mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-11-25 04:34:37 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 11

Issue #5812: make Fraction('1e-6') valid. Backport of r71806.

Browse source
This commit is contained in:
Mark Dickinson 2009-04-22 18:15:25 +00:00
parent ebafbb705c
commit 8100bd8431
4 changed files with 46 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

45
Lib/fractions.py
View file

@ -30,13 +30,14 @@ _RATIONAL_FORMAT = re.compile(r"""
(?P<sign>[-+]?) # an optional sign, then
(?=\d|\.\d) # lookahead for digit or .digit
(?P<num>\d*) # numerator (possibly empty)
(?: # followed by an optional
/(?P<denom>\d+) # / and denominator
(?: # followed by
(?:/(?P<denom>\d+))? # an optional denominator
| # or
\.(?P<decimal>\d*) # decimal point and fractional part
)?
(?:\.(?P<decimal>\d*))? # an optional fractional part
(?:E(?P<exp>[-+]?\d+))? # and optional exponent
)
\s*\Z # and optional whitespace to finish
""", re.VERBOSE)
""", re.VERBOSE | re.IGNORECASE)
class Fraction(Rational):
@ -67,22 +68,28 @@ class Fraction(Rational):
if type(numerator) not in (int, long) and denominator == 1:
if isinstance(numerator, basestring):
# Handle construction from strings.
input = numerator
m = _RATIONAL_FORMAT.match(input)
m = _RATIONAL_FORMAT.match(numerator)
if m is None:
raise ValueError('Invalid literal for Fraction: %r' % input)
numerator = m.group('num')
decimal = m.group('decimal')
if decimal:
# The literal is a decimal number.
numerator = int(numerator + decimal)
denominator = 10**len(decimal)
raise ValueError('Invalid literal for Fraction: %r' %
numerator)
numerator = int(m.group('num') or '0')
denom = m.group('denom')
if denom:
denominator = int(denom)
else:
# The literal is an integer or fraction.
numerator = int(numerator)
# Default denominator to 1.
denominator = int(m.group('denom') or 1)
denominator = 1
decimal = m.group('decimal')
if decimal:
scale = 10**len(decimal)
numerator = numerator * scale + int(decimal)
denominator *= scale
exp = m.group('exp')
if exp:
exp = int(exp)
if exp >= 0:
numerator *= 10**exp
else:
denominator *= 10**-exp
if m.group('sign') == '-':
numerator = -numerator