lib/libc/stdlib/twalk.c

   1 /*      $NetBSD: twalk.c,v 1.4 2012/03/20 16:38:45 matt Exp $   */
   2
   3 /*
   4  * Tree search generalized from Knuth (6.2.2) Algorithm T just like
   5  * the AT&T man page says.
   6  *
   7  * The node_t structure is for internal use only, lint doesn't grok it.
   8  *
   9  * Written by reading the System V Interface Definition, not the code.
  10  *
  11  * Totally public domain.
  12  */
  13
  14 #include <sys/cdefs.h>
  15 #if defined(LIBC_SCCS) && !defined(lint)
  16 __RCSID("$NetBSD: twalk.c,v 1.4 2012/03/20 16:38:45 matt Exp $");
  17 #endif /* LIBC_SCCS and not lint */
  18
  19 #include <assert.h>
  20 #define _SEARCH_PRIVATE
  21 #include <search.h>
  22 #include <stdlib.h>
  23
  24 typedef void (*cmp_fn_t)(const void *, VISIT, int);
  25
  26 /* Walk the nodes of a tree */
  27 static void
  28 trecurse(const node_t *root,    /* Root of the tree to be walked */
  29         cmp_fn_t action, int level)
  30 {
  31         _DIAGASSERT(root != NULL);
  32         _DIAGASSERT(action != NULL);
  33
  34         if (root->llink == NULL && root->rlink == NULL)
  35                 (*action)(root, leaf, level);
  36         else {
  37                 (*action)(root, preorder, level);
  38                 if (root->llink != NULL)
  39                         trecurse(root->llink, action, level + 1);
  40                 (*action)(root, postorder, level);
  41                 if (root->rlink != NULL)
  42                         trecurse(root->rlink, action, level + 1);
  43                 (*action)(root, endorder, level);
  44         }
  45 }
  46
  47 /* Walk the nodes of a tree */
  48 void
  49 twalk(const void *vroot, cmp_fn_t action) /* Root of the tree to be walked */
  50 {
  51         if (vroot != NULL && action != NULL)
  52                 trecurse(vroot, action, 0);
  53 }