145 lines
4.1 KiB
Python
145 lines
4.1 KiB
Python
"""Finite State Machine module: contains the FSM class"""
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from DirectObject import *
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class FSM(DirectObject):
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"""FSM class: Finite State Machine class"""
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# create FSM DirectNotify category
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notify = directNotify.newCategory("FSM")
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# special methods
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def __init__(self, name, states=[], initialStateName=None,
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finalStateName=None):
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"""__init__(self, string, State[], string, string)
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FSM constructor: takes name, list of states, initial state and
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final state as:
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fsm = FSM.FSM('stopLight',
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[ State.State('red', enterRed, exitRed, ['green']),
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State.State('yellow', enterYellow, exitYellow, ['red']),
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State.State('green', enterGreen, exitGreen, ['yellow']) ],
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'red',
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'red')
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"""
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self.setName(name)
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self.setStates(states)
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self.setInitialState(initialStateName)
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self.setFinalState(finalStateName)
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#enter the initial state
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self.__currentState = self.__initialState
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self.__enter(self.__initialState)
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def __str__(self):
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"""__str__(self)"""
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return "FSM: name = %s \n states = %s \n initial = %s \n final = %s \n current = %s" % (self.__name, self.__states, self.__initialState, self.__finalState, self.__currentState)
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#setters and getters
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def getName(self):
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"""getName(self)"""
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return(self.__name)
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def setName(self, name):
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"""setName(self, string)"""
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self.__name = name
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def getStates(self):
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"""getStates(self)"""
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return(self.__states)
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def setStates(self, states):
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"""setStates(self, State[])"""
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self.__states = states
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def getInitialState(self):
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"""getInitialState(self)"""
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return(self.__initialState)
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def setInitialState(self, initialStateName):
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"""setInitialState(self, string)"""
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self.__initialState = self.getStateNamed(initialStateName)
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def getFinalState(self):
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"""getFinalState(self)"""
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return(self.__finalState)
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def setFinalState(self, finalStateName):
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"""setFinalState(self, string)"""
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self.__finalState = self.getStateNamed(finalStateName)
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def getCurrentState(self):
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"""getCurrentState(self)"""
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return(self.__currentState)
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# lookup funcs
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def getStateNamed(self, stateName):
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"""getStateNamed(self, string)
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Return the state with given name if found, issue warning otherwise"""
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for state in self.__states:
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if (state.getName() == stateName):
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return state
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FSM.notify.warning("getStateNamed: no such state")
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# basic FSM functionality
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def __exitCurrent(self):
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"""__exitCurrent(self)
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Exit the current state"""
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FSM.notify.info("exiting %s" % self.__currentState.getName())
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messenger.send(self.getName() + '_' +
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self.__currentState.getName() + '_exited')
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self.__currentState.exit()
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self.__currentState = None
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def __enter(self, aState):
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"""__enter(self, State)
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Enter a given state, if it exists"""
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if (aState in self.__states):
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self.__currentState = aState
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aState.enter()
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messenger.send(self.getName() + '_' +
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aState.getName() + '_entered')
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FSM.notify.info("entering %s" % aState.getName())
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else:
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FSM.notify.error("enter: no such state")
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def __transition(self, aState):
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"""__transition(self, State)
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Exit currentState and enter given one"""
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self.__exitCurrent()
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self.__enter(aState)
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def request(self, aStateName):
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"""request(self, string)
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Attempt transition from currentState to given one.
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Return true is transition exists to given state,
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false otherwise"""
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if (aStateName in self.__currentState.getTransitions()):
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self.__transition(self.getStateNamed(aStateName))
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return 1
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else:
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FSM.notify.info("no transition exists to %s" % aStateName)
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return 0
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