Add DartWorkManager to manage Dart-specific results computation scheduling.

pkg/analyzer/lib/src/task/driver.dart

 // Copyright (c) 2015, 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 analyzer.src.task.driver;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisTask;
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/task/inputs.dart';
 import 'package:analyzer/src/task/manager.dart';
 import 'package:analyzer/task/model.dart';
 
 /**
  * An object that is used to cause analysis to be performed until all of the
  * required analysis information has been computed.
  */
 class AnalysisDriver {
   /**
    * The task manager used to figure out how to compute analysis results.
    */
   final TaskManager taskManager;
 
+//  /**
+//   * The list of [WorkManager] used to figure out which analysis results to
+//   * compute.
+//   */
+//  final List<WorkManager> workManagers;
+
   /**
    * The context in which analysis is to be performed.
    */
   final InternalAnalysisContext context;
 
   /**
    * The work order that was previously computed but that has not yet been
    * completed.
    */
   WorkOrder currentWorkOrder;
@@ skipping 424 matching lines @@
     TaskDescriptor descriptor = currentItem.descriptor;
     AnalysisTarget target = currentItem.target;
     for (WorkItem item in pendingItems) {
       if (item.descriptor == descriptor && item.target == target) {
         return true;
       }
     }
     return false;
   }
 }
+
+/**
+ * [AnalysisDriver] uses [WorkManager]s to select results to compute.
+ *
+ * They know specific of the targets and results they care about,
+ * so they can request analysis results in optimal order.
+ */
+abstract class WorkManager {
+  /**
+   * Return the next [TargetedResult] that this work manager wants to be
+   * computed, or `null` if this manager doesn't need any new results.
+   */
+  TargetedResult getNextResult();
+
+  /**
+   * Notifies the manager that the given [outputs] were produced for
+   * the given [target].
+   */
+  void resultsComputed(
+      AnalysisTarget target, Map<ResultDescriptor, dynamic> outputs);
+}