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Diffstat (limited to 'python/dateutil/tz/_common.py')
| -rw-r--r-- | python/dateutil/tz/_common.py | 394 |
1 files changed, 0 insertions, 394 deletions
diff --git a/python/dateutil/tz/_common.py b/python/dateutil/tz/_common.py deleted file mode 100644 index f1cf2af..0000000 --- a/python/dateutil/tz/_common.py +++ /dev/null @@ -1,394 +0,0 @@ -from six import PY3 - -from functools import wraps - -from datetime import datetime, timedelta, tzinfo - - -ZERO = timedelta(0) - -__all__ = ['tzname_in_python2', 'enfold'] - - -def tzname_in_python2(namefunc): - """Change unicode output into bytestrings in Python 2 - - tzname() API changed in Python 3. It used to return bytes, but was changed - to unicode strings - """ - def adjust_encoding(*args, **kwargs): - name = namefunc(*args, **kwargs) - if name is not None and not PY3: - name = name.encode() - - return name - - return adjust_encoding - - -# The following is adapted from Alexander Belopolsky's tz library -# https://github.com/abalkin/tz -if hasattr(datetime, 'fold'): - # This is the pre-python 3.6 fold situation - def enfold(dt, fold=1): - """ - Provides a unified interface for assigning the ``fold`` attribute to - datetimes both before and after the implementation of PEP-495. - - :param fold: - The value for the ``fold`` attribute in the returned datetime. This - should be either 0 or 1. - - :return: - Returns an object for which ``getattr(dt, 'fold', 0)`` returns - ``fold`` for all versions of Python. In versions prior to - Python 3.6, this is a ``_DatetimeWithFold`` object, which is a - subclass of :py:class:`datetime.datetime` with the ``fold`` - attribute added, if ``fold`` is 1. - - .. versionadded:: 2.6.0 - """ - return dt.replace(fold=fold) - -else: - class _DatetimeWithFold(datetime): - """ - This is a class designed to provide a PEP 495-compliant interface for - Python versions before 3.6. It is used only for dates in a fold, so - the ``fold`` attribute is fixed at ``1``. - - .. versionadded:: 2.6.0 - """ - __slots__ = () - - @property - def fold(self): - return 1 - - def enfold(dt, fold=1): - """ - Provides a unified interface for assigning the ``fold`` attribute to - datetimes both before and after the implementation of PEP-495. - - :param fold: - The value for the ``fold`` attribute in the returned datetime. This - should be either 0 or 1. - - :return: - Returns an object for which ``getattr(dt, 'fold', 0)`` returns - ``fold`` for all versions of Python. In versions prior to - Python 3.6, this is a ``_DatetimeWithFold`` object, which is a - subclass of :py:class:`datetime.datetime` with the ``fold`` - attribute added, if ``fold`` is 1. - - .. versionadded:: 2.6.0 - """ - if getattr(dt, 'fold', 0) == fold: - return dt - - args = dt.timetuple()[:6] - args += (dt.microsecond, dt.tzinfo) - - if fold: - return _DatetimeWithFold(*args) - else: - return datetime(*args) - - -def _validate_fromutc_inputs(f): - """ - The CPython version of ``fromutc`` checks that the input is a ``datetime`` - object and that ``self`` is attached as its ``tzinfo``. - """ - @wraps(f) - def fromutc(self, dt): - if not isinstance(dt, datetime): - raise TypeError("fromutc() requires a datetime argument") - if dt.tzinfo is not self: - raise ValueError("dt.tzinfo is not self") - - return f(self, dt) - - return fromutc - - -class _tzinfo(tzinfo): - """ - Base class for all ``dateutil`` ``tzinfo`` objects. - """ - - 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 - """ - - dt = dt.replace(tzinfo=self) - - wall_0 = enfold(dt, fold=0) - wall_1 = enfold(dt, fold=1) - - same_offset = wall_0.utcoffset() == wall_1.utcoffset() - same_dt = wall_0.replace(tzinfo=None) == wall_1.replace(tzinfo=None) - - return same_dt and not same_offset - - def _fold_status(self, dt_utc, dt_wall): - """ - Determine the fold status of a "wall" datetime, given a representation - of the same datetime as a (naive) UTC datetime. This is calculated based - on the assumption that ``dt.utcoffset() - dt.dst()`` is constant for all - datetimes, and that this offset is the actual number of hours separating - ``dt_utc`` and ``dt_wall``. - - :param dt_utc: - Representation of the datetime as UTC - - :param dt_wall: - Representation of the datetime as "wall time". This parameter must - either have a `fold` attribute or have a fold-naive - :class:`datetime.tzinfo` attached, otherwise the calculation may - fail. - """ - if self.is_ambiguous(dt_wall): - delta_wall = dt_wall - dt_utc - _fold = int(delta_wall == (dt_utc.utcoffset() - dt_utc.dst())) - else: - _fold = 0 - - return _fold - - def _fold(self, dt): - return getattr(dt, 'fold', 0) - - def _fromutc(self, dt): - """ - Given a timezone-aware datetime in a given timezone, calculates a - timezone-aware datetime in a new timezone. - - Since this is the one time that we *know* we have an unambiguous - datetime object, we take this opportunity to determine whether the - datetime is ambiguous and in a "fold" state (e.g. if it's the first - occurence, chronologically, of the ambiguous datetime). - - :param dt: - A timezone-aware :class:`datetime.datetime` object. - """ - - # Re-implement the algorithm from Python's datetime.py - dtoff = dt.utcoffset() - if dtoff is None: - raise ValueError("fromutc() requires a non-None utcoffset() " - "result") - - # The original datetime.py code assumes that `dst()` defaults to - # zero during ambiguous times. PEP 495 inverts this presumption, so - # for pre-PEP 495 versions of python, we need to tweak the algorithm. - dtdst = dt.dst() - if dtdst is None: - raise ValueError("fromutc() requires a non-None dst() result") - delta = dtoff - dtdst - - dt += delta - # Set fold=1 so we can default to being in the fold for - # ambiguous dates. - dtdst = enfold(dt, fold=1).dst() - if dtdst is None: - raise ValueError("fromutc(): dt.dst gave inconsistent " - "results; cannot convert") - return dt + dtdst - - @_validate_fromutc_inputs - def fromutc(self, dt): - """ - Given a timezone-aware datetime in a given timezone, calculates a - timezone-aware datetime in a new timezone. - - Since this is the one time that we *know* we have an unambiguous - datetime object, we take this opportunity to determine whether the - datetime is ambiguous and in a "fold" state (e.g. if it's the first - occurance, chronologically, of the ambiguous datetime). - - :param dt: - A timezone-aware :class:`datetime.datetime` object. - """ - dt_wall = self._fromutc(dt) - - # Calculate the fold status given the two datetimes. - _fold = self._fold_status(dt, dt_wall) - - # Set the default fold value for ambiguous dates - return enfold(dt_wall, fold=_fold) - - -class tzrangebase(_tzinfo): - """ - This is an abstract base class for time zones represented by an annual - transition into and out of DST. Child classes should implement the following - methods: - - * ``__init__(self, *args, **kwargs)`` - * ``transitions(self, year)`` - this is expected to return a tuple of - datetimes representing the DST on and off transitions in standard - time. - - A fully initialized ``tzrangebase`` subclass should also provide the - following attributes: - * ``hasdst``: Boolean whether or not the zone uses DST. - * ``_dst_offset`` / ``_std_offset``: :class:`datetime.timedelta` objects - representing the respective UTC offsets. - * ``_dst_abbr`` / ``_std_abbr``: Strings representing the timezone short - abbreviations in DST and STD, respectively. - * ``_hasdst``: Whether or not the zone has DST. - - .. versionadded:: 2.6.0 - """ - def __init__(self): - raise NotImplementedError('tzrangebase is an abstract base class') - - def utcoffset(self, dt): - isdst = self._isdst(dt) - - if isdst is None: - return None - elif isdst: - return self._dst_offset - else: - return self._std_offset - - def dst(self, dt): - isdst = self._isdst(dt) - - if isdst is None: - return None - elif isdst: - return self._dst_base_offset - else: - return ZERO - - @tzname_in_python2 - def tzname(self, dt): - if self._isdst(dt): - return self._dst_abbr - else: - return self._std_abbr - - def fromutc(self, dt): - """ Given a datetime in UTC, return local time """ - if not isinstance(dt, datetime): - raise TypeError("fromutc() requires a datetime argument") - - if dt.tzinfo is not self: - raise ValueError("dt.tzinfo is not self") - - # Get transitions - if there are none, fixed offset - transitions = self.transitions(dt.year) - if transitions is None: - return dt + self.utcoffset(dt) - - # Get the transition times in UTC - dston, dstoff = transitions - - dston -= self._std_offset - dstoff -= self._std_offset - - utc_transitions = (dston, dstoff) - dt_utc = dt.replace(tzinfo=None) - - isdst = self._naive_isdst(dt_utc, utc_transitions) - - if isdst: - dt_wall = dt + self._dst_offset - else: - dt_wall = dt + self._std_offset - - _fold = int(not isdst and self.is_ambiguous(dt_wall)) - - return enfold(dt_wall, fold=_fold) - - 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 - """ - if not self.hasdst: - return False - - start, end = self.transitions(dt.year) - - dt = dt.replace(tzinfo=None) - return (end <= dt < end + self._dst_base_offset) - - def _isdst(self, dt): - if not self.hasdst: - return False - elif dt is None: - return None - - transitions = self.transitions(dt.year) - - if transitions is None: - return False - - dt = dt.replace(tzinfo=None) - - isdst = self._naive_isdst(dt, transitions) - - # Handle ambiguous dates - if not isdst and self.is_ambiguous(dt): - return not self._fold(dt) - else: - return isdst - - def _naive_isdst(self, dt, transitions): - dston, dstoff = transitions - - dt = dt.replace(tzinfo=None) - - if dston < dstoff: - isdst = dston <= dt < dstoff - else: - isdst = not dstoff <= dt < dston - - return isdst - - @property - def _dst_base_offset(self): - return self._dst_offset - self._std_offset - - __hash__ = None - - def __ne__(self, other): - return not (self == other) - - def __repr__(self): - return "%s(...)" % self.__class__.__name__ - - __reduce__ = object.__reduce__ - - -def _total_seconds(td): - # Python 2.6 doesn't have a total_seconds() method on timedelta objects - return ((td.seconds + td.days * 86400) * 1000000 + - td.microseconds) // 1000000 - - -_total_seconds = getattr(timedelta, 'total_seconds', _total_seconds) |