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1 /*******************************************************************************
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2 * Copyright (c) 2005, 2008 IBM Corporation and others.
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3 * All rights reserved. This program and the accompanying materials
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4 * are made available under the terms of the Eclipse Public License v1.0
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5 * which accompanies this distribution, and is available at
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6 * http://www.eclipse.org/legal/epl-v10.html
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7 *
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8 * Contributors:
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9 * IBM Corporation - initial API and implementation
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10 * Brad Reynolds - bug 137877
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11 * Brad Reynolds - bug 164653
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12 * Brad Reynolds - bug 147515
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13 * Ashley Cambrell - bug 198906
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14 *******************************************************************************/
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15
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16 module org.eclipse.jface.internal.databinding.viewers.SelectionProviderSingleSelectionObservableValue;
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17
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18 import java.lang.all;
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19
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20 import org.eclipse.core.databinding.observable.Diffs;
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21 import org.eclipse.core.databinding.observable.Realm;
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22 import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
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23 import org.eclipse.jface.util.Util;
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24 import org.eclipse.jface.viewers.ISelection;
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25 import org.eclipse.jface.viewers.ISelectionChangedListener;
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26 import org.eclipse.jface.viewers.ISelectionProvider;
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27 import org.eclipse.jface.viewers.IStructuredSelection;
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28 import org.eclipse.jface.viewers.SelectionChangedEvent;
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29 import org.eclipse.jface.viewers.StructuredSelection;
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30
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31 /**
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32 * Observes single selection of an <code>ISelectionProvider</code>.
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33 *
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34 * @since 1.1
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35 */
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36 public class SelectionProviderSingleSelectionObservableValue :
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37 AbstractObservableValue {
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38
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39 private final ISelectionProvider selectionProvider;
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40
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41 private bool updating = false;
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42
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43 private Object currentSelection;
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44
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45 private ISelectionChangedListener selectionChangedListener;
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46
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47 /**
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48 * Constructs a new instance associated with the provided
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49 * <code>selectionProvider</code>. In order to initialize itself properly
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50 * the constructor invokes {@link #doGetValue()}. This could be dangerous
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51 * for subclasses, see {@link #doGetValue()} for an explanation.
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52 *
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53 * @param realm
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54 *
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55 * @param selectionProvider
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56 * @see #doGetValue()
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57 */
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58 public this(Realm realm,
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59 ISelectionProvider selectionProvider) {
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60 super(realm);
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61 if (selectionProvider is null) {
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62 throw new IllegalArgumentException(
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63 "The 'selectionProvider' parameter is null."); //$NON-NLS-1$
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64 }
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65
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66 this.selectionProvider = selectionProvider;
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67 this.currentSelection = doGetValue();
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68
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69 selectionChangedListener = new class() ISelectionChangedListener {
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70 public void selectionChanged(SelectionChangedEvent event) {
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71 if (!updating) {
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72 Object oldSelection = currentSelection;
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73 currentSelection = doGetValue();
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74 fireValueChange(Diffs.createValueDiff(oldSelection,
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75 currentSelection));
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76 }
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77 }
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78 };
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79 selectionProvider.addSelectionChangedListener(selectionChangedListener);
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80 }
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81
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82 /**
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83 * Sets the selection to the provided <code>value</code>. Value change
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84 * events are fired after selection is set in the selection provider.
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85 *
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86 * @param value
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87 * object to set as selected, <code>null</code> if wanting to
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88 * remove selection
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89 */
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90 public void doSetValue(Object value) {
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91 try {
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92 updating = true;
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93
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94 Object oldSelection = currentSelection;
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95 selectionProvider
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96 .setSelection(value is null ? StructuredSelection.EMPTY
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97 : new StructuredSelection(value));
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98 currentSelection = doGetValue();
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99 if (!Util.equals(oldSelection, currentSelection)) {
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100 fireValueChange(Diffs.createValueDiff(oldSelection,
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101 currentSelection));
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102 }
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103 } finally {
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104 updating = false;
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105 }
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106 }
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107
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108 /**
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109 * Retrieves the current selection.
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110 * <p>
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111 * If a subclass overrides this method it must not depend upon the subclass
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112 * to have been fully initialized before this method is invoked.
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113 * <code>doGetValue()</code> is invoked by the
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114 * {@link #SelectionProviderSingleSelectionObservableValue(Realm, ISelectionProvider) constructor}
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115 * which means the subclass's constructor will not have fully executed
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116 * before this method is invoked.
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117 * </p>
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118 *
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119 * @return selection will be an instance of
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120 * <code>IStructuredSelection</code> if a selection exists,
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121 * <code>null</code> if no selection
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122 * @see #SelectionProviderSingleSelectionObservableValue(Realm,
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123 * ISelectionProvider)
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124 */
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125 protected Object doGetValue() {
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126 ISelection selection = selectionProvider.getSelection();
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127 if (null !is cast(IStructuredSelection)selection) {
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128 IStructuredSelection sel = cast(IStructuredSelection) selection;
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129 return sel.getFirstElement();
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130 }
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131
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132 return null;
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133 }
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134
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135 public Object getValueType() {
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136 return null;
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137 }
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138
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139 /*
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140 * (non-Javadoc)
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141 *
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142 * @see org.eclipse.core.databinding.observable.value.AbstractObservableValue#dispose()
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143 */
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144 public synchronized void dispose() {
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145 selectionProvider
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146 .removeSelectionChangedListener(selectionChangedListener);
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147 super.dispose();
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148 }
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149 }
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