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e2eaf477 | 1 | /* An expandable hash tables datatype. |
5f9624e3 | 2 | Copyright (C) 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc. |
e2eaf477 ILT |
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 | ||
e0f3df8f | 55 | #define EMPTY_ENTRY ((PTR) 0) |
e2eaf477 ILT |
56 | |
57 | /* This macro defines reserved value for table entry which contained | |
58 | a deleted element. */ | |
59 | ||
e0f3df8f | 60 | #define DELETED_ENTRY ((PTR) 1) |
e2eaf477 | 61 | |
eb383413 L |
62 | static unsigned long higher_prime_number PARAMS ((unsigned long)); |
63 | static hashval_t hash_pointer PARAMS ((const void *)); | |
64 | static int eq_pointer PARAMS ((const void *, const void *)); | |
99a4c1bd | 65 | static int htab_expand PARAMS ((htab_t)); |
e0f3df8f | 66 | static PTR *find_empty_slot_for_expand PARAMS ((htab_t, hashval_t)); |
eb383413 L |
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; | |
73 | ||
5ca0f83d DD |
74 | /* The following function returns a nearest prime number which is |
75 | greater than N, and near a power of two. */ | |
e2eaf477 ILT |
76 | |
77 | static unsigned long | |
b4fe2683 JM |
78 | higher_prime_number (n) |
79 | unsigned long n; | |
e2eaf477 | 80 | { |
5ca0f83d DD |
81 | /* These are primes that are near, but slightly smaller than, a |
82 | power of two. */ | |
e6450fe5 | 83 | static const unsigned long primes[] = { |
b1e51b3c DD |
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 */ | |
06b0287c | 114 | ((unsigned long) 2147483647) + ((unsigned long) 2147483644), |
5ca0f83d DD |
115 | }; |
116 | ||
e6450fe5 DD |
117 | const unsigned long *low = &primes[0]; |
118 | const unsigned long *high = &primes[sizeof(primes) / sizeof(primes[0])]; | |
5ca0f83d DD |
119 | |
120 | while (low != high) | |
121 | { | |
e6450fe5 | 122 | const unsigned long *mid = low + (high - low) / 2; |
5ca0f83d DD |
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; | |
e2eaf477 ILT |
137 | } |
138 | ||
eb383413 L |
139 | /* Returns a hash code for P. */ |
140 | ||
141 | static hashval_t | |
142 | hash_pointer (p) | |
e0f3df8f | 143 | const PTR p; |
eb383413 L |
144 | { |
145 | return (hashval_t) ((long)p >> 3); | |
146 | } | |
147 | ||
148 | /* Returns non-zero if P1 and P2 are equal. */ | |
149 | ||
150 | static int | |
151 | eq_pointer (p1, p2) | |
e0f3df8f HPN |
152 | const PTR p1; |
153 | const PTR p2; | |
eb383413 L |
154 | { |
155 | return p1 == p2; | |
156 | } | |
157 | ||
e2eaf477 ILT |
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 | |
18893690 | 161 | created hash table, or NULL if memory allocation fails. */ |
e2eaf477 | 162 | |
b4fe2683 | 163 | htab_t |
18893690 | 164 | htab_create_alloc (size, hash_f, eq_f, del_f, alloc_f, free_f) |
e2eaf477 | 165 | size_t size; |
b4fe2683 JM |
166 | htab_hash hash_f; |
167 | htab_eq eq_f; | |
168 | htab_del del_f; | |
18893690 DD |
169 | htab_alloc alloc_f; |
170 | htab_free free_f; | |
e2eaf477 | 171 | { |
b4fe2683 | 172 | htab_t result; |
e2eaf477 ILT |
173 | |
174 | size = higher_prime_number (size); | |
18893690 DD |
175 | result = (htab_t) (*alloc_f) (1, sizeof (struct htab)); |
176 | if (result == NULL) | |
177 | return NULL; | |
178 | result->entries = (PTR *) (*alloc_f) (size, sizeof (PTR)); | |
179 | if (result->entries == NULL) | |
180 | { | |
181 | if (free_f != NULL) | |
182 | (*free_f) (result); | |
183 | return NULL; | |
184 | } | |
e2eaf477 | 185 | result->size = size; |
b4fe2683 JM |
186 | result->hash_f = hash_f; |
187 | result->eq_f = eq_f; | |
188 | result->del_f = del_f; | |
18893690 DD |
189 | result->alloc_f = alloc_f; |
190 | result->free_f = free_f; | |
99a4c1bd HPN |
191 | return result; |
192 | } | |
193 | ||
5f9624e3 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 | ||
18893690 | 251 | /* These functions exist solely for backward compatibility. */ |
99a4c1bd | 252 | |
18893690 | 253 | #undef htab_create |
99a4c1bd | 254 | htab_t |
18893690 | 255 | htab_create (size, hash_f, eq_f, del_f) |
99a4c1bd HPN |
256 | size_t size; |
257 | htab_hash hash_f; | |
258 | htab_eq eq_f; | |
259 | htab_del del_f; | |
260 | { | |
18893690 DD |
261 | return htab_create_alloc (size, hash_f, eq_f, del_f, xcalloc, free); |
262 | } | |
99a4c1bd | 263 | |
18893690 DD |
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); | |
e2eaf477 ILT |
272 | } |
273 | ||
274 | /* This function frees all memory allocated for given hash table. | |
275 | Naturally the hash table must already exist. */ | |
276 | ||
277 | void | |
b4fe2683 JM |
278 | htab_delete (htab) |
279 | htab_t htab; | |
e2eaf477 | 280 | { |
b4fe2683 | 281 | int i; |
eb383413 | 282 | |
b4fe2683 JM |
283 | if (htab->del_f) |
284 | for (i = htab->size - 1; i >= 0; i--) | |
eb383413 L |
285 | if (htab->entries[i] != EMPTY_ENTRY |
286 | && htab->entries[i] != DELETED_ENTRY) | |
287 | (*htab->del_f) (htab->entries[i]); | |
b4fe2683 | 288 | |
18893690 DD |
289 | if (htab->free_f != NULL) |
290 | { | |
291 | (*htab->free_f) (htab->entries); | |
292 | (*htab->free_f) (htab); | |
293 | } | |
5f9624e3 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 | } | |
e2eaf477 ILT |
299 | } |
300 | ||
301 | /* This function clears all entries in the given hash table. */ | |
302 | ||
303 | void | |
b4fe2683 JM |
304 | htab_empty (htab) |
305 | htab_t htab; | |
306 | { | |
307 | int i; | |
eb383413 | 308 | |
b4fe2683 JM |
309 | if (htab->del_f) |
310 | for (i = htab->size - 1; i >= 0; i--) | |
eb383413 L |
311 | if (htab->entries[i] != EMPTY_ENTRY |
312 | && htab->entries[i] != DELETED_ENTRY) | |
313 | (*htab->del_f) (htab->entries[i]); | |
b4fe2683 | 314 | |
e0f3df8f | 315 | memset (htab->entries, 0, htab->size * sizeof (PTR)); |
b4fe2683 JM |
316 | } |
317 | ||
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. */ | |
eb383413 | 324 | |
e0f3df8f | 325 | static PTR * |
b4fe2683 JM |
326 | find_empty_slot_for_expand (htab, hash) |
327 | htab_t htab; | |
eb383413 | 328 | hashval_t hash; |
e2eaf477 | 329 | { |
b4fe2683 | 330 | size_t size = htab->size; |
b4fe2683 | 331 | unsigned int index = hash % size; |
b1c933fc 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 (); | |
b4fe2683 | 339 | |
b1c933fc | 340 | hash2 = 1 + hash % (size - 2); |
b4fe2683 JM |
341 | for (;;) |
342 | { | |
b1c933fc RH |
343 | index += hash2; |
344 | if (index >= size) | |
345 | index -= size; | |
eb383413 | 346 | |
b1c933fc | 347 | slot = htab->entries + index; |
b4fe2683 JM |
348 | if (*slot == EMPTY_ENTRY) |
349 | return slot; | |
eb383413 | 350 | else if (*slot == DELETED_ENTRY) |
b4fe2683 | 351 | abort (); |
b4fe2683 | 352 | } |
e2eaf477 ILT |
353 | } |
354 | ||
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 | |
99a4c1bd 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. */ | |
e2eaf477 | 362 | |
99a4c1bd | 363 | static int |
b4fe2683 JM |
364 | htab_expand (htab) |
365 | htab_t htab; | |
e2eaf477 | 366 | { |
e0f3df8f HPN |
367 | PTR *oentries; |
368 | PTR *olimit; | |
369 | PTR *p; | |
18893690 | 370 | PTR *nentries; |
eed2b28c | 371 | size_t nsize; |
b4fe2683 JM |
372 | |
373 | oentries = htab->entries; | |
374 | olimit = oentries + htab->size; | |
375 | ||
eed2b28c | 376 | nsize = higher_prime_number (htab->size * 2); |
99a4c1bd | 377 | |
5f9624e3 DJ |
378 | if (htab->alloc_with_arg_f != NULL) |
379 | nentries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize, | |
380 | sizeof (PTR *)); | |
381 | else | |
382 | nentries = (PTR *) (*htab->alloc_f) (nsize, sizeof (PTR *)); | |
18893690 DD |
383 | if (nentries == NULL) |
384 | return 0; | |
385 | htab->entries = nentries; | |
eed2b28c | 386 | htab->size = nsize; |
b4fe2683 JM |
387 | |
388 | htab->n_elements -= htab->n_deleted; | |
389 | htab->n_deleted = 0; | |
390 | ||
391 | p = oentries; | |
392 | do | |
393 | { | |
e0f3df8f | 394 | PTR x = *p; |
eb383413 | 395 | |
b4fe2683 JM |
396 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) |
397 | { | |
e0f3df8f | 398 | PTR *q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x)); |
eb383413 | 399 | |
b4fe2683 JM |
400 | *q = x; |
401 | } | |
eb383413 | 402 | |
b4fe2683 JM |
403 | p++; |
404 | } | |
405 | while (p < olimit); | |
eb383413 | 406 | |
18893690 DD |
407 | if (htab->free_f != NULL) |
408 | (*htab->free_f) (oentries); | |
5f9624e3 DJ |
409 | else if (htab->free_with_arg_f != NULL) |
410 | (*htab->free_with_arg_f) (htab->alloc_arg, oentries); | |
99a4c1bd | 411 | return 1; |
e2eaf477 ILT |
412 | } |
413 | ||
b4fe2683 JM |
414 | /* This function searches for a hash table entry equal to the given |
415 | element. It cannot be used to insert or delete an element. */ | |
416 | ||
e0f3df8f | 417 | PTR |
b4fe2683 JM |
418 | htab_find_with_hash (htab, element, hash) |
419 | htab_t htab; | |
e0f3df8f | 420 | const PTR element; |
eb383413 | 421 | hashval_t hash; |
e2eaf477 | 422 | { |
eb383413 L |
423 | unsigned int index; |
424 | hashval_t hash2; | |
b4fe2683 | 425 | size_t size; |
e0f3df8f | 426 | PTR entry; |
e2eaf477 | 427 | |
b4fe2683 JM |
428 | htab->searches++; |
429 | size = htab->size; | |
b4fe2683 JM |
430 | index = hash % size; |
431 | ||
eb383413 L |
432 | entry = htab->entries[index]; |
433 | if (entry == EMPTY_ENTRY | |
434 | || (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
435 | return entry; | |
436 | ||
437 | hash2 = 1 + hash % (size - 2); | |
438 | ||
b4fe2683 | 439 | for (;;) |
e2eaf477 | 440 | { |
b4fe2683 JM |
441 | htab->collisions++; |
442 | index += hash2; | |
443 | if (index >= size) | |
444 | index -= size; | |
eb383413 L |
445 | |
446 | entry = htab->entries[index]; | |
447 | if (entry == EMPTY_ENTRY | |
448 | || (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
449 | return entry; | |
e2eaf477 | 450 | } |
b4fe2683 JM |
451 | } |
452 | ||
453 | /* Like htab_find_slot_with_hash, but compute the hash value from the | |
454 | element. */ | |
eb383413 | 455 | |
e0f3df8f | 456 | PTR |
b4fe2683 JM |
457 | htab_find (htab, element) |
458 | htab_t htab; | |
e0f3df8f | 459 | const PTR element; |
b4fe2683 JM |
460 | { |
461 | return htab_find_with_hash (htab, element, (*htab->hash_f) (element)); | |
462 | } | |
463 | ||
464 | /* This function searches for a hash table slot containing an entry | |
465 | equal to the given element. To delete an entry, call this with | |
466 | INSERT = 0, then call htab_clear_slot on the slot returned (possibly | |
467 | after doing some checks). To insert an entry, call this with | |
99a4c1bd HPN |
468 | INSERT = 1, then write the value you want into the returned slot. |
469 | When inserting an entry, NULL may be returned if memory allocation | |
470 | fails. */ | |
b4fe2683 | 471 | |
e0f3df8f | 472 | PTR * |
b4fe2683 JM |
473 | htab_find_slot_with_hash (htab, element, hash, insert) |
474 | htab_t htab; | |
e0f3df8f | 475 | const PTR element; |
eb383413 L |
476 | hashval_t hash; |
477 | enum insert_option insert; | |
b4fe2683 | 478 | { |
e0f3df8f | 479 | PTR *first_deleted_slot; |
eb383413 L |
480 | unsigned int index; |
481 | hashval_t hash2; | |
b4fe2683 | 482 | size_t size; |
b1c933fc | 483 | PTR entry; |
b4fe2683 | 484 | |
99a4c1bd HPN |
485 | if (insert == INSERT && htab->size * 3 <= htab->n_elements * 4 |
486 | && htab_expand (htab) == 0) | |
487 | return NULL; | |
b4fe2683 JM |
488 | |
489 | size = htab->size; | |
b4fe2683 JM |
490 | index = hash % size; |
491 | ||
e2eaf477 | 492 | htab->searches++; |
b4fe2683 JM |
493 | first_deleted_slot = NULL; |
494 | ||
b1c933fc RH |
495 | entry = htab->entries[index]; |
496 | if (entry == EMPTY_ENTRY) | |
497 | goto empty_entry; | |
498 | else if (entry == DELETED_ENTRY) | |
499 | first_deleted_slot = &htab->entries[index]; | |
500 | else if ((*htab->eq_f) (entry, element)) | |
501 | return &htab->entries[index]; | |
502 | ||
503 | hash2 = 1 + hash % (size - 2); | |
b4fe2683 | 504 | for (;;) |
e2eaf477 | 505 | { |
b1c933fc RH |
506 | htab->collisions++; |
507 | index += hash2; | |
508 | if (index >= size) | |
509 | index -= size; | |
510 | ||
511 | entry = htab->entries[index]; | |
b4fe2683 | 512 | if (entry == EMPTY_ENTRY) |
b1c933fc RH |
513 | goto empty_entry; |
514 | else if (entry == DELETED_ENTRY) | |
b4fe2683 JM |
515 | { |
516 | if (!first_deleted_slot) | |
517 | first_deleted_slot = &htab->entries[index]; | |
518 | } | |
b1c933fc | 519 | else if ((*htab->eq_f) (entry, element)) |
eb383413 | 520 | return &htab->entries[index]; |
e2eaf477 | 521 | } |
b1c933fc RH |
522 | |
523 | empty_entry: | |
524 | if (insert == NO_INSERT) | |
525 | return NULL; | |
526 | ||
527 | htab->n_elements++; | |
528 | ||
529 | if (first_deleted_slot) | |
530 | { | |
531 | *first_deleted_slot = EMPTY_ENTRY; | |
532 | return first_deleted_slot; | |
533 | } | |
534 | ||
535 | return &htab->entries[index]; | |
e2eaf477 ILT |
536 | } |
537 | ||
b4fe2683 JM |
538 | /* Like htab_find_slot_with_hash, but compute the hash value from the |
539 | element. */ | |
eb383413 | 540 | |
e0f3df8f | 541 | PTR * |
b4fe2683 JM |
542 | htab_find_slot (htab, element, insert) |
543 | htab_t htab; | |
e0f3df8f | 544 | const PTR element; |
eb383413 | 545 | enum insert_option insert; |
b4fe2683 JM |
546 | { |
547 | return htab_find_slot_with_hash (htab, element, (*htab->hash_f) (element), | |
548 | insert); | |
549 | } | |
550 | ||
551 | /* This function deletes an element with the given value from hash | |
552 | table. If there is no matching element in the hash table, this | |
553 | function does nothing. */ | |
e2eaf477 ILT |
554 | |
555 | void | |
b4fe2683 JM |
556 | htab_remove_elt (htab, element) |
557 | htab_t htab; | |
e0f3df8f | 558 | PTR element; |
e2eaf477 | 559 | { |
e0f3df8f | 560 | PTR *slot; |
b4fe2683 | 561 | |
eb383413 | 562 | slot = htab_find_slot (htab, element, NO_INSERT); |
b4fe2683 JM |
563 | if (*slot == EMPTY_ENTRY) |
564 | return; | |
565 | ||
566 | if (htab->del_f) | |
567 | (*htab->del_f) (*slot); | |
e2eaf477 | 568 | |
b4fe2683 JM |
569 | *slot = DELETED_ENTRY; |
570 | htab->n_deleted++; | |
e2eaf477 ILT |
571 | } |
572 | ||
b4fe2683 JM |
573 | /* This function clears a specified slot in a hash table. It is |
574 | useful when you've already done the lookup and don't want to do it | |
575 | again. */ | |
e2eaf477 ILT |
576 | |
577 | void | |
b4fe2683 JM |
578 | htab_clear_slot (htab, slot) |
579 | htab_t htab; | |
e0f3df8f | 580 | PTR *slot; |
e2eaf477 ILT |
581 | { |
582 | if (slot < htab->entries || slot >= htab->entries + htab->size | |
583 | || *slot == EMPTY_ENTRY || *slot == DELETED_ENTRY) | |
584 | abort (); | |
eb383413 | 585 | |
b4fe2683 JM |
586 | if (htab->del_f) |
587 | (*htab->del_f) (*slot); | |
eb383413 | 588 | |
e2eaf477 | 589 | *slot = DELETED_ENTRY; |
b4fe2683 | 590 | htab->n_deleted++; |
e2eaf477 ILT |
591 | } |
592 | ||
593 | /* This function scans over the entire hash table calling | |
594 | CALLBACK for each live entry. If CALLBACK returns false, | |
595 | the iteration stops. INFO is passed as CALLBACK's second | |
596 | argument. */ | |
597 | ||
598 | void | |
b4fe2683 JM |
599 | htab_traverse (htab, callback, info) |
600 | htab_t htab; | |
601 | htab_trav callback; | |
e0f3df8f | 602 | PTR info; |
e2eaf477 | 603 | { |
e0f3df8f HPN |
604 | PTR *slot = htab->entries; |
605 | PTR *limit = slot + htab->size; | |
eb383413 | 606 | |
b4fe2683 JM |
607 | do |
608 | { | |
e0f3df8f | 609 | PTR x = *slot; |
eb383413 | 610 | |
b4fe2683 JM |
611 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) |
612 | if (!(*callback) (slot, info)) | |
613 | break; | |
614 | } | |
615 | while (++slot < limit); | |
e2eaf477 ILT |
616 | } |
617 | ||
eb383413 | 618 | /* Return the current size of given hash table. */ |
e2eaf477 ILT |
619 | |
620 | size_t | |
b4fe2683 JM |
621 | htab_size (htab) |
622 | htab_t htab; | |
e2eaf477 ILT |
623 | { |
624 | return htab->size; | |
625 | } | |
626 | ||
eb383413 | 627 | /* Return the current number of elements in given hash table. */ |
e2eaf477 ILT |
628 | |
629 | size_t | |
b4fe2683 JM |
630 | htab_elements (htab) |
631 | htab_t htab; | |
e2eaf477 | 632 | { |
b4fe2683 | 633 | return htab->n_elements - htab->n_deleted; |
e2eaf477 ILT |
634 | } |
635 | ||
eb383413 L |
636 | /* Return the fraction of fixed collisions during all work with given |
637 | hash table. */ | |
e2eaf477 | 638 | |
b4fe2683 JM |
639 | double |
640 | htab_collisions (htab) | |
641 | htab_t htab; | |
e2eaf477 | 642 | { |
eb383413 | 643 | if (htab->searches == 0) |
b4fe2683 | 644 | return 0.0; |
eb383413 L |
645 | |
646 | return (double) htab->collisions / (double) htab->searches; | |
e2eaf477 | 647 | } |
8fc34799 | 648 | |
68a41de7 DD |
649 | /* Hash P as a null-terminated string. |
650 | ||
651 | Copied from gcc/hashtable.c. Zack had the following to say with respect | |
652 | to applicability, though note that unlike hashtable.c, this hash table | |
653 | implementation re-hashes rather than chain buckets. | |
654 | ||
655 | http://gcc.gnu.org/ml/gcc-patches/2001-08/msg01021.html | |
656 | From: Zack Weinberg <zackw@panix.com> | |
657 | Date: Fri, 17 Aug 2001 02:15:56 -0400 | |
658 | ||
659 | I got it by extracting all the identifiers from all the source code | |
660 | I had lying around in mid-1999, and testing many recurrences of | |
661 | the form "H_n = H_{n-1} * K + c_n * L + M" where K, L, M were either | |
662 | prime numbers or the appropriate identity. This was the best one. | |
663 | I don't remember exactly what constituted "best", except I was | |
664 | looking at bucket-length distributions mostly. | |
665 | ||
666 | So it should be very good at hashing identifiers, but might not be | |
667 | as good at arbitrary strings. | |
668 | ||
669 | I'll add that it thoroughly trounces the hash functions recommended | |
670 | for this use at http://burtleburtle.net/bob/hash/index.html, both | |
671 | on speed and bucket distribution. I haven't tried it against the | |
672 | function they just started using for Perl's hashes. */ | |
8fc34799 DD |
673 | |
674 | hashval_t | |
675 | htab_hash_string (p) | |
676 | const PTR p; | |
677 | { | |
678 | const unsigned char *str = (const unsigned char *) p; | |
679 | hashval_t r = 0; | |
680 | unsigned char c; | |
681 | ||
682 | while ((c = *str++) != 0) | |
683 | r = r * 67 + c - 113; | |
684 | ||
685 | return r; | |
686 | } |