gh-134953: Make the True/False/None check more efficient #138931
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| ZERO_WIDTH_BRACKET = re.compile(r"\x01.*?\x02") | ||
| ZERO_WIDTH_TRANS = str.maketrans({"\x01": "", "\x02": ""}) | ||
| IDENTIFIERS_AFTER = {"def", "class"} | ||
| KEYWORD_CONSTANTS = {"True", "False", "None"} |
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| KEYWORD_CONSTANTS = {"True", "False", "None"} | |
| KEYWORD_CONSTANTS = frozenset({"True", "False", "None"}) |
Is even faster.
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The compiler already does this automatically:
>>> def foo():
... KEYWORD_CONSTANTS = {"True", "False", "None"}
...
>>> foo.__code__.co_consts
(None, frozenset({'False', 'True', 'None'}))
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The compiler only does that for function locals, right? A module variable could be mutated from other modules.
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@auscompgeek You are right, for module level variables the optimization is not performed, so KEYWORD_CONSTANTS stays a set. For the free-threading build the performance difference is measurable:
Python 3.15.0a0 free-threading build (heads/main-dirty:2a54acf3c3d, Sep 1 2025, 14:33:50) [MSC v.1939 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import timeit
>>> timeit.timeit('[10 in s for ii in range(100)]', setup='from _pyrepl.utils import KEYWORD_CONSTANTS as s; f = frozenset(s)')
8.864965499844402
>>> timeit.timeit('[10 in f for ii in range(100)]', setup='from _pyrepl.utils import KEYWORD_CONSTANTS as s; f = frozenset(s)')
8.371516299899668
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@eendebakpt I'll accept a PR to wrap all global sets in _pyrepl.utils as frozensets. There's quite a few of them.
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I created a bit more general issue: #139003. For _pyrepl I'll make a PR.
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Thanks @ambv for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14. |
…nGH-138931) (cherry picked from commit 811acc8) Co-authored-by: Łukasz Langa <lukasz@langa.pl>
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GH-138939 is a backport of this pull request to the 3.14 branch. |
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