Class Null

pager_lib/pyasn1/type/univ.py:971–1020

Create |ASN.1| schema or value object. |ASN.1| class is based on :class:`~pyasn1.type.base.SimpleAsn1Type`, its objects are immutable and duck-type Python :class:`str` objects (always empty). Keyword Args ------------ value: :class:`str` or |ASN.1| object Python emp

class Null(OctetString):
    """Create |ASN.1| schema or value object.

    |ASN.1| class is based on :class:`~pyasn1.type.base.SimpleAsn1Type`, its
    objects are immutable and duck-type Python :class:`str` objects
    (always empty).

    Keyword Args
    ------------
    value: :class:`str` or |ASN.1| object
        Python empty :class:`str` literal or any object that evaluates to :obj:`False`
        If `value` is not given, schema object will be created.

    tagSet: :py:class:`~pyasn1.type.tag.TagSet`
        Object representing non-default ASN.1 tag(s)

    Raises
    ------
    ~pyasn1.error.ValueConstraintError, ~pyasn1.error.PyAsn1Error
        On constraint violation or bad initializer.

    Examples
    --------
    .. code-block:: python

        class Ack(Null):
            '''
            ASN.1 specification:

            Ack ::= NULL
            '''
        ack = Ack('')
    """

    #: Set (on class, not on instance) or return a
    #: :py:class:`~pyasn1.type.tag.TagSet` object representing ASN.1 tag(s)
    #: associated with |ASN.1| type.
    tagSet = tag.initTagSet(
        tag.Tag(tag.tagClassUniversal, tag.tagFormatSimple, 0x05)
    )
    subtypeSpec = OctetString.subtypeSpec + constraint.SingleValueConstraint(b'')

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

    def prettyIn(self, value):
        if value:
            return value

        return b''


class ObjectIdentifier(base.SimpleAsn1Type):