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class StateMachine(object): |
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''' |
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Abstract simple character-driven state-machine for string transforms. |
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Useful for implementig simple transpilations, compressors and so on. |
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Important: when implementing this class, you must set the :attr:`current` |
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attribute to a key defined in :attr:`jumps` dict. |
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''' |
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jumps = {} # state machine jumps |
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start = '' # character which started current state |
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current = '' # initial and current state |
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pending = '' # buffer of current state data |
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streaming = False # stream mode toggle |
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@property |
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def nearest(self): |
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try: |
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options = self.jumps[self.current] |
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except KeyError: |
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raise KeyError( |
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'Current state %r not defined in %s.jumps.' |
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% (self.current, self.__class__) |
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) |
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offset = len(self.start) |
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index = len(self.pending) |
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if self.streaming: |
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index -= max(map(len, options)) |
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key = (index, 1) |
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result = (index, '', None) |
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for amark, anext in options.items(): |
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asize = len(amark) |
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aindex = self.pending.find(amark, offset, index + asize) |
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if aindex > -1: |
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index = aindex |
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akey = (aindex, -asize) |
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if akey < key: |
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key = akey |
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result = (aindex, amark, anext) |
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return result |
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def __init__(self, data=''): |
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self.pending = data |
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def __iter__(self): |
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''' |
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Iterate over tramsformation result chunks. |
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On non-streaming mode, flush and yield it on completion. |
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:yields: transformation result chunka |
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:ytype: str |
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''' |
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index, mark, next = self.nearest |
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while next is not None: |
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data = self.transform(self.pending[:index], mark, next) |
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self.start = mark |
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self.current = next |
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self.pending = self.pending[index:] |
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if data: |
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yield data |
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index, mark, next = self.nearest |
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if not self.streaming: |
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data = self.transform(self.pending, mark, next) |
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self.start = '' |
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self.pending = '' |
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if data: |
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yield data |
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def transform(self, data, mark, next): |
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method = getattr(self, 'transform_%s' % self.current, None) |
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return method(data, mark, next) if method else data |
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def feed(self, data=''): |
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self.streaming = True |
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self.pending += data |
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for i in self: |
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yield i |
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def finish(self, data=''): |
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self.pending += data |
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self.streaming = False |
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for i in self: |
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yield i |
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ergoithz /
browsepy
