1 /* $OpenBSD: tfind.c,v 1.6 2014/03/16 18:38:30 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 /*LINTLIBRARY*/
14 #include <search.h>
15
16 typedef struct node_t
17 {
18 char *key;
19 struct node_t *llink, *rlink;
20 } node;
21
22 /* find a node, or return 0 */
23 void *
tfind(const void * vkey,void * const * vrootp,int (* compar)(const void *,const void *))24 tfind(const void *vkey, void * const *vrootp,
25 int (*compar)(const void *, const void *))
26 {
27 char *key = (char *)vkey;
28 node **rootp = (node **)vrootp;
29
30 if (rootp == (struct node_t **)0)
31 return ((struct node_t *)0);
32 while (*rootp != (struct node_t *)0) { /* T1: */
33 int r;
34 if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
35 return (*rootp); /* key found */
36 rootp = (r < 0) ?
37 &(*rootp)->llink : /* T3: follow left branch */
38 &(*rootp)->rlink; /* T4: follow right branch */
39 }
40 return (node *)0;
41 }
42