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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.ListIterator;
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.model.event.ListChangeEvent;
import org.eclipse.jpt.utility.model.listener.ListChangeListener;
import org.eclipse.jpt.utility.model.value.ListValueModel;
/**
* This abstract class provides the infrastructure needed to wrap
* another list value model, "lazily" listen to it, and propagate
* its change notifications.
*/
public abstract class ListValueModelWrapper<E>
extends AbstractModel
{
/** The wrapped list value model. */
protected final ListValueModel<? extends E> listHolder;
/** A listener that allows us to synch with changes to the wrapped list holder. */
protected final ListChangeListener listChangeListener;
// ********** constructors **********
/**
* Construct a list value model with the specified wrapped
* list value model.
*/
protected ListValueModelWrapper(ListValueModel<? extends E> listHolder) {
super();
if (listHolder == null) {
throw new NullPointerException();
}
this.listHolder = listHolder;
this.listChangeListener = this.buildListChangeListener();
}
// ********** initialization **********
@Override
protected ChangeSupport buildChangeSupport() {
return new SingleAspectChangeSupport(this, ListChangeListener.class, ListValueModel.LIST_VALUES);
}
protected ListChangeListener buildListChangeListener() {
return new ListChangeListener() {
public void itemsAdded(ListChangeEvent event) {
ListValueModelWrapper.this.itemsAdded(event);
}
public void itemsRemoved(ListChangeEvent event) {
ListValueModelWrapper.this.itemsRemoved(event);
}
public void itemsReplaced(ListChangeEvent event) {
ListValueModelWrapper.this.itemsReplaced(event);
}
public void itemsMoved(ListChangeEvent event) {
ListValueModelWrapper.this.itemsMoved(event);
}
public void listCleared(ListChangeEvent event) {
ListValueModelWrapper.this.listCleared(event);
}
public void listChanged(ListChangeEvent event) {
ListValueModelWrapper.this.listChanged(event);
}
@Override
public String toString() {
return "list change listener";
}
};
}
// ********** extend change support **********
/**
* Extend to start listening to the nested model if necessary.
*/
@Override
public synchronized void addListChangeListener(ListChangeListener listener) {
if (this.hasNoListChangeListeners(ListValueModel.LIST_VALUES)) {
this.engageModel();
}
super.addListChangeListener(listener);
}
/**
* Extend to start listening to the nested model if necessary.
*/
@Override
public synchronized void addListChangeListener(String listName, ListChangeListener listener) {
if (listName == ListValueModel.LIST_VALUES && this.hasNoListChangeListeners(ListValueModel.LIST_VALUES)) {
this.engageModel();
}
super.addListChangeListener(listName, listener);
}
/**
* Extend to stop listening to the nested model if necessary.
*/
@Override
public synchronized void removeListChangeListener(ListChangeListener listener) {
super.removeListChangeListener(listener);
if (this.hasNoListChangeListeners(ListValueModel.LIST_VALUES)) {
this.disengageModel();
}
}
/**
* Extend to stop listening to the nested model if necessary.
*/
@Override
public synchronized void removeListChangeListener(String listName, ListChangeListener listener) {
super.removeListChangeListener(listName, listener);
if (listName == ListValueModel.LIST_VALUES && this.hasNoListChangeListeners(ListValueModel.LIST_VALUES)) {
this.disengageModel();
}
}
// ********** behavior **********
/**
* Start listening to the list holder.
*/
protected void engageModel() {
this.listHolder.addListChangeListener(ListValueModel.LIST_VALUES, this.listChangeListener);
}
/**
* Stop listening to the list holder.
*/
protected void disengageModel() {
this.listHolder.removeListChangeListener(ListValueModel.LIST_VALUES, this.listChangeListener);
}
@Override
public void toString(StringBuilder sb) {
sb.append(this.listHolder);
}
// minimize suppressed warnings
@SuppressWarnings("unchecked")
protected ListIterator<E> items(ListChangeEvent event) {
return (ListIterator<E>) event.items();
}
// minimize suppressed warnings
@SuppressWarnings("unchecked")
protected ListIterator<E> replacedItems(ListChangeEvent event) {
return (ListIterator<E>) event.replacedItems();
}
// ********** list change support **********
/**
* Items were added to the wrapped list holder;
* propagate the change notification appropriately.
*/
protected abstract void itemsAdded(ListChangeEvent event);
/**
* Items were removed from the wrapped list holder;
* propagate the change notification appropriately.
*/
protected abstract void itemsRemoved(ListChangeEvent event);
/**
* Items were replaced in the wrapped list holder;
* propagate the change notification appropriately.
*/
protected abstract void itemsReplaced(ListChangeEvent event);
/**
* Items were moved in the wrapped list holder;
* propagate the change notification appropriately.
*/
protected abstract void itemsMoved(ListChangeEvent event);
/**
* The wrapped list holder was cleared;
* propagate the change notification appropriately.
*/
protected abstract void listCleared(ListChangeEvent event);
/**
* The value of the wrapped list holder has changed;
* propagate the change notification appropriately.
*/
protected abstract void listChanged(ListChangeEvent event);
}
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