class Rule:
'''
In-memory representation of logic-engine rule, relying on parsing utilities in BooleanExpression.
'''
def __init__(self, rule_name, rule_cfg):
self.name = rule_name
self.expr = BooleanExpression(rule_cfg["expression"])
self.actions = rule_cfg.get("actions")
self.false_actions = rule_cfg.get("false_actions")
self.new_facts = rule_cfg.get("facts")
def evaluate(self, evaluated_facts):
"""
Evaluates a compiled expression given the supplied facts.
:type evaluated_facts: dict
:arg evaluated_facts: Initial fact values (e.g. True or False) for each fact name.
:rtype: bool
"""
return self.expr.evaluate(evaluated_facts)
def __str__(self): # pragma: no cover
return f"name: {self.name}\n"
f"expression: '{self.expr}'\n"
f"actions: {self.actions}\n"
f"false_actions: {self.false_actions}\n"
f"facts: {self.new_facts}"
def __init__(self, cfg):
super().__init__(cfg)
self.logger = logging.getLogger()
self.facts = {
name: BooleanExpression(expr)
for name, expr in cfg["facts"].items()
}
self.rule_engine = RuleEngine(cfg["facts"].keys(), cfg["rules"])
def __init__(self, cfg):
super().__init__(cfg)
self.logger = structlog.getLogger(CHANNELLOGGERNAME)
self.logger = self.logger.bind(class_module=__name__.split(".")[-1],
channel=self.channel_name)
self.facts = {
name: BooleanExpression(expr)
for name, expr in cfg["facts"].items()
}
self.rule_engine = RuleEngine(cfg["facts"].keys(), cfg["rules"])
def test_compound_fact():
fact = BooleanExpression("z < 100 and a == 4")
assert set(fact.required_names) == {"z", "a"}
assert fact.evaluate({"z": 50, "a": 4}) is True
assert fact.evaluate({"z": 100, "a": 4}) is False
assert fact.evaluate({"z": 200, "a": 4}) is False
assert fact.evaluate({"z": 200, "a": 5}) is False
assert fact.evaluate({"z": 100, "a": 5}) is False
assert fact.evaluate({"z": 50, "a": 5}) is False
def __init__(self, rule_name, rule_cfg):
self.name = rule_name
self.expr = BooleanExpression(rule_cfg["expression"])
self.actions = rule_cfg.get("actions")
self.false_actions = rule_cfg.get("false_actions")
self.new_facts = rule_cfg.get("facts")
def test_fact_using_numpy_function():
fact = BooleanExpression("np.sum(vals) > 40")
assert set(fact.required_names) == {"vals", "np"}
with pytest.raises(Exception, match="name 'np' is not defined"):
fact.evaluate(make_db(3))
def test_simple_fact():
fact = BooleanExpression("z < 100")
assert fact.required_names == ["z"]
assert fact.evaluate({"z": 50}) is True
assert fact.evaluate({"z": 100}) is False
assert fact.evaluate({"z": 200}) is False
def test_fact_using_numpy_array():
fact = BooleanExpression("vals.sum() > 40")
assert fact.required_names == ["vals"]
assert fact.evaluate(make_db(3)) is False
assert fact.evaluate(make_db(10)) is True
def test_fact_with_nested_names():
fact = BooleanExpression("z > 100 and b.c == 10")
assert set(fact.required_names) == {"z", "b"}
def test_fact_with_fail_on_error():
fact = BooleanExpression("fail_on_error(a[0])")
assert set(fact.required_names) == {"a"}
def test_syntax_error(caplog):
with pytest.raises(SyntaxError):
BooleanExpression("z <")
assert "The following expression string could not be parsed" in caplog.text