# -*- coding: utf-8 -*- """ This module offers timezone implementations subclassing the abstract :py:class:`datetime.tzinfo` type. There are classes to handle tzfile format files (usually are in :file:`/etc/localtime`, :file:`/usr/share/zoneinfo`, etc), TZ environment string (in all known formats), given ranges (with help from relative deltas), local machine timezone, fixed offset timezone, and UTC timezone. """ import bisect import datetime import os import struct import sys import time import warnings import weakref from collections import OrderedDict import six from six import string_types from six.moves import _thread from .. import _tzdata_impl from . import _tzpath from ._common import ( _tzinfo, _validate_fromutc_inputs, enfold, tzname_in_python2, tzrangebase, ) from ._factories import _TzOffsetFactory, _TzSingleton, _TzStrFactory from ._tzfile import tzfile try: from .win import tzwin, tzwinlocal except ImportError: tzwin = tzwinlocal = None # For warning about rounding tzinfo from warnings import warn ZERO = datetime.timedelta(0) EPOCH = datetime.datetime(1970, 1, 1, 0, 0) @six.add_metaclass(_TzSingleton) class tzutc(datetime.tzinfo): """ This is a tzinfo object that represents the UTC time zone. **Examples:** .. doctest:: >>> from datetime import * >>> from dateutil.tz import * >>> datetime.now() datetime.datetime(2003, 9, 27, 9, 40, 1, 521290) >>> datetime.now(tzutc()) datetime.datetime(2003, 9, 27, 12, 40, 12, 156379, tzinfo=tzutc()) >>> datetime.now(tzutc()).tzname() 'UTC' .. versionchanged:: 2.7.0 ``tzutc()`` is now a singleton, so the result of ``tzutc()`` will always return the same object. .. doctest:: >>> from dateutil.tz import tzutc, UTC >>> tzutc() is tzutc() True >>> tzutc() is UTC True """ def utcoffset(self, dt): return ZERO def dst(self, dt): return ZERO @tzname_in_python2 def tzname(self, dt): return "UTC" def is_ambiguous(self, dt): """ Whether or not the "wall time" of a given datetime is ambiguous in this zone. :param dt: A :py:class:`datetime.datetime`, naive or time zone aware. :return: Returns ``True`` if ambiguous, ``False`` otherwise. .. versionadded:: 2.6.0 """ return False @_validate_fromutc_inputs def fromutc(self, dt): """ Fast track version of fromutc() returns the original ``dt`` object for any valid :py:class:`datetime.datetime` object. """ return dt def __eq__(self, other): if not isinstance(other, (tzutc, tzoffset)): return NotImplemented return (isinstance(other, tzutc) or (isinstance(other, tzoffset) and other._offset == ZERO)) __hash__ = None def __ne__(self, other): return not (self == other) def __repr__(self): return "%s()" % self.__class__.__name__ __reduce__ = object.__reduce__ #: Convenience constant providing a :class:`tzutc()` instance #: #: .. versionadded:: 2.7.0 UTC = tzutc() @six.add_metaclass(_TzOffsetFactory) class tzoffset(datetime.tzinfo): """ A simple class for representing a fixed offset from UTC. :param name: The timezone name, to be returned when ``tzname()`` is called. :param offset: The time zone offset in seconds, or (since version 2.6.0, represented as a :py:class:`datetime.timedelta` object). """ def __init__(self, name, offset): self._name = name try: # Allow a timedelta offset = offset.total_seconds() except (TypeError, AttributeError): pass self._offset = datetime.timedelta(seconds=_get_supported_offset(offset)) def utcoffset(self, dt): return self._offset def dst(self, dt): return ZERO @tzname_in_python2 def tzname(self, dt): return self._name @_validate_fromutc_inputs def fromutc(self, dt): return dt + self._offset def is_ambiguous(self, dt): """ Whether or not the "wall time" of a given datetime is ambiguous in this zone. :param dt: A :py:class:`datetime.datetime`, naive or time zone aware. :return: Returns ``True`` if ambiguous, ``False`` otherwise. .. versionadded:: 2.6.0 """ return False def __eq__(self, other): if not isinstance(other, tzoffset): return NotImplemented return self._offset == other._offset __hash__ = None def __ne__(self, other): return not (self == other) def __repr__(self): return "%s(%s, %s)" % (self.__class__.__name__, repr(self._name), int(self._offset.total_seconds())) __reduce__ = object.__reduce__ class tzlocal(_tzinfo): """ A :class:`tzinfo` subclass built around the ``time`` timezone functions. """ def __init__(self): super(tzlocal, self).__init__() self._std_offset = datetime.timedelta(seconds=-time.timezone) if time.daylight: self._dst_offset = datetime.timedelta(seconds=-time.altzone) else: self._dst_offset = self._std_offset self._dst_saved = self._dst_offset - self._std_offset self._hasdst = bool(self._dst_saved) self._tznames = tuple(time.tzname) def utcoffset(self, dt): if dt is None and self._hasdst: return None if self._isdst(dt): return self._dst_offset else: return self._std_offset def dst(self, dt): if dt is None and self._hasdst: return None if self._isdst(dt): return self._dst_offset - self._std_offset else: return ZERO @tzname_in_python2 def tzname(self, dt): return self._tznames[self._isdst(dt)] def is_ambiguous(self, dt): """ Whether or not the "wall time" of a given datetime is ambiguous in this zone. :param dt: A :py:class:`datetime.datetime`, naive or time zone aware. :return: Returns ``True`` if ambiguous, ``False`` otherwise. .. versionadded:: 2.6.0 """ naive_dst = self._naive_is_dst(dt) return (not naive_dst and (naive_dst != self._naive_is_dst(dt - self._dst_saved))) def _naive_is_dst(self, dt): timestamp = _datetime_to_timestamp(dt) return time.localtime(timestamp + time.timezone).tm_isdst def _isdst(self, dt, fold_naive=True): # We can't use mktime here. It is unstable when deciding if # the hour near to a change is DST or not. # # timestamp = time.mktime((dt.year, dt.month, dt.day, dt.hour, # dt.minute, dt.second, dt.weekday(), 0, -1)) # return time.localtime(timestamp).tm_isdst # # The code above yields the following result: # # >>> import tz, datetime # >>> t = tz.tzlocal() # >>> datetime.datetime(2003,2,15,23,tzinfo=t).tzname() # 'BRDT' # >>> datetime.datetime(2003,2,16,0,tzinfo=t).tzname() # 'BRST' # >>> datetime.datetime(2003,2,15,23,tzinfo=t).tzname() # 'BRST' # >>> datetime.datetime(2003,2,15,22,tzinfo=t).tzname() # 'BRDT' # >>> datetime.datetime(2003,2,15,23,tzinfo=t).tzname() # 'BRDT' # # Here is a more stable implementation: # if not self._hasdst: return False # Check for ambiguous times: dstval = self._naive_is_dst(dt) fold = getattr(dt, 'fold', None) if self.is_ambiguous(dt): if fold is not None: return not self._fold(dt) else: return True return dstval def __eq__(self, other): if isinstance(other, tzlocal): return (self._std_offset == other._std_offset and self._dst_offset == other._dst_offset) elif isinstance(other, tzutc): return (not self._hasdst and self._tznames[0] in {'UTC', 'GMT'} and self._std_offset == ZERO) elif isinstance(other, tzoffset): return (not self._hasdst and self._tznames[0] == other._name and self._std_offset == other._offset) else: return NotImplemented __hash__ = None def __ne__(self, other): return not (self == other) def __repr__(self): return "%s()" % self.__class__.__name__ __reduce__ = object.__reduce__ class tzrange(tzrangebase): """ The ``tzrange`` object is a time zone specified by a set of offsets and abbreviations, equivalent to the way the ``TZ`` variable can be specified in POSIX-like systems, but using Python delta objects to specify DST start, end and offsets. :param stdabbr: The abbreviation for standard time (e.g. ``'EST'``). :param stdoffset: An integer or :class:`datetime.timedelta` object or equivalent specifying the base offset from UTC. If unspecified, +00:00 is used. :param dstabbr: The abbreviation for DST / "Summer" time (e.g. ``'EDT'``). If specified, with no other DST information, DST is assumed to occur and the default behavior or ``dstoffset``, ``start`` and ``end`` is used. If unspecified and no other DST information is specified, it is assumed that this zone has no DST. If this is unspecified and other DST information is *is* specified, DST occurs in the zone but the time zone abbreviation is left unchanged. :param dstoffset: A an integer or :class:`datetime.timedelta` object or equivalent specifying the UTC offset during DST. If unspecified and any other DST information is specified, it is assumed to be the STD offset +1 hour. :param start: A :class:`relativedelta.relativedelta` object or equivalent specifying the time and time of year that daylight savings time starts. To specify, for example, that DST starts at 2AM on the 2nd Sunday in March, pass: ``relativedelta(hours=2, month=3, day=1, weekday=SU(+2))`` If unspecified and any other DST information is specified, the default value is 2 AM on the first Sunday in April. :param end: A :class:`relativedelta.relativedelta` object or equivalent representing the time and time of year that daylight savings time ends, with the same specification method as in ``start``. One note is that this should point to the first time in the *standard* zone, so if a transition occurs at 2AM in the DST zone and the clocks are set back 1 hour to 1AM, set the ``hours`` parameter to +1. **Examples:** .. testsetup:: tzrange from dateutil.tz import tzrange, tzstr .. doctest:: tzrange >>> tzstr('EST5EDT') == tzrange("EST", -18000, "EDT") True >>> from dateutil.relativedelta import * >>> range1 = tzrange("EST", -18000, "EDT") >>> range2 = tzrange("EST", -18000, "EDT", -14400, ... relativedelta(hours=+2, month=4, day=1, ... weekday=SU(+1)), ... relativedelta(hours=+1, month=10, day=31, ... weekday=SU(-1))) >>> tzstr('EST5EDT') == range1 == range2 True """ def __init__(self, stdabbr, stdoffset=None, dstabbr=None, dstoffset=None, start=None, end=None): global relativedelta from dateutil import relativedelta self._std_abbr = stdabbr self._dst_abbr = dstabbr try: stdoffset = stdoffset.total_seconds() except (TypeError, AttributeError): pass try: dstoffset = dstoffset.total_seconds() except (TypeError, AttributeError): pass if stdoffset is not None: self._std_offset = datetime.timedelta(seconds=stdoffset) else: self._std_offset = ZERO if dstoffset is not None: self._dst_offset = datetime.timedelta(seconds=dstoffset) elif dstabbr and stdoffset is not None: self._dst_offset = self._std_offset + datetime.timedelta(hours=+1) else: self._dst_offset = ZERO if dstabbr and start is None: self._start_delta = relativedelta.relativedelta( hours=+2, month=4, day=1, weekday=relativedelta.SU(+1)) else: self._start_delta = start if dstabbr and end is None: self._end_delta = relativedelta.relativedelta( hours=+1, month=10, day=31, weekday=relativedelta.SU(-1)) else: self._end_delta = end self._dst_base_offset_ = self._dst_offset - self._std_offset self.hasdst = bool(self._start_delta) def transitions(self, year): """ For a given year, get the DST on and off transition times, expressed always on the standard time side. For zones with no transitions, this function returns ``None``. :param year: The year whose transitions you would like to query. :return: Returns a :class:`tuple` of :class:`datetime.datetime` objects, ``(dston, dstoff)`` for zones with an annual DST transition, or ``None`` for fixed offset zones. """ if not self.hasdst: return None base_year = datetime.datetime(year, 1, 1) start = base_year + self._start_delta end = base_year + self._end_delta return (start, end) def __eq__(self, other): if not isinstance(other, tzrange): return NotImplemented return (self._std_abbr == other._std_abbr and self._dst_abbr == other._dst_abbr and self._std_offset == other._std_offset and self._dst_offset == other._dst_offset and self._start_delta == other._start_delta and self._end_delta == other._end_delta) @property def _dst_base_offset(self): return self._dst_base_offset_ @six.add_metaclass(_TzStrFactory) class tzstr(tzrange): """ ``tzstr`` objects are time zone objects specified by a time-zone string as it would be passed to a ``TZ`` variable on POSIX-style systems (see the `GNU C Library: TZ Variable`_ for more details). There is one notable exception, which is that POSIX-style time zones use an inverted offset format, so normally ``GMT+3`` would be parsed as an offset 3 hours *behind* GMT. The ``tzstr`` time zone object will parse this as an offset 3 hours *ahead* of GMT. If you would like to maintain the POSIX behavior, pass a ``True`` value to ``posix_offset``. The :class:`tzrange` object provides the same functionality, but is specified using :class:`relativedelta.relativedelta` objects. rather than strings. :param s: A time zone string in ``TZ`` variable format. This can be a :class:`bytes` (2.x: :class:`str`), :class:`str` (2.x: :class:`unicode`) or a stream emitting unicode characters (e.g. :class:`StringIO`). :param posix_offset: Optional. If set to ``True``, interpret strings such as ``GMT+3`` or ``UTC+3`` as being 3 hours *behind* UTC rather than ahead, per the POSIX standard. .. caution:: Prior to version 2.7.0, this function also supported time zones in the format: * ``EST5EDT,4,0,6,7200,10,0,26,7200,3600`` * ``EST5EDT,4,1,0,7200,10,-1,0,7200,3600`` This format is non-standard and has been deprecated; this function will raise a :class:`DeprecatedTZFormatWarning` until support is removed in a future version. .. _`GNU C Library: TZ Variable`: https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html """ def __init__(self, s, posix_offset=False): global parser from dateutil.parser import _parser as parser self._s = s res = parser._parsetz(s) if res is None or res.any_unused_tokens: raise ValueError("unknown string format") # Here we break the compatibility with the TZ variable handling. # GMT-3 actually *means* the timezone -3. if res.stdabbr in ("GMT", "UTC") and not posix_offset: res.stdoffset *= -1 # We must initialize it first, since _delta() needs # _std_offset and _dst_offset set. Use False in start/end # to avoid building it two times. tzrange.__init__(self, res.stdabbr, res.stdoffset, res.dstabbr, res.dstoffset, start=False, end=False) if not res.dstabbr: self._start_delta = None self._end_delta = None else: self._start_delta = self._delta(res.start) if self._start_delta: self._end_delta = self._delta(res.end, isend=1) self.hasdst = bool(self._start_delta) def _delta(self, x, isend=0): from dateutil import relativedelta kwargs = {} if x.month is not None: kwargs["month"] = x.month if x.weekday is not None: kwargs["weekday"] = relativedelta.weekday(x.weekday, x.week) if x.week > 0: kwargs["day"] = 1 else: kwargs["day"] = 31 elif x.day: kwargs["day"] = x.day elif x.yday is not None: kwargs["yearday"] = x.yday elif x.jyday is not None: kwargs["nlyearday"] = x.jyday if not kwargs: # Default is to start on first sunday of april, and end # on last sunday of october. if not isend: kwargs["month"] = 4 kwargs["day"] = 1 kwargs["weekday"] = relativedelta.SU(+1) else: kwargs["month"] = 10 kwargs["day"] = 31 kwargs["weekday"] = relativedelta.SU(-1) if x.time is not None: kwargs["seconds"] = x.time else: # Default is 2AM. kwargs["seconds"] = 7200 if isend: # Convert to standard time, to follow the documented way # of working with the extra hour. See the documentation # of the tzinfo class. delta = self._dst_offset - self._std_offset kwargs["seconds"] -= delta.seconds + delta.days * 86400 return relativedelta.relativedelta(**kwargs) def __repr__(self): return "%s(%s)" % (self.__class__.__name__, repr(self._s)) class _tzicalvtzcomp(object): def __init__(self, tzoffsetfrom, tzoffsetto, isdst, tzname=None, rrule=None): self.tzoffsetfrom = datetime.timedelta(seconds=tzoffsetfrom) self.tzoffsetto = datetime.timedelta(seconds=tzoffsetto) self.tzoffsetdiff = self.tzoffsetto - self.tzoffsetfrom self.isdst = isdst self.tzname = tzname self.rrule = rrule class _tzicalvtz(_tzinfo): def __init__(self, tzid, comps=[]): super(_tzicalvtz, self).__init__() self._tzid = tzid self._comps = comps self._cachedate = [] self._cachecomp = [] self._cache_lock = _thread.allocate_lock() def _find_comp(self, dt): if len(self._comps) == 1: return self._comps[0] dt = dt.replace(tzinfo=None) try: with self._cache_lock: return self._cachecomp[self._cachedate.index( (dt, self._fold(dt)))] except ValueError: pass lastcompdt = None lastcomp = None for comp in self._comps: compdt = self._find_compdt(comp, dt) if compdt and (not lastcompdt or lastcompdt < compdt): lastcompdt = compdt lastcomp = comp if not lastcomp: # RFC says nothing about what to do when a given # time is before the first onset date. We'll look for the # first standard component, or the first component, if # none is found. for comp in self._comps: if not comp.isdst: lastcomp = comp break else: lastcomp = comp[0] with self._cache_lock: self._cachedate.insert(0, (dt, self._fold(dt))) self._cachecomp.insert(0, lastcomp) if len(self._cachedate) > 10: self._cachedate.pop() self._cachecomp.pop() return lastcomp def _find_compdt(self, comp, dt): if comp.tzoffsetdiff < ZERO and self._fold(dt): dt -= comp.tzoffsetdiff compdt = comp.rrule.before(dt, inc=True) return compdt def utcoffset(self, dt): if dt is None: return None return self._find_comp(dt).tzoffsetto def dst(self, dt): comp = self._find_comp(dt) if comp.isdst: return comp.tzoffsetdiff else: return ZERO @tzname_in_python2 def tzname(self, dt): return self._find_comp(dt).tzname def __repr__(self): return "" % repr(self._tzid) __reduce__ = object.__reduce__ class tzical(object): """ This object is designed to parse an iCalendar-style ``VTIMEZONE`` structure as set out in `RFC 5545`_ Section 4.6.5 into one or more `tzinfo` objects. :param `fileobj`: A file or stream in iCalendar format, which should be UTF-8 encoded with CRLF endings. .. _`RFC 5545`: https://tools.ietf.org/html/rfc5545 """ def __init__(self, fileobj): global rrule from dateutil import rrule if isinstance(fileobj, string_types): self._s = fileobj # ical should be encoded in UTF-8 with CRLF fileobj = open(fileobj, 'r') else: self._s = getattr(fileobj, 'name', repr(fileobj)) fileobj = _nullcontext(fileobj) self._vtz = {} with fileobj as fobj: self._parse_rfc(fobj.read()) def keys(self): """ Retrieves the available time zones as a list. """ return list(self._vtz.keys()) def get(self, tzid=None): """ Retrieve a :py:class:`datetime.tzinfo` object by its ``tzid``. :param tzid: If there is exactly one time zone available, omitting ``tzid`` or passing :py:const:`None` value returns it. Otherwise a valid key (which can be retrieved from :func:`keys`) is required. :raises ValueError: Raised if ``tzid`` is not specified but there are either more or fewer than 1 zone defined. :returns: Returns either a :py:class:`datetime.tzinfo` object representing the relevant time zone or :py:const:`None` if the ``tzid`` was not found. """ if tzid is None: if len(self._vtz) == 0: raise ValueError("no timezones defined") elif len(self._vtz) > 1: raise ValueError("more than one timezone available") tzid = next(iter(self._vtz)) return self._vtz.get(tzid) def _parse_offset(self, s): s = s.strip() if not s: raise ValueError("empty offset") if s[0] in ('+', '-'): signal = (-1, +1)[s[0] == '+'] s = s[1:] else: signal = +1 if len(s) == 4: return (int(s[:2]) * 3600 + int(s[2:]) * 60) * signal elif len(s) == 6: return (int(s[:2]) * 3600 + int(s[2:4]) * 60 + int(s[4:])) * signal else: raise ValueError("invalid offset: " + s) def _parse_rfc(self, s): lines = s.splitlines() if not lines: raise ValueError("empty string") # Unfold i = 0 while i < len(lines): line = lines[i].rstrip() if not line: del lines[i] elif i > 0 and line[0] == " ": lines[i-1] += line[1:] del lines[i] else: i += 1 tzid = None comps = [] invtz = False comptype = None for line in lines: if not line: continue name, value = line.split(':', 1) parms = name.split(';') if not parms: raise ValueError("empty property name") name = parms[0].upper() parms = parms[1:] if invtz: if name == "BEGIN": if value in ("STANDARD", "DAYLIGHT"): # Process component pass else: raise ValueError("unknown component: "+value) comptype = value founddtstart = False tzoffsetfrom = None tzoffsetto = None rrulelines = [] tzname = None elif name == "END": if value == "VTIMEZONE": if comptype: raise ValueError("component not closed: "+comptype) if not tzid: raise ValueError("mandatory TZID not found") if not comps: raise ValueError( "at least one component is needed") # Process vtimezone self._vtz[tzid] = _tzicalvtz(tzid, comps) invtz = False elif value == comptype: if not founddtstart: raise ValueError("mandatory DTSTART not found") if tzoffsetfrom is None: raise ValueError( "mandatory TZOFFSETFROM not found") if tzoffsetto is None: raise ValueError( "mandatory TZOFFSETFROM not found") # Process component rr = None if rrulelines: rr = rrule.rrulestr("\n".join(rrulelines), compatible=True, ignoretz=True, cache=True) comp = _tzicalvtzcomp(tzoffsetfrom, tzoffsetto, (comptype == "DAYLIGHT"), tzname, rr) comps.append(comp) comptype = None else: raise ValueError("invalid component end: "+value) elif comptype: if name == "DTSTART": # DTSTART in VTIMEZONE takes a subset of valid RRULE # values under RFC 5545. for parm in parms: if parm != 'VALUE=DATE-TIME': msg = ('Unsupported DTSTART param in ' + 'VTIMEZONE: ' + parm) raise ValueError(msg) rrulelines.append(line) founddtstart = True elif name in ("RRULE", "RDATE", "EXRULE", "EXDATE"): rrulelines.append(line) elif name == "TZOFFSETFROM": if parms: raise ValueError( "unsupported %s parm: %s " % (name, parms[0])) tzoffsetfrom = self._parse_offset(value) elif name == "TZOFFSETTO": if parms: raise ValueError( "unsupported TZOFFSETTO parm: "+parms[0]) tzoffsetto = self._parse_offset(value) elif name == "TZNAME": if parms: raise ValueError( "unsupported TZNAME parm: "+parms[0]) tzname = value elif name == "COMMENT": pass else: raise ValueError("unsupported property: "+name) else: if name == "TZID": if parms: raise ValueError( "unsupported TZID parm: "+parms[0]) tzid = value elif name in ("TZURL", "LAST-MODIFIED", "COMMENT"): pass else: raise ValueError("unsupported property: "+name) elif name == "BEGIN" and value == "VTIMEZONE": tzid = None comps = [] invtz = True def __repr__(self): return "%s(%s)" % (self.__class__.__name__, repr(self._s)) TZFILES = ["/etc/localtime", "localtime"] def __get_gettz(): tzlocal_classes = (tzlocal,) if tzwinlocal is not None: tzlocal_classes += (tzwinlocal,) class GettzFunc(object): """ Retrieve a time zone object from a string representation This function is intended to retrieve the :py:class:`tzinfo` subclass that best represents the time zone that would be used if a POSIX `TZ variable`_ were set to the same value. If no argument or an empty string is passed to ``gettz``, local time is returned: .. code-block:: python3 >>> gettz() tzfile('/etc/localtime') This function is also the preferred way to map IANA tz database keys to :class:`tzfile` objects. It searches for these keys in the following order: 1. On the search path defined in :data:`TZPATH`. 2. In the `tzdata `_ Python package. 3. Using the system-specific mechanisms (e.g. the Windows registry). .. code-block:: python3 >>> gettz('Pacific/Kiritimati') tzfile('/usr/share/zoneinfo/Pacific/Kiritimati') On Windows, the standard is extended to include the Windows-specific zone names provided by the operating system: .. code-block:: python3 >>> gettz('Egypt Standard Time') tzwin('Egypt Standard Time') Passing a GNU ``TZ`` style string time zone specification returns a :class:`tzstr` object: .. code-block:: python3 >>> gettz('AEST-10AEDT-11,M10.1.0/2,M4.1.0/3') tzstr('AEST-10AEDT-11,M10.1.0/2,M4.1.0/3') :param name: A time zone name (IANA, or, on Windows, Windows keys), location of a ``tzfile(5)`` zoneinfo file or ``TZ`` variable style time zone specifier. An empty string, no argument or ``None`` is interpreted as local time. :return: Returns an instance of one of ``dateutil``'s :py:class:`tzinfo` subclasses. .. versionchanged:: 2.7.0 After version 2.7.0, any two calls to ``gettz`` using the same input strings will return the same object: .. code-block:: python3 >>> tz.gettz('America/Chicago') is tz.gettz('America/Chicago') True In addition to improving performance, this ensures that `"same zone" semantics`_ are used for datetimes in the same zone. .. _`TZ variable`: https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html .. _`"same zone" semantics`: https://blog.ganssle.io/articles/2018/02/aware-datetime-arithmetic.html """ def __init__(self): self.__instances = weakref.WeakValueDictionary() self.__strong_cache_size = 8 self.__strong_cache = OrderedDict() self._cache_lock = _thread.allocate_lock() def __call__(self, name=None): with self._cache_lock: rv = self.__instances.get(name, None) if rv is None: # TODO: This holds the cache lock while nocache() reads # the file, so a slow lookup (e.g. walking TZPATH on a # network file system) blocks every other gettz call, # including cache hits for unrelated keys. rv = self.nocache(name=name) if not (name is None or isinstance(rv, tzlocal_classes) or rv is None): # tzlocal is slightly more complicated than the other # time zone providers because it depends on environment # at construction time, so don't cache that. # # We also cannot store weak references to None, so we # will also not store that. self.__instances[name] = rv else: # No need for strong caching, return immediately return rv self.__strong_cache[name] = self.__strong_cache.pop(name, rv) if len(self.__strong_cache) > self.__strong_cache_size: self.__strong_cache.popitem(last=False) return rv def set_cache_size(self, size): with self._cache_lock: self.__strong_cache_size = size while len(self.__strong_cache) > size: self.__strong_cache.popitem(last=False) def cache_clear(self): with self._cache_lock: self.__instances = weakref.WeakValueDictionary() self.__strong_cache.clear() @staticmethod def nocache(name=None): """A non-cached version of gettz""" tz = None if not name: try: name = os.environ["TZ"] except KeyError: pass if name is None or name in ("", ":"): for filepath in TZFILES: if not os.path.isabs(filepath): filename = filepath for path in _tzpath.TZPATH: filepath = os.path.join(path, filename) if _isfile(filepath): break else: continue if _isfile(filepath): try: tz = tzfile(filepath) break except (IOError, OSError, ValueError): pass else: tz = tzlocal() else: try: if name.startswith(":"): name = name[1:] except TypeError as e: if isinstance(name, bytes): new_msg = "gettz argument should be str, not bytes" six.raise_from(TypeError(new_msg), e) else: raise # A NUL byte can never be part of a key or a path, and # depending on the platform and Python version it raises # ValueError from os.path, winreg or open(), so reject it # up front rather than catching it in every branch. if "\x00" in name: return None if os.path.isabs(name): if _isfile(name): tz = tzfile(name) else: tz = None else: if _escapes_tzpath(name): _warn_tzpath_escape(name) for path in _tzpath.TZPATH: filepath = os.path.join(path, name) if not _isfile(filepath): filepath = filepath.replace(' ', '_') if not _isfile(filepath): continue try: tz = tzfile(filepath, key=name) break except (IOError, OSError, ValueError): # TODO: A file that exists but can't be read or # isn't a valid TZif file is silently skipped, # and the key is looked up in the next TZPATH # entry and then in tzdata. Consider warning # here, since this usually means the system time # zone data is broken. pass else: tz = None # As with the search path lookup above, also try # the name with spaces replaced by underscores. candidates = [name] if " " in name: candidates.append(name.replace(" ", "_")) for candidate in candidates: try: with _tzdata_impl._load_tzdata(candidate) as f: return tzfile(f, key=name) except ValueError: # TZFileNotFound is a ValueError, and so is # the error raised for files in tzdata that # are not TZif files (e.g. "zone.tab"), # which are skipped just as on TZPATH. pass if tzwin is not None: try: tz = tzwin(name) except (WindowsError, UnicodeEncodeError): # UnicodeEncodeError is for Python 2.7 compat tz = None if not tz: for c in name: # name is not a tzstr unless it has at least # one offset. For short values of "name", an # explicit for loop seems to be the fastest way # To determine if a string contains a digit if c in "0123456789": try: tz = tzstr(name) except ValueError: pass break else: if name in ("GMT", "UTC"): tz = UTC elif name in time.tzname: tz = tzlocal() return tz return GettzFunc() gettz = __get_gettz() del __get_gettz class DeprecatedTzKeyWarning(FutureWarning): """Warning raised when :func:`gettz` is given a key outside of TZPATH. Relative keys like ``"../../etc/localtime"`` resolve to files outside of every directory on :data:`TZPATH`. Support for these is deprecated, and a warnings filter turns this warning into an error by default. To keep the old behavior for now, filter it out, e.g.:: warnings.filterwarnings( "ignore", category=dateutil.tz.DeprecatedTzKeyWarning ) Absolute paths to TZif files are not affected. """ def _escapes_tzpath(name): # A relative key stays inside every TZPATH entry unless, once normalized # (which also turns os.altsep into os.sep), it starts by going up a # directory. return os.path.normpath(name).split(os.sep, 1)[0] == os.pardir def _warn_tzpath_escape(name): # As in dateutil.zoneinfo.rebuild, the filter is appended at call time, # so any filter the user has installed for this category wins. warnings.filterwarnings( "error", category=DeprecatedTzKeyWarning, append=True ) warnings.warn( "gettz(%r) refers to a file outside of TZPATH; support for keys " "like this is deprecated and will be removed in a future version. " "Use an absolute path instead." % (name,), DeprecatedTzKeyWarning, stacklevel=4, ) def available_iana_timezones(): """Returns a set containing all available IANA time zones keys. These are suitable for use with :func:`gettz`. This is essentially a direct port of :py:func:`zoneinfo.available_timezones`. The search includes time zones found on :data:`TZPATH` as well as any time zones provided by the `tzdata `_ package if it is installed. :return: Returns a mutable set containing strings of time zones. Each call will return a fresh set. .. caution:: This may attempt to open a large number of files, since the best way to determine if a given file on the time zone search path is to open it and check for the "magic string" at the beginning. .. note:: These values are not designed to be exposed to end-users; for user-facing elements, applications should use something like CLDR (the Unicode Common Locale Data Repository) to get more user-friendly strings. """ # Start with loading from the tzdata package if it exists: this has a # pre-assembled list of zones that only requires opening one file. try: valid_zones = set(_tzdata_impl._load_tzdata_keys()) except ImportError: valid_zones = set() def valid_key(fpath): try: with open(fpath, "rb") as f: return f.read(4) == b"TZif" except Exception: # pragma: nocover return False for tz_root in _tzpath.TZPATH: if not os.path.exists(tz_root): continue for root, dirnames, files in os.walk(tz_root): if root == tz_root: # right/ and posix/ are special directories and shouldn't be # included in the output of available zones if "right" in dirnames: dirnames.remove("right") if "posix" in dirnames: dirnames.remove("posix") for file in files: fpath = os.path.join(root, file) key = os.path.relpath(fpath, start=tz_root) if os.sep != "/": # pragma: nocover key = key.replace(os.sep, "/") if not key or key in valid_zones: continue if valid_key(fpath): valid_zones.add(key) if "posixrules" in valid_zones: # posixrules is a special symlink-only time zone where it exists, it # should not be included in the output valid_zones.remove("posixrules") if "localtime" in valid_zones: # localtime is a special symlink-only time zone where it exists, it # should not be included in the output valid_zones.remove("localtime") return valid_zones def datetime_exists(dt, tz=None): """ Given a datetime and a time zone, determine whether or not a given datetime would fall in a gap. :param dt: A :class:`datetime.datetime` (whose time zone will be ignored if ``tz`` is provided.) :param tz: A :class:`datetime.tzinfo` with support for the ``fold`` attribute. If ``None`` or not provided, the datetime's own time zone will be used. :return: Returns a boolean value whether or not the "wall time" exists in ``tz``. .. versionadded:: 2.7.0 """ if tz is None: if dt.tzinfo is None: raise ValueError('Datetime is naive and no time zone provided.') tz = dt.tzinfo dt = dt.replace(tzinfo=None) # This is essentially a test of whether or not the datetime can survive # a round trip to UTC. dt_rt = dt.replace(tzinfo=tz).astimezone(UTC).astimezone(tz) dt_rt = dt_rt.replace(tzinfo=None) return dt == dt_rt def datetime_ambiguous(dt, tz=None): """ Given a datetime and a time zone, determine whether or not a given datetime is ambiguous (i.e if there are two times differentiated only by their DST status). :param dt: A :class:`datetime.datetime` (whose time zone will be ignored if ``tz`` is provided.) :param tz: A :class:`datetime.tzinfo` with support for the ``fold`` attribute. If ``None`` or not provided, the datetime's own time zone will be used. :return: Returns a boolean value whether or not the "wall time" is ambiguous in ``tz``. .. versionadded:: 2.6.0 """ if tz is None: if dt.tzinfo is None: raise ValueError('Datetime is naive and no time zone provided.') tz = dt.tzinfo # If a time zone defines its own "is_ambiguous" function, we'll use that. is_ambiguous_fn = getattr(tz, 'is_ambiguous', None) if is_ambiguous_fn is not None: try: return tz.is_ambiguous(dt) except Exception: pass # If it doesn't come out and tell us it's ambiguous, we'll just check if # the fold attribute has any effect on this particular date and time. dt = dt.replace(tzinfo=tz) wall_0 = enfold(dt, fold=0) wall_1 = enfold(dt, fold=1) same_offset = wall_0.utcoffset() == wall_1.utcoffset() same_dst = wall_0.dst() == wall_1.dst() return not (same_offset and same_dst) def resolve_imaginary(dt): """ Given a datetime that may be imaginary, return an existing datetime. This function assumes that an imaginary datetime represents what the wall time would be in a zone had the offset transition not occurred, so it will always fall forward by the transition's change in offset. .. doctest:: >>> from dateutil import tz >>> from datetime import datetime >>> NYC = tz.gettz('America/New_York') >>> print(tz.resolve_imaginary(datetime(2017, 3, 12, 2, 30, tzinfo=NYC))) 2017-03-12 03:30:00-04:00 >>> KIR = tz.gettz('Pacific/Kiritimati') >>> print(tz.resolve_imaginary(datetime(1995, 1, 1, 12, 30, tzinfo=KIR))) 1995-01-02 12:30:00+14:00 As a note, :func:`datetime.astimezone` is guaranteed to produce a valid, existing datetime, so a round-trip to and from UTC is sufficient to get an extant datetime, however, this generally "falls back" to an earlier time rather than falling forward to the STD side (though no guarantees are made about this behavior). :param dt: A :class:`datetime.datetime` which may or may not exist. :return: Returns an existing :class:`datetime.datetime`. If ``dt`` was not imaginary, the datetime returned is guaranteed to be the same object passed to the function. .. versionadded:: 2.7.0 """ if dt.tzinfo is not None and not datetime_exists(dt): curr_offset = (dt + datetime.timedelta(hours=24)).utcoffset() old_offset = (dt - datetime.timedelta(hours=24)).utcoffset() dt += curr_offset - old_offset return dt def _datetime_to_timestamp(dt): """ Convert a :class:`datetime.datetime` object to an epoch timestamp in seconds since January 1, 1970, ignoring the time zone. """ return (dt.replace(tzinfo=None) - EPOCH).total_seconds() if sys.version_info >= (3, 6): def _get_supported_offset(second_offset): return second_offset else: def _get_supported_offset(second_offset): # For python pre-3.6, round to full-minutes if that's not the case. # Python's datetime doesn't accept sub-minute timezones. Check # http://python.org/sf/1447945 or https://bugs.python.org/issue5288 # for some information. old_offset = second_offset calculated_offset = 60 * ((second_offset + 30) // 60) return calculated_offset if sys.version_info < (3, 8): def _isfile(path): # bpo-33721: In Python 3.8 non-UTF8 paths return False rather than # raising an error. See https://bugs.python.org/issue33721 try: return os.path.isfile(path) except ValueError: return False else: _isfile = os.path.isfile try: # Python 3.7 feature from contextlib import nullcontext as _nullcontext except ImportError: class _nullcontext(object): """ Class for wrapping contexts so that they are passed through in a with statement. """ def __init__(self, context): self.context = context def __enter__(self): return self.context def __exit__(*args, **kwargs): pass # vim:ts=4:sw=4:et