| /******************************************************************************* |
| * Copyright (c) 2007 Oracle. 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: |
| * Oracle - initial API and implementation |
| ******************************************************************************/ |
| package org.eclipse.jpt.utility.internal.model.value; |
| |
| import java.util.Collection; |
| import java.util.Iterator; |
| |
| import org.eclipse.jpt.utility.internal.model.AbstractModel; |
| import org.eclipse.jpt.utility.internal.model.ChangeSupport; |
| import org.eclipse.jpt.utility.internal.model.SingleAspectChangeSupport; |
| import org.eclipse.jpt.utility.internal.model.event.CollectionChangeEvent; |
| import org.eclipse.jpt.utility.internal.model.listener.CollectionChangeListener; |
| |
| /** |
| * This abstract class provides the infrastructure needed to wrap |
| * another collection value model, "lazily" listen to it, and propagate |
| * its change notifications. |
| */ |
| public abstract class CollectionValueModelWrapper |
| extends AbstractModel |
| implements CollectionValueModel |
| { |
| |
| /** The wrapped collection value model. */ |
| protected final CollectionValueModel collectionHolder; |
| |
| /** A listener that allows us to synch with changes to the wrapped collection holder. */ |
| protected final CollectionChangeListener collectionChangeListener; |
| |
| |
| // ********** constructors ********** |
| |
| /** |
| * Construct a collection value model with the specified wrapped |
| * collection value model. |
| */ |
| protected CollectionValueModelWrapper(CollectionValueModel collectionHolder) { |
| super(); |
| this.collectionHolder = collectionHolder; |
| this.collectionChangeListener = this.buildCollectionChangeListener(); |
| } |
| |
| |
| // ********** initialization ********** |
| |
| @Override |
| protected ChangeSupport buildChangeSupport() { |
| return new SingleAspectChangeSupport(this, CollectionChangeListener.class, VALUES); |
| } |
| |
| protected CollectionChangeListener buildCollectionChangeListener() { |
| return new CollectionChangeListener() { |
| public void itemsAdded(CollectionChangeEvent e) { |
| CollectionValueModelWrapper.this.itemsAdded(e); |
| } |
| public void itemsRemoved(CollectionChangeEvent e) { |
| CollectionValueModelWrapper.this.itemsRemoved(e); |
| } |
| public void collectionCleared(CollectionChangeEvent e) { |
| CollectionValueModelWrapper.this.collectionCleared(e); |
| } |
| public void collectionChanged(CollectionChangeEvent e) { |
| CollectionValueModelWrapper.this.collectionChanged(e); |
| } |
| @Override |
| public String toString() { |
| return "collection change listener"; |
| } |
| }; |
| } |
| |
| |
| // ********** extend change support ********** |
| |
| /** |
| * Extend to start listening to the nested model if necessary. |
| */ |
| @Override |
| public synchronized void addCollectionChangeListener(CollectionChangeListener listener) { |
| if (this.hasNoCollectionChangeListeners(VALUES)) { |
| this.engageModel(); |
| } |
| super.addCollectionChangeListener(listener); |
| } |
| |
| /** |
| * Extend to start listening to the nested model if necessary. |
| */ |
| @Override |
| public synchronized void addCollectionChangeListener(String collectionName, CollectionChangeListener listener) { |
| if (collectionName == VALUES && this.hasNoCollectionChangeListeners(VALUES)) { |
| this.engageModel(); |
| } |
| super.addCollectionChangeListener(collectionName, listener); |
| } |
| |
| /** |
| * Extend to stop listening to the nested model if necessary. |
| */ |
| @Override |
| public synchronized void removeCollectionChangeListener(CollectionChangeListener listener) { |
| super.removeCollectionChangeListener(listener); |
| if (this.hasNoCollectionChangeListeners(VALUES)) { |
| this.disengageModel(); |
| } |
| } |
| |
| /** |
| * Extend to stop listening to the nested model if necessary. |
| */ |
| @Override |
| public synchronized void removeCollectionChangeListener(String collectionName, CollectionChangeListener listener) { |
| super.removeCollectionChangeListener(collectionName, listener); |
| if (collectionName == VALUES && this.hasNoCollectionChangeListeners(VALUES)) { |
| this.disengageModel(); |
| } |
| } |
| |
| |
| // ********** behavior ********** |
| |
| /** |
| * Start listening to the collection holder. |
| */ |
| protected void engageModel() { |
| this.collectionHolder.addCollectionChangeListener(VALUES, this.collectionChangeListener); |
| } |
| |
| /** |
| * Stop listening to the collection holder. |
| */ |
| protected void disengageModel() { |
| this.collectionHolder.removeCollectionChangeListener(VALUES, this.collectionChangeListener); |
| } |
| |
| @Override |
| public void toString(StringBuilder sb) { |
| sb.append(this.collectionHolder); |
| } |
| |
| |
| // ********** collection change support ********** |
| |
| /** |
| * Items were added to the wrapped collection holder; |
| * propagate the change notification appropriately. |
| */ |
| protected abstract void itemsAdded(CollectionChangeEvent e); |
| |
| /** |
| * Items were removed from the wrapped collection holder; |
| * propagate the change notification appropriately. |
| */ |
| protected abstract void itemsRemoved(CollectionChangeEvent e); |
| |
| /** |
| * The wrapped collection holder was cleared; |
| * propagate the change notification appropriately. |
| */ |
| protected abstract void collectionCleared(CollectionChangeEvent e); |
| |
| /** |
| * The value of the wrapped collection holder has changed; |
| * propagate the change notification appropriately. |
| */ |
| protected abstract void collectionChanged(CollectionChangeEvent e); |
| |
| } |