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- # -*- test-case-name: twisted.test.test_stateful -*-
-
- # Copyright (c) Twisted Matrix Laboratories.
- # See LICENSE for details.
-
-
- from io import BytesIO
-
- from twisted.internet import protocol
-
-
- class StatefulProtocol(protocol.Protocol):
- """A Protocol that stores state for you.
-
- state is a pair (function, num_bytes). When num_bytes bytes of data arrives
- from the network, function is called. It is expected to return the next
- state or None to keep same state. Initial state is returned by
- getInitialState (override it).
- """
-
- _sful_data = None, None, 0
-
- def makeConnection(self, transport):
- protocol.Protocol.makeConnection(self, transport)
- self._sful_data = self.getInitialState(), BytesIO(), 0
-
- def getInitialState(self):
- raise NotImplementedError
-
- def dataReceived(self, data):
- state, buffer, offset = self._sful_data
- buffer.seek(0, 2)
- buffer.write(data)
- blen = buffer.tell() # how many bytes total is in the buffer
- buffer.seek(offset)
- while blen - offset >= state[1]:
- d = buffer.read(state[1])
- offset += state[1]
- next = state[0](d)
- if (
- self.transport.disconnecting
- ): # XXX: argh stupid hack borrowed right from LineReceiver
- return # dataReceived won't be called again, so who cares about consistent state
- if next:
- state = next
- if offset != 0:
- b = buffer.read()
- buffer.seek(0)
- buffer.truncate()
- buffer.write(b)
- offset = 0
- self._sful_data = state, buffer, offset
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