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88e17b57 | 1 | /* Hash tables for Objective C internal structures |
748086b7 | 2 | Copyright (C) 1993, 1996, 1997, 2004, 2009 Free Software Foundation, Inc. |
88e17b57 | 3 | |
38709cad | 4 | This file is part of GCC. |
88e17b57 | 5 | |
38709cad | 6 | GCC is free software; you can redistribute it and/or modify |
88e17b57 | 7 | it under the terms of the GNU General Public License as published by |
748086b7 | 8 | the Free Software Foundation; either version 3, or (at your option) |
88e17b57 BE |
9 | any later version. |
10 | ||
38709cad | 11 | GCC is distributed in the hope that it will be useful, |
88e17b57 BE |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
748086b7 JJ |
16 | Under Section 7 of GPL version 3, you are granted additional |
17 | permissions described in the GCC Runtime Library Exception, version | |
18 | 3.1, as published by the Free Software Foundation. | |
88e17b57 | 19 | |
748086b7 JJ |
20 | You should have received a copy of the GNU General Public License and |
21 | a copy of the GCC Runtime Library Exception along with this program; | |
22 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | <http://www.gnu.org/licenses/>. */ | |
88e17b57 BE |
24 | |
25 | #include "assert.h" | |
26 | ||
348a3445 | 27 | #include "objc/hash.h" |
88e17b57 | 28 | |
348a3445 | 29 | #include "objc/runtime.h" /* for DEBUG_PRINTF */ |
88e17b57 BE |
30 | |
31 | /* These two macros determine when a hash table is full and | |
32 | by how much it should be expanded respectively. | |
33 | ||
34 | These equations are percentages. */ | |
35 | #define FULLNESS(cache) \ | |
36 | ((((cache)->size * 75) / 100) <= (cache)->used) | |
37 | #define EXPANSION(cache) \ | |
38 | ((cache)->size * 2) | |
39 | ||
40 | cache_ptr | |
270a1283 DA |
41 | objc_hash_new (unsigned int size, hash_func_type hash_func, |
42 | compare_func_type compare_func) | |
88e17b57 BE |
43 | { |
44 | cache_ptr cache; | |
45 | ||
46 | /* Pass me a value greater than 0 and a power of 2. */ | |
47 | assert (size); | |
40165636 | 48 | assert (! (size & (size - 1))); |
88e17b57 BE |
49 | |
50 | /* Allocate the cache structure. calloc insures | |
51 | its initialization for default values. */ | |
52 | cache = (cache_ptr) objc_calloc (1, sizeof (struct cache)); | |
53 | assert (cache); | |
54 | ||
55 | /* Allocate the array of buckets for the cache. | |
56 | calloc initializes all of the pointers to NULL. */ | |
57 | cache->node_table | |
58 | = (node_ptr *) objc_calloc (size, sizeof (node_ptr)); | |
59 | assert (cache->node_table); | |
60 | ||
61 | cache->size = size; | |
62 | ||
63 | /* This should work for all processor architectures? */ | |
64 | cache->mask = (size - 1); | |
65 | ||
66 | /* Store the hashing function so that codes can be computed. */ | |
67 | cache->hash_func = hash_func; | |
68 | ||
69 | /* Store the function that compares hash keys to | |
70 | determine if they are equal. */ | |
71 | cache->compare_func = compare_func; | |
72 | ||
73 | return cache; | |
74 | } | |
75 | ||
76 | ||
77 | void | |
270a1283 | 78 | objc_hash_delete (cache_ptr cache) |
88e17b57 BE |
79 | { |
80 | node_ptr node; | |
81 | node_ptr next_node; | |
82 | unsigned int i; | |
83 | ||
84 | /* Purge all key/value pairs from the table. */ | |
85 | /* Step through the nodes one by one and remove every node WITHOUT | |
270a1283 | 86 | using objc_hash_next. this makes objc_hash_delete much more efficient. */ |
88e17b57 BE |
87 | for (i = 0;i < cache->size;i++) { |
88 | if ((node = cache->node_table[i])) { | |
89 | /* an entry in the hash table has been found, now step through the | |
90 | nodes next in the list and free them. */ | |
91 | while ((next_node = node->next)) { | |
270a1283 | 92 | objc_hash_remove (cache,node->key); |
88e17b57 BE |
93 | node = next_node; |
94 | } | |
95 | ||
270a1283 | 96 | objc_hash_remove (cache,node->key); |
88e17b57 BE |
97 | } |
98 | } | |
99 | ||
100 | /* Release the array of nodes and the cache itself. */ | |
101 | objc_free(cache->node_table); | |
102 | objc_free(cache); | |
103 | } | |
104 | ||
105 | ||
106 | void | |
270a1283 | 107 | objc_hash_add (cache_ptr *cachep, const void *key, void *value) |
88e17b57 BE |
108 | { |
109 | size_t indx = (*(*cachep)->hash_func)(*cachep, key); | |
110 | node_ptr node = (node_ptr) objc_calloc (1, sizeof (struct cache_node)); | |
111 | ||
112 | ||
113 | assert (node); | |
114 | ||
115 | /* Initialize the new node. */ | |
116 | node->key = key; | |
117 | node->value = value; | |
118 | node->next = (*cachep)->node_table[indx]; | |
119 | ||
120 | /* Debugging. | |
121 | Check the list for another key. */ | |
122 | #ifdef DEBUG | |
123 | { node_ptr node1 = (*cachep)->node_table[indx]; | |
124 | ||
125 | while (node1) { | |
126 | ||
127 | assert (node1->key != key); | |
128 | node1 = node1->next; | |
129 | } | |
130 | } | |
131 | #endif | |
132 | ||
133 | /* Install the node as the first element on the list. */ | |
134 | (*cachep)->node_table[indx] = node; | |
135 | ||
136 | /* Bump the number of entries in the cache. */ | |
137 | ++(*cachep)->used; | |
138 | ||
139 | /* Check the hash table's fullness. We're going | |
140 | to expand if it is above the fullness level. */ | |
141 | if (FULLNESS (*cachep)) { | |
142 | ||
143 | /* The hash table has reached its fullness level. Time to | |
144 | expand it. | |
145 | ||
146 | I'm using a slow method here but is built on other | |
147 | primitive functions thereby increasing its | |
148 | correctness. */ | |
149 | node_ptr node1 = NULL; | |
270a1283 DA |
150 | cache_ptr new = objc_hash_new (EXPANSION (*cachep), |
151 | (*cachep)->hash_func, | |
152 | (*cachep)->compare_func); | |
88e17b57 BE |
153 | |
154 | DEBUG_PRINTF ("Expanding cache %#x from %d to %d\n", | |
435317e2 | 155 | (int) *cachep, (*cachep)->size, new->size); |
88e17b57 BE |
156 | |
157 | /* Copy the nodes from the first hash table to the new one. */ | |
270a1283 DA |
158 | while ((node1 = objc_hash_next (*cachep, node1))) |
159 | objc_hash_add (&new, node1->key, node1->value); | |
88e17b57 BE |
160 | |
161 | /* Trash the old cache. */ | |
270a1283 | 162 | objc_hash_delete (*cachep); |
88e17b57 BE |
163 | |
164 | /* Return a pointer to the new hash table. */ | |
165 | *cachep = new; | |
166 | } | |
167 | } | |
168 | ||
169 | ||
170 | void | |
270a1283 | 171 | objc_hash_remove (cache_ptr cache, const void *key) |
88e17b57 BE |
172 | { |
173 | size_t indx = (*cache->hash_func)(cache, key); | |
174 | node_ptr node = cache->node_table[indx]; | |
175 | ||
176 | ||
177 | /* We assume there is an entry in the table. Error if it is not. */ | |
178 | assert (node); | |
179 | ||
180 | /* Special case. First element is the key/value pair to be removed. */ | |
181 | if ((*cache->compare_func)(node->key, key)) { | |
182 | cache->node_table[indx] = node->next; | |
183 | objc_free(node); | |
184 | } else { | |
185 | ||
186 | /* Otherwise, find the hash entry. */ | |
187 | node_ptr prev = node; | |
188 | BOOL removed = NO; | |
189 | ||
190 | do { | |
191 | ||
192 | if ((*cache->compare_func)(node->key, key)) { | |
193 | prev->next = node->next, removed = YES; | |
194 | objc_free(node); | |
195 | } else | |
196 | prev = node, node = node->next; | |
40165636 | 197 | } while (! removed && node); |
88e17b57 BE |
198 | assert (removed); |
199 | } | |
200 | ||
201 | /* Decrement the number of entries in the hash table. */ | |
202 | --cache->used; | |
203 | } | |
204 | ||
205 | ||
206 | node_ptr | |
270a1283 | 207 | objc_hash_next (cache_ptr cache, node_ptr node) |
88e17b57 BE |
208 | { |
209 | /* If the scan is being started then reset the last node | |
210 | visitied pointer and bucket index. */ | |
40165636 | 211 | if (! node) |
88e17b57 BE |
212 | cache->last_bucket = 0; |
213 | ||
214 | /* If there is a node visited last then check for another | |
215 | entry in the same bucket; Otherwise step to the next bucket. */ | |
216 | if (node) { | |
217 | if (node->next) | |
218 | /* There is a node which follows the last node | |
219 | returned. Step to that node and retun it. */ | |
220 | return node->next; | |
221 | else | |
222 | ++cache->last_bucket; | |
223 | } | |
224 | ||
225 | /* If the list isn't exhausted then search the buckets for | |
226 | other nodes. */ | |
227 | if (cache->last_bucket < cache->size) { | |
228 | /* Scan the remainder of the buckets looking for an entry | |
229 | at the head of the list. Return the first item found. */ | |
230 | while (cache->last_bucket < cache->size) | |
231 | if (cache->node_table[cache->last_bucket]) | |
232 | return cache->node_table[cache->last_bucket]; | |
233 | else | |
234 | ++cache->last_bucket; | |
235 | ||
236 | /* No further nodes were found in the hash table. */ | |
237 | return NULL; | |
238 | } else | |
239 | return NULL; | |
240 | } | |
241 | ||
242 | ||
243 | /* Given KEY, return corresponding value for it in CACHE. | |
244 | Return NULL if the KEY is not recorded. */ | |
245 | ||
246 | void * | |
270a1283 | 247 | objc_hash_value_for_key (cache_ptr cache, const void *key) |
88e17b57 BE |
248 | { |
249 | node_ptr node = cache->node_table[(*cache->hash_func)(cache, key)]; | |
250 | void *retval = NULL; | |
251 | ||
252 | if (node) | |
253 | do { | |
254 | if ((*cache->compare_func)(node->key, key)) { | |
255 | retval = node->value; | |
256 | break; | |
257 | } else | |
258 | node = node->next; | |
40165636 | 259 | } while (! retval && node); |
88e17b57 BE |
260 | |
261 | return retval; | |
262 | } | |
263 | ||
264 | /* Given KEY, return YES if it exists in the CACHE. | |
265 | Return NO if it does not */ | |
266 | ||
267 | BOOL | |
270a1283 | 268 | objc_hash_is_key_in_hash (cache_ptr cache, const void *key) |
88e17b57 BE |
269 | { |
270 | node_ptr node = cache->node_table[(*cache->hash_func)(cache, key)]; | |
271 | ||
272 | if (node) | |
273 | do { | |
274 | if ((*cache->compare_func)(node->key, key)) | |
275 | return YES; | |
276 | else | |
277 | node = node->next; | |
278 | } while (node); | |
279 | ||
280 | return NO; | |
281 | } |