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 defined(LIBC_SCCS) && !defined(lint)
16 __RCSID("$NetBSD: tsearch.c,v 1.7 2012/06/25 22:32:45 abs Exp $");
17 #endif /* LIBC_SCCS and not lint */
18
19 #include <assert.h>
20 #define _SEARCH_PRIVATE
21 #include <search.h>
22 #include <stdlib.h>
23
24 /* find or insert datum into search tree */
25 void *
tsearch(const void * vkey,void ** vrootp,int (* compar)(const void *,const void *))26 tsearch(const void *vkey, void **vrootp,
27 int (*compar)(const void *, const void *))
28 {
29 node_t *q;
30 node_t **rootp = (node_t **)vrootp;
31
32 _DIAGASSERT(vkey != NULL);
33 _DIAGASSERT(compar != NULL);
34
35 if (rootp == NULL)
36 return NULL;
37
38 while (*rootp != NULL) { /* Knuth's T1: */
39 int r;
40
41 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
42 return *rootp; /* we found it! */
43
44 rootp = (r < 0) ?
45 &(*rootp)->llink : /* T3: follow left branch */
46 &(*rootp)->rlink; /* T4: follow right branch */
47 }
48
49 q = malloc(sizeof(node_t)); /* T5: key not found */
50 if (q != 0) { /* make new node */
51 *rootp = q; /* link new node to old */
52 q->key = __UNCONST(vkey); /* initialize new node */
53 q->llink = q->rlink = NULL;
54 }
55 return q;
56 }
57