObservable(new Property(currentOuterValue, feature));
88             Object JavaDoc innerValueType = innerObservableValue.getValueType();
89             if (featureType == null) {
90                 featureType = innerValueType;
91             } else {
92                 Assert
93                         .isTrue(featureType.equals(innerValueType),
94                                 "Cannot change value type in a nested observable value"); //$NON-NLS-1$
95 }
96             innerObservableValue.addValueChangeListener(innerChangeListener);
97         }
98     }
99
100     public void setValue(Object JavaDoc value) {
101         if (innerObservableValue != null)
102             innerObservableValue.setValue(value);
103     }
104
105     public Object JavaDoc doGetValue() {
106         return innerObservableValue == null ? null : innerObservableValue
107                 .getValue();
108     }
109
110     public Object JavaDoc getValueType() {
111         return featureType;
112     }
113
114     public void dispose() {
115         super.dispose();
116
117         if (outerObservableValue != null) {
118             outerObservableValue.removeValueChangeListener(outerChangeListener);
119             outerObservableValue.dispose();
120         }
121         if (innerObservableValue != null) {
122             innerObservableValue.removeValueChangeListener(innerChangeListener);
123             innerObservableValue.dispose();
124         }
125         currentOuterValue = null;
126         databindingContext = null;
127         feature = null;
128         innerObservableValue = null;
129         innerChangeListener = null;
130     }
131
132 }
133
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