plugins/org.eclipse.viatra2.core2/src/org/eclipse/viatra2/core/simple/SmallTreeSet.java

/*******************************************************************************
 * Copyright (c) 2004-2008 Andras Schmidt, Andras Balogh, Istvan Rath and Daniel Varro
 * 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:
 *    Andras Schmidt, Andras Balogh, Istvan Rath - initial API and implementation
 *******************************************************************************/

package org.eclipse.viatra2.core.simple;

import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import java.util.TreeSet;

/**
 * @author Andras Schmidt
 * @param <E>
 *
 */
public class SmallTreeSet<E> implements Set<E> {
	TreeSet<E> set = null;

	public int size() {
		if (set == null) {
			return 0;
		} else
			return set.size();
	}

	public boolean isEmpty() {
		if (set == null)
			return true;
		else
			return set.isEmpty();

	}

	public boolean contains(Object arg0) {
		if (set == null)
			return false;
		else
			return set.contains(arg0);
	}

	class NullIterator<F> implements Iterator<F> {
		public boolean hasNext() {
			return false;
		}

		public F next() {
			return null;
		}

		public void remove() {
		}
	}

	public Iterator<E> iterator() {
		if (set == null)
			return new NullIterator<E>();
		else
			return set.iterator();
	}

	public Object[] toArray() {
		if (set == null)
			return new Object[0];
		else
			return set.toArray();
	}

	public <T> T[] toArray(T[] arg0) {
		if (set == null)
			return arg0;
		else
			return set.toArray(arg0);
	}

	public boolean add(E arg0) {
		if (set == null) {
			set = new TreeSet<E>();
			return set.add(arg0);
		} else
			return set.add(arg0);
	}

	public boolean remove(Object arg0) {
		if (set == null)
			return false;
		else {
			boolean ret = set.remove(arg0);
			if (set.size() == 0)
				set = null;
			return ret;
		}
	}

	public boolean containsAll(Collection arg0) {
		if (set == null) {
			return arg0.size() == 0;
		} else {
			return set.containsAll(arg0);
		}
	}

	public boolean addAll(Collection<? extends E> arg0) {
		if (set == null) {
			if (arg0.size() != 0) {
				set = new TreeSet<E>();
				return set.addAll(arg0);
			} else
				return false;
		} else {
			return set.addAll(arg0);
		}
	}

	public boolean retainAll(Collection arg0) {
		throw new UnsupportedOperationException();
	}

	public boolean removeAll(Collection arg0) {
		if (set == null) {
			return false;
		} else {
			boolean ret = set.removeAll(arg0);
			if (set.size() == 0)
				set = null;
			return ret;
		}
	}

	public void clear() {
		if (set == null)
			return;
		else
			set.clear();
	}

	public boolean equals(Object o) {
		if (o instanceof Set) {
			Set ob = (Set) o;
			if (set == null) {
				return ob.size() == 0;
			} else
				return set.equals(ob);
		} else {
			return false;
		}
	}
}