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# -*- coding: utf-8 -*-
import warnings
import json
from tarfile import TarFile
from pkgutil import get_data
from io import BytesIO
from dateutil.tz import tzfile as _tzfile
__all__ = ["get_zonefile_instance", "gettz", "gettz_db_metadata"]
ZONEFILENAME = "dateutil-zoneinfo.tar.gz"
METADATA_FN = 'METADATA'
class tzfile(_tzfile):
def __reduce__(self):
return (gettz, (self._filename,))
def getzoneinfofile_stream():
try:
return BytesIO(get_data(__name__, ZONEFILENAME))
except IOError as e: # TODO switch to FileNotFoundError?
warnings.warn("I/O error({0}): {1}".format(e.errno, e.strerror))
return None
class ZoneInfoFile(object):
def __init__(self, zonefile_stream=None):
if zonefile_stream is not None:
with TarFile.open(fileobj=zonefile_stream) as tf:
self.zones = {zf.name: tzfile(tf.extractfile(zf), filename=zf.name)
for zf in tf.getmembers()
if zf.isfile() and zf.name != METADATA_FN}
# deal with links: They'll point to their parent object. Less
# waste of memory
links = {zl.name: self.zones[zl.linkname]
for zl in tf.getmembers() if
zl.islnk() or zl.issym()}
self.zones.update(links)
try:
metadata_json = tf.extractfile(tf.getmember(METADATA_FN))
metadata_str = metadata_json.read().decode('UTF-8')
self.metadata = json.loads(metadata_str)
except KeyError:
# no metadata in tar file
self.metadata = None
else:
self.zones = {}
self.metadata = None
def get(self, name, default=None):
"""
Wrapper for :func:`ZoneInfoFile.zones.get`. This is a convenience method
for retrieving zones from the zone dictionary.
:param name:
The name of the zone to retrieve. (Generally IANA zone names)
:param default:
The value to return in the event of a missing key.
.. versionadded:: 2.6.0
"""
return self.zones.get(name, default)
# The current API has gettz as a module function, although in fact it taps into
# a stateful class. So as a workaround for now, without changing the API, we
# will create a new "global" class instance the first time a user requests a
# timezone. Ugly, but adheres to the api.
#
# TODO: Remove after deprecation period.
_CLASS_ZONE_INSTANCE = []
def get_zonefile_instance(new_instance=False):
"""
This is a convenience function which provides a :class:`ZoneInfoFile`
instance using the data provided by the ``dateutil`` package. By default, it
caches a single instance of the ZoneInfoFile object and returns that.
:param new_instance:
If ``True``, a new instance of :class:`ZoneInfoFile` is instantiated and
used as the cached instance for the next call. Otherwise, new instances
are created only as necessary.
:return:
Returns a :class:`ZoneInfoFile` object.
.. versionadded:: 2.6
"""
if new_instance:
zif = None
else:
zif = getattr(get_zonefile_instance, '_cached_instance', None)
if zif is None:
zif = ZoneInfoFile(getzoneinfofile_stream())
get_zonefile_instance._cached_instance = zif
return zif
def gettz(name):
"""
This retrieves a time zone from the local zoneinfo tarball that is packaged
with dateutil.
:param name:
An IANA-style time zone name, as found in the zoneinfo file.
:return:
Returns a :class:`dateutil.tz.tzfile` time zone object.
.. warning::
It is generally inadvisable to use this function, and it is only
provided for API compatibility with earlier versions. This is *not*
equivalent to ``dateutil.tz.gettz()``, which selects an appropriate
time zone based on the inputs, favoring system zoneinfo. This is ONLY
for accessing the dateutil-specific zoneinfo (which may be out of
date compared to the system zoneinfo).
.. deprecated:: 2.6
If you need to use a specific zoneinfofile over the system zoneinfo,
instantiate a :class:`dateutil.zoneinfo.ZoneInfoFile` object and call
:func:`dateutil.zoneinfo.ZoneInfoFile.get(name)` instead.
Use :func:`get_zonefile_instance` to retrieve an instance of the
dateutil-provided zoneinfo.
"""
warnings.warn("zoneinfo.gettz() will be removed in future versions, "
"to use the dateutil-provided zoneinfo files, instantiate a "
"ZoneInfoFile object and use ZoneInfoFile.zones.get() "
"instead. See the documentation for details.",
DeprecationWarning)
if len(_CLASS_ZONE_INSTANCE) == 0:
_CLASS_ZONE_INSTANCE.append(ZoneInfoFile(getzoneinfofile_stream()))
return _CLASS_ZONE_INSTANCE[0].zones.get(name)
def gettz_db_metadata():
""" Get the zonefile metadata
See `zonefile_metadata`_
:returns:
A dictionary with the database metadata
.. deprecated:: 2.6
See deprecation warning in :func:`zoneinfo.gettz`. To get metadata,
query the attribute ``zoneinfo.ZoneInfoFile.metadata``.
"""
warnings.warn("zoneinfo.gettz_db_metadata() will be removed in future "
"versions, to use the dateutil-provided zoneinfo files, "
"ZoneInfoFile object and query the 'metadata' attribute "
"instead. See the documentation for details.",
DeprecationWarning)
if len(_CLASS_ZONE_INSTANCE) == 0:
_CLASS_ZONE_INSTANCE.append(ZoneInfoFile(getzoneinfofile_stream()))
return _CLASS_ZONE_INSTANCE[0].metadata
|
