#ifndef __STACK_H__
#define __STACK_H__

#include "utlist.h"

typedef struct _abac_stack_t abac_stack_t;
typedef struct _abac_stack_element_t abac_stack_element_t;

struct _abac_stack_element_t {
    void *ptr;
    abac_stack_element_t *prev, *next;
};

struct _abac_stack_t {
    abac_stack_element_t *elts;
    int size;
};

abac_stack_t *abac_stack_new(void);
void abac_stack_push(abac_stack_t *stack, void *elt);
int abac_stack_unique_push(abac_stack_t *stack, void *elt);
void *abac_stack_pop(abac_stack_t *stack);
int abac_stack_size(abac_stack_t *stack);
void abac_stack_free(abac_stack_t *stack);

#define abac_stack_foreach(STACK, CURRENT, BODY) do {  \
    abac_stack_element_t *_elt;                  \
    DL_FOREACH(STACK->elts, _elt) {              \
        CURRENT = (typeof(CURRENT))_elt->ptr;   \
        BODY                                    \
    }                                           \
} while (0)

#endif /* __STACK_H__ */