#ifndef _sllist_
#define _sllist_

typedef struct sllist_node {
  struct sllist_node *next;
  void *val;
} Sllist_Node;

typedef struct sllist {
  Sllist_Node *head;
  Sllist_Node *tail;
} Sllist;

 
extern Sllist *new_sllist();
extern void free_sllist(Sllist *);
extern Sllist_Node *sll_prepend(Sllist *, void *);
extern Sllist_Node *sll_append(Sllist *, void *);
extern Sllist_Node *sll_insert_after(Sllist *, Sllist_Node *, void *);
extern Sllist_Node *sll_first(Sllist *);
extern Sllist_Node *sll_last(Sllist *);
extern Sllist_Node *sll_next(Sllist_Node *);
extern void *sll_val(Sllist_Node *);
extern int sll_empty(Sllist *);

#endif