# 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)
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