Merged revisions 59107-59186 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

(Note: some conflicts in the PCbuild9 directory reverted.  Sorry Christian!)

........
  r59120 | christian.heimes | 2007-11-22 03:21:16 -0800 (Thu, 22 Nov 2007) | 3 lines

  Backport of the PCbuild9 directory from the py3k branch.
  I've finished the last task for the PCbuild9 directory today. I don't think there is much left to do. Now you can all play around with the shiny new VS 2008 and try the PGO builds. I was able to get a speed improvement of about 10% on py3k.
  Have fun! :)
........
  r59126 | brett.cannon | 2007-11-22 16:06:51 -0800 (Thu, 22 Nov 2007) | 2 lines

  Fix a bug in the test for using __loader__.get_data().
........
  r59131 | christian.heimes | 2007-11-22 23:05:03 -0800 (Thu, 22 Nov 2007) | 1 line

  Backport of PCbuild9 fixes from py3k r59130
........
  r59132 | christian.heimes | 2007-11-23 01:10:36 -0800 (Fri, 23 Nov 2007) | 2 lines

  Applied patch #1754273 and #1754271 from Thomas Glee
  The patches are adding deprecation warnings for back ticks and <>
........
  r59133 | christian.heimes | 2007-11-23 04:12:02 -0800 (Fri, 23 Nov 2007) | 2 lines

  Fixed problems in the last commit. Filenames and line numbers weren't reported correctly.
  Backquotes still don't report the correct file. The AST nodes only contain the line number but not the file name.
........
  r59134 | christian.heimes | 2007-11-23 04:16:35 -0800 (Fri, 23 Nov 2007) | 1 line

  How did the comment get there?
........
  r59135 | christian.heimes | 2007-11-23 05:25:31 -0800 (Fri, 23 Nov 2007) | 1 line

  And yet another fix for the patch. Paul Moore has send me a note that I've missed a declaration. The additional code has moved the declaration in the middle of the block.
........
  r59136 | andrew.kuchling | 2007-11-23 05:37:39 -0800 (Fri, 23 Nov 2007) | 1 line

  Add item
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  r59137 | skip.montanaro | 2007-11-23 09:08:35 -0800 (Fri, 23 Nov 2007) | 2 lines

  Make trace and doctest play nice together (issue 1429818).  Will backport.
........
  r59139 | skip.montanaro | 2007-11-23 09:12:47 -0800 (Fri, 23 Nov 2007) | 1 line

  issue 1429818
........
  r59144 | facundo.batista | 2007-11-23 09:59:00 -0800 (Fri, 23 Nov 2007) | 10 lines


  Major change in the internal structure of the Decimal
  number: now it does not store the mantissa as a tuple
  of numbers, but as a string.

  This avoids a lot of conversions, and achieves a
  speedup of 40%. The API remains intact.

  Thanks Mark Dickinson.
........
  r59146 | facundo.batista | 2007-11-23 10:14:50 -0800 (Fri, 23 Nov 2007) | 3 lines


  Test cases from Cowlishaw, v2.57. All are pased cleanly.
........
  r59156 | christian.heimes | 2007-11-23 17:36:02 -0800 (Fri, 23 Nov 2007) | 2 lines

  Added filename to compiling struct based on Martin's suggestion.
  I'm wonder why I was trying to add the filename to the node all the time. The compiling struct is more obvious.
........
  r59158 | christian.heimes | 2007-11-23 17:53:59 -0800 (Fri, 23 Nov 2007) | 2 lines

  Backport of fixes from py3k branch
  svn merge -r59131:HEAD ../../py3k/PCbuild9/ .
........
  r59159 | skip.montanaro | 2007-11-23 20:29:08 -0800 (Fri, 23 Nov 2007) | 1 line

  revert change that breaks test_doctest (which I forgot to run - sorry)
........
  r59162 | skip.montanaro | 2007-11-23 20:31:15 -0800 (Fri, 23 Nov 2007) | 1 line

  revert
........
  r59164 | georg.brandl | 2007-11-24 03:31:46 -0800 (Sat, 24 Nov 2007) | 3 lines

  #1344: document that you need to open std{in,out,err} with PIPE if you want
  communicate() to work as described.
........
  r59165 | georg.brandl | 2007-11-24 03:39:13 -0800 (Sat, 24 Nov 2007) | 2 lines

  #1467: fix documentation for TestResult.add{Error,Failure}.
........
  r59166 | georg.brandl | 2007-11-24 03:42:14 -0800 (Sat, 24 Nov 2007) | 2 lines

  #1355: remove mention of PyXML from xml.dom docs.
........
  r59169 | amaury.forgeotdarc | 2007-11-24 05:20:22 -0800 (Sat, 24 Nov 2007) | 2 lines

  Warning "<> not supported in 3.x" should be enabled only when the -3 option is set.
........
  r59170 | amaury.forgeotdarc | 2007-11-24 05:44:17 -0800 (Sat, 24 Nov 2007) | 3 lines

  Issue #1445: Fix a SystemError when accessing the ``cell_contents``
  attribute of an empty cell object.  Now a ValueError is raised.
........
  r59172 | georg.brandl | 2007-11-24 05:56:09 -0800 (Sat, 24 Nov 2007) | 3 lines

  #1735632: add O_NOATIME constant to os module.
  Also document a few other O_ constants that were missing from documentation.
........
  r59173 | skip.montanaro | 2007-11-24 06:30:47 -0800 (Sat, 24 Nov 2007) | 1 line

  back in these go - thanks to Titus Brown for the fix
........
  r59176 | martin.v.loewis | 2007-11-24 10:33:40 -0800 (Sat, 24 Nov 2007) | 2 lines

  Bug #1494: Document that appendChild removes first.
........
  r59186 | guido.van.rossum | 2007-11-26 14:16:49 -0800 (Mon, 26 Nov 2007) | 2 lines

  A thread-less variant of brownian.py, submitted by Michele Simoniato.
........

1 files changed, 219 insertions, 306 deletions

diff --git a/Lib/decimal.py b/Lib/decimal.py
index faf9bf7..7842cb2 100644
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -214,10 +214,10 @@ class InvalidOperation(DecimalException):
     def handle(self, context, *args):
         if args:
             if args[0] == 1:  # sNaN, must drop 's' but keep diagnostics
-                ans = Decimal((args[1]._sign, args[1]._int, 'n'))
+                ans = _dec_from_triple(args[1]._sign, args[1]._int, 'n', True)
                 return ans._fix_nan(context)
             elif args[0] == 2:
-                return Decimal( (args[1], args[2], 'n') )
+                return _dec_from_triple(args[1], args[2], 'n', True)
         return NaN
 
 
@@ -350,13 +350,13 @@ class Overflow(Inexact, Rounded):
         if sign == 0:
             if context.rounding == ROUND_CEILING:
                 return Infsign[sign]
-            return Decimal((sign, (9,)*context.prec,
-                            context.Emax-context.prec+1))
+            return _dec_from_triple(sign, '9'*context.prec,
+                            context.Emax-context.prec+1)
         if sign == 1:
             if context.rounding == ROUND_FLOOR:
                 return Infsign[sign]
-            return Decimal( (sign, (9,)*context.prec,
-                             context.Emax-context.prec+1))
+            return _dec_from_triple(sign, '9'*context.prec,
+                             context.Emax-context.prec+1)
 
 
 class Underflow(Inexact, Rounded, Subnormal):
@@ -531,13 +531,21 @@ class Decimal(object):
         Decimal("314")
         """
 
+        # Note that the coefficient, self._int, is actually stored as
+        # a string rather than as a tuple of digits.  This speeds up
+        # the "digits to integer" and "integer to digits" conversions
+        # that are used in almost every arithmetic operation on
+        # Decimals.  This is an internal detail: the as_tuple function
+        # and the Decimal constructor still deal with tuples of
+        # digits.
+
         self = object.__new__(cls)
         self._is_special = False
 
         # From an internal working value
         if isinstance(value, _WorkRep):
             self._sign = value.sign
-            self._int = tuple(map(int, str(value.int)))
+            self._int = str(value.int)
             self._exp = int(value.exp)
             return self
 
@@ -556,7 +564,7 @@ class Decimal(object):
             else:
                 self._sign = 1
             self._exp = 0
-            self._int = tuple(map(int, str(abs(value))))
+            self._int = str(abs(value))
             return self
 
         # tuple/list conversion (possibly from as_tuple())
@@ -573,7 +581,7 @@ class Decimal(object):
             self._sign = value[0]
             if value[2] == 'F':
                 # infinity: value[1] is ignored
-                self._int = (0,)
+                self._int = '0'
                 self._exp = value[2]
                 self._is_special = True
             else:
@@ -590,12 +598,12 @@ class Decimal(object):
                                          "0 through 9.")
                 if value[2] in ('n', 'N'):
                     # NaN: digits form the diagnostic
-                    self._int = tuple(digits)
+                    self._int = ''.join(map(str, digits))
                     self._exp = value[2]
                     self._is_special = True
                 elif isinstance(value[2], int):
                     # finite number: digits give the coefficient
-                    self._int = tuple(digits or [0])
+                    self._int = ''.join(map(str, digits or [0]))
                     self._exp = value[2]
                     self._is_special = False
                 else:
@@ -608,38 +616,46 @@ class Decimal(object):
             raise TypeError("Cannot convert float to Decimal.  " +
                             "First convert the float to a string")
 
-        # Other argument types may require the context during interpretation
-        if context is None:
-            context = getcontext()
-
         # From a string
         # REs insist on real strings, so we can too.
         if isinstance(value, str):
-            if _isinfinity(value):
-                self._exp = 'F'
-                self._int = (0,)
-                self._is_special = True
-                if _isinfinity(value) == 1:
-                    self._sign = 0
+            m = _parser(value)
+            if m is None:
+                if context is None:
+                    context = getcontext()
+                return context._raise_error(ConversionSyntax,
+                                "Invalid literal for Decimal: %r" % value)
+
+            if m.group('sign') == "-":
+                self._sign = 1
+            else:
+                self._sign = 0
+            intpart = m.group('int')
+            if intpart is not None:
+                # finite number
+                fracpart = m.group('frac')
+                exp = int(m.group('exp') or '0')
+                if fracpart is not None:
+                    self._int = (intpart+fracpart).lstrip('0') or '0'
+                    self._exp = exp - len(fracpart)
                 else:
-                    self._sign = 1
-                return self
-            if _isnan(value):
-                sig, sign, diag = _isnan(value)
-                self._is_special = True
-                if sig == 1:
-                    self._exp = 'n'  # qNaN
-                else:  # sig == 2
-                    self._exp = 'N'  # sNaN
-                self._sign = sign
-                self._int = tuple(map(int, diag))  # Diagnostic info
-                return self
-            try:
-                self._sign, self._int, self._exp = _string2exact(value)
-            except ValueError:
+                    self._int = intpart.lstrip('0') or '0'
+                    self._exp = exp
+                self._is_special = False
+            else:
+                diag = m.group('diag')
+                if diag is not None:
+                    # NaN
+                    self._int = diag.lstrip('0')
+                    if m.group('signal'):
+                        self._exp = 'N'
+                    else:
+                        self._exp = 'n'
+                else:
+                    # infinity
+                    self._int = '0'
+                    self._exp = 'F'
                 self._is_special = True
-                return context._raise_error(ConversionSyntax,
-                                   "Invalid literal for Decimal: %r" % value)
             return self
 
         raise TypeError("Cannot convert %r to Decimal" % value)
@@ -709,7 +725,7 @@ class Decimal(object):
 
         NaNs and infinities are considered nonzero.
         """
-        return self._is_special or self._int[0] != 0
+        return self._is_special or self._int != '0'
 
     def __cmp__(self, other):
         other = _convert_other(other)
@@ -743,8 +759,8 @@ class Decimal(object):
         self_adjusted = self.adjusted()
         other_adjusted = other.adjusted()
         if self_adjusted == other_adjusted:
-            self_padded = self._int + (0,)*(self._exp - other._exp)
-            other_padded = other._int + (0,)*(other._exp - self._exp)
+            self_padded = self._int + '0'*(self._exp - other._exp)
+            other_padded = other._int + '0'*(other._exp - self._exp)
             return cmp(self_padded, other_padded) * (-1)**self._sign
         elif self_adjusted > other_adjusted:
             return (-1)**self._sign
@@ -827,7 +843,7 @@ class Decimal(object):
 
         To show the internals exactly as they are.
         """
-        return (self._sign, self._int, self._exp)
+        return (self._sign, tuple(map(int, self._int)), self._exp)
 
     def __repr__(self):
         """Represents the number as an instance of Decimal."""
@@ -843,10 +859,10 @@ class Decimal(object):
         if self._is_special:
             if self._isnan():
                 minus = '-'*self._sign
-                if self._int == (0,):
+                if self._int == '0':
                     info = ''
                 else:
-                    info = ''.join(map(str, self._int))
+                    info = self._int
                 if self._isnan() == 2:
                     return minus + 'sNaN' + info
                 return minus + 'NaN' + info
@@ -857,7 +873,7 @@ class Decimal(object):
         if context is None:
             context = getcontext()
 
-        tmp = list(map(str, self._int))
+        tmp = list(self._int)
         numdigits = len(self._int)
         leftdigits = self._exp + numdigits
         if eng and not self:  # self = 0eX wants 0[.0[0]]eY, not [[0]0]0eY
@@ -1030,7 +1046,7 @@ class Decimal(object):
             sign = min(self._sign, other._sign)
             if negativezero:
                 sign = 1
-            ans = Decimal( (sign, (0,), exp))
+            ans = _dec_from_triple(sign, '0', exp)
             if shouldround:
                 ans = ans._fix(context)
             return ans
@@ -1055,7 +1071,7 @@ class Decimal(object):
         if op1.sign != op2.sign:
             # Equal and opposite
             if op1.int == op2.int:
-                ans = Decimal((negativezero, (0,), exp))
+                ans = _dec_from_triple(negativezero, '0', exp)
                 if shouldround:
                     ans = ans._fix(context)
                 return ans
@@ -1121,7 +1137,7 @@ class Decimal(object):
         For example:
         Decimal('5.624e10')._increment() == Decimal('5.625e10')
         """
-        L = list(self._int)
+        L = list(map(int, self._int))
         L[-1] += 1
         spot = len(L)-1
         while L[spot] == 10:
@@ -1131,7 +1147,7 @@ class Decimal(object):
                 break
             L[spot-1] += 1
             spot -= 1
-        return Decimal((self._sign, L, self._exp))
+        return _dec_from_triple(self._sign, "".join(map(str, L)), self._exp)
 
     def __mul__(self, other, context=None):
         """Return self * other.
@@ -1167,20 +1183,20 @@ class Decimal(object):
 
         # Special case for multiplying by zero
         if not self or not other:
-            ans = Decimal((resultsign, (0,), resultexp))
+            ans = _dec_from_triple(resultsign, '0', resultexp)
             if shouldround:
                 # Fixing in case the exponent is out of bounds
                 ans = ans._fix(context)
             return ans
 
         # Special case for multiplying by power of 10
-        if self._int == (1,):
-            ans = Decimal((resultsign, other._int, resultexp))
+        if self._int == '1':
+            ans = _dec_from_triple(resultsign, other._int, resultexp)
             if shouldround:
                 ans = ans._fix(context)
             return ans
-        if other._int == (1,):
-            ans = Decimal((resultsign, self._int, resultexp))
+        if other._int == '1':
+            ans = _dec_from_triple(resultsign, self._int, resultexp)
             if shouldround:
                 ans = ans._fix(context)
             return ans
@@ -1188,9 +1204,7 @@ class Decimal(object):
         op1 = _WorkRep(self)
         op2 = _WorkRep(other)
 
-        ans = Decimal((resultsign,
-                       tuple(map(int, str(op1.int * op2.int))),
-                       resultexp))
+        ans = _dec_from_triple(resultsign, str(op1.int * op2.int), resultexp)
         if shouldround:
             ans = ans._fix(context)
 
@@ -1221,7 +1235,7 @@ class Decimal(object):
 
             if other._isinfinity():
                 context._raise_error(Clamped, 'Division by infinity')
-                return Decimal((sign, (0,), context.Etiny()))
+                return _dec_from_triple(sign, '0', context.Etiny())
 
         # Special cases for zeroes
         if not other:
@@ -1253,7 +1267,7 @@ class Decimal(object):
                     coeff //= 10
                     exp += 1
 
-        ans = Decimal((sign, list(map(int, str(coeff))), exp))
+        ans = _dec_from_triple(sign, str(coeff), exp)
         return ans._fix(context)
 
     def _divide(self, other, context):
@@ -1270,7 +1284,7 @@ class Decimal(object):
 
         expdiff = self.adjusted() - other.adjusted()
         if not self or other._isinfinity() or expdiff <= -2:
-            return (Decimal((sign, (0,), 0)),
+            return (_dec_from_triple(sign, '0', 0),
                     self._rescale(ideal_exp, context.rounding))
         if expdiff <= context.prec:
             op1 = _WorkRep(self)
@@ -1281,9 +1295,8 @@ class Decimal(object):
                 op2.int *= 10**(op2.exp - op1.exp)
             q, r = divmod(op1.int, op2.int)
             if q < 10**context.prec:
-                return (Decimal((sign, list(map(int, str(q))), 0)),
-                        Decimal((self._sign, list(map(int, str(r))),
-                                ideal_exp)))
+                return (_dec_from_triple(sign, str(q), 0),
+                        _dec_from_triple(self._sign, str(r), ideal_exp))
 
         # Here the quotient is too large to be representable
         ans = context._raise_error(DivisionImpossible,
@@ -1411,7 +1424,7 @@ class Decimal(object):
         # self = 0 -> remainder = self, with ideal exponent
         ideal_exponent = min(self._exp, other._exp)
         if not self:
-            ans = Decimal((self._sign, (0,), ideal_exponent))
+            ans = _dec_from_triple(self._sign, '0', ideal_exponent)
             return ans._fix(context)
 
         # catch most cases of large or small quotient
@@ -1448,7 +1461,7 @@ class Decimal(object):
             sign = 1-sign
             r = -r
 
-        ans = Decimal((sign, list(map(int, str(r))), ideal_exponent))
+        ans = _dec_from_triple(sign, str(r), ideal_exponent)
         return ans._fix(context)
 
     def __floordiv__(self, other, context=None):
@@ -1500,9 +1513,9 @@ class Decimal(object):
                 raise OverflowError("Cannot convert infinity to int")
         s = (-1)**self._sign
         if self._exp >= 0:
-            return s*int(''.join(map(str, self._int)))*10**self._exp
+            return s*int(self._int)*10**self._exp
         else:
-            return s*int(''.join(map(str, self._int))[:self._exp] or '0')
+            return s*int(self._int[:self._exp] or '0')
 
     def _fix_nan(self, context):
         """Decapitate the payload of a NaN to fit the context"""
@@ -1512,11 +1525,8 @@ class Decimal(object):
         # 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))
+            payload = payload[len(payload)-max_payload_len:].lstrip('0')
+            return _dec_from_triple(self._sign, payload, self._exp, True)
         return Decimal(self)
 
     def _fix(self, context):
@@ -1549,7 +1559,7 @@ class Decimal(object):
             new_exp = min(max(self._exp, Etiny), exp_max)
             if new_exp != self._exp:
                 context._raise_error(Clamped)
-                return Decimal((self._sign, (0,), new_exp))
+                return _dec_from_triple(self._sign, '0', new_exp)
             else:
                 return Decimal(self)
 
@@ -1581,7 +1591,8 @@ class Decimal(object):
                     # we get here only if rescaling rounds the
                     # cofficient up to exactly 10**context.prec
                     if ans._exp < Etop:
-                        ans = Decimal((ans._sign, ans._int[:-1], ans._exp+1))
+                        ans = _dec_from_triple(ans._sign,
+                                                   ans._int[:-1], ans._exp+1)
                     else:
                         # Inexact and Rounded have already been raised
                         ans = context._raise_error(Overflow, 'above Emax',
@@ -1591,8 +1602,8 @@ class Decimal(object):
         # fold down if _clamp == 1 and self has too few digits
         if context._clamp == 1 and self._exp > Etop:
             context._raise_error(Clamped)
-            self_padded = self._int + (0,)*(self._exp - Etop)
-            return Decimal((self._sign, self_padded, Etop))
+            self_padded = self._int + '0'*(self._exp - Etop)
+            return _dec_from_triple(self._sign, self_padded, Etop)
 
         # here self was representable to begin with; return unchanged
         return Decimal(self)
@@ -1607,29 +1618,29 @@ class Decimal(object):
     def _round_down(self, prec):
         """Also known as round-towards-0, truncate."""
         newexp = self._exp + len(self._int) - prec
-        return Decimal((self._sign, self._int[:prec] or (0,), newexp))
+        return _dec_from_triple(self._sign, self._int[:prec] or '0', newexp)
 
     def _round_up(self, prec):
         """Rounds away from 0."""
         newexp = self._exp + len(self._int) - prec
-        tmp = Decimal((self._sign, self._int[:prec] or (0,), newexp))
+        tmp = _dec_from_triple(self._sign, self._int[:prec] or '0', newexp)
         for digit in self._int[prec:]:
-            if digit != 0:
+            if digit != '0':
                 return tmp._increment()
         return tmp
 
     def _round_half_up(self, prec):
         """Rounds 5 up (away from 0)"""
-        if self._int[prec] >= 5:
+        if self._int[prec] in '56789':
             return self._round_up(prec)
         else:
             return self._round_down(prec)
 
     def _round_half_down(self, prec):
         """Round 5 down"""
-        if self._int[prec] == 5:
+        if self._int[prec] == '5':
             for digit in self._int[prec+1:]:
-                if digit != 0:
+                if digit != '0':
                     break
             else:
                 return self._round_down(prec)
@@ -1637,7 +1648,7 @@ class Decimal(object):
 
     def _round_half_even(self, prec):
         """Round 5 to even, rest to nearest."""
-        if prec and self._int[prec-1] & 1:
+        if prec and self._int[prec-1] in '13579':
             return self._round_half_up(prec)
         else:
             return self._round_half_down(prec)
@@ -1658,7 +1669,7 @@ class Decimal(object):
 
     def _round_05up(self, prec):
         """Round down unless digit prec-1 is 0 or 5."""
-        if prec == 0 or self._int[prec-1] in (0, 5):
+        if prec == 0 or self._int[prec-1] in '05':
             return self._round_up(prec)
         else:
             return self._round_down(prec)
@@ -1776,7 +1787,7 @@ class Decimal(object):
             base = pow(base, 10, modulo)
         base = pow(base, exponent.int, modulo)
 
-        return Decimal((sign, list(map(int, str(base))), 0))
+        return _dec_from_triple(sign, str(base), 0)
 
     def _power_exact(self, other, p):
         """Attempt to compute self**other exactly.
@@ -1866,7 +1877,7 @@ class Decimal(object):
                 zeros = min(exponent-ideal_exponent, p-1)
             else:
                 zeros = 0
-            return Decimal((0, (1,) + (0,)*zeros, exponent-zeros))
+            return _dec_from_triple(0, '1' + '0'*zeros, exponent-zeros)
 
         # case where y is negative: xc must be either a power
         # of 2 or a power of 5.
@@ -1927,7 +1938,7 @@ class Decimal(object):
             if xc >= 10**p:
                 return None
             xe = -e-xe
-            return Decimal((0, list(map(int, str(xc))), xe))
+            return _dec_from_triple(0, str(xc), xe)
 
         # now y is positive; find m and n such that y = m/n
         if ye >= 0:
@@ -1989,7 +2000,7 @@ class Decimal(object):
             zeros = min(xe-ideal_exponent, p-len(str_xc))
         else:
             zeros = 0
-        return Decimal((0, list(map(int, str_xc))+[0,]*zeros, xe-zeros))
+        return _dec_from_triple(0, str_xc+'0'*zeros, xe-zeros)
 
     def __pow__(self, other, modulo=None, context=None):
         """Return self ** other [ % modulo].
@@ -2050,12 +2061,12 @@ class Decimal(object):
                     return context._raise_error(InvalidOperation,
                         'x ** y with x negative and y not an integer')
             # negate self, without doing any unwanted rounding
-            self = Decimal((0, self._int, self._exp))
+            self = self.copy_negate()
 
         # 0**(+ve or Inf)= 0; 0**(-ve or -Inf) = Infinity
         if not self:
             if other._sign == 0:
-                return Decimal((result_sign, (0,), 0))
+                return _dec_from_triple(result_sign, '0', 0)
             else:
                 return Infsign[result_sign]
 
@@ -2064,7 +2075,7 @@ class Decimal(object):
             if other._sign == 0:
                 return Infsign[result_sign]
             else:
-                return Decimal((result_sign, (0,), 0))
+                return _dec_from_triple(result_sign, '0', 0)
 
         # 1**other = 1, but the choice of exponent and the flags
         # depend on the exponent of self, and on whether other is a
@@ -2091,7 +2102,7 @@ class Decimal(object):
                 context._raise_error(Rounded)
                 exp = 1-context.prec
 
-            return Decimal((result_sign, (1,)+(0,)*-exp, exp))
+            return _dec_from_triple(result_sign, '1'+'0'*-exp, exp)
 
         # compute adjusted exponent of self
         self_adj = self.adjusted()
@@ -2100,7 +2111,7 @@ class Decimal(object):
         # self ** -infinity is infinity if self < 1, 0 if self > 1
         if other._isinfinity():
             if (other._sign == 0) == (self_adj < 0):
-                return Decimal((result_sign, (0,), 0))
+                return _dec_from_triple(result_sign, '0', 0)
             else:
                 return Infsign[result_sign]
 
@@ -2118,19 +2129,19 @@ class Decimal(object):
             # self > 1 and other +ve, or self < 1 and other -ve
             # possibility of overflow
             if bound >= len(str(context.Emax)):
-                ans = Decimal((result_sign, (1,), context.Emax+1))
+                ans = _dec_from_triple(result_sign, '1', context.Emax+1)
         else:
             # self > 1 and other -ve, or self < 1 and other +ve
             # possibility of underflow to 0
             Etiny = context.Etiny()
             if bound >= len(str(-Etiny)):
-                ans = Decimal((result_sign, (1,), Etiny-1))
+                ans = _dec_from_triple(result_sign, '1', Etiny-1)
 
         # try for an exact result with precision +1
         if ans is None:
             ans = self._power_exact(other, context.prec + 1)
             if ans is not None and result_sign == 1:
-                ans = Decimal((1, ans._int, ans._exp))
+                ans = _dec_from_triple(1, ans._int, ans._exp)
 
         # usual case: inexact result, x**y computed directly as exp(y*log(x))
         if ans is None:
@@ -2151,7 +2162,7 @@ class Decimal(object):
                     break
                 extra += 3
 
-            ans = Decimal((result_sign, list(map(int, str(coeff))), exp))
+            ans = _dec_from_triple(result_sign, str(coeff), exp)
 
         # the specification says that for non-integer other we need to
         # raise Inexact, even when the result is actually exact.  In
@@ -2163,7 +2174,8 @@ class Decimal(object):
             # pad with zeros up to length context.prec+1 if necessary
             if len(ans._int) <= context.prec:
                 expdiff = context.prec+1 - len(ans._int)
-                ans = Decimal((ans._sign, ans._int+(0,)*expdiff, ans._exp-expdiff))
+                ans = _dec_from_triple(ans._sign, ans._int+'0'*expdiff,
+                                       ans._exp-expdiff)
             if ans.adjusted() < context.Emin:
                 context._raise_error(Underflow)
 
@@ -2195,14 +2207,14 @@ class Decimal(object):
             return dup
 
         if not dup:
-            return Decimal( (dup._sign, (0,), 0) )
+            return _dec_from_triple(dup._sign, '0', 0)
         exp_max = [context.Emax, context.Etop()][context._clamp]
         end = len(dup._int)
         exp = dup._exp
-        while dup._int[end-1] == 0 and exp < exp_max:
+        while dup._int[end-1] == '0' and exp < exp_max:
             exp += 1
             end -= 1
-        return Decimal( (dup._sign, dup._int[:end], exp) )
+        return _dec_from_triple(dup._sign, dup._int[:end], exp)
 
     def quantize(self, exp, rounding=None, context=None, watchexp=True):
         """Quantize self so its exponent is the same as that of exp.
@@ -2243,7 +2255,7 @@ class Decimal(object):
                    'target exponent out of bounds in quantize')
 
         if not self:
-            ans = Decimal((self._sign, (0,), exp._exp))
+            ans = _dec_from_triple(self._sign, '0', exp._exp)
             return ans._fix(context)
 
         self_adjusted = self.adjusted()
@@ -2303,17 +2315,18 @@ class Decimal(object):
         if self._is_special:
             return Decimal(self)
         if not self:
-            return Decimal((self._sign, (0,), exp))
+            return _dec_from_triple(self._sign, '0', exp)
 
         if self._exp >= exp:
             # pad answer with zeros if necessary
-            return Decimal((self._sign, self._int + (0,)*(self._exp - exp), exp))
+            return _dec_from_triple(self._sign,
+                                        self._int + '0'*(self._exp - exp), exp)
 
         # too many digits; round and lose data.  If self.adjusted() <
         # exp-1, replace self by 10**(exp-1) before rounding
         digits = len(self._int) + self._exp - exp
         if digits < 0:
-            self = Decimal((self._sign, (1,), exp-1))
+            self = _dec_from_triple(self._sign, '1', exp-1)
             digits = 0
         this_function = getattr(self, self._pick_rounding_function[rounding])
         return this_function(digits)
@@ -2336,7 +2349,7 @@ class Decimal(object):
         if self._exp >= 0:
             return Decimal(self)
         if not self:
-            return Decimal((self._sign, (0,), 0))
+            return _dec_from_triple(self._sign, '0', 0)
         if context is None:
             context = getcontext()
         if rounding is None:
@@ -2378,7 +2391,7 @@ class Decimal(object):
 
         if not self:
             # exponent = self._exp // 2.  sqrt(-0) = -0
-            ans = Decimal((self._sign, (0,), self._exp // 2))
+            ans = _dec_from_triple(self._sign, '0', self._exp // 2)
             return ans._fix(context)
 
         if context is None:
@@ -2455,7 +2468,7 @@ class Decimal(object):
             if n % 5 == 0:
                 n += 1
 
-        ans = Decimal((0, list(map(int, str(n))), e))
+        ans = _dec_from_triple(0, str(n), e)
 
         # round, and fit to current context
         context = context._shallow_copy()
@@ -2552,13 +2565,13 @@ class Decimal(object):
         if self._exp >= 0:
             return True
         rest = self._int[self._exp:]
-        return rest == (0,)*len(rest)
+        return rest == '0'*len(rest)
 
     def _iseven(self):
         """Returns True if self is even.  Assumes self is an integer."""
         if not self or self._exp > 0:
             return True
-        return self._int[-1+self._exp] & 1 == 0
+        return self._int[-1+self._exp] in '02468'
 
     def adjusted(self):
         """Return the adjusted exponent of self"""
@@ -2680,18 +2693,19 @@ class Decimal(object):
 
     def copy_abs(self):
         """Returns a copy with the sign set to 0. """
-        return Decimal((0, self._int, self._exp))
+        return _dec_from_triple(0, self._int, self._exp, self._is_special)
 
     def copy_negate(self):
         """Returns a copy with the sign inverted."""
         if self._sign:
-            return Decimal((0, self._int, self._exp))
+            return _dec_from_triple(0, self._int, self._exp, self._is_special)
         else:
-            return Decimal((1, self._int, self._exp))
+            return _dec_from_triple(1, self._int, self._exp, self._is_special)
 
     def copy_sign(self, other):
         """Returns self with the sign of other."""
-        return Decimal((other._sign, self._int, self._exp))
+        return _dec_from_triple(other._sign, self._int,
+                                self._exp, self._is_special)
 
     def exp(self, context=None):
         """Returns e ** self."""
@@ -2730,16 +2744,16 @@ class Decimal(object):
         # larger exponent the result either overflows or underflows.
         if self._sign == 0 and adj > len(str((context.Emax+1)*3)):
             # overflow
-            ans = Decimal((0, (1,), context.Emax+1))
+            ans = _dec_from_triple(0, '1', context.Emax+1)
         elif self._sign == 1 and adj > len(str((-context.Etiny()+1)*3)):
             # underflow to 0
-            ans = Decimal((0, (1,), context.Etiny()-1))
+            ans = _dec_from_triple(0, '1', context.Etiny()-1)
         elif self._sign == 0 and adj < -p:
             # p+1 digits; final round will raise correct flags
-            ans = Decimal((0, (1,) + (0,)*(p-1) + (1,), -p))
+            ans = _dec_from_triple(0, '1' + '0'*(p-1) + '1', -p)
         elif self._sign == 1 and adj < -p-1:
             # p+1 digits; final round will raise correct flags
-            ans = Decimal((0, (9,)*(p+1), -p-1))
+            ans = _dec_from_triple(0, '9'*(p+1), -p-1)
         # general case
         else:
             op = _WorkRep(self)
@@ -2757,7 +2771,7 @@ class Decimal(object):
                     break
                 extra += 3
 
-            ans = Decimal((0, list(map(int, str(coeff))), exp))
+            ans = _dec_from_triple(0, str(coeff), exp)
 
         # at this stage, ans should round correctly with *any*
         # rounding mode, not just with ROUND_HALF_EVEN
@@ -2822,7 +2836,7 @@ class Decimal(object):
 
     def is_zero(self):
         """Return True if self is a zero; otherwise return False."""
-        return not self._is_special and self._int[0] == 0
+        return not self._is_special and self._int == '0'
 
     def _ln_exp_bound(self):
         """Compute a lower bound for the adjusted exponent of self.ln().
@@ -2891,7 +2905,7 @@ class Decimal(object):
             if coeff % (5*10**(len(str(abs(coeff)))-p-1)):
                 break
             places += 3
-        ans = Decimal((int(coeff<0), list(map(int, str(abs(coeff)))), -places))
+        ans = _dec_from_triple(int(coeff<0), str(abs(coeff)), -places)
 
         context = context._shallow_copy()
         rounding = context._set_rounding(ROUND_HALF_EVEN)
@@ -2954,7 +2968,7 @@ class Decimal(object):
                                         'log10 of a negative value')
 
         # log10(10**n) = n
-        if self._int[0] == 1 and self._int[1:] == (0,)*(len(self._int) - 1):
+        if self._int[0] == '1' and self._int[1:] == '0'*(len(self._int) - 1):
             # answer may need rounding
             ans = Decimal(self._exp + len(self._int) - 1)
         else:
@@ -2972,8 +2986,7 @@ class Decimal(object):
                 if coeff % (5*10**(len(str(abs(coeff)))-p-1)):
                     break
                 places += 3
-            ans = Decimal((int(coeff<0), list(map(int, str(abs(coeff)))),
-                          -places))
+            ans = _dec_from_triple(int(coeff<0), str(abs(coeff)), -places)
 
         context = context._shallow_copy()
         rounding = context._set_rounding(ROUND_HALF_EVEN)
@@ -3020,19 +3033,19 @@ class Decimal(object):
         if self._sign != 0 or self._exp != 0:
             return False
         for dig in self._int:
-            if dig not in (0, 1):
+            if dig not in '01':
                 return False
         return True
 
     def _fill_logical(self, context, opa, opb):
         dif = context.prec - len(opa)
         if dif > 0:
-            opa = (0,)*dif + opa
+            opa = '0'*dif + opa
         elif dif < 0:
             opa = opa[-context.prec:]
         dif = context.prec - len(opb)
         if dif > 0:
-            opb = (0,)*dif + opb
+            opb = '0'*dif + opb
         elif dif < 0:
             opb = opb[-context.prec:]
         return opa, opb
@@ -3048,22 +3061,15 @@ class Decimal(object):
         (opa, opb) = self._fill_logical(context, self._int, other._int)
 
         # make the operation, and clean starting zeroes
-        result = [a&b for a,b in zip(opa,opb)]
-        for i,d in enumerate(result):
-            if d == 1:
-                break
-        result = tuple(result[i:])
-
-        # if empty, we must have at least a zero
-        if not result:
-            result = (0,)
-        return Decimal((0, result, 0))
+        result = "".join([str(int(a)&int(b)) for a,b in zip(opa,opb)])
+        return _dec_from_triple(0, result.lstrip('0') or '0', 0)
 
     def logical_invert(self, context=None):
         """Invert all its digits."""
         if context is None:
             context = getcontext()
-        return self.logical_xor(Decimal((0,(1,)*context.prec,0)), context)
+        return self.logical_xor(_dec_from_triple(0,'1'*context.prec,0),
+                                context)
 
     def logical_or(self, other, context=None):
         """Applies an 'or' operation between self and other's digits."""
@@ -3076,16 +3082,8 @@ class Decimal(object):
         (opa, opb) = self._fill_logical(context, self._int, other._int)
 
         # make the operation, and clean starting zeroes
-        result = [a|b for a,b in zip(opa,opb)]
-        for i,d in enumerate(result):
-            if d == 1:
-                break
-        result = tuple(result[i:])
-
-        # if empty, we must have at least a zero
-        if not result:
-            result = (0,)
-        return Decimal((0, result, 0))
+        result = "".join(str(int(a)|int(b)) for a,b in zip(opa,opb))
+        return _dec_from_triple(0, result.lstrip('0') or '0', 0)
 
     def logical_xor(self, other, context=None):
         """Applies an 'xor' operation between self and other's digits."""
@@ -3098,16 +3096,8 @@ class Decimal(object):
         (opa, opb) = self._fill_logical(context, self._int, other._int)
 
         # make the operation, and clean starting zeroes
-        result = [a^b for a,b in zip(opa,opb)]
-        for i,d in enumerate(result):
-            if d == 1:
-                break
-        result = tuple(result[i:])
-
-        # if empty, we must have at least a zero
-        if not result:
-            result = (0,)
-        return Decimal((0, result, 0))
+        result = "".join(str(int(a)^int(b)) for a,b in zip(opa,opb))
+        return _dec_from_triple(0, result.lstrip('0') or '0', 0)
 
     def max_mag(self, other, context=None):
         """Compares the values numerically with their sign ignored."""
@@ -3185,7 +3175,7 @@ class Decimal(object):
         if self._isinfinity() == -1:
             return negInf
         if self._isinfinity() == 1:
-            return Decimal((0, (9,)*context.prec, context.Etop()))
+            return _dec_from_triple(0, '9'*context.prec, context.Etop())
 
         context = context.copy()
         context._set_rounding(ROUND_FLOOR)
@@ -3193,7 +3183,8 @@ class Decimal(object):
         new_self = self._fix(context)
         if new_self != self:
             return new_self
-        return self.__sub__(Decimal((0, (1,), context.Etiny()-1)), context)
+        return self.__sub__(_dec_from_triple(0, '1', context.Etiny()-1),
+                            context)
 
     def next_plus(self, context=None):
         """Returns the smallest representable number larger than itself."""
@@ -3207,7 +3198,7 @@ class Decimal(object):
         if self._isinfinity() == 1:
             return Inf
         if self._isinfinity() == -1:
-            return Decimal((1, (9,)*context.prec, context.Etop()))
+            return _dec_from_triple(1, '9'*context.prec, context.Etop())
 
         context = context.copy()
         context._set_rounding(ROUND_CEILING)
@@ -3215,7 +3206,8 @@ class Decimal(object):
         new_self = self._fix(context)
         if new_self != self:
             return new_self
-        return self.__add__(Decimal((0, (1,), context.Etiny()-1)), context)
+        return self.__add__(_dec_from_triple(0, '1', context.Etiny()-1),
+                            context)
 
     def next_toward(self, other, context=None):
         """Returns the number closest to self, in the direction towards other.
@@ -3237,7 +3229,7 @@ class Decimal(object):
 
         comparison = self.__cmp__(other)
         if comparison == 0:
-            return Decimal((other._sign, self._int, self._exp))
+            return self.copy_sign(other)
 
         if comparison == -1:
             ans = self.next_plus(context)
@@ -3331,19 +3323,12 @@ class Decimal(object):
         rotdig = self._int
         topad = context.prec - len(rotdig)
         if topad:
-            rotdig = ((0,)*topad) + rotdig
+            rotdig = '0'*topad + rotdig
 
         # let's rotate!
         rotated = rotdig[torot:] + rotdig[:torot]
-
-        # clean starting zeroes
-        for i,d in enumerate(rotated):
-            if d != 0:
-                break
-        rotated = rotated[i:]
-
-        return Decimal((self._sign, rotated, self._exp))
-
+        return _dec_from_triple(self._sign,
+                                rotated.lstrip('0') or '0', self._exp)
 
     def scaleb (self, other, context=None):
         """Returns self operand after adding the second value to its exp."""
@@ -3364,7 +3349,7 @@ class Decimal(object):
         if self._isinfinity():
             return Decimal(self)
 
-        d = Decimal((self._sign, self._int, self._exp + int(other)))
+        d = _dec_from_triple(self._sign, self._int, self._exp + int(other))
         d = d._fix(context)
         return d
 
@@ -3392,26 +3377,17 @@ class Decimal(object):
         rotdig = self._int
         topad = context.prec - len(rotdig)
         if topad:
-            rotdig = ((0,)*topad) + rotdig
+            rotdig = '0'*topad + rotdig
 
         # let's shift!
         if torot < 0:
             rotated = rotdig[:torot]
         else:
-            rotated = (rotdig + ((0,) * torot))
+            rotated = rotdig + '0'*torot
             rotated = rotated[-context.prec:]
 
-        # clean starting zeroes
-        if rotated:
-            for i,d in enumerate(rotated):
-                if d != 0:
-                    break
-            rotated = rotated[i:]
-        else:
-            rotated = (0,)
-
-        return Decimal((self._sign, rotated, self._exp))
-
+        return _dec_from_triple(self._sign,
+                                    rotated.lstrip('0') or '0', self._exp)
 
     # Support for pickling, copy, and deepcopy
     def __reduce__(self):
@@ -3427,6 +3403,22 @@ class Decimal(object):
             return self     # My components are also immutable
         return self.__class__(str(self))
 
+def _dec_from_triple(sign, coefficient, exponent, special=False):
+    """Create a decimal instance directly, without any validation,
+    normalization (e.g. removal of leading zeros) or argument
+    conversion.
+
+    This function is for *internal use only*.
+    """
+
+    self = object.__new__(Decimal)
+    self._sign = sign
+    self._int = coefficient
+    self._exp = exponent
+    self._is_special = special
+
+    return self
+
 ##### Context class #######################################################
 
 
@@ -4775,10 +4767,7 @@ class _WorkRep(object):
             self.exp = None
         elif isinstance(value, Decimal):
             self.sign = value._sign
-            cum = 0
-            for digit  in value._int:
-                cum = cum * 10 + digit
-            self.int = cum
+            self.int = int(value._int)
             self.exp = value._exp
         else:
             # assert isinstance(value, tuple)
@@ -5175,53 +5164,6 @@ def _convert_other(other, raiseit=False):
         raise TypeError("Unable to convert %s to Decimal" % other)
     return NotImplemented
 
-_infinity_map = {
-    'inf' : 1,
-    'infinity' : 1,
-    '+inf' : 1,
-    '+infinity' : 1,
-    '-inf' : -1,
-    '-infinity' : -1
-}
-
-def _isinfinity(num):
-    """Determines whether a string or float is infinity.
-
-    +1 for negative infinity; 0 for finite ; +1 for positive infinity
-    """
-    num = str(num).lower()
-    return _infinity_map.get(num, 0)
-
-def _isnan(num):
-    """Determines whether a string or float is NaN
-
-    (1, sign, diagnostic info as string) => NaN
-    (2, sign, diagnostic info as string) => sNaN
-    0 => not a NaN
-    """
-    num = str(num).lower()
-    if not num:
-        return 0
-
-    # Get the sign, get rid of trailing [+-]
-    sign = 0
-    if num[0] == '+':
-        num = num[1:]
-    elif num[0] == '-':  # elif avoids '+-nan'
-        num = num[1:]
-        sign = 1
-
-    if num.startswith('nan'):
-        if len(num) > 3 and not num[3:].isdigit():  # diagnostic info
-            return 0
-        return (1, sign, num[3:].lstrip('0'))
-    if num.startswith('snan'):
-        if len(num) > 4 and not num[4:].isdigit():
-            return 0
-        return (2, sign, num[4:].lstrip('0'))
-    return 0
-
-
 ##### Setup Specific Contexts ############################################
 
 # The default context prototype used by Context()
@@ -5255,91 +5197,62 @@ ExtendedContext = Context(
 )
 
 
-##### Useful Constants (internal use only) ################################
-
-# Reusable defaults
-Inf = Decimal('Inf')
-negInf = Decimal('-Inf')
-NaN = Decimal('NaN')
-Dec_0 = Decimal(0)
-Dec_p1 = Decimal(1)
-Dec_n1 = Decimal(-1)
-Dec_p2 = Decimal(2)
-Dec_n2 = Decimal(-2)
-
-# Infsign[sign] is infinity w/ that sign
-Infsign = (Inf, negInf)
-
-
 ##### crud for parsing strings #############################################
 import re
 
-# There's an optional sign at the start, and an optional exponent
-# at the end.  The exponent has an optional sign and at least one
-# digit.  In between, must have either at least one digit followed
-# by an optional fraction, or a decimal point followed by at least
-# one digit.  Yuck.
+# Regular expression used for parsing numeric strings.  Additional
+# comments:
+#
+# 1. Uncomment the two '\s*' lines to allow leading and/or trailing
+# whitespace.  But note that the specification disallows whitespace in
+# a numeric string.
+#
+# 2. For finite numbers (not infinities and NaNs) the body of the
+# number between the optional sign and the optional exponent must have
+# at least one decimal digit, possibly after the decimal point.  The
+# lookahead expression '(?=\d|\.\d)' checks this.
+#
+# As the flag UNICODE is not enabled here, we're explicitly avoiding any
+# other meaning for \d than the numbers [0-9].
 
-_parser = re.compile(r"""
+import re
+_parser = re.compile(r"""     # A numeric string consists of:
 #    \s*
-    (?P<sign>[-+])?
+    (?P<sign>[-+])?           # an optional sign, followed by either...
     (
-        (?P<int>\d+) (\. (?P<frac>\d*))?
+        (?=\d|\.\d)           # ...a number (with at least one digit)
+        (?P<int>\d*)          # consisting of a (possibly empty) integer part
+        (\.(?P<frac>\d*))?    # followed by an optional fractional part
+        (E(?P<exp>[-+]?\d+))? # followed by an optional exponent, or...
     |
-        \. (?P<onlyfrac>\d+)
+        Inf(inity)?           # ...an infinity, or...
+    |
+        (?P<signal>s)?        # ...an (optionally signaling)
+        NaN                   # NaN
+        (?P<diag>\d*)         # with (possibly empty) diagnostic information.
     )
-    ([eE](?P<exp>[-+]? \d+))?
 #    \s*
     $
-""", re.VERBOSE).match  # Uncomment the \s* to allow leading or trailing spaces.
+""", re.VERBOSE | re.IGNORECASE).match
 
 del re
 
-def _string2exact(s):
-    """Return sign, n, p s.t.
 
-    Float string value == -1**sign * n * 10**p exactly
-    """
-    m = _parser(s)
-    if m is None:
-        raise ValueError("invalid literal for Decimal: %r" % s)
+##### Useful Constants (internal use only) ################################
 
-    if m.group('sign') == "-":
-        sign = 1
-    else:
-        sign = 0
+# Reusable defaults
+Inf = Decimal('Inf')
+negInf = Decimal('-Inf')
+NaN = Decimal('NaN')
+Dec_0 = Decimal(0)
+Dec_p1 = Decimal(1)
+Dec_n1 = Decimal(-1)
+Dec_p2 = Decimal(2)
+Dec_n2 = Decimal(-2)
 
-    exp = m.group('exp')
-    if exp is None:
-        exp = 0
-    else:
-        exp = int(exp)
+# Infsign[sign] is infinity w/ that sign
+Infsign = (Inf, negInf)
 
-    intpart = m.group('int')
-    if intpart is None:
-        intpart = ""
-        fracpart = m.group('onlyfrac')
-    else:
-        fracpart = m.group('frac')
-        if fracpart is None:
-            fracpart = ""
-
-    exp -= len(fracpart)
-
-    mantissa = intpart + fracpart
-    tmp = list(map(int, mantissa))
-    backup = tmp
-    while tmp and tmp[0] == 0:
-        del tmp[0]
-
-    # It's a zero
-    if not tmp:
-        if backup:
-            return (sign, tuple(backup), exp)
-        return (sign, (0,), exp)
-    mantissa = tuple(tmp)
-
-    return (sign, mantissa, exp)
 
 
 if __name__ == '__main__':