1 /* $NetBSD: tdelete.c,v 1.3 1999/09/20 04:39:43 lukem Exp $ */
4 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
5 * the AT&T man page says.
7 * The node_t structure is for internal use only, lint doesn't grok it.
9 * Written by reading the System V Interface Definition, not the code.
11 * Totally public domain.
15 #define _SEARCH_PRIVATE
19 #define _DIAGASSERT assert
23 /* delete node with given key */
25 tdelete(const void *vkey, /* key to be deleted */
26 void **vrootp, /* address of the root of tree */
27 int (*compar)(const void *, const void *))
29 node_t **rootp = (node_t **)vrootp;
33 _DIAGASSERT(vkey != NULL);
34 _DIAGASSERT(compar != NULL);
36 if (rootp == NULL || (p = *rootp) == NULL)
39 while ((cmp = (*compar)(vkey, (*rootp)->key)) != 0) {
42 &(*rootp)->llink : /* follow llink branch */
43 &(*rootp)->rlink; /* follow rlink branch */
45 return NULL; /* key not found */
47 r = (*rootp)->rlink; /* D1: */
48 if ((q = (*rootp)->llink) == NULL) /* Left NULL? */
50 else if (r != NULL) { /* Right link is NULL? */
51 if (r->llink == NULL) { /* D2: Find successor */
54 } else { /* D3: Find NULL link */
55 for (q = r->llink; q->llink != NULL; q = r->llink)
58 q->llink = (*rootp)->llink;
59 q->rlink = (*rootp)->rlink;
62 free(*rootp); /* D4: Free node */
63 *rootp = q; /* link parent to new node */