Support refresh of individual analysis roots (issue 22254)

pkg/analysis_server/lib/src/context_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/analysis_server.dart';
@@ skipping 146 matching lines @@
       if (root.contains(path)) {
         return true;
       }
     }
     // no
     return false;
   }
 
   /**
    * Rebuild the set of contexts from scratch based on the data last sent to
-   * setRoots().
+   * setRoots(). Only contexts contained in the given list of analysis [roots]
+   * will be rebuilt, unless the list is `null`, in which case every context
+   * will be rebuilt.
    */
-  void refresh() {
+  void refresh(List<Resource> roots) {
     // Destroy old contexts
     List<Folder> contextFolders = _contexts.keys.toList();
-    contextFolders.forEach(_destroyContext);
+    if (roots == null) {
+      contextFolders.forEach(_destroyContext);
+    } else {
+      roots.forEach((Resource resource) {
+        contextFolders.forEach((Folder contextFolder) {
+          if (resource is Folder && resource.isOrContains(contextFolder.path)) {
+            _destroyContext(contextFolder);
+          }
+        });
+      });
+    }
 
     // Rebuild contexts based on the data last sent to setRoots().
     setRoots(includedPaths, excludedPaths, packageRoots);
   }
 
   /**
    * Remove the context associated with the given [folder].
    */
   void removeContext(Folder folder);
 
@@ skipping 568 matching lines @@
     return excludes(resource.path);
   }
 
   /**
    * Returns `true` if [path] is the pubspec file of this context.
    */
   bool isPubspec(String path) {
     return path == pubspecPath;
   }
 }