1#include <stdlib.h>
2#include <search.h>
3#include "tsearch.h"
4
5void *tdelete(const void *restrict key, void **restrict rootp,
6 int(*cmp)(const void *, const void *))
7{
8 if (!rootp)
9 return 0;
10
11 void **a[MAXH+1];
12 struct node *n = *rootp;
13 struct node *parent;
14 struct node *child;
15 int i=0;
16 /* *a[0] is an arbitrary non-null pointer that is returned when
17 the root node is deleted. */
18 a[i++] = rootp;
19 a[i++] = rootp;
20 for (;;) {
21 if (!n)
22 return 0;
23 int c = cmp(key, n->key);
24 if (!c)
25 break;
26 a[i++] = &n->a[c>0];
27 n = n->a[c>0];
28 }
29 parent = *a[i-2];
30 if (n->a[0]) {
31 /* free the preceding node instead of the deleted one. */
32 struct node *deleted = n;
33 a[i++] = &n->a[0];
34 n = n->a[0];
35 while (n->a[1]) {
36 a[i++] = &n->a[1];
37 n = n->a[1];
38 }
39 deleted->key = n->key;
40 child = n->a[0];
41 } else {
42 child = n->a[1];
43 }
44 /* freed node has at most one child, move it up and rebalance. */
45 free(n);
46 *a[--i] = child;
47 while (--i && __tsearch_balance(a[i]));
48 return parent;
49}