/*------------------------------------------------------------------*/
/* stack.h                                                          */
/* Author: Bob Dondero                                              */
/* A Stack ADT interface                                            */
/*------------------------------------------------------------------*/

#ifndef STACK_INCLUDED
#define STACK_INCLUDED

typedef struct Stack *Stack_T;
/* A Stack_T is a last-in-first-out collection of doubles. */

Stack_T Stack_new(void);
/* Return a new Stack_T. */

void Stack_free(Stack_T oStack);
/* Free oStack. */

void Stack_push(Stack_T oStack, double dItem);
/* Push dItem onto oStack.
   It is a checked runtime error for oStack to be NULL. */

double Stack_pop(Stack_T oStack);
/* Pop oStack, and return the popped item.
   It is a checked runtime error for oStack to be NULL or empty. */

int Stack_isEmpty(Stack_T oStack);
/* Return 1 (TRUE) iff oStack is empty.
   It is a checked runtime error for oStack to be NULL. */

#endif