Split channels library.

pkg/analysis_server/lib/src/channel/channel.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library channel;
+
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:analysis_server/src/protocol.dart';
+
+/**
+ * The abstract class [ClientCommunicationChannel] defines the behavior of
+ * objects that allow a client to send [Request]s to an [AnalysisServer] and to
+ * receive both [Response]s and [Notification]s.
+ */
+abstract class ClientCommunicationChannel {
+  /**
+   * The stream of notifications from the server.
+   */
+  Stream<Notification> notificationStream;
+
+  /**
+   * The stream of responses from the server.
+   */
+  Stream<Response> responseStream;
+
+  /**
+   * Send the given [request] to the server
+   * and return a future with the associated [Response].
+   */
+  Future<Response> sendRequest(Request request);
+
+  /**
+   * Close the channel to the server. Once called, all future communication
+   * with the server via [sendRequest] will silently be ignored.
+   */
+  Future close();
+}
+
+/**
+ * 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
+   * the socket, invoke the [onError] function. If the socket is closed by the
+   * client, invoke the [onDone] function.
+   * Only one listener is allowed per channel.
+   */
+  void listen(void onRequest(Request request), {Function onError, void onDone()});
+
+  /**
+   * Send the given [notification] to the client.
+   */
+  void sendNotification(Notification notification);
+
+  /**
+   * Send the given [response] to the client.
+   */
+  void sendResponse(Response response);
+
+  /**
+   * Close the communication channel.
+   */
+  void close();
+}
+
+/**
+ * Instances of the class [JsonStreamDecoder] convert JSON strings to JSON
+ * maps.
+ */
+class JsonStreamDecoder extends Converter<String, Map> {
+  @override
+  Map convert(String text) => JSON.decode(text);
+
+  @override
+  ChunkedConversionSink startChunkedConversion(Sink sink) =>
+      new ChannelChunkSink<String, Map>(this, sink);
+}
+
+/**
+ * Instances of the class [ResponseConverter] convert JSON maps to [Response]s.
+ */
+class ResponseConverter extends Converter<Map, Response> {
+  @override
+  Response convert(Map json) => new Response.fromJson(json);
+
+  @override
+  ChunkedConversionSink startChunkedConversion(Sink sink) =>
+      new ChannelChunkSink<Map, Response>(this, sink);
+}
+
+/**
+ * Instances of the class [NotificationConverter] convert JSON maps to
+ * [Notification]s.
+ */
+class NotificationConverter extends Converter<Map, Notification> {
+  @override
+  Notification convert(Map json) => new Notification.fromJson(json);
+
+  @override
+  ChunkedConversionSink startChunkedConversion(Sink sink) =>
+      new ChannelChunkSink<Map, Notification>(this, sink);
+}
+
+/**
+ * Instances of the class [ChannelChunkSink] uses a [Converter] to translate
+ * chunks.
+ */
+class ChannelChunkSink<S, T> extends ChunkedConversionSink<S> {
+  /**
+   * The converter used to translate chunks.
+   */
+  final Converter<S, T> converter;
+
+  /**
+   * The sink to which the converted chunks are added.
+   */
+  final Sink sink;
+
+  /**
+   * A flag indicating whether the sink has been closed.
+   */
+  bool closed = false;
+
+  /**
+   * Initialize a newly create sink to use the given [converter] to convert
+   * chunks before adding them to the given [sink].
+   */
+  ChannelChunkSink(this.converter, this.sink);
+
+  @override
+  void add(S chunk) {
+    if (!closed) {
+      T convertedChunk = converter.convert(chunk);
+      if (convertedChunk != null) {
+        sink.add(convertedChunk);
+      }
+    }
+  }
+
+  @override
+  void close() {
+    closed = true;
+    sink.close();
+  }
+}