1 /*
2 Copyright (c) 1991, 1993, 1994
3 The Regents of the University of California. All rights reserved.
4
5 Redistribution and use in source and binary forms, with or without
6 modification, are permitted provided that the following conditions
7 are met:
8 1. Redistributions of source code must retain the above copyright
9 notice, this list of conditions and the following disclaimer.
10 2. Redistributions in binary form must reproduce the above copyright
11 notice, this list of conditions and the following disclaimer in the
12 documentation and/or other materials provided with the distribution.
13 3. Neither the name of the University nor the names of its contributors
14 may be used to endorse or promote products derived from this software
15 without specific prior written permission.
16
17 THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 SUCH DAMAGE.
28 */
29 /* $NetBSD: tdelete.c,v 1.2 1999/09/16 11:45:37 lukem Exp $ */
30
31 /*
32 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
33 * the AT&T man page says.
34 *
35 * The node_t structure is for internal use only, lint doesn't grok it.
36 *
37 * Written by reading the System V Interface Definition, not the code.
38 *
39 * Totally public domain.
40 */
41
42 #include <sys/cdefs.h>
43 #if 0
44 #if defined(LIBC_SCCS) && !defined(lint)
45 __RCSID("$NetBSD: tdelete.c,v 1.2 1999/09/16 11:45:37 lukem Exp $");
46 #endif /* LIBC_SCCS and not lint */
47 #endif
48
49 #include <assert.h>
50 #define _SEARCH_PRIVATE
51 #include <search.h>
52 #include <stdlib.h>
53
54
55 /* delete node with given key */
56 void *
tdelete(const void * __restrict vkey,void ** __restrict vrootp,int (* compar)(const void *,const void *))57 tdelete (const void *__restrict vkey, /* key to be deleted */
58 void **__restrict vrootp, /* address of the root of tree */
59 int (*compar)(const void *, const void *))
60 {
61 node_t **rootp = (node_t **)vrootp;
62 node_t *p, *q, *r;
63 int cmp;
64
65 if (rootp == NULL || (p = *rootp) == NULL)
66 return NULL;
67
68 while ((cmp = (*compar)(vkey, (*rootp)->key)) != 0) {
69 p = *rootp;
70 rootp = (cmp < 0) ?
71 &(*rootp)->llink : /* follow llink branch */
72 &(*rootp)->rlink; /* follow rlink branch */
73 if (*rootp == NULL)
74 return NULL; /* key not found */
75 }
76 r = (*rootp)->rlink; /* D1: */
77 if ((q = (*rootp)->llink) == NULL) /* Left NULL? */
78 q = r;
79 else if (r != NULL) { /* Right link is NULL? */
80 if (r->llink == NULL) { /* D2: Find successor */
81 r->llink = q;
82 q = r;
83 } else { /* D3: Find NULL link */
84 for (q = r->llink; q->llink != NULL; q = r->llink)
85 r = q;
86 r->llink = q->rlink;
87 q->llink = (*rootp)->llink;
88 q->rlink = (*rootp)->rlink;
89 }
90 }
91 free(*rootp); /* D4: Free node */
92 *rootp = q; /* link parent to new node */
93 return p;
94 }
95
