Make AnalysisSErver APIs to access unit/node/element asynchronous.

pkg/analysis_server/lib/src/analysis_server.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 analysis.server;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:core';
 import 'dart:io' as io;
@@ skipping 688 matching lines @@
         Source source = sources.first;
         return new ContextSourcePair(context, source);
       }
     }
     // file-based source
     Source fileSource = file.createSource();
     return new ContextSourcePair(null, fileSource);
   }
 
   /**
-   * Return the [Element] at the given [offset] of the given [file], or `null`
-   * if there is no node at the [offset] or the node does not have an element.
+   * Return the [Future] that completes with the [Element] at the given

[Paul Berry, 2016/11/22 18:06:18]

s/Return the [Future]/Return a [Future]/

("Return the Future..." implies that there is some specific preexisting future
which the caller knows about that should be returned)

A similar comment fix needs to be made to getNodeAtOffset and
getResolvedCompilationUnit.

[scheglov, 2016/11/22 18:45:47]

Done.

+   * [offset] of the given [file], or with `null` if there is no node at the
+   * [offset] or the node does not have an element.
    */
-  Element getElementAtOffset(String file, int offset) {
-    AstNode node = getNodeAtOffset(file, offset);
+  Future<Element> getElementAtOffset(String file, int offset) async {
+    AstNode node = await getNodeAtOffset(file, offset);
     return getElementOfNode(node);
   }
 
   /**
    * Return the [Element] of the given [node], or `null` if [node] is `null` or
    * does not have an element.
    */
   Element getElementOfNode(AstNode node) {
     if (node == null) {
       return null;
@@ skipping 34 matching lines @@
     if (context == null) {
       return null;
     }
     if (!context.exists(source)) {
       return null;
     }
     return context.getErrors(source);
   }
 
   /**
-   * Return the resolved [AstNode]s at the given [offset] of the given [file],
-   * or `null` if there is no node as the [offset].
+   * Return the [Future] that completes with the resolved [AstNode] at the
+   * given [offset] of the given [file], or with `null` if there is no node as
+   * the [offset].
    */
-  AstNode getNodeAtOffset(String file, int offset) {
-    CompilationUnit unit = getResolvedCompilationUnit(file);
+  Future<AstNode> getNodeAtOffset(String file, int offset) async {
+    CompilationUnit unit = await getResolvedCompilationUnit(file);
     if (unit != null) {
       return new NodeLocator(offset).searchWithin(unit);
     }
     return null;
   }
 
   /**
-   * Return the resolved [CompilationUnit] for the Dart file with the given
-   * [path], or `null` if the file is not a Dart file or cannot be resolved.
+   * Return the [Future] that completes with the resolved [CompilationUnit] for
+   * the Dart file with the given [path], or with `null` if the file is not a
+   * Dart file or cannot be resolved.
    */
-  CompilationUnit getResolvedCompilationUnit(String path) {
+  Future<CompilationUnit> getResolvedCompilationUnit(String path) async {
     ContextSourcePair contextSource = getContextSourcePair(path);
     AnalysisContext context = contextSource.context;
     if (context == null) {
       return null;
     }
     return runWithActiveContext(context, () {
       Source unitSource = contextSource.source;
       List<Source> librarySources = context.getLibrariesContaining(unitSource);
       for (Source librarySource in librarySources) {
         return context.resolveCompilationUnit2(unitSource, librarySource);
@@ skipping 1243 matching lines @@
   /**
    * The [PerformanceTag] for time spent in server request handlers.
    */
   static PerformanceTag serverRequests = new PerformanceTag('serverRequests');
 
   /**
    * The [PerformanceTag] for time spent in split store microtasks.
    */
   static PerformanceTag splitStore = new PerformanceTag('splitStore');
 }