5

これらの F# 型宣言を考えると...

type Message =
    | MessageA
    | MessageB
    | MessageC
    | MessageD

type State = {
    Name:string
    NextStateMap: Map<Message,State>
}

...この特定の状態機械の同等に表現力豊かな定義はありますか...

let rec state0 = { Name = "0"; NextStateMap = Map.ofList [ (MessageA,state1); (MessageB,state2)] }
    and state1 = { Name = "1"; NextStateMap = Map.ofList [ (MessageB,state3)] }
    and state2 = { Name = "2"; NextStateMap = Map.ofList [ (MessageA,state3)] }
    and state3 = { Name = "3"; NextStateMap = Map.ofList [ (MessageC,state4)] }
    and state4 = { Name = "4"; NextStateMap = Map.ofList [ (MessageD,state5)] }
    and state5 = { Name = "5"; NextStateMap = Map.empty}

...Pythonで？

「rec」を介して、トポロジカルソートで定義された順序で割り当てを行う必要がないことに注意してください... (たとえば、state1 は後で定義されますが、state0 は state1 に関して定義されます)。

PS文字列を状態識別子として使用するオプション...

stateMachine = {
   "0" : { "A":"1", "B":"2"},
   "1" : { "B":"3" },
...

...無効なキー (つまり、ステート マシンの無効なメッセージ指定子) のケースを開いたままにします。

4

2 に答える 2

5

Python では、状態を定義してからマップを設定すると思います。次のような疑似コード:

state0 = State("0")
state1 = State("1")
... and so on ...
state0.next_states = {message_a: state1, message_b: state2 }
state1.next_states = {message_b: state3}
... and so on ...
于 2011-02-25T16:01:00.757 に答える
0 
## a generic state machine framework ###################

class Message(object):
    """
    This represents a message being passed to the
    state machine.
    """
    def __init__(self, name):
        self.name = name
    def __str__(self):
        return "Message(%r)" % self.name
    def __call__(self, smap):
        try:
            return smap[self]
        except KeyError:
            raise Exception("invalid message: %s vs %s"
                            % (self, smap))

class MessageFactory(object):
    """
    Since python doesn't have symbols, this automagically
    creates the messages for you. (It's purely for
    convenience, and you could just as easily instantiate
    each message by hand.
    """
    cache = {}
    def __getattr__(self, name):
        return self.cache.setdefault(name, Message(name))

class StateMachine(object):
    """
    This keeps track of the state, of course. :)
    """
    def __init__(self, state):
        self.state = state
    def __call__(self, msg):
        self.state = self.state(msg)


## how to set it up: ###################################

msg = MessageFactory()
state =\
{
    0 : lambda m: m({ msg.A : state[1],
                      msg.B : state[2] }),
    1 : lambda m: m({ msg.B : state[3] }),
    2 : lambda m: m({ msg.A : state[3] }),
    3 : lambda m: m({ msg.C : state[4] }),
    4 : lambda m: m({ msg.D : state[5] }),
    5 : lambda m: m({ }),
}

## how to use it: ######################################

s = StateMachine(state[0])
s(msg.A)
assert s.state is state[1]
于 2011-02-25T16:52:19.397 に答える