385 lines
14 KiB
Python
385 lines
14 KiB
Python
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"""Finite State Machine module: contains the ClassicFSM class.
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.. note::
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This module and class exist only for backward compatibility with
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existing code. New code should use the :mod:`.FSM` module instead.
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"""
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__all__ = ['ClassicFSM']
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from direct.directnotify.DirectNotifyGlobal import directNotify
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from direct.showbase.DirectObject import DirectObject
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import weakref
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if __debug__:
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_debugFsms = {}
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def printDebugFsmList():
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global _debugFsms
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for k in sorted(_debugFsms.keys()):
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print("%s %s" % (k, _debugFsms[k]()))
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__builtins__['debugFsmList'] = printDebugFsmList
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class ClassicFSM(DirectObject):
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"""
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Finite State Machine class.
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This module and class exist only for backward compatibility with
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existing code. New code should use the FSM class instead.
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"""
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# create ClassicFSM DirectNotify category
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notify = directNotify.newCategory("ClassicFSM")
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# special methods
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# these are flags that tell the ClassicFSM what to do when an
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# undefined transition is requested:
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ALLOW = 0 # print a warning, and do the transition
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DISALLOW = 1 # silently ignore the request (don't do the transition)
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DISALLOW_VERBOSE = 2 # print a warning, and don't do the transition
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ERROR = 3 # print an error message and raise an exception
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def __init__(self, name, states=[], initialStateName=None,
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finalStateName=None, onUndefTransition=DISALLOW_VERBOSE):
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"""__init__(self, string, State[], string, string, int)
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ClassicFSM constructor: takes name, list of states, initial state and
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final state as:
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fsm = ClassicFSM.ClassicFSM('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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each state's last argument, a list of allowed state transitions,
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is optional; if left out (or explicitly specified to be
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State.State.Any) then any transition from the state is 'defined'
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and allowed
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'onUndefTransition' flag determines behavior when undefined
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transition is requested; see flag definitions above
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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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self.onUndefTransition = onUndefTransition
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# Flag to see if we are inspecting
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self.inspecting = 0
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# We do not enter the initial state to separate
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# construction from activation
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self.__currentState = None
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# We set this while we are modifying the state. No one else
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# should recursively attempt to modify the state while we are
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# doing this.
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self.__internalStateInFlux = 0
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if __debug__:
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global _debugFsms
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_debugFsms[name]=weakref.ref(self)
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# I know this isn't how __repr__ is supposed to be used, but it
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# is nice and convenient.
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def __repr__(self):
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return self.__str__()
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def __str__(self):
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"""
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Print out something useful about the fsm
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"""
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currentState = self.getCurrentState()
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if currentState:
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str = ("ClassicFSM " + self.getName() + ' in state "' +
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currentState.getName() + '"')
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else:
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str = ("ClassicFSM " + self.getName() + ' not in any state')
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return str
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def enterInitialState(self, argList=[]):
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assert not self.__internalStateInFlux
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if self.__currentState == self.__initialState:
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return
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assert self.__currentState == None
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self.__internalStateInFlux = 1
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self.__enter(self.__initialState, argList)
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assert not self.__internalStateInFlux
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# setters and getters
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def getName(self):
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return(self.__name)
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def setName(self, name):
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self.__name = name
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def getStates(self):
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return list(self.__states.values())
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def setStates(self, states):
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"""setStates(self, State[])"""
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# Make a dictionary from stateName -> state
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self.__states = {}
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for state in states:
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self.__states[state.getName()] = state
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def addState(self, state):
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self.__states[state.getName()] = state
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def getInitialState(self):
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return(self.__initialState)
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def setInitialState(self, initialStateName):
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self.__initialState = self.getStateNamed(initialStateName)
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def getFinalState(self):
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return(self.__finalState)
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def setFinalState(self, finalStateName):
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self.__finalState = self.getStateNamed(finalStateName)
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def requestFinalState(self):
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self.request(self.getFinalState().getName())
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def 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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"""
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Return the state with given name if found, issue warning otherwise
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"""
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state = self.__states.get(stateName)
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if state:
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return state
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else:
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ClassicFSM.notify.warning("[%s]: getStateNamed: %s, no such state" %
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(self.__name, stateName))
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def hasStateNamed(self, stateName):
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"""
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Return True if stateName is a valid state, False otherwise.
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"""
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result = False
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state = self.__states.get(stateName)
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if state:
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result = True
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return result
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# basic ClassicFSM functionality
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def __exitCurrent(self, argList):
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"""
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Exit the current state
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"""
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assert self.__internalStateInFlux
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assert ClassicFSM.notify.debug("[%s]: exiting %s" % (self.__name, self.__currentState.getName()))
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self.__currentState.exit(argList)
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# Only send the state change event if we are inspecting it
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# If this event turns out to be generally useful, we can
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# turn it on all the time, but for now nobody else is using it
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if self.inspecting:
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messenger.send(self.getName() + '_' +
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self.__currentState.getName() + '_exited')
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self.__currentState = None
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def __enter(self, aState, argList=[]):
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"""
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Enter a given state, if it exists
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"""
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assert self.__internalStateInFlux
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stateName = aState.getName()
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if (stateName in self.__states):
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assert ClassicFSM.notify.debug("[%s]: entering %s" % (self.__name, stateName))
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self.__currentState = aState
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# Only send the state change event if we are inspecting it
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# If this event turns out to be generally useful, we can
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# turn it on all the time, but for now nobody else is using it
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if self.inspecting:
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messenger.send(self.getName() + '_' + stateName + '_entered')
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# Once we begin entering the new state, we're allow to
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# recursively request a transition to another state.
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# Indicate this by marking our internal state no longer in
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# flux.
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self.__internalStateInFlux = 0
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aState.enter(argList)
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else:
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# notify.error is going to raise an exception; reset the
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# flux flag first
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self.__internalStateInFlux = 0
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ClassicFSM.notify.error("[%s]: enter: no such state" % (self.__name))
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def __transition(self, aState, enterArgList=[], exitArgList=[]):
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"""
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Exit currentState and enter given one
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"""
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assert not self.__internalStateInFlux
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self.__internalStateInFlux = 1
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self.__exitCurrent(exitArgList)
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self.__enter(aState, enterArgList)
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assert not self.__internalStateInFlux
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def request(self, aStateName, enterArgList=[], exitArgList=[],
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force=0):
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"""
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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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"""
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# If you trigger this assertion failure, you must have
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# recursively requested a state transition from within the
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# exitState() function for the previous state. This is not
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# supported because we're not fully transitioned into the new
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# state yet.
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assert not self.__internalStateInFlux
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if not self.__currentState:
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# Make this a warning for now
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ClassicFSM.notify.warning("[%s]: request: never entered initial state" %
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(self.__name))
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self.__currentState = self.__initialState
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if isinstance(aStateName, str):
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aState = self.getStateNamed(aStateName)
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else:
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# Allow the caller to pass in a state in itself, not just
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# the name of a state.
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aState = aStateName
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aStateName = aState.getName()
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if aState == None:
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ClassicFSM.notify.error("[%s]: request: %s, no such state" %
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(self.__name, aStateName))
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# is the transition defined? if it isn't, should we allow it?
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transitionDefined = self.__currentState.isTransitionDefined(aStateName)
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transitionAllowed = transitionDefined
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if self.onUndefTransition == ClassicFSM.ALLOW:
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transitionAllowed = 1
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if not transitionDefined:
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# the transition is not defined, but we're going to do it
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# anyway. print a warning.
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ClassicFSM.notify.warning(
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"[%s]: performing undefined transition from %s to %s" %
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(self.__name,
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self.__currentState.getName(),
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aStateName))
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if transitionAllowed or force:
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self.__transition(aState,
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enterArgList,
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exitArgList)
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return 1
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# We can implicitly always transition to our final state.
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elif (aStateName == self.__finalState.getName()):
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if (self.__currentState == self.__finalState):
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# Do not do the transition if we are already in the
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# final state
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assert ClassicFSM.notify.debug(
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"[%s]: already in final state: %s" %
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(self.__name, aStateName))
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return 1
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else:
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# Force a transition to allow for cleanup
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assert ClassicFSM.notify.debug(
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"[%s]: implicit transition to final state: %s" %
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(self.__name, aStateName))
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self.__transition(aState,
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enterArgList,
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exitArgList)
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return 1
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# are we already in this state?
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elif (aStateName == self.__currentState.getName()):
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assert ClassicFSM.notify.debug(
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"[%s]: already in state %s and no self transition" %
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(self.__name, aStateName))
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return 0
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else:
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msg = ("[%s]: no transition exists from %s to %s" %
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(self.__name,
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self.__currentState.getName(),
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aStateName))
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if self.onUndefTransition == ClassicFSM.ERROR:
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ClassicFSM.notify.error(msg)
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elif self.onUndefTransition == ClassicFSM.DISALLOW_VERBOSE:
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ClassicFSM.notify.warning(msg)
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return 0
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def forceTransition(self, aStateName, enterArgList=[], exitArgList=[]):
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"""
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force a transition -- for debugging ONLY
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"""
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self.request(aStateName, enterArgList, exitArgList, force=1)
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def conditional_request(self, aStateName, enterArgList=[], exitArgList=[]):
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"""
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'if this transition is defined, do it'
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Attempt transition from currentState to given one, if it exists.
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Return true if transition exists to given state, false otherwise.
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It is NOT an error/warning to attempt a cond_request if the
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transition doesn't exist. This lets people be sloppy about
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ClassicFSM transitions, letting the same fn be used for different
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states that may not have the same out transitions.
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"""
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assert not self.__internalStateInFlux
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if not self.__currentState:
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# Make this a warning for now
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ClassicFSM.notify.warning("[%s]: request: never entered initial state" %
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(self.__name))
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self.__currentState = self.__initialState
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if isinstance(aStateName, str):
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aState = self.getStateNamed(aStateName)
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else:
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# Allow the caller to pass in a state in itself, not just
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# the name of a state.
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aState = aStateName
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aStateName = aState.getName()
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if aState == None:
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ClassicFSM.notify.error("[%s]: request: %s, no such state" %
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(self.__name, aStateName))
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transitionDefined = (
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self.__currentState.isTransitionDefined(aStateName) or
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aStateName in [self.__currentState.getName(),
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self.__finalState.getName()]
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)
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if transitionDefined:
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return self.request(aStateName, enterArgList, exitArgList)
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else:
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assert ClassicFSM.notify.debug(
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"[%s]: condition_request: %s, transition doesnt exist" %
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(self.__name, aStateName))
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return 0
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def view(self):
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# Don't use a regular import, to prevent ModuleFinder from picking
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# it up as a dependency when building a .p3d package.
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import importlib
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FSMInspector = importlib.import_module('direct.tkpanels.FSMInspector')
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FSMInspector.FSMInspector(self)
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def isInternalStateInFlux(self):
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return self.__internalStateInFlux
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