def check_action(self, node: _Node, state: State, action: Action) -> bool:
# Find the last action before a navigation action
# TODO: Fold this behaviour into ChainingOptions.check_action()
nav_parent = node
while nav_parent.action is not None and self._is_navigation(
nav_parent.action):
# HACK: Going through a door is always considered navigation unless the previous action was to open that door.
parent = nav_parent.parent
if parent.action is not None and parent.action.name == "open/d":
break
if self.backward and action.name == "open/d":
break
nav_parent = parent
if nav_parent.action is not None and not self._is_navigation(action):
if self.backward:
recent = action.inverse()
pre_navigation = recent
post_navigation = nav_parent.action.inverse()
else:
recent = node.action
pre_navigation = nav_parent.action
post_navigation = action
relevant = set(post_navigation.preconditions)
if len(recent.added & relevant) == 0 or len(pre_navigation.added
& relevant) == 0:
return False
return self.options.check_action(state, action)
def apply(self, node: _Node, action: Action) -> Optional[State]:
"""Attempt to apply an action to the given state."""
new_state = node.state.copy()
for prop in action.preconditions:
new_state.add_fact(prop)
# Make sure new_state still respects the constraints
if not self.check_state(new_state):
return None
new_state.apply(action)
# Detect cycles
state = new_state.copy()
state.apply(action.inverse())
while node.action:
state.apply(node.action.inverse())
if new_state == state:
return None
node = node.parent
return new_state