Refactor buffer parsing to serial packet descriptor

Source/ORSSerialPacketDescriptor.h

@@ -182,6 +182,15 @@ typedef BOOL(^ORSSerialPacketEvaluator)(NSData * __nullable inputData);
  */
 - (BOOL)dataIsValidPacket:(nullable NSData *)packetData;
 
+/**
+ *  Can be used to determine and extract a packet from a buffer, matching up to the end of the buffer.
+ *
+ *  @param buffer Data received from serial port.
+ *
+ *  @return Data corresponding to valid packet, or nil.
+ */
+- (nullable NSData *)packetMatchingAtEndOfBuffer:(nullable NSData *)buffer;
+
 /**
  *  The fixed packetData for packets described by the receiver. Will be nil for packet
  *  descriptors not created using -initWithPacketData:userInfo:

Source/ORSSerialPacketDescriptor.m

@@ -137,4 +137,14 @@ - (BOOL)dataIsValidPacket:(NSData *)packetData
 	return self.responseEvaluator(packetData);
 }
 
+- (NSData *)packetMatchingAtEndOfBuffer:(NSData *)buffer
+{
+	for (NSUInteger i=1; i<=[buffer length]; i++)
+	{
+		NSData *window = [buffer subdataWithRange:NSMakeRange([buffer length]-i, i)];
+		if ([self dataIsValidPacket:window]) return window;
+	}
+	return nil;
+}
+
 @end

Source/ORSSerialPort.m

@@ -474,17 +474,6 @@ - (void)stopListeningForPacketsMatchingDescriptor:(ORSSerialPacketDescriptor *)d
 
 #pragma mark - Private Methods
 
-// Must only be called on requestHandlingQueue (ie. wrap call to this method in dispatch())
-- (NSData *)packetMatchingDescriptor:(ORSSerialPacketDescriptor *)descriptor atEndOfBuffer:(NSData *)buffer
-{
-	for (NSUInteger i=1; i<=[buffer length]; i++)
-	{
-		NSData *window = [buffer subdataWithRange:NSMakeRange([buffer length]-i, i)];
-		if ([descriptor dataIsValidPacket:window]) return window;
-	}
-	return nil;
-}
-
 // Must only be called on requestHandlingQueue (ie. wrap call to this method in dispatch())
 - (BOOL)reallySendRequest:(ORSSerialRequest *)request
 {
@@ -558,7 +547,7 @@ - (void)checkResponseToPendingRequestAndContinueIfValidWithReceivedByte:(NSData
 	}
 
 	[self.requestResponseReceiveBuffer appendData:byte];
-	NSData *responseData = [self packetMatchingDescriptor:packetDescriptor atEndOfBuffer:self.requestResponseReceiveBuffer.data];
+	NSData *responseData = [packetDescriptor packetMatchingAtEndOfBuffer:self.requestResponseReceiveBuffer.data];
 	if (!responseData) return;
 
 	self.pendingRequestTimeoutTimer = nil;
@@ -600,7 +589,7 @@ - (void)receiveData:(NSData *)data;
 				[buffer appendData:byte];
 
 				// Check for complete packet
-				NSData *completePacket = [self packetMatchingDescriptor:descriptor atEndOfBuffer:buffer.data];
+				NSData *completePacket = [descriptor packetMatchingAtEndOfBuffer:buffer.data];
 				if (![completePacket length]) continue;
 
 				// Complete packet received, so notify delegate then clear buffer