Mercurial > projects > dwt2
diff org.eclipse.core.databinding/src/org/eclipse/core/internal/databinding/observable/StalenessObservableValue.d @ 78:0a55d2d5a946
Added file for databinding
author | Frank Benoit <benoit@tionex.de> |
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date | Tue, 14 Apr 2009 11:35:29 +0200 |
parents | |
children | 6be48cf9f95c |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/org.eclipse.core.databinding/src/org/eclipse/core/internal/databinding/observable/StalenessObservableValue.d Tue Apr 14 11:35:29 2009 +0200 @@ -0,0 +1,86 @@ +/******************************************************************************* + * Copyright (c) 2007, 2008 IBM Corporation and others. + * All rights reserved. This program and the accompanying materials + * are made available under the terms of the Eclipse Public License v1.0 + * which accompanies this distribution, and is available at + * http://www.eclipse.org/legal/epl-v10.html + * + * Contributors: + * Boris Bokowski, IBM Corporation - initial API and implementation + * Matthew Hall - bug 212468 + *******************************************************************************/ +module org.eclipse.core.internal.databinding.observable.StalenessObservableValue; + +import java.lang.all; + +import org.eclipse.core.databinding.observable.ChangeEvent; +import org.eclipse.core.databinding.observable.Diffs; +import org.eclipse.core.databinding.observable.IChangeListener; +import org.eclipse.core.databinding.observable.IObservable; +import org.eclipse.core.databinding.observable.IStaleListener; +import org.eclipse.core.databinding.observable.StaleEvent; +import org.eclipse.core.databinding.observable.value.AbstractObservableValue; + +/** + * An observable value that tracks the staleness of an {@link IObservable}. + * + * @since 1.1 + */ +public class StalenessObservableValue : AbstractObservableValue { + + private class MyListener : IChangeListener, IStaleListener { + public void handleChange(ChangeEvent event) { + if (stale && !event.getObservable().isStale()) { + stale = false; + fireValueChange(Diffs.createValueDiff(Boolean.TRUE, + Boolean.FALSE)); + } + } + + public void handleStale(StaleEvent staleEvent) { + if (!stale) { + stale = true; + fireValueChange(Diffs.createValueDiff(Boolean.FALSE, + Boolean.TRUE)); + } + } + } + + private IObservable tracked; + private bool stale; + private MyListener listener = new MyListener(); + + /** + * Constructs a StalenessObservableValue that tracks the staleness of the + * given {@link IObservable}. + * + * @param observable + * the observable to track + */ + public this(IObservable observable) { + super(observable.getRealm()); + this.tracked = observable; + this.stale = observable.isStale(); + tracked.addChangeListener(listener); + tracked.addStaleListener(listener); + } + + protected Object doGetValue() { + return tracked.isStale() ? Boolean.TRUE : Boolean.FALSE; + } + + public Object getValueType() { + return Boolean.TYPE; + } + + public synchronized void dispose() { + if (tracked !is null) { + tracked.removeChangeListener(listener); + tracked.removeStaleListener(listener); + tracked = null; + listener = null; + } + super.dispose(); + } + +}