1 /* Implementation of the hash table lisp object type.
2 Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
3 Copyright (C) 1995, 1996 Ben Wing.
4 Copyright (C) 1997 Free Software Foundation, Inc.
6 This file is part of XEmacs.
8 XEmacs is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by the
10 Free Software Foundation; either version 2, or (at your option) any
13 XEmacs is distributed in the hope that it will be useful, but WITHOUT
14 ANY WARRANTY; without even the implied warranty of MERCNTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with XEmacs; see the file COPYING. If not, write to
20 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
23 /* Synched up with: Not in FSF. */
30 Lisp_Object Qhash_tablep;
31 static Lisp_Object Qhashtable, Qhash_table;
32 static Lisp_Object Qweakness, Qvalue;
33 static Lisp_Object Vall_weak_hash_tables;
34 static Lisp_Object Qrehash_size, Qrehash_threshold;
35 static Lisp_Object Q_size, Q_test, Q_weakness, Q_rehash_size, Q_rehash_threshold;
37 /* obsolete as of 19990901 in xemacs-21.2 */
38 static Lisp_Object Qweak, Qkey_weak, Qvalue_weak, Qnon_weak, Q_type;
46 struct Lisp_Hash_Table
48 struct lcrecord_header header;
53 double rehash_threshold;
55 hash_table_hash_function_t hash_function;
56 hash_table_test_function_t test_function;
58 enum hash_table_weakness weakness;
59 Lisp_Object next_weak; /* Used to chain together all of the weak
60 hash tables. Don't mark through this. */
62 typedef struct Lisp_Hash_Table Lisp_Hash_Table;
64 #define HENTRY_CLEAR_P(hentry) ((*(EMACS_UINT*)(&((hentry)->key))) == 0)
65 #define CLEAR_HENTRY(hentry) \
66 ((*(EMACS_UINT*)(&((hentry)->key))) = 0, \
67 (*(EMACS_UINT*)(&((hentry)->value))) = 0)
69 #define HASH_TABLE_DEFAULT_SIZE 16
70 #define HASH_TABLE_DEFAULT_REHASH_SIZE 1.3
71 #define HASH_TABLE_MIN_SIZE 10
73 #define HASH_CODE(key, ht) \
74 (((((ht)->hash_function ? (ht)->hash_function (key) : LISP_HASH (key)) \
75 * (ht)->golden_ratio) \
78 #define KEYS_EQUAL_P(key1, key2, testfun) \
79 (EQ ((key1), (key2)) || ((testfun) && (testfun) ((key1), (key2))))
81 #define LINEAR_PROBING_LOOP(probe, entries, size) \
83 !HENTRY_CLEAR_P (probe) || \
84 (probe == entries + size ? \
85 (probe = entries, !HENTRY_CLEAR_P (probe)) : 0); \
88 #ifndef ERROR_CHECK_HASH_TABLE
89 # ifdef ERROR_CHECK_TYPECHECK
90 # define ERROR_CHECK_HASH_TABLE 1
92 # define ERROR_CHECK_HASH_TABLE 0
96 #if ERROR_CHECK_HASH_TABLE
98 check_hash_table_invariants (Lisp_Hash_Table *ht)
100 assert (ht->count < ht->size);
101 assert (ht->count <= ht->rehash_count);
102 assert (ht->rehash_count < ht->size);
103 assert ((double) ht->count * ht->rehash_threshold - 1 <= (double) ht->rehash_count);
104 assert (HENTRY_CLEAR_P (ht->hentries + ht->size));
107 #define check_hash_table_invariants(ht)
110 /* We use linear probing instead of double hashing, despite its lack
111 of blessing by Knuth and company, because, as a result of the
112 increasing discrepancy between CPU speeds and memory speeds, cache
113 behavior is becoming increasingly important, e.g:
115 For a trivial loop, the penalty for non-sequential access of an array is:
116 - a factor of 3-4 on Pentium Pro 200 Mhz
117 - a factor of 10 on Ultrasparc 300 Mhz */
119 /* Return a suitable size for a hash table, with at least SIZE slots. */
121 hash_table_size (size_t requested_size)
123 /* Return some prime near, but greater than or equal to, SIZE.
124 Decades from the time of writing, someone will have a system large
125 enough that the list below will be too short... */
126 static CONST size_t primes [] =
128 19, 29, 41, 59, 79, 107, 149, 197, 263, 347, 457, 599, 787, 1031,
129 1361, 1777, 2333, 3037, 3967, 5167, 6719, 8737, 11369, 14783,
130 19219, 24989, 32491, 42257, 54941, 71429, 92861, 120721, 156941,
131 204047, 265271, 344857, 448321, 582821, 757693, 985003, 1280519,
132 1664681, 2164111, 2813353, 3657361, 4754591, 6180989, 8035301,
133 10445899, 13579681, 17653589, 22949669, 29834603, 38784989,
134 50420551, 65546729, 85210757, 110774011, 144006217, 187208107,
135 243370577, 316381771, 411296309, 534685237, 695090819, 903618083,
136 1174703521, 1527114613, 1985248999, 2580823717UL, 3355070839UL
138 /* We've heard of binary search. */
140 for (low = 0, high = countof (primes) - 1; high - low > 1;)
142 /* Loop Invariant: size < primes [high] */
143 int mid = (low + high) / 2;
144 if (primes [mid] < requested_size)
149 return primes [high];
153 #if 0 /* I don't think these are needed any more.
154 If using the general lisp_object_equal_*() functions
155 causes efficiency problems, these can be resurrected. --ben */
156 /* equality and hash functions for Lisp strings */
158 lisp_string_equal (Lisp_Object str1, Lisp_Object str2)
160 /* This is wrong anyway. You can't use strcmp() on Lisp strings,
161 because they can contain zero characters. */
162 return !strcmp ((char *) XSTRING_DATA (str1), (char *) XSTRING_DATA (str2));
166 lisp_string_hash (Lisp_Object obj)
168 return hash_string (XSTRING_DATA (str), XSTRING_LENGTH (str));
174 lisp_object_eql_equal (Lisp_Object obj1, Lisp_Object obj2)
176 return EQ (obj1, obj2) || (FLOATP (obj1) && internal_equal (obj1, obj2, 0));
180 lisp_object_eql_hash (Lisp_Object obj)
182 return FLOATP (obj) ? internal_hash (obj, 0) : LISP_HASH (obj);
186 lisp_object_equal_equal (Lisp_Object obj1, Lisp_Object obj2)
188 return internal_equal (obj1, obj2, 0);
192 lisp_object_equal_hash (Lisp_Object obj)
194 return internal_hash (obj, 0);
199 mark_hash_table (Lisp_Object obj)
201 Lisp_Hash_Table *ht = XHASH_TABLE (obj);
203 /* If the hash table is weak, we don't want to mark the keys and
204 values (we scan over them after everything else has been marked,
205 and mark or remove them as necessary). */
206 if (ht->weakness == HASH_TABLE_NON_WEAK)
208 hentry *e, *sentinel;
210 for (e = ht->hentries, sentinel = e + ht->size; e < sentinel; e++)
211 if (!HENTRY_CLEAR_P (e))
213 mark_object (e->key);
214 mark_object (e->value);
220 /* Equality of hash tables. Two hash tables are equal when they are of
221 the same weakness and test function, they have the same number of
222 elements, and for each key in the hash table, the values are `equal'.
224 This is similar to Common Lisp `equalp' of hash tables, with the
225 difference that CL requires the keys to be compared with the test
226 function, which we don't do. Doing that would require consing, and
227 consing is a bad idea in `equal'. Anyway, our method should provide
228 the same result -- if the keys are not equal according to the test
229 function, then Fgethash() in hash_table_equal_mapper() will fail. */
231 hash_table_equal (Lisp_Object hash_table1, Lisp_Object hash_table2, int depth)
233 Lisp_Hash_Table *ht1 = XHASH_TABLE (hash_table1);
234 Lisp_Hash_Table *ht2 = XHASH_TABLE (hash_table2);
235 hentry *e, *sentinel;
237 if ((ht1->test_function != ht2->test_function) ||
238 (ht1->weakness != ht2->weakness) ||
239 (ht1->count != ht2->count))
244 for (e = ht1->hentries, sentinel = e + ht1->size; e < sentinel; e++)
245 if (!HENTRY_CLEAR_P (e))
246 /* Look up the key in the other hash table, and compare the values. */
248 Lisp_Object value_in_other = Fgethash (e->key, hash_table2, Qunbound);
249 if (UNBOUNDP (value_in_other) ||
250 !internal_equal (e->value, value_in_other, depth))
251 return 0; /* Give up */
257 /* Printing hash tables.
259 This is non-trivial, because we use a readable structure-style
260 syntax for hash tables. This means that a typical hash table will be
261 readably printed in the form of:
263 #s(hash-table size 2 data (key1 value1 key2 value2))
265 The supported hash table structure keywords and their values are:
266 `test' (eql (or nil), eq or equal)
267 `size' (a natnum or nil)
268 `rehash-size' (a float)
269 `rehash-threshold' (a float)
270 `weakness' (nil, t, key or value)
273 If `print-readably' is non-nil, then a simpler syntax is used; for
276 #<hash-table size 2/13 data (key1 value1 key2 value2) 0x874d>
278 The data is truncated to four pairs, and the rest is shown with
279 `...'. This printer does not cons. */
282 /* Print the data of the hash table. This maps through a Lisp
283 hash table and prints key/value pairs using PRINTCHARFUN. */
285 print_hash_table_data (Lisp_Hash_Table *ht, Lisp_Object printcharfun)
288 hentry *e, *sentinel;
290 write_c_string (" data (", printcharfun);
292 for (e = ht->hentries, sentinel = e + ht->size; e < sentinel; e++)
293 if (!HENTRY_CLEAR_P (e))
296 write_c_string (" ", printcharfun);
297 if (!print_readably && count > 3)
299 write_c_string ("...", printcharfun);
302 print_internal (e->key, printcharfun, 1);
303 write_c_string (" ", printcharfun);
304 print_internal (e->value, printcharfun, 1);
308 write_c_string (")", printcharfun);
312 print_hash_table (Lisp_Object obj, Lisp_Object printcharfun, int escapeflag)
314 Lisp_Hash_Table *ht = XHASH_TABLE (obj);
317 write_c_string (print_readably ? "#s(hash-table" : "#<hash-table",
320 /* These checks have a kludgy look to them, but they are safe.
321 Due to nature of hashing, you cannot use arbitrary
322 test functions anyway. */
323 if (!ht->test_function)
324 write_c_string (" test eq", printcharfun);
325 else if (ht->test_function == lisp_object_equal_equal)
326 write_c_string (" test equal", printcharfun);
327 else if (ht->test_function == lisp_object_eql_equal)
332 if (ht->count || !print_readably)
335 sprintf (buf, " size %lu", (unsigned long) ht->count);
337 sprintf (buf, " size %lu/%lu",
338 (unsigned long) ht->count,
339 (unsigned long) ht->size);
340 write_c_string (buf, printcharfun);
343 if (ht->weakness != HASH_TABLE_NON_WEAK)
345 sprintf (buf, " weakness %s",
346 (ht->weakness == HASH_TABLE_WEAK ? "t" :
347 ht->weakness == HASH_TABLE_KEY_WEAK ? "key" :
348 ht->weakness == HASH_TABLE_VALUE_WEAK ? "value" :
349 "you-d-better-not-see-this"));
350 write_c_string (buf, printcharfun);
354 print_hash_table_data (ht, printcharfun);
357 write_c_string (")", printcharfun);
360 sprintf (buf, " 0x%x>", ht->header.uid);
361 write_c_string (buf, printcharfun);
366 finalize_hash_table (void *header, int for_disksave)
370 Lisp_Hash_Table *ht = (Lisp_Hash_Table *) header;
372 xfree (ht->hentries);
377 static const struct lrecord_description hentry_description_1[] = {
378 { XD_LISP_OBJECT, offsetof(hentry, key), 2 },
382 static const struct struct_description hentry_description = {
387 const struct lrecord_description hash_table_description[] = {
388 { XD_SIZE_T, offsetof(Lisp_Hash_Table, size) },
389 { XD_STRUCT_PTR, offsetof(Lisp_Hash_Table, hentries), XD_INDIRECT(0, 1), &hentry_description },
390 { XD_LO_LINK, offsetof(Lisp_Hash_Table, next_weak) },
394 DEFINE_LRECORD_IMPLEMENTATION ("hash-table", hash_table,
395 mark_hash_table, print_hash_table,
397 /* #### Implement hash_table_hash()! */
399 hash_table_description,
402 static Lisp_Hash_Table *
403 xhash_table (Lisp_Object hash_table)
406 CHECK_HASH_TABLE (hash_table);
407 check_hash_table_invariants (XHASH_TABLE (hash_table));
408 return XHASH_TABLE (hash_table);
412 /************************************************************************/
413 /* Creation of Hash Tables */
414 /************************************************************************/
416 /* Creation of hash tables, without error-checking. */
418 hash_table_rehash_threshold (Lisp_Hash_Table *ht)
421 ht->rehash_threshold > 0.0 ? ht->rehash_threshold :
422 ht->size > 4096 && !ht->test_function ? 0.7 : 0.6;
426 compute_hash_table_derived_values (Lisp_Hash_Table *ht)
428 ht->rehash_count = (size_t)
429 ((double) ht->size * hash_table_rehash_threshold (ht));
430 ht->golden_ratio = (size_t)
431 ((double) ht->size * (.6180339887 / (double) sizeof (Lisp_Object)));
435 make_general_lisp_hash_table (enum hash_table_test test,
438 double rehash_threshold,
439 enum hash_table_weakness weakness)
441 Lisp_Object hash_table;
442 Lisp_Hash_Table *ht = alloc_lcrecord_type (Lisp_Hash_Table, &lrecord_hash_table);
444 ht->rehash_size = rehash_size;
445 ht->rehash_threshold = rehash_threshold;
446 ht->weakness = weakness;
451 ht->test_function = 0;
452 ht->hash_function = 0;
456 ht->test_function = lisp_object_eql_equal;
457 ht->hash_function = lisp_object_eql_hash;
460 case HASH_TABLE_EQUAL:
461 ht->test_function = lisp_object_equal_equal;
462 ht->hash_function = lisp_object_equal_hash;
469 if (ht->rehash_size <= 0.0)
470 ht->rehash_size = HASH_TABLE_DEFAULT_REHASH_SIZE;
471 if (size < HASH_TABLE_MIN_SIZE)
472 size = HASH_TABLE_MIN_SIZE;
473 if (rehash_threshold < 0.0)
474 rehash_threshold = 0.75;
476 hash_table_size ((size_t) ((double) size / hash_table_rehash_threshold (ht)) + 1);
478 compute_hash_table_derived_values (ht);
480 /* We leave room for one never-occupied sentinel hentry at the end. */
481 ht->hentries = xnew_array (hentry, ht->size + 1);
484 hentry *e, *sentinel;
485 for (e = ht->hentries, sentinel = e + ht->size; e <= sentinel; e++)
489 XSETHASH_TABLE (hash_table, ht);
491 if (weakness == HASH_TABLE_NON_WEAK)
492 ht->next_weak = Qunbound;
494 ht->next_weak = Vall_weak_hash_tables, Vall_weak_hash_tables = hash_table;
500 make_lisp_hash_table (size_t size,
501 enum hash_table_weakness weakness,
502 enum hash_table_test test)
504 return make_general_lisp_hash_table
505 (test, size, HASH_TABLE_DEFAULT_REHASH_SIZE, -1.0, weakness);
508 /* Pretty reading of hash tables.
510 Here we use the existing structures mechanism (which is,
511 unfortunately, pretty cumbersome) for validating and instantiating
512 the hash tables. The idea is that the side-effect of reading a
513 #s(hash-table PLIST) object is creation of a hash table with desired
514 properties, and that the hash table is returned. */
516 /* Validation functions: each keyword provides its own validation
517 function. The errors should maybe be continuable, but it is
518 unclear how this would cope with ERRB. */
520 hash_table_size_validate (Lisp_Object keyword, Lisp_Object value,
526 maybe_signal_error (Qwrong_type_argument, list2 (Qnatnump, value),
532 decode_hash_table_size (Lisp_Object obj)
534 return NILP (obj) ? HASH_TABLE_DEFAULT_SIZE : XINT (obj);
538 hash_table_weakness_validate (Lisp_Object keyword, Lisp_Object value,
541 if (EQ (value, Qnil)) return 1;
542 if (EQ (value, Qt)) return 1;
543 if (EQ (value, Qkey)) return 1;
544 if (EQ (value, Qvalue)) return 1;
546 /* Following values are obsolete as of 19990901 in xemacs-21.2 */
547 if (EQ (value, Qnon_weak)) return 1;
548 if (EQ (value, Qweak)) return 1;
549 if (EQ (value, Qkey_weak)) return 1;
550 if (EQ (value, Qvalue_weak)) return 1;
552 maybe_signal_simple_error ("Invalid hash table weakness",
553 value, Qhash_table, errb);
557 static enum hash_table_weakness
558 decode_hash_table_weakness (Lisp_Object obj)
560 if (EQ (obj, Qnil)) return HASH_TABLE_NON_WEAK;
561 if (EQ (obj, Qt)) return HASH_TABLE_WEAK;
562 if (EQ (obj, Qkey)) return HASH_TABLE_KEY_WEAK;
563 if (EQ (obj, Qvalue)) return HASH_TABLE_VALUE_WEAK;
565 /* Following values are obsolete as of 19990901 in xemacs-21.2 */
566 if (EQ (obj, Qnon_weak)) return HASH_TABLE_NON_WEAK;
567 if (EQ (obj, Qweak)) return HASH_TABLE_WEAK;
568 if (EQ (obj, Qkey_weak)) return HASH_TABLE_KEY_WEAK;
569 if (EQ (obj, Qvalue_weak)) return HASH_TABLE_VALUE_WEAK;
571 signal_simple_error ("Invalid hash table weakness", obj);
572 return HASH_TABLE_NON_WEAK; /* not reached */
576 hash_table_test_validate (Lisp_Object keyword, Lisp_Object value,
579 if (EQ (value, Qnil)) return 1;
580 if (EQ (value, Qeq)) return 1;
581 if (EQ (value, Qequal)) return 1;
582 if (EQ (value, Qeql)) return 1;
584 maybe_signal_simple_error ("Invalid hash table test",
585 value, Qhash_table, errb);
589 static enum hash_table_test
590 decode_hash_table_test (Lisp_Object obj)
592 if (EQ (obj, Qnil)) return HASH_TABLE_EQL;
593 if (EQ (obj, Qeq)) return HASH_TABLE_EQ;
594 if (EQ (obj, Qequal)) return HASH_TABLE_EQUAL;
595 if (EQ (obj, Qeql)) return HASH_TABLE_EQL;
597 signal_simple_error ("Invalid hash table test", obj);
598 return HASH_TABLE_EQ; /* not reached */
602 hash_table_rehash_size_validate (Lisp_Object keyword, Lisp_Object value,
607 maybe_signal_error (Qwrong_type_argument, list2 (Qfloatp, value),
613 double rehash_size = XFLOAT_DATA (value);
614 if (rehash_size <= 1.0)
616 maybe_signal_simple_error
617 ("Hash table rehash size must be greater than 1.0",
618 value, Qhash_table, errb);
627 decode_hash_table_rehash_size (Lisp_Object rehash_size)
629 return NILP (rehash_size) ? -1.0 : XFLOAT_DATA (rehash_size);
633 hash_table_rehash_threshold_validate (Lisp_Object keyword, Lisp_Object value,
638 maybe_signal_error (Qwrong_type_argument, list2 (Qfloatp, value),
644 double rehash_threshold = XFLOAT_DATA (value);
645 if (rehash_threshold <= 0.0 || rehash_threshold >= 1.0)
647 maybe_signal_simple_error
648 ("Hash table rehash threshold must be between 0.0 and 1.0",
649 value, Qhash_table, errb);
658 decode_hash_table_rehash_threshold (Lisp_Object rehash_threshold)
660 return NILP (rehash_threshold) ? -1.0 : XFLOAT_DATA (rehash_threshold);
664 hash_table_data_validate (Lisp_Object keyword, Lisp_Object value,
669 GET_EXTERNAL_LIST_LENGTH (value, len);
673 maybe_signal_simple_error
674 ("Hash table data must have alternating key/value pairs",
675 value, Qhash_table, errb);
681 /* The actual instantiation of a hash table. This does practically no
682 error checking, because it relies on the fact that the paranoid
683 functions above have error-checked everything to the last details.
684 If this assumption is wrong, we will get a crash immediately (with
685 error-checking compiled in), and we'll know if there is a bug in
686 the structure mechanism. So there. */
688 hash_table_instantiate (Lisp_Object plist)
690 Lisp_Object hash_table;
691 Lisp_Object test = Qnil;
692 Lisp_Object size = Qnil;
693 Lisp_Object rehash_size = Qnil;
694 Lisp_Object rehash_threshold = Qnil;
695 Lisp_Object weakness = Qnil;
696 Lisp_Object data = Qnil;
698 while (!NILP (plist))
700 Lisp_Object key, value;
701 key = XCAR (plist); plist = XCDR (plist);
702 value = XCAR (plist); plist = XCDR (plist);
704 if (EQ (key, Qtest)) test = value;
705 else if (EQ (key, Qsize)) size = value;
706 else if (EQ (key, Qrehash_size)) rehash_size = value;
707 else if (EQ (key, Qrehash_threshold)) rehash_threshold = value;
708 else if (EQ (key, Qweakness)) weakness = value;
709 else if (EQ (key, Qdata)) data = value;
710 else if (EQ (key, Qtype))/*obsolete*/ weakness = value;
715 /* Create the hash table. */
716 hash_table = make_general_lisp_hash_table
717 (decode_hash_table_test (test),
718 decode_hash_table_size (size),
719 decode_hash_table_rehash_size (rehash_size),
720 decode_hash_table_rehash_threshold (rehash_threshold),
721 decode_hash_table_weakness (weakness));
723 /* I'm not sure whether this can GC, but better safe than sorry. */
728 /* And fill it with data. */
731 Lisp_Object key, value;
732 key = XCAR (data); data = XCDR (data);
733 value = XCAR (data); data = XCDR (data);
734 Fputhash (key, value, hash_table);
743 structure_type_create_hash_table_structure_name (Lisp_Object structure_name)
745 struct structure_type *st;
747 st = define_structure_type (structure_name, 0, hash_table_instantiate);
748 define_structure_type_keyword (st, Qtest, hash_table_test_validate);
749 define_structure_type_keyword (st, Qsize, hash_table_size_validate);
750 define_structure_type_keyword (st, Qrehash_size, hash_table_rehash_size_validate);
751 define_structure_type_keyword (st, Qrehash_threshold, hash_table_rehash_threshold_validate);
752 define_structure_type_keyword (st, Qweakness, hash_table_weakness_validate);
753 define_structure_type_keyword (st, Qdata, hash_table_data_validate);
755 /* obsolete as of 19990901 in xemacs-21.2 */
756 define_structure_type_keyword (st, Qtype, hash_table_weakness_validate);
759 /* Create a built-in Lisp structure type named `hash-table'.
760 We make #s(hashtable ...) equivalent to #s(hash-table ...),
761 for backward compatibility.
762 This is called from emacs.c. */
764 structure_type_create_hash_table (void)
766 structure_type_create_hash_table_structure_name (Qhash_table);
767 structure_type_create_hash_table_structure_name (Qhashtable); /* compat */
771 /************************************************************************/
772 /* Definition of Lisp-visible methods */
773 /************************************************************************/
775 DEFUN ("hash-table-p", Fhash_table_p, 1, 1, 0, /*
776 Return t if OBJECT is a hash table, else nil.
780 return HASH_TABLEP (object) ? Qt : Qnil;
783 DEFUN ("make-hash-table", Fmake_hash_table, 0, MANY, 0, /*
784 Return a new empty hash table object.
785 Use Common Lisp style keywords to specify hash table properties.
786 (make-hash-table &key test size rehash-size rehash-threshold weakness)
788 Keyword :test can be `eq', `eql' (default) or `equal'.
789 Comparison between keys is done using this function.
790 If speed is important, consider using `eq'.
791 When storing strings in the hash table, you will likely need to use `equal'.
793 Keyword :size specifies the number of keys likely to be inserted.
794 This number of entries can be inserted without enlarging the hash table.
796 Keyword :rehash-size must be a float greater than 1.0, and specifies
797 the factor by which to increase the size of the hash table when enlarging.
799 Keyword :rehash-threshold must be a float between 0.0 and 1.0,
800 and specifies the load factor of the hash table which triggers enlarging.
802 Non-standard keyword :weakness can be `nil' (default), `t', `key' or `value'.
804 A weak hash table is one whose pointers do not count as GC referents:
805 for any key-value pair in the hash table, if the only remaining pointer
806 to either the key or the value is in a weak hash table, then the pair
807 will be removed from the hash table, and the key and value collected.
808 A non-weak hash table (or any other pointer) would prevent the object
809 from being collected.
811 A key-weak hash table is similar to a fully-weak hash table except that
812 a key-value pair will be removed only if the key remains unmarked
813 outside of weak hash tables. The pair will remain in the hash table if
814 the key is pointed to by something other than a weak hash table, even
817 A value-weak hash table is similar to a fully-weak hash table except
818 that a key-value pair will be removed only if the value remains
819 unmarked outside of weak hash tables. The pair will remain in the
820 hash table if the value is pointed to by something other than a weak
821 hash table, even if the key is not.
823 (int nargs, Lisp_Object *args))
826 Lisp_Object test = Qnil;
827 Lisp_Object size = Qnil;
828 Lisp_Object rehash_size = Qnil;
829 Lisp_Object rehash_threshold = Qnil;
830 Lisp_Object weakness = Qnil;
832 while (i + 1 < nargs)
834 Lisp_Object keyword = args[i++];
835 Lisp_Object value = args[i++];
837 if (EQ (keyword, Q_test)) test = value;
838 else if (EQ (keyword, Q_size)) size = value;
839 else if (EQ (keyword, Q_rehash_size)) rehash_size = value;
840 else if (EQ (keyword, Q_rehash_threshold)) rehash_threshold = value;
841 else if (EQ (keyword, Q_weakness)) weakness = value;
842 else if (EQ (keyword, Q_type))/*obsolete*/ weakness = value;
843 else signal_simple_error ("Invalid hash table property keyword", keyword);
847 signal_simple_error ("Hash table property requires a value", args[i]);
849 #define VALIDATE_VAR(var) \
850 if (!NILP (var)) hash_table_##var##_validate (Q##var, var, ERROR_ME);
854 VALIDATE_VAR (rehash_size);
855 VALIDATE_VAR (rehash_threshold);
856 VALIDATE_VAR (weakness);
858 return make_general_lisp_hash_table
859 (decode_hash_table_test (test),
860 decode_hash_table_size (size),
861 decode_hash_table_rehash_size (rehash_size),
862 decode_hash_table_rehash_threshold (rehash_threshold),
863 decode_hash_table_weakness (weakness));
866 DEFUN ("copy-hash-table", Fcopy_hash_table, 1, 1, 0, /*
867 Return a new hash table containing the same keys and values as HASH-TABLE.
868 The keys and values will not themselves be copied.
872 CONST Lisp_Hash_Table *ht_old = xhash_table (hash_table);
873 Lisp_Hash_Table *ht = alloc_lcrecord_type (Lisp_Hash_Table, &lrecord_hash_table);
875 copy_lcrecord (ht, ht_old);
877 ht->hentries = xnew_array (hentry, ht_old->size + 1);
878 memcpy (ht->hentries, ht_old->hentries, (ht_old->size + 1) * sizeof (hentry));
880 XSETHASH_TABLE (hash_table, ht);
882 if (! EQ (ht->next_weak, Qunbound))
884 ht->next_weak = Vall_weak_hash_tables;
885 Vall_weak_hash_tables = hash_table;
892 resize_hash_table (Lisp_Hash_Table *ht, size_t new_size)
894 hentry *old_entries, *new_entries, *old_sentinel, *new_sentinel, *e;
900 old_entries = ht->hentries;
902 ht->hentries = xnew_array (hentry, new_size + 1);
903 new_entries = ht->hentries;
905 old_sentinel = old_entries + old_size;
906 new_sentinel = new_entries + new_size;
908 for (e = new_entries; e <= new_sentinel; e++)
911 compute_hash_table_derived_values (ht);
913 for (e = old_entries; e < old_sentinel; e++)
914 if (!HENTRY_CLEAR_P (e))
916 hentry *probe = new_entries + HASH_CODE (e->key, ht);
917 LINEAR_PROBING_LOOP (probe, new_entries, new_size)
922 if (!DUMPEDP (old_entries))
927 reorganize_hash_table (Lisp_Hash_Table *ht)
929 resize_hash_table (ht, ht->size);
933 enlarge_hash_table (Lisp_Hash_Table *ht)
936 hash_table_size ((size_t) ((double) ht->size * ht->rehash_size));
937 resize_hash_table (ht, new_size);
941 find_hentry (Lisp_Object key, CONST Lisp_Hash_Table *ht)
943 hash_table_test_function_t test_function = ht->test_function;
944 hentry *entries = ht->hentries;
945 hentry *probe = entries + HASH_CODE (key, ht);
947 LINEAR_PROBING_LOOP (probe, entries, ht->size)
948 if (KEYS_EQUAL_P (probe->key, key, test_function))
954 DEFUN ("gethash", Fgethash, 2, 3, 0, /*
955 Find hash value for KEY in HASH-TABLE.
956 If there is no corresponding value, return DEFAULT (which defaults to nil).
958 (key, hash_table, default_))
960 CONST Lisp_Hash_Table *ht = xhash_table (hash_table);
961 hentry *e = find_hentry (key, ht);
963 return HENTRY_CLEAR_P (e) ? default_ : e->value;
966 DEFUN ("puthash", Fputhash, 3, 3, 0, /*
967 Hash KEY to VALUE in HASH-TABLE.
969 (key, value, hash_table))
971 Lisp_Hash_Table *ht = xhash_table (hash_table);
972 hentry *e = find_hentry (key, ht);
974 if (!HENTRY_CLEAR_P (e))
975 return e->value = value;
980 if (++ht->count >= ht->rehash_count)
981 enlarge_hash_table (ht);
986 /* Remove hentry pointed at by PROBE.
987 Subsequent entries are removed and reinserted.
988 We don't use tombstones - too wasteful. */
990 remhash_1 (Lisp_Hash_Table *ht, hentry *entries, hentry *probe)
992 size_t size = ht->size;
993 CLEAR_HENTRY (probe);
997 LINEAR_PROBING_LOOP (probe, entries, size)
999 Lisp_Object key = probe->key;
1000 hentry *probe2 = entries + HASH_CODE (key, ht);
1001 LINEAR_PROBING_LOOP (probe2, entries, size)
1002 if (EQ (probe2->key, key))
1003 /* hentry at probe doesn't need to move. */
1004 goto continue_outer_loop;
1005 /* Move hentry from probe to new home at probe2. */
1007 CLEAR_HENTRY (probe);
1008 continue_outer_loop: continue;
1012 DEFUN ("remhash", Fremhash, 2, 2, 0, /*
1013 Remove the entry for KEY from HASH-TABLE.
1014 Do nothing if there is no entry for KEY in HASH-TABLE.
1018 Lisp_Hash_Table *ht = xhash_table (hash_table);
1019 hentry *e = find_hentry (key, ht);
1021 if (HENTRY_CLEAR_P (e))
1024 remhash_1 (ht, ht->hentries, e);
1028 DEFUN ("clrhash", Fclrhash, 1, 1, 0, /*
1029 Remove all entries from HASH-TABLE, leaving it empty.
1033 Lisp_Hash_Table *ht = xhash_table (hash_table);
1034 hentry *e, *sentinel;
1036 for (e = ht->hentries, sentinel = e + ht->size; e < sentinel; e++)
1043 /************************************************************************/
1044 /* Accessor Functions */
1045 /************************************************************************/
1047 DEFUN ("hash-table-count", Fhash_table_count, 1, 1, 0, /*
1048 Return the number of entries in HASH-TABLE.
1052 return make_int (xhash_table (hash_table)->count);
1055 DEFUN ("hash-table-test", Fhash_table_test, 1, 1, 0, /*
1056 Return the test function of HASH-TABLE.
1057 This can be one of `eq', `eql' or `equal'.
1061 hash_table_test_function_t fun = xhash_table (hash_table)->test_function;
1063 return (fun == lisp_object_eql_equal ? Qeql :
1064 fun == lisp_object_equal_equal ? Qequal :
1068 DEFUN ("hash-table-size", Fhash_table_size, 1, 1, 0, /*
1069 Return the size of HASH-TABLE.
1070 This is the current number of slots in HASH-TABLE, whether occupied or not.
1074 return make_int (xhash_table (hash_table)->size);
1077 DEFUN ("hash-table-rehash-size", Fhash_table_rehash_size, 1, 1, 0, /*
1078 Return the current rehash size of HASH-TABLE.
1079 This is a float greater than 1.0; the factor by which HASH-TABLE
1080 is enlarged when the rehash threshold is exceeded.
1084 return make_float (xhash_table (hash_table)->rehash_size);
1087 DEFUN ("hash-table-rehash-threshold", Fhash_table_rehash_threshold, 1, 1, 0, /*
1088 Return the current rehash threshold of HASH-TABLE.
1089 This is a float between 0.0 and 1.0; the maximum `load factor' of HASH-TABLE,
1090 beyond which the HASH-TABLE is enlarged by rehashing.
1094 return make_float (hash_table_rehash_threshold (xhash_table (hash_table)));
1097 DEFUN ("hash-table-weakness", Fhash_table_weakness, 1, 1, 0, /*
1098 Return the weakness of HASH-TABLE.
1099 This can be one of `nil', `t', `key' or `value'.
1103 switch (xhash_table (hash_table)->weakness)
1105 case HASH_TABLE_WEAK: return Qt;
1106 case HASH_TABLE_KEY_WEAK: return Qkey;
1107 case HASH_TABLE_VALUE_WEAK: return Qvalue;
1108 default: return Qnil;
1112 /* obsolete as of 19990901 in xemacs-21.2 */
1113 DEFUN ("hash-table-type", Fhash_table_type, 1, 1, 0, /*
1114 Return the type of HASH-TABLE.
1115 This can be one of `non-weak', `weak', `key-weak' or `value-weak'.
1119 switch (xhash_table (hash_table)->weakness)
1121 case HASH_TABLE_WEAK: return Qweak;
1122 case HASH_TABLE_KEY_WEAK: return Qkey_weak;
1123 case HASH_TABLE_VALUE_WEAK: return Qvalue_weak;
1124 default: return Qnon_weak;
1128 /************************************************************************/
1129 /* Mapping Functions */
1130 /************************************************************************/
1131 DEFUN ("maphash", Fmaphash, 2, 2, 0, /*
1132 Map FUNCTION over entries in HASH-TABLE, calling it with two args,
1133 each key and value in HASH-TABLE.
1135 FUNCTION may not modify HASH-TABLE, with the one exception that FUNCTION
1136 may remhash or puthash the entry currently being processed by FUNCTION.
1138 (function, hash_table))
1140 CONST Lisp_Hash_Table *ht = xhash_table (hash_table);
1141 CONST hentry *e, *sentinel;
1143 for (e = ht->hentries, sentinel = e + ht->size; e < sentinel; e++)
1144 if (!HENTRY_CLEAR_P (e))
1146 Lisp_Object args[3], key;
1152 Ffuncall (countof (args), args);
1153 /* Has FUNCTION done a remhash? */
1154 if (!EQ (key, e->key) && !HENTRY_CLEAR_P (e))
1161 /* Map *C* function FUNCTION over the elements of a lisp hash table. */
1163 elisp_maphash (maphash_function_t function,
1164 Lisp_Object hash_table, void *extra_arg)
1166 CONST Lisp_Hash_Table *ht = XHASH_TABLE (hash_table);
1167 CONST hentry *e, *sentinel;
1169 for (e = ht->hentries, sentinel = e + ht->size; e < sentinel; e++)
1170 if (!HENTRY_CLEAR_P (e))
1175 if (function (key, e->value, extra_arg))
1177 /* Has FUNCTION done a remhash? */
1178 if (!EQ (key, e->key) && !HENTRY_CLEAR_P (e))
1183 /* Remove all elements of a lisp hash table satisfying *C* predicate PREDICATE. */
1185 elisp_map_remhash (maphash_function_t predicate,
1186 Lisp_Object hash_table, void *extra_arg)
1188 Lisp_Hash_Table *ht = XHASH_TABLE (hash_table);
1189 hentry *e, *entries, *sentinel;
1191 for (e = entries = ht->hentries, sentinel = e + ht->size; e < sentinel; e++)
1192 if (!HENTRY_CLEAR_P (e))
1195 if (predicate (e->key, e->value, extra_arg))
1197 remhash_1 (ht, entries, e);
1198 if (!HENTRY_CLEAR_P (e))
1205 /************************************************************************/
1206 /* garbage collecting weak hash tables */
1207 /************************************************************************/
1209 /* Complete the marking for semi-weak hash tables. */
1211 finish_marking_weak_hash_tables (void)
1213 Lisp_Object hash_table;
1216 for (hash_table = Vall_weak_hash_tables;
1218 hash_table = XHASH_TABLE (hash_table)->next_weak)
1220 CONST Lisp_Hash_Table *ht = XHASH_TABLE (hash_table);
1221 CONST hentry *e = ht->hentries;
1222 CONST hentry *sentinel = e + ht->size;
1224 if (! marked_p (hash_table))
1225 /* The hash table is probably garbage. Ignore it. */
1228 /* Now, scan over all the pairs. For all pairs that are
1229 half-marked, we may need to mark the other half if we're
1230 keeping this pair. */
1231 #define MARK_OBJ(obj) \
1232 do { if (!marked_p (obj)) mark_object (obj), did_mark = 1; } while (0)
1234 switch (ht->weakness)
1236 case HASH_TABLE_KEY_WEAK:
1237 for (; e < sentinel; e++)
1238 if (!HENTRY_CLEAR_P (e))
1239 if (marked_p (e->key))
1240 MARK_OBJ (e->value);
1243 case HASH_TABLE_VALUE_WEAK:
1244 for (; e < sentinel; e++)
1245 if (!HENTRY_CLEAR_P (e))
1246 if (marked_p (e->value))
1250 case HASH_TABLE_KEY_CAR_WEAK:
1251 for (; e < sentinel; e++)
1252 if (!HENTRY_CLEAR_P (e))
1253 if (!CONSP (e->key) || marked_p (XCAR (e->key)))
1256 MARK_OBJ (e->value);
1260 case HASH_TABLE_VALUE_CAR_WEAK:
1261 for (; e < sentinel; e++)
1262 if (!HENTRY_CLEAR_P (e))
1263 if (!CONSP (e->value) || marked_p (XCAR (e->value)))
1266 MARK_OBJ (e->value);
1279 prune_weak_hash_tables (void)
1281 Lisp_Object hash_table, prev = Qnil;
1282 for (hash_table = Vall_weak_hash_tables;
1284 hash_table = XHASH_TABLE (hash_table)->next_weak)
1286 if (! marked_p (hash_table))
1288 /* This hash table itself is garbage. Remove it from the list. */
1290 Vall_weak_hash_tables = XHASH_TABLE (hash_table)->next_weak;
1292 XHASH_TABLE (prev)->next_weak = XHASH_TABLE (hash_table)->next_weak;
1296 /* Now, scan over all the pairs. Remove all of the pairs
1297 in which the key or value, or both, is unmarked
1298 (depending on the weakness of the hash table). */
1299 Lisp_Hash_Table *ht = XHASH_TABLE (hash_table);
1300 hentry *entries = ht->hentries;
1301 hentry *sentinel = entries + ht->size;
1304 for (e = entries; e < sentinel; e++)
1305 if (!HENTRY_CLEAR_P (e))
1308 if (!marked_p (e->key) || !marked_p (e->value))
1310 remhash_1 (ht, entries, e);
1311 if (!HENTRY_CLEAR_P (e))
1321 /* Return a hash value for an array of Lisp_Objects of size SIZE. */
1324 internal_array_hash (Lisp_Object *arr, int size, int depth)
1327 unsigned long hash = 0;
1331 for (i = 0; i < size; i++)
1332 hash = HASH2 (hash, internal_hash (arr[i], depth + 1));
1336 /* just pick five elements scattered throughout the array.
1337 A slightly better approach would be to offset by some
1338 noise factor from the points chosen below. */
1339 for (i = 0; i < 5; i++)
1340 hash = HASH2 (hash, internal_hash (arr[i*size/5], depth + 1));
1345 /* Return a hash value for a Lisp_Object. This is for use when hashing
1346 objects with the comparison being `equal' (for `eq', you can just
1347 use the Lisp_Object itself as the hash value). You need to make a
1348 tradeoff between the speed of the hash function and how good the
1349 hashing is. In particular, the hash function needs to be FAST,
1350 so you can't just traipse down the whole tree hashing everything
1351 together. Most of the time, objects will differ in the first
1352 few elements you hash. Thus, we only go to a short depth (5)
1353 and only hash at most 5 elements out of a vector. Theoretically
1354 we could still take 5^5 time (a big big number) to compute a
1355 hash, but practically this won't ever happen. */
1358 internal_hash (Lisp_Object obj, int depth)
1364 /* no point in worrying about tail recursion, since we're not
1366 return HASH2 (internal_hash (XCAR (obj), depth + 1),
1367 internal_hash (XCDR (obj), depth + 1));
1371 return hash_string (XSTRING_DATA (obj), XSTRING_LENGTH (obj));
1375 return HASH2 (XVECTOR_LENGTH (obj),
1376 internal_array_hash (XVECTOR_DATA (obj),
1377 XVECTOR_LENGTH (obj),
1382 CONST struct lrecord_implementation
1383 *imp = XRECORD_LHEADER_IMPLEMENTATION (obj);
1385 return imp->hash (obj, depth);
1388 return LISP_HASH (obj);
1391 DEFUN ("sxhash", Fsxhash, 1, 1, 0, /*
1392 Return a hash value for OBJECT.
1393 (equal obj1 obj2) implies (= (sxhash obj1) (sxhash obj2)).
1397 return make_int (internal_hash (object, 0));
1401 xxDEFUN ("internal-hash-value", Finternal_hash_value, 1, 1, 0, /*
1402 Hash value of OBJECT. For debugging.
1403 The value is returned as (HIGH . LOW).
1407 /* This function is pretty 32bit-centric. */
1408 unsigned long hash = internal_hash (object, 0);
1409 return Fcons (hash >> 16, hash & 0xffff);
1414 /************************************************************************/
1415 /* initialization */
1416 /************************************************************************/
1419 syms_of_elhash (void)
1421 DEFSUBR (Fhash_table_p);
1422 DEFSUBR (Fmake_hash_table);
1423 DEFSUBR (Fcopy_hash_table);
1429 DEFSUBR (Fhash_table_count);
1430 DEFSUBR (Fhash_table_test);
1431 DEFSUBR (Fhash_table_size);
1432 DEFSUBR (Fhash_table_rehash_size);
1433 DEFSUBR (Fhash_table_rehash_threshold);
1434 DEFSUBR (Fhash_table_weakness);
1435 DEFSUBR (Fhash_table_type); /* obsolete */
1438 DEFSUBR (Finternal_hash_value);
1441 defsymbol (&Qhash_tablep, "hash-table-p");
1442 defsymbol (&Qhash_table, "hash-table");
1443 defsymbol (&Qhashtable, "hashtable");
1444 defsymbol (&Qweakness, "weakness");
1445 defsymbol (&Qvalue, "value");
1446 defsymbol (&Qrehash_size, "rehash-size");
1447 defsymbol (&Qrehash_threshold, "rehash-threshold");
1449 defsymbol (&Qweak, "weak"); /* obsolete */
1450 defsymbol (&Qkey_weak, "key-weak"); /* obsolete */
1451 defsymbol (&Qvalue_weak, "value-weak"); /* obsolete */
1452 defsymbol (&Qnon_weak, "non-weak"); /* obsolete */
1454 defkeyword (&Q_test, ":test");
1455 defkeyword (&Q_size, ":size");
1456 defkeyword (&Q_rehash_size, ":rehash-size");
1457 defkeyword (&Q_rehash_threshold, ":rehash-threshold");
1458 defkeyword (&Q_weakness, ":weakness");
1459 defkeyword (&Q_type, ":type"); /* obsolete */
1463 vars_of_elhash (void)
1465 /* This must NOT be staticpro'd */
1466 Vall_weak_hash_tables = Qnil;
1467 pdump_wire_list (&Vall_weak_hash_tables);