package binaryTree;

/**
* Stores data and represents a non-empty state.
* @author Dung X. Nguyen - Copyright 1999 - All rights reserved.
* @since 11/10/99
*/
class DatNode extends ANode
{
	/**
	 * Data Invariant: != null.
	 * @SBGen Variable (,left subtree,,64)
	 */
	private BiTree _leftTree = new BiTree ();
	/**
	 * the stored data element.
	 */
	private Object _dat;
	/**
	 * Data Invariant: != null.
	 * @SBGen Variable (,right subtree,,64)
	 */
	private BiTree _rightTree = new BiTree ();

	/**
    * Initialize the data element to a given object.
	 * @param dat
	 */
	DatNode(Object dat)
	{
		_dat = dat;
	}


	/**
    * Gets the root data of the parent Tree.
	 * @param parent the context of the state.
	 * @return the data element of this node.
	 */
	Object getRootDat(BiTree parent)
	{
		return _dat;
	}

	/**
    * Sets the data element of this node to a given data object.
	 * @param dat 
	 * @param parent the context of this state.
	 */
	void setRootDat(Object dat, BiTree parent)
	{
      _dat = dat;
	}

	/**
    * Gets the left subtree of the parent tree.
	 * @param parent the context of this state.
	 * @return the left subtree of this node.
	 */
	BiTree getLeftSubTree(BiTree parent)
	{
		return _leftTree;
	}

	/**
    * Gets the right subtree of the parent tree.
	 * @param parent the context of this state.
	 * @return the right subtree of this node.
	 */
	BiTree getRightSubTree(BiTree parent)
	{
		return _rightTree;
	}

	/**
    * Sets the left subtree of this node to a given tree.
    * Allows for growing the parent tree.
	 * @param biTree != null.
	 * @param parent the context of this state.
	 */
	void setLeftSubTree(BiTree biTree, BiTree parent)
	{
      _leftTree = biTree;
	}

	/**
    * Sets the right subtree of this node to a given tree.
    * Allows for growing the parent tree.
	 * @param biTree != null.
	 * @param parent the context of this state.
	 */
	void setRightSubTree(BiTree biTree, BiTree parent)
	{
      _rightTree = biTree;
	}

	/**
    * Throws an IllegalStateException because the parent tree is not empty.
    * @exception IllegaStateException.
	 */
	void insertRoot(Object dat, BiTree parent)
	{
		throw new IllegalStateException ("DatNode.insertRoot - Tree is not empty.");
	}

	/**
    * Removes and returns the root element from the parent tree by handing the right
    * subtree to the left subtree to do the job.
	 * @param dat
	 * @param parent the context of this state.
    * @exception IllegaStateException if the parent has more than one element.
	 */
	Object remRoot(BiTree parent)
	{
		return _leftTree.remParent (_rightTree, parent);
	}

	/**
    * Throws an IllegalStateException because the parent tree is not empty.
	 */
	Object remParent(BiTree sis, BiTree grandPo, BiTree mom)
	{
		throw new IllegalStateException ("Tree has more than one element.");
	}

	/**
    * Throws an IllegalStateException because the parent tree is not empty.
	 */
	Object remOurParent(BiTree grandParent, BiTree parent)
	{
		throw new IllegalStateException ("Tree has more than one element.");
	}
   
	/**
    * Calls the visitor's nonNullCase () 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 nonNullCase() of the algorithm.
	 */
	Object execute(IVisitor algo, Object input, BiTree parent)
	{
		return algo.nonEmptyCase (parent, input);
	}
}