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comparison org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/SelectionProviderSingleSelectionObservableValue.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) 2005, 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 * IBM Corporation - initial API and implementation
10 * Brad Reynolds - bug 137877
11 * Brad Reynolds - bug 164653
12 * Brad Reynolds - bug 147515
13 * Ashley Cambrell - bug 198906
14 *******************************************************************************/
15
16 module org.eclipse.jface.internal.databinding.viewers.SelectionProviderSingleSelectionObservableValue;
17
18 import java.lang.all;
19
20 import org.eclipse.core.databinding.observable.Diffs;
21 import org.eclipse.core.databinding.observable.Realm;
22 import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
23 import org.eclipse.jface.util.Util;
24 import org.eclipse.jface.viewers.ISelection;
25 import org.eclipse.jface.viewers.ISelectionChangedListener;
26 import org.eclipse.jface.viewers.ISelectionProvider;
27 import org.eclipse.jface.viewers.IStructuredSelection;
28 import org.eclipse.jface.viewers.SelectionChangedEvent;
29 import org.eclipse.jface.viewers.StructuredSelection;
30
31 /**
32 * Observes single selection of an <code>ISelectionProvider</code>.
33 *
34 * @since 1.1
35 */
36 public class SelectionProviderSingleSelectionObservableValue :
37 AbstractObservableValue {
38
39 private final ISelectionProvider selectionProvider;
40
41 private bool updating = false;
42
43 private Object currentSelection;
44
45 private ISelectionChangedListener selectionChangedListener;
46
47 /**
48 * Constructs a new instance associated with the provided
49 * <code>selectionProvider</code>. In order to initialize itself properly
50 * the constructor invokes {@link #doGetValue()}. This could be dangerous
51 * for subclasses, see {@link #doGetValue()} for an explanation.
52 *
53 * @param realm
54 *
55 * @param selectionProvider
56 * @see #doGetValue()
57 */
58 public this(Realm realm,
59 ISelectionProvider selectionProvider) {
60 super(realm);
61 if (selectionProvider is null) {
62 throw new IllegalArgumentException(
63 "The 'selectionProvider' parameter is null."); //$NON-NLS-1$
64 }
65
66 this.selectionProvider = selectionProvider;
67 this.currentSelection = doGetValue();
68
69 selectionChangedListener = new class() ISelectionChangedListener {
70 public void selectionChanged(SelectionChangedEvent event) {
71 if (!updating) {
72 Object oldSelection = currentSelection;
73 currentSelection = doGetValue();
74 fireValueChange(Diffs.createValueDiff(oldSelection,
75 currentSelection));
76 }
77 }
78 };
79 selectionProvider.addSelectionChangedListener(selectionChangedListener);
80 }
81
82 /**
83 * Sets the selection to the provided <code>value</code>. Value change
84 * events are fired after selection is set in the selection provider.
85 *
86 * @param value
87 * object to set as selected, <code>null</code> if wanting to
88 * remove selection
89 */
90 public void doSetValue(Object value) {
91 try {
92 updating = true;
93
94 Object oldSelection = currentSelection;
95 selectionProvider
96 .setSelection(value is null ? StructuredSelection.EMPTY
97 : new StructuredSelection(value));
98 currentSelection = doGetValue();
99 if (!Util.equals(oldSelection, currentSelection)) {
100 fireValueChange(Diffs.createValueDiff(oldSelection,
101 currentSelection));
102 }
103 } finally {
104 updating = false;
105 }
106 }
107
108 /**
109 * Retrieves the current selection.
110 * <p>
111 * If a subclass overrides this method it must not depend upon the subclass
112 * to have been fully initialized before this method is invoked.
113 * <code>doGetValue()</code> is invoked by the
114 * {@link #SelectionProviderSingleSelectionObservableValue(Realm, ISelectionProvider) constructor}
115 * which means the subclass's constructor will not have fully executed
116 * before this method is invoked.
117 * </p>
118 *
119 * @return selection will be an instance of
120 * <code>IStructuredSelection</code> if a selection exists,
121 * <code>null</code> if no selection
122 * @see #SelectionProviderSingleSelectionObservableValue(Realm,
123 * ISelectionProvider)
124 */
125 protected Object doGetValue() {
126 ISelection selection = selectionProvider.getSelection();
127 if (null !is cast(IStructuredSelection)selection) {
128 IStructuredSelection sel = cast(IStructuredSelection) selection;
129 return sel.getFirstElement();
130 }
131
132 return null;
133 }
134
135 public Object getValueType() {
136 return null;
137 }
138
139 /*
140 * (non-Javadoc)
141 *
142 * @see org.eclipse.core.databinding.observable.value.AbstractObservableValue#dispose()
143 */
144 public synchronized void dispose() {
145 selectionProvider
146 .removeSelectionChangedListener(selectionChangedListener);
147 super.dispose();
148 }
149 }