package clist;

/**
* Circular doubly-linked list implemented via the state pattern.
* Framework with hooks to execute algorithms as visitors.
* The notion of setting the "tail" of circular list does not make sense.  Thus
* CLList has no setTail method.
* @author D. X. Nguyen
* @since 10/24/00
*/
public class CLList
{
	/** @SBGen Variable (,,,64)   */
	private ANode _clockwiseHead;
	/** @SBGen Variable (,,,64)   */
	private ANode _counterwiseHead;

	public CLList()
	{
      _clockwiseHead = EmptyNode.Singleton;
      _counterwiseHead = EmptyNode.Singleton;
	}

	final public Object getClockwiseDat()
	{
      return _clockwiseHead.getDat (this);
	}

	final public Object getCounterwiseDat()
	{
      return _counterwiseHead.getDat (this);
	}

	final public CLList setClockwiseDat (Object dat)
	{
      return _clockwiseHead.setDat (dat, this);
	}

	final public CLList setCounterwiseDat (Object dat)
	{
      return _counterwiseHead.setDat (dat, this);
	}

	/**
	 * @param dat
	 */
   final public CLList insertClockwise(Object dat)
	{
      return _clockwiseHead.insertClockwise (dat, this);
	}

	final public CLList insertCounterwise(Object dat)
	{
      return _counterwiseHead.insertCounterwise (dat, this);
	}

	final public Object remClockwise()
	{
      return _clockwiseHead.remClockwise (this);
	}

	final public Object remCounterwise()
	{
      return _counterwiseHead.remCounterwise (this);
	}

	final public CLList getClockwiseTail()
	{
      return _clockwiseHead.getClockwiseTail (this);
	}

	final public CLList getCounterwiseTail()
	{
      return _counterwiseHead.getCounterwiseTail (this);
	}

	final public Object execClockwise (ICLVisitor algo, CLList start, Object input)
	{
     return _clockwiseHead.execute (algo, start, input, this);
	}

	final public Object execCounterwise (ICLVisitor algo, CLList start, Object input)
	{
     return _counterwiseHead.execute (algo, start, input, this);
	}
   
	/**
   * When this CLList is brought into existence, all the wiring have been done right!
   * This is of vital importance!
	 * @param clockwiseHead
	 * @param counterwiseHead
	 */
	CLList(ANode counterwiseHead, ANode clockwiseHead)
	{
		_clockwiseHead = clockwiseHead;
      _clockwiseHead.setCounterwiseOwner (this);
      _counterwiseHead = counterwiseHead;
      _counterwiseHead.setClockwiseOwner (this);
	}

	/**
   * Makes node the clockwise node of owner and owner the counterClockwise owner of node.
   * Proper wiring is of vital importance.  And it is done here in one place.
	 * @param node
	 */
	final void setClockwiseHead(ANode node)
	{
		_clockwiseHead = node;
      _clockwiseHead.setCounterwiseOwner (this);
	}

	/**
   * Makes node the counter-clockwise node of owner and owner the clockwise owner of node.
   * Proper wiring is of vital importance.  And it is done here in one place.
	 * @param node
	 */
	final void setCounterwiseHead(ANode node)
	{
      _counterwiseHead = node;
      _counterwiseHead.setClockwiseOwner (this);
	}

	final ANode getClockwiseHead()
	{
      return _clockwiseHead;
	}

	final ANode getCounterwiseHead()
	{
      return _counterwiseHead;
	}
}