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/*******************************************************************************
* Copyright (c) 2007, 2008 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.Arrays;
import java.util.Collection;
import java.util.Iterator;
import org.eclipse.jpt.utility.internal.CollectionTools;
import org.eclipse.jpt.utility.internal.iterators.EmptyIterator;
import org.eclipse.jpt.utility.model.Model;
import org.eclipse.jpt.utility.model.event.CollectionChangeEvent;
import org.eclipse.jpt.utility.model.listener.ChangeListener;
import org.eclipse.jpt.utility.model.listener.CollectionChangeListener;
import org.eclipse.jpt.utility.model.value.CollectionValueModel;
import org.eclipse.jpt.utility.model.value.PropertyValueModel;
/**
* This extension of AspectAdapter provides CollectionChange support.
* This allows us to convert a set of one or more collections into
* a single collection, VALUES.
*
* The typical subclass will override the following methods:
* #iterator_()
* at the very minimum, override this method to return an iterator on the
* subject's collection aspect; it does not need to be overridden if
* #iterator() is overridden and its behavior changed
* #size_()
* override this method to improve performance; it does not need to be overridden if
* #size() is overridden and its behavior changed
* #iterator()
* override this method only if returning an empty iterator when the
* subject is null is unacceptable
* #size()
* override this method only if returning a zero when the
* subject is null is unacceptable
*/
public abstract class CollectionAspectAdapter<S extends Model, E>
extends AspectAdapter<S>
implements CollectionValueModel<E>
{
/**
* The name of the subject's collections that we use for the value.
*/
protected final String[] collectionNames;
protected static final String[] EMPTY_COLLECTION_NAMES = new String[0];
/** A listener that listens to the subject's collection aspect. */
protected final CollectionChangeListener collectionChangeListener;
// ********** constructors **********
/**
* Construct a CollectionAspectAdapter for the specified subject
* and collection.
*/
protected CollectionAspectAdapter(String collectionName, S subject) {
this(new String[] {collectionName}, subject);
}
/**
* Construct a CollectionAspectAdapter for the specified subject
* and collections.
*/
protected CollectionAspectAdapter(String[] collectionNames, S subject) {
this(new StaticPropertyValueModel<S>(subject), collectionNames);
}
/**
* Construct a CollectionAspectAdapter for the specified subject holder
* and collections.
*/
protected CollectionAspectAdapter(PropertyValueModel<? extends S> subjectHolder, String... collectionNames) {
super(subjectHolder);
this.collectionNames = collectionNames;
this.collectionChangeListener = this.buildCollectionChangeListener();
}
/**
* Construct a CollectionAspectAdapter for the specified subject holder
* and collections.
*/
protected CollectionAspectAdapter(PropertyValueModel<? extends S> subjectHolder, Collection<String> collectionNames) {
this(subjectHolder, collectionNames.toArray(new String[collectionNames.size()]));
}
/**
* Construct a CollectionAspectAdapter for an "unchanging" collection in
* the specified subject. This is useful for a collection aspect that does not
* change for a particular subject; but the subject will change, resulting in
* a new collection.
*/
protected CollectionAspectAdapter(PropertyValueModel<? extends S> subjectHolder) {
this(subjectHolder, EMPTY_COLLECTION_NAMES);
}
// ********** initialization **********
/**
* The subject's collection aspect has changed, notify the listeners.
*/
protected CollectionChangeListener buildCollectionChangeListener() {
// transform the subject's collection change events into VALUE collection change events
return new CollectionChangeListener() {
public void itemsAdded(CollectionChangeEvent event) {
CollectionAspectAdapter.this.itemsAdded(event);
}
public void itemsRemoved(CollectionChangeEvent event) {
CollectionAspectAdapter.this.itemsRemoved(event);
}
public void collectionCleared(CollectionChangeEvent event) {
CollectionAspectAdapter.this.collectionCleared(event);
}
public void collectionChanged(CollectionChangeEvent event) {
CollectionAspectAdapter.this.collectionChanged(event);
}
@Override
public String toString() {
return "collection change listener: " + Arrays.asList(CollectionAspectAdapter.this.collectionNames);
}
};
}
// ********** CollectionValueModel implementation **********
/**
* Return the elements of the subject's collection aspect.
*/
public Iterator<E> iterator() {
return (this.subject == null) ? EmptyIterator.<E>instance() : this.iterator_();
}
/**
* Return the elements of the subject's collection aspect.
* At this point we can be sure that the subject is not null.
* @see #iterator()
*/
protected Iterator<E> iterator_() {
throw new UnsupportedOperationException();
}
/**
* Return the size of the subject's collection aspect.
*/
public int size() {
return (this.subject == null) ? 0 : this.size_();
}
/**
* Return the size of the subject's collection aspect.
* At this point we can be sure that the subject is not null.
* @see #size()
*/
protected int size_() {
return CollectionTools.size(this.iterator());
}
// ********** AspectAdapter implementation **********
@Override
protected Object getValue() {
return this.iterator();
}
@Override
protected Class<? extends ChangeListener> getListenerClass() {
return CollectionChangeListener.class;
}
@Override
protected String getListenerAspectName() {
return VALUES;
}
@Override
protected boolean hasListeners() {
return this.hasAnyCollectionChangeListeners(VALUES);
}
@Override
protected void fireAspectChange(Object oldValue, Object newValue) {
this.fireCollectionChanged(VALUES);
}
@Override
protected void engageSubject_() {
for (String collectionName : this.collectionNames) {
((Model) this.subject).addCollectionChangeListener(collectionName, this.collectionChangeListener);
}
}
@Override
protected void disengageSubject_() {
for (String collectionName : this.collectionNames) {
((Model) this.subject).removeCollectionChangeListener(collectionName, this.collectionChangeListener);
}
}
@Override
public void toString(StringBuilder sb) {
for (int i = 0; i < this.collectionNames.length; i++) {
if (i != 0) {
sb.append(", ");
}
sb.append(this.collectionNames[i]);
}
}
// ********** behavior **********
protected void itemsAdded(CollectionChangeEvent event) {
this.fireItemsAdded(event.cloneWithSource(this, VALUES));
}
protected void itemsRemoved(CollectionChangeEvent event) {
this.fireItemsRemoved(event.cloneWithSource(this, VALUES));
}
protected void collectionCleared(CollectionChangeEvent event) {
this.fireCollectionCleared(VALUES); // nothing from original event to forward
}
protected void collectionChanged(CollectionChangeEvent event) {
this.fireCollectionChanged(VALUES); // nothing from original event to forward
}
}
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