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