Initial commit

app/StateMachine.py

@@ -0,0 +1,53 @@
+from collections import defaultdict
+from threading import RLock
+
+from app.EventBus import Event
+from app.util import ensure_list, matcher
+
+EVENT_STATE_CHANGED = "state_changed"
+
+class StateMachine:
+
+	def __init__(self, eventBus):
+		self.states = dict()
+		self.eventBus = eventBus
+		self.lock = RLock()
+
+	def add_category(self, category, initialState):
+		self.states[category] = initialState
+
+	def set_state(self, category, newState):
+		self.lock.acquire()
+
+		assert category in self.states, "Category does not exist: {}".format(category)
+		
+		oldState = self.states[category]
+
+		if oldState != newState:
+			self.states[category] = newState
+
+			self.eventBus.fire(Event(EVENT_STATE_CHANGED, {'category':category, 'oldState':oldState, 'newState':newState}))
+
+		self.lock.release()
+
+	def get_state(self, category):
+		assert category in self.states, "Category does not exist: {}".format(category)
+
+		return self.states[category]		
+
+
+def track_state_change(eventBus, category, fromState, toState, action):
+	fromState = ensure_list(fromState)
+	toState = ensure_list(toState)
+
+	def listener(event):
+		assert isinstance(event, Event), "event needs to be of Event type"
+
+		if category == event.data['category'] and \
+			matcher(event.data['oldState'], fromState) and \
+			matcher(event.data['newState'], toState):
+			
+			action(event.data['category'], event.data['oldState'], event.data['newState'])
+
+	eventBus.listen(EVENT_STATE_CHANGED, listener)
+