1 /* $OpenBSD: tfind.c,v 1.7 2015/09/26 16:03:48 guenther Exp $ */
2
3 /*
4 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
5 * the AT&T man page says.
6 *
7 * The node_t structure is for internal use only
8 *
9 * Written by reading the System V Interface Definition, not the code.
10 *
11 * Totally public domain.
12 */
13 #include <search.h>
14
15 typedef struct node_t
16 {
17 char *key;
18 struct node_t *llink, *rlink;
19 } node;
20
21 /* find a node, or return 0 */
22 void *
tfind(const void * vkey,void * const * vrootp,int (* compar)(const void *,const void *))23 tfind(const void *vkey, void * const *vrootp,
24 int (*compar)(const void *, const void *))
25 {
26 char *key = (char *)vkey;
27 node **rootp = (node **)vrootp;
28
29 if (rootp == (struct node_t **)0)
30 return ((struct node_t *)0);
31 while (*rootp != (struct node_t *)0) { /* T1: */
32 int r;
33 if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
34 return (*rootp); /* key found */
35 rootp = (r < 0) ?
36 &(*rootp)->llink : /* T3: follow left branch */
37 &(*rootp)->rlink; /* T4: follow right branch */
38 }
39 return (node *)0;
40 }
41