split client and server channels

pkg/analysis_server/lib/src/channel.dart

Index: pkg/analysis_server/lib/src/channel.dart
diff --git a/pkg/analysis_server/lib/src/channel.dart b/pkg/analysis_server/lib/src/channel.dart
index 859a393f5640987c28a02bdb1904168444d71240..e9fc95d859b85d8d43737a17fe3ba4c2e51504c3 100644
--- a/pkg/analysis_server/lib/src/channel.dart
+++ b/pkg/analysis_server/lib/src/channel.dart
@@ -10,11 +10,35 @@ import 'dart:io';
 import 'package:analysis_server/src/protocol.dart';
 
 /**
- * The abstract class [CommunicationChannel] defines the behavior of objects
- * that allow an [AnalysisServer] to receive [Request]s and to return both
- * [Response]s and [Notification]s.
+ * The abstract class [ClientCommunicationChannel] defines the behavior of
+ * objects that allows an object to send [Request]s to [AnalysisServer] and to
+ * receive both [Response]s and [Notification]s.
  */
-abstract class CommunicationChannel {
+abstract class ClientCommunicationChannel {
+  /**
+   * Listen to the channel for responses and notifications.
+   * If a response is received, invoke the [onResponse] function.
+   * If a notification is received, invoke the [onNotification] function.
+   * If an error is encountered while trying to read from
+   * the socket, invoke the [onError] function. If the socket is closed by the
+   * client, invoke the [onDone] function.
+   */
+  void listen(void onResponse(Response response),
+              void onNotification(Notification notification),
+              {void onError(), void onDone()});
+
+  /**
+   * Send the given [request] to the server.
+   */
+  void sendRequest(Request request);
+}
+
+/**
+ * The abstract class [ServerCommunicationChannel] defines the behavior of
+ * objects that allow an [AnalysisServer] to receive [Request]s and to return
+ * both [Response]s and [Notification]s.
+ */
+abstract class ServerCommunicationChannel {
   /**
    * Listen to the channel for requests. If a request is received, invoke the
    * [onRequest] function. If an error is encountered while trying to read from
@@ -29,21 +53,84 @@ abstract class CommunicationChannel {
   void sendNotification(Notification notification);
 
   /**
-   * Send the given [request] to the server.
+   * Send the given [response] to the client.
    */
-  void sendRequest(Request request);
+  void sendResponse(Response response);
+}
 
+/**
+ * Instances of the class [WebSocketClientChannel] implement a
+ * [ClientCommunicationChannel] that uses a [WebSocket] to communicate with
+ * servers.
+ */
+class WebSocketClientChannel implements ClientCommunicationChannel {
   /**
-   * Send the given [response] to the client.
+   * The socket being wrapped.
    */
-  void sendResponse(Response response);
+  final WebSocket socket;
+
+  final JsonEncoder jsonEncoder = const JsonEncoder(null);
+
+  final JsonDecoder jsonDecoder = const JsonDecoder(null);
+
+  /**
+   * Initialize a newly create [WebSocket] wrapper to wrap the given [socket].
+   */
+  WebSocketClientChannel(this.socket);
+
+  @override
+  void listen(void onResponse(Response response),
+              void onNotification(Notification notification),
+              {void onError(), void onDone()}) {
+    socket.listen((data) => _read(data, onResponse, onNotification),
+        onError: onError, onDone: onDone);
+  }
+
+  @override
+  void sendRequest(Request request) {
+    socket.add(jsonEncoder.convert(request.toJson()));
+  }
+
+  /**
+   * Read a request from the given [data] and use the given function to handle
+   * the request.
+   */
+  void _read(Object data,
+             void onResponse(Response response),
+             void onNotification(Notification notification)) {
+    if (data is String) {
+      // Parse the string as a JSON descriptor
+      var json;
+      try {
+        json = jsonDecoder.convert(data);
+        if (json is! Map) {
+          return;
+        }
+      } catch (error) {
+        return;
+      }
+      // Process the resulting structure as a response or notification.
+      if (json[Notification.EVENT] != null) {
+        Notification notification = new Notification.fromJson(json);
+        if (notification != null) {
+          onNotification(notification);
+        }
+      } else {
+        Response response = new Response.fromJson(json);
+        if (response != null) {
+          onResponse(response);
+        }
+      }
+    }
+  }
 }
 
 /**
- * Instances of the class [WebSocketChannel] implement a [CommunicationChannel]
- * that uses a [WebSocket] to communicate with clients.
+ * Instances of the class [WebSocketServerChannel] implement a
+ * [ServerCommunicationChannel] that uses a [WebSocket] to communicate with
+ * clients.
  */
-class WebSocketChannel implements CommunicationChannel {
+class WebSocketServerChannel implements ServerCommunicationChannel {
   /**
    * The socket being wrapped.
    */
@@ -54,12 +141,12 @@ class WebSocketChannel implements CommunicationChannel {
   /**
    * Initialize a newly create [WebSocket] wrapper to wrap the given [socket].
    */
-  WebSocketChannel(this.socket);
+  WebSocketServerChannel(this.socket);
 
   @override
   void listen(void onRequest(Request request), {void onError(), void onDone()}) {
-    socket.listen((data) =>
-        _readRequest(data, onRequest), onError: onError, onDone: onDone);
+    socket.listen((data) => _readRequest(data, onRequest), onError: onError,
+        onDone: onDone);
   }
 
   @override
@@ -68,11 +155,6 @@ class WebSocketChannel implements CommunicationChannel {
   }
 
   @override
-  void sendRequest(Request request) {
-    socket.add(jsonEncoder.convert(request.toJson()));
-  }
-
-  @override
   void sendResponse(Response response) {
     socket.add(jsonEncoder.convert(response.toJson()));
   }