codekingpro/portable-devtools

1'''2This module provides some datetime.tzinfo implementations.3 4All those classes are taken from the Python documentation.5'''6from datetime import timedelta, tzinfo7import time8 9ZERO = timedelta(0)10# constant for zero time offset.11 12 13class Utc(tzinfo):14    '''UTC15 16    Universal time coordinated time zone.17    '''18 19    def utcoffset(self, dt):20        '''21        Return offset from UTC in minutes east of UTC, which is ZERO for UTC.22        '''23        return ZERO24 25    def tzname(self, dt):26        '''27        Return the time zone name corresponding to the datetime object dt,28        as a string.29        '''30        return "UTC"31 32    def dst(self, dt):33        '''34        Return the daylight saving time (DST) adjustment, in minutes east35        of UTC.36        '''37        return ZERO38 39    def __reduce__(self):40        '''41        When unpickling a Utc object, return the default instance below, UTC.42        '''43        return _Utc, ()44 45 46UTC = Utc()47# the default instance for UTC.48 49 50def _Utc():51    '''52    Helper function for unpickling a Utc object.53    '''54    return UTC55 56 57class FixedOffset(tzinfo):58    '''59    A class building tzinfo objects for fixed-offset time zones.60 61    Note that FixedOffset(0, 0, "UTC") or FixedOffset() is a different way to62    build a UTC tzinfo object.63    '''64 65    def __init__(self, offset_hours=0, offset_minutes=0, name="UTC"):66        '''67        Initialise an instance with time offset and name.68        The time offset should be positive for time zones east of UTC69        and negate for time zones west of UTC.70        '''71        self.__offset = timedelta(hours=offset_hours, minutes=offset_minutes)72        self.__name = name73 74    def utcoffset(self, dt):75        '''76        Return offset from UTC in minutes of UTC.77        '''78        return self.__offset79 80    def tzname(self, dt):81        '''82        Return the time zone name corresponding to the datetime object dt, as a83        string.84        '''85        return self.__name86 87    def dst(self, dt):88        '''89        Return the daylight saving time (DST) adjustment, in minutes east of90        UTC.91        '''92        return ZERO93 94    def __repr__(self):95        '''96        Return nicely formatted repr string.97        '''98        return "<FixedOffset %r>" % self.__name99 100 101STDOFFSET = timedelta(seconds=-time.timezone)102# locale time zone offset103 104# calculate local daylight saving offset if any.105if time.daylight:106    DSTOFFSET = timedelta(seconds=-time.altzone)107else:108    DSTOFFSET = STDOFFSET109 110DSTDIFF = DSTOFFSET - STDOFFSET111# difference between local time zone and local DST time zone112 113 114class LocalTimezone(tzinfo):115    """116    A class capturing the platform's idea of local time.117    """118 119    def utcoffset(self, dt):120        '''121        Return offset from UTC in minutes of UTC.122        '''123        if self._isdst(dt):124            return DSTOFFSET125        else:126            return STDOFFSET127 128    def dst(self, dt):129        '''130        Return daylight saving offset.131        '''132        if self._isdst(dt):133            return DSTDIFF134        else:135            return ZERO136 137    def tzname(self, dt):138        '''139        Return the time zone name corresponding to the datetime object dt, as a140        string.141        '''142        return time.tzname[self._isdst(dt)]143 144    def _isdst(self, dt):145        '''146        Returns true if DST is active for given datetime object dt.147        '''148        tt = (dt.year, dt.month, dt.day,149              dt.hour, dt.minute, dt.second,150              dt.weekday(), 0, -1)151        stamp = time.mktime(tt)152        tt = time.localtime(stamp)153        return tt.tm_isdst > 0154 155 156# the default instance for local time zone.157LOCAL = LocalTimezone()158