/* Stack header file -- for pushing and popping generic data from a stack */

#include "jval.h"

typedef void *Stack;

extern Stack new_stack(); /*  allocates an empty stack. */
extern void stack_push(Stack s, Jval jv); /* pushes a new piece of data
					     onto the stack */
extern Jval stack_pop(Stack s); /* pops a value off the stack and returns it */
extern void free_stack(Stack s); /* destroy the stack and free memory */
extern Jval stack_top(Stack s); /* return the top value on the stack without
				   popping it */
extern int stack_empty(Stack s); /* return 1 if there are no elements on the
				    stack and 0 otherwise. */
extern int stack_size(Stack s); /* return the number of elements on the
				    stack */