* initial commit (version 0.3.0)

1 files changed, 137 insertions, 0 deletions

diff --git a/src/isodate/tzinfo.py b/src/isodate/tzinfo.py
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+++ b/src/isodate/tzinfo.py
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+'''
+This module provides some datetime.tzinfo implementations. 
+
+All those classes are taken from the Python documentation.
+'''
+from datetime import timedelta, tzinfo
+import time
+
+ZERO = timedelta(0)
+# constant for zero time offset.
+
+class Utc(tzinfo):
+    '''UTC
+    
+    Universal time coordinated time zone.
+    '''
+    
+    def utcoffset(self, dt):
+        '''
+        Return offset from UTC in minutes east of UTC, which is ZERO for UTC.
+        '''
+        return ZERO
+
+    def tzname(self, dt):
+        '''
+        Return the time zone name corresponding to the datetime object dt, as a string.
+        '''
+        return "UTC"
+
+    def dst(self, dt):
+        '''
+        Return the daylight saving time (DST) adjustment, in minutes east of UTC.
+        '''
+        return ZERO
+
+UTC = Utc()
+# the default instance for UTC.
+
+class FixedOffset(tzinfo):
+    '''
+    A class building tzinfo objects for fixed-offset time zones.
+    
+    Note that FixedOffset(0, "UTC") is a different way to build a
+    UTC tzinfo object.
+    '''
+    
+    def __init__(self, offset_hours, offset_minutes, name):
+        '''
+        Initialise an instance with time offset and name.
+        The time offset should be positive for time zones east of UTC
+        and negate for time zones west of UTC. 
+        '''
+        self.__offset = timedelta(hours=offset_hours, minutes=offset_minutes)
+        self.__name = name
+
+    def utcoffset(self, dt):
+        '''
+        Return offset from UTC in minutes of UTC.
+        '''
+        return self.__offset
+
+    def tzname(self, dt):
+        '''
+        Return the time zone name corresponding to the datetime object dt, as a
+        string.
+        '''
+        return self.__name
+
+    def dst(self, dt):
+        '''
+        Return the daylight saving time (DST) adjustment, in minutes east of 
+        UTC.
+        '''
+        return ZERO
+    
+    def __repr__(self):
+        '''
+        Return nicely formatted repr string.
+        '''
+        return "<FixedOffset %r>" % self.__name
+
+
+STDOFFSET = timedelta(seconds = -time.timezone)
+# locale time zone offset
+
+# calculate local daylight saving offset if any.
+if time.daylight:
+    DSTOFFSET = timedelta(seconds = -time.altzone)
+else:
+    DSTOFFSET = STDOFFSET
+
+DSTDIFF = DSTOFFSET - STDOFFSET
+# difference between local time zone and local DST time zone
+
+class LocalTimezone(tzinfo):
+    '''
+    A class capturing the platform's idea of local time.
+    '''
+
+    def utcoffset(self, dt):
+        '''
+        Return offset from UTC in minutes of UTC.
+        '''
+        if self._isdst(dt):
+            return DSTOFFSET
+        else:
+            return STDOFFSET
+
+    def dst(self, dt):
+        '''
+        Return daylight saving offset.
+        '''
+        if self._isdst(dt):
+            return DSTDIFF
+        else:
+            return ZERO
+
+    def tzname(self, dt):
+        '''
+        Return the time zone name corresponding to the datetime object dt, as a
+        string.
+        '''
+        return time.tzname[self._isdst(dt)]
+
+    def _isdst(self, dt):
+        '''
+        Returns true if DST is active for given datetime object dt.
+        '''
+        tt = (dt.year, dt.month, dt.day,
+              dt.hour, dt.minute, dt.second,
+              dt.weekday(), 0, -1)
+        stamp = time.mktime(tt)
+        tt = time.localtime(stamp)
+        return tt.tm_isdst > 0
+
+LOCAL = LocalTimezone()
+# the default instance for local time zone.