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b93ad422 | 1 | /* $Header$ |
2 | * | |
3 | * Generic hash table routines. Uses integer keys to store char * values. | |
babbc197 | 4 | * |
5 | * (c) Copyright 1988 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> |
b93ad422 | 11 | #include <ctype.h> |
8defc06b | 12 | #include <moira.h> |
d9e7aa31 | 13 | |
24582af9 | 14 | extern char *malloc(); |
15 | ||
b93ad422 | 16 | #define NULL 0 |
8e24e9aa | 17 | #define hash_func(h, key) (key >= 0 ? (key % h->size) : (-key % h->size)) |
b93ad422 | 18 | |
19 | /* Create a hash table. The size is just a hint, not a maximum. */ | |
20 | ||
21 | struct hash *create_hash(size) | |
22 | int size; | |
23 | { | |
24 | struct hash *h; | |
25 | ||
26 | h = (struct hash *) malloc(sizeof(struct hash)); | |
7b0a0eca | 27 | if (h == (struct hash *) NULL) |
28 | return((struct hash *) NULL); | |
b93ad422 | 29 | h->size = size; |
30 | h->data = (struct bucket **) malloc(size * sizeof(char *)); | |
7b0a0eca | 31 | if (h->data == (struct bucket **) NULL) { |
32 | free(h); | |
33 | return((struct hash *) NULL); | |
34 | } | |
b93ad422 | 35 | bzero(h->data, size * sizeof(char *)); |
36 | return(h); | |
37 | } | |
38 | ||
39 | /* Lookup an object in the hash table. Returns the value associated with | |
40 | * the key, or NULL (thus NULL is not a very good value to store...) | |
41 | */ | |
42 | ||
43 | char *hash_lookup(h, key) | |
44 | struct hash *h; | |
45 | register int key; | |
46 | { | |
47 | register struct bucket *b; | |
48 | ||
8e24e9aa | 49 | b = h->data[hash_func(h, key)]; |
b93ad422 | 50 | while (b && b->key != key) |
51 | b = b->next; | |
52 | if (b && b->key == key) | |
53 | return(b->data); | |
54 | else | |
55 | return(NULL); | |
56 | } | |
57 | ||
58 | ||
59 | /* Update an existing object in the hash table. Returns 1 if the object | |
60 | * existed, or 0 if not. | |
61 | */ | |
62 | ||
63 | int hash_update(h, key, value) | |
64 | struct hash *h; | |
65 | register int key; | |
66 | char *value; | |
67 | { | |
68 | register struct bucket *b; | |
69 | ||
8e24e9aa | 70 | b = h->data[hash_func(h, key)]; |
b93ad422 | 71 | while (b && b->key != key) |
72 | b = b->next; | |
73 | if (b && b->key == key) { | |
74 | b->data = value; | |
75 | return(1); | |
76 | } else | |
77 | return(0); | |
78 | } | |
79 | ||
80 | ||
81 | /* Store an item in the hash table. Returns 0 if the key was not previously | |
7b0a0eca | 82 | * there, 1 if it was, or -1 if we ran out of memory. |
b93ad422 | 83 | */ |
84 | ||
85 | int hash_store(h, key, value) | |
86 | struct hash *h; | |
87 | register int key; | |
88 | char *value; | |
89 | { | |
90 | register struct bucket *b, **p; | |
91 | ||
8e24e9aa | 92 | p = &(h->data[hash_func(h, key)]); |
b93ad422 | 93 | if (*p == NULL) { |
94 | b = *p = (struct bucket *) malloc(sizeof(struct bucket)); | |
7b0a0eca | 95 | if (b == (struct bucket *) NULL) |
96 | return(-1); | |
b93ad422 | 97 | b->next = NULL; |
98 | b->key = key; | |
99 | b->data = value; | |
100 | return(0); | |
101 | } | |
102 | ||
103 | for (b = *p; b && b->key != key; b = *p) | |
104 | p = (struct bucket **) *p; | |
105 | if (b && b->key == key) { | |
106 | b->data = value; | |
107 | return(1); | |
108 | } | |
109 | b = *p = (struct bucket *) malloc(sizeof(struct bucket)); | |
7b0a0eca | 110 | if (b == (struct bucket *) NULL) |
111 | return(-1); | |
b93ad422 | 112 | b->next = NULL; |
113 | b->key = key; | |
114 | b->data = value; | |
115 | return(0); | |
116 | } | |
117 | ||
118 | ||
119 | /* Search through the hash table for a given value. For each piece of | |
120 | * data with that value, call the callback proc with the corresponding key. | |
121 | */ | |
122 | ||
123 | hash_search(h, value, callback) | |
124 | struct hash *h; | |
125 | register char *value; | |
126 | void (*callback)(); | |
127 | { | |
128 | register struct bucket *b, **p; | |
129 | ||
130 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) { | |
131 | for (b = *p; b; b = b->next) { | |
132 | if (b->data == value) | |
133 | (*callback)(b->key); | |
134 | } | |
135 | } | |
136 | } | |
137 | ||
138 | ||
0efcee1f | 139 | /* Step through the hash table, calling the callback proc with each key. |
140 | */ | |
141 | ||
07d9123c | 142 | hash_step(h, callback, hint) |
0efcee1f | 143 | struct hash *h; |
144 | void (*callback)(); | |
07d9123c | 145 | char *hint; |
0efcee1f | 146 | { |
147 | register struct bucket *b, **p; | |
148 | ||
149 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) { | |
150 | for (b = *p; b; b = b->next) { | |
07d9123c | 151 | (*callback)(b->key, b->data, hint); |
0efcee1f | 152 | } |
153 | } | |
154 | } | |
155 | ||
156 | ||
b93ad422 | 157 | /* Deallocate all of the memory associated with a table */ |
158 | ||
159 | hash_destroy(h) | |
160 | struct hash *h; | |
161 | { | |
162 | register struct bucket *b, **p, *b1; | |
163 | ||
164 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) { | |
165 | for (b = *p; b; b = b1) { | |
166 | b1 = b->next; | |
167 | free(b); | |
168 | } | |
169 | } | |
170 | } |