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comparison org.eclipse.core.databinding.observable/src/org/eclipse/core/databinding/observable/value/WritableValue.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) 2006, 2007 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 * Brad Reynolds - bug 158687
11 * Brad Reynolds - bug 164653, 147515
12 *******************************************************************************/
13
14 package org.eclipse.core.databinding.observable.value;
15
16 import org.eclipse.core.databinding.observable.Diffs;
17 import org.eclipse.core.databinding.observable.Realm;
18
19 /**
20 * Mutable (writable) implementation of {@link IObservableValue} that will maintain a value and fire
21 * change events when the value changes.
22 * <p>
23 * This class is thread safe. All state accessing methods must be invoked from
24 * the {@link Realm#isCurrent() current realm}. Methods for adding and removing
25 * listeners may be invoked from any thread.
26 * </p>
27 * @since 1.0
28 */
29 public class WritableValue : AbstractObservableValue {
30
31 private final Object valueType;
32
33 /**
34 * Constructs a new instance with the default realm, a <code>null</code>
35 * value type, and a <code>null</code> value.
36 */
37 public this() {
38 this(null, null);
39 }
40
41 /**
42 * Constructs a new instance with the default realm.
43 *
44 * @param initialValue
45 * can be <code>null</code>
46 * @param valueType
47 * can be <code>null</code>
48 */
49 public this(Object initialValue, Object valueType) {
50 this(Realm.getDefault(), initialValue, valueType);
51 }
52
53 /**
54 * Constructs a new instance with the provided <code>realm</code>, a
55 * <code>null</code> value type, and a <code>null</code> initial value.
56 *
57 * @param realm
58 */
59 public this(Realm realm) {
60 this(realm, null, null);
61 }
62
63 /**
64 * Constructs a new instance.
65 *
66 * @param realm
67 * @param initialValue
68 * can be <code>null</code>
69 * @param valueType
70 * can be <code>null</code>
71 */
72 public this(Realm realm, Object initialValue, Object valueType) {
73 super(realm);
74 this.valueType = valueType;
75 this.value = initialValue;
76 }
77
78 private Object value = null;
79
80 public Object doGetValue() {
81 return value;
82 }
83
84 /**
85 * @param value
86 * The value to set.
87 */
88 public void doSetValue(Object value) {
89 bool changed = false;
90
91 if (this.value is null && value !is null) {
92 changed = true;
93 } else if (this.value !is null && !this.value.equals(value)) {
94 changed = true;
95 }
96
97 if (changed) {
98 fireValueChange(Diffs.createValueDiff(this.value, this.value = value));
99 }
100 }
101
102 public Object getValueType() {
103 return valueType;
104 }
105
106 /**
107 * @param elementType can be <code>null</code>
108 * @return new instance with the default realm and a value of <code>null</code>
109 */
110 public static WritableValue withValueType(Object elementType) {
111 return new WritableValue(Realm.getDefault(), null, elementType);
112 }
113 }