package clist;

class EmptyNode extends ANode
{
	public final static EmptyNode Singleton = new EmptyNode ();

	private EmptyNode ()
	{
	}

	/**
	 * @param owner 
	 * @return 
	 */
	Object getDat (CLList owner)
	{
		throw new java.util.NoSuchElementException ("Null Node has no data");
	}

	/**
	 * @param owner 
	 * @return 
	 */
	CLList setDat (Object dat, CLList owner)
	{
		throw new IllegalArgumentException ("Null Node has no data");
	}

	/**
	 * @param dat 
	 * @param owner 
	 */
	CLList insertClockwise(Object dat, CLList owner)
	{
      new DatNode (dat, owner, owner);
      return owner;
	}

	/**
	 * @param dat 
	 * @param owner 
	 */
	CLList insertCounterwise(Object dat, CLList owner)
	{
      new DatNode (dat, owner, owner);
      return owner;
	}

	/**
	 * @param owner 
	 * @return 
	 */
	Object remClockwise(CLList owner)
	{
		throw new java.util.NoSuchElementException ("Null Node has no data");
	}

	/**
	 * @param owner 
	 * @return 
	 */
	Object remCounterwise(CLList owner)
	{
		throw new java.util.NoSuchElementException ("Null Node has no data");
	}

	/**
	 * @param owner 
	 * @return 
	 */
	CLList getClockwiseTail (CLList owner)
	{
		throw new java.util.NoSuchElementException ("Null Node has no clockwise tail");
	}

	/**
	 * @param owner 
	 * @return 
	 */
	CLList getCounterwiseTail(CLList owner)
	{
		throw new java.util.NoSuchElementException ("Null Node has no counter clockwise tail.");
	}

	/**
	 * @param algo 
	 * @param stop 
	 * @param input 
	 * @param owner 
	 * @return 
	 */
	Object execute(ICLVisitor algo, CLList stop, Object input, CLList owner)
	{
		return algo.forEmpty (owner, stop, input);
	}

	/**
	 * @param cllist 
	 */
	void setClockwiseOwner(CLList cllist)
	{
      // do nothing.
	}

	/**
	 * @param cllist 
	 */
	void setCounterwiseOwner(CLList cllist)
	{
      // do nothing.
	}
}