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Make regex "max_chr" depend on encoding, not provider.

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The regex mechanism scans through the first "max_chr" character values
to cache character property ranges (isalpha, etc.). For single-byte
encodings, there's no sense in scanning beyond UCHAR_MAX; but for
UTF-8 it makes sense to cache higher code point values (though not all
of them; only up to MAX_SIMPLE_CHR).

Prior to 5a38104b36, the logic about how many character values to scan
was based on the pg_regex_strategy, which was dependent on the
provider. Commit 5a38104b36 preserved that logic exactly, allowing
different providers to define the "max_chr".

Now, change it to depend only on the encoding and whether
ctype_is_c. For this specific calculation, distinguishing between
providers creates more complexity than it's worth.

Discussion: https://postgr.es/m/450ceb6260cad30d7afdf155d991a9caafee7c0d.camel@j-davis.com
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
This commit is contained in:
Jeff Davis
2025-12-01 11:06:17 -08:00
parent 99cd8890be
commit 19b966243c
3 changed files with 10 additions and 16 deletions
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18
src/backend/regex/regc_pg_locale.c
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@@ -320,16 +320,18 @@ regc_ctype_get_cache(regc_wc_probefunc probefunc, int cclasscode)
max_chr = (pg_wchar) MAX_SIMPLE_CHR;
#endif
}
else if (GetDatabaseEncoding() == PG_UTF8)
{
max_chr = (pg_wchar) MAX_SIMPLE_CHR;
}
else
{
if (pg_regex_locale->ctype->max_chr != 0 &&
pg_regex_locale->ctype->max_chr <= MAX_SIMPLE_CHR)
{
max_chr = pg_regex_locale->ctype->max_chr;
pcc->cv.cclasscode = -1;
}
else
max_chr = (pg_wchar) MAX_SIMPLE_CHR;
#if MAX_SIMPLE_CHR >= UCHAR_MAX
max_chr = (pg_wchar) UCHAR_MAX;
pcc->cv.cclasscode = -1;
#else
max_chr = (pg_wchar) MAX_SIMPLE_CHR;
#endif
}
/*