Add generic message framing wrapper to DataChannel (#12)

Sources/LanguageServerProtocol/Additions/DataChannel+MessageFraming.swift

@@ -0,0 +1,38 @@
+import Foundation
+import JSONRPC
+
+extension DataChannel {
+	/// Wrap http message framing on an existing data channel
+	public func withMessageFraming(
+	) -> DataChannel {
+
+		let writeHandler: DataChannel.WriteHandler = { data in
+			let data = MessageFraming.frame(data)
+
+			try await self.writeHandler(data)
+		}
+
+#if compiler(>=5.9)
+		let (stream, continuation) = DataSequence.makeStream()
+#else
+		var escapedContinuation: DataSequence.Continuation?
+
+		let stream = DataSequence  { escapedContinuation = $0 }
+		let continuation = escapedContinuation!
+#endif
+
+		Task {
+			let byteStream = AsyncByteSequence(base: dataSequence)
+			let framedData = AsyncMessageFramingSequence(base: byteStream)
+
+			for try await data in framedData {
+				continuation.yield(data)
+			}
+
+			continuation.finish()
+		}
+
+		return DataChannel(writeHandler: writeHandler,
+							dataSequence: stream)
+	}
+}