"""
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 types
import string
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, why:
raise error.ValueConstraintError('%s failed at: %s' % (
self, why
))
def __repr__(self):
return '%s(%s)' % (
self.__class__.__name__,
string.join(map(lambda x: str(x), self._values), ', ')
)
# __cmp__ must accompany __hash__
def __cmp__(self, other):
return self is other and 0 or cmp(
(self.__class__, self._values), other
)
def __eq__(self, other):
return self is other or not cmp(
(self.__class__, self._values), other
)
def __hash__(self):
if self.__hashedValues is None:
self.__hashedValues = hash((self.__class__, 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 otherConstraint.getValueMap().has_key(self) or \
otherConstraint is self or otherConstraint == self
def isSubTypeOf(self, otherConstraint):
return self._valueMap.has_key(otherConstraint) 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): pass
# 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 not self.__multipleTypeConstraint.has_key(idx):
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 type(v) == types.TupleType:
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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