1 /* $OpenBSD: tfind.c,v 1.6 2014/03/16 18:38:30 guenther 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 8 * 9 * Written by reading the System V Interface Definition, not the code. 10 * 11 * Totally public domain. 12 */ 13 /*LINTLIBRARY*/ 14 #include <search.h> 15 16 typedef struct node_t 17 { 18 char *key; 19 struct node_t *llink, *rlink; 20 } node; 21 22 /* find a node, or return 0 */ 23 void * 24 tfind(const void *vkey, void * const *vrootp, 25 int (*compar)(const void *, const void *)) 26 { 27 char *key = (char *)vkey; 28 node **rootp = (node **)vrootp; 29 30 if (rootp == (struct node_t **)0) 31 return ((struct node_t *)0); 32 while (*rootp != (struct node_t *)0) { /* T1: */ 33 int r; 34 if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */ 35 return (*rootp); /* key found */ 36 rootp = (r < 0) ? 37 &(*rootp)->llink : /* T3: follow left branch */ 38 &(*rootp)->rlink; /* T4: follow right branch */ 39 } 40 return (node *)0; 41 } 42
