/*--------------------------------------------------------------------*/
/* stack.h                                                            */
/* Author: Bob Dondero                                                */
/* A generic 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 items. */

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

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

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

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

void Stack_pop(Stack_T oStack);
/* Pop oStack, and discard 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