Merged revisions 79583,79588-79589 via svnmerge from

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

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  r79583 | mark.dickinson | 2010-04-02 09:53:22 +0100 (Fri, 02 Apr 2010) | 7 lines

  Issue #2531: Make float-to-decimal comparisons return correct results.

  Float to decimal comparison operations now return a result based on
  the numeric values of the operands.  Decimal.__hash__ has also been
  fixed so that Decimal and float values that compare equal have equal
  hash value.
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  r79588 | mark.dickinson | 2010-04-02 11:17:07 +0100 (Fri, 02 Apr 2010) | 2 lines

  Issue #7279:  Make comparisons involving a Decimal sNaN signal InvalidOperation.
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  r79589 | mark.dickinson | 2010-04-02 11:35:12 +0100 (Fri, 02 Apr 2010) | 6 lines

  Issue #7279:  Make Decimal('nan') hashable.  Decimal('snan') remains unhashable.

  Also rewrite the Decimal __hash__ method so that it doesn't rely on
  float('inf') being valid: float('inf') could raise an exception on
  platforms not using IEEE 754 arithmetic.
........

Lib/test/test_decimal.py

@@ -26,6 +26,7 @@ with the corresponding argument.
 
 import math
 import os, sys
+import operator
 import pickle, copy
 import unittest
 from decimal import *
@@ -1096,18 +1097,56 @@ class DecimalArithmeticOperatorsTest(unittest.TestCase):
         self.assertEqual(abs(Decimal(45)), abs(Decimal(-45)))  # abs
 
     def test_nan_comparisons(self):
+        # comparisons involving signaling nans signal InvalidOperation
+
+        # order comparisons (<, <=, >, >=) involving only quiet nans
+        # also signal InvalidOperation
+
+        # equality comparisons (==, !=) involving only quiet nans
+        # don't signal, but return False or True respectively.
+
         n = Decimal('NaN')
         s = Decimal('sNaN')
         i = Decimal('Inf')
         f = Decimal('2')
-        for x, y in [(n, n), (n, i), (i, n), (n, f), (f, n),
-                     (s, n), (n, s), (s, i), (i, s), (s, f), (f, s), (s, s)]:
-            self.assertTrue(x != y)
-            self.assertTrue(not (x == y))
-            self.assertTrue(not (x < y))
-            self.assertTrue(not (x <= y))
-            self.assertTrue(not (x > y))
-            self.assertTrue(not (x >= y))
+
+        qnan_pairs = (n, n), (n, i), (i, n), (n, f), (f, n)
+        snan_pairs = (s, n), (n, s), (s, i), (i, s), (s, f), (f, s), (s, s)
+        order_ops = operator.lt, operator.le, operator.gt, operator.ge
+        equality_ops = operator.eq, operator.ne
+
+        # results when InvalidOperation is not trapped
+        for x, y in qnan_pairs + snan_pairs:
+            for op in order_ops + equality_ops:
+                got = op(x, y)
+                expected = True if op is operator.ne else False
+                self.assertIs(expected, got,
+                              "expected {0!r} for operator.{1}({2!r}, {3!r}); "
+                              "got {4!r}".format(
+                        expected, op.__name__, x, y, got))
+
+        # repeat the above, but this time trap the InvalidOperation
+        with localcontext() as ctx:
+            ctx.traps[InvalidOperation] = 1
+
+            for x, y in qnan_pairs:
+                for op in equality_ops:
+                    got = op(x, y)
+                    expected = True if op is operator.ne else False
+                    self.assertIs(expected, got,
+                                  "expected {0!r} for "
+                                  "operator.{1}({2!r}, {3!r}); "
+                                  "got {4!r}".format(
+                            expected, op.__name__, x, y, got))
+
+            for x, y in snan_pairs:
+                for op in equality_ops:
+                    self.assertRaises(InvalidOperation, operator.eq, x, y)
+                    self.assertRaises(InvalidOperation, operator.ne, x, y)
+
+            for x, y in qnan_pairs + snan_pairs:
+                for op in order_ops:
+                    self.assertRaises(InvalidOperation, op, x, y)
 
     def test_copy_sign(self):
         d = Decimal(1).copy_sign(Decimal(-2))
@@ -1213,6 +1252,23 @@ class DecimalUsabilityTest(unittest.TestCase):
         a.sort()
         self.assertEqual(a, b)
 
+    def test_decimal_float_comparison(self):
+        da = Decimal('0.25')
+        db = Decimal('3.0')
+        self.assert_(da < 3.0)
+        self.assert_(da <= 3.0)
+        self.assert_(db > 0.25)
+        self.assert_(db >= 0.25)
+        self.assert_(da != 1.5)
+        self.assert_(da == 0.25)
+        self.assert_(3.0 > da)
+        self.assert_(3.0 >= da)
+        self.assert_(0.25 < db)
+        self.assert_(0.25 <= db)
+        self.assert_(0.25 != db)
+        self.assert_(3.0 == db)
+        self.assert_(0.1 != Decimal('0.1'))
+
     def test_copy_and_deepcopy_methods(self):
         d = Decimal('43.24')
         c = copy.copy(d)
@@ -1223,6 +1279,10 @@ class DecimalUsabilityTest(unittest.TestCase):
     def test_hash_method(self):
         #just that it's hashable
         hash(Decimal(23))
+        hash(Decimal('Infinity'))
+        hash(Decimal('-Infinity'))
+        hash(Decimal('nan123'))
+        hash(Decimal('-NaN'))
 
         test_values = [Decimal(sign*(2**m + n))
                        for m in [0, 14, 15, 16, 17, 30, 31,
@@ -1257,10 +1317,19 @@ class DecimalUsabilityTest(unittest.TestCase):
 
         #the same hash that to an int
         self.assertEqual(hash(Decimal(23)), hash(23))
-        self.assertRaises(TypeError, hash, Decimal('NaN'))
+        self.assertRaises(TypeError, hash, Decimal('sNaN'))
         self.assertTrue(hash(Decimal('Inf')))
         self.assertTrue(hash(Decimal('-Inf')))
 
+        # check that the hashes of a Decimal float match when they
+        # represent exactly the same values
+        test_strings = ['inf', '-Inf', '0.0', '-.0e1',
+                        '34.0', '2.5', '112390.625', '-0.515625']
+        for s in test_strings:
+            f = float(s)
+            d = Decimal(s)
+            self.assertEqual(hash(f), hash(d))
+
         # check that the value of the hash doesn't depend on the
         # current context (issue #1757)
         c = getcontext()