/*      $NetBSD: tsearch.c,v 1.7 2012/06/25 22:32:45 abs 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 defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: tsearch.c,v 1.7 2012/06/25 22:32:45 abs Exp $");
#endif /* LIBC_SCCS and not lint */

#include <assert.h>
#define _SEARCH_PRIVATE
#include <search.h>
#include <stdlib.h>

/* find or insert datum into search tree */
void *
tsearch(const void *vkey, void **vrootp,
   int (*compar)(const void *, const void *))
{
       node_t *q;
       node_t **rootp = (node_t **)vrootp;

       _DIAGASSERT(vkey != NULL);
       _DIAGASSERT(compar != NULL);

       if (rootp == NULL)
               return NULL;

       while (*rootp != NULL) {        /* Knuth's T1: */
               int r;

               if ((r = (*compar)(vkey, (*rootp)->key)) == 0)  /* T2: */
                       return *rootp;          /* we found it! */

               rootp = (r < 0) ?
                   &(*rootp)->llink :          /* T3: follow left branch */
                   &(*rootp)->rlink;           /* T4: follow right branch */
       }

       q = malloc(sizeof(node_t));             /* T5: key not found */
       if (q != 0) {                           /* make new node */
               *rootp = q;                     /* link new node to old */
               q->key = __UNCONST(vkey);       /* initialize new node */
               q->llink = q->rlink = NULL;
       }
       return q;
}