/*

   Purpose:

     This program illustrates recursive invocations and the

     stacking of those invocations. It includes the definition and use

     of a simple recursive method that just produces illustrative

     output.



   Record of revisions:

	Date                Programmer          Description of change

	====                ==========          =====================

	March 2003          J. Rodger           Original coding

	May 2003            J. Rodger           hsa I/O, user input for depth

*/



// The "ShowRecursion" class.

import hsa.*;

public class ShowRecursion

{

    // static (global) variable to keep track of calls

    public static int stack = 0;    // stack depth



    // helper to show stack growth, shrinkage

    public static void tabOver (int n)

    {

	for (int i = 0 ; i < n ; i++)

	    Stdout.print ("    ");

    } // tabOver





    // method that does nothing but illustrate stacking

    // of recursive invocations

    // uses global variable to track stack depth

    public static void stacker (int n)

    {

	stack++;

	// print stack depth increasing

	tabOver (stack);

	Stdout.print ("Stack depth:" + stack);

	if (n == 0)

	{

	    Stdout.println (", n=0, base case, recursion ends");

	}

	else

	{

	    Stdout.println (", n=" + n + " recurse with n=" + (n - 1));

	    stacker (n - 1);

	}

	// print stack depth decreasing

	tabOver (stack);

	Stdout.print ("Stack depth:" + stack);

	Stdout.println (", invocation with n=" + n + " terminates");

	stack--;

    } // end stacker





    public static void main (String [] args)

    {

	int x;      // positive integer for stack illustration

	Stdout.print ("Enter small positive integer for recursive stack depth:");

	x = Stdin.readInt ();



	Stdout.println ("Simple illustration of recursive stack for x:" + x);

	stacker (x);

	Stdout.println ("Recursion ends, back to main method.");



    } // main method

} // ShowRecursion class