psycopg2/lib/tz.py

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2005-10-18 09:42:00 +04:00
"""tzinfo implementations for psycopg2
This module holds twi different tzinfo implementations that can be used as
the 'tzinfo' argument to datetime constructors, directly passed to psycopg
functions or used to set the .tzinfo_factory attribute in cursors.
"""
# psycopg/tz.py - tzinfo implementation
#
# Copyright (C) 2003-2004 Federico Di Gregorio <fog@debian.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
import datetime
import time
ZERO = datetime.timedelta(0)
class FixedOffsetTimezone(datetime.tzinfo):
"""Fixed offset in minutes east from UTC.
This is exactly the implementation found in Python 2.3.x documentation,
with a small change to the __init__ method to allow for pickling and a
default name in the form 'sHH:MM' ('s' is the sign.)
"""
_name = None
_offset = ZERO
def __init__(self, offset=None, name=None):
if offset is not None:
self._offset = datetime.timedelta(minutes = offset)
if name is not None:
self._name = name
def utcoffset(self, dt):
return self._offset
def tzname(self, dt):
if self._name is not None:
return self._name
else:
seconds = self._offset.seconds + self._offset.days * 86400
hours, seconds = divmod(seconds, 3600)
minutes = seconds/60
if minutes:
return "%+03d:%d" % (hours, minutes)
else:
return "%+03d" % hours
def dst(self, dt):
return ZERO
STDOFFSET = datetime.timedelta(seconds = -time.timezone)
if time.daylight:
DSTOFFSET = datetime.timedelta(seconds = -time.altzone)
else:
DSTOFFSET = STDOFFSET
DSTDIFF = DSTOFFSET - STDOFFSET
class LocalTimezone(datetime.tzinfo):
"""Platform idea of local timezone.
This is the exact implementation from the Pyhton 2.3 documentation.
"""
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, -1)
stamp = time.mktime(tt)
tt = time.localtime(stamp)
return tt.tm_isdst > 0
LOCAL = LocalTimezone()
# TODO: pre-generate some interesting time zones?