Extension point for WorkManagerFactory(s).

pkg/analyzer/lib/src/plugin/engine_plugin.dart

Index: pkg/analyzer/lib/src/plugin/engine_plugin.dart
diff --git a/pkg/analyzer/lib/src/plugin/engine_plugin.dart b/pkg/analyzer/lib/src/plugin/engine_plugin.dart
index eb516de99ac6be40f590558b467719c7cecf2e14..3b80617ace6039562ff21e2bb7758602a6bc5168 100644
--- a/pkg/analyzer/lib/src/plugin/engine_plugin.dart
+++ b/pkg/analyzer/lib/src/plugin/engine_plugin.dart
@@ -5,9 +5,13 @@
 library analyzer.src.plugin.engine_plugin;
 
 import 'package:analyzer/plugin/task.dart';
+import 'package:analyzer/src/generated/engine.dart'
+    show InternalAnalysisContext;
 import 'package:analyzer/src/task/dart.dart';
+import 'package:analyzer/src/task/dart_work_manager.dart';
 import 'package:analyzer/src/task/general.dart';
 import 'package:analyzer/src/task/html.dart';
+import 'package:analyzer/src/task/html_work_manager.dart';
 import 'package:analyzer/task/model.dart';
 import 'package:plugin/plugin.dart';
 
@@ -23,6 +27,13 @@ class EnginePlugin implements Plugin {
   static const String TASK_EXTENSION_POINT = 'task';
 
   /**
+   * The simple identifier of the extension point that allows plugins to
+   * register new work manager factories with the analysis engine.
+   */
+  static const String WORK_MANAGER_FACTORY_EXTENSION_POINT =
+      'workManagerFactory';
+
+  /**
    * The unique identifier of this plugin.
    */
   static const String UNIQUE_IDENTIFIER = 'analysis_engine.core';
@@ -34,6 +45,12 @@ class EnginePlugin implements Plugin {
   ExtensionPoint taskExtensionPoint;
 
   /**
+   * The extension point that allows plugins to register new work manager
+   * factories with the analysis engine.
+   */
+  ExtensionPoint workManagerFactoryExtensionPoint;
+
+  /**
    * Initialize a newly created plugin.
    */
   EnginePlugin();
@@ -46,14 +63,29 @@ class EnginePlugin implements Plugin {
   @override
   String get uniqueIdentifier => UNIQUE_IDENTIFIER;
 
+  /**
+   * Return a list containing all of the work manager factories that were
+   * contributed.
+   */
+  List<WorkManagerFactory> get workManagerFactories =>
+      workManagerFactoryExtensionPoint.extensions;
+
   @override
   void registerExtensionPoints(RegisterExtensionPoint registerExtensionPoint) {
     taskExtensionPoint =
         registerExtensionPoint(TASK_EXTENSION_POINT, _validateTaskExtension);
+    workManagerFactoryExtensionPoint = registerExtensionPoint(
+        WORK_MANAGER_FACTORY_EXTENSION_POINT,
+        _validateWorkManagerFactoryExtension);
   }
 
   @override
   void registerExtensions(RegisterExtension registerExtension) {
+    _registerTaskExtensions(registerExtension);
+    _registerWorkManagerFactoryExtensions(registerExtension);
+  }
+
+  void _registerTaskExtensions(RegisterExtension registerExtension) {
     String taskId = TASK_EXTENSION_POINT_ID;
     //
     // Register general tasks.
@@ -97,6 +129,15 @@ class EnginePlugin implements Plugin {
     registerExtension(taskId, ParseHtmlTask.DESCRIPTOR);
   }
 
+  void _registerWorkManagerFactoryExtensions(
+      RegisterExtension registerExtension) {
+    String taskId = WORK_MANAGER_EXTENSION_POINT_ID;
+    registerExtension(taskId,
+        (InternalAnalysisContext context) => new DartWorkManager(context));
+    registerExtension(taskId,
+        (InternalAnalysisContext context) => new HtmlWorkManager(context));
+  }
+
   /**
    * Validate the given extension by throwing an [ExtensionError] if it is not a
    * valid domain.
@@ -107,4 +148,16 @@ class EnginePlugin implements Plugin {
       throw new ExtensionError('Extensions to $id must be a TaskDescriptor');
     }
   }
+
+  /**
+   * Validate the given extension by throwing an [ExtensionError] if it is not a
+   * valid domain.
+   */
+  void _validateWorkManagerFactoryExtension(Object extension) {
+    if (extension is! WorkManagerFactory) {
+      String id = taskExtensionPoint.uniqueIdentifier;
+      throw new ExtensionError(
+          'Extensions to $id must be a WorkManagerFactory');
+    }
+  }
 }