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/*******************************************************************************
* Copyright (c) 2009, 2010 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.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import org.eclipse.jpt.utility.internal.IdentityHashBag;
import org.eclipse.jpt.utility.model.event.CollectionAddEvent;
import org.eclipse.jpt.utility.model.event.CollectionChangeEvent;
import org.eclipse.jpt.utility.model.event.CollectionClearEvent;
import org.eclipse.jpt.utility.model.event.CollectionRemoveEvent;
import org.eclipse.jpt.utility.model.event.PropertyChangeEvent;
import org.eclipse.jpt.utility.model.listener.PropertyChangeListener;
import org.eclipse.jpt.utility.model.value.CollectionValueModel;
import org.eclipse.jpt.utility.model.value.PropertyValueModel;
/**
* A <code>CompositePropertyValueModel</code> adapts a
* {@link CollectionValueModel} holding other {@link PropertyValueModel}s
* to a single {@link PropertyValueModel}.
* <p>
* Subclasses must implement:<ul>
* <li>{@link #buildValue()}<p>
* to return the current property value, as derived from the
* component values
* </ul>
* <strong>NB:</strong> The wrapped collection must not contain any duplicates
* or this class will throw an exception.
*/
public abstract class CompositePropertyValueModel<V>
extends CollectionPropertyValueModelAdapter<V>
{
/**
* Cache the component property value models so we can stop listening to
* them when they are removed from the collection value model.
*/
protected final IdentityHashBag<PropertyValueModel<?>> componentPVMs =
new IdentityHashBag<PropertyValueModel<?>>();
/**
* Listen to every property value model in the collection value model.
* If one changes, we need to re-calculate our value.
*/
protected final PropertyChangeListener propertyChangeListener;
// ********** constructors **********
/**
* Construct a property value model that is a composite of the specified
* property value models.
*/
public CompositePropertyValueModel(PropertyValueModel<?>... collection) {
this(Arrays.asList(collection));
}
/**
* Construct a property value model that is a composite of the specified
* property value models.
*/
public <E extends PropertyValueModel<?>> CompositePropertyValueModel(Collection<E> collection) {
this(new StaticCollectionValueModel<E>(collection));
}
/**
* Construct a property value model that is a composite of the specified
* property value models.
*/
public CompositePropertyValueModel(CollectionValueModel<? extends PropertyValueModel<?>> collectionModel) {
super(collectionModel);
this.propertyChangeListener = this.buildPropertyChangeListener();
}
// ********** initialization **********
protected PropertyChangeListener buildPropertyChangeListener() {
return new PropertyChangeListener() {
public void propertyChanged(PropertyChangeEvent event) {
CompositePropertyValueModel.this.propertyChanged(event);
}
@Override
public String toString() {
return "property change listener"; //$NON-NLS-1$
}
};
}
// ********** behavior **********
/**
* Subclasses can override this method if the event can be used to improve
* the performance of building a new value (e.g. some property changes may
* not necessitate the re-calculation of the value).
*/
protected void propertyChanged(@SuppressWarnings("unused") PropertyChangeEvent event) {
this.propertyChanged();
}
// ********** CollectionPropertyValueModelAdapter overrides **********
@Override
protected void engageModel_() {
super.engageModel_();
this.addComponentPVMs(this.getCollectionModel());
}
protected <E extends PropertyValueModel<?>> void addComponentPVMs(Iterable<E> pvms) {
for (PropertyValueModel<?> each : pvms) {
this.componentPVMs.add(each);
each.addPropertyChangeListener(VALUE, this.propertyChangeListener);
}
}
@Override
protected void disengageModel_() {
this.removeComponentPVMs(this.getCollectionModel());
super.disengageModel_();
}
protected <E extends PropertyValueModel<?>> void removeComponentPVMs(Iterable<E> pvms) {
for (PropertyValueModel<?> each : pvms) {
each.removePropertyChangeListener(VALUE, this.propertyChangeListener);
this.componentPVMs.remove(each);
}
}
@Override
protected void itemsAdded(CollectionAddEvent event) {
this.addComponentPVMs(this.getItems(event));
super.itemsAdded(event);
}
@Override
protected void itemsRemoved(CollectionRemoveEvent event) {
this.removeComponentPVMs(this.getItems(event));
super.itemsRemoved(event);
}
@Override
protected void collectionCleared(CollectionClearEvent event) {
this.removeAllComponentPVMs();
super.collectionCleared(event);
}
protected void removeAllComponentPVMs() {
// copy the list so we don't eat our own tail
ArrayList<PropertyValueModel<?>> copy = new ArrayList<PropertyValueModel<?>>(this.componentPVMs);
this.removeComponentPVMs(copy);
}
@Override
protected void collectionChanged(CollectionChangeEvent event) {
this.removeAllComponentPVMs();
this.addComponentPVMs(this.getCollectionModel());
super.collectionChanged(event);
}
// ********** convenience methods **********
/**
* Our constructor accepts only a {@link CollectionValueModel}{@code<? extends }{@link PropertyValueModel}{@code<?>>}.
*/
// minimize scope of suppressed warnings
@SuppressWarnings("unchecked")
protected CollectionValueModel<? extends PropertyValueModel<?>> getCollectionModel() {
return (CollectionValueModel<? extends PropertyValueModel<?>>) this.collectionModel;
}
/**
* Our constructor accepts only a {@link CollectionValueModel}{@code<? extends }{@link PropertyValueModel}{@code<?>>}.
*/
@SuppressWarnings("unchecked")
protected Iterable<? extends PropertyValueModel<?>> getItems(CollectionAddEvent event) {
return (Iterable<? extends PropertyValueModel<?>>) event.getItems();
}
/**
* Our constructor accepts only a {@link CollectionValueModel}{@code<? extends }{@link PropertyValueModel}{@code<?>>}.
*/
@SuppressWarnings("unchecked")
protected Iterable<? extends PropertyValueModel<?>> getItems(CollectionRemoveEvent event) {
return (Iterable<? extends PropertyValueModel<?>>) event.getItems();
}
}
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