Rework "analysis.updateContent" analysis server request.

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 'package:analyzer/file_system/file_system.dart';
@@ skipping 465 matching lines @@
       AnalysisContext analysisContext = getAnalysisContext(file);
       // TODO(paulberry): handle the case where a file is referred to by more
       // than one context (e.g package A depends on package B using a local
       // path, user has both packages open for editing in separate contexts,
       // and user modifies a file in package B).
       if (analysisContext != null) {
         Source source = getSource(file);
         if (change.offset == null) {
           analysisContext.setContents(source, change.content);
         } else {
-          analysisContext.setChangedContents(source, change.content,
-              change.offset, change.oldLength, change.newLength);
+          // TODO(paulberry): an error should be generated if source is not
+          // currently in the content cache.
+          TimestampedData<String> oldContents = analysisContext.getContents(
+              source);
+          int offsetEnd = change.offset + change.oldLength;
+          String newContents = oldContents.data.substring(0, change.offset) +
+              change.content + oldContents.data.substring(offsetEnd);
+          analysisContext.setChangedContents(source, newContents, change.offset,
+              change.oldLength, change.content.length);
         }
         schedulePerformAnalysisOperation(analysisContext);
       }
     });
   }
 
   /**
    * Implementation for `analysis.setSubscriptions`.
    */
   void setAnalysisSubscriptions(Map<AnalysisService, Set<String>> subscriptions) {
@@ skipping 317 matching lines @@
 /**
  * An enumeration of the services provided by the server domain.
  */
 class ServerService extends Enum2<ServerService> {
   static const ServerService STATUS = const ServerService('STATUS', 0);
 
   static const List<ServerService> VALUES = const [STATUS];
 
   const ServerService(String name, int ordinal) : super(name, ordinal);
 }