File: //lib/python3.6/site-packages/pyasn1/type/base.py
#
# This file is part of pyasn1 software.
#
# Copyright (c) 2005-2017, Ilya Etingof <etingof@gmail.com>
# License: http://pyasn1.sf.net/license.html
#
import sys
from pyasn1.type import constraint, tagmap, tag
from pyasn1.compat import calling
from pyasn1 import error
__all__ = ['Asn1Item', 'Asn1ItemBase', 'AbstractSimpleAsn1Item', 'AbstractConstructedAsn1Item']
class Asn1Item(object):
@classmethod
def getTypeId(cls, increment=1):
try:
Asn1Item._typeCounter += increment
except AttributeError:
Asn1Item._typeCounter = increment
return Asn1Item._typeCounter
class Asn1ItemBase(Asn1Item):
#: Set or return a :py:class:`~pyasn1.type.tag.TagSet` object representing
#: ASN.1 tag(s) associated with |ASN.1| type.
tagSet = tag.TagSet()
#: Default :py:class:`~pyasn1.type.constraint.ConstraintsIntersection`
#: object imposing constraints on initialization values.
subtypeSpec = constraint.ConstraintsIntersection()
# Disambiguation ASN.1 types identification
typeId = None
def __init__(self, **kwargs):
readOnly = {
'tagSet': self.tagSet,
'subtypeSpec': self.subtypeSpec
}
readOnly.update(kwargs)
self.__dict__.update(readOnly)
self._readOnly = readOnly
def __setattr__(self, name, value):
if name[0] != '_' and name in self._readOnly:
raise error.PyAsn1Error('read-only instance attribute "%s"' % name)
self.__dict__[name] = value
@property
def readOnly(self):
return self._readOnly
@property
def effectiveTagSet(self):
"""For |ASN.1| type is equivalent to *tagSet*
"""
return self.tagSet # used by untagged types
@property
def tagMap(self):
"""Return a :class:`~pyasn1.type.tagmap.TagMap` object mapping ASN.1 tags to ASN.1 objects within callee object.
"""
return tagmap.TagMap({self.tagSet: self})
def isSameTypeWith(self, other, matchTags=True, matchConstraints=True):
"""Examine |ASN.1| type for equality with other ASN.1 type.
ASN.1 tags (:py:mod:`~pyasn1.type.tag`) and constraints
(:py:mod:`~pyasn1.type.constraint`) are examined when carrying
out ASN.1 types comparison.
No Python inheritance relationship between PyASN1 objects is considered.
Parameters
----------
other: a pyasn1 type object
Class instance representing ASN.1 type.
Returns
-------
: :class:`bool`
:class:`True` if *other* is |ASN.1| type,
:class:`False` otherwise.
"""
return (self is other or
(not matchTags or self.tagSet == other.tagSet) and
(not matchConstraints or self.subtypeSpec == other.subtypeSpec))
def isSuperTypeOf(self, other, matchTags=True, matchConstraints=True):
"""Examine |ASN.1| type for subtype relationship with other ASN.1 type.
ASN.1 tags (:py:mod:`~pyasn1.type.tag`) and constraints
(:py:mod:`~pyasn1.type.constraint`) are examined when carrying
out ASN.1 types comparison.
No Python inheritance relationship between PyASN1 objects is considered.
Parameters
----------
other: a pyasn1 type object
Class instance representing ASN.1 type.
Returns
-------
: :class:`bool`
:class:`True` if *other* is a subtype of |ASN.1| type,
:class:`False` otherwise.
"""
return (not matchTags or
(self.tagSet.isSuperTagSetOf(other.tagSet)) and
(not matchConstraints or self.subtypeSpec.isSuperTypeOf(other.subtypeSpec)))
@staticmethod
def isNoValue(*values):
for value in values:
if value is not None and value is not noValue:
return False
return True
# backward compatibility
def getTagSet(self):
return self.tagSet
def getEffectiveTagSet(self):
return self.effectiveTagSet
def getTagMap(self):
return self.tagMap
def getSubtypeSpec(self):
return self.subtypeSpec
def hasValue(self):
return self.isValue
class NoValue(object):
"""Create a singleton instance of NoValue class.
NoValue object can be used as an initializer on PyASN1 type class
instantiation to represent ASN.1 type rather than ASN.1 data value.
No operations other than type comparison can be performed on
a PyASN1 type object.
"""
skipMethods = ('__getattribute__', '__getattr__', '__setattr__', '__delattr__',
'__class__', '__init__', '__del__', '__new__', '__repr__',
'__qualname__', '__objclass__', 'im_class', '__sizeof__')
_instance = None
def __new__(cls):
if cls._instance is None:
def getPlug(name):
def plug(self, *args, **kw):
raise error.PyAsn1Error('Uninitialized ASN.1 value ("%s" attribute looked up)' % name)
return plug
op_names = [name
for typ in (str, int, list, dict)
for name in dir(typ)
if (name not in cls.skipMethods and
name.startswith('__') and
name.endswith('__') and
calling.callable(getattr(typ, name)))]
for name in set(op_names):
setattr(cls, name, getPlug(name))
cls._instance = object.__new__(cls)
return cls._instance
def __getattr__(self, attr):
if attr in self.skipMethods:
raise AttributeError('attribute %s not present' % attr)
raise error.PyAsn1Error('No value for "%s"' % attr)
def __repr__(self):
return '%s()' % self.__class__.__name__
noValue = NoValue()
# Base class for "simple" ASN.1 objects. These are immutable.
class AbstractSimpleAsn1Item(Asn1ItemBase):
#: Default payload value
defaultValue = noValue
def __init__(self, value=noValue, **kwargs):
Asn1ItemBase.__init__(self, **kwargs)
if value is noValue or value is None:
value = self.defaultValue
else:
value = self.prettyIn(value)
try:
self.subtypeSpec(value)
except error.PyAsn1Error:
exType, exValue, exTb = sys.exc_info()
raise exType('%s at %s' % (exValue, self.__class__.__name__))
self._value = value
def __repr__(self):
representation = []
if self._value is not self.defaultValue:
representation.append(self.prettyOut(self._value))
if self.tagSet is not self.__class__.tagSet:
representation.append('tagSet=%r' % (self.tagSet,))
if self.subtypeSpec is not self.__class__.subtypeSpec:
representation.append('subtypeSpec=%r' % (self.subtypeSpec,))
return '%s(%s)' % (self.__class__.__name__, ', '.join(representation))
def __str__(self):
return str(self._value)
def __eq__(self, other):
return self is other and True or self._value == other
def __ne__(self, other):
return self._value != other
def __lt__(self, other):
return self._value < other
def __le__(self, other):
return self._value <= other
def __gt__(self, other):
return self._value > other
def __ge__(self, other):
return self._value >= other
if sys.version_info[0] <= 2:
def __nonzero__(self):
return self._value and True or False
else:
def __bool__(self):
return self._value and True or False
def __hash__(self):
return hash(self._value)
@property
def isValue(self):
"""Indicate if |ASN.1| object represents ASN.1 type or ASN.1 value.
In other words, if *isValue* is `True`, then the ASN.1 object is
initialized.
Returns
-------
: :class:`bool`
:class:`True` if object represents ASN.1 value and type,
:class:`False` if object represents just ASN.1 type.
Note
----
There is an important distinction between PyASN1 type and value objects.
The PyASN1 type objects can only participate in ASN.1 type
operations (subtyping, comparison etc) and serve as a
blueprint for serialization codecs to resolve ambiguous types.
The PyASN1 value objects can additionally participate in most
of built-in Python operations.
"""
return self._value is not noValue
def clone(self, value=noValue, **kwargs):
"""Create a copy of a |ASN.1| type or object.
Any parameters to the *clone()* method will replace corresponding
properties of the |ASN.1| object.
Parameters
----------
value: :class:`tuple`, :class:`str` or |ASN.1| object
Initialization value to pass to new ASN.1 object instead of
inheriting one from the caller.
tagSet: :py:class:`~pyasn1.type.tag.TagSet`
Object representing ASN.1 tag(s) to use in new object instead of inheriting from the caller
subtypeSpec: :py:class:`~pyasn1.type.constraint.ConstraintsIntersection`
Object representing ASN.1 subtype constraint(s) to use in new object instead of inheriting from the caller
Returns
-------
:
new instance of |ASN.1| type/value
"""
if value is noValue or value is None:
if not kwargs:
return self
value = self._value
initilaizers = self.readOnly.copy()
initilaizers.update(kwargs)
return self.__class__(value, **initilaizers)
def subtype(self, value=noValue, **kwargs):
"""Create a copy of a |ASN.1| type or object.
Any parameters to the *subtype()* method will be added to the corresponding
properties of the |ASN.1| object.
Parameters
----------
value: :class:`tuple`, :class:`str` or |ASN.1| object
Initialization value to pass to new ASN.1 object instead of
inheriting one from the caller.
implicitTag: :py:class:`~pyasn1.type.tag.Tag`
Implicitly apply given ASN.1 tag object to caller's
:py:class:`~pyasn1.type.tag.TagSet`, then use the result as
new object's ASN.1 tag(s).
explicitTag: :py:class:`~pyasn1.type.tag.Tag`
Explicitly apply given ASN.1 tag object to caller's
:py:class:`~pyasn1.type.tag.TagSet`, then use the result as
new object's ASN.1 tag(s).
subtypeSpec: :py:class:`~pyasn1.type.constraint.ConstraintsIntersection`
Add ASN.1 constraints object to one of the caller, then
use the result as new object's ASN.1 constraints.
Returns
-------
:
new instance of |ASN.1| type/value
"""
if value is noValue or value is None:
if not kwargs:
return self
value = self._value
initializers = self.readOnly.copy()
implicitTag = kwargs.pop('implicitTag', None)
if implicitTag is not None:
initializers['tagSet'] = self.tagSet.tagImplicitly(implicitTag)
explicitTag = kwargs.pop('explicitTag', None)
if explicitTag is not None:
initializers['tagSet'] = self.tagSet.tagExplicitly(explicitTag)
for arg, option in kwargs.items():
initializers[arg] += option
return self.__class__(value, **initializers)
def prettyIn(self, value):
return value
def prettyOut(self, value):
return str(value)
def prettyPrint(self, scope=0):
"""Provide human-friendly printable object representation.
Returns
-------
: :class:`str`
human-friendly type and/or value representation.
"""
if self.isValue:
return self.prettyOut(self._value)
else:
return '<no value>'
# XXX Compatibility stub
def prettyPrinter(self, scope=0):
return self.prettyPrint(scope)
# noinspection PyUnusedLocal
def prettyPrintType(self, scope=0):
return '%s -> %s' % (self.tagSet, self.__class__.__name__)
#
# Constructed types:
# * There are five of them: Sequence, SequenceOf/SetOf, Set and Choice
# * ASN1 types and values are represened by Python class instances
# * Value initialization is made for defaulted components only
# * Primary method of component addressing is by-position. Data model for base
# type is Python sequence. Additional type-specific addressing methods
# may be implemented for particular types.
# * SequenceOf and SetOf types do not implement any additional methods
# * Sequence, Set and Choice types also implement by-identifier addressing
# * Sequence, Set and Choice types also implement by-asn1-type (tag) addressing
# * Sequence and Set types may include optional and defaulted
# components
# * Constructed types hold a reference to component types used for value
# verification and ordering.
# * Component type is a scalar type for SequenceOf/SetOf types and a list
# of types for Sequence/Set/Choice.
#
def setupComponent():
"""Returns a sentinel value.
Indicates to a constructed type to set up its inner component so that it
can be referred to. This is useful in situation when you want to populate
descendants of a constructed type what requires being able to refer to
their parent types along the way.
Example
-------
>>> constructed['record'] = setupComponent()
>>> constructed['record']['scalar'] = 42
"""
return noValue
class AbstractConstructedAsn1Item(Asn1ItemBase):
#: If `True`, requires exact component type matching,
#: otherwise subtype relation is only enforced
strictConstraints = False
componentType = None
sizeSpec = None
def __init__(self, **kwargs):
readOnly = {
'componentType': self.componentType,
'sizeSpec': self.sizeSpec
}
readOnly.update(kwargs)
Asn1ItemBase.__init__(self, **readOnly)
self._componentValues = []
def __repr__(self):
representation = []
if self.componentType is not self.__class__.componentType:
representation.append('componentType=%r' % (self.componentType,))
if self.tagSet is not self.__class__.tagSet:
representation.append('tagSet=%r' % (self.tagSet,))
if self.subtypeSpec is not self.__class__.subtypeSpec:
representation.append('subtypeSpec=%r' % (self.subtypeSpec,))
representation = '%s(%s)' % (self.__class__.__name__, ', '.join(representation))
if self._componentValues:
for idx, component in enumerate(self._componentValues):
if component is None or component is noValue:
continue
representation += '.setComponentByPosition(%d, %s)' % (idx, repr(component))
return representation
def __eq__(self, other):
return self is other and True or self._componentValues == other
def __ne__(self, other):
return self._componentValues != other
def __lt__(self, other):
return self._componentValues < other
def __le__(self, other):
return self._componentValues <= other
def __gt__(self, other):
return self._componentValues > other
def __ge__(self, other):
return self._componentValues >= other
if sys.version_info[0] <= 2:
def __nonzero__(self):
return self._componentValues and True or False
else:
def __bool__(self):
return self._componentValues and True or False
def _cloneComponentValues(self, myClone, cloneValueFlag):
pass
def clone(self, **kwargs):
"""Create a copy of a |ASN.1| type or object.
Any parameters to the *clone()* method will replace corresponding
properties of the |ASN.1| object.
Parameters
----------
tagSet: :py:class:`~pyasn1.type.tag.TagSet`
Object representing non-default ASN.1 tag(s)
subtypeSpec: :py:class:`~pyasn1.type.constraint.ConstraintsIntersection`
Object representing non-default ASN.1 subtype constraint(s)
sizeSpec: :py:class:`~pyasn1.type.constraint.ConstraintsIntersection`
Object representing non-default ASN.1 size constraint(s)
Returns
-------
:
new instance of |ASN.1| type/value
"""
cloneValueFlag = kwargs.pop('cloneValueFlag', False)
initilaizers = self.readOnly.copy()
initilaizers.update(kwargs)
clone = self.__class__(**initilaizers)
if cloneValueFlag:
self._cloneComponentValues(clone, cloneValueFlag)
return clone
def subtype(self, **kwargs):
"""Create a copy of a |ASN.1| type or object.
Any parameters to the *subtype()* method will be added to the corresponding
properties of the |ASN.1| object.
Parameters
----------
tagSet: :py:class:`~pyasn1.type.tag.TagSet`
Object representing non-default ASN.1 tag(s)
subtypeSpec: :py:class:`~pyasn1.type.constraint.ConstraintsIntersection`
Object representing non-default ASN.1 subtype constraint(s)
sizeSpec: :py:class:`~pyasn1.type.constraint.ConstraintsIntersection`
Object representing non-default ASN.1 size constraint(s)
Returns
-------
:
new instance of |ASN.1| type/value
"""
initializers = self.readOnly.copy()
cloneValueFlag = kwargs.pop('cloneValueFlag', False)
implicitTag = kwargs.pop('implicitTag', None)
if implicitTag is not None:
initializers['tagSet'] = self.tagSet.tagImplicitly(implicitTag)
explicitTag = kwargs.pop('explicitTag', None)
if explicitTag is not None:
initializers['tagSet'] = self.tagSet.tagExplicitly(explicitTag)
for arg, option in kwargs.items():
initializers[arg] += option
clone = self.__class__(**initializers)
if cloneValueFlag:
self._cloneComponentValues(clone, cloneValueFlag)
return clone
def verifySizeSpec(self):
self.sizeSpec(self)
def getComponentByPosition(self, idx):
raise error.PyAsn1Error('Method not implemented')
def setComponentByPosition(self, idx, value, verifyConstraints=True):
raise error.PyAsn1Error('Method not implemented')
def setComponents(self, *args, **kwargs):
for idx, value in enumerate(args):
self[idx] = value
for k in kwargs:
self[k] = kwargs[k]
return self
def __len__(self):
return len(self._componentValues)
def clear(self):
self._componentValues = []
# backward compatibility
def setDefaultComponents(self):
pass
def getComponentType(self):
return self.componentType