| /******************************************************************************* |
| * Copyright (c) 2007, 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 java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.ListIterator; |
| |
| import org.eclipse.jpt.common.utility.internal.iterators.ReadOnlyListIterator; |
| import org.eclipse.jpt.common.utility.model.event.CollectionAddEvent; |
| import org.eclipse.jpt.common.utility.model.event.CollectionChangeEvent; |
| import org.eclipse.jpt.common.utility.model.event.CollectionClearEvent; |
| import org.eclipse.jpt.common.utility.model.event.CollectionRemoveEvent; |
| import org.eclipse.jpt.common.utility.model.listener.CollectionChangeListener; |
| import org.eclipse.jpt.common.utility.model.value.CollectionValueModel; |
| import org.eclipse.jpt.common.utility.model.value.ListValueModel; |
| |
| /** |
| * An adapter that allows us to make a {@link CollectionValueModel} behave like |
| * a read-only {@link ListValueModel}, sorta. |
| * <p> |
| * To maintain a reasonably consistent appearance to client code, we |
| * keep an internal list somewhat in synch with the wrapped collection. |
| * <p> |
| * <strong>NB:</strong> 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. {@link #size()}, {@link #get(int)}) will be unpredictable whenever |
| * we do not have any listeners. This should not be too painful since, |
| * most likely, clients will also be listeners. |
| */ |
| public class CollectionListValueModelAdapter<E> |
| extends AbstractListValueModel |
| 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 collection value model. |
| */ |
| 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>(collectionHolder.size()); |
| // postpone building the list and listening to the underlying collection |
| // until we have listeners ourselves... |
| } |
| |
| |
| // ********** initialization ********** |
| |
| /** |
| * The wrapped collection has changed, forward an equivalent |
| * list change event to our listeners. |
| */ |
| protected CollectionChangeListener buildCollectionChangeListener() { |
| return new CollectionChangeListener() { |
| public void itemsAdded(CollectionAddEvent event) { |
| CollectionListValueModelAdapter.this.itemsAdded(event); |
| } |
| public void itemsRemoved(CollectionRemoveEvent event) { |
| CollectionListValueModelAdapter.this.itemsRemoved(event); |
| } |
| public void collectionCleared(CollectionClearEvent event) { |
| CollectionListValueModelAdapter.this.collectionCleared(event); |
| } |
| public void collectionChanged(CollectionChangeEvent event) { |
| CollectionListValueModelAdapter.this.collectionChanged(event); |
| } |
| @Override |
| public String toString() { |
| return "collection change listener"; //$NON-NLS-1$ |
| } |
| }; |
| } |
| |
| |
| // ********** 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(); |
| } |
| |
| |
| // ********** behavior ********** |
| |
| @Override |
| 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(); |
| } |
| |
| @Override |
| 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 buildList() { |
| // if the new collection is empty, do nothing |
| int size = this.collectionHolder.size(); |
| if (size != 0) { |
| this.buildList(size); |
| } |
| } |
| |
| protected void buildList(int size) { |
| this.list.ensureCapacity(size); |
| for (E each : this.collectionHolder) { |
| this.list.add(each); |
| } |
| } |
| |
| protected void itemsAdded(CollectionAddEvent event) { |
| this.addItemsToList(this.indexToAddItems(), this.getItems(event), this.list, LIST_VALUES); |
| } |
| |
| protected int indexToAddItems() { |
| return this.list.size(); |
| } |
| |
| // minimize scope of suppressed warnings |
| @SuppressWarnings("unchecked") |
| protected Iterable<E> getItems(CollectionAddEvent event) { |
| return (Iterable<E>) event.getItems(); |
| } |
| |
| protected void itemsRemoved(CollectionRemoveEvent event) { |
| this.removeItemsFromList(this.getItems(event), this.list, LIST_VALUES); |
| } |
| |
| // minimize scope of suppressed warnings |
| @SuppressWarnings("unchecked") |
| protected Iterable<E> getItems(CollectionRemoveEvent event) { |
| return (Iterable<E>) event.getItems(); |
| } |
| |
| protected void collectionCleared(@SuppressWarnings("unused") CollectionClearEvent event) { |
| this.clearList(this.list, LIST_VALUES); |
| } |
| |
| /** |
| * synchronize our internal list with the wrapped collection |
| * and fire the appropriate events |
| */ |
| protected void collectionChanged(@SuppressWarnings("unused") CollectionChangeEvent event) { |
| int size = this.collectionHolder.size(); |
| if (size == 0) { |
| if (this.list.isEmpty()) { |
| // no change |
| } else { |
| this.clearList(this.list, LIST_VALUES); |
| } |
| } else { |
| if (this.list.isEmpty()) { |
| this.buildList(size); |
| this.fireItemsAdded(LIST_VALUES, 0, this.list); |
| } else { |
| this.synchronizeList(this.buildSyncList(), this.list, LIST_VALUES); |
| } |
| } |
| } |
| |
| protected Iterable<? extends E> buildSyncList() { |
| return this.collectionHolder; |
| } |
| |
| @Override |
| public void toString(StringBuilder sb) { |
| sb.append(this.list); |
| } |
| |
| } |