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[EDIT] FILE: useful.py

#
# This file is part of pyasn1 software.
#
# Copyright (c) 2005-2020, Ilya Etingof <etingof@gmail.com>
# License: https://pyasn1.readthedocs.io/en/latest/license.html
#
import datetime

from pyasn1 import error
from pyasn1.type import char
from pyasn1.type import tag
from pyasn1.type import univ

__all__ = ['ObjectDescriptor', 'GeneralizedTime', 'UTCTime']

NoValue = univ.NoValue
noValue = univ.noValue

class ObjectDescriptor(char.GraphicString):
    __doc__ = char.GraphicString.__doc__

#: Default :py:class:`~pyasn1.type.tag.TagSet` object for |ASN.1| objects
    tagSet = char.GraphicString.tagSet.tagImplicitly(
        tag.Tag(tag.tagClassUniversal, tag.tagFormatSimple, 7)
    )

# Optimization for faster codec lookup
    typeId = char.GraphicString.getTypeId()

class TimeMixIn(object):

_yearsDigits = 4
    _hasSubsecond = False
    _optionalMinutes = False
    _shortTZ = False

class FixedOffset(datetime.tzinfo):
        """Fixed offset in minutes east from UTC."""

# defaulted arguments required
        # https: // docs.python.org / 2.3 / lib / datetime - tzinfo.html
        def __init__(self, offset=0, name='UTC'):
            self.__offset = datetime.timedelta(minutes=offset)
            self.__name = name

def utcoffset(self, dt):
            return self.__offset

def tzname(self, dt):
            return self.__name

def dst(self, dt):
            return datetime.timedelta(0)

UTC = FixedOffset()

@property
    def asDateTime(self):
        """Create :py:class:`datetime.datetime` object from a |ASN.1| object.

Returns
        -------
        :
            new instance of :py:class:`datetime.datetime` object
        """
        text = str(self)
        if text.endswith('Z'):
            tzinfo = TimeMixIn.UTC
            text = text[:-1]

elif '-' in text or '+' in text:
            if '+' in text:
                text, plusminus, tz = text.partition('+')
            else:
                text, plusminus, tz = text.partition('-')

if self._shortTZ and len(tz) == 2:
                tz += '00'

if len(tz) != 4:
                raise error.PyAsn1Error('malformed time zone offset %s' % tz)

try:
                minutes = int(tz[:2]) * 60 + int(tz[2:])
                if plusminus == '-':
                    minutes *= -1

except ValueError:
                raise error.PyAsn1Error('unknown time specification %s' % self)

tzinfo = TimeMixIn.FixedOffset(minutes, '?')

else:
            tzinfo = None

if '.' in text or ',' in text:
            if '.' in text:
                text, _, ms = text.partition('.')
            else:
                text, _, ms = text.partition(',')

try:
                ms = int(ms) * 1000

except ValueError:
                raise error.PyAsn1Error('bad sub-second time specification %s' % self)

else:
            ms = 0

if self._optionalMinutes and len(text) - self._yearsDigits == 6:
            text += '0000'
        elif len(text) - self._yearsDigits == 8:
            text += '00'

try:
            dt = datetime.datetime.strptime(text, self._yearsDigits == 4 and '%Y%m%d%H%M%S' or '%y%m%d%H%M%S')

except ValueError:
            raise error.PyAsn1Error('malformed datetime format %s' % self)

return dt.replace(microsecond=ms, tzinfo=tzinfo)

@classmethod
    def fromDateTime(cls, dt):
        """Create |ASN.1| object from a :py:class:`datetime.datetime` object.

Parameters
        ----------
        dt: :py:class:`datetime.datetime` object
            The `datetime.datetime` object to initialize the |ASN.1| object
            from

Returns
        -------
        :
            new instance of |ASN.1| value
        """
        text = dt.strftime(cls._yearsDigits == 4 and '%Y%m%d%H%M%S' or '%y%m%d%H%M%S')
        if cls._hasSubsecond:
            text += '.%d' % (dt.microsecond // 1000)

if dt.utcoffset():
            seconds = dt.utcoffset().seconds
            if seconds < 0:
                text += '-'
            else:
                text += '+'
            text += '%.2d%.2d' % (seconds // 3600, seconds % 3600)
        else:
            text += 'Z'

return cls(text)

class GeneralizedTime(char.VisibleString, TimeMixIn):
    __doc__ = char.VisibleString.__doc__

#: Default :py:class:`~pyasn1.type.tag.TagSet` object for |ASN.1| objects
    tagSet = char.VisibleString.tagSet.tagImplicitly(
        tag.Tag(tag.tagClassUniversal, tag.tagFormatSimple, 24)
    )

# Optimization for faster codec lookup
    typeId = char.VideotexString.getTypeId()

_yearsDigits = 4
    _hasSubsecond = True
    _optionalMinutes = True
    _shortTZ = True

class UTCTime(char.VisibleString, TimeMixIn):
    __doc__ = char.VisibleString.__doc__

#: Default :py:class:`~pyasn1.type.tag.TagSet` object for |ASN.1| objects
    tagSet = char.VisibleString.tagSet.tagImplicitly(
        tag.Tag(tag.tagClassUniversal, tag.tagFormatSimple, 23)
    )

# Optimization for faster codec lookup
    typeId = char.VideotexString.getTypeId()

_yearsDigits = 2
    _hasSubsecond = False
    _optionalMinutes = False
    _shortTZ = False

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