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  #   ˆl–ßi~”Š_)â€~ãmÜeõ1hßË„ì¸÷ÃÉ ?÷     '''Base classes and helpers for building zone specific tzinfo classes'''

from datetime import datetime, timedelta, tzinfo
from bisect import bisect_right
try:
    set
except NameError:
    from sets import Set as set

import pytz
from pytz.exceptions import AmbiguousTimeError, NonExistentTimeError

__all__ = []

_timedelta_cache = {}
def memorized_timedelta(seconds):
    '''Create only one instance of each distinct timedelta'''
    try:
        return _timedelta_cache[seconds]
    except KeyError:
        delta = timedelta(seconds=seconds)
        _timedelta_cache[seconds] = delta
        return delta

_epoch = datetime.utcfromtimestamp(0)
_datetime_cache = {0: _epoch}
def memorized_datetime(seconds):
    '''Create only one instance of each distinct datetime'''
    try:
        return _datetime_cache[seconds]
    except KeyError:
        # NB. We can't just do datetime.utcfromtimestamp(seconds) as this
        # fails with negative values under Windows (Bug #90096)
        dt = _epoch + timedelta(seconds=seconds)
        _datetime_cache[seconds] = dt
        return dt

_ttinfo_cache = {}
def memorized_ttinfo(*args):
    '''Create only one instance of each distinct tuple'''
    try:
        return _ttinfo_cache[args]
    except KeyError:
        ttinfo = (
                memorized_timedelta(args[0]),
                memorized_timedelta(args[1]),
                args[2]
                )
        _ttinfo_cache[args] = ttinfo
        return ttinfo

_notime = memorized_timedelta(0)

def _to_seconds(td):
    '''Convert a timedelta to seconds'''
    return td.seconds + td.days * 24 * 60 * 60


class BaseTzInfo(tzinfo):
    # Overridden in subclass
    _utcoffset = None
    _tzname = None
    zone = None

    def __str__(self):
        return self.zone


class StaticTzInfo(BaseTzInfo):
    '''A timezone that has a constant offset from UTC

    These timezones are rare, as most locations have changed their
    offset at some point in their history
    '''
    def fromutc(self, dt):
        '''See datetime.tzinfo.fromutc'''
        if dt.tzinfo is not None and dt.tzinfo is not self:
            raise ValueError('fromutc: dt.tzinfo is not self')
        return (dt + self._utcoffset).replace(tzinfo=self)

    def utcoffset(self, dt, is_dst=None):
        '''See datetime.tzinfo.utcoffset

        is_dst is ignored for StaticTzInfo, and exists only to
        retain compatibility with DstTzInfo.
        '''
        return self._utcoffset

    def dst(self, dt, is_dst=None):
        '''See datetime.tzinfo.dst

        is_dst is ignored for StaticTzInfo, and exists only to
        retain compatibility with DstTzInfo.
        '''
        return _notime

    def tzname(self, dt, is_dst=None):
        '''See datetime.tzinfo.tzname

        is_dst is ignored for StaticTzInfo, and exists only to
        retain compatibility with DstTzInfo.
        '''
        return self._tzname

    def localize(self, dt, is_dst=False):
        '''Convert naive time to local time'''
        if dt.tzinfo is not None:
            raise ValueError('Not naive datetime (tzinfo is already set)')
        return dt.replace(tzinfo=self)

    def normalize(self, dt, is_dst=False):
        '''Correct the timezone information on the given datetime.

        This is normally a no-op, as StaticTzInfo timezones never have
        ambiguous cases to correct:

        >>> from pytz import timezone
        >>> gmt = timezone('GMT')
        >>> isinstance(gmt, StaticTzInfo)
        True
        >>> dt = datetime(2011, 5, 8, 1, 2, 3, tzinfo=gmt)
        >>> gmt.normalize(dt) is dt
        True

        The supported method of converting between timezones is to use
        datetime.astimezone(). Currently normalize() also works:

        >>> la = timezone('America/Los_Angeles')
        >>> dt = la.localize(datetime(2011, 5, 7, 1, 2, 3))
        >>> fmt = '%Y-%m-%d %H:%M:%S %Z (%z)'
        >>> gmt.normalize(dt).strftime(fmt)
        '2011-05-07 08:02:03 GMT (+0000)'
        '''
        if dt.tzinfo is self: