参考教程
https://python-course.eu/applications-python/finite-state-machine.php
代码实现
class InitializationError(Exception):passclass StateMachine:def __init__(self):self.handlers = {}self.startState = Noneself.endStates = []def add_state(self, name, handler, end_state=0):name = name.upper()self.handlers[name] = handlerif end_state:self.endStates.append(name)def set_start(self, name):self.startState = name.upper()def run(self, cargo):try:handler = self.handlers[self.startState]except:raise InitializationError("must call .set_start() before .run()")if not self.endStates:raise InitializationError("at least one state must be an end_state")while True:(newState, cargo) = handler(cargo)if newState.upper() in self.endStates:print("reached ", newState)breakelse:handler = self.handlers[newState.upper()]positive_adjectives = ["great", "super", "fun", "entertaining", "easy"]
negative_adjectives = ["boring", "difficult", "ugly", "bad"]def start_transitions(txt):split_txt = txt.split(None, 1)word, txt = split_txt if len(split_txt) > 1 else (txt, "")if word == "Python":newState = "Python_state"else:newState = "error_state"return newState, txtdef python_state_transitions(txt):split_txt = txt.split(None, 1)word, txt = split_txt if len(split_txt) > 1 else (txt, "")if word == "is":newState = "is_state"else:newState = "error_state"return newState, txtdef is_state_transitions(txt):split_txt = txt.split(None, 1)word, txt = split_txt if len(split_txt) > 1 else (txt, "")if word == "not":newState = "not_state"elif word in positive_adjectives:newState = "pos_state"elif word in negative_adjectives:newState = "neg_state"else:newState = "error_state"return newState, txtdef not_state_transitions(txt):split_txt = txt.split(None, 1)word, txt = split_txt if len(split_txt) > 1 else (txt, "")if word in positive_adjectives:newState = "neg_state"elif word in negative_adjectives:newState = "pos_state"else:newState = "error_state"return newState, txtdef neg_state(txt):print("Hallo")return "neg_state", ""if __name__ == '__main__':m = StateMachine()m.add_state("Start", start_transitions)m.add_state("Python_state", python_state_transitions)m.add_state("is_state", is_state_transitions)m.add_state("not_state", not_state_transitions)m.add_state("neg_state", None, end_state=1)m.add_state("pos_state", None, end_state=1)m.add_state("error_state", None, end_state=1)m.set_start("Start")m.run("Python is great")m.run("Python is difficult")m.run("Perl is ugly")
