def range(self, parameters, entries_stack=None):
if entries_stack is None:
entries_stack = set()
if self.entry in entries_stack:
# We can't keep recursing...
return Range()
entries_stack.add(self.entry)
if isinstance(self.entry, fld.Field):
length_range = expression_range(self.entry.length, self.entry, parameters, entries_stack)
# If our length is of a variable range, it can be very large.
# Attempting to take a power of a large number takes a very long
# time, is is quite meaningless; limit it to 64 bits.
max_length = min(length_range.max, 64)
result = Range(0, pow(2, max_length) - 1)
elif isinstance(self.entry, seq.Sequence):
result = expression_range(self.entry.value, self.entry, parameters, entries_stack)
elif isinstance(self.entry, chc.Choice):
ranges = [EntryValueType(child.entry).range(parameters, entries_stack) for child in self.entry.children]
result = reduce(Range.union, ranges)
else:
raise NotImplementedError("Don't know how to query the value range of entry '%s'!'" % self.entry)
entries_stack.remove(self.entry)
for constraint in self.entry.constraints:
result = result.intersect(constraint.range())
return result
def test_intersect_with_none(self):
a = Range(None, None)
b = Range(0, 10)
self.assertEqual(Range(0, 10), a.intersect(b))