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gh-153044: Auto-possessify greedy repeats with a disjoint continuation #153048

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gh-153044: Auto-possessify greedy repeats with a disjoint continuation #153048

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c6b58ec
gh-153044: Auto-possessify greedy repeats with a disjoint continuation
serhiy-storchaka Jun 23, 2026
6b33a9c
gh-153044: Note the flag-context invariant of the complement rule
serhiy-storchaka Jul 4, 2026
4184a6a
gh-153044: Cap the size of a follower set
serhiy-storchaka Jul 5, 2026
ba9c881
gh-153044: Test each follower-set growth guard at its limit
serhiy-storchaka Jul 5, 2026
7868451
gh-153044: Bound the follower-scan recursion
serhiy-storchaka Jul 5, 2026
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6 changes: 6 additions & 0 deletions Doc/whatsnew/3.16.rst
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Expand Up @@ -423,6 +423,12 @@ re
(Contributed by Serhiy Storchaka in :gh:`152033` and Pieter Eendebak in
:gh:`152056`.)

* A greedy repeat is now compiled as possessive when the repeated characters
and the characters that can follow it are provably disjoint (for example
``\d+\.`` is compiled as if it were ``\d++\.``), which makes failing and
heavily backtracking matches severalfold faster.
(Contributed by Serhiy Storchaka in :gh:`153044`.)

module_name
-----------

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2 changes: 1 addition & 1 deletion Lib/re/_compiler.py
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Expand Up @@ -221,7 +221,7 @@ def _code(p, flags):
flags = p.state.flags | flags

# run the optimizer passes over the parsed pattern
optimize(p)
optimize(p, flags)

code = []

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