psycopg2/lib/tz.py
2004-10-19 03:17:12 +00:00

95 lines
2.6 KiB
Python

# 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?