package clist;

class DatNode extends ANode
{
  private Object _dat;
  private CLList _clockwiseTail;
  private CLList _counterwiseTail;

  DatNode(Object dat, CLList counterwiseParent, CLList clockwiseParent)
  {
    _dat = dat;

    clockwiseParent.setCounterwiseHead(this);
    counterwiseParent.setClockwiseHead(this);
  }

  Object getDat(CLList parent)
  {
    return _dat;
  }

  void setDat(Object dat, CLList parent)
  {
    _dat = dat;
  }

  CLList getClockwiseTail(CLList parent)
  {
    return _clockwiseTail;
  }

  void setClockwiseParent(CLList cllist)
  {
    _clockwiseTail = cllist;
  }

  CLList getCounterwiseTail(CLList parent)
  {
    return _counterwiseTail;
  }

  void setCounterwiseParent(CLList cllist)
  {
    _counterwiseTail = cllist;
  }

  void insertClockwise(Object dat, CLList parent)
  {
    new DatNode(dat, parent, new CLList(NullNode.Singleton, this));
  }

  void insertCounterwise(Object dat, CLList parent)
  {
    new DatNode(dat, new CLList(this, NullNode.Singleton), parent);
  }

  Object removeClockwise(CLList parent)
  {
    if (parent.equals(_clockwiseTail))
      {
	parent.setClockwiseHead(NullNode.Singleton);
	parent.setCounterwiseHead(NullNode.Singleton);
      }
    else
      {
	parent.setClockwiseHead(_clockwiseTail.getClockwiseHead());

	_clockwiseTail.setClockwiseHead(NullNode.Singleton);
	_clockwiseTail.setCounterwiseHead(NullNode.Singleton);
      }
    return _dat;
  }

  Object removeCounterwise(CLList parent)
  {
    if (parent.equals(_counterwiseTail))
      {
	parent.setClockwiseHead(NullNode.Singleton);
	parent.setCounterwiseHead(NullNode.Singleton);
      }
    else
      {
	parent.setCounterwiseHead(_counterwiseTail.getCounterwiseHead());

	_counterwiseTail.setClockwiseHead(NullNode.Singleton);
	_counterwiseTail.setCounterwiseHead(NullNode.Singleton);
      }
    return _dat;
  }

  Object execClockwise(ICLVisitor algo, CLList start, Object input, CLList parent)
  {
    return algo.nonNullCase(parent, start, input);
  }

  Object execCounterwise(ICLVisitor algo, CLList start, Object input, CLList parent)
  {
    return algo.nonNullCase(parent, start, input);
  }
}