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/*******************************************************************************
* Copyright (c) 2007, 2013 IBM Corporation and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* IBM Corporation - initial API and implementation
* Wind River - Pawel Piech - NPE when closing the Variables view (Bug 213719)
*******************************************************************************/
package org.eclipse.debug.internal.ui.viewers.model.provisional;
import org.eclipse.debug.internal.ui.viewers.model.ViewerAdapterService;
import org.eclipse.debug.internal.ui.viewers.model.ViewerInputUpdate;
/**
* Service to compute a viewer input from a source object
* for a given presentation context.
* <p>
* This class may be instantiated, but it not intended to be sub-classed.
* </p>
* @since 3.4
* @noextend This class is not intended to be subclassed by clients.
*/
public class ViewerInputService {
/**
* An input object which will yield a null input element.
*
* @since 3.6
*/
public final static Object NULL_INPUT = new IViewerInputProvider() {
@Override
public void update(IViewerInputUpdate update) {
update.setInputElement(null);
update.done();
}
};
// previous update request, cancelled when a new request comes in
private IViewerInputUpdate fPendingUpdate = null;
private IViewerInputRequestor fRequestor = null;
private ITreeModelViewer fViewer;
private IViewerInputRequestor fProxyRequest = new IViewerInputRequestor() {
@Override
public void viewerInputComplete(final IViewerInputUpdate update) {
synchronized (ViewerInputService.this) {
if (fPendingUpdate == update) {
fPendingUpdate = null;
}
}
fRequestor.viewerInputComplete(update);
}
};
/**
* Constructs a viewer input service for the given requester and presentation context.
*
* @param viewer for which inputs are required
* @param requestor client requesting viewer inputs
*/
public ViewerInputService(ITreeModelViewer viewer, IViewerInputRequestor requestor) {
fRequestor = requestor;
fViewer = viewer;
}
/**
* Resolves a viewer input derived from the given source object.
* Reports the result to the given this service's requester. A requester may be called back
* in the same or thread, or asynchronously in a different thread. Cancels any previous
* incomplete request from this service's requester.
*
* @param source source from which to derive a viewer input
*/
public void resolveViewerInput(Object source) {
IViewerInputProvider provdier = ViewerAdapterService.getInputProvider(source);
synchronized (this) {
// cancel any pending update
if (fPendingUpdate != null) {
fPendingUpdate.cancel();
}
fPendingUpdate = new ViewerInputUpdate(fViewer.getPresentationContext(), fViewer.getInput(), fProxyRequest, source);
}
if (provdier == null) {
fPendingUpdate.setInputElement(source);
fPendingUpdate.done();
} else {
provdier.update(fPendingUpdate);
}
}
/**
* Disposes this viewer input service, canceling any pending jobs.
*/
public synchronized void dispose() {
if (fPendingUpdate != null) {
fPendingUpdate.cancel();
fPendingUpdate = null;
}
}
}
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