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Viewing changes to Vertex/vertex/statemachine.py

  • Committer: glyph
  • Date: 2005-08-04 20:40:55 UTC
  • Revision ID: svn-v4:866e43f7-fbfc-0310-8f2a-ec88d1da2979:trunk:20
yay internet

new q2q stuff

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Vertex/vertex/statemachine.py
 
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# -*- test-case-name: vertex.test.test_statemachine -*-
 
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NOTHING = 'nothing'             # be quiet (no output)
 
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class StateMachine:
 
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    initialState = None         # a str describing initial state
 
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    states = None     # dict, mapping state to dict of str input: (str output,
 
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                      # str new-state)
 
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    def __init__(self, initialState=None):
 
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        if initialState is None:
 
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            initialState = self.initialState
 
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        self.state = self.initialState
 
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    def transition(self, oldstate, newstate, datum, *a, **kw):
 
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        exitmeth = getattr(self, 'exit_%s' % (oldstate,), None)
 
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        entermeth = getattr(self, 'enter_%s' % (newstate,), None)
 
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        transmeth = getattr(self, 'transition_%s_to_%s' % (
 
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                oldstate.upper(), newstate.upper()), None)
 
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        for meth in exitmeth, entermeth, transmeth:
 
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            if meth is not None:
 
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                meth(*a, **kw)
 
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        self.state = newstate
 
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    def input(self, datum, *a, **kw):
 
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        oldstate = self.state
 
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        if datum == NOTHING:
 
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            return
 
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        output, newstate = self.states[self.state][datum]
 
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        OLDSTATE = self.state
 
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        NEWSTATE = newstate.upper()
 
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        DATUM = datum.upper()
 
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        self.transition(OLDSTATE, NEWSTATE, DATUM, *a, **kw)
 
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        self.output(output, *a, **kw)
 
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    def output(self, datum, *a, **kw):
 
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        foo = getattr(self, 'output_' + datum.upper(), None)
 
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        if foo is not None:
 
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            foo(*a, **kw)