package list.dl;

import java.util.NoSuchElementException;
import list.dl.algo.IAlgoLeft;
import list.dl.algo.IAlgoRight;
import list.dl.algo.GetLeftEnd;
import list.dl.algo.GetRightEnd;

/**
 * Node containing data and links to left and right.
 * @author DXN
 * @version 3.2
 * @since 10/17/00
*/
class DataNode extends ANode
{
	   private Object _dat;
	   /** @SBGen Variable (,theLeft,,64)   */
	   private DLList _leftList;
	   /** @SBGen Variable (,theRight,,64)   */
	   private DLList _rightList;

      DataNode (Object dat, DLList leftList, DLList rightList)
      {
         _dat = dat;
         leftList.setRightNode (this);
         rightList.setLeftNode (this);
      }

	   Object getFirst (DLList owner)
      {
         return _dat;
      }

      /**
      * Pre: this node is the left node of owner.
      */
	   DLList getLeftRest (DLList owner)
      {
         return _leftList;
      }

      /**
      * Pre: this node is the right node of owner.
      */
	   DLList getRightRest (DLList owner)
      {
         return _rightList;
      }

	   /**
	   * Sets the left owner link.
	   * @param dllist
	   */
	   void setLeftOwner (DLList dlList)
	   {
         _leftList = dlList;
	   }

	   /**
	   * Sets the right owner link.
	   * @param dllist
	   */
	   void setRightOwner (DLList dlList)
	   {
         _rightList = dlList;
	   }

	   /**
      <Pre>
      Pre: this node is the left node of ownerList.
      Post: this node is the left node of ownerList.getLeftRest ().
      </Pre>
	   * @param dat
	   * @param ownerList
	   */
	   void insertLeftFront (Object dat, DLList ownerList)
      {
         new DataNode (dat, new DLList (this, RightEndNode.Singleton), ownerList);
         /* "Old" style details:
         DLList newList = new DLList ();
         DataNode newNode = new DataNode (dat, newList, ownerList);
         newList.setRightNode (newNode);
         newList.setLeftNode (this);
         _rightList = newList;
         ownerList.setLeftNode (newNode);
         */
      }

	   /**
      <Pre>
      Pre: this node is the right node of ownerList.
      Post: this node is the right node of owner.getRightRest ().
      </Pre>
	   * @param dat
	   * @param ownerList
	   */
	   void insertRightFront (Object dat, DLList ownerList)
      {
         new DataNode (dat, ownerList, new DLList (LeftEndNode.Singleton, this));
      }

      /**
      <Pre>
      Pre: this node is the left node of owner.  X is _leftList.leftNode ().
      Post: owner.leftNode () is X;  _leftList is empty.
      </Pre>
      */
	   Object remLeftFront (DLList owner)
      {
         owner.setLeftNode  (_leftList.getLeftNode());
         _leftList.setRightNode (RightEndNode.Singleton);
         _leftList.setLeftNode (LeftEndNode.Singleton); //_leftList's invariant re-established.
         return _dat;
      }

      /**
      <Pre>
      Pre: this node is the right node of owner.  X is _rightList.rightNode ().
      Post: owner.rightNode () is X;  _rightList is empty.
      </Pre>
      */
	   Object remRightFront (DLList owner)
      {
         owner.setRightNode (_rightList.getRightNode());
         _rightList.setRightNode (RightEndNode.Singleton);
         _rightList.setLeftNode (LeftEndNode.Singleton); //_rightList's invariant re-established.
         return _dat;
      }

	   /**
	   * @param dat
	   */
	   void setFirst (Object dat, DLList owner)
      {
         _dat = dat;
      }

	   /**
      * Pre: this node is the left node of owner.
	   * @param dlList
	   */
      void setLeftRest (DLList dlList, DLList owner)
      {
         _leftList.setRightNode (RightEndNode.Singleton);//_leftList's invariant re-established.
         DLList rightEnd = (DLList)dlList.executeRight (GetRightEnd.Singleton, null);
         rightEnd.setRightNode (this);
      }

	   /**
      * Pre: this node is the right node of owner.
	   * @param dlList
	   */
	   void setRightRest (DLList dlList, DLList owner)
      {
         _rightList.setLeftNode (LeftEndNode.Singleton); //_rightList's invariant re-established.
         DLList leftEnd = (DLList)dlList.executeLeft (GetLeftEnd.Singleton, null);
         leftEnd.setLeftNode (this);
      }

	   /**
       * Pre: this node is the left node of ownerList.
		 * @param algo
		 * @param input
		 * @param owner
		 */
		Object executeLeft (IAlgoLeft algo, Object input, DLList owner)
      {
         return algo.dataNodeCase (owner, input);
      }

   	/**
       * Pre: this node is the right node of ownerList.
		 * @param algo
		 * @param input
		 * @param owner
		 */
		Object executeRight (IAlgoRight algo, Object input, DLList owner)
      {
         return algo.dataNodeCase (owner, input);
      }
}