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SF patch #1053375.

Browse source 
(Contributed by Facundo Batista.)

Code simplification by eliminating the unnecessary and error-prone
convolutions for the previously weird sign convention in _WorkRep().
Makes the code more understandable, more reliable, and a bit faster.
This commit is contained in:
Raymond Hettinger 2004-10-27 06:21:46 +00:00
parent 7afa64e260
commit 17931de110
1 changed files with 18 additions and 63 deletions
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81
Lib/decimal.py
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@ -477,10 +477,7 @@ class Decimal(object):
# From an internal working value # From an internal working value
if isinstance(value, _WorkRep): if isinstance(value, _WorkRep):
if value.sign == 1: self._sign = value.sign
self._sign = 0
else:
self._sign = 1
self._int = tuple(map(int, str(value.int))) self._int = tuple(map(int, str(value.int)))
self._exp = int(value.exp) self._exp = int(value.exp)
return self return self
@ -955,32 +952,30 @@ class Decimal(object):
op1, op2 = _normalize(op1, op2, shouldround, context.prec) op1, op2 = _normalize(op1, op2, shouldround, context.prec)
result = _WorkRep() result = _WorkRep()
if op1.sign != op2.sign: if op1.sign != op2.sign:
diff = cmp(abs(op1), abs(op2))
# Equal and opposite # Equal and opposite
if diff == 0: if op1.int == op2.int:
if exp < context.Etiny(): if exp < context.Etiny():
exp = context.Etiny() exp = context.Etiny()
context._raise_error(Clamped) context._raise_error(Clamped)
return Decimal((negativezero, (0,), exp)) return Decimal((negativezero, (0,), exp))
if diff < 0: if op1.int < op2.int:
op1, op2 = op2, op1 op1, op2 = op2, op1
#OK, now abs(op1) > abs(op2) #OK, now abs(op1) > abs(op2)
if op1.sign == -1: if op1.sign == 1:
result.sign = -1 result.sign = 1
op1.sign, op2.sign = op2.sign, op1.sign op1.sign, op2.sign = op2.sign, op1.sign
else: else:
result.sign = 1 result.sign = 0
#So we know the sign, and op1 > 0. #So we know the sign, and op1 > 0.
elif op1.sign == -1: elif op1.sign == 1:
result.sign = -1
op1.sign, op2.sign = (1, 1)
else:
result.sign = 1 result.sign = 1
op1.sign, op2.sign = (0, 0)
else:
result.sign = 0
#Now, op1 > abs(op2) > 0 #Now, op1 > abs(op2) > 0
if op2.sign == 1: if op2.sign == 0:
result.int = op1.int + op2.int result.int = op1.int + op2.int
else: else:
result.int = op1.int - op2.int result.int = op1.int - op2.int
@ -1214,11 +1209,6 @@ class Decimal(object):
#Don't round the mod part, if we don't need it. #Don't round the mod part, if we don't need it.
return (Decimal( (sign, (0,), 0) ), Decimal(self)) return (Decimal( (sign, (0,), 0) ), Decimal(self))
if sign:
sign = -1
else:
sign = 1
adjust = 0
op1 = _WorkRep(self) op1 = _WorkRep(self)
op2 = _WorkRep(other) op2 = _WorkRep(other)
op1, op2, adjust = _adjust_coefficients(op1, op2) op1, op2, adjust = _adjust_coefficients(op1, op2)
@ -1238,8 +1228,7 @@ class Decimal(object):
frozen = context._ignore_all_flags() frozen = context._ignore_all_flags()
exp = min(self._exp, other._exp) exp = min(self._exp, other._exp)
otherside = otherside._rescale(exp, context=context, otherside = otherside._rescale(exp, context=context, watchexp=0)
watchexp=0)
context._regard_flags(*frozen) context._regard_flags(*frozen)
if shouldround: if shouldround:
otherside = otherside._fix(context) otherside = otherside._fix(context)
@ -2769,7 +2758,7 @@ class Context(object):
class _WorkRep(object): class _WorkRep(object):
__slots__ = ('sign','int','exp') __slots__ = ('sign','int','exp')
# sign: -1 None 1 # sign: 0 or 1
# int: int or long # int: int or long
# exp: None, int, or string # exp: None, int, or string
@ -2778,17 +2767,15 @@ class _WorkRep(object):
self.sign = None self.sign = None
self.int = 0 self.int = 0
self.exp = None self.exp = None
if isinstance(value, Decimal): elif isinstance(value, Decimal):
if value._sign: self.sign = value._sign
self.sign = -1
else:
self.sign = 1
cum = 0 cum = 0
for digit in value._int: for digit in value._int:
cum = cum * 10 + digit cum = cum * 10 + digit
self.int = cum self.int = cum
self.exp = value._exp self.exp = value._exp
if isinstance(value, tuple): else:
# assert isinstance(value, tuple)
self.sign = value[0] self.sign = value[0]
self.int = value[1] self.int = value[1]
self.exp = value[2] self.exp = value[2]
@ -2798,38 +2785,6 @@ class _WorkRep(object):
__str__ = __repr__ __str__ = __repr__
def __neg__(self):
if self.sign == 1:
return _WorkRep( (-1, self.int, self.exp) )
else:
return _WorkRep( (1, self.int, self.exp) )
def __abs__(self):
if self.sign == -1:
return -self
else:
return self
def __cmp__(self, other):
if self.exp != other.exp:
raise ValueError("Operands not normalized: %r, %r" % (self, other))
if self.sign != other.sign:
if self.sign == -1:
return -1
else:
return 1
if self.sign == -1:
direction = -1
else:
direction = 1
int1 = self.int
int2 = other.int
if int1 > int2:
return direction * 1
if int1 < int2:
return direction * -1
return 0
def _normalize(op1, op2, shouldround = 0, prec = 0): def _normalize(op1, op2, shouldround = 0, prec = 0):