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#
# ASN.1 subtype constraints classes.
#
# Constraints are relatively rare, but every ASN1 object
# is doing checks all the time for whether they have any
# constraints and whether they are applicable to the object.
#
# What we're going to do is define objects/functions that
# can be called unconditionally if they are present, and that
# are simply not present if there are no constraints.
#
# Original concept and code by Mike C. Fletcher.
#
import sys
from pyasn1.type import error
class AbstractConstraint:
"""Abstract base-class for constraint objects
Constraints should be stored in a simple sequence in the
namespace of their client Asn1Item sub-classes.
"""
def __init__(self, *values):
self._valueMap = {}
self._setValues(values)
self.__hashedValues = None
def __call__(self, value, idx=None):
try:
self._testValue(value, idx)
except error.ValueConstraintError:
raise error.ValueConstraintError(
'%s failed at: \"%s\"' % (self, sys.exc_info()[1])
)
def __repr__(self):
return '%s(%s)' % (
self.__class__.__name__,
', '.join([repr(x) for x in self._values])
)
def __eq__(self, other):
return self is other and True or self._values == other
def __ne__(self, other): return self._values != other
def __lt__(self, other): return self._values < other
def __le__(self, other): return self._values <= other
def __gt__(self, other): return self._values > other
def __ge__(self, other): return self._values >= other
if sys.version_info[0] <= 2:
def __nonzero__(self): return bool(self._values)
else:
def __bool__(self): return bool(self._values)
def __hash__(self):
if self.__hashedValues is None:
self.__hashedValues = hash((self.__class__.__name__, self._values))
return self.__hashedValues
def _setValues(self, values): self._values = values
def _testValue(self, value, idx):
raise error.ValueConstraintError(value)
# Constraints derivation logic
def getValueMap(self): return self._valueMap
def isSuperTypeOf(self, otherConstraint):
return self in otherConstraint.getValueMap() or \
otherConstraint is self or otherConstraint == self
def isSubTypeOf(self, otherConstraint):
return otherConstraint in self._valueMap or \
otherConstraint is self or otherConstraint == self
class SingleValueConstraint(AbstractConstraint):
"""Value must be part of defined values constraint"""
def _testValue(self, value, idx):
# XXX index vals for performance?
if value not in self._values:
raise error.ValueConstraintError(value)
class ContainedSubtypeConstraint(AbstractConstraint):
"""Value must satisfy all of defined set of constraints"""
def _testValue(self, value, idx):
for c in self._values:
c(value, idx)
class ValueRangeConstraint(AbstractConstraint):
"""Value must be within start and stop values (inclusive)"""
def _testValue(self, value, idx):
if value < self.start or value > self.stop:
raise error.ValueConstraintError(value)
def _setValues(self, values):
if len(values) != 2:
raise error.PyAsn1Error(
'%s: bad constraint values' % (self.__class__.__name__,)
)
self.start, self.stop = values
if self.start > self.stop:
raise error.PyAsn1Error(
'%s: screwed constraint values (start > stop): %s > %s' % (
self.__class__.__name__,
self.start, self.stop
)
)
AbstractConstraint._setValues(self, values)
class ValueSizeConstraint(ValueRangeConstraint):
"""len(value) must be within start and stop values (inclusive)"""
def _testValue(self, value, idx):
l = len(value)
if l < self.start or l > self.stop:
raise error.ValueConstraintError(value)
class PermittedAlphabetConstraint(SingleValueConstraint):
def _setValues(self, values):
self._values = ()
for v in values:
self._values = self._values + tuple(v)
def _testValue(self, value, idx):
for v in value:
if v not in self._values:
raise error.ValueConstraintError(value)
# This is a bit kludgy, meaning two op modes within a single constraing
class InnerTypeConstraint(AbstractConstraint):
"""Value must satisfy type and presense constraints"""
def _testValue(self, value, idx):
if self.__singleTypeConstraint:
self.__singleTypeConstraint(value)
elif self.__multipleTypeConstraint:
if idx not in self.__multipleTypeConstraint:
raise error.ValueConstraintError(value)
constraint, status = self.__multipleTypeConstraint[idx]
if status == 'ABSENT': # XXX presense is not checked!
raise error.ValueConstraintError(value)
constraint(value)
def _setValues(self, values):
self.__multipleTypeConstraint = {}
self.__singleTypeConstraint = None
for v in values:
if isinstance(v, tuple):
self.__multipleTypeConstraint[v[0]] = v[1], v[2]
else:
self.__singleTypeConstraint = v
AbstractConstraint._setValues(self, values)
# Boolean ops on constraints
class ConstraintsExclusion(AbstractConstraint):
"""Value must not fit the single constraint"""
def _testValue(self, value, idx):
try:
self._values[0](value, idx)
except error.ValueConstraintError:
return
else:
raise error.ValueConstraintError(value)
def _setValues(self, values):
if len(values) != 1:
raise error.PyAsn1Error('Single constraint expected')
AbstractConstraint._setValues(self, values)
class AbstractConstraintSet(AbstractConstraint):
"""Value must not satisfy the single constraint"""
def __getitem__(self, idx): return self._values[idx]
def __add__(self, value): return self.__class__(self, value)
def __radd__(self, value): return self.__class__(self, value)
def __len__(self): return len(self._values)
# Constraints inclusion in sets
def _setValues(self, values):
self._values = values
for v in values:
self._valueMap[v] = 1
self._valueMap.update(v.getValueMap())
class ConstraintsIntersection(AbstractConstraintSet):
"""Value must satisfy all constraints"""
def _testValue(self, value, idx):
for v in self._values:
v(value, idx)
class ConstraintsUnion(AbstractConstraintSet):
"""Value must satisfy at least one constraint"""
def _testValue(self, value, idx):
for v in self._values:
try:
v(value, idx)
except error.ValueConstraintError:
pass
else:
return
raise error.ValueConstraintError(
'all of %s failed for \"%s\"' % (self._values, value)
)
# XXX
# add tests for type check
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