public class Heap<NODE> implements IHeap<NODE> {
	
	/**
	 * First element is always null, nodes are stored beginning with index [1].
	 */
	private NODE[] nodes;
	private int count;
	private int items;
	private HashMap<NODE, Integer> references;
	private Comparator<NODE> cmp;
	
	private void grow(){
		NODE[] tempNodes = (NODE[]) new Object[count*2];
		for (int i = 0; i <= items; ++i){
			tempNodes[i] = nodes[i];
		}
		nodes = tempNodes;
		count = count * 2;
	}
	
	private int left(int reference){
		return 2*reference;
	}
	
	private int right(int reference){
		return 2*reference+1;
	}
	
	private int upRef(int reference){
		return reference / 2;
	}
	
	private NODE getNode(int reference){
		while (reference >= count) 
			grow();		
		return nodes[reference];
	}
	
	private int downNode(int reference){
		NODE currentNode = getNode(reference);
		if (currentNode == null) {
			return reference;
		}
		NODE leftNode = null;
		NODE rightNode = null;
		int way = 0;
	
		while (true){
			way = 0;
			leftNode = getNode(left(reference));
			rightNode = getNode(right(reference));
		
			if ((leftNode == null) && (rightNode == null)){
				references.put(currentNode, reference);
				return reference;
			}
			if (rightNode == null) way = -1;
			else
				if (leftNode  == null) way = 1;
			if (way == 0) way = cmp.compare(leftNode, rightNode);
			
			if (way < 0){
				// we've got to ascend to the left
				if (cmp.compare(currentNode, leftNode) > 0){
					nodes[reference] = leftNode;
					references.put(leftNode, new Integer(reference));
					reference = left(reference);
					nodes[reference] = currentNode;					
				} else {
					references.put(currentNode, reference);				
					return reference;
				}				 
			} else {
				// we've got to ascend to the right
				if (cmp.compare(currentNode, rightNode) > 0){
					nodes[reference] = rightNode;
					references.put(rightNode, new Integer(reference));
					reference = right(reference);
					nodes[reference] = currentNode;					
					
				} else {
					references.put(currentNode, reference);				
					return reference;
				}				 
			}			
		}		
	}
	
	private int upNode(int reference){
		if (reference == 1) 
			return reference;
		NODE currentNode = getNode(reference);
		if (currentNode == null) 
			return reference;
		NODE upNode = null;
		while (reference > 1){
			upNode = getNode(upRef(reference));
			if (cmp.compare(currentNode, upNode) < 0){
				nodes[reference] = upNode;
				references.put(upNode, reference);				
				reference = upRef(reference);
			} else {
				break;
			}
		}
		nodes[reference] = currentNode;
		references.put(currentNode, reference);
		return reference;
	}
	
	private void initHeap(int capacity){
		if (capacity < 2) capacity = 2;
		nodes = (NODE[]) new Object[capacity];
		count = capacity;
		items = 0;
		references = new HashMap(capacity);
	}
	
	public Heap(Comparator<NODE> comp, int capacity){

	public WeakHashTriMap( int primaryCapacity, int secondaryCapacity, int tertiaryCapacity)
	{
		super(primaryCapacity);
		this.secondaryCapacity = secondaryCapacity;
		this.tertiaryCapacity = tertiaryCapacity;
	}
	
	/**
	 * Returns a HashMap<SECONDARY_KEY,HashMap<TERTIARY_KEY,ITEM>>
	 * Never returns null, if the map under primary key doesn't exist, an empty one is added and returned.
	 * @param primaryKey
	 * @return
	 */
	@SuppressWarnings("unchecked")
	@Override
	public Map<SECONDARY_KEY, Map<TERTIARY_KEY,ITEM>> get(Object primaryKey)
	{
		Map<SECONDARY_KEY, Map<TERTIARY_KEY,ITEM>> result = super.get(primaryKey);
		if (result != null) { return result; };
		result = Collections.synchronizedMap( new HashMapMap<SECONDARY_KEY,TERTIARY_KEY,ITEM>(secondaryCapacity, tertiaryCapacity) );
		super.put( (PRIMARY_KEY)primaryKey,result);
		return result;
	}
	
	/**
	 * Returns the requested map, never returns null.
	 * If the map does not exist an empty map is created and returned.
	 * @param primaryKey
	 * @param secondaryKey
	 * @return
	 */
	public Map<TERTIARY_KEY,ITEM> get(PRIMARY_KEY primaryKey, SECONDARY_KEY secondaryKey)
	{
		Map<TERTIARY_KEY, ITEM> result = get(primaryKey).get(secondaryKey);
		if (result != null) { return result; };
		result = Collections.synchronizedMap( new HashMap<TERTIARY_KEY,ITEM>( tertiaryCapacity ));
		get(primaryKey).put(secondaryKey, result);
		return result;
	}
	
	/**
	 * Returns item specified, returns null if item does not appear in the map.
	 * @param primaryKey
	 * @param secondaryKey
	 * @param tertiaryKey
	 * @return
	 */
	public ITEM get(PRIMARY_KEY primaryKey, SECONDARY_KEY secondaryKey, TERTIARY_KEY tertiaryKey)
	{
		return get(primaryKey,secondaryKey).get(tertiaryKey);
	}
	
	/**
	 * Puts the item into the map.
	 * @param primaryKey
	 * @param secondaryKey
	 * @param tertiaryKey
	 * @param item
	 */
	public void put(PRIMARY_KEY primaryKey, SECONDARY_KEY secondaryKey, TERTIARY_KEY tertiaryKey, ITEM item)
	{
		get(primaryKey,secondaryKey).put(tertiaryKey, item);
	}
	
	/**
	 * Removes the requested map. If the map doesn't exist, returns an empty map.
	 */
	@Override
	public Map<SECONDARY_KEY, Map<TERTIARY_KEY,ITEM>> remove(Object primaryKey)
	{
		Map<SECONDARY_KEY, Map<TERTIARY_KEY,ITEM>> result = super.remove(primaryKey);
		if (result != null) { return result; };
		return Collections.synchronizedMap( new HashMapMap<SECONDARY_KEY, TERTIARY_KEY,ITEM>(secondaryCapacity, tertiaryCapacity) );
	}
	
	/**
	 * removes the map under primary and secondary key, if the map does not exist,
	 * the data structure is not changed and a new map is returned.
	 * @param primaryKey
	 * @param secondaryKey
	 * @return
	 */
	public Map<TERTIARY_KEY,ITEM> remove(PRIMARY_KEY primaryKey, SECONDARY_KEY secondaryKey)
	{
		Map<TERTIARY_KEY,ITEM> result = get(primaryKey).remove(secondaryKey);
		if ( result != null) { return result; };
		return Collections.synchronizedMap( new HashMap<TERTIARY_KEY, ITEM> (tertiaryCapacity));
	}
	
	/**
	 * Returns the item under specified keys and removes it from the map,
	 * returns null if item is not present in the map.
	 * @param primaryKey
	 * @param secondaryKey
	 * @param tertiaryKey
	 * @return
	 */
	public ITEM remove(PRIMARY_KEY primaryKey, SECONDARY_KEY secondaryKey, TERTIARY_KEY tertiaryKey)
	{
		return get(primaryKey,secondaryKey).remove(tertiaryKey);
	}

}

    public int removeListener(EventListener listener) {
    	if (listener == null) return 0;
    	int removed = 0;
    	synchronized(listeners) {
    		boolean listenersIterationOriginal = listenersIteration;
    		listenersIteration = true;
    		
    		try {
	    		Iterator<ListenerStore<Listener>> iterator = listeners.iterator();
	    		while(iterator.hasNext()) {
	    			ListenerStore<Listener> store = iterator.next(); 
	    			Listener storedListener = store.getListener();
	    			if (storedListener == null) {
	    				if (!listenersIterationOriginal) {
	    					if ((store instanceof WeakListenerStore) && log != null && log.isLoggable(Level.FINE)) {
	    						log.fine((name == null ? "" : name + ": ") + "Weakly referenced listener was GC()ed.");
	    					}
	    					iterator.remove();
	    				}
	    				continue;
	    			}
	    			if (listener == storedListener) {

    public boolean isListening(EventListener listener) {
    	if (listener == null) return false;
    	synchronized(listeners) {
    		boolean listenersIterationOriginal = listenersIteration;
    		listenersIteration = true;
    		
    		try {
	    		Iterator<ListenerStore<Listener>> iterator = listeners.iterator();
	    		while(iterator.hasNext()) {
	    			ListenerStore<Listener> store = iterator.next();
	    			Listener storedListener = store.getListener();
	    			if (storedListener == null) {
	    				if (!listenersIterationOriginal) {
	    					if ((store instanceof WeakListenerStore) && log != null && log.isLoggable(Level.FINE)) {
	    						log.fine((name == null ? "" : name + ": ") + "Weakly referenced listener was GC()ed.");
	    					}
	    					iterator.remove();
	    				}
	    				continue;
	    			}
	    			if (listener == storedListener) {

	public boolean add(NODE arg0) {
		Integer reference = (Integer)references.get(arg0);
		if (reference == null){
			getNode(items+1); // ensure that capacity is sufficient
			nodes[items+1] = arg0;
			upNode(items+1);
			items = items + 1;
			return true;
		} else {
			int tempRef = upNode(reference.intValue());
			if (tempRef == reference.intValue()) 
				downNode(reference.intValue());
			return true;
		}		
	}

	@Override
	public boolean addAll(Collection arg0) {
		Iterator<NODE> iter = arg0.iterator();
		while (iter.hasNext())
			add(iter.next());		
		return true;
	}

    	synchronized(listeners) {
    		boolean listenersIterationOriginal = listenersIteration;
    		listenersIteration = true;
    		
    		try {
	    		Iterator<ListenerStore<Listener>> iterator = listeners.iterator();
	    		while(iterator.hasNext()) {
	    			ListenerStore<Listener> store = iterator.next();
	    			Listener storedListener = store.getListener();
	    			if (storedListener == null) {
	    				if (!listenersIterationOriginal) {
	    					if ((store instanceof WeakListenerStore) && log != null && log.isLoggable(Level.FINE)) {
	    						log.fine((name == null ? "" : name + ": ") + "Weakly referenced listener was GC()ed.");
	    					}
	    					iterator.remove();
	    				}
	    				continue;
	    			}
	    			if (listener.equals(storedListener)) {

    	synchronized(listeners) {
    		boolean listenersIterationOriginal = listenersIteration;
    		listenersIteration = true;
    		
    		try {
	    		Iterator<ListenerStore<Listener>> iterator = listeners.iterator();
	    		while(iterator.hasNext()) {
	    			ListenerStore<Listener> store = iterator.next();
	    			Listener storedListener = store.getListener();
	    			if (storedListener == null) {
	    				if (!listenersIterationOriginal) {
	    					if ((store instanceof WeakListenerStore) && log != null && log.isLoggable(Level.FINE)) {
	    						log.fine((name == null ? "" : name + ": ") + "Weakly referenced listener was GC()ed.");
	    					}
	    					iterator.remove();
	    				}
	    				continue;
	    			}
	    			if (listener == storedListener) {

    	synchronized(listeners) {
    		boolean listenersIterationOriginal = listenersIteration;
    		listenersIteration = true;
    		
    		try {
	    		Iterator<ListenerStore<Listener>> iterator = listeners.iterator();
	    		while(iterator.hasNext()) {
	    			ListenerStore<Listener> store = iterator.next();
	    			Listener storedListener = store.getListener();
	    			if (storedListener == null) {
	    				if (!listenersIterationOriginal) {
	    					if ((store instanceof WeakListenerStore) && log != null && log.isLoggable(Level.FINE)) {
	    						log.fine((name == null ? "" : name + ": ") + "Weakly referenced listener was GC()ed.");
	    					}
	    					iterator.remove();
	    				}
	    				continue;
	    			}
	    			if (listener == storedListener) {

    	synchronized(listeners) {
    		boolean listenersIterationOriginal = listenersIteration;
    		listenersIteration = true;
    		try {
	    		Iterator<ListenerStore<Listener>> iterator = listeners.iterator();
	    		while(iterator.hasNext()) {
	    			ListenerStore<Listener> store = iterator.next();
	    			Listener storedListener = store.getListener();
	    			if (storedListener == null) {
	    				if (!listenersIterationOriginal) {
	    					if ((store instanceof WeakListenerStore) && log != null && log.isLoggable(Level.FINE)) {
	    						log.fine((name == null ? "" : name + ": ") + "Weakly referenced listener was GC()ed.");
	    					}
	    					iterator.remove();
	    				}
	    				continue;
	    			}
	    			if (remover.remove(storedListener)) {

    	synchronized(listeners) {
    		boolean listenersIterationOriginal = listenersIteration;
    		listenersIteration = true;
    		try {
	    		Iterator<ListenerStore<Listener>> iterator = listeners.iterator();
	    		while(iterator.hasNext()) {
	    			ListenerStore<Listener> store = iterator.next();
	    			Listener storedListener = store.getListener();
	    			if (storedListener == null) {
	    				if (!listenersIterationOriginal) {
	    					if ((store instanceof WeakListenerStore) && log != null && log.isLoggable(Level.FINE)) {
	    						log.fine((name == null ? "" : name + ": ") + "Weakly referenced listener was GC()ed.");
	    					}
	    					iterator.remove();
	    				}
	    				continue;
	    			}

		});
		super.put((PRIMARY_KEY)primaryKey, map);
		return map;
	}
	
	/**
	 * Returns an item under primary and secondary key if exists (otherwise a null is returned).
	 * @param primaryKey
	 * @param secondaryKey
	 * @return
	 */
	public ITEM get(PRIMARY_KEY primaryKey, SECONDARY_KEY secondaryKey) {
		return get(primaryKey).get(secondaryKey);
	}
	
	/**
	 * Inserts an item under primary and then secondary key.
	 * @param primaryKey
	 * @param secondaryKey
	 * @param item
	 */
	public void put(PRIMARY_KEY primaryKey, SECONDARY_KEY secondaryKey, ITEM item) {
		get(primaryKey).put(secondaryKey, item);
	}
	
	/**
	 * Remove returns the removed item, if item was non-existent, it returns empty map. 
	 * @param primaryKey
	 * @return
	 */
	@Override
	public Map<SECONDARY_KEY, ITEM> remove(Object primaryKey) {
		Map<SECONDARY_KEY, ITEM> map = super.remove(primaryKey);
		if (map != null) return map;
		return Collections.synchronizedMap(new LazyMap<SECONDARY_KEY, ITEM>(){