1 /* $NetBSD: tsearch.c,v 1.7 2012/06/25 22:32:45 abs 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, lint doesn't grok it.
8 *
9 * Written by reading the System V Interface Definition, not the code.
10 *
11 * Totally public domain.
12 */
13
14 #include <sys/cdefs.h>
15 #if 0
16 #if defined(LIBC_SCCS) && !defined(lint)
17 __RCSID("$NetBSD: tsearch.c,v 1.7 2012/06/25 22:32:45 abs Exp $");
18 #endif /* LIBC_SCCS and not lint */
19 #endif
20 __FBSDID("$FreeBSD$");
21
22 #define _SEARCH_PRIVATE
23 #include <search.h>
24 #include <stdlib.h>
25
26 /* find or insert datum into search tree */
27 void *
tsearch(const void * vkey,void ** vrootp,int (* compar)(const void *,const void *))28 tsearch(const void *vkey, void **vrootp,
29 int (*compar)(const void *, const void *))
30 {
31 node_t *q;
32 node_t **rootp = (node_t **)vrootp;
33
34 if (rootp == NULL)
35 return NULL;
36
37 while (*rootp != NULL) { /* Knuth's T1: */
38 int r;
39
40 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
41 return *rootp; /* we found it! */
42
43 rootp = (r < 0) ?
44 &(*rootp)->llink : /* T3: follow left branch */
45 &(*rootp)->rlink; /* T4: follow right branch */
46 }
47
48 q = malloc(sizeof(node_t)); /* T5: key not found */
49 if (q != 0) { /* make new node */
50 *rootp = q; /* link new node to old */
51 q->key = __DECONST(void *, vkey);/* initialize new node */
52 q->llink = q->rlink = NULL;
53 }
54 return q;
55 }
56