Make AssistContributor asynchronous.

pkg/analysis_server/lib/src/services/correction/assist.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 services.correction.assist;
 
 import 'package:analysis_server/plugin/edit/assist/assist_core.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/source.dart';
+import 'dart:async';
 
 /**
  * Compute and return the assists available at the given selection (described by
  * the [offset] and [length]) in the given [source]. The source was analyzed in
- * the given [context]. The [plugin] is used to get the list of assist
+ * the given [analysisContext]. The [plugin] is used to get the list of assist
  * contributors.
  */
-List<Assist> computeAssists(ServerPlugin plugin, AnalysisContext context,
-    Source source, int offset, int length) {
+Future<List<Assist>> computeAssists(
+    ServerPlugin plugin,
+    AnalysisContext analysisContext,
+    Source source,
+    int offset,
+    int length) async {
   List<Assist> assists = <Assist>[];
   List<AssistContributor> contributors = plugin.assistContributors;
+  AssistContextImpl assistContext =
+      new AssistContextImpl(analysisContext, source, offset, length);
   for (AssistContributor contributor in contributors) {
     try {
       List<Assist> contributedAssists =
-          contributor.computeAssists(context, source, offset, length);
+          await contributor.computeAssists(assistContext);
       if (contributedAssists != null) {
         assists.addAll(contributedAssists);
       }
     } catch (exception, stackTrace) {
       AnalysisEngine.instance.logger.logError(
           'Exception from assist contributor: ${contributor.runtimeType}',
           new CaughtException(exception, stackTrace));
     }
   }
   assists.sort(Assist.SORT_BY_RELEVANCE);
   return assists;
 }
 
 /**
+ * The implementation of [AssistContext].
+ */
+class AssistContextImpl implements AssistContext {
+  @override
+  final AnalysisContext analysisContext;
+
+  @override
+  final Source source;
+
+  @override
+  final int selectionOffset;
+
+  @override
+  final int selectionLength;
+
+  AssistContextImpl(this.analysisContext, this.source, this.selectionOffset,
+      this.selectionLength);
+}
+
+/**
  * An enumeration of possible assist kinds.
  */
 class DartAssistKind {
   static const ADD_PART_DIRECTIVE =
       const AssistKind('ADD_PART_DIRECTIVE', 30, "Add 'part' directive");
   static const ADD_TYPE_ANNOTATION =
       const AssistKind('ADD_TYPE_ANNOTATION', 30, "Add type annotation");
   static const ASSIGN_TO_LOCAL_VARIABLE = const AssistKind(
       'ASSIGN_TO_LOCAL_VARIABLE', 30, "Assign value to new local variable");
   static const CONVERT_DOCUMENTATION_INTO_BLOCK = const AssistKind(
@@ skipping 56 matching lines @@
       const AssistKind('SURROUND_WITH_FOR_IN', 30, "Surround with 'for-in'");
   static const SURROUND_WITH_IF =
       const AssistKind('SURROUND_WITH_IF', 30, "Surround with 'if'");
   static const SURROUND_WITH_TRY_CATCH = const AssistKind(
       'SURROUND_WITH_TRY_CATCH', 30, "Surround with 'try-catch'");
   static const SURROUND_WITH_TRY_FINALLY = const AssistKind(
       'SURROUND_WITH_TRY_FINALLY', 30, "Surround with 'try-finally'");
   static const SURROUND_WITH_WHILE =
       const AssistKind('SURROUND_WITH_WHILE', 30, "Surround with 'while'");
 }