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1 /*******************************************************************************
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2 * Copyright (c) 2007, 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 * Boris Bokowski, IBM Corporation - initial API and implementation
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10 * Matthew Hall - bug 212468
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11 *******************************************************************************/
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12 module org.eclipse.core.internal.databinding.observable.StalenessObservableValue;
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13
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14 import java.lang.all;
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15
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16 import org.eclipse.core.databinding.observable.ChangeEvent;
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17 import org.eclipse.core.databinding.observable.Diffs;
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18 import org.eclipse.core.databinding.observable.IChangeListener;
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19 import org.eclipse.core.databinding.observable.IObservable;
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20 import org.eclipse.core.databinding.observable.IStaleListener;
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21 import org.eclipse.core.databinding.observable.StaleEvent;
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22 import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
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23
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24 /**
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25 * An observable value that tracks the staleness of an {@link IObservable}.
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26 *
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27 * @since 1.1
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28 */
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29 public class StalenessObservableValue : AbstractObservableValue {
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30
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31 private class MyListener : IChangeListener, IStaleListener {
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32 public void handleChange(ChangeEvent event) {
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33 if (stale && !event.getObservable().isStale()) {
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34 stale = false;
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35 fireValueChange(Diffs.createValueDiff(Boolean.TRUE,
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36 Boolean.FALSE));
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37 }
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38 }
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39
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40 public void handleStale(StaleEvent staleEvent) {
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41 if (!stale) {
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42 stale = true;
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43 fireValueChange(Diffs.createValueDiff(Boolean.FALSE,
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44 Boolean.TRUE));
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45 }
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46 }
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47 }
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48
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49 private IObservable tracked;
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50 private bool stale;
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51 private MyListener listener = new MyListener();
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52
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53 /**
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54 * Constructs a StalenessObservableValue that tracks the staleness of the
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55 * given {@link IObservable}.
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56 *
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57 * @param observable
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58 * the observable to track
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59 */
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60 public this(IObservable observable) {
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61 super(observable.getRealm());
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62 this.tracked = observable;
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63 this.stale = observable.isStale();
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64 tracked.addChangeListener(listener);
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65 tracked.addStaleListener(listener);
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66 }
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67
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68 protected Object doGetValue() {
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69 return tracked.isStale() ? Boolean.TRUE : Boolean.FALSE;
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70 }
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71
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72 public Object getValueType() {
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73 return Boolean.TYPE;
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74 }
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75
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76 public synchronized void dispose() {
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77 if (tracked !is null) {
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78 tracked.removeChangeListener(listener);
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79 tracked.removeStaleListener(listener);
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80 tracked = null;
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81 listener = null;
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82 }
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83 super.dispose();
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84 }
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85
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86 }
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