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Author: Admin | 2025-04-28
Fold fold = (args == _time.localtime(stamp - dst_diff)) return datetime(*args, microsecond=dt.microsecond, tzinfo=self, fold=fold) def utcoffset(self, dt): if self._isdst(dt): return DSTOFFSET else: return STDOFFSET def dst(self, dt): if self._isdst(dt): return DSTDIFF else: return ZERO def tzname(self, dt): return _time.tzname[self._isdst(dt)] def _isdst(self, dt): tt = (dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second, dt.weekday(), 0, 0) stamp = _time.mktime(tt) tt = _time.localtime(stamp) return tt.tm_isdst > 0Local = LocalTimezone()# A complete implementation of current DST rules for major US time zones.def first_sunday_on_or_after(dt): days_to_go = 6 - dt.weekday() if days_to_go: dt += timedelta(days_to_go) return dt# US DST Rules## This is a simplified (i.e., wrong for a few cases) set of rules for US# DST start and end times. For a complete and up-to-date set of DST rules# and timezone definitions, visit the Olson Database (or try pytz):# http://www.twinsun.com/tz/tz-link.htm# https://sourceforge.net/projects/pytz/ (might not be up-to-date)## In the US, since 2007, DST starts at 2am (standard time) on the second# Sunday in March, which is the first Sunday on or after Mar 8.DSTSTART_2007 = datetime(1, 3, 8, 2)# and ends at 2am (DST time) on the first Sunday of Nov.DSTEND_2007 = datetime(1, 11, 1, 2)# From 1987 to 2006, DST used to start at 2am (standard time) on the first# Sunday in April and to end at 2am (DST time) on the last# Sunday of October, which is the first Sunday on or after Oct 25.DSTSTART_1987_2006 = datetime(1, 4, 1, 2)DSTEND_1987_2006 = datetime(1, 10, 25, 2)# From 1967 to 1986, DST used to start at 2am (standard time) on the last# Sunday in April (the one on or after April 24) and to end at 2am (DST time)# on the last Sunday of October, which is the first Sunday# on or after Oct 25.DSTSTART_1967_1986 = datetime(1, 4, 24, 2)DSTEND_1967_1986 = DSTEND_1987_2006def us_dst_range(year): # Find start and end times for US DST. For years before 1967, return # start = end for no DST. if 2006 year: dststart, dstend = DSTSTART_2007, DSTEND_2007 elif 1986 year 2007: dststart, dstend = DSTSTART_1987_2006, DSTEND_1987_2006 elif 1966 year 1987: dststart, dstend = DSTSTART_1967_1986, DSTEND_1967_1986 else: return (datetime(year, 1, 1), ) * 2 start = first_sunday_on_or_after(dststart.replace(year=year)) end = first_sunday_on_or_after(dstend.replace(year=year)) return start, endclass USTimeZone(tzinfo): def __init__(self, hours, reprname, stdname, dstname): self.stdoffset = timedelta(hours=hours) self.reprname = reprname self.stdname = stdname self.dstname = dstname def __repr__(self): return self.reprname def tzname(self, dt): if self.dst(dt): return self.dstname else: return self.stdname def utcoffset(self, dt): return self.stdoffset + self.dst(dt) def dst(self, dt): if dt is None or dt.tzinfo is None: # An exception may be sensible here, in one or both cases. # It depends on how you want to treat them. The default # fromutc() implementation (called by the default astimezone() # implementation) passes a datetime with dt.tzinfo is self. return
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