def test_factlist_changes():
""" Test factlist changes """
from experta.factlist import FactList
from experta import Fact
flist = FactList()
f0 = flist.declare(Fact(a=1))
assert flist.changes[0] == [f0]
f1 = flist.declare(Fact(b=1))
assert flist.changes[0] == [f1]
flist.retract(f1)
assert flist.changes[1] == [f1]
def test_factlist_retract():
""" Test retract method """
from experta.factlist import FactList
from experta import Fact
flist = FactList()
assert getattr(flist, "last_index") == 0
assert not flist
flist.declare(Fact())
assert getattr(flist, "last_index") == 1
assert isinstance(flist[0], Fact)
assert flist.retract(0) == 0
assert not flist
class KnowledgeEngine:
"""
This represents a clips' ``module``, wich is an ``inference engine``
holding a set of ``rules`` (as :obj:`experta.rule.Rule` objects),
an ``agenda`` (as :obj:`experta.agenda.Agenda` object)
and a ``fact-list`` (as :obj:`experta.factlist.FactList` objects)
This could be considered, when inherited from, as the
``knowlege-base``.
"""
from experta.matchers import ReteMatcher as __matcher__
from experta.strategies import DepthStrategy as __strategy__
def __init__(self):
self.running = False
self.facts = FactList()
self.agenda = Agenda()
if (isinstance(self.__matcher__, type)
and issubclass(self.__matcher__, abstract.Matcher)):
self.matcher = self.__matcher__(self)
else:
raise TypeError("__matcher__ must be a subclass of Matcher")
if (isinstance(self.__strategy__, type)
and issubclass(self.__strategy__, abstract.Strategy)):
self.strategy = self.__strategy__()
else:
raise TypeError("__strategy__ must be a subclass of Strategy")
@staticmethod
def _get_real_modifiers(**modifiers):
for k, v in modifiers.items():
if k.startswith('_') and k[1:].isnumeric():
yield (int(k[1:]), v)
else:
yield (k, v)
def modify(self, declared_fact, **modifiers):
"""
Modifies a fact.
Facts are inmutable in Clips, thus, as documented in clips
reference manual, this retracts a fact and then re-declares it
`modifiers` must be a Mapping object containing keys and values
to be changed.
To allow modifying positional facts, the user can pass a string
containing the symbol "_" followed by the numeric index
(starting with 0). Ex::
>>> ke.modify(my_fact, _0="hello", _1="world", other_key="!")
"""
self.retract(declared_fact)
newfact = declared_fact.copy()
newfact.update(dict(self._get_real_modifiers(**modifiers)))
return self.declare(newfact)
def duplicate(self, template_fact, **modifiers):
"""Create a new fact from an existing one."""
newfact = template_fact.copy()
newfact.update(dict(self._get_real_modifiers(**modifiers)))
return self.declare(newfact)
@DefFacts(order=-1)
def _declare_initial_fact(self):
yield InitialFact()
def _get_by_type(self, wanted_type):
for _, obj in inspect.getmembers(self):
if isinstance(obj, wanted_type):
obj.ke = self
yield obj
def get_rules(self):
"""Return the existing rules."""
return list(self._get_by_type(Rule))
def get_deffacts(self):
"""Return the existing deffacts sorted by the internal order"""
return sorted(self._get_by_type(DefFacts), key=lambda d: d.order)
def get_activations(self):
"""
Return activations
"""
return self.matcher.changes(*self.facts.changes)
def retract(self, idx_or_declared_fact):
"""
Retracts a specific fact, using its index
.. note::
This updates the agenda
"""
self.facts.retract(idx_or_declared_fact)
if not self.running:
added, removed = self.get_activations()
self.strategy.update_agenda(self.agenda, added, removed)
def run(self, steps=float('inf')):
"""
Execute agenda activations
"""
self.running = True
activation = None
execution = 0
while steps > 0 and self.running:
added, removed = self.get_activations()
self.strategy.update_agenda(self.agenda, added, removed)
if watchers.worth('AGENDA', 'DEBUG'): # pragma: no cover
for idx, act in enumerate(self.agenda.activations):
watchers.AGENDA.debug("%d: %r %r", idx, act.rule.__name__,
", ".join(str(f) for f in act.facts))
activation = self.agenda.get_next()
if activation is None:
break
else:
steps -= 1
execution += 1
watchers.RULES.info(
"FIRE %s %s: %s", execution, activation.rule.__name__,
", ".join(str(f) for f in activation.facts))
activation.rule(
self, **{
k: v
for k, v in activation.context.items()
if not k.startswith('__')
})
self.running = False
def halt(self):
self.running = False
def reset(self, **kwargs):
"""
Performs a reset as per CLIPS behaviour (resets the
agenda and factlist and declares InitialFact())
Any keyword argument passed to `reset` will be passed to @DefFacts
which have those arguments on their signature.
.. note:: If persistent facts have been added, they'll be
re-declared.
"""
self.agenda = Agenda()
self.facts = FactList()
self.matcher.reset()
deffacts = []
for deffact in self.get_deffacts():
signature = inspect.signature(deffact)
if not any(p.kind == inspect.Parameter.VAR_KEYWORD
for p in signature.parameters.values()):
# There is not **kwargs defined. Pass only the defined
# names.
args = set(signature.parameters.keys())
deffacts.append(
deffact(**{k: v
for k, v in kwargs.items() if k in args}))
else:
deffacts.append(deffact(**kwargs))
# Declare all facts yielded by deffacts
self.__declare(*chain.from_iterable(deffacts))
self.running = False
def __declare(self, *facts):
"""
Internal declaration method. Used for ``declare`` and ``deffacts``
"""
if any(f.has_field_constraints() for f in facts):
raise TypeError(
"Declared facts cannot contain conditional elements")
elif any(f.has_nested_accessor() for f in facts):
raise KeyError(
"Cannot declare facts containing double underscores as keys.")
else:
last_inserted = None
for fact in facts:
last_inserted = self.facts.declare(fact)
if not self.running:
added, removed = self.get_activations()
self.strategy.update_agenda(self.agenda, added, removed)
return last_inserted
def declare(self, *facts):
"""
Declare from inside a fact, equivalent to ``assert`` in clips.
.. note::
This updates the agenda.
"""
if not self.facts:
watchers.ENGINE.warning("Declaring fact before reset()")
return self.__declare(*facts)