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67 lines
1.9 KiB
Python
67 lines
1.9 KiB
Python
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class EventSpec():
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def readfsm(self,file):
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# takes a filename, returns a finite state machine
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# fsm is (begin state, structure)
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fsm = {}
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with open(file) as f:
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s = None
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t = {}
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for l in f:
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ls = l.split()
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if (ls == []) or (ls[0][0] == "#"):
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continue
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if ls[0] == "state:":
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if s != None:
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if s in fsm:
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raise SyntaxError("Cannot define state " + s + " twice")
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fsm[s] = t
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s = ls[1]
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t = {}
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elif ls[1] == "->":
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t[ls[0]] = ls[2]
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elif ls[0] == "begin:":
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beginState = ls[1]
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else:
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raise SyntaxError(l + " is not a line in a finite state machine definition")
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if s != None:
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fsm[s] = t
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return (beginState, fsm)
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def __init__(self,file):
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(self.start, self.machine) = self.readfsm(file)
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self.state = self.start
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self.trace = []
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self.triggers = {}
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def onEvent(self, event, action):
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self.triggers[event] = action
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def reset(self):
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self.state = self.start
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self.trace = []
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def trace(self):
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return self.trace
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def state(self):
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return self.state
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def printLog(self):
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i = 0
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for (e,s) in self.trace:
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print " STEP #"+str(i)+":",e,"-->",s
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i += 1
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def event(self, event):
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try:
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self.state = self.machine[self.state][event]
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self.trace.append((event,self.state))
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if event in self.triggers:
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self.triggers[event]()
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except KeyError:
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raise RuntimeError("From state " + self.state + ", transition " + event + " is not allowed (trace: " + str(self.trace) + ")")
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