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88e17b57 | 1 | /* Hash tables for Objective C internal structures |
435317e2 | 2 | Copyright (C) 1993, 1996, 1997, 2004 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 BE |
7 | it under the terms of the GNU General Public License as published by |
8 | the Free Software Foundation; either version 2, or (at your option) | |
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 | ||
16 | You should have received a copy of the GNU General Public License | |
38709cad | 17 | along with GCC; see the file COPYING. If not, write to |
88e17b57 BE |
18 | the Free Software Foundation, 59 Temple Place - Suite 330, |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | /* As a special exception, if you link this library with files | |
22 | compiled with GCC to produce an executable, this does not cause | |
23 | the resulting executable to be covered by the GNU General Public License. | |
24 | This exception does not however invalidate any other reasons why | |
25 | the executable file might be covered by the GNU General Public License. */ | |
26 | ||
27 | #include "assert.h" | |
28 | ||
bce1b489 | 29 | #include "hash.h" |
88e17b57 BE |
30 | |
31 | #include "runtime.h" /* for DEBUG_PRINTF */ | |
32 | ||
33 | /* These two macros determine when a hash table is full and | |
34 | by how much it should be expanded respectively. | |
35 | ||
36 | These equations are percentages. */ | |
37 | #define FULLNESS(cache) \ | |
38 | ((((cache)->size * 75) / 100) <= (cache)->used) | |
39 | #define EXPANSION(cache) \ | |
40 | ((cache)->size * 2) | |
41 | ||
42 | cache_ptr | |
43 | hash_new (unsigned int size, hash_func_type hash_func, | |
44 | compare_func_type compare_func) | |
45 | { | |
46 | cache_ptr cache; | |
47 | ||
48 | /* Pass me a value greater than 0 and a power of 2. */ | |
49 | assert (size); | |
40165636 | 50 | assert (! (size & (size - 1))); |
88e17b57 BE |
51 | |
52 | /* Allocate the cache structure. calloc insures | |
53 | its initialization for default values. */ | |
54 | cache = (cache_ptr) objc_calloc (1, sizeof (struct cache)); | |
55 | assert (cache); | |
56 | ||
57 | /* Allocate the array of buckets for the cache. | |
58 | calloc initializes all of the pointers to NULL. */ | |
59 | cache->node_table | |
60 | = (node_ptr *) objc_calloc (size, sizeof (node_ptr)); | |
61 | assert (cache->node_table); | |
62 | ||
63 | cache->size = size; | |
64 | ||
65 | /* This should work for all processor architectures? */ | |
66 | cache->mask = (size - 1); | |
67 | ||
68 | /* Store the hashing function so that codes can be computed. */ | |
69 | cache->hash_func = hash_func; | |
70 | ||
71 | /* Store the function that compares hash keys to | |
72 | determine if they are equal. */ | |
73 | cache->compare_func = compare_func; | |
74 | ||
75 | return cache; | |
76 | } | |
77 | ||
78 | ||
79 | void | |
80 | hash_delete (cache_ptr cache) | |
81 | { | |
82 | node_ptr node; | |
83 | node_ptr next_node; | |
84 | unsigned int i; | |
85 | ||
86 | /* Purge all key/value pairs from the table. */ | |
87 | /* Step through the nodes one by one and remove every node WITHOUT | |
88 | using hash_next. this makes hash_delete much more efficient. */ | |
89 | for (i = 0;i < cache->size;i++) { | |
90 | if ((node = cache->node_table[i])) { | |
91 | /* an entry in the hash table has been found, now step through the | |
92 | nodes next in the list and free them. */ | |
93 | while ((next_node = node->next)) { | |
94 | hash_remove (cache,node->key); | |
95 | node = next_node; | |
96 | } | |
97 | ||
98 | hash_remove (cache,node->key); | |
99 | } | |
100 | } | |
101 | ||
102 | /* Release the array of nodes and the cache itself. */ | |
103 | objc_free(cache->node_table); | |
104 | objc_free(cache); | |
105 | } | |
106 | ||
107 | ||
108 | void | |
109 | hash_add (cache_ptr *cachep, const void *key, void *value) | |
110 | { | |
111 | size_t indx = (*(*cachep)->hash_func)(*cachep, key); | |
112 | node_ptr node = (node_ptr) objc_calloc (1, sizeof (struct cache_node)); | |
113 | ||
114 | ||
115 | assert (node); | |
116 | ||
117 | /* Initialize the new node. */ | |
118 | node->key = key; | |
119 | node->value = value; | |
120 | node->next = (*cachep)->node_table[indx]; | |
121 | ||
122 | /* Debugging. | |
123 | Check the list for another key. */ | |
124 | #ifdef DEBUG | |
125 | { node_ptr node1 = (*cachep)->node_table[indx]; | |
126 | ||
127 | while (node1) { | |
128 | ||
129 | assert (node1->key != key); | |
130 | node1 = node1->next; | |
131 | } | |
132 | } | |
133 | #endif | |
134 | ||
135 | /* Install the node as the first element on the list. */ | |
136 | (*cachep)->node_table[indx] = node; | |
137 | ||
138 | /* Bump the number of entries in the cache. */ | |
139 | ++(*cachep)->used; | |
140 | ||
141 | /* Check the hash table's fullness. We're going | |
142 | to expand if it is above the fullness level. */ | |
143 | if (FULLNESS (*cachep)) { | |
144 | ||
145 | /* The hash table has reached its fullness level. Time to | |
146 | expand it. | |
147 | ||
148 | I'm using a slow method here but is built on other | |
149 | primitive functions thereby increasing its | |
150 | correctness. */ | |
151 | node_ptr node1 = NULL; | |
152 | cache_ptr new = hash_new (EXPANSION (*cachep), | |
153 | (*cachep)->hash_func, | |
154 | (*cachep)->compare_func); | |
155 | ||
156 | DEBUG_PRINTF ("Expanding cache %#x from %d to %d\n", | |
435317e2 | 157 | (int) *cachep, (*cachep)->size, new->size); |
88e17b57 BE |
158 | |
159 | /* Copy the nodes from the first hash table to the new one. */ | |
160 | while ((node1 = hash_next (*cachep, node1))) | |
161 | hash_add (&new, node1->key, node1->value); | |
162 | ||
163 | /* Trash the old cache. */ | |
164 | hash_delete (*cachep); | |
165 | ||
166 | /* Return a pointer to the new hash table. */ | |
167 | *cachep = new; | |
168 | } | |
169 | } | |
170 | ||
171 | ||
172 | void | |
173 | hash_remove (cache_ptr cache, const void *key) | |
174 | { | |
175 | size_t indx = (*cache->hash_func)(cache, key); | |
176 | node_ptr node = cache->node_table[indx]; | |
177 | ||
178 | ||
179 | /* We assume there is an entry in the table. Error if it is not. */ | |
180 | assert (node); | |
181 | ||
182 | /* Special case. First element is the key/value pair to be removed. */ | |
183 | if ((*cache->compare_func)(node->key, key)) { | |
184 | cache->node_table[indx] = node->next; | |
185 | objc_free(node); | |
186 | } else { | |
187 | ||
188 | /* Otherwise, find the hash entry. */ | |
189 | node_ptr prev = node; | |
190 | BOOL removed = NO; | |
191 | ||
192 | do { | |
193 | ||
194 | if ((*cache->compare_func)(node->key, key)) { | |
195 | prev->next = node->next, removed = YES; | |
196 | objc_free(node); | |
197 | } else | |
198 | prev = node, node = node->next; | |
40165636 | 199 | } while (! removed && node); |
88e17b57 BE |
200 | assert (removed); |
201 | } | |
202 | ||
203 | /* Decrement the number of entries in the hash table. */ | |
204 | --cache->used; | |
205 | } | |
206 | ||
207 | ||
208 | node_ptr | |
209 | hash_next (cache_ptr cache, node_ptr node) | |
210 | { | |
211 | /* If the scan is being started then reset the last node | |
212 | visitied pointer and bucket index. */ | |
40165636 | 213 | if (! node) |
88e17b57 BE |
214 | cache->last_bucket = 0; |
215 | ||
216 | /* If there is a node visited last then check for another | |
217 | entry in the same bucket; Otherwise step to the next bucket. */ | |
218 | if (node) { | |
219 | if (node->next) | |
220 | /* There is a node which follows the last node | |
221 | returned. Step to that node and retun it. */ | |
222 | return node->next; | |
223 | else | |
224 | ++cache->last_bucket; | |
225 | } | |
226 | ||
227 | /* If the list isn't exhausted then search the buckets for | |
228 | other nodes. */ | |
229 | if (cache->last_bucket < cache->size) { | |
230 | /* Scan the remainder of the buckets looking for an entry | |
231 | at the head of the list. Return the first item found. */ | |
232 | while (cache->last_bucket < cache->size) | |
233 | if (cache->node_table[cache->last_bucket]) | |
234 | return cache->node_table[cache->last_bucket]; | |
235 | else | |
236 | ++cache->last_bucket; | |
237 | ||
238 | /* No further nodes were found in the hash table. */ | |
239 | return NULL; | |
240 | } else | |
241 | return NULL; | |
242 | } | |
243 | ||
244 | ||
245 | /* Given KEY, return corresponding value for it in CACHE. | |
246 | Return NULL if the KEY is not recorded. */ | |
247 | ||
248 | void * | |
249 | hash_value_for_key (cache_ptr cache, const void *key) | |
250 | { | |
251 | node_ptr node = cache->node_table[(*cache->hash_func)(cache, key)]; | |
252 | void *retval = NULL; | |
253 | ||
254 | if (node) | |
255 | do { | |
256 | if ((*cache->compare_func)(node->key, key)) { | |
257 | retval = node->value; | |
258 | break; | |
259 | } else | |
260 | node = node->next; | |
40165636 | 261 | } while (! retval && node); |
88e17b57 BE |
262 | |
263 | return retval; | |
264 | } | |
265 | ||
266 | /* Given KEY, return YES if it exists in the CACHE. | |
267 | Return NO if it does not */ | |
268 | ||
269 | BOOL | |
270 | hash_is_key_in_hash (cache_ptr cache, const void *key) | |
271 | { | |
272 | node_ptr node = cache->node_table[(*cache->hash_func)(cache, key)]; | |
273 | ||
274 | if (node) | |
275 | do { | |
276 | if ((*cache->compare_func)(node->key, key)) | |
277 | return YES; | |
278 | else | |
279 | node = node->next; | |
280 | } while (node); | |
281 | ||
282 | return NO; | |
283 | } |