Skip to content

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

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
eendebakpt wants to merge 2 commits into
base: main
Choose a base branch
from
+8 −2
Open

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

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
d765dc1
re._compiler: bytearray slice fill in _optimize_charset
eendebakpt May 5, 2026
e7ca3ef
blurb
eendebakpt May 5, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 5 additions & 2 deletions Lib/re/_compiler.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -280,8 +280,11 @@ def _optimize_charset(charset, iscased=None, fixup=None, fixes=None):
if not hascased:
hascased = any(map(iscased, r))
else:
for i in r:
charmap[i] = 1
end = av[1] + 1
if end > len(charmap):
# Trigger the IndexError growth path below.
raise IndexError
charmap[av[0]:end] = b'\x01' * (end - av[0])
elif op is NEGATE:
out.append((op, av))
elif op is CATEGORY and tail and (CATEGORY, CH_NEGATE[av]) in tail:
Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2026-05-05-18-39-52.gh-issue-149427.0ggedQ.rst
View file
Open in desktop
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.
Loading