1 /* $NetBSD: tdelete.c,v 1.4 2006/03/19 01:12:08 christos 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.
14 #define _SEARCH_PRIVATE
23 /* delete node with given key */
25 tdelete(vkey, vrootp, compar)
26 const void *vkey; /* key to be deleted */
27 void **vrootp; /* address of the root of tree */
28 int (*compar) (const void *, const void *);
30 node_t **rootp = (node_t **)vrootp;
35 assert(compar != NULL);
37 if (rootp == NULL || (p = *rootp) == NULL)
40 while ((cmp = (*compar)(vkey, (*rootp)->key)) != 0) {
43 &(*rootp)->llink : /* follow llink branch */
44 &(*rootp)->rlink; /* follow rlink branch */
46 return NULL; /* key not found */
48 r = (*rootp)->rlink; /* D1: */
49 if ((q = (*rootp)->llink) == NULL) /* Left NULL? */
51 else if (r != NULL) { /* Right link is NULL? */
52 if (r->llink == NULL) { /* D2: Find successor */
55 } else { /* D3: Find NULL link */
56 for (q = r->llink; q->llink != NULL; q = r->llink)
59 q->llink = (*rootp)->llink;
60 q->rlink = (*rootp)->rlink;
64 free(*rootp); /* D4: Free node */
65 *rootp = q; /* link parent to new node */