32 lines
1.0 KiB
Python
32 lines
1.0 KiB
Python
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class InitializationError(Exception): pass
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class StateMachine:
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def __init__(self):
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self.handlers = []
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self.startState = None
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self.endStates = []
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def add_state(self, handler, end_state=0):
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self.handlers.append(handler)
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if end_state:
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self.endStates.append(handler)
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def set_start(self, handler):
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self.startState = handler
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def run(self, cargo=None):
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if not self.startState:
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raise InitializationError,\
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"must call .set_start() before .run()"
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if not self.endStates:
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raise InitializationError, \
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"at least one state must be an end_state"
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handler = self.startState
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while 1:
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(newState, cargo) = handler(cargo)
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if newState in self.endStates:
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newState(cargo)
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break
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elif newState not in self.handlers:
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raise RuntimeError, "Invalid target %s" % newState
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else:
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handler = newState
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