python类tzinfo()的实例源码

def get_timezone(zone=None):
    """Looks up a timezone by name and returns it.  The timezone object
    returned comes from ``pytz`` and corresponds to the `tzinfo` interface and
    can be used with all of the functions of Babel that operate with dates.

    If a timezone is not known a :exc:`LookupError` is raised.  If `zone`
    is ``None`` a local zone object is returned.

    :param zone: the name of the timezone to look up.  If a timezone object
                 itself is passed in, mit's returned unchanged.
    """
    if zone is None:
        return LOCALTZ
    if not isinstance(zone, string_types):
        return zone
    try:
        return _pytz.timezone(zone)
    except _pytz.UnknownTimeZoneError:
        raise LookupError('Unknown timezone %s' % zone)

def make_aware(value, timezone=None, is_dst=None):
    """
    Makes a naive datetime.datetime in a given time zone aware.
    """
    if timezone is None:
        timezone = get_current_timezone()
    if hasattr(timezone, 'localize'):
        # This method is available for pytz time zones.
        return timezone.localize(value, is_dst=is_dst)
    else:
        # Check that we won't overwrite the timezone of an aware datetime.
        if is_aware(value):
            raise ValueError(
                "make_aware expects a naive datetime, got %s" % value)
        # This may be wrong around DST changes!
        return value.replace(tzinfo=timezone)

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 _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 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 _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 get_timezone(zone=None):
    """Looks up a timezone by name and returns it.  The timezone object
    returned comes from ``pytz`` and corresponds to the `tzinfo` interface and
    can be used with all of the functions of Babel that operate with dates.

    If a timezone is not known a :exc:`LookupError` is raised.  If `zone`
    is ``None`` a local zone object is returned.

    :param zone: the name of the timezone to look up.  If a timezone object
                 itself is passed in, mit's returned unchanged.
    """
    if zone is None:
        return LOCALTZ
    if not isinstance(zone, string_types):
        return zone
    try:
        return _pytz.timezone(zone)
    except _pytz.UnknownTimeZoneError:
        raise LookupError('Unknown timezone %s' % zone)

def get_timezone():
    """Returns the timezone that should be used for this request as
    `pytz.timezone` object.  This returns `None` if used outside of
    a request.
    """
    ctx = _request_ctx_stack.top
    tzinfo = getattr(ctx, 'babel_tzinfo', None)
    if tzinfo is None:
        babel = ctx.app.extensions['babel']
        if babel.timezone_selector_func is None:
            tzinfo = babel.default_timezone
        else:
            rv = babel.timezone_selector_func()
            if rv is None:
                tzinfo = babel.default_timezone
            else:
                if isinstance(rv, string_types):
                    tzinfo = timezone(rv)
                else:
                    tzinfo = rv
        ctx.babel_tzinfo = tzinfo
    return tzinfo

def __init__(self, weeks=0, days=0, hours=0, minutes=0, seconds=0, start_date=None,
                 end_date=None, timezone=None):
        self.interval = timedelta(weeks=weeks, days=days, hours=hours, minutes=minutes,
                                  seconds=seconds)
        self.interval_length = timedelta_seconds(self.interval)
        if self.interval_length == 0:
            self.interval = timedelta(seconds=1)
            self.interval_length = 1

        if timezone:
            self.timezone = astimezone(timezone)
        elif start_date and start_date.tzinfo:
            self.timezone = start_date.tzinfo
        elif end_date and end_date.tzinfo:
            self.timezone = end_date.tzinfo
        else:
            self.timezone = get_localzone()

        start_date = start_date or (datetime.now(self.timezone) + self.interval)
        self.start_date = convert_to_datetime(start_date, self.timezone, 'start_date')
        self.end_date = convert_to_datetime(end_date, self.timezone, 'end_date')

def astimezone(obj):
    """
    Interprets an object as a timezone.

    :rtype: tzinfo

    """
    if isinstance(obj, six.string_types):
        return timezone(obj)
    if isinstance(obj, tzinfo):
        if not hasattr(obj, 'localize') or not hasattr(obj, 'normalize'):
            raise TypeError('Only timezones from the pytz library are supported')
        if obj.zone == 'local':
            raise ValueError(
                'Unable to determine the name of the local timezone -- you must explicitly '
                'specify the name of the local timezone. Please refrain from using timezones like '
                'EST to prevent problems with daylight saving time. Instead, use a locale based '
                'timezone name (such as Europe/Helsinki).')
        return obj
    if obj is not None:
        raise TypeError('Expected tzinfo, got %s instead' % obj.__class__.__name__)

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 _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 __init__(self, value, locale):
        assert isinstance(value, (date, datetime, time))
        if isinstance(value, (datetime, time)) and value.tzinfo is None:
            value = value.replace(tzinfo=UTC)
        self.value = value
        self.locale = Locale.parse(locale)

def __init__(self):
        self.STDOFFSET = timedelta(seconds=-_time.timezone)
        if _time.daylight:
            self.DSTOFFSET = timedelta(seconds=-_time.altzone)
        else:
            self.DSTOFFSET = self.STDOFFSET
        self.DSTDIFF = self.DSTOFFSET - self.STDOFFSET
        tzinfo.__init__(self)

def get_fixed_timezone(offset):
    """
    Returns a tzinfo instance with a fixed offset from UTC.
    """
    if isinstance(offset, timedelta):
        offset = offset.seconds // 60
    sign = '-' if offset < 0 else '+'
    hhmm = '%02d%02d' % divmod(abs(offset), 60)
    name = sign + hhmm
    return FixedOffset(offset, name)


# In order to avoid accessing settings at compile time,
# wrap the logic in a function and cache the result.

def get_default_timezone():
    """
    Returns the default time zone as a tzinfo instance.

    This is the time zone defined by settings.TIME_ZONE.
    """
    if isinstance(settings.TIME_ZONE, six.string_types) and pytz is not None:
        return pytz.timezone(settings.TIME_ZONE)
    else:
        # This relies on os.environ['TZ'] being set to settings.TIME_ZONE.
        return LocalTimezone()


# This function exists for consistency with get_current_timezone_name

def get_current_timezone():
    """
    Returns the currently active time zone as a tzinfo instance.
    """
    return getattr(_active, "value", get_default_timezone())