* fixed precision problem with microseconds

2 files changed, 67 insertions, 51 deletions

diff --git a/src/isodate/isotime.py b/src/isodate/isotime.py
index c677f74..f0003d6 100644
--- a/src/isodate/isotime.py
+++ b/src/isodate/isotime.py
@@ -14,11 +14,11 @@
 #    may be used to endorse or promote products derived from this software
 #    without specific prior written permission.
 #
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 # ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
-# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
@@ -29,10 +29,10 @@ This modules provides a method to parse an ISO 8601:2004 time string to a
 Python datetime.time instance.
 
 It supports all basic and extended formats including time zone specifications
-as described in the ISO standard. 
+as described in the ISO standard.
 '''
 import re
-import math
+from decimal import Decimal
 from datetime import time
 
 from isodate.isostrf import strftime, TIME_EXT_COMPLETE, TZ_EXT
@@ -42,10 +42,11 @@ from isodate.isotzinfo import TZ_REGEX, build_tzinfo
 TIME_REGEX_CACHE = []
 # used to cache regular expressions to parse ISO time strings.
 
+
 def build_time_regexps():
     '''
     Build regular expressions to parse ISO time string.
-    
+
     The regular expressions are compiled and stored in TIME_REGEX_CACHE
     for later reuse.
     '''
@@ -91,10 +92,11 @@ def build_time_regexps():
                                            + TZ_REGEX))
     return TIME_REGEX_CACHE
 
+
 def parse_time(timestring):
     '''
     Parses ISO 8601 times into datetime.time objects.
-    
+
     Following ISO 8601 formats are supported:
       (as decimal separator a ',' or a '.' is allowed)
       hhmmss.ssTZD    basic complete time
@@ -117,34 +119,37 @@ def parse_time(timestring):
             for key, value in groups.items():
                 if value is not None:
                     groups[key] = value.replace(',', '.')
-            tzinfo = build_tzinfo(groups['tzname'], groups['tzsign'], 
-                                  int(groups['tzhour'] or 0), 
+            tzinfo = build_tzinfo(groups['tzname'], groups['tzsign'],
+                                  int(groups['tzhour'] or 0),
                                   int(groups['tzmin'] or 0))
             if 'second' in groups:
-                frac, second = math.modf(float(groups['second']))
-                microsecond = frac * 1e6
-                return time(int(groups['hour']), int(groups['minute']), 
-                            int(second), int(microsecond), tzinfo)
+                second = Decimal(groups['second'])
+                microsecond = (second - int(second)) * long(1e6)
+                # int(...) ... no rounding
+                # to_integral() ... rounding
+                return time(int(groups['hour']), int(groups['minute']),
+                            int(second), microsecond.to_integral(), tzinfo)
             if 'minute' in groups:
-                frac, minute = math.modf(float(groups['minute']))
-                frac, second = math.modf(frac * 60.0)
-                microsecond = frac * 1e6
-                return time(int(groups['hour']), int(minute), int(second), 
-                            int(microsecond), tzinfo)
+                minute = Decimal(groups['minute'])
+                second = (minute - int(minute)) * 60
+                microsecond = (second - int(second)) * long(1e6)
+                return time(int(groups['hour']), int(minute), int(second),
+                            microsecond.to_integral(), tzinfo)
             else:
                 microsecond, second, minute = 0, 0, 0
-            frac, hour = math.modf(float(groups['hour']))
-            frac, minute = math.modf(frac * 60.0)
-            frac, second = math.modf(frac * 60.0)
-            microsecond = frac * 1e6
-            return time(int(hour), int(minute), int(second), int(microsecond),
-                        tzinfo)
+            hour = Decimal(groups['hour'])
+            minute = (hour - int(hour)) * 60
+            second = (minute - int(minute)) * 60
+            microsecond = (second - int(second)) * long(1e6)
+            return time(int(hour), int(minute), int(second),
+                        microsecond.to_integral(), tzinfo)
     raise ISO8601Error('Unrecognised ISO 8601 time format: %r' % timestring)
 
+
 def time_isoformat(ttime, format=TIME_EXT_COMPLETE + TZ_EXT):
     '''
-    Format time strings. 
-    
+    Format time strings.
+
     This method is just a wrapper around isodate.isostrf.strftime and uses
     Time-Extended-Complete with extended time zone as default format.
     '''
diff --git a/src/tests/test_time.py b/src/tests/test_time.py
index 062995b..d71a3e2 100644
--- a/src/tests/test_time.py
+++ b/src/tests/test_time.py
@@ -14,11 +14,11 @@
 #    may be used to endorse or promote products derived from this software
 #    without specific prior written permission.
 #
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 # ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
-# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
@@ -46,51 +46,61 @@ TEST_CASES = [('232050', time(23, 20, 50), TIME_BAS_COMPLETE + TZ_BAS),
               ('23', time(23), TIME_HOUR),
               ('232050,5', time(23, 20, 50, 500000), None),
               ('23:20:50.5', time(23, 20, 50, 500000), None),
+              # test precision
+              ('15:33:42.123456', time(15, 33, 42, 123456), None),
+              ('15:33:42.1234564', time(15, 33, 42, 123456), None),
+              ('15:33:42.1234557', time(15, 33, 42, 123456), None),
               ('2320,8', time(23, 20, 48), None),
               ('23:20,8', time(23, 20, 48), None),
               ('23,3', time(23, 18), None),
-              ('232030Z', time(23, 20, 30, tzinfo=UTC), TIME_BAS_COMPLETE + TZ_BAS),
+              ('232030Z', time(23, 20, 30, tzinfo=UTC),
+                          TIME_BAS_COMPLETE + TZ_BAS),
               ('2320Z', time(23, 20, tzinfo=UTC), TIME_BAS_MINUTE + TZ_BAS),
               ('23Z', time(23, tzinfo=UTC), TIME_HOUR + TZ_BAS),
-              ('23:20:30Z', time(23, 20, 30, tzinfo=UTC), TIME_EXT_COMPLETE + TZ_EXT),
+              ('23:20:30Z', time(23, 20, 30, tzinfo=UTC),
+                            TIME_EXT_COMPLETE + TZ_EXT),
               ('23:20Z', time(23, 20, tzinfo=UTC), TIME_EXT_MINUTE + TZ_EXT),
-              ('152746+0100', time(15, 27, 46, tzinfo=FixedOffset(1, 0, '+0100')), TIME_BAS_COMPLETE + TZ_BAS),
-              ('152746-0500', time(15, 27, 46, tzinfo=FixedOffset(-5, 0, '-0500')), TIME_BAS_COMPLETE + TZ_BAS),
-              ('152746+01', time(15, 27, 46, 
+              ('152746+0100', time(15, 27, 46,
+                                   tzinfo=FixedOffset(1, 0, '+0100')),
+                              TIME_BAS_COMPLETE + TZ_BAS),
+              ('152746-0500', time(15, 27, 46,
+                                   tzinfo=FixedOffset(-5, 0, '-0500')),
+                              TIME_BAS_COMPLETE + TZ_BAS),
+              ('152746+01', time(15, 27, 46,
                                  tzinfo=FixedOffset(1, 0, '+01:00')),
-                                 TIME_BAS_COMPLETE + TZ_HOUR),
-              ('152746-05', time(15, 27, 46, 
+                            TIME_BAS_COMPLETE + TZ_HOUR),
+              ('152746-05', time(15, 27, 46,
                                  tzinfo=FixedOffset(-5, -0, '-05:00')),
-                                 TIME_BAS_COMPLETE + TZ_HOUR),
-              ('15:27:46+01:00', time(15, 27, 46, 
+                            TIME_BAS_COMPLETE + TZ_HOUR),
+              ('15:27:46+01:00', time(15, 27, 46,
                                       tzinfo=FixedOffset(1, 0, '+01:00')),
-                                      TIME_EXT_COMPLETE + TZ_EXT),
-              ('15:27:46-05:00', time(15, 27, 46, 
+                                 TIME_EXT_COMPLETE + TZ_EXT),
+              ('15:27:46-05:00', time(15, 27, 46,
                                       tzinfo=FixedOffset(-5, -0, '-05:00')),
-                                      TIME_EXT_COMPLETE + TZ_EXT),
-              ('15:27:46+01', time(15, 27, 46, 
+                                 TIME_EXT_COMPLETE + TZ_EXT),
+              ('15:27:46+01', time(15, 27, 46,
                                    tzinfo=FixedOffset(1, 0, '+01:00')),
-                                   TIME_EXT_COMPLETE + TZ_HOUR),
-              ('15:27:46-05', time(15, 27, 46, 
+                              TIME_EXT_COMPLETE + TZ_HOUR),
+              ('15:27:46-05', time(15, 27, 46,
                                    tzinfo=FixedOffset(-5, -0, '-05:00')),
-                                   TIME_EXT_COMPLETE + TZ_HOUR),
+                              TIME_EXT_COMPLETE + TZ_HOUR),
               ('1:17:30', None, TIME_EXT_COMPLETE)]
 
-    
+
 def create_testcase(timestring, expectation, format):
-    '''
+    """
     Create a TestCase class for a specific test.
-    
+
     This allows having a separate TestCase for each test tuple from the
     TEST_CASES list, so that a failed test won't stop other tests.
-    '''
-    
+    """
+
     class TestTime(unittest.TestCase):
         '''
         A test case template to parse an ISO time string into a time
         object.
         '''
-        
+
         def test_parse(self):
             '''
             Parse an ISO time string and compare it to the expected value.
@@ -100,7 +110,7 @@ def create_testcase(timestring, expectation, format):
             else:
                 result = parse_time(timestring)
                 self.assertEqual(result, expectation)
-                
+
         def test_format(self):
             '''
             Take time object and create ISO string from it.
@@ -112,9 +122,10 @@ def create_testcase(timestring, expectation, format):
             elif format is not None:
                 self.assertEqual(time_isoformat(expectation, format),
                                  timestring)
-            
+
     return unittest.TestLoader().loadTestsFromTestCase(TestTime)
 
+
 def test_suite():
     '''
     Construct a TestSuite instance for all test cases.