1 /* 2 * Tree search generalized from Knuth (6.2.2) Algorithm T just like 3 * the AT&T man page says. 4 * 5 * The node_t structure is for internal use only, lint doesn't grok it. 6 * 7 * Written by reading the System V Interface Definition, not the code. 8 * 9 * Totally public domain. 10 */ 11 /*LINTLIBRARY*/ 12 #include <search.h> 13 14 typedef struct node_t 15 { 16 char *key; 17 struct node_t *llink, *rlink; 18 } node; 19 20 /* find a node, or return 0 */ 21 void * 22 tfind(vkey, vrootp, compar) 23 const void *vkey; /* key to be found */ 24 void *const *vrootp; /* address of the tree root */ 25 int (*compar) __P((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