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from twisted.internet.defer import Deferred
from twisted.internet.endpoints import TCP4ServerEndpoint
from twisted.internet.protocol import Factory
from twisted.internet.task import react
from parsley import makeProtocol, stack
grammar = """
nonzeroDigit = digit:x ?(x != '0')
digits = <'0' | nonzeroDigit digit*>:i -> int(i)
netstring = digits:length ':' <anything{length}>:string ',' -> string
receiveNetstring = netstring:string -> receiver.netstringReceived(string)
"""
class NetstringReversalWrapper(object):
def __init__(self, wrapped):
self.wrapped = wrapped
def sendNetstring(self, string):
self.wrapped.sendNetstring(string[::-1])
class NetstringSender(object):
def __init__(self, transport):
self.transport = transport
def sendNetstring(self, string):
self.transport.write('%d:%s,' % (len(string), string))
class NetstringSplittingWrapper(object):
def __init__(self, wrapped):
self.wrapped = wrapped
def netstringReceived(self, string):
splitpoint = len(string) // 2
self.wrapped.netstringFirstHalfReceived(string[:splitpoint])
self.wrapped.netstringSecondHalfReceived(string[splitpoint:])
def __getattr__(self, attr):
return getattr(self.wrapped, attr)
class SplitNetstringReceiver(object):
currentRule = 'receiveNetstring'
def __init__(self, sender):
self.sender = sender
def prepareParsing(self, parser):
pass
def finishParsing(self, reason):
pass
def netstringFirstHalfReceived(self, string):
self.sender.sendNetstring(string)
def netstringSecondHalfReceived(self, string):
pass
pass # begin protocol definition
NetstringProtocol = makeProtocol(
grammar,
stack(NetstringReversalWrapper, NetstringSender),
stack(NetstringSplittingWrapper, SplitNetstringReceiver))
class NetstringFactory(Factory):
protocol = NetstringProtocol
def main(reactor):
server = TCP4ServerEndpoint(reactor, 1234)
d = server.listen(NetstringFactory())
d.addCallback(lambda p: Deferred()) # listen forever
return d
react(main, [])
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