bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/viewers/ObservableSetTreeContentProvider.java

/*******************************************************************************
 * Copyright (c) 2008 Matthew Hall and others.
 * 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:
 *     Matthew Hall - initial API and implementation (bug 207858)
 *     Matthew Hall - bug 226765
 *******************************************************************************/

package org.eclipse.jface.databinding.viewers;

import java.util.Iterator;
import java.util.Set;

import org.eclipse.core.databinding.observable.IObservableCollection;
import org.eclipse.core.databinding.observable.IObservablesListener;
import org.eclipse.core.databinding.observable.masterdetail.IObservableFactory;
import org.eclipse.core.databinding.observable.set.IObservableSet;
import org.eclipse.core.databinding.observable.set.ISetChangeListener;
import org.eclipse.core.databinding.observable.set.SetChangeEvent;
import org.eclipse.jface.internal.databinding.viewers.ObservableCollectionTreeContentProvider;
import org.eclipse.jface.viewers.AbstractTreeViewer;
import org.eclipse.jface.viewers.ITreeContentProvider;
import org.eclipse.jface.viewers.Viewer;

/**
 * An {@link ITreeContentProvider} for use with an {@link AbstractTreeViewer},
 * which uses the provided {@link IObservableFactory set factory} to obtain the
 * elements of a tree. Objects of this class listen for changes to each
 * {@link IObservableSet} created by the factory, and will insert and remove
 * viewer elements to reflect the observed changes.
 * 
 * <p>
 * This class is not intended to be subclassed by clients.
 * 
 * @since 1.2
 */
public class ObservableSetTreeContentProvider implements ITreeContentProvider {
	private final ObservableCollectionTreeContentProvider impl;

	private static class Impl extends ObservableCollectionTreeContentProvider {
		Impl(IObservableFactory setFactory,
				TreeStructureAdvisor structureAdvisor) {
			super(setFactory, structureAdvisor);
		}

		private class SetChangeListener implements ISetChangeListener {
			final Object parentElement;

			public SetChangeListener(Object parentElement) {
				this.parentElement = parentElement;
			}

			public void handleSetChange(SetChangeEvent event) {
				if (isViewerDisposed())
					return;

				Set removals = event.diff.getRemovals();
				if (!removals.isEmpty()) {
					viewerUpdater.remove(parentElement, removals.toArray());
					for (Iterator iterator = removals.iterator(); iterator
							.hasNext();) {
						Object child = iterator.next();
						TreeNode childNode = getExistingNode(child);
						if (childNode != null)
							childNode.removeParent(parentElement);
					}
				}

				Set additions = event.diff.getAdditions();
				if (!additions.isEmpty()) {
					for (Iterator iterator = additions.iterator(); iterator
							.hasNext();) {
						Object child = iterator.next();
						getOrCreateNode(child).addParent(parentElement);
					}
					viewerUpdater.add(parentElement, additions.toArray());
				}
			}
		}

		protected IObservablesListener createCollectionChangeListener(
				Object parentElement) {
			return new SetChangeListener(parentElement);
		}

		protected void addCollectionChangeListener(
				IObservableCollection collection, IObservablesListener listener) {
			IObservableSet set = (IObservableSet) collection;
			ISetChangeListener setListener = (ISetChangeListener) listener;
			set.addSetChangeListener(setListener);
		}

		protected void removeCollectionChangeListener(
				IObservableCollection collection, IObservablesListener listener) {
			IObservableSet set = (IObservableSet) collection;
			ISetChangeListener setListener = (ISetChangeListener) listener;
			set.removeSetChangeListener(setListener);
		}
	}

	/**
	 * Constructs an ObservableListTreeContentProvider using the given list
	 * factory.
	 * 
	 * @param setFactory
	 *            observable factory that produces an IObservableSet of children
	 *            for a given parent element. Observable sets created by this
	 *            factory must be on the realm of the current display.
	 * @param structureAdvisor
	 *            an advisor that will be consulted from the implementations of
	 *            the {@link #getParent(Object)} and
	 *            {@link #hasChildren(Object)} methods, or <code>null</code>
	 *            if no advisor is available. It is recommended that clients
	 *            pass a non-null advisor if they can provide additional
	 *            structural information about the tree.
	 */
	public ObservableSetTreeContentProvider(IObservableFactory setFactory,
			TreeStructureAdvisor structureAdvisor) {
		impl = new Impl(setFactory, structureAdvisor);
	}

	public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
		impl.inputChanged(viewer, oldInput, newInput);
	}

	public Object[] getElements(Object inputElement) {
		return impl.getElements(inputElement);
	}

	public boolean hasChildren(Object element) {
		return impl.hasChildren(element);
	}

	public Object[] getChildren(Object parentElement) {
		return impl.getChildren(parentElement);
	}

	public Object getParent(Object element) {
		return impl.getParent(element);
	}

	public void dispose() {
		impl.dispose();
	}

	/**
	 * Returns the set of elements known to this content provider. Label
	 * providers may track this set if they need to be notified about additions
	 * before the viewer sees the added element, and notified about removals
	 * after the element was removed from the viewer. This is intended for use
	 * by label providers, as it will always return the items that need labels.
	 * 
	 * @return readableSet of items that will need labels
	 */
	public IObservableSet getKnownElements() {
		return impl.getKnownElements();
	}
}