Commit | Line | Data |
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984263bc MD |
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. | |
1de703da MD |
10 | * |
11 | * $NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $ | |
5d0641a4 | 12 | * $FreeBSD: src/lib/libc/stdlib/tsearch.c,v 1.4 2003/01/05 02:43:18 tjr Exp $ |
984263bc MD |
13 | */ |
14 | ||
984263bc MD |
15 | #define _SEARCH_PRIVATE |
16 | #include <search.h> | |
17 | #include <stdlib.h> | |
18 | ||
5d0641a4 PA |
19 | /* |
20 | * find or insert datum into search tree | |
8070fb31 SW |
21 | * |
22 | * Parameters: | |
23 | * vkey: key to be located | |
24 | * vrootp: address of tree root | |
25 | */ | |
5d0641a4 | 26 | |
984263bc | 27 | void * |
8070fb31 | 28 | tsearch(const void *vkey, void **vrootp, |
a2b8c067 | 29 | int (*compar)(const void *, const void *)) |
984263bc MD |
30 | { |
31 | node_t *q; | |
32 | node_t **rootp = (node_t **)vrootp; | |
33 | ||
34 | if (rootp == NULL) | |
35 | return NULL; | |
36 | ||
37 | while (*rootp != NULL) { /* Knuth's T1: */ | |
38 | int r; | |
39 | ||
40 | if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ | |
41 | return *rootp; /* we found it! */ | |
42 | ||
43 | rootp = (r < 0) ? | |
44 | &(*rootp)->llink : /* T3: follow left branch */ | |
45 | &(*rootp)->rlink; /* T4: follow right branch */ | |
46 | } | |
47 | ||
48 | q = malloc(sizeof(node_t)); /* T5: key not found */ | |
678e8cc6 | 49 | if (q != NULL) { /* make new node */ |
984263bc MD |
50 | *rootp = q; /* link new node to old */ |
51 | /* LINTED const castaway ok */ | |
3b5a5f3a | 52 | q->key = __DECONST(void *, vkey); /* initialize new node */ |
984263bc MD |
53 | q->llink = q->rlink = NULL; |
54 | } | |
55 | return q; | |
56 | } |