package binaryTree.visitor;

import binaryTree.*;

/**
 * Prints the binary tree host vertically.
 * @author Alan L. Cox
 * @author Dung X. Nguyen
 * @since 04/05/01
 */
public class VerticalPrintHelper implements IAlgo
{
    public final static VerticalPrintHelper Singleton =
	new VerticalPrintHelper();

    private VerticalPrintHelper()
    {
    }

    /**
     * Prints [] on System.out and stays on the same line of output.
     * @param host
     * @param input an Integer indicating the level of the node.
     * @return null
     */
    public Object emptyCase(BiTree host, Object input)
    {
	int level = ((Integer)input).intValue();

	printSpaces(level);
	System.out.print("[]");

	return null;
    }

    /**
     * Prints the host tree vertically on System.out and stays on
     * the same line of output as the last printed tree node.
     * @param host
     * @param input an Integer indicating the level of the node.
     * @return null
     */
    public Object nonEmptyCase(BiTree host, Object input)
    {
	int level = ((Integer)input).intValue();

	printSpaces(level);
	System.out.println(host.getRootData());

	level++;

	host.getLeftSubTree().execute(this, new Integer(level));
	System.out.println();

	host.getRightSubTree().execute(this, new Integer(level));

	return (null);
    }

    /**
     * Prints n spaces.
     */
    private void printSpaces(int n)
    {
	for (int i = 0; i < n; i++) {
	    System.out.print(' ');
	}
    }
}