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gh-149427: Improve performance of re.compile() for patterns with character ranges #149428

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gh-149427: Improve performance of re.compile() for patterns with character ranges #149428

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d765dc1
re._compiler: bytearray slice fill in _optimize_charset
eendebakpt May 5, 2026
e7ca3ef
blurb
eendebakpt May 5, 2026
56e25cd
review comment
eendebakpt May 19, 2026
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Merge branch 'main' into regex_compile_charset_memcpy
eendebakpt Jun 1, 2026
7ce4add
Merge remote-tracking branch 'origin/main' into regex_compile_charset…
eendebakpt Jul 1, 2026
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Apply suggestion from @serhiy-storchaka
eendebakpt Jul 5, 2026
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Merge branch 'main' into regex_compile_charset_memcpy
eendebakpt Jul 5, 2026
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11 changes: 8 additions & 3 deletions Lib/re/_optimizer.py
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Original file line number Diff line number Diff line change
Expand Up @@ -108,7 +108,9 @@ def _optimize_charset_segment(charset, iscased=None, fixup=None, fixes=None,
else:
charmap[av] = 1
elif op is RANGE:
r = range(av[0], av[1]+1)
start, end = av
end += 1
r = range(start, end)
if fixup: # IGNORECASE and not LOCALE
if fixes:
for i in map(fixup, r):
Expand All @@ -122,8 +124,11 @@ def _optimize_charset_segment(charset, iscased=None, fixup=None, fixes=None,
if not hascased:
hascased = any(map(iscased, r))
else:
for i in r:
charmap[i] = 1
if end > len(charmap):
if len(charmap) == 0x10000 and start < 0x10000:
charmap[start:0x10000] = b'\x01' * (0x10000 - start)
raise IndexError
charmap[start:end] = b'\x01' * (end - start)
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elif op is NEGATE:
out.append((op, av))
elif op is CATEGORY and _allow_anyall and tail and (CATEGORY, CH_NEGATE[av]) in tail:
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2026-05-05-18-39-52.gh-issue-149427.0ggedQ.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Speed up :func:`re.compile` of patterns with character ranges by replacing
the per-byte loop in :mod:`!re._compiler` with a single bytearray slice
fill.
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