PostgreSQL Source Code: src/backend/nodes/bitmapset.c Source File

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bitmapset.c
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1/*-------------------------------------------------------------------------
2 *
3 * bitmapset.c
4 * PostgreSQL generic bitmap set package
5 *
6 * A bitmap set can represent any set of nonnegative integers, although
7 * it is mainly intended for sets where the maximum value is not large,
8 * say at most a few hundred. By convention, we always represent a set with
9 * the minimum possible number of words, i.e, there are never any trailing
10 * zero words. Enforcing this requires that an empty set is represented as
11 * NULL. Because an empty Bitmapset is represented as NULL, a non-NULL
12 * Bitmapset always has at least 1 Bitmapword. We can exploit this fact to
13 * speed up various loops over the Bitmapset's words array by using "do while"
14 * loops instead of "for" loops. This means the code does not waste time
15 * checking the loop condition before the first iteration. For Bitmapsets
16 * containing only a single word (likely the majority of them) this halves the
17 * number of loop condition checks.
18 *
19 * Callers must ensure that the set returned by functions in this file which
20 * adjust the members of an existing set is assigned to all pointers pointing
21 * to that existing set. No guarantees are made that we'll ever modify the
22 * existing set in-place and return it.
23 *
24 * To help find bugs caused by callers failing to record the return value of
25 * the function which manipulates an existing set, we support building with
26 * REALLOCATE_BITMAPSETS. This results in the set being reallocated each time
27 * the set is altered and the existing being pfreed. This is useful as if any
28 * references still exist to the old set, we're more likely to notice as
29 * any users of the old set will be accessing pfree'd memory. This option is
30 * only intended to be used for debugging.
31 *
32 * Copyright (c) 2003-2025, PostgreSQL Global Development Group
33 *
34 * IDENTIFICATION
35 * src/backend/nodes/bitmapset.c
36 *
37 *-------------------------------------------------------------------------
38 */
39#include "postgres.h"
40
41#include "common/hashfn.h"
42#include "nodes/bitmapset.h"
43#include "nodes/pg_list.h"
44#include "port/pg_bitutils.h"
45
46
47 #define WORDNUM(x) ((x) / BITS_PER_BITMAPWORD)
48 #define BITNUM(x) ((x) % BITS_PER_BITMAPWORD)
49
50 #define BITMAPSET_SIZE(nwords) \
51 (offsetof(Bitmapset, words) + (nwords) * sizeof(bitmapword))
52
53/*----------
54 * This is a well-known cute trick for isolating the rightmost one-bit
55 * in a word. It assumes two's complement arithmetic. Consider any
56 * nonzero value, and focus attention on the rightmost one. The value is
57 * then something like
58 * xxxxxx10000
59 * where x's are unspecified bits. The two's complement negative is formed
60 * by inverting all the bits and adding one. Inversion gives
61 * yyyyyy01111
62 * where each y is the inverse of the corresponding x. Incrementing gives
63 * yyyyyy10000
64 * and then ANDing with the original value gives
65 * 00000010000
66 * This works for all cases except original value = zero, where of course
67 * we get zero.
68 *----------
69 */
70 #define RIGHTMOST_ONE(x) ((signedbitmapword) (x) & -((signedbitmapword) (x)))
71
72 #define HAS_MULTIPLE_ONES(x) ((bitmapword) RIGHTMOST_ONE(x) != (x))
73
74#ifdef USE_ASSERT_CHECKING
75/*
76 * bms_is_valid_set - for cassert builds to check for valid sets
77 */
78static bool
79bms_is_valid_set(const Bitmapset *a)
80{
81 /* NULL is the correct representation of an empty set */
82 if (a == NULL)
83 return true;
84
85 /* check the node tag is set correctly. pfree'd pointer, maybe? */
86 if (!IsA(a, Bitmapset))
87 return false;
88
89 /* trailing zero words are not allowed */
90 if (a->words[a->nwords - 1] == 0)
91 return false;
92
93 return true;
94}
95#endif
96
97#ifdef REALLOCATE_BITMAPSETS
98/*
99 * bms_copy_and_free
100 * Only required in REALLOCATE_BITMAPSETS builds. Provide a simple way
101 * to return a freshly allocated set and pfree the original.
102 *
103 * Note: callers which accept multiple sets must be careful when calling this
104 * function to clone one parameter as other parameters may point to the same
105 * set. A good option is to call this just before returning the resulting
106 * set.
107 */
108static Bitmapset *
109bms_copy_and_free(Bitmapset *a)
110{
111 Bitmapset *c = bms_copy(a);
112
113 bms_free(a);
114 return c;
115}
116#endif
117
118/*
119 * bms_copy - make a palloc'd copy of a bitmapset
120 */
121Bitmapset *
122 bms_copy(const Bitmapset *a)
123{
124 Bitmapset *result;
125 size_t size;
126
127 Assert(bms_is_valid_set(a));
128
129 if (a == NULL)
130 return NULL;
131
132 size = BITMAPSET_SIZE(a->nwords);
133 result = (Bitmapset *) palloc(size);
134 memcpy(result, a, size);
135 return result;
136}
137
138/*
139 * bms_equal - are two bitmapsets equal? or both NULL?
140 */
141bool
142 bms_equal(const Bitmapset *a, const Bitmapset *b)
143{
144 int i;
145
146 Assert(bms_is_valid_set(a));
147 Assert(bms_is_valid_set(b));
148
149 /* Handle cases where either input is NULL */
150 if (a == NULL)
151 {
152 if (b == NULL)
153 return true;
154 return false;
155 }
156 else if (b == NULL)
157 return false;
158
159 /* can't be equal if the word counts don't match */
160 if (a->nwords != b->nwords)
161 return false;
162
163 /* check each word matches */
164 i = 0;
165 do
166 {
167 if (a->words[i] != b->words[i])
168 return false;
169 } while (++i < a->nwords);
170
171 return true;
172}
173
174/*
175 * bms_compare - qsort-style comparator for bitmapsets
176 *
177 * This guarantees to report values as equal iff bms_equal would say they are
178 * equal. Otherwise, the highest-numbered bit that is set in one value but
179 * not the other determines the result. (This rule means that, for example,
180 * {6} is greater than {5}, which seems plausible.)
181 */
182int
183 bms_compare(const Bitmapset *a, const Bitmapset *b)
184{
185 int i;
186
187 Assert(bms_is_valid_set(a));
188 Assert(bms_is_valid_set(b));
189
190 /* Handle cases where either input is NULL */
191 if (a == NULL)
192 return (b == NULL) ? 0 : -1;
193 else if (b == NULL)
194 return +1;
195
196 /* the set with the most words must be greater */
197 if (a->nwords != b->nwords)
198 return (a->nwords > b->nwords) ? +1 : -1;
199
200 i = a->nwords - 1;
201 do
202 {
203 bitmapword aw = a->words[i];
204 bitmapword bw = b->words[i];
205
206 if (aw != bw)
207 return (aw > bw) ? +1 : -1;
208 } while (--i >= 0);
209 return 0;
210}
211
212/*
213 * bms_make_singleton - build a bitmapset containing a single member
214 */
215Bitmapset *
216 bms_make_singleton(int x)
217{
218 Bitmapset *result;
219 int wordnum,
220 bitnum;
221
222 if (x < 0)
223 elog(ERROR, "negative bitmapset member not allowed");
224 wordnum = WORDNUM(x);
225 bitnum = BITNUM(x);
226 result = (Bitmapset *) palloc0(BITMAPSET_SIZE(wordnum + 1));
227 result->type = T_Bitmapset;
228 result->nwords = wordnum + 1;
229 result->words[wordnum] = ((bitmapword) 1 << bitnum);
230 return result;
231}
232
233/*
234 * bms_free - free a bitmapset
235 *
236 * Same as pfree except for allowing NULL input
237 */
238void
239 bms_free(Bitmapset *a)
240{
241 if (a)
242 pfree(a);
243}
244
245
246/*
247 * bms_union - create and return a new set containing all members from both
248 * input sets. Both inputs are left unmodified.
249 */
250Bitmapset *
251 bms_union(const Bitmapset *a, const Bitmapset *b)
252{
253 Bitmapset *result;
254 const Bitmapset *other;
255 int otherlen;
256 int i;
257
258 Assert(bms_is_valid_set(a));
259 Assert(bms_is_valid_set(b));
260
261 /* Handle cases where either input is NULL */
262 if (a == NULL)
263 return bms_copy(b);
264 if (b == NULL)
265 return bms_copy(a);
266 /* Identify shorter and longer input; copy the longer one */
267 if (a->nwords <= b->nwords)
268 {
269 result = bms_copy(b);
270 other = a;
271 }
272 else
273 {
274 result = bms_copy(a);
275 other = b;
276 }
277 /* And union the shorter input into the result */
278 otherlen = other->nwords;
279 i = 0;
280 do
281 {
282 result->words[i] |= other->words[i];
283 } while (++i < otherlen);
284 return result;
285}
286
287/*
288 * bms_intersect - create and return a new set containing members which both
289 * input sets have in common. Both inputs are left unmodified.
290 */
291Bitmapset *
292 bms_intersect(const Bitmapset *a, const Bitmapset *b)
293{
294 Bitmapset *result;
295 const Bitmapset *other;
296 int lastnonzero;
297 int resultlen;
298 int i;
299
300 Assert(bms_is_valid_set(a));
301 Assert(bms_is_valid_set(b));
302
303 /* Handle cases where either input is NULL */
304 if (a == NULL || b == NULL)
305 return NULL;
306
307 /* Identify shorter and longer input; copy the shorter one */
308 if (a->nwords <= b->nwords)
309 {
310 result = bms_copy(a);
311 other = b;
312 }
313 else
314 {
315 result = bms_copy(b);
316 other = a;
317 }
318 /* And intersect the longer input with the result */
319 resultlen = result->nwords;
320 lastnonzero = -1;
321 i = 0;
322 do
323 {
324 result->words[i] &= other->words[i];
325
326 if (result->words[i] != 0)
327 lastnonzero = i;
328 } while (++i < resultlen);
329 /* If we computed an empty result, we must return NULL */
330 if (lastnonzero == -1)
331 {
332 pfree(result);
333 return NULL;
334 }
335
336 /* get rid of trailing zero words */
337 result->nwords = lastnonzero + 1;
338 return result;
339}
340
341/*
342 * bms_difference - create and return a new set containing all the members of
343 * 'a' without the members of 'b'.
344 */
345Bitmapset *
346 bms_difference(const Bitmapset *a, const Bitmapset *b)
347{
348 Bitmapset *result;
349 int i;
350
351 Assert(bms_is_valid_set(a));
352 Assert(bms_is_valid_set(b));
353
354 /* Handle cases where either input is NULL */
355 if (a == NULL)
356 return NULL;
357 if (b == NULL)
358 return bms_copy(a);
359
360 /*
361 * In Postgres' usage, an empty result is a very common case, so it's
362 * worth optimizing for that by testing bms_nonempty_difference(). This
363 * saves us a palloc/pfree cycle compared to checking after-the-fact.
364 */
365 if (!bms_nonempty_difference(a, b))
366 return NULL;
367
368 /* Copy the left input */
369 result = bms_copy(a);
370
371 /* And remove b's bits from result */
372 if (result->nwords > b->nwords)
373 {
374 /*
375 * We'll never need to remove trailing zero words when 'a' has more
376 * words than 'b' as the additional words must be non-zero.
377 */
378 i = 0;
379 do
380 {
381 result->words[i] &= ~b->words[i];
382 } while (++i < b->nwords);
383 }
384 else
385 {
386 int lastnonzero = -1;
387
388 /* we may need to remove trailing zero words from the result. */
389 i = 0;
390 do
391 {
392 result->words[i] &= ~b->words[i];
393
394 /* remember the last non-zero word */
395 if (result->words[i] != 0)
396 lastnonzero = i;
397 } while (++i < result->nwords);
398
399 /* trim off trailing zero words */
400 result->nwords = lastnonzero + 1;
401 }
402 Assert(result->nwords != 0);
403
404 /* Need not check for empty result, since we handled that case above */
405 return result;
406}
407
408/*
409 * bms_is_subset - is A a subset of B?
410 */
411bool
412 bms_is_subset(const Bitmapset *a, const Bitmapset *b)
413{
414 int i;
415
416 Assert(bms_is_valid_set(a));
417 Assert(bms_is_valid_set(b));
418
419 /* Handle cases where either input is NULL */
420 if (a == NULL)
421 return true; /* empty set is a subset of anything */
422 if (b == NULL)
423 return false;
424
425 /* 'a' can't be a subset of 'b' if it contains more words */
426 if (a->nwords > b->nwords)
427 return false;
428
429 /* Check all 'a' members are set in 'b' */
430 i = 0;
431 do
432 {
433 if ((a->words[i] & ~b->words[i]) != 0)
434 return false;
435 } while (++i < a->nwords);
436 return true;
437}
438
439/*
440 * bms_subset_compare - compare A and B for equality/subset relationships
441 *
442 * This is more efficient than testing bms_is_subset in both directions.
443 */
444BMS_Comparison
445 bms_subset_compare(const Bitmapset *a, const Bitmapset *b)
446{
447 BMS_Comparison result;
448 int shortlen;
449 int i;
450
451 Assert(bms_is_valid_set(a));
452 Assert(bms_is_valid_set(b));
453
454 /* Handle cases where either input is NULL */
455 if (a == NULL)
456 {
457 if (b == NULL)
458 return BMS_EQUAL;
459 return BMS_SUBSET1;
460 }
461 if (b == NULL)
462 return BMS_SUBSET2;
463
464 /* Check common words */
465 result = BMS_EQUAL; /* status so far */
466 shortlen = Min(a->nwords, b->nwords);
467 i = 0;
468 do
469 {
470 bitmapword aword = a->words[i];
471 bitmapword bword = b->words[i];
472
473 if ((aword & ~bword) != 0)
474 {
475 /* a is not a subset of b */
476 if (result == BMS_SUBSET1)
477 return BMS_DIFFERENT;
478 result = BMS_SUBSET2;
479 }
480 if ((bword & ~aword) != 0)
481 {
482 /* b is not a subset of a */
483 if (result == BMS_SUBSET2)
484 return BMS_DIFFERENT;
485 result = BMS_SUBSET1;
486 }
487 } while (++i < shortlen);
488 /* Check extra words */
489 if (a->nwords > b->nwords)
490 {
491 /* if a has more words then a is not a subset of b */
492 if (result == BMS_SUBSET1)
493 return BMS_DIFFERENT;
494 return BMS_SUBSET2;
495 }
496 else if (a->nwords < b->nwords)
497 {
498 /* if b has more words then b is not a subset of a */
499 if (result == BMS_SUBSET2)
500 return BMS_DIFFERENT;
501 return BMS_SUBSET1;
502 }
503 return result;
504}
505
506/*
507 * bms_is_member - is X a member of A?
508 */
509bool
510 bms_is_member(int x, const Bitmapset *a)
511{
512 int wordnum,
513 bitnum;
514
515 Assert(bms_is_valid_set(a));
516
517 /* XXX better to just return false for x<0 ? */
518 if (x < 0)
519 elog(ERROR, "negative bitmapset member not allowed");
520 if (a == NULL)
521 return false;
522
523 wordnum = WORDNUM(x);
524 bitnum = BITNUM(x);
525 if (wordnum >= a->nwords)
526 return false;
527 if ((a->words[wordnum] & ((bitmapword) 1 << bitnum)) != 0)
528 return true;
529 return false;
530}
531
532/*
533 * bms_member_index
534 * determine 0-based index of member x in the bitmap
535 *
536 * Returns (-1) when x is not a member.
537 */
538int
539 bms_member_index(Bitmapset *a, int x)
540{
541 int i;
542 int bitnum;
543 int wordnum;
544 int result = 0;
545 bitmapword mask;
546
547 Assert(bms_is_valid_set(a));
548
549 /* return -1 if not a member of the bitmap */
550 if (!bms_is_member(x, a))
551 return -1;
552
553 wordnum = WORDNUM(x);
554 bitnum = BITNUM(x);
555
556 /* count bits in preceding words */
557 for (i = 0; i < wordnum; i++)
558 {
559 bitmapword w = a->words[i];
560
561 /* No need to count the bits in a zero word */
562 if (w != 0)
563 result += bmw_popcount(w);
564 }
565
566 /*
567 * Now add bits of the last word, but only those before the item. We can
568 * do that by applying a mask and then using popcount again. To get
569 * 0-based index, we want to count only preceding bits, not the item
570 * itself, so we subtract 1.
571 */
572 mask = ((bitmapword) 1 << bitnum) - 1;
573 result += bmw_popcount(a->words[wordnum] & mask);
574
575 return result;
576}
577
578/*
579 * bms_overlap - do sets overlap (ie, have a nonempty intersection)?
580 */
581bool
582 bms_overlap(const Bitmapset *a, const Bitmapset *b)
583{
584 int shortlen;
585 int i;
586
587 Assert(bms_is_valid_set(a));
588 Assert(bms_is_valid_set(b));
589
590 /* Handle cases where either input is NULL */
591 if (a == NULL || b == NULL)
592 return false;
593 /* Check words in common */
594 shortlen = Min(a->nwords, b->nwords);
595 i = 0;
596 do
597 {
598 if ((a->words[i] & b->words[i]) != 0)
599 return true;
600 } while (++i < shortlen);
601 return false;
602}
603
604/*
605 * bms_overlap_list - does a set overlap an integer list?
606 */
607bool
608 bms_overlap_list(const Bitmapset *a, const List *b)
609{
610 ListCell *lc;
611 int wordnum,
612 bitnum;
613
614 Assert(bms_is_valid_set(a));
615
616 if (a == NULL || b == NIL)
617 return false;
618
619 foreach(lc, b)
620 {
621 int x = lfirst_int(lc);
622
623 if (x < 0)
624 elog(ERROR, "negative bitmapset member not allowed");
625 wordnum = WORDNUM(x);
626 bitnum = BITNUM(x);
627 if (wordnum < a->nwords)
628 if ((a->words[wordnum] & ((bitmapword) 1 << bitnum)) != 0)
629 return true;
630 }
631
632 return false;
633}
634
635/*
636 * bms_nonempty_difference - do sets have a nonempty difference?
637 *
638 * i.e., are any members set in 'a' that are not also set in 'b'.
639 */
640bool
641 bms_nonempty_difference(const Bitmapset *a, const Bitmapset *b)
642{
643 int i;
644
645 Assert(bms_is_valid_set(a));
646 Assert(bms_is_valid_set(b));
647
648 /* Handle cases where either input is NULL */
649 if (a == NULL)
650 return false;
651 if (b == NULL)
652 return true;
653 /* if 'a' has more words then it must contain additional members */
654 if (a->nwords > b->nwords)
655 return true;
656 /* Check all 'a' members are set in 'b' */
657 i = 0;
658 do
659 {
660 if ((a->words[i] & ~b->words[i]) != 0)
661 return true;
662 } while (++i < a->nwords);
663 return false;
664}
665
666/*
667 * bms_singleton_member - return the sole integer member of set
668 *
669 * Raises error if |a| is not 1.
670 */
671int
672 bms_singleton_member(const Bitmapset *a)
673{
674 int result = -1;
675 int nwords;
676 int wordnum;
677
678 Assert(bms_is_valid_set(a));
679
680 if (a == NULL)
681 elog(ERROR, "bitmapset is empty");
682
683 nwords = a->nwords;
684 wordnum = 0;
685 do
686 {
687 bitmapword w = a->words[wordnum];
688
689 if (w != 0)
690 {
691 if (result >= 0 || HAS_MULTIPLE_ONES(w))
692 elog(ERROR, "bitmapset has multiple members");
693 result = wordnum * BITS_PER_BITMAPWORD;
694 result += bmw_rightmost_one_pos(w);
695 }
696 } while (++wordnum < nwords);
697
698 /* we don't expect non-NULL sets to be empty */
699 Assert(result >= 0);
700 return result;
701}
702
703/*
704 * bms_get_singleton_member
705 *
706 * Test whether the given set is a singleton.
707 * If so, set *member to the value of its sole member, and return true.
708 * If not, return false, without changing *member.
709 *
710 * This is more convenient and faster than calling bms_membership() and then
711 * bms_singleton_member(), if we don't care about distinguishing empty sets
712 * from multiple-member sets.
713 */
714bool
715 bms_get_singleton_member(const Bitmapset *a, int *member)
716{
717 int result = -1;
718 int nwords;
719 int wordnum;
720
721 Assert(bms_is_valid_set(a));
722
723 if (a == NULL)
724 return false;
725
726 nwords = a->nwords;
727 wordnum = 0;
728 do
729 {
730 bitmapword w = a->words[wordnum];
731
732 if (w != 0)
733 {
734 if (result >= 0 || HAS_MULTIPLE_ONES(w))
735 return false;
736 result = wordnum * BITS_PER_BITMAPWORD;
737 result += bmw_rightmost_one_pos(w);
738 }
739 } while (++wordnum < nwords);
740
741 /* we don't expect non-NULL sets to be empty */
742 Assert(result >= 0);
743 *member = result;
744 return true;
745}
746
747/*
748 * bms_num_members - count members of set
749 */
750int
751 bms_num_members(const Bitmapset *a)
752{
753 int result = 0;
754 int nwords;
755 int wordnum;
756
757 Assert(bms_is_valid_set(a));
758
759 if (a == NULL)
760 return 0;
761
762 nwords = a->nwords;
763 wordnum = 0;
764 do
765 {
766 bitmapword w = a->words[wordnum];
767
768 /* No need to count the bits in a zero word */
769 if (w != 0)
770 result += bmw_popcount(w);
771 } while (++wordnum < nwords);
772 return result;
773}
774
775/*
776 * bms_membership - does a set have zero, one, or multiple members?
777 *
778 * This is faster than making an exact count with bms_num_members().
779 */
780BMS_Membership
781 bms_membership(const Bitmapset *a)
782{
783 BMS_Membership result = BMS_EMPTY_SET;
784 int nwords;
785 int wordnum;
786
787 Assert(bms_is_valid_set(a));
788
789 if (a == NULL)
790 return BMS_EMPTY_SET;
791
792 nwords = a->nwords;
793 wordnum = 0;
794 do
795 {
796 bitmapword w = a->words[wordnum];
797
798 if (w != 0)
799 {
800 if (result != BMS_EMPTY_SET || HAS_MULTIPLE_ONES(w))
801 return BMS_MULTIPLE;
802 result = BMS_SINGLETON;
803 }
804 } while (++wordnum < nwords);
805 return result;
806}
807
808
809/*
810 * bms_add_member - add a specified member to set
811 *
812 * 'a' is recycled when possible.
813 */
814Bitmapset *
815 bms_add_member(Bitmapset *a, int x)
816{
817 int wordnum,
818 bitnum;
819
820 Assert(bms_is_valid_set(a));
821
822 if (x < 0)
823 elog(ERROR, "negative bitmapset member not allowed");
824 if (a == NULL)
825 return bms_make_singleton(x);
826
827 wordnum = WORDNUM(x);
828 bitnum = BITNUM(x);
829
830 /* enlarge the set if necessary */
831 if (wordnum >= a->nwords)
832 {
833 int oldnwords = a->nwords;
834 int i;
835
836 a = (Bitmapset *) repalloc(a, BITMAPSET_SIZE(wordnum + 1));
837 a->nwords = wordnum + 1;
838 /* zero out the enlarged portion */
839 i = oldnwords;
840 do
841 {
842 a->words[i] = 0;
843 } while (++i < a->nwords);
844 }
845
846 a->words[wordnum] |= ((bitmapword) 1 << bitnum);
847
848#ifdef REALLOCATE_BITMAPSETS
849
850 /*
851 * There's no guarantee that the repalloc returned a new pointer, so copy
852 * and free unconditionally here.
853 */
854 a = bms_copy_and_free(a);
855#endif
856
857 return a;
858}
859
860/*
861 * bms_del_member - remove a specified member from set
862 *
863 * No error if x is not currently a member of set
864 *
865 * 'a' is recycled when possible.
866 */
867Bitmapset *
868 bms_del_member(Bitmapset *a, int x)
869{
870 int wordnum,
871 bitnum;
872
873 Assert(bms_is_valid_set(a));
874
875 if (x < 0)
876 elog(ERROR, "negative bitmapset member not allowed");
877 if (a == NULL)
878 return NULL;
879
880 wordnum = WORDNUM(x);
881 bitnum = BITNUM(x);
882
883#ifdef REALLOCATE_BITMAPSETS
884 a = bms_copy_and_free(a);
885#endif
886
887 /* member can't exist. Return 'a' unmodified */
888 if (unlikely(wordnum >= a->nwords))
889 return a;
890
891 a->words[wordnum] &= ~((bitmapword) 1 << bitnum);
892
893 /* when last word becomes empty, trim off all trailing empty words */
894 if (a->words[wordnum] == 0 && wordnum == a->nwords - 1)
895 {
896 /* find the last non-empty word and make that the new final word */
897 for (int i = wordnum - 1; i >= 0; i--)
898 {
899 if (a->words[i] != 0)
900 {
901 a->nwords = i + 1;
902 return a;
903 }
904 }
905
906 /* the set is now empty */
907 pfree(a);
908 return NULL;
909 }
910 return a;
911}
912
913/*
914 * bms_add_members - like bms_union, but left input is recycled when possible
915 */
916Bitmapset *
917 bms_add_members(Bitmapset *a, const Bitmapset *b)
918{
919 Bitmapset *result;
920 const Bitmapset *other;
921 int otherlen;
922 int i;
923
924 Assert(bms_is_valid_set(a));
925 Assert(bms_is_valid_set(b));
926
927 /* Handle cases where either input is NULL */
928 if (a == NULL)
929 return bms_copy(b);
930 if (b == NULL)
931 {
932#ifdef REALLOCATE_BITMAPSETS
933 a = bms_copy_and_free(a);
934#endif
935
936 return a;
937 }
938 /* Identify shorter and longer input; copy the longer one if needed */
939 if (a->nwords < b->nwords)
940 {
941 result = bms_copy(b);
942 other = a;
943 }
944 else
945 {
946 result = a;
947 other = b;
948 }
949 /* And union the shorter input into the result */
950 otherlen = other->nwords;
951 i = 0;
952 do
953 {
954 result->words[i] |= other->words[i];
955 } while (++i < otherlen);
956 if (result != a)
957 pfree(a);
958#ifdef REALLOCATE_BITMAPSETS
959 else
960 result = bms_copy_and_free(result);
961#endif
962
963 return result;
964}
965
966/*
967 * bms_replace_members
968 * Remove all existing members from 'a' and repopulate the set with members
969 * from 'b', recycling 'a', when possible.
970 */
971Bitmapset *
972 bms_replace_members(Bitmapset *a, const Bitmapset *b)
973{
974 int i;
975
976 Assert(bms_is_valid_set(a));
977 Assert(bms_is_valid_set(b));
978
979 if (a == NULL)
980 return bms_copy(b);
981 if (b == NULL)
982 {
983 pfree(a);
984 return NULL;
985 }
986
987 if (a->nwords < b->nwords)
988 a = (Bitmapset *) repalloc(a, BITMAPSET_SIZE(b->nwords));
989
990 i = 0;
991 do
992 {
993 a->words[i] = b->words[i];
994 } while (++i < b->nwords);
995
996 a->nwords = b->nwords;
997
998#ifdef REALLOCATE_BITMAPSETS
999
1000 /*
1001 * There's no guarantee that the repalloc returned a new pointer, so copy
1002 * and free unconditionally here.
1003 */
1004 a = bms_copy_and_free(a);
1005#endif
1006
1007 return a;
1008}
1009
1010/*
1011 * bms_add_range
1012 * Add members in the range of 'lower' to 'upper' to the set.
1013 *
1014 * Note this could also be done by calling bms_add_member in a loop, however,
1015 * using this function will be faster when the range is large as we work at
1016 * the bitmapword level rather than at bit level.
1017 */
1018Bitmapset *
1019 bms_add_range(Bitmapset *a, int lower, int upper)
1020{
1021 int lwordnum,
1022 lbitnum,
1023 uwordnum,
1024 ushiftbits,
1025 wordnum;
1026
1027 Assert(bms_is_valid_set(a));
1028
1029 /* do nothing if nothing is called for, without further checking */
1030 if (upper < lower)
1031 {
1032#ifdef REALLOCATE_BITMAPSETS
1033 a = bms_copy_and_free(a);
1034#endif
1035
1036 return a;
1037 }
1038
1039 if (lower < 0)
1040 elog(ERROR, "negative bitmapset member not allowed");
1041 uwordnum = WORDNUM(upper);
1042
1043 if (a == NULL)
1044 {
1045 a = (Bitmapset *) palloc0(BITMAPSET_SIZE(uwordnum + 1));
1046 a->type = T_Bitmapset;
1047 a->nwords = uwordnum + 1;
1048 }
1049 else if (uwordnum >= a->nwords)
1050 {
1051 int oldnwords = a->nwords;
1052 int i;
1053
1054 /* ensure we have enough words to store the upper bit */
1055 a = (Bitmapset *) repalloc(a, BITMAPSET_SIZE(uwordnum + 1));
1056 a->nwords = uwordnum + 1;
1057 /* zero out the enlarged portion */
1058 i = oldnwords;
1059 do
1060 {
1061 a->words[i] = 0;
1062 } while (++i < a->nwords);
1063 }
1064
1065 wordnum = lwordnum = WORDNUM(lower);
1066
1067 lbitnum = BITNUM(lower);
1068 ushiftbits = BITS_PER_BITMAPWORD - (BITNUM(upper) + 1);
1069
1070 /*
1071 * Special case when lwordnum is the same as uwordnum we must perform the
1072 * upper and lower masking on the word.
1073 */
1074 if (lwordnum == uwordnum)
1075 {
1076 a->words[lwordnum] |= ~(bitmapword) (((bitmapword) 1 << lbitnum) - 1)
1077 & (~(bitmapword) 0) >> ushiftbits;
1078 }
1079 else
1080 {
1081 /* turn on lbitnum and all bits left of it */
1082 a->words[wordnum++] |= ~(bitmapword) (((bitmapword) 1 << lbitnum) - 1);
1083
1084 /* turn on all bits for any intermediate words */
1085 while (wordnum < uwordnum)
1086 a->words[wordnum++] = ~(bitmapword) 0;
1087
1088 /* turn on upper's bit and all bits right of it. */
1089 a->words[uwordnum] |= (~(bitmapword) 0) >> ushiftbits;
1090 }
1091
1092#ifdef REALLOCATE_BITMAPSETS
1093
1094 /*
1095 * There's no guarantee that the repalloc returned a new pointer, so copy
1096 * and free unconditionally here.
1097 */
1098 a = bms_copy_and_free(a);
1099#endif
1100
1101 return a;
1102}
1103
1104/*
1105 * bms_int_members - like bms_intersect, but left input is recycled when
1106 * possible
1107 */
1108Bitmapset *
1109 bms_int_members(Bitmapset *a, const Bitmapset *b)
1110{
1111 int lastnonzero;
1112 int shortlen;
1113 int i;
1114
1115 Assert(bms_is_valid_set(a));
1116 Assert(bms_is_valid_set(b));
1117
1118 /* Handle cases where either input is NULL */
1119 if (a == NULL)
1120 return NULL;
1121 if (b == NULL)
1122 {
1123 pfree(a);
1124 return NULL;
1125 }
1126
1127 /* Intersect b into a; we need never copy */
1128 shortlen = Min(a->nwords, b->nwords);
1129 lastnonzero = -1;
1130 i = 0;
1131 do
1132 {
1133 a->words[i] &= b->words[i];
1134
1135 if (a->words[i] != 0)
1136 lastnonzero = i;
1137 } while (++i < shortlen);
1138
1139 /* If we computed an empty result, we must return NULL */
1140 if (lastnonzero == -1)
1141 {
1142 pfree(a);
1143 return NULL;
1144 }
1145
1146 /* get rid of trailing zero words */
1147 a->nwords = lastnonzero + 1;
1148
1149#ifdef REALLOCATE_BITMAPSETS
1150 a = bms_copy_and_free(a);
1151#endif
1152
1153 return a;
1154}
1155
1156/*
1157 * bms_del_members - delete members in 'a' that are set in 'b'. 'a' is
1158 * recycled when possible.
1159 */
1160Bitmapset *
1161 bms_del_members(Bitmapset *a, const Bitmapset *b)
1162{
1163 int i;
1164
1165 Assert(bms_is_valid_set(a));
1166 Assert(bms_is_valid_set(b));
1167
1168 /* Handle cases where either input is NULL */
1169 if (a == NULL)
1170 return NULL;
1171 if (b == NULL)
1172 {
1173#ifdef REALLOCATE_BITMAPSETS
1174 a = bms_copy_and_free(a);
1175#endif
1176
1177 return a;
1178 }
1179
1180 /* Remove b's bits from a; we need never copy */
1181 if (a->nwords > b->nwords)
1182 {
1183 /*
1184 * We'll never need to remove trailing zero words when 'a' has more
1185 * words than 'b'.
1186 */
1187 i = 0;
1188 do
1189 {
1190 a->words[i] &= ~b->words[i];
1191 } while (++i < b->nwords);
1192 }
1193 else
1194 {
1195 int lastnonzero = -1;
1196
1197 /* we may need to remove trailing zero words from the result. */
1198 i = 0;
1199 do
1200 {
1201 a->words[i] &= ~b->words[i];
1202
1203 /* remember the last non-zero word */
1204 if (a->words[i] != 0)
1205 lastnonzero = i;
1206 } while (++i < a->nwords);
1207
1208 /* check if 'a' has become empty */
1209 if (lastnonzero == -1)
1210 {
1211 pfree(a);
1212 return NULL;
1213 }
1214
1215 /* trim off any trailing zero words */
1216 a->nwords = lastnonzero + 1;
1217 }
1218
1219#ifdef REALLOCATE_BITMAPSETS
1220 a = bms_copy_and_free(a);
1221#endif
1222
1223 return a;
1224}
1225
1226/*
1227 * bms_join - like bms_union, but *either* input *may* be recycled
1228 */
1229Bitmapset *
1230 bms_join(Bitmapset *a, Bitmapset *b)
1231{
1232 Bitmapset *result;
1233 Bitmapset *other;
1234 int otherlen;
1235 int i;
1236
1237 Assert(bms_is_valid_set(a));
1238 Assert(bms_is_valid_set(b));
1239
1240 /* Handle cases where either input is NULL */
1241 if (a == NULL)
1242 {
1243#ifdef REALLOCATE_BITMAPSETS
1244 b = bms_copy_and_free(b);
1245#endif
1246
1247 return b;
1248 }
1249 if (b == NULL)
1250 {
1251#ifdef REALLOCATE_BITMAPSETS
1252 a = bms_copy_and_free(a);
1253#endif
1254
1255 return a;
1256 }
1257
1258 /* Identify shorter and longer input; use longer one as result */
1259 if (a->nwords < b->nwords)
1260 {
1261 result = b;
1262 other = a;
1263 }
1264 else
1265 {
1266 result = a;
1267 other = b;
1268 }
1269 /* And union the shorter input into the result */
1270 otherlen = other->nwords;
1271 i = 0;
1272 do
1273 {
1274 result->words[i] |= other->words[i];
1275 } while (++i < otherlen);
1276 if (other != result) /* pure paranoia */
1277 pfree(other);
1278
1279#ifdef REALLOCATE_BITMAPSETS
1280 result = bms_copy_and_free(result);
1281#endif
1282
1283 return result;
1284}
1285
1286/*
1287 * bms_next_member - find next member of a set
1288 *
1289 * Returns smallest member greater than "prevbit", or -2 if there is none.
1290 * "prevbit" must NOT be less than -1, or the behavior is unpredictable.
1291 *
1292 * This is intended as support for iterating through the members of a set.
1293 * The typical pattern is
1294 *
1295 * x = -1;
1296 * while ((x = bms_next_member(inputset, x)) >= 0)
1297 * process member x;
1298 *
1299 * Notice that when there are no more members, we return -2, not -1 as you
1300 * might expect. The rationale for that is to allow distinguishing the
1301 * loop-not-started state (x == -1) from the loop-completed state (x == -2).
1302 * It makes no difference in simple loop usage, but complex iteration logic
1303 * might need such an ability.
1304 */
1305int
1306 bms_next_member(const Bitmapset *a, int prevbit)
1307{
1308 int nwords;
1309 int wordnum;
1310 bitmapword mask;
1311
1312 Assert(bms_is_valid_set(a));
1313
1314 if (a == NULL)
1315 return -2;
1316 nwords = a->nwords;
1317 prevbit++;
1318 mask = (~(bitmapword) 0) << BITNUM(prevbit);
1319 for (wordnum = WORDNUM(prevbit); wordnum < nwords; wordnum++)
1320 {
1321 bitmapword w = a->words[wordnum];
1322
1323 /* ignore bits before prevbit */
1324 w &= mask;
1325
1326 if (w != 0)
1327 {
1328 int result;
1329
1330 result = wordnum * BITS_PER_BITMAPWORD;
1331 result += bmw_rightmost_one_pos(w);
1332 return result;
1333 }
1334
1335 /* in subsequent words, consider all bits */
1336 mask = (~(bitmapword) 0);
1337 }
1338 return -2;
1339}
1340
1341/*
1342 * bms_prev_member - find prev member of a set
1343 *
1344 * Returns largest member less than "prevbit", or -2 if there is none.
1345 * "prevbit" must NOT be more than one above the highest possible bit that can
1346 * be set in the Bitmapset at its current size.
1347 *
1348 * To ease finding the highest set bit for the initial loop, the special
1349 * prevbit value of -1 can be passed to have the function find the highest
1350 * valued member in the set.
1351 *
1352 * This is intended as support for iterating through the members of a set in
1353 * reverse. The typical pattern is
1354 *
1355 * x = -1;
1356 * while ((x = bms_prev_member(inputset, x)) >= 0)
1357 * process member x;
1358 *
1359 * Notice that when there are no more members, we return -2, not -1 as you
1360 * might expect. The rationale for that is to allow distinguishing the
1361 * loop-not-started state (x == -1) from the loop-completed state (x == -2).
1362 * It makes no difference in simple loop usage, but complex iteration logic
1363 * might need such an ability.
1364 */
1365
1366int
1367 bms_prev_member(const Bitmapset *a, int prevbit)
1368{
1369 int wordnum;
1370 int ushiftbits;
1371 bitmapword mask;
1372
1373 Assert(bms_is_valid_set(a));
1374
1375 /*
1376 * If set is NULL or if there are no more bits to the right then we've
1377 * nothing to do.
1378 */
1379 if (a == NULL || prevbit == 0)
1380 return -2;
1381
1382 /* Validate callers didn't give us something out of range */
1383 Assert(prevbit <= a->nwords * BITS_PER_BITMAPWORD);
1384 Assert(prevbit >= -1);
1385
1386 /* transform -1 to the highest possible bit we could have set */
1387 if (prevbit == -1)
1388 prevbit = a->nwords * BITS_PER_BITMAPWORD - 1;
1389 else
1390 prevbit--;
1391
1392 ushiftbits = BITS_PER_BITMAPWORD - (BITNUM(prevbit) + 1);
1393 mask = (~(bitmapword) 0) >> ushiftbits;
1394 for (wordnum = WORDNUM(prevbit); wordnum >= 0; wordnum--)
1395 {
1396 bitmapword w = a->words[wordnum];
1397
1398 /* mask out bits left of prevbit */
1399 w &= mask;
1400
1401 if (w != 0)
1402 {
1403 int result;
1404
1405 result = wordnum * BITS_PER_BITMAPWORD;
1406 result += bmw_leftmost_one_pos(w);
1407 return result;
1408 }
1409
1410 /* in subsequent words, consider all bits */
1411 mask = (~(bitmapword) 0);
1412 }
1413 return -2;
1414}
1415
1416/*
1417 * bms_hash_value - compute a hash key for a Bitmapset
1418 */
1419uint32
1420 bms_hash_value(const Bitmapset *a)
1421{
1422 Assert(bms_is_valid_set(a));
1423
1424 if (a == NULL)
1425 return 0; /* All empty sets hash to 0 */
1426 return DatumGetUInt32(hash_any((const unsigned char *) a->words,
1427 a->nwords * sizeof(bitmapword)));
1428}
1429
1430/*
1431 * bitmap_hash - hash function for keys that are (pointers to) Bitmapsets
1432 *
1433 * Note: don't forget to specify bitmap_match as the match function!
1434 */
1435uint32
1436 bitmap_hash(const void *key, Size keysize)
1437{
1438 Assert(keysize == sizeof(Bitmapset *));
1439 return bms_hash_value(*((const Bitmapset *const *) key));
1440}
1441
1442/*
1443 * bitmap_match - match function to use with bitmap_hash
1444 */
1445int
1446 bitmap_match(const void *key1, const void *key2, Size keysize)
1447{
1448 Assert(keysize == sizeof(Bitmapset *));
1449 return !bms_equal(*((const Bitmapset *const *) key1),
1450 *((const Bitmapset *const *) key2));
1451}
#define BITMAPSET_SIZE(nwords)
Definition: bitmapset.c:50
Bitmapset * bms_replace_members(Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:972
Bitmapset * bms_difference(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:346
int bms_prev_member(const Bitmapset *a, int prevbit)
Definition: bitmapset.c:1367
Bitmapset * bms_make_singleton(int x)
Definition: bitmapset.c:216
Bitmapset * bms_int_members(Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:1109
Bitmapset * bms_intersect(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:292
uint32 bitmap_hash(const void *key, Size keysize)
Definition: bitmapset.c:1436
#define WORDNUM(x)
Definition: bitmapset.c:47
bool bms_equal(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:142
BMS_Comparison bms_subset_compare(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:445
int bms_next_member(const Bitmapset *a, int prevbit)
Definition: bitmapset.c:1306
uint32 bms_hash_value(const Bitmapset *a)
Definition: bitmapset.c:1420
Bitmapset * bms_del_members(Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:1161
Bitmapset * bms_add_range(Bitmapset *a, int lower, int upper)
Definition: bitmapset.c:1019
Bitmapset * bms_del_member(Bitmapset *a, int x)
Definition: bitmapset.c:868
bool bms_is_subset(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:412
int bms_singleton_member(const Bitmapset *a)
Definition: bitmapset.c:672
void bms_free(Bitmapset *a)
Definition: bitmapset.c:239
int bms_num_members(const Bitmapset *a)
Definition: bitmapset.c:751
bool bms_is_member(int x, const Bitmapset *a)
Definition: bitmapset.c:510
Bitmapset * bms_add_member(Bitmapset *a, int x)
Definition: bitmapset.c:815
Bitmapset * bms_add_members(Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:917
#define BITNUM(x)
Definition: bitmapset.c:48
Bitmapset * bms_union(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:251
#define HAS_MULTIPLE_ONES(x)
Definition: bitmapset.c:72
int bitmap_match(const void *key1, const void *key2, Size keysize)
Definition: bitmapset.c:1446
BMS_Membership bms_membership(const Bitmapset *a)
Definition: bitmapset.c:781
int bms_member_index(Bitmapset *a, int x)
Definition: bitmapset.c:539
bool bms_overlap(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:582
int bms_compare(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:183
bool bms_get_singleton_member(const Bitmapset *a, int *member)
Definition: bitmapset.c:715
Bitmapset * bms_join(Bitmapset *a, Bitmapset *b)
Definition: bitmapset.c:1230
bool bms_nonempty_difference(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:641
Bitmapset * bms_copy(const Bitmapset *a)
Definition: bitmapset.c:122
bool bms_overlap_list(const Bitmapset *a, const List *b)
Definition: bitmapset.c:608
#define bmw_rightmost_one_pos(w)
Definition: bitmapset.h:79
#define bmw_leftmost_one_pos(w)
Definition: bitmapset.h:78
BMS_Comparison
Definition: bitmapset.h:61
@ BMS_DIFFERENT
Definition: bitmapset.h:65
@ BMS_SUBSET1
Definition: bitmapset.h:63
@ BMS_EQUAL
Definition: bitmapset.h:62
@ BMS_SUBSET2
Definition: bitmapset.h:64
BMS_Membership
Definition: bitmapset.h:70
@ BMS_SINGLETON
Definition: bitmapset.h:72
@ BMS_EMPTY_SET
Definition: bitmapset.h:71
@ BMS_MULTIPLE
Definition: bitmapset.h:73
uint32 bitmapword
Definition: bitmapset.h:44
#define BITS_PER_BITMAPWORD
Definition: bitmapset.h:43
#define bmw_popcount(w)
Definition: bitmapset.h:80
#define Min(x, y)
Definition: c.h:1003
#define unlikely(x)
Definition: c.h:402
uint32_t uint32
Definition: c.h:538
size_t Size
Definition: c.h:610
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:226
static Datum hash_any(const unsigned char *k, int keylen)
Definition: hashfn.h:31
Assert(PointerIsAligned(start, uint64))
b
int b
Definition: isn.c:74
x
int x
Definition: isn.c:75
a
int a
Definition: isn.c:73
i
int i
Definition: isn.c:77
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:1610
void pfree(void *pointer)
Definition: mcxt.c:1594
void * palloc0(Size size)
Definition: mcxt.c:1395
void * palloc(Size size)
Definition: mcxt.c:1365
#define IsA(nodeptr, _type_)
Definition: nodes.h:164
Datum lower(PG_FUNCTION_ARGS)
Definition: oracle_compat.c:49
Datum upper(PG_FUNCTION_ARGS)
Definition: oracle_compat.c:80
#define NIL
Definition: pg_list.h:68
#define lfirst_int(lc)
Definition: pg_list.h:173
static uint32 DatumGetUInt32(Datum X)
Definition: postgres.h:232
c
char * c
Definition: preproc-cursor.c:31
int nwords
Definition: bitmapset.h:54
bitmapword words[FLEXIBLE_ARRAY_MEMBER]
Definition: bitmapset.h:55
Definition: pg_list.h:54
Definition: pg_list.h:46

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