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gh-91851: Micro optimizations for arithmetic between Fractions (#25518) 

Adapted from
https://github.com/python/cpython/pull/24779/commits/046c84e8f9

This makes arithmetic between Fractions with small components
just as fast as before python/cpython#24779, at some expense of
mixed arithmetic (e.g. Fraction + int).
This commit is contained in:
Sergey B Kirpichev 2023-01-08 11:34:20 +03:00 committed by GitHub
parent 6d3bc4a795
commit 909982e82a
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 13 additions and 10 deletions
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22
Lib/fractions.py
View File

@ -395,8 +395,10 @@ class doesn't subclass a concrete type, there's no
"""
def forward(a, b):
if isinstance(b, (int, Fraction)):
if isinstance(b, Fraction):
return monomorphic_operator(a, b)
elif isinstance(b, int):
return monomorphic_operator(a, Fraction(b))
elif isinstance(b, float):
return fallback_operator(float(a), b)
elif isinstance(b, complex):
@ -409,7 +411,7 @@ def forward(a, b):
def reverse(b, a):
if isinstance(a, numbers.Rational):
# Includes ints.
return monomorphic_operator(a, b)
return monomorphic_operator(Fraction(a), b)
elif isinstance(a, numbers.Real):
return fallback_operator(float(a), float(b))
elif isinstance(a, numbers.Complex):
@ -491,8 +493,8 @@ def reverse(b, a):
def _add(a, b):
"""a + b"""
na, da = a.numerator, a.denominator
nb, db = b.numerator, b.denominator
na, da = a._numerator, a._denominator
nb, db = b._numerator, b._denominator
g = math.gcd(da, db)
if g == 1:
return Fraction(na * db + da * nb, da * db, _normalize=False)
@ -507,8 +509,8 @@ def _add(a, b):
def _sub(a, b):
"""a - b"""
na, da = a.numerator, a.denominator
nb, db = b.numerator, b.denominator
na, da = a._numerator, a._denominator
nb, db = b._numerator, b._denominator
g = math.gcd(da, db)
if g == 1:
return Fraction(na * db - da * nb, da * db, _normalize=False)
@ -523,8 +525,8 @@ def _sub(a, b):
def _mul(a, b):
"""a * b"""
na, da = a.numerator, a.denominator
nb, db = b.numerator, b.denominator
na, da = a._numerator, a._denominator
nb, db = b._numerator, b._denominator
g1 = math.gcd(na, db)
if g1 > 1:
na //= g1
@ -540,8 +542,8 @@ def _mul(a, b):
def _div(a, b):
"""a / b"""
# Same as _mul(), with inversed b.
na, da = a.numerator, a.denominator
nb, db = b.numerator, b.denominator
na, da = a._numerator, a._denominator
nb, db = b._numerator, b._denominator
g1 = math.gcd(na, nb)
if g1 > 1:
na //= g1

1
Misc/NEWS.d/next/Library/2022-04-23-08-12-14.gh-issue-91851.Jd47V6.rst Normal file
View File

@ -0,0 +1 @@
Optimize the :class:`~fractions.Fraction` arithmetics for small components.