app/django/utils/tzinfo.py
author Sverre Rabbelier <srabbelier@gmail.com>
Thu, 05 Feb 2009 23:52:27 +0000
changeset 1230 b1b1897e4df1
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Cleanup in org_app and replace ReferenceProperty with LinkProperty Using LinkProperty allows the org to host their idea's list on Melange through the Document system, and then specify the URL of that document. This also makes it possible for the orgs to specify a document that is not hosted on Melange. Patch by: Sverre Rabbelier

"Implementation of tzinfo classes for use with datetime.datetime."

import locale
import time
from datetime import timedelta, tzinfo
from django.utils.encoding import smart_unicode

try:
    DEFAULT_ENCODING = locale.getdefaultlocale()[1] or 'ascii'
except:
    # Any problems at all determining the locale and we fallback. See #5846.
    DEFAULT_ENCODING = 'ascii'

class FixedOffset(tzinfo):
    "Fixed offset in minutes east from UTC."
    def __init__(self, offset):
        if isinstance(offset, timedelta):
            self.__offset = offset
            offset = self.__offset.seconds // 60
        else:
            self.__offset = timedelta(minutes=offset)

        self.__name = u"%+03d%02d" % (offset / 60, offset % 60)

    def __repr__(self):
        return self.__name

    def utcoffset(self, dt):
        return self.__offset

    def tzname(self, dt):
        return self.__name

    def dst(self, dt):
        return timedelta(0)

class LocalTimezone(tzinfo):
    "Proxy timezone information from time module."
    def __init__(self, dt):
        tzinfo.__init__(self)
        self._tzname = self.tzname(dt)

    def __repr__(self):
        return self._tzname

    def utcoffset(self, dt):
        if self._isdst(dt):
            return timedelta(seconds=-time.altzone)
        else:
            return timedelta(seconds=-time.timezone)

    def dst(self, dt):
        if self._isdst(dt):
            return timedelta(seconds=-time.altzone) - timedelta(seconds=-time.timezone)
        else:
            return timedelta(0)

    def tzname(self, dt):
        try:
            return smart_unicode(time.tzname[self._isdst(dt)], DEFAULT_ENCODING)
        except UnicodeDecodeError:
            return None

    def _isdst(self, dt):
        tt = (dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second, dt.weekday(), 0, -1)
        try:
            stamp = time.mktime(tt)
        except (OverflowError, ValueError):
            # 32 bit systems can't handle dates after Jan 2038, and certain
            # systems can't handle dates before ~1901-12-01:
            #
            # >>> time.mktime((1900, 1, 13, 0, 0, 0, 0, 0, 0))
            # OverflowError: mktime argument out of range
            # >>> time.mktime((1850, 1, 13, 0, 0, 0, 0, 0, 0))
            # ValueError: year out of range
            #
            # In this case, we fake the date, because we only care about the
            # DST flag.
            tt = (2037,) + tt[1:]
            stamp = time.mktime(tt)
        tt = time.localtime(stamp)
        return tt.tm_isdst > 0