// genstack.h Definition of the generic Stack class and generic
//   implementation functions.

#include <stdlib.h>
#include <iostream.h>

const char BOTTOM = 'b';
const char EXPREND = '#';
const char NUMBER = 'n';
const int MAX = 100;

template <class AnyType>
class Stack
{	public:	Stack ();					// constructor
				void Push (AnyType x);	// push x onto stack
				AnyType Pop ();			// pop and return top item
				AnyType Top ();			// return a copy of top item
	private:	AnyType cells[MAX];		// allow MAX entries
				int current_top;			// index of current top
				void Serror (char *);	// error message function
};

template <class AnyType>
Stack<AnyType>::Stack ()
{ current_top = 0;
}

template <class AnyType>
void Stack<AnyType>::Serror (char *errmes)
{	cerr << errmes << endl;
	exit(0);
}

template <class AnyType>
void Stack<AnyType>::Push (AnyType x)
{	if (current_top <= MAX)
		cells[current_top++] = x;
	else Serror("stack overflow");
}

template <class AnyType>
AnyType Stack<AnyType>::Pop ()
{	if (current_top == 0)
		Serror ("stack underflow");
	return (cells[--current_top]);
}

template <class AnyType>
AnyType Stack<AnyType>::Top ()
{	return (cells[current_top -1]);
}