bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/CheckableCheckedElementsObservableSet.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 124684)
 ******************************************************************************/

package org.eclipse.jface.internal.databinding.viewers;

import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import org.eclipse.core.databinding.observable.Diffs;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.observable.set.AbstractObservableSet;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.viewers.CheckStateChangedEvent;
import org.eclipse.jface.viewers.ICheckStateListener;
import org.eclipse.jface.viewers.ICheckable;

/**
 * 
 * @since 1.2
 */
public class CheckableCheckedElementsObservableSet extends
		AbstractObservableSet {
	private ICheckable checkable;
	private Set wrappedSet;
	private Object elementType;
	private ICheckStateListener listener;

	/**
	 * Constructs a new instance on the given realm and checkable.
	 * 
	 * @param realm
	 *            the observable's realm
	 * @param checkable
	 *            the ICheckable to track
	 * @param elementType
	 *            type of elements in the set
	 */
	public CheckableCheckedElementsObservableSet(Realm realm,
			ICheckable checkable, Object elementType) {
		this(realm, checkable, elementType, new HashSet());
	}

	/**
	 * Constructs a new instance of the given realm, and checkable,
	 * 
	 * @param realm
	 *            the observable's realm
	 * @param checkable
	 *            the ICheckable to track
	 * @param elementType
	 *            type of elements in the set
	 * @param wrappedSet
	 *            the set being wrapped
	 */
	public CheckableCheckedElementsObservableSet(Realm realm,
			ICheckable checkable, Object elementType, final Set wrappedSet) {
		super(realm);
		Assert.isNotNull(checkable, "Checkable cannot be null"); //$NON-NLS-1$
		Assert.isNotNull(wrappedSet, "Wrapped set cannot be null"); //$NON-NLS-1$
		this.checkable = checkable;
		this.wrappedSet = wrappedSet;
		this.elementType = elementType;

		listener = new ICheckStateListener() {
			public void checkStateChanged(CheckStateChangedEvent event) {
				Object element = event.getElement();
				if (event.getChecked()) {
					if (wrappedSet.add(element))
						fireSetChange(Diffs.createSetDiff(Collections
								.singleton(element), Collections.EMPTY_SET));
				} else {
					if (wrappedSet.remove(element))
						fireSetChange(Diffs.createSetDiff(
								Collections.EMPTY_SET, Collections
										.singleton(element)));
				}
			}
		};
		checkable.addCheckStateListener(listener);
	}

	protected Set getWrappedSet() {
		return wrappedSet;
	}

	Set createDiffSet() {
		return new HashSet();
	}

	public Object getElementType() {
		return elementType;
	}

	public boolean add(Object o) {
		getterCalled();
		boolean added = wrappedSet.add(o);
		if (added) {
			checkable.setChecked(o, true);
			fireSetChange(Diffs.createSetDiff(Collections.singleton(o),
					Collections.EMPTY_SET));
		}
		return added;
	}

	public boolean remove(Object o) {
		getterCalled();
		boolean removed = wrappedSet.remove(o);
		if (removed) {
			checkable.setChecked(o, false);
			fireSetChange(Diffs.createSetDiff(Collections.EMPTY_SET,
					Collections.singleton(o)));
		}
		return removed;
	}

	public boolean addAll(Collection c) {
		getterCalled();
		Set additions = createDiffSet();
		for (Iterator iterator = c.iterator(); iterator.hasNext();) {
			Object element = iterator.next();
			if (wrappedSet.add(element)) {
				checkable.setChecked(element, true);
				additions.add(element);
			}
		}
		boolean changed = !additions.isEmpty();
		if (changed)
			fireSetChange(Diffs.createSetDiff(additions, Collections.EMPTY_SET));
		return changed;
	}

	public boolean removeAll(Collection c) {
		getterCalled();
		Set removals = createDiffSet();
		for (Iterator iterator = c.iterator(); iterator.hasNext();) {
			Object element = iterator.next();
			if (wrappedSet.remove(element)) {
				checkable.setChecked(element, false);
				removals.add(element);
			}
		}
		boolean changed = !removals.isEmpty();
		if (changed)
			fireSetChange(Diffs.createSetDiff(Collections.EMPTY_SET, removals));
		return changed;
	}

	public boolean retainAll(Collection c) {
		getterCalled();

		// To ensure that elements are compared correctly, e.g. ViewerElementSet
		Set toRetain = createDiffSet();
		toRetain.addAll(c);

		Set removals = createDiffSet();
		for (Iterator iterator = wrappedSet.iterator(); iterator.hasNext();) {
			Object element = iterator.next();
			if (!toRetain.contains(element)) {
				iterator.remove();
				checkable.setChecked(element, false);
				removals.add(element);
			}
		}
		boolean changed = !removals.isEmpty();
		if (changed)
			fireSetChange(Diffs.createSetDiff(Collections.EMPTY_SET, removals));
		return changed;
	}

	public void clear() {
		removeAll(wrappedSet);
	}

	public Iterator iterator() {
		getterCalled();
		final Iterator wrappedIterator = wrappedSet.iterator();
		return new Iterator() {
			private Object last = null;

			public boolean hasNext() {
				getterCalled();
				return wrappedIterator.hasNext();
			}

			public Object next() {
				getterCalled();
				return last = wrappedIterator.next();
			}

			public void remove() {
				getterCalled();
				wrappedIterator.remove();
				checkable.setChecked(last, false);
				fireSetChange(Diffs.createSetDiff(Collections.EMPTY_SET,
						Collections.singleton(last)));
			}
		};
	}

	public synchronized void dispose() {
		if (checkable != null) {
			checkable.removeCheckStateListener(listener);
			checkable = null;
			listener = null;
		}
		super.dispose();
	}
}