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214 lines
7.5 KiB
214 lines
7.5 KiB
#
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# This file is part of pyasn1 software.
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#
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# Copyright (c) 2005-2019, Ilya Etingof <etingof@gmail.com>
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# License: http://snmplabs.com/pyasn1/license.html
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#
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from pyasn1 import debug
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from pyasn1 import error
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from pyasn1.type import base
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from pyasn1.type import char
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from pyasn1.type import tag
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from pyasn1.type import univ
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from pyasn1.type import useful
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__all__ = ['decode']
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LOG = debug.registerLoggee(__name__, flags=debug.DEBUG_DECODER)
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class AbstractScalarDecoder(object):
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def __call__(self, pyObject, asn1Spec, decodeFun=None, **options):
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return asn1Spec.clone(pyObject)
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class BitStringDecoder(AbstractScalarDecoder):
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def __call__(self, pyObject, asn1Spec, decodeFun=None, **options):
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return asn1Spec.clone(univ.BitString.fromBinaryString(pyObject))
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class SequenceOrSetDecoder(object):
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def __call__(self, pyObject, asn1Spec, decodeFun=None, **options):
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asn1Value = asn1Spec.clone()
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componentsTypes = asn1Spec.componentType
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for field in asn1Value:
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if field in pyObject:
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asn1Value[field] = decodeFun(pyObject[field], componentsTypes[field].asn1Object, **options)
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return asn1Value
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class SequenceOfOrSetOfDecoder(object):
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def __call__(self, pyObject, asn1Spec, decodeFun=None, **options):
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asn1Value = asn1Spec.clone()
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for pyValue in pyObject:
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asn1Value.append(decodeFun(pyValue, asn1Spec.componentType), **options)
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return asn1Value
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class ChoiceDecoder(object):
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def __call__(self, pyObject, asn1Spec, decodeFun=None, **options):
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asn1Value = asn1Spec.clone()
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componentsTypes = asn1Spec.componentType
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for field in pyObject:
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if field in componentsTypes:
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asn1Value[field] = decodeFun(pyObject[field], componentsTypes[field].asn1Object, **options)
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break
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return asn1Value
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tagMap = {
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univ.Integer.tagSet: AbstractScalarDecoder(),
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univ.Boolean.tagSet: AbstractScalarDecoder(),
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univ.BitString.tagSet: BitStringDecoder(),
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univ.OctetString.tagSet: AbstractScalarDecoder(),
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univ.Null.tagSet: AbstractScalarDecoder(),
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univ.ObjectIdentifier.tagSet: AbstractScalarDecoder(),
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univ.Enumerated.tagSet: AbstractScalarDecoder(),
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univ.Real.tagSet: AbstractScalarDecoder(),
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univ.Sequence.tagSet: SequenceOrSetDecoder(), # conflicts with SequenceOf
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univ.Set.tagSet: SequenceOrSetDecoder(), # conflicts with SetOf
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univ.Choice.tagSet: ChoiceDecoder(), # conflicts with Any
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# character string types
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char.UTF8String.tagSet: AbstractScalarDecoder(),
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char.NumericString.tagSet: AbstractScalarDecoder(),
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char.PrintableString.tagSet: AbstractScalarDecoder(),
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char.TeletexString.tagSet: AbstractScalarDecoder(),
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char.VideotexString.tagSet: AbstractScalarDecoder(),
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char.IA5String.tagSet: AbstractScalarDecoder(),
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char.GraphicString.tagSet: AbstractScalarDecoder(),
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char.VisibleString.tagSet: AbstractScalarDecoder(),
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char.GeneralString.tagSet: AbstractScalarDecoder(),
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char.UniversalString.tagSet: AbstractScalarDecoder(),
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char.BMPString.tagSet: AbstractScalarDecoder(),
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# useful types
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useful.ObjectDescriptor.tagSet: AbstractScalarDecoder(),
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useful.GeneralizedTime.tagSet: AbstractScalarDecoder(),
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useful.UTCTime.tagSet: AbstractScalarDecoder()
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}
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# Put in ambiguous & non-ambiguous types for faster codec lookup
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typeMap = {
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univ.Integer.typeId: AbstractScalarDecoder(),
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univ.Boolean.typeId: AbstractScalarDecoder(),
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univ.BitString.typeId: BitStringDecoder(),
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univ.OctetString.typeId: AbstractScalarDecoder(),
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univ.Null.typeId: AbstractScalarDecoder(),
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univ.ObjectIdentifier.typeId: AbstractScalarDecoder(),
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univ.Enumerated.typeId: AbstractScalarDecoder(),
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univ.Real.typeId: AbstractScalarDecoder(),
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# ambiguous base types
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univ.Set.typeId: SequenceOrSetDecoder(),
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univ.SetOf.typeId: SequenceOfOrSetOfDecoder(),
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univ.Sequence.typeId: SequenceOrSetDecoder(),
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univ.SequenceOf.typeId: SequenceOfOrSetOfDecoder(),
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univ.Choice.typeId: ChoiceDecoder(),
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univ.Any.typeId: AbstractScalarDecoder(),
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# character string types
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char.UTF8String.typeId: AbstractScalarDecoder(),
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char.NumericString.typeId: AbstractScalarDecoder(),
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char.PrintableString.typeId: AbstractScalarDecoder(),
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char.TeletexString.typeId: AbstractScalarDecoder(),
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char.VideotexString.typeId: AbstractScalarDecoder(),
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char.IA5String.typeId: AbstractScalarDecoder(),
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char.GraphicString.typeId: AbstractScalarDecoder(),
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char.VisibleString.typeId: AbstractScalarDecoder(),
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char.GeneralString.typeId: AbstractScalarDecoder(),
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char.UniversalString.typeId: AbstractScalarDecoder(),
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char.BMPString.typeId: AbstractScalarDecoder(),
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# useful types
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useful.ObjectDescriptor.typeId: AbstractScalarDecoder(),
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useful.GeneralizedTime.typeId: AbstractScalarDecoder(),
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useful.UTCTime.typeId: AbstractScalarDecoder()
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}
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class Decoder(object):
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# noinspection PyDefaultArgument
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def __init__(self, tagMap, typeMap):
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self.__tagMap = tagMap
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self.__typeMap = typeMap
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def __call__(self, pyObject, asn1Spec, **options):
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if LOG:
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debug.scope.push(type(pyObject).__name__)
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LOG('decoder called at scope %s, working with type %s' % (debug.scope, type(pyObject).__name__))
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if asn1Spec is None or not isinstance(asn1Spec, base.Asn1Item):
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raise error.PyAsn1Error('asn1Spec is not valid (should be an instance of an ASN.1 Item, not %s)' % asn1Spec.__class__.__name__)
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try:
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valueDecoder = self.__typeMap[asn1Spec.typeId]
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except KeyError:
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# use base type for codec lookup to recover untagged types
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baseTagSet = tag.TagSet(asn1Spec.tagSet.baseTag, asn1Spec.tagSet.baseTag)
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try:
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valueDecoder = self.__tagMap[baseTagSet]
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except KeyError:
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raise error.PyAsn1Error('Unknown ASN.1 tag %s' % asn1Spec.tagSet)
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if LOG:
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LOG('calling decoder %s on Python type %s <%s>' % (type(valueDecoder).__name__, type(pyObject).__name__, repr(pyObject)))
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value = valueDecoder(pyObject, asn1Spec, self, **options)
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if LOG:
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LOG('decoder %s produced ASN.1 type %s <%s>' % (type(valueDecoder).__name__, type(value).__name__, repr(value)))
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debug.scope.pop()
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return value
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#: Turns Python objects of built-in types into ASN.1 objects.
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#:
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#: Takes Python objects of built-in types and turns them into a tree of
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#: ASN.1 objects (e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative) which
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#: may be a scalar or an arbitrary nested structure.
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#:
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#: Parameters
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#: ----------
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#: pyObject: :py:class:`object`
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#: A scalar or nested Python objects
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#:
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#: Keyword Args
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#: ------------
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#: asn1Spec: any pyasn1 type object e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative
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#: A pyasn1 type object to act as a template guiding the decoder. It is required
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#: for successful interpretation of Python objects mapping into their ASN.1
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#: representations.
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#:
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#: Returns
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#: -------
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#: : :py:class:`~pyasn1.type.base.PyAsn1Item` derivative
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#: A scalar or constructed pyasn1 object
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#:
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#: Raises
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#: ------
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#: ~pyasn1.error.PyAsn1Error
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#: On decoding errors
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#:
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#: Examples
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#: --------
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#: Decode native Python object into ASN.1 objects with ASN.1 schema
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#:
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#: .. code-block:: pycon
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#:
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#: >>> seq = SequenceOf(componentType=Integer())
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#: >>> s, _ = decode([1, 2, 3], asn1Spec=seq)
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#: >>> str(s)
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#: SequenceOf:
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#: 1 2 3
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#:
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decode = Decoder(tagMap, typeMap)
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