# Copyright 2015-2016, Tresys Technology, LLC # Copyright 2018, Chris PeBenito <pebenito@ieee.org> # # SPDX-License-Identifier: LGPL-2.1-only # from collections import defaultdict from ..policyrep import Conditional from .difference import Wrapper from .typing import Cache _cond_cache: Cache[Conditional, "ConditionalWrapper"] = defaultdict(dict) def conditional_wrapper_factory(cond: Conditional) -> "ConditionalWrapper": """ Wrap type attributes from the specified policy. This caches results to prevent duplicate wrapper objects in memory. """ try: return _cond_cache[cond.policy][cond] except KeyError: a = ConditionalWrapper(cond) _cond_cache[cond.policy][cond] = a return a class ConditionalWrapper(Wrapper[Conditional]): """Wrap conditional policy expressions to allow comparisons by truth table.""" __slots__ = ("truth_table") def __init__(self, cond: Conditional) -> None: self.origin = cond self.truth_table = cond.truth_table() def __hash__(self): return hash(self.origin) def __eq__(self, other): return self.truth_table == other.truth_table def __lt__(self, other): return str(self.origin) < str(other)