Add support for adding/removing pubspec.yaml files.

pkg/analysis_server/lib/src/resource.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 resource;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:io' as io;
 
@@ skipping 228 matching lines @@
     _provider._pathToResource.forEach((resourcePath, resource) {
       if (posix.dirname(resourcePath) == path) {
         children.add(resource);
       }
     });
     return children;
   }
 
   @override
   Stream<WatchEvent> get changes {
-    if (_provider._pathToWatcher.containsKey(path)) {
-      // Two clients watching the same path is not yet supported.
-      // TODO(paulberry): add support for this if needed.
-      throw new StateError('Path "$path" is already being watched for changes');
+    StreamController<WatchEvent> streamController = new StreamController<WatchEvent>();
+    if (!_provider._pathToWatchers.containsKey(path)) {
+      _provider._pathToWatchers[path] = <StreamController<WatchEvent>>[];
     }
-    StreamController<WatchEvent> streamController = new StreamController<WatchEvent>();
-    _provider._pathToWatcher[path] = streamController;
+    _provider._pathToWatchers[path].add(streamController);
     streamController.done.then((_) {
-      _provider._pathToWatcher.remove(path);
+      _provider._pathToWatchers[path].remove(streamController);
+      if (_provider._pathToWatchers[path].isEmpty) {
+        _provider._pathToWatchers.remove(path);
+      }
     });
     return streamController.stream;
   }
 }
 
 
 /**
  * An in-memory implementation of [ResourceProvider].
  * Use `/` as a path separator.
  */
 class MemoryResourceProvider implements ResourceProvider {
   final Map<String, _MemoryResource> _pathToResource =
       new HashMap<String, _MemoryResource>();
   final Map<String, String> _pathToContent = new HashMap<String, String>();
   final Map<String, int> _pathToTimestamp = new HashMap<String, int>();
-  final Map<String, StreamController<WatchEvent>> _pathToWatcher =
-      new HashMap<String, StreamController<WatchEvent>>();
+  final Map<String, List<StreamController<WatchEvent>>> _pathToWatchers =
+      new HashMap<String, List<StreamController<WatchEvent>>>();
   int nextStamp = 0;
 
   @override
   Resource getResource(String path) {
     path = posix.normalize(path);
     Resource resource = _pathToResource[path];
     if (resource == null) {
       resource = new _MemoryFile(this, path);
     }
     return resource;
@@ skipping 33 matching lines @@
     newFolder(posix.dirname(path));
     _MemoryFile file = new _MemoryFile(this, path);
     _pathToResource[path] = file;
     _pathToContent[path] = content;
     _pathToTimestamp[path] = nextStamp++;
     _notifyWatchers(path, ChangeType.ADD);
     return file;
   }
 
   void _notifyWatchers(String path, ChangeType changeType) {
-    _pathToWatcher.forEach((String watcherPath, StreamController<WatchEvent> streamController) {
+    _pathToWatchers.forEach((String watcherPath, List<StreamController<WatchEvent>> streamControllers) {
       if (posix.isWithin(watcherPath, path)) {
-        streamController.add(new WatchEvent(changeType, path));
+        for (StreamController<WatchEvent> streamController in streamControllers) {
+          streamController.add(new WatchEvent(changeType, path));
+        }
       }
     });
   }
 
   void modifyFile(String path, String content) {
     _checkFileAtPath(path);
     _pathToContent[path] = content;
     _pathToTimestamp[path] = nextStamp++;
     _notifyWatchers(path, ChangeType.MODIFY);
   }
@@ skipping 108 matching lines @@
       return new _PhysicalFolder(directory);
     } else {
       io.File file = new io.File(path);
       return new _PhysicalFile(file);
     }
   }
 
   @override
   Context get pathContext => io.Platform.isWindows ? windows : posix;
 }