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/*******************************************************************************
* Copyright (c) 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 org.eclipse.jpt.utility.model.event.TreeChangeEvent;
import org.eclipse.jpt.utility.model.listener.TreeChangeListener;
import org.eclipse.jpt.utility.model.value.TreeValueModel;
/**
* This abstract class provides the infrastructure needed to wrap
* a tree value model, "lazily" listen to it, and convert
* its change notifications into property value model change
* notifications.
*
* Subclasses must override:
* - #buildValue()
* to return the current property value, as derived from the
* current collection value
*
* Subclasses might want to override:
* - #stateChanged(StateChangeEvent event)
* to improve performance (by not recalculating the value, if possible)
*/
public abstract class TreePropertyValueModelAdapter<T>
extends AspectPropertyValueModelAdapter<T>
{
/** The wrapped tree value model. */
protected final TreeValueModel<?> treeHolder;
/** A listener that allows us to synch with changes to the wrapped tree holder. */
protected final TreeChangeListener treeChangeListener;
// ********** constructor/initialization **********
/**
* Construct a property value model with the specified wrapped
* tree value model.
*/
protected TreePropertyValueModelAdapter(TreeValueModel<?> treeHolder) {
super();
this.treeHolder = treeHolder;
this.treeChangeListener = this.buildTreeChangeListener();
}
protected TreeChangeListener buildTreeChangeListener() {
return new TreeChangeListener() {
public void nodeAdded(TreeChangeEvent event) {
TreePropertyValueModelAdapter.this.nodeAdded(event);
}
public void nodeRemoved(TreeChangeEvent event) {
TreePropertyValueModelAdapter.this.nodeRemoved(event);
}
public void treeCleared(TreeChangeEvent event) {
TreePropertyValueModelAdapter.this.treeCleared(event);
}
public void treeChanged(TreeChangeEvent event) {
TreePropertyValueModelAdapter.this.treeChanged(event);
}
@Override
public String toString() {
return "tree change listener";
}
};
}
// ********** behavior **********
/**
* Start listening to the tree holder.
*/
@Override
protected void engageModel_() {
this.treeHolder.addTreeChangeListener(this.treeChangeListener);
}
/**
* Stop listening to the tree holder.
*/
@Override
protected void disengageModel_() {
this.treeHolder.removeTreeChangeListener(this.treeChangeListener);
}
@Override
public void toString(StringBuilder sb) {
sb.append(this.treeHolder);
}
// ********** state change support **********
/**
* Nodes were added to the wrapped tree holder;
* propagate the change notification appropriately.
*/
protected void nodeAdded(TreeChangeEvent event) {
// by default, simply recalculate the value and fire an event
this.propertyChanged();
}
/**
* Nodes were removed from the wrapped tree holder;
* propagate the change notification appropriately.
*/
protected void nodeRemoved(TreeChangeEvent event) {
// by default, simply recalculate the value and fire an event
this.propertyChanged();
}
/**
* The wrapped tree holder was cleared;
* propagate the change notification appropriately.
*/
protected void treeCleared(TreeChangeEvent event) {
// by default, simply recalculate the value and fire an event
this.propertyChanged();
}
/**
* The wrapped tree holder changed;
* propagate the change notification appropriately.
*/
protected void treeChanged(TreeChangeEvent event) {
// by default, simply recalculate the value and fire an event
this.propertyChanged();
}
}
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