| /* $NetBSD: tsearch.c,v 1.4 1999/09/20 04:39:43 lukem 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, lint doesn't grok it. |
| * |
| * Written by reading the System V Interface Definition, not the code. |
| * |
| * Totally public domain. |
| */ |
| |
| #include <assert.h> |
| #define _SEARCH_PRIVATE |
| #include <search.h> |
| #include <stdlib.h> |
| |
| |
| /* find or insert datum into search tree */ |
| void * |
| tsearch(const void * __restrict__ vkey, /* key to be located */ |
| void ** __restrict__ vrootp, /* address of tree root */ |
| int (*compar) (const void *, const void *)) |
| { |
| node_t *q; |
| node_t **rootp = (node_t **)vrootp; |
| |
| if (rootp == NULL) |
| return NULL; |
| |
| while (*rootp != NULL) { /* Knuth's T1: */ |
| int r; |
| |
| if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ |
| return *rootp; /* we found it! */ |
| |
| rootp = (r < 0) ? |
| &(*rootp)->llink : /* T3: follow left branch */ |
| &(*rootp)->rlink; /* T4: follow right branch */ |
| } |
| |
| q = malloc(sizeof(node_t)); /* T5: key not found */ |
| if (q != 0) { /* make new node */ |
| *rootp = q; /* link new node to old */ |
| /* LINTED const castaway ok */ |
| q->key = (void *)vkey; /* initialize new node */ |
| q->llink = q->rlink = NULL; |
| } |
| return q; |
| } |