Trigger re-analysis when a file changes on disk.

pkg/analysis_server/lib/src/context_directory_manager.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 context.directory.manager;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analysis_server/src/resource.dart';
@@ skipping 116 matching lines @@
         // TODO(paulberry): handle removing pubspec.yaml
         Source source = info.sources[event.path];
         if (source != null) {
           ChangeSet changeSet = new ChangeSet();
           changeSet.removedSource(source);
           applyChangesToContext(folder, changeSet);
           info.sources.remove(event.path);
         }
         break;
       case ChangeType.MODIFY:
-        // TODO(paulberry): handle modification events
+        Source source = info.sources[event.path];
+        if (source != null) {
+          ChangeSet changeSet = new ChangeSet();
+          // TODO(paulberry): technically we should skip calling changedSource()
+          // for files that currently have their contents overridden.  However,
+          // it's hard to figure out which files have their contents overridden
+          // (this info isn't exposed through the AnalysisContext interface),
+          // and besides, if we go ahead and call changedSource() we get the
+          // behavior we want (the context continues consulting the overridden
+          // file contents).
+          changeSet.changedSource(source);
+          applyChangesToContext(folder, changeSet);
+        }
         break;
     }
   }
 
   /**
    * Determine if the path from [folder] to [path] contains a 'packages'
    * directory.
    */
   bool _isInPackagesDir(String path, Folder folder) {
     String relativePath = resourceProvider.pathContext.relative(path, from: folder.path);
@@ skipping 46 matching lines @@
    * some of those files have been modified).  [changeSet] is the set of
    * changes that need to be applied to the context.
    */
   void applyChangesToContext(Folder contextFolder, ChangeSet changeSet);
 
   /**
    * Remove the context associated with the given [folder].
    */
   void removeContext(Folder folder);
 }