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gh-140036: _pydecimal: avoid slow exponentiation in floor division #140044

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gh-140036: _pydecimal: avoid slow exponentiation in floor division #140044

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ee617bd
_pydecimal: avoid slow exponentiation in floor division
picnixz Oct 13, 2025
329c31a
refine `q < 10**context.prec` checks
picnixz Oct 14, 2025
103fe1e
_pydecimal: add helpers for computing len(str(q)) < a
picnixz Oct 26, 2025
efbdc0a
_pydecimal: use helpers for computing len(str(q)) < a
picnixz Oct 26, 2025
9377ab6
_pydecimal: add tests for unbounded contexts
picnixz Oct 26, 2025
23494fb
Apply suggestions from code review
picnixz Nov 7, 2025
6b55711
address review
picnixz Nov 9, 2025
49d5b0d
reformulate comment
picnixz Nov 9, 2025
ea3e499
Update Lib/_pydecimal.py
picnixz Nov 9, 2025
b1c24b7
add test for _is_less_than_pow10a_use_str() slow path
picnixz Nov 9, 2025
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@picnixz
picnixz committed Nov 9, 2025
commit 49d5b0d98da7c033842db01ce4c233cd5455282d
5 changes: 2 additions & 3 deletions Lib/_pydecimal.py
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Expand Up @@ -465,9 +465,8 @@ def _tento(n):
def _is_less_than_pow10a_use_str(q, a):
"""Try to efficiently check len(str(q)) <= a, or equivalently q < 10**a.

If it is not possible to efficiently compute the comparison, str(q) is
explicitly computed. str(q) may also be computed for cases that cannot
be optimized.
If the comparison cannot be obtained from q.bit_length(),
then str(q) is explicitly computed and may raise ValueError.

Return (len(str(q)) <= a, None) or (len(str(q)) <= a, str(q)).
"""
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