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a2f945c6 | 1 | /* An expandable hash tables datatype. |
74828682 | 2 | Copyright (C) 1999, 2000, 2001, 2002, 2003 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 | |
a4c9b97e MM |
74 | /* The following function returns a nearest prime number which is |
75 | greater than N, and near a power of two. */ | |
a2f945c6 VM |
76 | |
77 | static unsigned long | |
5194cf08 ZW |
78 | higher_prime_number (n) |
79 | unsigned long n; | |
a2f945c6 | 80 | { |
a4c9b97e MM |
81 | /* These are primes that are near, but slightly smaller than, a |
82 | power of two. */ | |
0be6abca | 83 | static const unsigned long primes[] = { |
f8a0ba8c MM |
84 | (unsigned long) 7, |
85 | (unsigned long) 13, | |
86 | (unsigned long) 31, | |
87 | (unsigned long) 61, | |
88 | (unsigned long) 127, | |
89 | (unsigned long) 251, | |
90 | (unsigned long) 509, | |
91 | (unsigned long) 1021, | |
92 | (unsigned long) 2039, | |
93 | (unsigned long) 4093, | |
94 | (unsigned long) 8191, | |
95 | (unsigned long) 16381, | |
96 | (unsigned long) 32749, | |
97 | (unsigned long) 65521, | |
98 | (unsigned long) 131071, | |
99 | (unsigned long) 262139, | |
100 | (unsigned long) 524287, | |
101 | (unsigned long) 1048573, | |
102 | (unsigned long) 2097143, | |
103 | (unsigned long) 4194301, | |
104 | (unsigned long) 8388593, | |
105 | (unsigned long) 16777213, | |
106 | (unsigned long) 33554393, | |
107 | (unsigned long) 67108859, | |
108 | (unsigned long) 134217689, | |
109 | (unsigned long) 268435399, | |
110 | (unsigned long) 536870909, | |
111 | (unsigned long) 1073741789, | |
112 | (unsigned long) 2147483647, | |
113 | /* 4294967291L */ | |
6e8afa99 | 114 | ((unsigned long) 2147483647) + ((unsigned long) 2147483644), |
a4c9b97e MM |
115 | }; |
116 | ||
0be6abca KG |
117 | const unsigned long *low = &primes[0]; |
118 | const unsigned long *high = &primes[sizeof(primes) / sizeof(primes[0])]; | |
a4c9b97e MM |
119 | |
120 | while (low != high) | |
121 | { | |
0be6abca | 122 | const unsigned long *mid = low + (high - low) / 2; |
a4c9b97e MM |
123 | if (n > *mid) |
124 | low = mid + 1; | |
125 | else | |
126 | high = mid; | |
127 | } | |
128 | ||
129 | /* If we've run out of primes, abort. */ | |
130 | if (n > *low) | |
131 | { | |
132 | fprintf (stderr, "Cannot find prime bigger than %lu\n", n); | |
133 | abort (); | |
134 | } | |
135 | ||
136 | return *low; | |
a2f945c6 VM |
137 | } |
138 | ||
18a94a2f MM |
139 | /* Returns a hash code for P. */ |
140 | ||
4feeaae3 | 141 | static hashval_t |
18a94a2f | 142 | hash_pointer (p) |
35e9340f | 143 | const PTR p; |
18a94a2f | 144 | { |
1d2da2e1 | 145 | return (hashval_t) ((long)p >> 3); |
18a94a2f MM |
146 | } |
147 | ||
148 | /* Returns non-zero if P1 and P2 are equal. */ | |
149 | ||
4feeaae3 | 150 | static int |
18a94a2f | 151 | eq_pointer (p1, p2) |
35e9340f HPN |
152 | const PTR p1; |
153 | const PTR p2; | |
18a94a2f MM |
154 | { |
155 | return p1 == p2; | |
156 | } | |
157 | ||
a2f945c6 VM |
158 | /* This function creates table with length slightly longer than given |
159 | source length. Created hash table is initiated as empty (all the | |
160 | hash table entries are EMPTY_ENTRY). The function returns the | |
e2500fed | 161 | created hash table, or NULL if memory allocation fails. */ |
a2f945c6 | 162 | |
5194cf08 | 163 | htab_t |
e2500fed | 164 | htab_create_alloc (size, hash_f, eq_f, del_f, alloc_f, free_f) |
a2f945c6 | 165 | size_t size; |
5194cf08 ZW |
166 | htab_hash hash_f; |
167 | htab_eq eq_f; | |
5dc9cffd | 168 | htab_del del_f; |
e2500fed GK |
169 | htab_alloc alloc_f; |
170 | htab_free free_f; | |
a2f945c6 | 171 | { |
5194cf08 | 172 | htab_t result; |
a2f945c6 VM |
173 | |
174 | size = higher_prime_number (size); | |
e2500fed | 175 | result = (htab_t) (*alloc_f) (1, sizeof (struct htab)); |
d50d20ec HPN |
176 | if (result == NULL) |
177 | return NULL; | |
e2500fed | 178 | result->entries = (PTR *) (*alloc_f) (size, sizeof (PTR)); |
d50d20ec HPN |
179 | if (result->entries == NULL) |
180 | { | |
e2500fed GK |
181 | if (free_f != NULL) |
182 | (*free_f) (result); | |
d50d20ec HPN |
183 | return NULL; |
184 | } | |
d50d20ec HPN |
185 | result->size = size; |
186 | result->hash_f = hash_f; | |
187 | result->eq_f = eq_f; | |
188 | result->del_f = del_f; | |
e2500fed GK |
189 | result->alloc_f = alloc_f; |
190 | result->free_f = free_f; | |
a2f945c6 VM |
191 | return result; |
192 | } | |
193 | ||
74828682 DJ |
194 | /* As above, but use the variants of alloc_f and free_f which accept |
195 | an extra argument. */ | |
196 | ||
197 | htab_t | |
198 | htab_create_alloc_ex (size, hash_f, eq_f, del_f, alloc_arg, alloc_f, | |
199 | free_f) | |
200 | size_t size; | |
201 | htab_hash hash_f; | |
202 | htab_eq eq_f; | |
203 | htab_del del_f; | |
204 | PTR alloc_arg; | |
205 | htab_alloc_with_arg alloc_f; | |
206 | htab_free_with_arg free_f; | |
207 | { | |
208 | htab_t result; | |
209 | ||
210 | size = higher_prime_number (size); | |
211 | result = (htab_t) (*alloc_f) (alloc_arg, 1, sizeof (struct htab)); | |
212 | if (result == NULL) | |
213 | return NULL; | |
214 | result->entries = (PTR *) (*alloc_f) (alloc_arg, size, sizeof (PTR)); | |
215 | if (result->entries == NULL) | |
216 | { | |
217 | if (free_f != NULL) | |
218 | (*free_f) (alloc_arg, result); | |
219 | return NULL; | |
220 | } | |
221 | result->size = size; | |
222 | result->hash_f = hash_f; | |
223 | result->eq_f = eq_f; | |
224 | result->del_f = del_f; | |
225 | result->alloc_arg = alloc_arg; | |
226 | result->alloc_with_arg_f = alloc_f; | |
227 | result->free_with_arg_f = free_f; | |
228 | return result; | |
229 | } | |
230 | ||
231 | /* Update the function pointers and allocation parameter in the htab_t. */ | |
232 | ||
233 | void | |
234 | htab_set_functions_ex (htab, hash_f, eq_f, del_f, alloc_arg, alloc_f, free_f) | |
235 | htab_t htab; | |
236 | htab_hash hash_f; | |
237 | htab_eq eq_f; | |
238 | htab_del del_f; | |
239 | PTR alloc_arg; | |
240 | htab_alloc_with_arg alloc_f; | |
241 | htab_free_with_arg free_f; | |
242 | { | |
243 | htab->hash_f = hash_f; | |
244 | htab->eq_f = eq_f; | |
245 | htab->del_f = del_f; | |
246 | htab->alloc_arg = alloc_arg; | |
247 | htab->alloc_with_arg_f = alloc_f; | |
248 | htab->free_with_arg_f = free_f; | |
249 | } | |
250 | ||
045b3a49 GK |
251 | /* These functions exist solely for backward compatibility. */ |
252 | ||
253 | #undef htab_create | |
254 | htab_t | |
255 | htab_create (size, hash_f, eq_f, del_f) | |
256 | size_t size; | |
257 | htab_hash hash_f; | |
258 | htab_eq eq_f; | |
259 | htab_del del_f; | |
260 | { | |
261 | return htab_create_alloc (size, hash_f, eq_f, del_f, xcalloc, free); | |
262 | } | |
263 | ||
264 | htab_t | |
265 | htab_try_create (size, hash_f, eq_f, del_f) | |
266 | size_t size; | |
267 | htab_hash hash_f; | |
268 | htab_eq eq_f; | |
269 | htab_del del_f; | |
270 | { | |
271 | return htab_create_alloc (size, hash_f, eq_f, del_f, calloc, free); | |
272 | } | |
273 | ||
a2f945c6 VM |
274 | /* This function frees all memory allocated for given hash table. |
275 | Naturally the hash table must already exist. */ | |
276 | ||
277 | void | |
5194cf08 ZW |
278 | htab_delete (htab) |
279 | htab_t htab; | |
a2f945c6 | 280 | { |
5dc9cffd | 281 | int i; |
e38992e8 | 282 | |
5dc9cffd ZW |
283 | if (htab->del_f) |
284 | for (i = htab->size - 1; i >= 0; i--) | |
e38992e8 RK |
285 | if (htab->entries[i] != EMPTY_ENTRY |
286 | && htab->entries[i] != DELETED_ENTRY) | |
287 | (*htab->del_f) (htab->entries[i]); | |
5dc9cffd | 288 | |
e2500fed GK |
289 | if (htab->free_f != NULL) |
290 | { | |
291 | (*htab->free_f) (htab->entries); | |
292 | (*htab->free_f) (htab); | |
293 | } | |
74828682 DJ |
294 | else if (htab->free_with_arg_f != NULL) |
295 | { | |
296 | (*htab->free_with_arg_f) (htab->alloc_arg, htab->entries); | |
297 | (*htab->free_with_arg_f) (htab->alloc_arg, htab); | |
298 | } | |
a2f945c6 VM |
299 | } |
300 | ||
301 | /* This function clears all entries in the given hash table. */ | |
302 | ||
303 | void | |
5194cf08 ZW |
304 | htab_empty (htab) |
305 | htab_t htab; | |
a2f945c6 | 306 | { |
5dc9cffd | 307 | int i; |
e38992e8 | 308 | |
5dc9cffd ZW |
309 | if (htab->del_f) |
310 | for (i = htab->size - 1; i >= 0; i--) | |
e38992e8 RK |
311 | if (htab->entries[i] != EMPTY_ENTRY |
312 | && htab->entries[i] != DELETED_ENTRY) | |
313 | (*htab->del_f) (htab->entries[i]); | |
5dc9cffd | 314 | |
35e9340f | 315 | memset (htab->entries, 0, htab->size * sizeof (PTR)); |
a2f945c6 VM |
316 | } |
317 | ||
8c5d513f BS |
318 | /* Similar to htab_find_slot, but without several unwanted side effects: |
319 | - Does not call htab->eq_f when it finds an existing entry. | |
320 | - Does not change the count of elements/searches/collisions in the | |
321 | hash table. | |
322 | This function also assumes there are no deleted entries in the table. | |
323 | HASH is the hash value for the element to be inserted. */ | |
e38992e8 | 324 | |
35e9340f | 325 | static PTR * |
8c5d513f BS |
326 | find_empty_slot_for_expand (htab, hash) |
327 | htab_t htab; | |
b13eb66b | 328 | hashval_t hash; |
8c5d513f BS |
329 | { |
330 | size_t size = htab->size; | |
8c5d513f | 331 | unsigned int index = hash % size; |
4fc4e478 RH |
332 | PTR *slot = htab->entries + index; |
333 | hashval_t hash2; | |
334 | ||
335 | if (*slot == EMPTY_ENTRY) | |
336 | return slot; | |
337 | else if (*slot == DELETED_ENTRY) | |
338 | abort (); | |
8c5d513f | 339 | |
4fc4e478 | 340 | hash2 = 1 + hash % (size - 2); |
8c5d513f BS |
341 | for (;;) |
342 | { | |
4fc4e478 RH |
343 | index += hash2; |
344 | if (index >= size) | |
345 | index -= size; | |
e38992e8 | 346 | |
4fc4e478 | 347 | slot = htab->entries + index; |
8c5d513f BS |
348 | if (*slot == EMPTY_ENTRY) |
349 | return slot; | |
e38992e8 | 350 | else if (*slot == DELETED_ENTRY) |
8c5d513f | 351 | abort (); |
8c5d513f BS |
352 | } |
353 | } | |
354 | ||
a2f945c6 VM |
355 | /* The following function changes size of memory allocated for the |
356 | entries and repeatedly inserts the table elements. The occupancy | |
357 | of the table after the call will be about 50%. Naturally the hash | |
358 | table must already exist. Remember also that the place of the | |
d50d20ec HPN |
359 | table entries is changed. If memory allocation failures are allowed, |
360 | this function will return zero, indicating that the table could not be | |
361 | expanded. If all goes well, it will return a non-zero value. */ | |
a2f945c6 | 362 | |
d50d20ec | 363 | static int |
5194cf08 ZW |
364 | htab_expand (htab) |
365 | htab_t htab; | |
a2f945c6 | 366 | { |
35e9340f HPN |
367 | PTR *oentries; |
368 | PTR *olimit; | |
369 | PTR *p; | |
e2500fed | 370 | PTR *nentries; |
120cdf68 | 371 | size_t nsize; |
5194cf08 ZW |
372 | |
373 | oentries = htab->entries; | |
374 | olimit = oentries + htab->size; | |
375 | ||
0a8e3de3 JH |
376 | /* Resize only when table after removal of unused elements is either |
377 | too full or too empty. */ | |
378 | if ((htab->n_elements - htab->n_deleted) * 2 > htab->size | |
379 | || (htab->n_elements - htab->n_deleted) * 8 < htab->size | |
380 | && htab->size > 32) | |
381 | nsize = higher_prime_number ((htab->n_elements - htab->n_deleted) * 2); | |
382 | else | |
383 | nsize = htab->size; | |
d50d20ec | 384 | |
74828682 DJ |
385 | if (htab->alloc_with_arg_f != NULL) |
386 | nentries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize, | |
387 | sizeof (PTR *)); | |
388 | else | |
389 | nentries = (PTR *) (*htab->alloc_f) (nsize, sizeof (PTR *)); | |
e2500fed GK |
390 | if (nentries == NULL) |
391 | return 0; | |
392 | htab->entries = nentries; | |
120cdf68 | 393 | htab->size = nsize; |
5194cf08 ZW |
394 | |
395 | htab->n_elements -= htab->n_deleted; | |
396 | htab->n_deleted = 0; | |
397 | ||
398 | p = oentries; | |
399 | do | |
400 | { | |
35e9340f | 401 | PTR x = *p; |
e38992e8 | 402 | |
5194cf08 ZW |
403 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) |
404 | { | |
35e9340f | 405 | PTR *q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x)); |
e38992e8 | 406 | |
5194cf08 ZW |
407 | *q = x; |
408 | } | |
e38992e8 | 409 | |
5194cf08 ZW |
410 | p++; |
411 | } | |
412 | while (p < olimit); | |
e38992e8 | 413 | |
e2500fed GK |
414 | if (htab->free_f != NULL) |
415 | (*htab->free_f) (oentries); | |
74828682 DJ |
416 | else if (htab->free_with_arg_f != NULL) |
417 | (*htab->free_with_arg_f) (htab->alloc_arg, oentries); | |
d50d20ec | 418 | return 1; |
a2f945c6 VM |
419 | } |
420 | ||
5194cf08 ZW |
421 | /* This function searches for a hash table entry equal to the given |
422 | element. It cannot be used to insert or delete an element. */ | |
423 | ||
35e9340f | 424 | PTR |
8c5d513f | 425 | htab_find_with_hash (htab, element, hash) |
5194cf08 | 426 | htab_t htab; |
35e9340f | 427 | const PTR element; |
b13eb66b | 428 | hashval_t hash; |
a2f945c6 | 429 | { |
b13eb66b MM |
430 | unsigned int index; |
431 | hashval_t hash2; | |
5194cf08 | 432 | size_t size; |
35e9340f | 433 | PTR entry; |
5194cf08 ZW |
434 | |
435 | htab->searches++; | |
436 | size = htab->size; | |
5194cf08 | 437 | index = hash % size; |
a2f945c6 | 438 | |
0194e877 ZW |
439 | entry = htab->entries[index]; |
440 | if (entry == EMPTY_ENTRY | |
441 | || (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
442 | return entry; | |
443 | ||
444 | hash2 = 1 + hash % (size - 2); | |
445 | ||
5194cf08 | 446 | for (;;) |
a2f945c6 | 447 | { |
5194cf08 ZW |
448 | htab->collisions++; |
449 | index += hash2; | |
450 | if (index >= size) | |
451 | index -= size; | |
0194e877 ZW |
452 | |
453 | entry = htab->entries[index]; | |
454 | if (entry == EMPTY_ENTRY | |
455 | || (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
456 | return entry; | |
a2f945c6 | 457 | } |
5194cf08 ZW |
458 | } |
459 | ||
8c5d513f BS |
460 | /* Like htab_find_slot_with_hash, but compute the hash value from the |
461 | element. */ | |
e38992e8 | 462 | |
35e9340f | 463 | PTR |
8c5d513f BS |
464 | htab_find (htab, element) |
465 | htab_t htab; | |
35e9340f | 466 | const PTR element; |
8c5d513f BS |
467 | { |
468 | return htab_find_with_hash (htab, element, (*htab->hash_f) (element)); | |
469 | } | |
470 | ||
5194cf08 ZW |
471 | /* This function searches for a hash table slot containing an entry |
472 | equal to the given element. To delete an entry, call this with | |
473 | INSERT = 0, then call htab_clear_slot on the slot returned (possibly | |
474 | after doing some checks). To insert an entry, call this with | |
d50d20ec HPN |
475 | INSERT = 1, then write the value you want into the returned slot. |
476 | When inserting an entry, NULL may be returned if memory allocation | |
477 | fails. */ | |
5194cf08 | 478 | |
35e9340f | 479 | PTR * |
8c5d513f | 480 | htab_find_slot_with_hash (htab, element, hash, insert) |
5194cf08 | 481 | htab_t htab; |
35e9340f | 482 | const PTR element; |
b13eb66b | 483 | hashval_t hash; |
e38992e8 | 484 | enum insert_option insert; |
5194cf08 | 485 | { |
35e9340f | 486 | PTR *first_deleted_slot; |
b13eb66b MM |
487 | unsigned int index; |
488 | hashval_t hash2; | |
5194cf08 | 489 | size_t size; |
4fc4e478 | 490 | PTR entry; |
5194cf08 | 491 | |
d50d20ec HPN |
492 | if (insert == INSERT && htab->size * 3 <= htab->n_elements * 4 |
493 | && htab_expand (htab) == 0) | |
494 | return NULL; | |
5194cf08 ZW |
495 | |
496 | size = htab->size; | |
5194cf08 ZW |
497 | index = hash % size; |
498 | ||
a2f945c6 | 499 | htab->searches++; |
5194cf08 ZW |
500 | first_deleted_slot = NULL; |
501 | ||
4fc4e478 RH |
502 | entry = htab->entries[index]; |
503 | if (entry == EMPTY_ENTRY) | |
504 | goto empty_entry; | |
505 | else if (entry == DELETED_ENTRY) | |
506 | first_deleted_slot = &htab->entries[index]; | |
507 | else if ((*htab->eq_f) (entry, element)) | |
508 | return &htab->entries[index]; | |
509 | ||
510 | hash2 = 1 + hash % (size - 2); | |
5194cf08 | 511 | for (;;) |
a2f945c6 | 512 | { |
4fc4e478 RH |
513 | htab->collisions++; |
514 | index += hash2; | |
515 | if (index >= size) | |
516 | index -= size; | |
517 | ||
518 | entry = htab->entries[index]; | |
5194cf08 | 519 | if (entry == EMPTY_ENTRY) |
4fc4e478 RH |
520 | goto empty_entry; |
521 | else if (entry == DELETED_ENTRY) | |
5194cf08 ZW |
522 | { |
523 | if (!first_deleted_slot) | |
524 | first_deleted_slot = &htab->entries[index]; | |
525 | } | |
4fc4e478 | 526 | else if ((*htab->eq_f) (entry, element)) |
e38992e8 | 527 | return &htab->entries[index]; |
a2f945c6 | 528 | } |
4fc4e478 RH |
529 | |
530 | empty_entry: | |
531 | if (insert == NO_INSERT) | |
532 | return NULL; | |
533 | ||
534 | htab->n_elements++; | |
535 | ||
536 | if (first_deleted_slot) | |
537 | { | |
538 | *first_deleted_slot = EMPTY_ENTRY; | |
539 | return first_deleted_slot; | |
540 | } | |
541 | ||
542 | return &htab->entries[index]; | |
a2f945c6 VM |
543 | } |
544 | ||
8c5d513f BS |
545 | /* Like htab_find_slot_with_hash, but compute the hash value from the |
546 | element. */ | |
e38992e8 | 547 | |
35e9340f | 548 | PTR * |
8c5d513f BS |
549 | htab_find_slot (htab, element, insert) |
550 | htab_t htab; | |
35e9340f | 551 | const PTR element; |
e38992e8 | 552 | enum insert_option insert; |
8c5d513f BS |
553 | { |
554 | return htab_find_slot_with_hash (htab, element, (*htab->hash_f) (element), | |
555 | insert); | |
556 | } | |
557 | ||
5194cf08 ZW |
558 | /* This function deletes an element with the given value from hash |
559 | table. If there is no matching element in the hash table, this | |
560 | function does nothing. */ | |
a2f945c6 VM |
561 | |
562 | void | |
5194cf08 ZW |
563 | htab_remove_elt (htab, element) |
564 | htab_t htab; | |
35e9340f | 565 | PTR element; |
a2f945c6 | 566 | { |
35e9340f | 567 | PTR *slot; |
a2f945c6 | 568 | |
e38992e8 | 569 | slot = htab_find_slot (htab, element, NO_INSERT); |
5194cf08 ZW |
570 | if (*slot == EMPTY_ENTRY) |
571 | return; | |
572 | ||
5dc9cffd ZW |
573 | if (htab->del_f) |
574 | (*htab->del_f) (*slot); | |
575 | ||
5194cf08 ZW |
576 | *slot = DELETED_ENTRY; |
577 | htab->n_deleted++; | |
a2f945c6 VM |
578 | } |
579 | ||
5194cf08 ZW |
580 | /* This function clears a specified slot in a hash table. It is |
581 | useful when you've already done the lookup and don't want to do it | |
582 | again. */ | |
ed38f5d5 ZW |
583 | |
584 | void | |
5194cf08 ZW |
585 | htab_clear_slot (htab, slot) |
586 | htab_t htab; | |
35e9340f | 587 | PTR *slot; |
ed38f5d5 ZW |
588 | { |
589 | if (slot < htab->entries || slot >= htab->entries + htab->size | |
590 | || *slot == EMPTY_ENTRY || *slot == DELETED_ENTRY) | |
591 | abort (); | |
e38992e8 | 592 | |
5dc9cffd ZW |
593 | if (htab->del_f) |
594 | (*htab->del_f) (*slot); | |
e38992e8 | 595 | |
ed38f5d5 | 596 | *slot = DELETED_ENTRY; |
5194cf08 | 597 | htab->n_deleted++; |
ed38f5d5 ZW |
598 | } |
599 | ||
600 | /* This function scans over the entire hash table calling | |
601 | CALLBACK for each live entry. If CALLBACK returns false, | |
602 | the iteration stops. INFO is passed as CALLBACK's second | |
603 | argument. */ | |
604 | ||
605 | void | |
5194cf08 ZW |
606 | htab_traverse (htab, callback, info) |
607 | htab_t htab; | |
608 | htab_trav callback; | |
35e9340f | 609 | PTR info; |
ed38f5d5 | 610 | { |
0a8e3de3 JH |
611 | PTR *slot; |
612 | PTR *limit; | |
613 | ||
614 | if ((htab->n_elements - htab->n_deleted) * 8 < htab->size) | |
615 | htab_expand (htab); | |
616 | ||
617 | slot = htab->entries; | |
618 | limit = slot + htab->size; | |
e38992e8 | 619 | |
5194cf08 ZW |
620 | do |
621 | { | |
35e9340f | 622 | PTR x = *slot; |
e38992e8 | 623 | |
5194cf08 | 624 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) |
8c5d513f | 625 | if (!(*callback) (slot, info)) |
5194cf08 ZW |
626 | break; |
627 | } | |
628 | while (++slot < limit); | |
ed38f5d5 ZW |
629 | } |
630 | ||
e38992e8 | 631 | /* Return the current size of given hash table. */ |
a2f945c6 VM |
632 | |
633 | size_t | |
5194cf08 ZW |
634 | htab_size (htab) |
635 | htab_t htab; | |
a2f945c6 VM |
636 | { |
637 | return htab->size; | |
638 | } | |
639 | ||
e38992e8 | 640 | /* Return the current number of elements in given hash table. */ |
a2f945c6 VM |
641 | |
642 | size_t | |
5194cf08 ZW |
643 | htab_elements (htab) |
644 | htab_t htab; | |
a2f945c6 | 645 | { |
5194cf08 | 646 | return htab->n_elements - htab->n_deleted; |
a2f945c6 VM |
647 | } |
648 | ||
e38992e8 RK |
649 | /* Return the fraction of fixed collisions during all work with given |
650 | hash table. */ | |
a2f945c6 | 651 | |
5194cf08 ZW |
652 | double |
653 | htab_collisions (htab) | |
654 | htab_t htab; | |
a2f945c6 | 655 | { |
e38992e8 | 656 | if (htab->searches == 0) |
5194cf08 | 657 | return 0.0; |
e38992e8 RK |
658 | |
659 | return (double) htab->collisions / (double) htab->searches; | |
a2f945c6 | 660 | } |
9e0ba685 | 661 | |
0ed5305d RH |
662 | /* Hash P as a null-terminated string. |
663 | ||
664 | Copied from gcc/hashtable.c. Zack had the following to say with respect | |
665 | to applicability, though note that unlike hashtable.c, this hash table | |
666 | implementation re-hashes rather than chain buckets. | |
667 | ||
668 | http://gcc.gnu.org/ml/gcc-patches/2001-08/msg01021.html | |
669 | From: Zack Weinberg <zackw@panix.com> | |
670 | Date: Fri, 17 Aug 2001 02:15:56 -0400 | |
671 | ||
672 | I got it by extracting all the identifiers from all the source code | |
673 | I had lying around in mid-1999, and testing many recurrences of | |
674 | the form "H_n = H_{n-1} * K + c_n * L + M" where K, L, M were either | |
675 | prime numbers or the appropriate identity. This was the best one. | |
676 | I don't remember exactly what constituted "best", except I was | |
677 | looking at bucket-length distributions mostly. | |
678 | ||
679 | So it should be very good at hashing identifiers, but might not be | |
680 | as good at arbitrary strings. | |
681 | ||
682 | I'll add that it thoroughly trounces the hash functions recommended | |
683 | for this use at http://burtleburtle.net/bob/hash/index.html, both | |
684 | on speed and bucket distribution. I haven't tried it against the | |
685 | function they just started using for Perl's hashes. */ | |
9e0ba685 RH |
686 | |
687 | hashval_t | |
688 | htab_hash_string (p) | |
689 | const PTR p; | |
690 | { | |
691 | const unsigned char *str = (const unsigned char *) p; | |
692 | hashval_t r = 0; | |
693 | unsigned char c; | |
694 | ||
695 | while ((c = *str++) != 0) | |
696 | r = r * 67 + c - 113; | |
697 | ||
698 | return r; | |
699 | } |