FramedPacket: add new Packetizer variant that is looking for START and STOP

1 files changed, 48 insertions, 0 deletions

diff --git a/serial/threaded/__init__.py b/serial/threaded/__init__.py
index 00bf405..5fd3bc9 100644
--- a/serial/threaded/__init__.py
+++ b/serial/threaded/__init__.py
@@ -66,6 +66,54 @@ class Packetizer(Protocol):
         raise NotImplementedError('please implement functionality in handle_packet')
 
 
+class FramedPacket(Protocol):
+    """
+    Read binary packets. Packets are expected to have a start and stop marker.
+
+    The class also keeps track of the transport.
+    """
+
+    START = b'('
+    STOP = b')'
+
+    def __init__(self):
+        self.packet = bytearray()
+        self.in_packet = False
+        self.transport = None
+
+    def connection_made(self, transport):
+        """Store transport"""
+        self.transport = transport
+
+    def connection_lost(self, exc):
+        """Forget transport"""
+        self.transport = None
+        self.in_packet = False
+        del self.packet[:]
+
+    def data_received(self, data):
+        """Find data enclosed in START/STOP, call handle_packet"""
+        for byte in serial.iterbytes(data):
+            if byte == self.START:
+                self.in_packet = True
+            elif byte == self.STOP:
+                self.in_packet = False
+                self.handle_packet(packet)
+                del self.packet[:]
+            elif self.in_packet:
+                self.packet.append(byte)
+            else:
+                self.handle_out_of_packet_data(byte)
+
+    def handle_packet(self, packet):
+        """Process packets - to be overridden by subclassing"""
+        raise NotImplementedError('please implement functionality in handle_packet')
+
+    def handle_out_of_packet_data(self, data):
+        """Process data that is received outside of packets"""
+        pass
+
+
 class LineReader(Packetizer):
     """
     Read and write (Unicode) lines from/to serial port.