101 lines
3.2 KiB
Python
101 lines
3.2 KiB
Python
"Implementation of tzinfo classes for use with datetime.datetime."
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from __future__ import unicode_literals
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import time
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from datetime import timedelta, tzinfo
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from django.utils.encoding import force_str, force_text, DEFAULT_LOCALE_ENCODING
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# Python's doc say: "A tzinfo subclass must have an __init__() method that can
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# be called with no arguments". FixedOffset and LocalTimezone don't honor this
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# requirement. Defining __getinitargs__ is sufficient to fix copy/deepcopy as
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# well as pickling/unpickling.
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class FixedOffset(tzinfo):
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"Fixed offset in minutes east from UTC."
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def __init__(self, offset):
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if isinstance(offset, timedelta):
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self.__offset = offset
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offset = self.__offset.seconds // 60
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else:
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self.__offset = timedelta(minutes=offset)
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sign = '-' if offset < 0 else '+'
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self.__name = "%s%02d%02d" % (sign, abs(offset) / 60., abs(offset) % 60)
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def __repr__(self):
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return self.__name
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def __getinitargs__(self):
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return self.__offset,
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def utcoffset(self, dt):
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return self.__offset
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def tzname(self, dt):
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return self.__name
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def dst(self, dt):
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return timedelta(0)
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# This implementation is used for display purposes. It uses an approximation
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# for DST computations on dates >= 2038.
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# A similar implementation exists in django.utils.timezone. It's used for
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# timezone support (when USE_TZ = True) and focuses on correctness.
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class LocalTimezone(tzinfo):
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"Proxy timezone information from time module."
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def __init__(self, dt):
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tzinfo.__init__(self)
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self.__dt = dt
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self._tzname = self.tzname(dt)
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def __repr__(self):
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return force_str(self._tzname)
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def __getinitargs__(self):
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return self.__dt,
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def utcoffset(self, dt):
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if self._isdst(dt):
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return timedelta(seconds=-time.altzone)
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else:
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return timedelta(seconds=-time.timezone)
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def dst(self, dt):
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if self._isdst(dt):
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return timedelta(seconds=-time.altzone) - timedelta(seconds=-time.timezone)
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else:
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return timedelta(0)
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def tzname(self, dt):
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try:
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return force_text(time.tzname[self._isdst(dt)],
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DEFAULT_LOCALE_ENCODING)
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except UnicodeDecodeError:
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return None
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def _isdst(self, dt):
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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, 0)
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try:
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stamp = time.mktime(tt)
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except (OverflowError, ValueError):
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# 32 bit systems can't handle dates after Jan 2038, and certain
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# systems can't handle dates before ~1901-12-01:
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#
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# >>> time.mktime((1900, 1, 13, 0, 0, 0, 0, 0, 0))
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# OverflowError: mktime argument out of range
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# >>> time.mktime((1850, 1, 13, 0, 0, 0, 0, 0, 0))
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# ValueError: year out of range
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#
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# In this case, we fake the date, because we only care about the
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# DST flag.
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tt = (2037,) + tt[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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