org.eclipse.viatra2.core2/src/org/eclipse/viatra2/core/simple/SmallTreeSet2.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 <T>
 *
 */
public class SmallTreeSet2<T> implements Set<T> {
	TreeSet<T> set = null;

	T o = null;

	public int size() {
		if (set == null) {
			return o == null ? 0 : 1;
		} else
			return set.size();
	}

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

	}

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

	/*
	 * class OneIterator<E> implements Iterator { E o; OneIterator(E o) {
	 * this.o=o; } public boolean hasNext() { return o!=null;} public E next() {
	 * E ret=o; o=null; return ret;} public void remove() {} }
	 */
	public Iterator<T> iterator() {
		if (set == null) {
			return new OneIterator<T>(o);
		} else
			return set.iterator();
	}

	public Object[] toArray() {
		if (set == null) {
			if (o == null) {
				return new Object[0];
			} else {
				Object[] ret = new Object[1];
				ret[0] = o;
				return ret;
			}
		} else
			return set.toArray();
	}

	public <K> K[] toArray(K[] arg0) {
		/*
		 * if(set==null) { if(o!=null) { Object x=o; arg0[0]=(K)x; } return
		 * arg0; } else return set.toArray(arg0);
		 */
		return null;
	}

	public boolean add(T arg0) {
		if (set == null) {
			if (o == null) {
				o = arg0;
				return true;
			} else {
				if (o.equals(arg0)) {
					return false;
				} else {
					set = new TreeSet<T>();
					set.add(o);
					o = null;
					return set.add(arg0);
				}
			}
		} else
			return set.add(arg0);
	}

	public boolean remove(Object arg0) {
		if (set == null) {
			if (o != null && o.equals(arg0)) {
				o = null;
				return true;
			} else
				return false;
		} else {
			boolean ret = set.remove(arg0);
			if (set.size() == 0) {
				set = null;
			} else if (set.size() == 1) {
				o = set.iterator().next();
				set = null;
			}
			return ret;
		}
	}

	public boolean containsAll(Collection arg0) {
		if (set == null) {
			if (o != null) {
				if (arg0.size() == 1) {
					return arg0.iterator().next().equals(o);
				} else
					return false;
			} else {
				return arg0.size() == 0;
			}
		} else {
			return set.containsAll(arg0);
		}
	}

	public boolean addAll(Collection<? extends T> arg0) {
		if (set == null) {
			if (arg0.size() > 1) {
				set = new TreeSet<T>();
				return set.addAll(arg0);
			} else if (arg0.size() == 1) {
				o = arg0.iterator().next();
				return true;
			} else
				return false;
		} else {
			return set.addAll(arg0);
		}
	}

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

	public boolean removeAll(Collection arg0) {
		throw new UnsupportedOperationException();
		/*
		 * 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) {
			o = null;
			return;
		} else
			set.clear();
	}

	public boolean equals(Object o) {
		if (o == null) {
			return set == null;
		} if (o instanceof Set<?>) {
			Set<?> ob = (Set<?>) o;
			if (set == null) {
				return ob.size() == 0;
			} else if (set == null) {
				if (ob.size() == 1)
					return ob.iterator().next().equals(o);
				else
					return false;
			} else
				return set.equals(ob);
		} else {
			return false;
		}
	}

}