Author: facundo.batista Date: Fri Aug 31 01:55:28 2007 New Revision: 57782 Modified: python/branches/decimal-branch/Lib/decimal.py python/branches/decimal-branch/Lib/test/test_decimal.py Log: Added the new rounding mode, ROUND_05UP, to decimal.py implementation) and to the test_decimal.py to be able to test it. Fixed also that if context._clamp=1 then the maximum length of a NaN payload should be context.prec-1, not context.prec. And some bugs in division (essentially, it makes sure that any result always goes through fix where appropriate, so that folddown always occurs if necessary). Thanks Mark Dickinson. Modified: python/branches/decimal-branch/Lib/decimal.py ============================================================================== --- python/branches/decimal-branch/Lib/decimal.py (original) +++ python/branches/decimal-branch/Lib/decimal.py Fri Aug 31 01:55:28 2007 @@ -128,7 +128,7 @@ # Constants for use in setting up contexts 'ROUND_DOWN', 'ROUND_HALF_UP', 'ROUND_HALF_EVEN', 'ROUND_CEILING', - 'ROUND_FLOOR', 'ROUND_UP', 'ROUND_HALF_DOWN', + 'ROUND_FLOOR', 'ROUND_UP', 'ROUND_HALF_DOWN', 'ROUND_05UP', # Functions for manipulating contexts 'setcontext', 'getcontext', 'localcontext' @@ -144,6 +144,7 @@ ROUND_FLOOR = 'ROUND_FLOOR' ROUND_UP = 'ROUND_UP' ROUND_HALF_DOWN = 'ROUND_HALF_DOWN' +ROUND_05UP = 'ROUND_05UP' # Rounding decision (not part of the public API) NEVER_ROUND = 'NEVER_ROUND' # Round in division (non-divmod), sqrt ONLY @@ -348,7 +349,8 @@ def handle(self, context, sign, *args): if context.rounding in (ROUND_HALF_UP, ROUND_HALF_EVEN, - ROUND_HALF_DOWN, ROUND_UP): + ROUND_HALF_DOWN, ROUND_UP, + ROUND_05UP): return Infsign[sign] if sign == 0: if context.rounding == ROUND_CEILING: @@ -1200,6 +1202,8 @@ if context is None: context = getcontext() + shouldround = context._rounding_decision == ALWAYS_ROUND + sign = self._sign ^ other._sign if self._is_special or other._is_special: @@ -1231,7 +1235,10 @@ if other._isinfinity(): if divmod: - return (Decimal((sign, (0,), 0)), Decimal(self)) + otherside = Decimal(self) + if shouldround and (divmod == 1 or divmod == 3): + otherside = otherside._fix(context) + return (Decimal((sign, (0,), 0)), otherside) context._raise_error(Clamped, 'Division by infinity') return Decimal((sign, (0,), context.Etiny())) @@ -1243,17 +1250,14 @@ if not self: if divmod: - otherside = Decimal(self) - otherside._exp = min(self._exp, other._exp) + otherside = Decimal((self._sign, (0,), min(self._exp, other._exp))) + if shouldround and (divmod == 1 or divmod == 3): + otherside = otherside._fix(context) return (Decimal((sign, (0,), 0)), otherside) exp = self._exp - other._exp - if exp < context.Etiny(): - exp = context.Etiny() - context._raise_error(Clamped, '0e-x / y') - if exp > context.Emax: - exp = context.Emax - context._raise_error(Clamped, '0e+x / y') - return Decimal( (sign, (0,), exp) ) + ans = Decimal((sign, (0,), exp)) + ans = ans._fix(context) + return ans if not other: if divmod: @@ -1262,7 +1266,6 @@ return context._raise_error(DivisionByZero, 'x / 0', sign) # OK, so neither = 0, INF or NaN - shouldround = context._rounding_decision == ALWAYS_ROUND # If we're dividing into ints, and self < other, stop. # self.__abs__(0) does not round. @@ -1301,7 +1304,7 @@ exp = min(self._exp, other._exp) otherside = otherside._rescale(exp, context=context, watchexp=0) context._regard_flags(*frozen) - if shouldround: + if shouldround and (divmod == 1 or divmod == 3): otherside = otherside._fix(context) return (Decimal(res), otherside) @@ -1325,21 +1328,6 @@ op1.int *= 10 op1.exp -= 1 - if res.exp == 0 and divmod and op2.int > op1.int: - # Solves an error in precision. Same as a previous block. - - if res.int >= prec_limit and shouldround: - return context._raise_error(DivisionImpossible) - otherside = Decimal(op1) - frozen = context._ignore_all_flags() - - exp = min(self._exp, other._exp) - otherside = otherside._rescale(exp, context=context) - - context._regard_flags(*frozen) - - return (Decimal(res), otherside) - ans = Decimal(res) if shouldround: ans = ans._fix(context) @@ -1513,9 +1501,13 @@ def _fix_nan(self, context): """Decapitate the payload of a NaN to fit the context""" payload = self._int - if len(payload) > context.prec: - pos = -context.prec - while payload[pos] == 0 and pos < -1: + + # maximum length of payload is precision if _clamp=0, + # precision-1 if _clamp=1. + max_payload_len = context.prec - context._clamp + if len(payload) > max_payload_len: + pos = len(payload)-max_payload_len + while pos < len(payload) and payload[pos] == 0: pos += 1 payload = payload[pos:] return Decimal((self._sign, payload, self._exp)) @@ -1791,6 +1783,13 @@ else: return self._round_up(prec, expdiff, context) + def _round_05up(self, prec, expdiff, context): + """Round down unless digit prec-1 is 0 or 5.""" + if self._int[prec-1] in (0, 5): + return self._round_up(prec, expdiff, context) + else: + return self._round_down(prec, expdiff, context) + def fma(self, other, third, context=None): """Fused multiply-add. @@ -3754,7 +3753,7 @@ def create_decimal(self, num='0'): """Creates a new Decimal instance but using self as context.""" d = Decimal(num, context=self) - if d._isnan() and len(d._int) > self.prec: + if d._isnan() and len(d._int) > self.prec - self._clamp: return self._raise_error(ConversionSyntax, "diagnostic info too long in NaN") return d._fix(self) Modified: python/branches/decimal-branch/Lib/test/test_decimal.py ============================================================================== --- python/branches/decimal-branch/Lib/test/test_decimal.py (original) +++ python/branches/decimal-branch/Lib/test/test_decimal.py Fri Aug 31 01:55:28 2007 @@ -95,7 +95,8 @@ 'half_down' : ROUND_HALF_DOWN, 'half_even' : ROUND_HALF_EVEN, 'half_up' : ROUND_HALF_UP, - 'up' : ROUND_UP} + 'up' : ROUND_UP, + '05up' : ROUND_05UP} # Name adapter to be able to change the Decimal and Context # interface without changing the test files from Cowlishaw