blob: d3d6e7e88d386b2cbca32a49419d933048f1bd45 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
/* $NetBSD: tdelete.c,v 1.2 1999/09/16 11:45:37 lukem Exp $ */
/*
* Tree search generalized from Knuth (6.2.2) Algorithm T just like
* the AT&T man page says.
*
* The node_t structure is for internal use only, lint doesn't grok it.
*
* Written by reading the System V Interface Definition, not the code.
*
* Totally public domain.
*/
#include <sys/cdefs.h>
#if 0
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: tdelete.c,v 1.2 1999/09/16 11:45:37 lukem Exp $");
#endif /* LIBC_SCCS and not lint */
#endif
__FBSDID("$FreeBSD$");
#include <assert.h>
#define _SEARCH_PRIVATE
#include <search.h>
#include <stdlib.h>
/*
* delete node with given key
*
* vkey: key to be deleted
* vrootp: address of the root of the tree
* compar: function to carry out node comparisons
*/
void *
tdelete(const void * __restrict vkey, void ** __restrict vrootp,
int (*compar)(const void *, const void *))
{
node_t **rootp = (node_t **)vrootp;
node_t *p, *q, *r;
int cmp;
if (rootp == NULL || (p = *rootp) == NULL)
return NULL;
while ((cmp = (*compar)(vkey, (*rootp)->key)) != 0) {
p = *rootp;
rootp = (cmp < 0) ?
&(*rootp)->llink : /* follow llink branch */
&(*rootp)->rlink; /* follow rlink branch */
if (*rootp == NULL)
return NULL; /* key not found */
}
r = (*rootp)->rlink; /* D1: */
if ((q = (*rootp)->llink) == NULL) /* Left NULL? */
q = r;
else if (r != NULL) { /* Right link is NULL? */
if (r->llink == NULL) { /* D2: Find successor */
r->llink = q;
q = r;
} else { /* D3: Find NULL link */
for (q = r->llink; q->llink != NULL; q = r->llink)
r = q;
r->llink = q->rlink;
q->llink = (*rootp)->llink;
q->rlink = (*rootp)->rlink;
}
}
free(*rootp); /* D4: Free node */
*rootp = q; /* link parent to new node */
return p;
}
|
