twalk.c revision 92905 
1/*	$NetBSD: twalk.c,v 1.1 1999/02/22 10:33:16 christos Exp $	*/
2/* $FreeBSD: head/lib/libc/stdlib/twalk.c 92905 2002-03-21 22:49:10Z obrien $ */
3
4/*
5 * Tree search generalized from Knuth (6.2.2) Algorithm T just like
6 * the AT&T man page says.
7 *
8 * The node_t structure is for internal use only, lint doesn't grok it.
9 *
10 * Written by reading the System V Interface Definition, not the code.
11 *
12 * Totally public domain.
13 */
14
15#include <sys/cdefs.h>
16#if defined(LIBC_SCCS) && !defined(lint)
17__RCSID("$NetBSD: twalk.c,v 1.1 1999/02/22 10:33:16 christos Exp $");
18#endif /* LIBC_SCCS and not lint */
19
20#include <assert.h>
21#define _SEARCH_PRIVATE
22#include <search.h>
23#include <stdlib.h>
24
25static void trecurse __P((const node_t *,
26    void  (*action)(const void *, VISIT, int), int level));
27
28/* Walk the nodes of a tree */
29static void
30trecurse(root, action, level)
31	const node_t *root;	/* Root of the tree to be walked */
32	void (*action)(const void *, VISIT, int);
33	int level;
34{
35
36	if (root->llink == NULL && root->rlink == NULL)
37		(*action)(root, leaf, level);
38	else {
39		(*action)(root, preorder, level);
40		if (root->llink != NULL)
41			trecurse(root->llink, action, level + 1);
42		(*action)(root, postorder, level);
43		if (root->rlink != NULL)
44			trecurse(root->rlink, action, level + 1);
45		(*action)(root, endorder, level);
46	}
47}
48
49/* Walk the nodes of a tree */
50void
51twalk(vroot, action)
52	const void *vroot;	/* Root of the tree to be walked */
53	void (*action)(const void *, VISIT, int);
54{
55	if (vroot != NULL && action != NULL)
56		trecurse(vroot, action, 0);
57}
58