/*--------------------------------------------------------------------*/
/* stackao.h                                                          */
/* Author: Bob Dondero                                                */
/* A Stack abstract object interface                                  */
/*--------------------------------------------------------------------*/

#ifndef STACKAO_INCLUDED
#define STACKAO_INCLUDED

/* The Stack is a last-in-first-out collection of doubles. */

void Stack_init(void);
/* Initialize the Stack.
   It is a checked runtime error for the Stack to be initialized. */

void Stack_free(void);
/* Free the resources consumed by the Stack.
   It is a checked runtime error for the Stack to be uninitialized. */

void Stack_push(double dItem);
/* Push dItem onto the Stack.
   It is a checked runtime error for the Stack to be uninitialized. */

double Stack_top(void);
/* Return the top item of the Stack.
   It is a checked runtime error for the Stack to be uninitialized or
   empty. */

void Stack_pop(void);
/* Pop the Stack, and discard the popped item.
   It is a checked runtime error for the Stack to be uninitialized or
   empty. */

int Stack_isEmpty(void);
/* Return 1 (TRUE) iff the Stack is empty.
   It is a checked runtime error for the Stack to be uninitialized. */

#endif