| /******************************************************************************* |
| * 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 org.eclipse.jpt.common.utility.model.Model; |
| import org.eclipse.jpt.common.utility.model.event.ChangeEvent; |
| import org.eclipse.jpt.common.utility.model.listener.ChangeListener; |
| import org.eclipse.jpt.common.utility.model.listener.SimpleChangeListener; |
| |
| /** |
| * This abstract class provides the infrastructure needed to wrap |
| * a model, "lazily" listen to it, and convert |
| * its change notifications into property value model change |
| * notifications. |
| * <p> |
| * Subclasses must override:<ul> |
| * <li>{@link #buildValue()}<p> |
| * to return the current property value, as derived from the |
| * current model |
| * </ul> |
| * Subclasses might want to override the following methods |
| * to improve performance (by not recalculating the value, if possible):<ul> |
| * <li>{@link #modelChanged(ChangeEvent event)} |
| * <li>{@link #buildChangeListener()} |
| * </ul> |
| */ |
| public abstract class ChangePropertyValueModelAdapter<T> |
| extends AbstractPropertyValueModelAdapter<T> |
| { |
| /** The wrapped model. */ |
| protected final Model model; |
| |
| /** A listener that allows us to synch with changes to the wrapped collection holder. */ |
| protected final ChangeListener changeListener; |
| |
| |
| // ********** constructor/initialization ********** |
| |
| /** |
| * Construct a property value model with the specified wrapped model. |
| */ |
| protected ChangePropertyValueModelAdapter(Model model) { |
| super(); |
| this.model = model; |
| this.changeListener = this.buildChangeListener(); |
| } |
| |
| protected ChangeListener buildChangeListener() { |
| return new SimpleChangeListener() { |
| @Override |
| protected void modelChanged(ChangeEvent event) { |
| ChangePropertyValueModelAdapter.this.modelChanged(event); |
| } |
| @Override |
| public String toString() { |
| return "change listener command"; //$NON-NLS-1$ |
| } |
| }; |
| } |
| |
| |
| // ********** behavior ********** |
| |
| /** |
| * Start listening to the model. |
| */ |
| @Override |
| protected void engageModel_() { |
| this.model.addChangeListener(this.changeListener); |
| } |
| |
| /** |
| * Stop listening to the model. |
| */ |
| @Override |
| protected void disengageModel_() { |
| this.model.removeChangeListener(this.changeListener); |
| } |
| |
| |
| // ********** change support ********** |
| |
| /** |
| * The wrapped model has changed; |
| * propagate the change notification appropriately. |
| */ |
| protected void modelChanged(@SuppressWarnings("unused") ChangeEvent event) { |
| // by default, simply recalculate the value and fire an event |
| this.propertyChanged(); |
| } |
| |
| } |