stack.h

#ifndef _STACK_H_
#define _STACK_H_

/*
 *
 * stack.h
 * Created by: Nayef Copty
 *
 * A stack implementation that does not require dynamic memory allocation.
 *
 * The stack can hold any structure that embeds a struct stack_elem.
 * Inspired by GNU List and the list<> template in the C++ standard library.
 *
 */

#include <stdint.h>
#include <stddef.h>

struct stack_elem {
    struct stack_elem *next;
};

struct stack {
    struct stack_elem *top;
};

/*
 * Converts a pointer to the stack's element ptr into a pointer
 * to the structure that ptr is embedded inside. Supply the name
 * of the outer struct, 'type', and the member name of the stack
 * element 'member'. Taken from the Linux kernel container_of().
 */
#define stack_entry(ptr, type, member) ({ \
	    const typeof( ((type *)0)->member ) *__mptr = (ptr); \
	    (type *)( (char *)__mptr - offsetof(type,member) );})

void stack_init(struct stack *stack);
void push(struct stack *stack, struct stack_elem *elem);
struct stack_elem * pop(struct stack *);
struct stack_elem * peek(struct stack *);
int count(struct stack *);
int isEmpty(struct stack *);

/*
 * Returns a stack with the cleared nodes contained.
 * You must iterate through the stack, convert the pointers
 * and free the pointers manually.
 */
struct stack clear(struct stack *);

#endif /* stack.h */