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

/*******************************************************************************
 * Copyright (c) 2007-2008 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.list.IListChangeListener;
import org.eclipse.core.databinding.observable.list.IObservableList;
import org.eclipse.core.databinding.observable.list.ListChangeEvent;
import org.eclipse.core.databinding.observable.list.ListDiffVisitor;
import org.eclipse.core.databinding.observable.masterdetail.IObservableFactory;
import org.eclipse.core.databinding.observable.set.IObservableSet;
import org.eclipse.jface.internal.databinding.viewers.ObservableCollectionTreeContentProvider;
import org.eclipse.jface.internal.databinding.viewers.ViewerElementSet;
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 list factory} to obtain the
 * elements of a tree. Object of this class listen for changes to each
 * {@link IObservableList} 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 ObservableListTreeContentProvider implements ITreeContentProvider {
	private final ObservableCollectionTreeContentProvider impl;

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

		private class ListChangeListener implements IListChangeListener {
			final Object parentElement;

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

			public void handleListChange(ListChangeEvent event) {
				if (isViewerDisposed())
					return;

				final Set removals = ViewerElementSet.withComparer(comparer);
				event.diff.accept(new ListDiffVisitor() {
					public void handleAdd(int index, Object child) {
						// adds to known elements if new element
						getOrCreateNode(child).addParent(parentElement);

						viewerUpdater.insert(parentElement, child, index);
					}

					public void handleRemove(int index, Object child) {
						viewerUpdater.remove(parentElement, child, index);

						removals.add(child);
					}

					public void handleReplace(int index, Object oldChild,
							Object newChild) {
						getOrCreateNode(newChild).addParent(parentElement);

						viewerUpdater.replace(parentElement, oldChild,
								newChild, index);

						removals.add(oldChild);
					}

					public void handleMove(int oldIndex, int newIndex,
							Object child) {
						viewerUpdater.move(parentElement, child, oldIndex,
								newIndex);
					}
				});

				// For each removed element, do not remove node's parent if the
				// element is still present elsewhere in the list.
				removals.removeAll(event.getObservableList());
				for (Iterator iterator = removals.iterator(); iterator
						.hasNext();) {
					TreeNode node = getExistingNode(iterator.next());
					if (node != null)
						// removes from known elements if last parent
						node.removeParent(parentElement);
				}
			}
		}

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

		protected void addCollectionChangeListener(
				IObservableCollection collection, IObservablesListener listener) {
			IObservableList list = (IObservableList) collection;
			IListChangeListener listListener = (IListChangeListener) listener;
			list.addListChangeListener(listListener);
		}

		protected void removeCollectionChangeListener(
				IObservableCollection collection, IObservablesListener listener) {
			IObservableList list = (IObservableList) collection;
			IListChangeListener listListener = (IListChangeListener) listener;
			list.removeListChangeListener(listListener);
		}
	}

	/**
	 * Constructs an ObservableListTreeContentProvider using the given list
	 * factory.
	 * 
	 * @param listFactory
	 *            observable factory that produces an IObservableList of
	 *            children for a given parent element. Observable lists 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 ObservableListTreeContentProvider(IObservableFactory listFactory,
			TreeStructureAdvisor structureAdvisor) {
		impl = new Impl(listFactory, 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();
	}
}