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a2f945c6 | 1 | /* An expandable hash tables datatype. |
b13eb66b | 2 | Copyright (C) 1999, 2000 Free Software Foundation, Inc. |
a2f945c6 VM |
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 | ||
6de9b8ff PDM |
38 | #include <sys/types.h> |
39 | ||
a2f945c6 VM |
40 | #ifdef HAVE_STDLIB_H |
41 | #include <stdlib.h> | |
42 | #endif | |
43 | ||
d11ec6f0 ZW |
44 | #ifdef HAVE_STRING_H |
45 | #include <string.h> | |
46 | #endif | |
47 | ||
36dd3a44 JL |
48 | #include <stdio.h> |
49 | ||
a2f945c6 VM |
50 | #include "libiberty.h" |
51 | #include "hashtab.h" | |
52 | ||
a2f945c6 VM |
53 | /* This macro defines reserved value for empty table entry. */ |
54 | ||
35e9340f | 55 | #define EMPTY_ENTRY ((PTR) 0) |
a2f945c6 VM |
56 | |
57 | /* This macro defines reserved value for table entry which contained | |
58 | a deleted element. */ | |
59 | ||
35e9340f | 60 | #define DELETED_ENTRY ((PTR) 1) |
a2f945c6 | 61 | |
0194e877 | 62 | static unsigned long higher_prime_number PARAMS ((unsigned long)); |
18a94a2f MM |
63 | static hashval_t hash_pointer PARAMS ((const void *)); |
64 | static int eq_pointer PARAMS ((const void *, const void *)); | |
d50d20ec | 65 | static int htab_expand PARAMS ((htab_t)); |
35e9340f | 66 | static PTR *find_empty_slot_for_expand PARAMS ((htab_t, hashval_t)); |
18a94a2f MM |
67 | |
68 | /* At some point, we could make these be NULL, and modify the | |
69 | hash-table routines to handle NULL specially; that would avoid | |
70 | function-call overhead for the common case of hashing pointers. */ | |
71 | htab_hash htab_hash_pointer = hash_pointer; | |
72 | htab_eq htab_eq_pointer = eq_pointer; | |
0194e877 | 73 | |
a2f945c6 | 74 | /* The following function returns the nearest prime number which is |
e38992e8 | 75 | greater than a given source number, N. */ |
a2f945c6 VM |
76 | |
77 | static unsigned long | |
5194cf08 ZW |
78 | higher_prime_number (n) |
79 | unsigned long n; | |
a2f945c6 VM |
80 | { |
81 | unsigned long i; | |
82 | ||
e38992e8 RK |
83 | /* Ensure we have a larger number and then force to odd. */ |
84 | n++; | |
85 | n |= 0x01; | |
86 | ||
87 | /* All odd numbers < 9 are prime. */ | |
5194cf08 | 88 | if (n < 9) |
e38992e8 RK |
89 | return n; |
90 | ||
91 | /* Otherwise find the next prime using a sieve. */ | |
5194cf08 ZW |
92 | |
93 | next: | |
e38992e8 RK |
94 | |
95 | for (i = 3; i * i <= n; i += 2) | |
96 | if (n % i == 0) | |
97 | { | |
98 | n += 2; | |
99 | goto next; | |
100 | } | |
5194cf08 ZW |
101 | |
102 | return n; | |
a2f945c6 VM |
103 | } |
104 | ||
18a94a2f MM |
105 | /* Returns a hash code for P. */ |
106 | ||
4feeaae3 | 107 | static hashval_t |
18a94a2f | 108 | hash_pointer (p) |
35e9340f | 109 | const PTR p; |
18a94a2f | 110 | { |
1d2da2e1 | 111 | return (hashval_t) ((long)p >> 3); |
18a94a2f MM |
112 | } |
113 | ||
114 | /* Returns non-zero if P1 and P2 are equal. */ | |
115 | ||
4feeaae3 | 116 | static int |
18a94a2f | 117 | eq_pointer (p1, p2) |
35e9340f HPN |
118 | const PTR p1; |
119 | const PTR p2; | |
18a94a2f MM |
120 | { |
121 | return p1 == p2; | |
122 | } | |
123 | ||
a2f945c6 VM |
124 | /* This function creates table with length slightly longer than given |
125 | source length. Created hash table is initiated as empty (all the | |
126 | hash table entries are EMPTY_ENTRY). The function returns the | |
d50d20ec | 127 | created hash table. Memory allocation must not fail. */ |
a2f945c6 | 128 | |
5194cf08 | 129 | htab_t |
5dc9cffd | 130 | htab_create (size, hash_f, eq_f, del_f) |
a2f945c6 | 131 | size_t size; |
5194cf08 ZW |
132 | htab_hash hash_f; |
133 | htab_eq eq_f; | |
5dc9cffd | 134 | htab_del del_f; |
a2f945c6 | 135 | { |
5194cf08 | 136 | htab_t result; |
a2f945c6 VM |
137 | |
138 | size = higher_prime_number (size); | |
5194cf08 | 139 | result = (htab_t) xcalloc (1, sizeof (struct htab)); |
35e9340f | 140 | result->entries = (PTR *) xcalloc (size, sizeof (PTR)); |
a2f945c6 | 141 | result->size = size; |
5194cf08 ZW |
142 | result->hash_f = hash_f; |
143 | result->eq_f = eq_f; | |
5dc9cffd | 144 | result->del_f = del_f; |
d50d20ec HPN |
145 | result->return_allocation_failure = 0; |
146 | return result; | |
147 | } | |
148 | ||
149 | /* This function creates table with length slightly longer than given | |
150 | source length. The created hash table is initiated as empty (all the | |
151 | hash table entries are EMPTY_ENTRY). The function returns the created | |
152 | hash table. Memory allocation may fail; it may return NULL. */ | |
153 | ||
154 | htab_t | |
155 | htab_try_create (size, hash_f, eq_f, del_f) | |
156 | size_t size; | |
157 | htab_hash hash_f; | |
158 | htab_eq eq_f; | |
159 | htab_del del_f; | |
160 | { | |
161 | htab_t result; | |
162 | ||
163 | size = higher_prime_number (size); | |
164 | result = (htab_t) calloc (1, sizeof (struct htab)); | |
165 | if (result == NULL) | |
166 | return NULL; | |
167 | ||
168 | result->entries = (PTR *) calloc (size, sizeof (PTR)); | |
169 | if (result->entries == NULL) | |
170 | { | |
171 | free (result); | |
172 | return NULL; | |
173 | } | |
174 | ||
175 | result->size = size; | |
176 | result->hash_f = hash_f; | |
177 | result->eq_f = eq_f; | |
178 | result->del_f = del_f; | |
179 | result->return_allocation_failure = 1; | |
a2f945c6 VM |
180 | return result; |
181 | } | |
182 | ||
183 | /* This function frees all memory allocated for given hash table. | |
184 | Naturally the hash table must already exist. */ | |
185 | ||
186 | void | |
5194cf08 ZW |
187 | htab_delete (htab) |
188 | htab_t htab; | |
a2f945c6 | 189 | { |
5dc9cffd | 190 | int i; |
e38992e8 | 191 | |
5dc9cffd ZW |
192 | if (htab->del_f) |
193 | for (i = htab->size - 1; i >= 0; i--) | |
e38992e8 RK |
194 | if (htab->entries[i] != EMPTY_ENTRY |
195 | && htab->entries[i] != DELETED_ENTRY) | |
196 | (*htab->del_f) (htab->entries[i]); | |
5dc9cffd | 197 | |
a2f945c6 VM |
198 | free (htab->entries); |
199 | free (htab); | |
200 | } | |
201 | ||
202 | /* This function clears all entries in the given hash table. */ | |
203 | ||
204 | void | |
5194cf08 ZW |
205 | htab_empty (htab) |
206 | htab_t htab; | |
a2f945c6 | 207 | { |
5dc9cffd | 208 | int i; |
e38992e8 | 209 | |
5dc9cffd ZW |
210 | if (htab->del_f) |
211 | for (i = htab->size - 1; i >= 0; i--) | |
e38992e8 RK |
212 | if (htab->entries[i] != EMPTY_ENTRY |
213 | && htab->entries[i] != DELETED_ENTRY) | |
214 | (*htab->del_f) (htab->entries[i]); | |
5dc9cffd | 215 | |
35e9340f | 216 | memset (htab->entries, 0, htab->size * sizeof (PTR)); |
a2f945c6 VM |
217 | } |
218 | ||
8c5d513f BS |
219 | /* Similar to htab_find_slot, but without several unwanted side effects: |
220 | - Does not call htab->eq_f when it finds an existing entry. | |
221 | - Does not change the count of elements/searches/collisions in the | |
222 | hash table. | |
223 | This function also assumes there are no deleted entries in the table. | |
224 | HASH is the hash value for the element to be inserted. */ | |
e38992e8 | 225 | |
35e9340f | 226 | static PTR * |
8c5d513f BS |
227 | find_empty_slot_for_expand (htab, hash) |
228 | htab_t htab; | |
b13eb66b | 229 | hashval_t hash; |
8c5d513f BS |
230 | { |
231 | size_t size = htab->size; | |
b13eb66b | 232 | hashval_t hash2 = 1 + hash % (size - 2); |
8c5d513f BS |
233 | unsigned int index = hash % size; |
234 | ||
235 | for (;;) | |
236 | { | |
35e9340f | 237 | PTR *slot = htab->entries + index; |
e38992e8 | 238 | |
8c5d513f BS |
239 | if (*slot == EMPTY_ENTRY) |
240 | return slot; | |
e38992e8 | 241 | else if (*slot == DELETED_ENTRY) |
8c5d513f BS |
242 | abort (); |
243 | ||
244 | index += hash2; | |
245 | if (index >= size) | |
246 | index -= size; | |
247 | } | |
248 | } | |
249 | ||
a2f945c6 VM |
250 | /* The following function changes size of memory allocated for the |
251 | entries and repeatedly inserts the table elements. The occupancy | |
252 | of the table after the call will be about 50%. Naturally the hash | |
253 | table must already exist. Remember also that the place of the | |
d50d20ec HPN |
254 | table entries is changed. If memory allocation failures are allowed, |
255 | this function will return zero, indicating that the table could not be | |
256 | expanded. If all goes well, it will return a non-zero value. */ | |
a2f945c6 | 257 | |
d50d20ec | 258 | static int |
5194cf08 ZW |
259 | htab_expand (htab) |
260 | htab_t htab; | |
a2f945c6 | 261 | { |
35e9340f HPN |
262 | PTR *oentries; |
263 | PTR *olimit; | |
264 | PTR *p; | |
5194cf08 ZW |
265 | |
266 | oentries = htab->entries; | |
267 | olimit = oentries + htab->size; | |
268 | ||
269 | htab->size = higher_prime_number (htab->size * 2); | |
d50d20ec HPN |
270 | |
271 | if (htab->return_allocation_failure) | |
272 | { | |
273 | PTR *nentries = (PTR *) calloc (htab->size, sizeof (PTR *)); | |
274 | if (nentries == NULL) | |
275 | return 0; | |
276 | htab->entries = nentries; | |
277 | } | |
278 | else | |
279 | htab->entries = (PTR *) xcalloc (htab->size, sizeof (PTR *)); | |
5194cf08 ZW |
280 | |
281 | htab->n_elements -= htab->n_deleted; | |
282 | htab->n_deleted = 0; | |
283 | ||
284 | p = oentries; | |
285 | do | |
286 | { | |
35e9340f | 287 | PTR x = *p; |
e38992e8 | 288 | |
5194cf08 ZW |
289 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) |
290 | { | |
35e9340f | 291 | PTR *q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x)); |
e38992e8 | 292 | |
5194cf08 ZW |
293 | *q = x; |
294 | } | |
e38992e8 | 295 | |
5194cf08 ZW |
296 | p++; |
297 | } | |
298 | while (p < olimit); | |
e38992e8 | 299 | |
5194cf08 | 300 | free (oentries); |
d50d20ec | 301 | return 1; |
a2f945c6 VM |
302 | } |
303 | ||
5194cf08 ZW |
304 | /* This function searches for a hash table entry equal to the given |
305 | element. It cannot be used to insert or delete an element. */ | |
306 | ||
35e9340f | 307 | PTR |
8c5d513f | 308 | htab_find_with_hash (htab, element, hash) |
5194cf08 | 309 | htab_t htab; |
35e9340f | 310 | const PTR element; |
b13eb66b | 311 | hashval_t hash; |
a2f945c6 | 312 | { |
b13eb66b MM |
313 | unsigned int index; |
314 | hashval_t hash2; | |
5194cf08 | 315 | size_t size; |
35e9340f | 316 | PTR entry; |
5194cf08 ZW |
317 | |
318 | htab->searches++; | |
319 | size = htab->size; | |
5194cf08 | 320 | index = hash % size; |
a2f945c6 | 321 | |
0194e877 ZW |
322 | entry = htab->entries[index]; |
323 | if (entry == EMPTY_ENTRY | |
324 | || (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
325 | return entry; | |
326 | ||
327 | hash2 = 1 + hash % (size - 2); | |
328 | ||
5194cf08 | 329 | for (;;) |
a2f945c6 | 330 | { |
5194cf08 ZW |
331 | htab->collisions++; |
332 | index += hash2; | |
333 | if (index >= size) | |
334 | index -= size; | |
0194e877 ZW |
335 | |
336 | entry = htab->entries[index]; | |
337 | if (entry == EMPTY_ENTRY | |
338 | || (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
339 | return entry; | |
a2f945c6 | 340 | } |
5194cf08 ZW |
341 | } |
342 | ||
8c5d513f BS |
343 | /* Like htab_find_slot_with_hash, but compute the hash value from the |
344 | element. */ | |
e38992e8 | 345 | |
35e9340f | 346 | PTR |
8c5d513f BS |
347 | htab_find (htab, element) |
348 | htab_t htab; | |
35e9340f | 349 | const PTR element; |
8c5d513f BS |
350 | { |
351 | return htab_find_with_hash (htab, element, (*htab->hash_f) (element)); | |
352 | } | |
353 | ||
5194cf08 ZW |
354 | /* This function searches for a hash table slot containing an entry |
355 | equal to the given element. To delete an entry, call this with | |
356 | INSERT = 0, then call htab_clear_slot on the slot returned (possibly | |
357 | after doing some checks). To insert an entry, call this with | |
d50d20ec HPN |
358 | INSERT = 1, then write the value you want into the returned slot. |
359 | When inserting an entry, NULL may be returned if memory allocation | |
360 | fails. */ | |
5194cf08 | 361 | |
35e9340f | 362 | PTR * |
8c5d513f | 363 | htab_find_slot_with_hash (htab, element, hash, insert) |
5194cf08 | 364 | htab_t htab; |
35e9340f | 365 | const PTR element; |
b13eb66b | 366 | hashval_t hash; |
e38992e8 | 367 | enum insert_option insert; |
5194cf08 | 368 | { |
35e9340f | 369 | PTR *first_deleted_slot; |
b13eb66b MM |
370 | unsigned int index; |
371 | hashval_t hash2; | |
5194cf08 ZW |
372 | size_t size; |
373 | ||
d50d20ec HPN |
374 | if (insert == INSERT && htab->size * 3 <= htab->n_elements * 4 |
375 | && htab_expand (htab) == 0) | |
376 | return NULL; | |
5194cf08 ZW |
377 | |
378 | size = htab->size; | |
5194cf08 ZW |
379 | hash2 = 1 + hash % (size - 2); |
380 | index = hash % size; | |
381 | ||
a2f945c6 | 382 | htab->searches++; |
5194cf08 ZW |
383 | first_deleted_slot = NULL; |
384 | ||
385 | for (;;) | |
a2f945c6 | 386 | { |
35e9340f | 387 | PTR entry = htab->entries[index]; |
5194cf08 ZW |
388 | if (entry == EMPTY_ENTRY) |
389 | { | |
e38992e8 | 390 | if (insert == NO_INSERT) |
5194cf08 ZW |
391 | return NULL; |
392 | ||
393 | htab->n_elements++; | |
394 | ||
395 | if (first_deleted_slot) | |
a2f945c6 | 396 | { |
5194cf08 ZW |
397 | *first_deleted_slot = EMPTY_ENTRY; |
398 | return first_deleted_slot; | |
a2f945c6 | 399 | } |
5194cf08 ZW |
400 | |
401 | return &htab->entries[index]; | |
402 | } | |
403 | ||
404 | if (entry == DELETED_ENTRY) | |
405 | { | |
406 | if (!first_deleted_slot) | |
407 | first_deleted_slot = &htab->entries[index]; | |
408 | } | |
e38992e8 RK |
409 | else if ((*htab->eq_f) (entry, element)) |
410 | return &htab->entries[index]; | |
5194cf08 ZW |
411 | |
412 | htab->collisions++; | |
413 | index += hash2; | |
414 | if (index >= size) | |
415 | index -= size; | |
a2f945c6 | 416 | } |
a2f945c6 VM |
417 | } |
418 | ||
8c5d513f BS |
419 | /* Like htab_find_slot_with_hash, but compute the hash value from the |
420 | element. */ | |
e38992e8 | 421 | |
35e9340f | 422 | PTR * |
8c5d513f BS |
423 | htab_find_slot (htab, element, insert) |
424 | htab_t htab; | |
35e9340f | 425 | const PTR element; |
e38992e8 | 426 | enum insert_option insert; |
8c5d513f BS |
427 | { |
428 | return htab_find_slot_with_hash (htab, element, (*htab->hash_f) (element), | |
429 | insert); | |
430 | } | |
431 | ||
5194cf08 ZW |
432 | /* This function deletes an element with the given value from hash |
433 | table. If there is no matching element in the hash table, this | |
434 | function does nothing. */ | |
a2f945c6 VM |
435 | |
436 | void | |
5194cf08 ZW |
437 | htab_remove_elt (htab, element) |
438 | htab_t htab; | |
35e9340f | 439 | PTR element; |
a2f945c6 | 440 | { |
35e9340f | 441 | PTR *slot; |
a2f945c6 | 442 | |
e38992e8 | 443 | slot = htab_find_slot (htab, element, NO_INSERT); |
5194cf08 ZW |
444 | if (*slot == EMPTY_ENTRY) |
445 | return; | |
446 | ||
5dc9cffd ZW |
447 | if (htab->del_f) |
448 | (*htab->del_f) (*slot); | |
449 | ||
5194cf08 ZW |
450 | *slot = DELETED_ENTRY; |
451 | htab->n_deleted++; | |
a2f945c6 VM |
452 | } |
453 | ||
5194cf08 ZW |
454 | /* This function clears a specified slot in a hash table. It is |
455 | useful when you've already done the lookup and don't want to do it | |
456 | again. */ | |
ed38f5d5 ZW |
457 | |
458 | void | |
5194cf08 ZW |
459 | htab_clear_slot (htab, slot) |
460 | htab_t htab; | |
35e9340f | 461 | PTR *slot; |
ed38f5d5 ZW |
462 | { |
463 | if (slot < htab->entries || slot >= htab->entries + htab->size | |
464 | || *slot == EMPTY_ENTRY || *slot == DELETED_ENTRY) | |
465 | abort (); | |
e38992e8 | 466 | |
5dc9cffd ZW |
467 | if (htab->del_f) |
468 | (*htab->del_f) (*slot); | |
e38992e8 | 469 | |
ed38f5d5 | 470 | *slot = DELETED_ENTRY; |
5194cf08 | 471 | htab->n_deleted++; |
ed38f5d5 ZW |
472 | } |
473 | ||
474 | /* This function scans over the entire hash table calling | |
475 | CALLBACK for each live entry. If CALLBACK returns false, | |
476 | the iteration stops. INFO is passed as CALLBACK's second | |
477 | argument. */ | |
478 | ||
479 | void | |
5194cf08 ZW |
480 | htab_traverse (htab, callback, info) |
481 | htab_t htab; | |
482 | htab_trav callback; | |
35e9340f | 483 | PTR info; |
ed38f5d5 | 484 | { |
35e9340f HPN |
485 | PTR *slot = htab->entries; |
486 | PTR *limit = slot + htab->size; | |
e38992e8 | 487 | |
5194cf08 ZW |
488 | do |
489 | { | |
35e9340f | 490 | PTR x = *slot; |
e38992e8 | 491 | |
5194cf08 | 492 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) |
8c5d513f | 493 | if (!(*callback) (slot, info)) |
5194cf08 ZW |
494 | break; |
495 | } | |
496 | while (++slot < limit); | |
ed38f5d5 ZW |
497 | } |
498 | ||
e38992e8 | 499 | /* Return the current size of given hash table. */ |
a2f945c6 VM |
500 | |
501 | size_t | |
5194cf08 ZW |
502 | htab_size (htab) |
503 | htab_t htab; | |
a2f945c6 VM |
504 | { |
505 | return htab->size; | |
506 | } | |
507 | ||
e38992e8 | 508 | /* Return the current number of elements in given hash table. */ |
a2f945c6 VM |
509 | |
510 | size_t | |
5194cf08 ZW |
511 | htab_elements (htab) |
512 | htab_t htab; | |
a2f945c6 | 513 | { |
5194cf08 | 514 | return htab->n_elements - htab->n_deleted; |
a2f945c6 VM |
515 | } |
516 | ||
e38992e8 RK |
517 | /* Return the fraction of fixed collisions during all work with given |
518 | hash table. */ | |
a2f945c6 | 519 | |
5194cf08 ZW |
520 | double |
521 | htab_collisions (htab) | |
522 | htab_t htab; | |
a2f945c6 | 523 | { |
e38992e8 | 524 | if (htab->searches == 0) |
5194cf08 | 525 | return 0.0; |
e38992e8 RK |
526 | |
527 | return (double) htab->collisions / (double) htab->searches; | |
a2f945c6 | 528 | } |