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# This code was kindly provided by Jeffrey Harris.
import _winreg
import struct
import datetime
TIMEZONESKEY = r"SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones"
TIMEZONEINFOKEY = r"SYSTEM\CurrentControlSet\Control\TimeZoneInformation"
HANDLE = _winreg.ConnectRegistry(None, _winreg.HKEY_LOCAL_MACHINE)
LOCALKEY = _winreg.OpenKey(HANDLE, TIMEZONEINFOKEY)
TZPARENT = _winreg.OpenKey(HANDLE, TIMEZONESKEY)
TZPARENTSIZE = _winreg.QueryInfoKey(TZPARENT)[0]
ONEWEEK = datetime.timedelta(7)
class tzwin(datetime.tzinfo):
"""tzinfo class based on win32's timezones available in the registry.
>>> local = tzwin('Central Standard Time')
>>> oct1 = datetime.datetime(month=10, year=2004, day=1, tzinfo=local)
>>> dec1 = datetime.datetime(month=12, year=2004, day=1, tzinfo=local)
>>> oct1.dst()
datetime.timedelta(0, 3600)
>>> dec1.dst()
datetime.timedelta(0)
>>> braz = tzwin('E. South America Standard Time')
>>> braz.dst(oct1)
datetime.timedelta(0)
>>> braz.dst(dec1)
datetime.timedelta(0, 3600)
"""
def __init__(self, name):
self._info = _tzwininfo(name)
def utcoffset(self, dt):
if self._isdst(dt):
return datetime.timedelta(minutes=self._info.dstoffset)
else:
return datetime.timedelta(minutes=self._info.stdoffset)
def dst(self, dt):
if self._isdst(dt):
minutes = self._info.dstoffset - self._info.stdoffset
return datetime.timedelta(minutes=minutes)
else:
return datetime.timedelta(0)
def tzname(self, dt):
if self._isdst(dt):
return self._info.dstname
else:
return self._info.stdname
def list():
"""Return a list of all time zones known to the system."""
return [_winreg.EnumKey(TZPARENT, i) for i in range(TZPARENTSIZE)]
list = staticmethod(list)
def _isdst(self, dt):
i = self._info
dston = picknthweekday(dt.year, i.dstmonth, i.dstdayofweek,
i.dsthour, i.dstminute, i.dstweeknumber)
dstoff = picknthweekday(dt.year, i.stdmonth, i.stddayofweek,
i.stdhour, i.stdminute, i.stdweeknumber)
if dston < dstoff:
return dston <= dt.replace(tzinfo=None) < dstoff
else:
return not dstoff <= dt.replace(tzinfo=None) < dston
def __repr__(self):
return "tzwin(%s)" % repr(self._info.display)
__reduce__ = object.__reduce__
class _tzwininfo(object):
"""Read a registry key for a timezone, expose its contents."""
def __init__(self, path):
"""Load path, or if path is empty, load local time."""
if path:
keydict=valuestodict(_winreg.OpenKey(TZPARENT, path))
self.display = keydict['Display']
self.dstname = keydict['Dlt']
self.stdname = keydict['Std']
#see http://ww_winreg.jsiinc.com/SUBA/tip0300/rh0398.htm
tup = struct.unpack('=3l16h', keydict['TZI'])
self.stdoffset = -tup[0]-tup[1] #Bias + StandardBias * -1
self.dstoffset = self.stdoffset - tup[2] # + DaylightBias * -1
offset=3
self.stdmonth = tup[1 + offset]
self.stddayofweek = tup[2 + offset] #Sunday=0
self.stdweeknumber = tup[3 + offset] #Last = 5
self.stdhour = tup[4 + offset]
self.stdminute = tup[5 + offset]
offset=11
self.dstmonth = tup[1 + offset]
self.dstdayofweek = tup[2 + offset] #Sunday=0
self.dstweeknumber = tup[3 + offset] #Last = 5
self.dsthour = tup[4 + offset]
self.dstminute = tup[5 + offset]
else:
keydict=valuestodict(LOCALKEY)
self.stdname = keydict['StandardName']
self.dstname = keydict['DaylightName']
sourcekey=_winreg.OpenKey(TZPARENT, self.stdname)
self.display = valuestodict(sourcekey)['Display']
self.stdoffset = -keydict['Bias']-keydict['StandardBias']
self.dstoffset = self.stdoffset - keydict['DaylightBias']
#see http://ww_winreg.jsiinc.com/SUBA/tip0300/rh0398.htm
tup = struct.unpack('=8h', keydict['StandardStart'])
offset=0
self.stdmonth = tup[1 + offset]
self.stddayofweek = tup[2 + offset] #Sunday=0
self.stdweeknumber = tup[3 + offset] #Last = 5
self.stdhour = tup[4 + offset]
self.stdminute = tup[5 + offset]
tup = struct.unpack('=8h', keydict['DaylightStart'])
self.dstmonth = tup[1 + offset]
self.dstdayofweek = tup[2 + offset] #Sunday=0
self.dstweeknumber = tup[3 + offset] #Last = 5
self.dsthour = tup[4 + offset]
self.dstminute = tup[5 + offset]
def picknthweekday(year, month, dayofweek, hour, minute, whichweek):
"""dayofweek == 0 means Sunday, whichweek 5 means last instance"""
first = datetime.datetime(year, month, 1, hour, minute)
weekdayone = first.replace(day=((dayofweek-first.isoweekday())%7+1))
for n in xrange(whichweek):
dt = weekdayone+(whichweek-n)*ONEWEEK
if dt.month == month:
return dt
def valuestodict(key):
"""Convert a registry key's values to a dictionary."""
dict={}
size=_winreg.QueryInfoKey(key)[1]
for i in xrange(size):
dict[_winreg.EnumValue(key, i)[0]]=_winreg.EnumValue(key, i)[1]
return dict
def _test():
import tzwin, doctest
doctest.testmod(tzwin, verbose=0)
if __name__ == '__main__':
_test()
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