1 /* $NetBSD: tdelete.c,v 1.2 1999/09/16 11:45:37 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.
14 #include <sys/cdefs.h>
16 #if defined(LIBC_SCCS) && !defined(lint)
17 __RCSID("$NetBSD: tdelete.c,v 1.2 1999/09/16 11:45:37 lukem Exp $");
18 #endif /* LIBC_SCCS and not lint */
20 __FBSDID("$FreeBSD$");
22 #define _SEARCH_PRIVATE
28 * delete node with given key
30 * vkey: key to be deleted
31 * vrootp: address of the root of the tree
32 * compar: function to carry out node comparisons
35 tdelete(const void * __restrict vkey, void ** __restrict vrootp,
36 int (*compar)(const void *, const void *))
38 node_t **rootp = (node_t **)vrootp;
42 if (rootp == NULL || (p = *rootp) == NULL)
45 while ((cmp = (*compar)(vkey, (*rootp)->key)) != 0) {
48 &(*rootp)->llink : /* follow llink branch */
49 &(*rootp)->rlink; /* follow rlink branch */
51 return NULL; /* key not found */
53 r = (*rootp)->rlink; /* D1: */
54 if ((q = (*rootp)->llink) == NULL) /* Left NULL? */
56 else if (r != NULL) { /* Right link is NULL? */
57 if (r->llink == NULL) { /* D2: Find successor */
60 } else { /* D3: Find NULL link */
61 for (q = r->llink; q->llink != NULL; q = r->llink)
64 q->llink = (*rootp)->llink;
65 q->rlink = (*rootp)->rlink;
68 free(*rootp); /* D4: Free node */
69 *rootp = q; /* link parent to new node */