tsearch.c revision 92905
162321Salfred/* $NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $ */ 262321Salfred/* $FreeBSD: head/lib/libc/stdlib/tsearch.c 92905 2002-03-21 22:49:10Z obrien $ */ 362321Salfred 462321Salfred/* 562321Salfred * Tree search generalized from Knuth (6.2.2) Algorithm T just like 662321Salfred * the AT&T man page says. 762321Salfred * 862321Salfred * The node_t structure is for internal use only, lint doesn't grok it. 962321Salfred * 1062321Salfred * Written by reading the System V Interface Definition, not the code. 1162321Salfred * 1262321Salfred * Totally public domain. 1362321Salfred */ 1462321Salfred 1562321Salfred#include <sys/cdefs.h> 1662321Salfred#if defined(LIBC_SCCS) && !defined(lint) 1762321Salfred__RCSID("$NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $"); 1862321Salfred#endif /* LIBC_SCCS and not lint */ 1962321Salfred 2062321Salfred#include <assert.h> 2162321Salfred#define _SEARCH_PRIVATE 2262321Salfred#include <search.h> 2362321Salfred#include <stdlib.h> 2462321Salfred 2562321Salfred/* find or insert datum into search tree */ 2662321Salfredvoid * 2762321Salfredtsearch(vkey, vrootp, compar) 2862321Salfred const void *vkey; /* key to be located */ 2962321Salfred void **vrootp; /* address of tree root */ 3092905Sobrien int (*compar)(const void *, const void *); 3162321Salfred{ 3262321Salfred node_t *q; 3362321Salfred node_t **rootp = (node_t **)vrootp; 3462321Salfred 3562321Salfred if (rootp == NULL) 3662321Salfred return NULL; 3762321Salfred 3862321Salfred while (*rootp != NULL) { /* Knuth's T1: */ 3962321Salfred int r; 4062321Salfred 4162321Salfred if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 4262321Salfred return *rootp; /* we found it! */ 4362321Salfred 4462321Salfred rootp = (r < 0) ? 4562321Salfred &(*rootp)->llink : /* T3: follow left branch */ 4662321Salfred &(*rootp)->rlink; /* T4: follow right branch */ 4762321Salfred } 4862321Salfred 4962321Salfred q = malloc(sizeof(node_t)); /* T5: key not found */ 5062321Salfred if (q != 0) { /* make new node */ 5162321Salfred *rootp = q; /* link new node to old */ 5262321Salfred /* LINTED const castaway ok */ 5362321Salfred q->key = (void *)vkey; /* initialize new node */ 5462321Salfred q->llink = q->rlink = NULL; 5562321Salfred } 5662321Salfred return q; 5762321Salfred} 58