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1 | /* $Id$ | |
2 | * | |
3 | * Generic hash table routines. Uses integer keys to store char * values. | |
4 | * | |
5 | * Copyright (C) 1988-1998 by the Massachusetts Institute of Technology. | |
6 | * For copying and distribution information, please see the file | |
7 | * <mit-copyright.h>. | |
8 | */ | |
9 | ||
10 | #include <mit-copyright.h> | |
11 | #include <moira.h> | |
12 | ||
13 | #include <stdlib.h> | |
14 | #include <string.h> | |
15 | ||
16 | RCSID("$Header$"); | |
17 | ||
18 | #define hash_func(h, key) (key >= 0 ? (key % h->size) : (-key % h->size)) | |
19 | ||
20 | /* Create a hash table. The size is just a hint, not a maximum. */ | |
21 | ||
22 | struct hash *create_hash(int size) | |
23 | { | |
24 | struct hash *h; | |
25 | ||
26 | h = malloc(sizeof(struct hash)); | |
27 | if (!h) | |
28 | return NULL; | |
29 | h->size = size; | |
30 | h->data = malloc(size * sizeof(void *)); | |
31 | if (!h->data) | |
32 | { | |
33 | free(h); | |
34 | return NULL; | |
35 | } | |
36 | memset(h->data, 0, size * sizeof(void *)); | |
37 | return h; | |
38 | } | |
39 | ||
40 | /* Lookup an object in the hash table. Returns the value associated with | |
41 | * the key, or NULL (thus NULL is not a very good value to store...) | |
42 | */ | |
43 | ||
44 | void *hash_lookup(struct hash *h, int key) | |
45 | { | |
46 | struct bucket *b; | |
47 | ||
48 | b = h->data[hash_func(h, key)]; | |
49 | while (b && b->key != key) | |
50 | b = b->next; | |
51 | if (b && b->key == key) | |
52 | return b->data; | |
53 | else | |
54 | return NULL; | |
55 | } | |
56 | ||
57 | ||
58 | /* Update an existing object in the hash table. Returns 1 if the object | |
59 | * existed, or 0 if not. | |
60 | */ | |
61 | ||
62 | int hash_update(struct hash *h, int key, void *value) | |
63 | { | |
64 | struct bucket *b; | |
65 | ||
66 | b = h->data[hash_func(h, key)]; | |
67 | while (b && b->key != key) | |
68 | b = b->next; | |
69 | if (b && b->key == key) | |
70 | { | |
71 | b->data = value; | |
72 | return 1; | |
73 | } | |
74 | else | |
75 | return 0; | |
76 | } | |
77 | ||
78 | ||
79 | /* Store an item in the hash table. Returns 0 if the key was not previously | |
80 | * there, 1 if it was, or -1 if we ran out of memory. | |
81 | */ | |
82 | ||
83 | int hash_store(struct hash *h, int key, void *value) | |
84 | { | |
85 | struct bucket *b, **p; | |
86 | ||
87 | p = &(h->data[hash_func(h, key)]); | |
88 | if (!*p) | |
89 | { | |
90 | b = *p = malloc(sizeof(struct bucket)); | |
91 | if (!b) | |
92 | return -1; | |
93 | b->next = NULL; | |
94 | b->key = key; | |
95 | b->data = value; | |
96 | return 0; | |
97 | } | |
98 | ||
99 | for (b = *p; b && b->key != key; b = *p) | |
100 | p = (struct bucket **) *p; | |
101 | if (b && b->key == key) | |
102 | { | |
103 | b->data = value; | |
104 | return 1; | |
105 | } | |
106 | b = *p = malloc(sizeof(struct bucket)); | |
107 | if (!b) | |
108 | return -1; | |
109 | b->next = NULL; | |
110 | b->key = key; | |
111 | b->data = value; | |
112 | return 0; | |
113 | } | |
114 | ||
115 | ||
116 | /* Search through the hash table for a given value. For each piece of | |
117 | * data with that value, call the callback proc with the corresponding key. | |
118 | */ | |
119 | ||
120 | void hash_search(struct hash *h, void *value, void (*callback)(int)) | |
121 | { | |
122 | struct bucket *b, **p; | |
123 | ||
124 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) | |
125 | { | |
126 | for (b = *p; b; b = b->next) | |
127 | { | |
128 | if (b->data == value) | |
129 | (*callback)(b->key); | |
130 | } | |
131 | } | |
132 | } | |
133 | ||
134 | ||
135 | /* Step through the hash table, calling the callback proc with each key. | |
136 | */ | |
137 | ||
138 | void hash_step(struct hash *h, void (*callback)(int, void *, void *), | |
139 | void *hint) | |
140 | { | |
141 | struct bucket *b, **p; | |
142 | ||
143 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) | |
144 | { | |
145 | for (b = *p; b; b = b->next) | |
146 | (*callback)(b->key, b->data, hint); | |
147 | } | |
148 | } | |
149 | ||
150 | ||
151 | /* Deallocate all of the memory associated with a table */ | |
152 | ||
153 | void hash_destroy(struct hash *h) | |
154 | { | |
155 | struct bucket *b, **p, *b1; | |
156 | ||
157 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) | |
158 | { | |
159 | for (b = *p; b; b = b1) | |
160 | { | |
161 | b1 = b->next; | |
162 | free(b); | |
163 | } | |
164 | } | |
165 | } |