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/*******************************************************************************
* 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.Iterator;
import org.eclipse.jpt.utility.internal.iterators.EmptyIterator;
import org.eclipse.jpt.utility.internal.model.Model;
import org.eclipse.jpt.utility.internal.model.event.TreeChangeEvent;
import org.eclipse.jpt.utility.internal.model.listener.TreeChangeListener;
/**
* This extension of PropertyAdapter provides TreeChange support.
*
* The typical subclass will override the following methods:
* #getValueFromSubject()
* 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
* #getValue() is overridden and its behavior changed
* #addNode(Object[], Object) and #removeNode(Object[])
* override these methods if the client code needs to *change* the contents of
* the subject's tree aspect; oftentimes, though, the client code
* (e.g. UI) will need only to *get* the value
* #getValue()
* override this method only if returning an empty iterator when the
* subject is null is unacceptable
*/
public abstract class TreeAspectAdapter
extends AspectAdapter
implements TreeValueModel
{
/**
* The name of the subject's tree that we use for the value.
*/
protected String treeName;
/** A listener that listens to the subject's tree aspect. */
protected TreeChangeListener treeChangeListener;
// ********** constructors **********
/**
* Construct a TreeAspectAdapter for the specified subject
* and tree.
*/
protected TreeAspectAdapter(String treeName, Model subject) {
super(subject);
this.treeName = treeName;
}
/**
* Construct a TreeAspectAdapter for the specified subject holder
* and tree.
*/
protected TreeAspectAdapter(ValueModel subjectHolder, String treeName) {
super(subjectHolder);
this.treeName = treeName;
}
// ********** initialization **********
@Override
protected void initialize() {
super.initialize();
this.treeChangeListener = this.buildTreeChangeListener();
}
/**
* The subject's tree aspect has changed, notify the listeners.
*/
protected TreeChangeListener buildTreeChangeListener() {
// transform the subject's tree change events into VALUE tree change events
return new TreeChangeListener() {
public void nodeAdded(TreeChangeEvent e) {
TreeAspectAdapter.this.nodeAdded(e);
}
public void nodeRemoved(TreeChangeEvent e) {
TreeAspectAdapter.this.nodeRemoved(e);
}
public void treeCleared(TreeChangeEvent e) {
TreeAspectAdapter.this.treeCleared(e);
}
public void treeChanged(TreeChangeEvent e) {
TreeAspectAdapter.this.treeChanged(e);
}
@Override
public String toString() {
return "tree change listener: " + TreeAspectAdapter.this.treeName;
}
};
}
// ********** ValueModel implementation **********
/**
* Return the value of the subject's tree aspect.
* This should be an *iterator* on the tree.
*/
public Object getValue() {
if (this.subject == null) {
return EmptyIterator.instance();
}
return this.getValueFromSubject();
}
/**
* Return the value of the subject's tree aspect.
* This should be an *iterator* on the tree.
* At this point we can be sure that the subject is not null.
* @see #getValue()
*/
protected Iterator getValueFromSubject() { // private-protected
throw new UnsupportedOperationException();
}
// ********** TreeValueModel implementation **********
/**
* Insert the specified node in the subject's tree aspect.
*/
public void addNode(Object[] parentPath, Object node) {
throw new UnsupportedOperationException();
}
/**
* Remove the specified node from the subject's tree aspect.
*/
public void removeNode(Object[] path) {
throw new UnsupportedOperationException();
}
// ********** AspectAdapter implementation **********
@Override
protected boolean hasListeners() {
return this.hasAnyTreeChangeListeners(VALUE);
}
@Override
protected void fireAspectChange(Object oldValue, Object newValue) {
this.fireTreeChanged(VALUE);
}
@Override
protected void engageNonNullSubject() {
((Model) this.subject).addTreeChangeListener(this.treeName, this.treeChangeListener);
}
@Override
protected void disengageNonNullSubject() {
((Model) this.subject).removeTreeChangeListener(this.treeName, this.treeChangeListener);
}
@Override
public void toString(StringBuilder sb) {
sb.append(this.treeName);
}
// ********** behavior **********
protected void nodeAdded(TreeChangeEvent e) {
this.fireNodeAdded(VALUE, e.path());
}
protected void nodeRemoved(TreeChangeEvent e) {
this.fireNodeRemoved(VALUE, e.path());
}
protected void treeCleared(TreeChangeEvent e) {
this.fireTreeCleared(VALUE);
}
protected void treeChanged(TreeChangeEvent e) {
this.fireTreeChanged(VALUE, e.path());
}
}
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