Limnoria/src/utils/time.py
2021-12-07 23:30:16 +01:00

82 lines
2.8 KiB
Python

###
# Copyright (c) 2021, Valentin Lorentz
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions, and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions, and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# * Neither the name of the author of this software nor the name of
# contributors to this software may be used to endorse or promote products
# derived from this software without specific prior written consent.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
###
import re
import sys
if sys.version_info >= (3, 9):
import zoneinfo
else:
zoneinfo = None
try:
import pytz
except ImportError:
pytz = None
_IANA_TZ_RE = re.compile("([\w_-]+/)*[\w_-]+")
class TimezoneException(Exception):
pass
class MissingTimezoneLibrary(TimezoneException):
pass
class UnknownTimeZone(TimezoneException):
pass
def iana_timezone(name):
"""Returns a :class:datetime.tzinfo object, given an IANA timezone name,
eg. ``"Europe/Paris"``.
This uses :class:``zoneinfo.ZoneInfo`` if available,
:func:``pytz.timezone`` otherwise.
May raise instances of :exc:`TimezoneException`.
"""
if not _IANA_TZ_RE.match(name):
raise UnknownTimeZone(name)
if zoneinfo:
try:
return zoneinfo.ZoneInfo(name)
except zoneinfo.ZoneInfoNotFoundError as e:
raise UnknownTimeZone(e.args[0]) from None
elif pytz:
try:
timezone = pytz.timezone(name)
except pytz.UnknownTimeZoneError as e:
raise UnknownTimeZone(e.args[0]) from None
else:
raise MissingTimezoneLibrary(
"Could not find a timezone library. "
"Update Python to version 3.9 or newer, or install pytz."
)