1 /* $NetBSD: tsearch.c,v 1.7 2012/06/25 22:32:45 abs 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: tsearch.c,v 1.7 2012/06/25 22:32:45 abs 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 /* find or insert datum into search tree */ 25 void * 26 tsearch(const void *vkey, void **vrootp, 27 int (*compar)(const void *, const void *)) 28 { 29 node_t *q; 30 node_t **rootp = (node_t **)vrootp; 31 32 _DIAGASSERT(vkey != NULL); 33 _DIAGASSERT(compar != NULL); 34 35 if (rootp == NULL) 36 return NULL; 37 38 while (*rootp != NULL) { /* Knuth's T1: */ 39 int r; 40 41 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 42 return *rootp; /* we found it! */ 43 44 rootp = (r < 0) ? 45 &(*rootp)->llink : /* T3: follow left branch */ 46 &(*rootp)->rlink; /* T4: follow right branch */ 47 } 48 49 q = malloc(sizeof(node_t)); /* T5: key not found */ 50 if (q != 0) { /* make new node */ 51 *rootp = q; /* link new node to old */ 52 q->key = __UNCONST(vkey); /* initialize new node */ 53 q->llink = q->rlink = NULL; 54 } 55 return q; 56 } 57
