/*      $OpenBSD: tfind.c,v 1.7 2015/09/26 16:03:48 guenther 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
 *
 * Written by reading the System V Interface Definition, not the code.
 *
 * Totally public domain.
 */
#include <search.h>

typedef struct node_t
{
    char          *key;
    struct node_t *llink, *rlink;
} node;

/* find a node, or return 0 */
void *
tfind(const void *vkey, void * const *vrootp,
    int (*compar)(const void *, const void *))
{
    char *key = (char *)vkey;
    node **rootp = (node **)vrootp;

    if (rootp == (struct node_t **)0)
        return ((struct node_t *)0);
    while (*rootp != (struct node_t *)0) {      /* T1: */
        int r;
        if ((r = (*compar)(key, (*rootp)->key)) == 0)   /* T2: */
            return (*rootp);            /* key found */
        rootp = (r < 0) ?
            &(*rootp)->llink :          /* T3: follow left branch */
            &(*rootp)->rlink;           /* T4: follow right branch */
    }
    return (node *)0;
}