1 files changed, 56 insertions, 6 deletions
diff --git a/Lib/_pydecimal.py b/Lib/_pydecimal.py
index a5ea340e9d..0b40928ff8 100644
--- a/Lib/_pydecimal.py
+++ b/Lib/_pydecimal.py
@@ -148,7 +148,7 @@ __xname__ = __name__    # sys.modules lookup (--without-threads)
 __name__ = 'decimal'    # For pickling
 __version__ = '1.70'    # Highest version of the spec this complies with
                         # See http://speleotrove.com/decimal/
-__libmpdec_version__ = "2.4.1" # compatible libmpdec version
+__libmpdec_version__ = "2.4.2" # compatible libmpdec version
 
 import math as _math
 import numbers as _numbers
@@ -589,7 +589,7 @@ class Decimal(object):
         # From a string
         # REs insist on real strings, so we can too.
         if isinstance(value, str):
-            m = _parser(value.strip())
+            m = _parser(value.strip().replace("_", ""))
             if m is None:
                 if context is None:
                     context = getcontext()
@@ -1010,6 +1010,56 @@ class Decimal(object):
         """
         return DecimalTuple(self._sign, tuple(map(int, self._int)), self._exp)
 
+    def as_integer_ratio(self):
+        """Express a finite Decimal instance in the form n / d.
+
+        Returns a pair (n, d) of integers.  When called on an infinity
+        or NaN, raises OverflowError or ValueError respectively.
+
+        >>> Decimal('3.14').as_integer_ratio()
+        (157, 50)
+        >>> Decimal('-123e5').as_integer_ratio()
+        (-12300000, 1)
+        >>> Decimal('0.00').as_integer_ratio()
+        (0, 1)
+
+        """
+        if self._is_special:
+            if self.is_nan():
+                raise ValueError("cannot convert NaN to integer ratio")
+            else:
+                raise OverflowError("cannot convert Infinity to integer ratio")
+
+        if not self:
+            return 0, 1
+
+        # Find n, d in lowest terms such that abs(self) == n / d;
+        # we'll deal with the sign later.
+        n = int(self._int)
+        if self._exp >= 0:
+            # self is an integer.
+            n, d = n * 10**self._exp, 1
+        else:
+            # Find d2, d5 such that abs(self) = n / (2**d2 * 5**d5).
+            d5 = -self._exp
+            while d5 > 0 and n % 5 == 0:
+                n //= 5
+                d5 -= 1
+
+            # (n & -n).bit_length() - 1 counts trailing zeros in binary
+            # representation of n (provided n is nonzero).
+            d2 = -self._exp
+            shift2 = min((n & -n).bit_length() - 1, d2)
+            if shift2:
+                n >>= shift2
+                d2 -= shift2
+
+            d = 5**d5 << d2
+
+        if self._sign:
+            n = -n
+        return n, d
+
     def __repr__(self):
         """Represents the number as an instance of Decimal."""
         # Invariant:  eval(repr(d)) == d
@@ -4075,7 +4125,7 @@ class Context(object):
         This will make it round up for that operation.
         """
         rounding = self.rounding
-        self.rounding= type
+        self.rounding = type
         return rounding
 
     def create_decimal(self, num='0'):
@@ -4084,10 +4134,10 @@ class Context(object):
         This method implements the to-number operation of the
         IBM Decimal specification."""
 
-        if isinstance(num, str) and num != num.strip():
+        if isinstance(num, str) and (num != num.strip() or '_' in num):
             return self._raise_error(ConversionSyntax,
-                                     "no trailing or leading whitespace is "
-                                     "permitted.")
+                                     "trailing or leading whitespace and "
+                                     "underscores are not permitted.")
 
         d = Decimal(num, context=self)
         if d._isnan() and len(d._int) > self.prec - self.clamp: