def execute(self, agent, intention):
# Boolean constants.
term = pyson.evaluate(self.term, intention.scope)
if term is True:
yield
return
elif term is False:
return
try:
group = term.literal_group()
except AttributeError:
raise PysonError(
"expected boolean or literal in query context, got: '%s'" %
term)
# Query on the belief base.
for belief in agent.beliefs[group]:
for _ in pyson.unify_annotated(term, belief, intention.scope,
intention.stack):
yield
choicepoint = object()
# Follow rules.
for rule in agent.rules[group]:
rule = copy.deepcopy(rule)
intention.stack.append(choicepoint)
if pyson.unify(term, rule.head, intention.scope, intention.stack):
for _ in rule.query.execute(agent, intention):
yield
pyson.reroll(intention.scope, intention.stack, choicepoint)
def call(self, trigger, goal_type, term, calling_intention, delayed=False):
if goal_type == pyson.GoalType.belief:
if trigger == pyson.Trigger.addition:
self.add_belief(term, calling_intention.scope)
else:
found = self.remove_belief(term, calling_intention)
if not found:
return True
frozen = pyson.freeze(term, calling_intention.scope, {})
if not isinstance(frozen, pyson.Literal):
raise PysonError("expected literal")
applicable_plans = self.plans[(trigger, goal_type, frozen.functor,
len(frozen.args))]
choicepoint = object()
intention = Intention()
for plan in applicable_plans:
for _ in pyson.unify_annotated(plan.head, frozen, intention.scope,
intention.stack):
for _ in plan.context.execute(self, intention):
intention.head_term = frozen
intention.instr = plan.body
intention.calling_term = term
if not delayed and self.intentions:
for intention_stack in self.intentions:
if intention_stack[-1] == calling_intention:
intention_stack.append(intention)
return True
new_intention_stack = collections.deque()
new_intention_stack.append(intention)
self.intentions.append(new_intention_stack)
return True
if goal_type == pyson.GoalType.achievement:
raise PysonError("no applicable plan for %s%s%s/%d" %
(trigger.value, goal_type.value, frozen.functor,
len(frozen.args)))
elif goal_type == pyson.GoalType.test:
return self.test_belief(term, calling_intention)
return True
def execute(self, agent, intention):
return pyson.unify_annotated(self.left, self.right, intention.scope,
intention.stack)