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e2eaf477 ILT |
1 | /* An expandable hash tables datatype. |
2 | Copyright (C) 1999 Free Software Foundation, Inc. | |
3 | Contributed by Vladimir Makarov (vmakarov@cygnus.com). | |
4 | ||
5 | This file is part of the libiberty library. | |
6 | Libiberty is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Library General Public | |
8 | License as published by the Free Software Foundation; either | |
9 | version 2 of the License, or (at your option) any later version. | |
10 | ||
11 | Libiberty is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Library General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Library General Public | |
17 | License along with libiberty; see the file COPYING.LIB. If | |
18 | not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | /* This package implements basic hash table functionality. It is possible | |
22 | to search for an entry, create an entry and destroy an entry. | |
23 | ||
24 | Elements in the table are generic pointers. | |
25 | ||
26 | The size of the table is not fixed; if the occupancy of the table | |
27 | grows too high the hash table will be expanded. | |
28 | ||
29 | The abstract data implementation is based on generalized Algorithm D | |
30 | from Knuth's book "The art of computer programming". Hash table is | |
31 | expanded by creation of new hash table and transferring elements from | |
32 | the old table to the new table. */ | |
33 | ||
34 | #ifdef HAVE_CONFIG_H | |
35 | #include "config.h" | |
36 | #endif | |
37 | ||
38 | #include <sys/types.h> | |
39 | ||
40 | #ifdef HAVE_STDLIB_H | |
41 | #include <stdlib.h> | |
42 | #endif | |
43 | ||
44 | #include <stdio.h> | |
45 | ||
46 | #include "libiberty.h" | |
47 | #include "hashtab.h" | |
48 | ||
e2eaf477 ILT |
49 | /* This macro defines reserved value for empty table entry. */ |
50 | ||
b4fe2683 | 51 | #define EMPTY_ENTRY ((void *) 0) |
e2eaf477 ILT |
52 | |
53 | /* This macro defines reserved value for table entry which contained | |
54 | a deleted element. */ | |
55 | ||
56 | #define DELETED_ENTRY ((void *) 1) | |
57 | ||
58 | /* The following function returns the nearest prime number which is | |
59 | greater than given source number. */ | |
60 | ||
61 | static unsigned long | |
b4fe2683 JM |
62 | higher_prime_number (n) |
63 | unsigned long n; | |
e2eaf477 ILT |
64 | { |
65 | unsigned long i; | |
66 | ||
b4fe2683 JM |
67 | n |= 0x01; /* Force N to be odd. */ |
68 | if (n < 9) | |
69 | return n; /* All odd numbers < 9 are prime. */ | |
70 | ||
71 | next: | |
72 | n += 2; | |
73 | i = 3; | |
74 | do | |
e2eaf477 | 75 | { |
b4fe2683 JM |
76 | if (n % i == 0) |
77 | goto next; | |
78 | i += 2; | |
e2eaf477 | 79 | } |
b4fe2683 JM |
80 | while ((i * i) <= n); |
81 | ||
82 | return n; | |
e2eaf477 ILT |
83 | } |
84 | ||
85 | /* This function creates table with length slightly longer than given | |
86 | source length. Created hash table is initiated as empty (all the | |
87 | hash table entries are EMPTY_ENTRY). The function returns the | |
88 | created hash table. */ | |
89 | ||
b4fe2683 JM |
90 | htab_t |
91 | htab_create (size, hash_f, eq_f, del_f) | |
e2eaf477 | 92 | size_t size; |
b4fe2683 JM |
93 | htab_hash hash_f; |
94 | htab_eq eq_f; | |
95 | htab_del del_f; | |
e2eaf477 | 96 | { |
b4fe2683 | 97 | htab_t result; |
e2eaf477 ILT |
98 | |
99 | size = higher_prime_number (size); | |
b4fe2683 JM |
100 | result = (htab_t) xcalloc (1, sizeof (struct htab)); |
101 | result->entries = (void **) xcalloc (size, sizeof (void *)); | |
e2eaf477 | 102 | result->size = size; |
b4fe2683 JM |
103 | result->hash_f = hash_f; |
104 | result->eq_f = eq_f; | |
105 | result->del_f = del_f; | |
e2eaf477 ILT |
106 | return result; |
107 | } | |
108 | ||
109 | /* This function frees all memory allocated for given hash table. | |
110 | Naturally the hash table must already exist. */ | |
111 | ||
112 | void | |
b4fe2683 JM |
113 | htab_delete (htab) |
114 | htab_t htab; | |
e2eaf477 | 115 | { |
b4fe2683 JM |
116 | int i; |
117 | if (htab->del_f) | |
118 | for (i = htab->size - 1; i >= 0; i--) | |
119 | { | |
120 | if (htab->entries[i] != EMPTY_ENTRY | |
121 | && htab->entries[i] != DELETED_ENTRY) | |
122 | (*htab->del_f) (htab->entries[i]); | |
123 | } | |
124 | ||
e2eaf477 ILT |
125 | free (htab->entries); |
126 | free (htab); | |
127 | } | |
128 | ||
129 | /* This function clears all entries in the given hash table. */ | |
130 | ||
131 | void | |
b4fe2683 JM |
132 | htab_empty (htab) |
133 | htab_t htab; | |
134 | { | |
135 | int i; | |
136 | if (htab->del_f) | |
137 | for (i = htab->size - 1; i >= 0; i--) | |
138 | { | |
139 | if (htab->entries[i] != EMPTY_ENTRY | |
140 | && htab->entries[i] != DELETED_ENTRY) | |
141 | (*htab->del_f) (htab->entries[i]); | |
142 | } | |
143 | ||
144 | memset (htab->entries, 0, htab->size * sizeof (void *)); | |
145 | } | |
146 | ||
147 | /* Similar to htab_find_slot, but without several unwanted side effects: | |
148 | - Does not call htab->eq_f when it finds an existing entry. | |
149 | - Does not change the count of elements/searches/collisions in the | |
150 | hash table. | |
151 | This function also assumes there are no deleted entries in the table. | |
152 | HASH is the hash value for the element to be inserted. */ | |
153 | static void ** | |
154 | find_empty_slot_for_expand (htab, hash) | |
155 | htab_t htab; | |
156 | unsigned int hash; | |
e2eaf477 | 157 | { |
b4fe2683 JM |
158 | size_t size = htab->size; |
159 | unsigned int hash2 = 1 + hash % (size - 2); | |
160 | unsigned int index = hash % size; | |
161 | ||
162 | for (;;) | |
163 | { | |
164 | void **slot = htab->entries + index; | |
165 | if (*slot == EMPTY_ENTRY) | |
166 | return slot; | |
167 | ||
168 | if (*slot == DELETED_ENTRY) | |
169 | abort (); | |
170 | ||
171 | index += hash2; | |
172 | if (index >= size) | |
173 | index -= size; | |
174 | } | |
e2eaf477 ILT |
175 | } |
176 | ||
177 | /* The following function changes size of memory allocated for the | |
178 | entries and repeatedly inserts the table elements. The occupancy | |
179 | of the table after the call will be about 50%. Naturally the hash | |
180 | table must already exist. Remember also that the place of the | |
181 | table entries is changed. */ | |
182 | ||
183 | static void | |
b4fe2683 JM |
184 | htab_expand (htab) |
185 | htab_t htab; | |
e2eaf477 | 186 | { |
b4fe2683 JM |
187 | void **oentries; |
188 | void **olimit; | |
189 | void **p; | |
190 | ||
191 | oentries = htab->entries; | |
192 | olimit = oentries + htab->size; | |
193 | ||
194 | htab->size = higher_prime_number (htab->size * 2); | |
195 | htab->entries = xcalloc (htab->size, sizeof (void **)); | |
196 | ||
197 | htab->n_elements -= htab->n_deleted; | |
198 | htab->n_deleted = 0; | |
199 | ||
200 | p = oentries; | |
201 | do | |
202 | { | |
203 | void *x = *p; | |
204 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) | |
205 | { | |
206 | void **q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x)); | |
207 | *q = x; | |
208 | } | |
209 | p++; | |
210 | } | |
211 | while (p < olimit); | |
212 | free (oentries); | |
e2eaf477 ILT |
213 | } |
214 | ||
b4fe2683 JM |
215 | /* This function searches for a hash table entry equal to the given |
216 | element. It cannot be used to insert or delete an element. */ | |
217 | ||
218 | void * | |
219 | htab_find_with_hash (htab, element, hash) | |
220 | htab_t htab; | |
221 | const void *element; | |
222 | unsigned int hash; | |
e2eaf477 | 223 | { |
b4fe2683 JM |
224 | unsigned int index, hash2; |
225 | size_t size; | |
e2eaf477 | 226 | |
b4fe2683 JM |
227 | htab->searches++; |
228 | size = htab->size; | |
229 | hash2 = 1 + hash % (size - 2); | |
230 | index = hash % size; | |
231 | ||
232 | for (;;) | |
e2eaf477 | 233 | { |
b4fe2683 JM |
234 | void *entry = htab->entries[index]; |
235 | if (entry == EMPTY_ENTRY) | |
236 | return NULL; | |
237 | else if (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element)) | |
238 | return entry; | |
239 | ||
240 | htab->collisions++; | |
241 | index += hash2; | |
242 | if (index >= size) | |
243 | index -= size; | |
e2eaf477 | 244 | } |
b4fe2683 JM |
245 | } |
246 | ||
247 | /* Like htab_find_slot_with_hash, but compute the hash value from the | |
248 | element. */ | |
249 | void * | |
250 | htab_find (htab, element) | |
251 | htab_t htab; | |
252 | const void *element; | |
253 | { | |
254 | return htab_find_with_hash (htab, element, (*htab->hash_f) (element)); | |
255 | } | |
256 | ||
257 | /* This function searches for a hash table slot containing an entry | |
258 | equal to the given element. To delete an entry, call this with | |
259 | INSERT = 0, then call htab_clear_slot on the slot returned (possibly | |
260 | after doing some checks). To insert an entry, call this with | |
261 | INSERT = 1, then write the value you want into the returned slot. */ | |
262 | ||
263 | void ** | |
264 | htab_find_slot_with_hash (htab, element, hash, insert) | |
265 | htab_t htab; | |
266 | const void *element; | |
267 | unsigned int hash; | |
268 | int insert; | |
269 | { | |
270 | void **first_deleted_slot; | |
271 | unsigned int index, hash2; | |
272 | size_t size; | |
273 | ||
274 | if (insert && htab->size * 3 <= htab->n_elements * 4) | |
275 | htab_expand (htab); | |
276 | ||
277 | size = htab->size; | |
278 | hash2 = 1 + hash % (size - 2); | |
279 | index = hash % size; | |
280 | ||
e2eaf477 | 281 | htab->searches++; |
b4fe2683 JM |
282 | first_deleted_slot = NULL; |
283 | ||
284 | for (;;) | |
e2eaf477 | 285 | { |
b4fe2683 JM |
286 | void *entry = htab->entries[index]; |
287 | if (entry == EMPTY_ENTRY) | |
288 | { | |
289 | if (!insert) | |
290 | return NULL; | |
291 | ||
292 | htab->n_elements++; | |
293 | ||
294 | if (first_deleted_slot) | |
e2eaf477 | 295 | { |
b4fe2683 JM |
296 | *first_deleted_slot = EMPTY_ENTRY; |
297 | return first_deleted_slot; | |
e2eaf477 | 298 | } |
b4fe2683 JM |
299 | |
300 | return &htab->entries[index]; | |
301 | } | |
302 | ||
303 | if (entry == DELETED_ENTRY) | |
304 | { | |
305 | if (!first_deleted_slot) | |
306 | first_deleted_slot = &htab->entries[index]; | |
307 | } | |
308 | else | |
309 | { | |
310 | if ((*htab->eq_f) (entry, element)) | |
311 | return &htab->entries[index]; | |
312 | } | |
313 | ||
314 | htab->collisions++; | |
315 | index += hash2; | |
316 | if (index >= size) | |
317 | index -= size; | |
e2eaf477 | 318 | } |
e2eaf477 ILT |
319 | } |
320 | ||
b4fe2683 JM |
321 | /* Like htab_find_slot_with_hash, but compute the hash value from the |
322 | element. */ | |
323 | void ** | |
324 | htab_find_slot (htab, element, insert) | |
325 | htab_t htab; | |
326 | const void *element; | |
327 | int insert; | |
328 | { | |
329 | return htab_find_slot_with_hash (htab, element, (*htab->hash_f) (element), | |
330 | insert); | |
331 | } | |
332 | ||
333 | /* This function deletes an element with the given value from hash | |
334 | table. If there is no matching element in the hash table, this | |
335 | function does nothing. */ | |
e2eaf477 ILT |
336 | |
337 | void | |
b4fe2683 JM |
338 | htab_remove_elt (htab, element) |
339 | htab_t htab; | |
340 | void *element; | |
e2eaf477 | 341 | { |
b4fe2683 JM |
342 | void **slot; |
343 | ||
344 | slot = htab_find_slot (htab, element, 0); | |
345 | if (*slot == EMPTY_ENTRY) | |
346 | return; | |
347 | ||
348 | if (htab->del_f) | |
349 | (*htab->del_f) (*slot); | |
e2eaf477 | 350 | |
b4fe2683 JM |
351 | *slot = DELETED_ENTRY; |
352 | htab->n_deleted++; | |
e2eaf477 ILT |
353 | } |
354 | ||
b4fe2683 JM |
355 | /* This function clears a specified slot in a hash table. It is |
356 | useful when you've already done the lookup and don't want to do it | |
357 | again. */ | |
e2eaf477 ILT |
358 | |
359 | void | |
b4fe2683 JM |
360 | htab_clear_slot (htab, slot) |
361 | htab_t htab; | |
362 | void **slot; | |
e2eaf477 ILT |
363 | { |
364 | if (slot < htab->entries || slot >= htab->entries + htab->size | |
365 | || *slot == EMPTY_ENTRY || *slot == DELETED_ENTRY) | |
366 | abort (); | |
b4fe2683 JM |
367 | if (htab->del_f) |
368 | (*htab->del_f) (*slot); | |
e2eaf477 | 369 | *slot = DELETED_ENTRY; |
b4fe2683 | 370 | htab->n_deleted++; |
e2eaf477 ILT |
371 | } |
372 | ||
373 | /* This function scans over the entire hash table calling | |
374 | CALLBACK for each live entry. If CALLBACK returns false, | |
375 | the iteration stops. INFO is passed as CALLBACK's second | |
376 | argument. */ | |
377 | ||
378 | void | |
b4fe2683 JM |
379 | htab_traverse (htab, callback, info) |
380 | htab_t htab; | |
381 | htab_trav callback; | |
e2eaf477 ILT |
382 | void *info; |
383 | { | |
b4fe2683 JM |
384 | void **slot, **limit; |
385 | slot = htab->entries; | |
386 | limit = slot + htab->size; | |
387 | do | |
388 | { | |
389 | void *x = *slot; | |
390 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) | |
391 | if (!(*callback) (slot, info)) | |
392 | break; | |
393 | } | |
394 | while (++slot < limit); | |
e2eaf477 ILT |
395 | } |
396 | ||
397 | /* The following function returns current size of given hash table. */ | |
398 | ||
399 | size_t | |
b4fe2683 JM |
400 | htab_size (htab) |
401 | htab_t htab; | |
e2eaf477 ILT |
402 | { |
403 | return htab->size; | |
404 | } | |
405 | ||
406 | /* The following function returns current number of elements in given | |
407 | hash table. */ | |
408 | ||
409 | size_t | |
b4fe2683 JM |
410 | htab_elements (htab) |
411 | htab_t htab; | |
e2eaf477 | 412 | { |
b4fe2683 | 413 | return htab->n_elements - htab->n_deleted; |
e2eaf477 ILT |
414 | } |
415 | ||
416 | /* The following function returns number of percents of fixed | |
417 | collisions during all work with given hash table. */ | |
418 | ||
b4fe2683 JM |
419 | double |
420 | htab_collisions (htab) | |
421 | htab_t htab; | |
e2eaf477 ILT |
422 | { |
423 | int searches; | |
424 | ||
425 | searches = htab->searches; | |
426 | if (searches == 0) | |
b4fe2683 JM |
427 | return 0.0; |
428 | return (double)htab->collisions / (double)searches; | |
e2eaf477 | 429 | } |