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Commit | Line | Data |
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fa59b86f | 1 | /* $Id$ |
b93ad422 | 2 | * |
3 | * Generic hash table routines. Uses integer keys to store char * values. | |
babbc197 | 4 | * |
7ac48069 | 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>. | |
b93ad422 | 8 | */ |
9 | ||
babbc197 | 10 | #include <mit-copyright.h> |
8defc06b | 11 | #include <moira.h> |
7ac48069 | 12 | |
a43ce477 | 13 | #include <stdlib.h> |
7ac48069 | 14 | #include <string.h> |
15 | ||
16 | RCSID("$Header$"); | |
d9e7aa31 | 17 | |
8e24e9aa | 18 | #define hash_func(h, key) (key >= 0 ? (key % h->size) : (-key % h->size)) |
b93ad422 | 19 | |
20 | /* Create a hash table. The size is just a hint, not a maximum. */ | |
21 | ||
5eaef520 | 22 | struct hash *create_hash(int size) |
b93ad422 | 23 | { |
5eaef520 | 24 | struct hash *h; |
25 | ||
26 | h = malloc(sizeof(struct hash)); | |
27 | if (!h) | |
28 | return NULL; | |
29 | h->size = size; | |
7ac48069 | 30 | h->data = malloc(size * sizeof(void *)); |
5eaef520 | 31 | if (!h->data) |
32 | { | |
33 | free(h); | |
34 | return NULL; | |
7b0a0eca | 35 | } |
7ac48069 | 36 | memset(h->data, 0, size * sizeof(void *)); |
5eaef520 | 37 | return h; |
b93ad422 | 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 | ||
7ac48069 | 44 | void *hash_lookup(struct hash *h, int key) |
b93ad422 | 45 | { |
44d12d58 | 46 | struct bucket *b; |
5eaef520 | 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; | |
b93ad422 | 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 | ||
7ac48069 | 62 | int hash_update(struct hash *h, int key, void *value) |
b93ad422 | 63 | { |
44d12d58 | 64 | struct bucket *b; |
5eaef520 | 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; | |
b93ad422 | 76 | } |
77 | ||
78 | ||
79 | /* Store an item in the hash table. Returns 0 if the key was not previously | |
7b0a0eca | 80 | * there, 1 if it was, or -1 if we ran out of memory. |
b93ad422 | 81 | */ |
82 | ||
7ac48069 | 83 | int hash_store(struct hash *h, int key, void *value) |
b93ad422 | 84 | { |
44d12d58 | 85 | struct bucket *b, **p; |
5eaef520 | 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; | |
b93ad422 | 97 | } |
98 | ||
5eaef520 | 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; | |
b93ad422 | 105 | } |
5eaef520 | 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; | |
b93ad422 | 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 | ||
7ac48069 | 120 | void hash_search(struct hash *h, void *value, void (*callback)(int)) |
b93ad422 | 121 | { |
44d12d58 | 122 | struct bucket *b, **p; |
5eaef520 | 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); | |
b93ad422 | 130 | } |
131 | } | |
132 | } | |
133 | ||
134 | ||
0efcee1f | 135 | /* Step through the hash table, calling the callback proc with each key. |
136 | */ | |
137 | ||
7ac48069 | 138 | void hash_step(struct hash *h, void (*callback)(int, void *, void *), |
139 | void *hint) | |
0efcee1f | 140 | { |
44d12d58 | 141 | struct bucket *b, **p; |
0efcee1f | 142 | |
5eaef520 | 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); | |
0efcee1f | 147 | } |
148 | } | |
149 | ||
150 | ||
b93ad422 | 151 | /* Deallocate all of the memory associated with a table */ |
152 | ||
7ac48069 | 153 | void hash_destroy(struct hash *h) |
b93ad422 | 154 | { |
44d12d58 | 155 | struct bucket *b, **p, *b1; |
5eaef520 | 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); | |
b93ad422 | 163 | } |
164 | } | |
165 | } |