package list.dl;

import list.dl.algo.IAlgoLeft;
import list.dl.algo.IAlgoRight;

   /**
   * Models a node in a doubly-linked list.  Represents the state of the parent list.
   */
abstract class ANode
{
	   abstract Object leftFirst(DLList parent);
   	abstract Object rightFirst(DLList parent);
	   abstract DLList leftRest(DLList parent);
   	abstract DLList rightRest(DLList parent);

      /**
	   * Replaces the first element of the parent left list with the given data element.
	   * @param dat the element that is to replace the first element on the left of the parent list.
      * @param parent the DLList that holds this ANode.
	   */
	   abstract void setLeftFirst(Object dat, DLList parent);

	   /**
	   * Replaces the first element of the parent right list with the given data element.
	   * @param dat the element that is to replace the first element on the left of the parent list.
      * @param parent the DLList that holds this ANode.
	   */
	   abstract void setRightFirst(Object dat, DLList parent);

	   /**
	   * Replaces the left list with the given list.
	   * @param dllist the new tail that is to replace the current one.
      * @param parent the DLList that holds this ANode.
	   */
	   abstract void setLeftRest(DLList dllist, DLList parent);

	   /**
	   * Replaces the right list with the given list.
	   * @param dllist the new tail that is to replace the current one.
      * @param parent the DLList that holds this ANode.
	   */
	   abstract void setRightRest(DLList dllist, DLList parent);

      /**
      * Sets the left parent link.
      */
      abstract void setLeftParent (DLList dllist);

      /**
      * Sets the right parent link.
      */
      abstract void setRightParent (DLList dllist);

	   /**
	   * Inserts a data element to the left front of the parent list.
	   * @param dat the element to be inserted to the left front of the parent.
      * @param parent the DLList that holds this ANode.
	   */
	   abstract void insertLeftFront(Object dat, DLList parent);

	   /**
	   * Inserts a data element to the right front of the parent list.
	   * @param dat the element to be inserted to the right front of the parent.
      * @param parent the DLList that holds this ANode.
	   */
	   abstract void insertRightFront(Object dat, DLList parent);


	   /**
	   * Removes and returns the first element on the left of the parent DLList.
      * @param parent the DLList that holds this ANode.
	   */
	   abstract Object remLeftFirst(DLList parent);

	   /**
	   * Removes and returns the first element on the right of the parent DLList.
      * @param parent the DLList that holds this ANode.
	   */
	   abstract Object remRightFirst(DLList parent);

	   /**
	   * @param algo
	   * @param input
	   * @param parentList
	   */
	   abstract Object executeLeft(IAlgoLeft algo, Object input, DLList ownerList);

	   /**
	   * @param algo
	   * @param inputParam
	   * @param parentList
	   */
	   abstract Object executeRight(IAlgoRight algo, Object input, DLList parentList);
}