package binaryTree;

/**
 * Represents the state of the parent binary tree structure.  Union pattern
 * @author Dung X. Nguyen - Copyright 1999 - All rights reserved.
 */
abstract class ANode
{
	/**
    * Gets the root data of the parent tree if it exists.
	 * @param parent the context of the state.
	 * @return the data element of this node if it exists.
    * @exception NoSuchElementException if the parent is empty.
	 */
	abstract Object getRootDat(BiTree parent);

	/**
    * Sets the root element of the parent tree to a given data object.
	 * @param dat
	 * @param parent the context of this state.
    * @exception NoSuchElementException if the parent is empty.
	 */
	abstract void setRootDat(Object dat, BiTree parent);

	/**
    * Gets the left subtree of the parent tree.
	 * @param parent the context of this state.
	 * @return the left subtree of this node if it exists.
    * @exception NoSuchElementException if the parent is empty.
	 */
	abstract BiTree getLeftSubTree(BiTree parent);

	/**
    * Gets the right subtree of the parent tree.
	 * @param parent the context of this state.
	 * @return the right subtree of this node if it exists.
    * @exception NoSuchElementException if the parent is empty.
	 */
	abstract BiTree getRightSubTree(BiTree parent);

	/**
    * Sets the left subtree of the parent tree to a given tree.
    * Allows for growing the parent tree.
	 * @param biTree != null.
	 * @param parent the context of this state.
    * @exception NoSuchElementException if the parent is empty.
	 */
	abstract void setLeftSubTree(BiTree biTree, BiTree parent);

	/**
    * Sets the right subtree of the parent tree to a given tree.  Allows for growing
    * the parent tree.
	 * @param biTree != null.
	 * @param parent the context of this state.
    * @exception NoSuchElementException if the parent is empty.
	 */
	abstract void setRightSubTree(BiTree biTree, BiTree parent);

	/**
    * Inserts a root element to the parent tree.
    * Allows for state change from empty to non-empty.
	 * @param dat
	 * @param parent the context of this state.
    * @exception IllegaStateException if the parent is not empty.
	 */
	abstract void insertRoot(Object dat, BiTree parent);

	/**
    * Removes and returns the root element from the parent tree.
    * Allows for state change from non-empty to empty.
	 * @param dat
	 * @param parent the context of this state.
    * @exception IllegaStateException if the parent has more than one element.
	 */
	abstract Object remRoot(BiTree parent);

	/**
    * Removes and return the root element of the grandparent of this node,
    * asking the sibbling of the parent tree to do it if necessary.
	 * @param aunt the sibbling of the parent of this node.
	 * @param grandPo the grand parent of this node.
	 * @param mom the parent (i.e. context) of this node.
    * @return the root data of the grandparent of this node.
	 */
	abstract Object remParent(BiTree aunt, BiTree grandPo, BiTree mom);

	/**
    * Removes and return the root element of the grandparent of this node,
    * <I>knowing</I> that the sibbling of the parent tree is empty.
	 * @param grandParent the grand parent of this BiTree.
    * @param parent the context of this node.
    * @return the root data of the grandparent of this node.
	 */
	abstract Object remOurParent(BiTree grandParent, BiTree parent);

	/**
    * Calls the appropriate visitor's method to execute the visiting algorithm.
	 * @param algo the visiting algorithm
	 * @param input the input the algorithm needs.
	 * @param parent the context of this node.
	 * @return the output for the algorithm.
	 */
	abstract Object execute(IVisitor algo, Object input, BiTree parent);
}