Open Media Library Platform

Darwin/lib/python2.7/site-packages/twisted/protocols/stateful.py

@@ -0,0 +1,52 @@
+# -*- test-case-name: twisted.test.test_stateful -*-
+
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+
+from twisted.internet import protocol
+
+try:
+    from cStringIO import StringIO
+except ImportError:
+    from StringIO import StringIO
+
+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(), StringIO(), 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
+