| /******************************************************************************* |
| * 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.ArrayList; |
| import java.util.Iterator; |
| import java.util.ListIterator; |
| import org.eclipse.jpt.utility.internal.CollectionTools; |
| import org.eclipse.jpt.utility.internal.iterators.ReadOnlyListIterator; |
| 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.CollectionChangeEvent; |
| import org.eclipse.jpt.utility.model.listener.CollectionChangeListener; |
| import org.eclipse.jpt.utility.model.listener.ListChangeListener; |
| import org.eclipse.jpt.utility.model.value.CollectionValueModel; |
| import org.eclipse.jpt.utility.model.value.ListValueModel; |
| |
| /** |
| * An adapter that allows us to make a CollectionValueModel behave like |
| * a read-only ListValueModel, sorta. |
| * |
| * To maintain a reasonably consistent appearance to client code, we |
| * keep an internal list somewhat in synch with the wrapped collection. |
| * |
| * NB: Since we only listen to the wrapped collection when we have |
| * listeners ourselves and we can only stay in synch with the wrapped |
| * collection while we are listening to it, results to various methods |
| * (e.g. #size(), getItem(int)) will be unpredictable whenever |
| * we do not have any listeners. This should not be too painful since, |
| * most likely, client objects will also be listeners. |
| */ |
| public class CollectionListValueModelAdapter<E> |
| extends AbstractModel |
| implements ListValueModel<E> |
| { |
| /** The wrapped collection value model. */ |
| protected final CollectionValueModel<? extends E> collectionHolder; |
| |
| /** A listener that forwards any events fired by the collection holder. */ |
| protected final CollectionChangeListener collectionChangeListener; |
| |
| /** |
| * Our internal list, which holds the same elements as |
| * the wrapped collection, but keeps them in order. |
| */ |
| // we declare this an ArrayList so we can use #clone() and #ensureCapacity(int) |
| protected final ArrayList<E> list; |
| |
| |
| // ********** constructors ********** |
| |
| /** |
| * Wrap the specified CollectionValueModel. |
| */ |
| public CollectionListValueModelAdapter(CollectionValueModel<? extends E> collectionHolder) { |
| super(); |
| if (collectionHolder == null) { |
| throw new NullPointerException(); |
| } |
| this.collectionHolder = collectionHolder; |
| this.collectionChangeListener = this.buildCollectionChangeListener(); |
| this.list = new ArrayList<E>(); |
| // postpone building the list and listening to the underlying collection |
| // until we have listeners ourselves... |
| } |
| |
| |
| // ********** initialization ********** |
| |
| @Override |
| protected ChangeSupport buildChangeSupport() { |
| return new SingleAspectChangeSupport(this, ListChangeListener.class, LIST_VALUES); |
| } |
| |
| /** |
| * The wrapped collection has changed, forward an equivalent |
| * list change event to our listeners. |
| */ |
| protected CollectionChangeListener buildCollectionChangeListener() { |
| return new CollectionChangeListener() { |
| public void itemsAdded(CollectionChangeEvent event) { |
| CollectionListValueModelAdapter.this.itemsAdded(event); |
| } |
| public void itemsRemoved(CollectionChangeEvent event) { |
| CollectionListValueModelAdapter.this.itemsRemoved(event); |
| } |
| public void collectionCleared(CollectionChangeEvent event) { |
| CollectionListValueModelAdapter.this.collectionCleared(event); |
| } |
| public void collectionChanged(CollectionChangeEvent event) { |
| CollectionListValueModelAdapter.this.collectionChanged(event); |
| } |
| @Override |
| public String toString() { |
| return "collection change listener"; |
| } |
| }; |
| } |
| |
| |
| // ********** ListValueModel implementation ********** |
| |
| public Iterator<E> iterator() { |
| return this.listIterator(); |
| } |
| |
| public ListIterator<E> listIterator() { |
| return new ReadOnlyListIterator<E>(this.list); |
| } |
| |
| public E get(int index) { |
| return this.list.get(index); |
| } |
| |
| public int size() { |
| return this.list.size(); |
| } |
| |
| public Object[] toArray() { |
| return this.list.toArray(); |
| } |
| |
| |
| // ********** extend change support ********** |
| |
| /** |
| * Override to start listening to the collection holder if necessary. |
| */ |
| @Override |
| public void addListChangeListener(ListChangeListener listener) { |
| if (this.hasNoListeners()) { |
| this.engageModel(); |
| } |
| super.addListChangeListener(listener); |
| } |
| |
| /** |
| * Override to start listening to the collection holder if necessary. |
| */ |
| @Override |
| public void addListChangeListener(String listName, ListChangeListener listener) { |
| if (listName == LIST_VALUES && this.hasNoListeners()) { |
| this.engageModel(); |
| } |
| super.addListChangeListener(listName, listener); |
| } |
| |
| /** |
| * Override to stop listening to the collection holder if appropriate. |
| */ |
| @Override |
| public void removeListChangeListener(ListChangeListener listener) { |
| super.removeListChangeListener(listener); |
| if (this.hasNoListeners()) { |
| this.disengageModel(); |
| } |
| } |
| |
| /** |
| * Override to stop listening to the collection holder if appropriate. |
| */ |
| @Override |
| public void removeListChangeListener(String listName, ListChangeListener listener) { |
| super.removeListChangeListener(listName, listener); |
| if (listName == LIST_VALUES && this.hasNoListeners()) { |
| this.disengageModel(); |
| } |
| } |
| |
| |
| // ********** queries ********** |
| |
| protected boolean hasListeners() { |
| return this.hasAnyListChangeListeners(LIST_VALUES); |
| } |
| |
| protected boolean hasNoListeners() { |
| return ! this.hasListeners(); |
| } |
| |
| /** |
| * Return the index of the specified item, using object |
| * identity instead of equality. |
| */ |
| protected int lastIdentityIndexOf(Object o) { |
| return this.lastIdentityIndexOf(o, this.list.size()); |
| } |
| |
| /** |
| * Return the last index of the specified item, starting just before the |
| * the specified endpoint, and using object identity instead of equality. |
| */ |
| protected int lastIdentityIndexOf(Object o, int end) { |
| for (int i = end; i-- > 0; ) { |
| if (this.list.get(i) == o) { |
| return i; |
| } |
| } |
| return -1; |
| } |
| |
| |
| // ********** behavior ********** |
| |
| protected void buildList() { |
| Iterator<? extends E> stream = this.collectionHolder.iterator(); |
| // if the new collection is empty, do nothing |
| if (stream.hasNext()) { |
| this.list.ensureCapacity(this.collectionHolder.size()); |
| while (stream.hasNext()) { |
| this.list.add(stream.next()); |
| } |
| this.postBuildList(); |
| } |
| } |
| |
| /** |
| * Allow subclasses to manipulate the internal list before |
| * sending out change notification. |
| */ |
| protected void postBuildList() { |
| // the default is to do nothing... |
| } |
| |
| protected void engageModel() { |
| this.collectionHolder.addCollectionChangeListener(CollectionValueModel.VALUES, this.collectionChangeListener); |
| // synch our list *after* we start listening to the collection holder, |
| // since its value might change when a listener is added |
| this.buildList(); |
| } |
| |
| protected void disengageModel() { |
| this.collectionHolder.removeCollectionChangeListener(CollectionValueModel.VALUES, this.collectionChangeListener); |
| // clear out the list when we are not listening to the collection holder |
| this.list.clear(); |
| } |
| |
| protected void itemsAdded(CollectionChangeEvent e) { |
| this.addItemsToList(this.indexToAddItems(), CollectionTools.list(this.items(e)), this.list, LIST_VALUES); |
| } |
| |
| protected int indexToAddItems() { |
| return this.list.size(); |
| } |
| |
| @SuppressWarnings("unchecked") |
| protected Iterator<E> items(CollectionChangeEvent e) { |
| return (Iterator<E>) e.items(); |
| } |
| |
| protected void itemsRemoved(CollectionChangeEvent e) { |
| // we have to remove the items individually, |
| // since they are probably not in sequence |
| for (Iterator<E> stream = this.items(e); stream.hasNext(); ) { |
| this.removeItemFromList(this.lastIdentityIndexOf(stream.next()), this.list, LIST_VALUES); |
| } |
| } |
| |
| protected void collectionCleared(CollectionChangeEvent e) { |
| this.clearList(this.list, LIST_VALUES); |
| } |
| |
| /** |
| * synchronize our internal list with the wrapped collection |
| * and fire the appropriate events |
| */ |
| protected void collectionChanged(CollectionChangeEvent e) { |
| // put in empty check so we don't fire events unnecessarily |
| if ( ! this.list.isEmpty()) { |
| @SuppressWarnings("unchecked") |
| ArrayList<E> removedItems = (ArrayList<E>) this.list.clone(); |
| this.list.clear(); |
| this.fireItemsRemoved(LIST_VALUES, 0, removedItems); |
| } |
| |
| this.buildList(); |
| // put in empty check so we don't fire events unnecessarily |
| if ( ! this.list.isEmpty()) { |
| this.fireItemsAdded(LIST_VALUES, 0, this.list); |
| } |
| } |
| |
| @Override |
| public void toString(StringBuilder sb) { |
| sb.append(this.collectionHolder); |
| } |
| |
| } |