#include <sys/queue.h>
SLIST_ENTRY(TYPE);
SLIST_HEAD(HEADNAME, TYPE);
SLIST_HEAD SLIST_HEAD_INITIALIZER(SLIST_HEAD head);
void SLIST_INIT(SLIST_HEAD *head);
int SLIST_EMPTY(SLIST_HEAD *head);
void SLIST_INSERT_HEAD(SLIST_HEAD *head,
struct TYPE *elm, SLIST_ENTRY NAME);
void SLIST_INSERT_AFTER(struct TYPE *listelm,
struct TYPE *elm, SLIST_ENTRY NAME);
struct TYPE *SLIST_FIRST(SLIST_HEAD *head);
struct TYPE *SLIST_NEXT(struct TYPE *elm, SLIST_ENTRY NAME);
SLIST_FOREACH(struct TYPE *var, SLIST_HEAD *head, SLIST_ENTRY NAME);
void SLIST_REMOVE(SLIST_HEAD *head, struct TYPE *elm,
SLIST_ENTRY NAME);
void SLIST_REMOVE_HEAD(SLIST_HEAD *head,
SLIST_ENTRY NAME);
In the macro definitions, TYPE is the name of a user-defined structure, that must contain a field of type SLIST_ENTRY, named NAME. The argument HEADNAME is the name of a user-defined structure that must be declared using the macro SLIST_HEAD().
SLIST_HEAD(HEADNAME, TYPE) head;
where struct HEADNAME is the structure to be defined, and struct TYPE is the type of the elements to be linked into the list. A pointer to the head of the list can later be declared as:
struct HEADNAME *headp;
(The names head and headp are user selectable.)
SLIST_ENTRY() declares a structure that connects the elements in the list.
SLIST_HEAD_INITIALIZER() evaluates to an initializer for the list head.
SLIST_INIT() initializes the list referenced by head.
SLIST_EMPTY() evaluates to true if there are no elements in the list.
SLIST_INSERT_AFTER() inserts the new element elm after the element listelm.
SLIST_NEXT() returns the next element in the list.
SLIST_FOREACH() traverses the list referenced by head in the forward direction, assigning each element in turn to var.
SLIST_REMOVE_HEAD() removes the element elm from the head of the list. For optimum efficiency, elements being removed from the head of the list should explicitly use this macro instead of the generic SLIST_REMOVE().
SLIST_FIRST(), and SLIST_NEXT() return a pointer to the first or next TYPE structure, respectively.
SLIST_HEAD_INITIALIZER() returns an initializer that can be assigned to the list head.
struct entry {
int data;
SLIST_ENTRY(entry) entries; /* Singly linked list */
};
SLIST_HEAD(slisthead, entry);
int
main(void)
{
struct entry *n1, *n2, *n3, *np;
struct slisthead head; /* Singly linked list
head */
SLIST_INIT(&head); /* Initialize the queue */
n1 = malloc(sizeof(struct entry)); /* Insert at the head */
SLIST_INSERT_HEAD(&head, n1, entries);
n2 = malloc(sizeof(struct entry)); /* Insert after */
SLIST_INSERT_AFTER(n1, n2, entries);
SLIST_REMOVE(&head, n2, entry, entries);/* Deletion */
free(n2);
n3 = SLIST_FIRST(&head);
SLIST_REMOVE_HEAD(&head, entries); /* Deletion from the head */
free(n3);
for (int i = 0; i < 5; i++) {
n1 = malloc(sizeof(struct entry));
SLIST_INSERT_HEAD(&head, n1, entries);
n1->data = i;
}
/* Forward traversal */
SLIST_FOREACH(np, &head, entries)
printf("%i\n", np->data);
while (!SLIST_EMPTY(&head)) { /* List deletion */
n1 = SLIST_FIRST(&head);
SLIST_REMOVE_HEAD(&head, entries);
free(n1);
}
SLIST_INIT(&head);