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/*******************************************************************************
* Copyright (c) 2009 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.common.utility.internal.model.value;
import java.util.Collection;
import java.util.EventListener;
import java.util.Iterator;
import org.eclipse.jpt.common.utility.internal.CollectionTools;
import org.eclipse.jpt.common.utility.internal.iterators.EmptyIterator;
import org.eclipse.jpt.common.utility.model.listener.TreeChangeListener;
import org.eclipse.jpt.common.utility.model.value.PropertyValueModel;
import org.eclipse.jpt.common.utility.model.value.TreeValueModel;
/**
* This {@link AspectAdapter} provides basic tree change support.
* This converts an "aspect" (as defined by subclasses) into
* a single {@link #NODES} tree.
* <p>
* The typical subclass will override the following methods:<ul>
* <li>{@link #engageSubject_()}<p>
* implement this method to add the appropriate listener to the subject
* <li>{@link #disengageSubject_()}<p>
* implement this method to remove the appropriate listener from the subject
* <li>{@link #nodes_()}<p>
* at the very minimum, override this method to return an iterator
* on the subject's tree aspect; it does not need to be overridden if
* {@link #nodes()} is overridden and its behavior changed
* <li>{@link #nodes()}<p>
* override this method only if returning an empty iterator when the
* subject is null is unacceptable
* </ul>
* To notify listeners, subclasses can call {@link #treeChanged()}
* whenever the aspect has changed.
*/
public abstract class AspectTreeValueModelAdapter<S, E>
extends AspectAdapter<S>
implements TreeValueModel<E>
{
// ********** constructors **********
/**
* Construct a tree value model adapter for an aspect of the
* specified subject.
*/
protected AspectTreeValueModelAdapter(PropertyValueModel<? extends S> subjectHolder) {
super(subjectHolder);
}
// ********** TreeValueModel implementation **********
/**
* Return the nodes of the subject's tree aspect.
*/
public Iterator<E> nodes() {
return (this.subject == null) ? EmptyIterator.<E>instance() : this.nodes_();
}
/**
* Return the nodes of the subject's tree aspect.
* At this point we can be sure the subject is not null.
* @see #nodes()
*/
protected Iterator<E> nodes_() {
throw new RuntimeException("This method was not overridden."); //$NON-NLS-1$
}
// ********** AspectAdapter implementation **********
@Override
protected Object getValue() {
return this.buildValueCollection();
}
@Override
protected Class<? extends EventListener> getListenerClass() {
return TreeChangeListener.class;
}
@Override
protected String getListenerAspectName() {
return NODES;
}
@Override
protected boolean hasListeners() {
return this.hasAnyTreeChangeListeners(NODES);
}
@Override
protected void fireAspectChanged(Object oldValue, Object newValue) {
@SuppressWarnings("unchecked") Collection<E> newNodes = (Collection<E>) newValue;
this.fireTreeChanged(NODES, newNodes);
}
protected void treeChanged() {
this.fireTreeChanged(NODES, this.buildValueCollection());
}
protected Collection<E> buildValueCollection() {
return CollectionTools.collection(this.nodes());
}
@Override
public void toString(StringBuilder sb) {
sb.append(this.buildValueCollection());
}
}
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