| /******************************************************************************* |
| * 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.Model; |
| import org.eclipse.jpt.utility.model.event.StateChangeEvent; |
| import org.eclipse.jpt.utility.model.listener.StateChangeListener; |
| |
| /** |
| * This abstract class provides the infrastructure needed to wrap |
| * a model, "lazily" listen to it, and convert |
| * its state change notifications into property value model change |
| * notifications. |
| * |
| * Subclasses must override: |
| * - #buildValue() |
| * to return the current property value, as derived from the |
| * current model |
| * |
| * Subclasses might want to override: |
| * - #stateChanged(StateChangeEvent event) |
| * to improve performance (by not recalculating the value, if possible) |
| */ |
| public abstract class StatePropertyValueModelAdapter<T> |
| extends AspectPropertyValueModelAdapter<T> |
| { |
| /** The wrapped model. */ |
| protected final Model model; |
| |
| /** A listener that allows us to synch with changes to the wrapped model. */ |
| protected final StateChangeListener stateChangeListener; |
| |
| |
| // ********** constructor/initialization ********** |
| |
| /** |
| * Construct a property value model with the specified wrapped model. |
| */ |
| protected StatePropertyValueModelAdapter(Model model) { |
| super(); |
| this.model = model; |
| this.stateChangeListener = this.buildStateChangeListener(); |
| } |
| |
| protected StateChangeListener buildStateChangeListener() { |
| return new StateChangeListener() { |
| public void stateChanged(StateChangeEvent event) { |
| StatePropertyValueModelAdapter.this.stateChanged(event); |
| } |
| @Override |
| public String toString() { |
| return "state change listener"; |
| } |
| }; |
| } |
| |
| |
| // ********** behavior ********** |
| |
| /** |
| * Start listening to the model. |
| */ |
| @Override |
| protected void engageModel_() { |
| this.model.addStateChangeListener(this.stateChangeListener); |
| } |
| |
| /** |
| * Stop listening to the model. |
| */ |
| @Override |
| protected void disengageModel_() { |
| this.model.removeStateChangeListener(this.stateChangeListener); |
| } |
| |
| @Override |
| public void toString(StringBuilder sb) { |
| sb.append(this.model); |
| } |
| |
| |
| // ********** state change support ********** |
| |
| /** |
| * The model's state changed; |
| * propagate the change notification appropriately. |
| */ |
| protected void stateChanged(StateChangeEvent event) { |
| // by default, simply recalculate the value and fire an event |
| this.propertyChanged(); |
| } |
| |
| } |