diff options
Diffstat (limited to 'src/backend/nodes/bitmapset.c')
| -rw-r--r-- | src/backend/nodes/bitmapset.c | 46 |
1 files changed, 45 insertions, 1 deletions
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c index 733fe3cf2a0..edcd19a4fd7 100644 --- a/src/backend/nodes/bitmapset.c +++ b/src/backend/nodes/bitmapset.c @@ -173,6 +173,50 @@ bms_equal(const Bitmapset *a, const Bitmapset *b) } /* + * bms_compare - qsort-style comparator for bitmapsets + * + * This guarantees to report values as equal iff bms_equal would say they are + * equal. Otherwise, the highest-numbered bit that is set in one value but + * not the other determines the result. (This rule means that, for example, + * {6} is greater than {5}, which seems plausible.) + */ +int +bms_compare(const Bitmapset *a, const Bitmapset *b) +{ + int shortlen; + int i; + + /* Handle cases where either input is NULL */ + if (a == NULL) + return bms_is_empty(b) ? 0 : -1; + else if (b == NULL) + return bms_is_empty(a) ? 0 : +1; + /* Handle cases where one input is longer than the other */ + shortlen = Min(a->nwords, b->nwords); + for (i = shortlen; i < a->nwords; i++) + { + if (a->words[i] != 0) + return +1; + } + for (i = shortlen; i < b->nwords; i++) + { + if (b->words[i] != 0) + return -1; + } + /* Process words in common */ + i = shortlen; + while (--i >= 0) + { + bitmapword aw = a->words[i]; + bitmapword bw = b->words[i]; + + if (aw != bw) + return (aw > bw) ? +1 : -1; + } + return 0; +} + +/* * bms_make_singleton - build a bitmapset containing a single member */ Bitmapset * @@ -838,7 +882,7 @@ bms_add_range(Bitmapset *a, int lower, int upper) if (lwordnum == uwordnum) { a->words[lwordnum] |= ~(bitmapword) (((bitmapword) 1 << lbitnum) - 1) - & (~(bitmapword) 0) >> ushiftbits; + & (~(bitmapword) 0) >> ushiftbits; } else { |