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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 | ||
5c82d20a ZW |
44 | #ifdef HAVE_STRING_H |
45 | #include <string.h> | |
46 | #endif | |
47 | ||
e2eaf477 ILT |
48 | #include <stdio.h> |
49 | ||
50 | #include "libiberty.h" | |
51 | #include "hashtab.h" | |
52 | ||
e2eaf477 ILT |
53 | /* This macro defines reserved value for empty table entry. */ |
54 | ||
b4fe2683 | 55 | #define EMPTY_ENTRY ((void *) 0) |
e2eaf477 ILT |
56 | |
57 | /* This macro defines reserved value for table entry which contained | |
58 | a deleted element. */ | |
59 | ||
60 | #define DELETED_ENTRY ((void *) 1) | |
61 | ||
62 | /* The following function returns the nearest prime number which is | |
63 | greater than given source number. */ | |
64 | ||
65 | static unsigned long | |
b4fe2683 JM |
66 | higher_prime_number (n) |
67 | unsigned long n; | |
e2eaf477 ILT |
68 | { |
69 | unsigned long i; | |
70 | ||
b4fe2683 JM |
71 | n |= 0x01; /* Force N to be odd. */ |
72 | if (n < 9) | |
73 | return n; /* All odd numbers < 9 are prime. */ | |
74 | ||
75 | next: | |
76 | n += 2; | |
77 | i = 3; | |
78 | do | |
e2eaf477 | 79 | { |
b4fe2683 JM |
80 | if (n % i == 0) |
81 | goto next; | |
82 | i += 2; | |
e2eaf477 | 83 | } |
b4fe2683 JM |
84 | while ((i * i) <= n); |
85 | ||
86 | return n; | |
e2eaf477 ILT |
87 | } |
88 | ||
89 | /* This function creates table with length slightly longer than given | |
90 | source length. Created hash table is initiated as empty (all the | |
91 | hash table entries are EMPTY_ENTRY). The function returns the | |
92 | created hash table. */ | |
93 | ||
b4fe2683 JM |
94 | htab_t |
95 | htab_create (size, hash_f, eq_f, del_f) | |
e2eaf477 | 96 | size_t size; |
b4fe2683 JM |
97 | htab_hash hash_f; |
98 | htab_eq eq_f; | |
99 | htab_del del_f; | |
e2eaf477 | 100 | { |
b4fe2683 | 101 | htab_t result; |
e2eaf477 ILT |
102 | |
103 | size = higher_prime_number (size); | |
b4fe2683 JM |
104 | result = (htab_t) xcalloc (1, sizeof (struct htab)); |
105 | result->entries = (void **) xcalloc (size, sizeof (void *)); | |
e2eaf477 | 106 | result->size = size; |
b4fe2683 JM |
107 | result->hash_f = hash_f; |
108 | result->eq_f = eq_f; | |
109 | result->del_f = del_f; | |
e2eaf477 ILT |
110 | return result; |
111 | } | |
112 | ||
113 | /* This function frees all memory allocated for given hash table. | |
114 | Naturally the hash table must already exist. */ | |
115 | ||
116 | void | |
b4fe2683 JM |
117 | htab_delete (htab) |
118 | htab_t htab; | |
e2eaf477 | 119 | { |
b4fe2683 JM |
120 | int i; |
121 | if (htab->del_f) | |
122 | for (i = htab->size - 1; i >= 0; i--) | |
123 | { | |
124 | if (htab->entries[i] != EMPTY_ENTRY | |
125 | && htab->entries[i] != DELETED_ENTRY) | |
126 | (*htab->del_f) (htab->entries[i]); | |
127 | } | |
128 | ||
e2eaf477 ILT |
129 | free (htab->entries); |
130 | free (htab); | |
131 | } | |
132 | ||
133 | /* This function clears all entries in the given hash table. */ | |
134 | ||
135 | void | |
b4fe2683 JM |
136 | htab_empty (htab) |
137 | htab_t htab; | |
138 | { | |
139 | int i; | |
140 | if (htab->del_f) | |
141 | for (i = htab->size - 1; i >= 0; i--) | |
142 | { | |
143 | if (htab->entries[i] != EMPTY_ENTRY | |
144 | && htab->entries[i] != DELETED_ENTRY) | |
145 | (*htab->del_f) (htab->entries[i]); | |
146 | } | |
147 | ||
148 | memset (htab->entries, 0, htab->size * sizeof (void *)); | |
149 | } | |
150 | ||
151 | /* Similar to htab_find_slot, but without several unwanted side effects: | |
152 | - Does not call htab->eq_f when it finds an existing entry. | |
153 | - Does not change the count of elements/searches/collisions in the | |
154 | hash table. | |
155 | This function also assumes there are no deleted entries in the table. | |
156 | HASH is the hash value for the element to be inserted. */ | |
157 | static void ** | |
158 | find_empty_slot_for_expand (htab, hash) | |
159 | htab_t htab; | |
160 | unsigned int hash; | |
e2eaf477 | 161 | { |
b4fe2683 JM |
162 | size_t size = htab->size; |
163 | unsigned int hash2 = 1 + hash % (size - 2); | |
164 | unsigned int index = hash % size; | |
165 | ||
166 | for (;;) | |
167 | { | |
168 | void **slot = htab->entries + index; | |
169 | if (*slot == EMPTY_ENTRY) | |
170 | return slot; | |
171 | ||
172 | if (*slot == DELETED_ENTRY) | |
173 | abort (); | |
174 | ||
175 | index += hash2; | |
176 | if (index >= size) | |
177 | index -= size; | |
178 | } | |
e2eaf477 ILT |
179 | } |
180 | ||
181 | /* The following function changes size of memory allocated for the | |
182 | entries and repeatedly inserts the table elements. The occupancy | |
183 | of the table after the call will be about 50%. Naturally the hash | |
184 | table must already exist. Remember also that the place of the | |
185 | table entries is changed. */ | |
186 | ||
187 | static void | |
b4fe2683 JM |
188 | htab_expand (htab) |
189 | htab_t htab; | |
e2eaf477 | 190 | { |
b4fe2683 JM |
191 | void **oentries; |
192 | void **olimit; | |
193 | void **p; | |
194 | ||
195 | oentries = htab->entries; | |
196 | olimit = oentries + htab->size; | |
197 | ||
198 | htab->size = higher_prime_number (htab->size * 2); | |
199 | htab->entries = xcalloc (htab->size, sizeof (void **)); | |
200 | ||
201 | htab->n_elements -= htab->n_deleted; | |
202 | htab->n_deleted = 0; | |
203 | ||
204 | p = oentries; | |
205 | do | |
206 | { | |
207 | void *x = *p; | |
208 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) | |
209 | { | |
210 | void **q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x)); | |
211 | *q = x; | |
212 | } | |
213 | p++; | |
214 | } | |
215 | while (p < olimit); | |
216 | free (oentries); | |
e2eaf477 ILT |
217 | } |
218 | ||
b4fe2683 JM |
219 | /* This function searches for a hash table entry equal to the given |
220 | element. It cannot be used to insert or delete an element. */ | |
221 | ||
222 | void * | |
223 | htab_find_with_hash (htab, element, hash) | |
224 | htab_t htab; | |
225 | const void *element; | |
226 | unsigned int hash; | |
e2eaf477 | 227 | { |
b4fe2683 JM |
228 | unsigned int index, hash2; |
229 | size_t size; | |
e2eaf477 | 230 | |
b4fe2683 JM |
231 | htab->searches++; |
232 | size = htab->size; | |
233 | hash2 = 1 + hash % (size - 2); | |
234 | index = hash % size; | |
235 | ||
236 | for (;;) | |
e2eaf477 | 237 | { |
b4fe2683 JM |
238 | void *entry = htab->entries[index]; |
239 | if (entry == EMPTY_ENTRY) | |
240 | return NULL; | |
241 | else if (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element)) | |
242 | return entry; | |
243 | ||
244 | htab->collisions++; | |
245 | index += hash2; | |
246 | if (index >= size) | |
247 | index -= size; | |
e2eaf477 | 248 | } |
b4fe2683 JM |
249 | } |
250 | ||
251 | /* Like htab_find_slot_with_hash, but compute the hash value from the | |
252 | element. */ | |
253 | void * | |
254 | htab_find (htab, element) | |
255 | htab_t htab; | |
256 | const void *element; | |
257 | { | |
258 | return htab_find_with_hash (htab, element, (*htab->hash_f) (element)); | |
259 | } | |
260 | ||
261 | /* This function searches for a hash table slot containing an entry | |
262 | equal to the given element. To delete an entry, call this with | |
263 | INSERT = 0, then call htab_clear_slot on the slot returned (possibly | |
264 | after doing some checks). To insert an entry, call this with | |
265 | INSERT = 1, then write the value you want into the returned slot. */ | |
266 | ||
267 | void ** | |
268 | htab_find_slot_with_hash (htab, element, hash, insert) | |
269 | htab_t htab; | |
270 | const void *element; | |
271 | unsigned int hash; | |
272 | int insert; | |
273 | { | |
274 | void **first_deleted_slot; | |
275 | unsigned int index, hash2; | |
276 | size_t size; | |
277 | ||
278 | if (insert && htab->size * 3 <= htab->n_elements * 4) | |
279 | htab_expand (htab); | |
280 | ||
281 | size = htab->size; | |
282 | hash2 = 1 + hash % (size - 2); | |
283 | index = hash % size; | |
284 | ||
e2eaf477 | 285 | htab->searches++; |
b4fe2683 JM |
286 | first_deleted_slot = NULL; |
287 | ||
288 | for (;;) | |
e2eaf477 | 289 | { |
b4fe2683 JM |
290 | void *entry = htab->entries[index]; |
291 | if (entry == EMPTY_ENTRY) | |
292 | { | |
293 | if (!insert) | |
294 | return NULL; | |
295 | ||
296 | htab->n_elements++; | |
297 | ||
298 | if (first_deleted_slot) | |
e2eaf477 | 299 | { |
b4fe2683 JM |
300 | *first_deleted_slot = EMPTY_ENTRY; |
301 | return first_deleted_slot; | |
e2eaf477 | 302 | } |
b4fe2683 JM |
303 | |
304 | return &htab->entries[index]; | |
305 | } | |
306 | ||
307 | if (entry == DELETED_ENTRY) | |
308 | { | |
309 | if (!first_deleted_slot) | |
310 | first_deleted_slot = &htab->entries[index]; | |
311 | } | |
312 | else | |
313 | { | |
314 | if ((*htab->eq_f) (entry, element)) | |
315 | return &htab->entries[index]; | |
316 | } | |
317 | ||
318 | htab->collisions++; | |
319 | index += hash2; | |
320 | if (index >= size) | |
321 | index -= size; | |
e2eaf477 | 322 | } |
e2eaf477 ILT |
323 | } |
324 | ||
b4fe2683 JM |
325 | /* Like htab_find_slot_with_hash, but compute the hash value from the |
326 | element. */ | |
327 | void ** | |
328 | htab_find_slot (htab, element, insert) | |
329 | htab_t htab; | |
330 | const void *element; | |
331 | int insert; | |
332 | { | |
333 | return htab_find_slot_with_hash (htab, element, (*htab->hash_f) (element), | |
334 | insert); | |
335 | } | |
336 | ||
337 | /* This function deletes an element with the given value from hash | |
338 | table. If there is no matching element in the hash table, this | |
339 | function does nothing. */ | |
e2eaf477 ILT |
340 | |
341 | void | |
b4fe2683 JM |
342 | htab_remove_elt (htab, element) |
343 | htab_t htab; | |
344 | void *element; | |
e2eaf477 | 345 | { |
b4fe2683 JM |
346 | void **slot; |
347 | ||
348 | slot = htab_find_slot (htab, element, 0); | |
349 | if (*slot == EMPTY_ENTRY) | |
350 | return; | |
351 | ||
352 | if (htab->del_f) | |
353 | (*htab->del_f) (*slot); | |
e2eaf477 | 354 | |
b4fe2683 JM |
355 | *slot = DELETED_ENTRY; |
356 | htab->n_deleted++; | |
e2eaf477 ILT |
357 | } |
358 | ||
b4fe2683 JM |
359 | /* This function clears a specified slot in a hash table. It is |
360 | useful when you've already done the lookup and don't want to do it | |
361 | again. */ | |
e2eaf477 ILT |
362 | |
363 | void | |
b4fe2683 JM |
364 | htab_clear_slot (htab, slot) |
365 | htab_t htab; | |
366 | void **slot; | |
e2eaf477 ILT |
367 | { |
368 | if (slot < htab->entries || slot >= htab->entries + htab->size | |
369 | || *slot == EMPTY_ENTRY || *slot == DELETED_ENTRY) | |
370 | abort (); | |
b4fe2683 JM |
371 | if (htab->del_f) |
372 | (*htab->del_f) (*slot); | |
e2eaf477 | 373 | *slot = DELETED_ENTRY; |
b4fe2683 | 374 | htab->n_deleted++; |
e2eaf477 ILT |
375 | } |
376 | ||
377 | /* This function scans over the entire hash table calling | |
378 | CALLBACK for each live entry. If CALLBACK returns false, | |
379 | the iteration stops. INFO is passed as CALLBACK's second | |
380 | argument. */ | |
381 | ||
382 | void | |
b4fe2683 JM |
383 | htab_traverse (htab, callback, info) |
384 | htab_t htab; | |
385 | htab_trav callback; | |
e2eaf477 ILT |
386 | void *info; |
387 | { | |
b4fe2683 JM |
388 | void **slot, **limit; |
389 | slot = htab->entries; | |
390 | limit = slot + htab->size; | |
391 | do | |
392 | { | |
393 | void *x = *slot; | |
394 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) | |
395 | if (!(*callback) (slot, info)) | |
396 | break; | |
397 | } | |
398 | while (++slot < limit); | |
e2eaf477 ILT |
399 | } |
400 | ||
401 | /* The following function returns current size of given hash table. */ | |
402 | ||
403 | size_t | |
b4fe2683 JM |
404 | htab_size (htab) |
405 | htab_t htab; | |
e2eaf477 ILT |
406 | { |
407 | return htab->size; | |
408 | } | |
409 | ||
410 | /* The following function returns current number of elements in given | |
411 | hash table. */ | |
412 | ||
413 | size_t | |
b4fe2683 JM |
414 | htab_elements (htab) |
415 | htab_t htab; | |
e2eaf477 | 416 | { |
b4fe2683 | 417 | return htab->n_elements - htab->n_deleted; |
e2eaf477 ILT |
418 | } |
419 | ||
420 | /* The following function returns number of percents of fixed | |
421 | collisions during all work with given hash table. */ | |
422 | ||
b4fe2683 JM |
423 | double |
424 | htab_collisions (htab) | |
425 | htab_t htab; | |
e2eaf477 ILT |
426 | { |
427 | int searches; | |
428 | ||
429 | searches = htab->searches; | |
430 | if (searches == 0) | |
b4fe2683 JM |
431 | return 0.0; |
432 | return (double)htab->collisions / (double)searches; | |
e2eaf477 | 433 | } |