Add WorkItemBuilder to abstract WorkItem creation from the enqueuers.

pkg/compiler/lib/src/enqueue.dart

Index: pkg/compiler/lib/src/enqueue.dart
diff --git a/pkg/compiler/lib/src/enqueue.dart b/pkg/compiler/lib/src/enqueue.dart
index 6454c0de3918ed4cdb9833268f16199e2e8fa006..c54208c94861ea4928bc4e97f0aaf4f8f5fcb028 100644
--- a/pkg/compiler/lib/src/enqueue.dart
+++ b/pkg/compiler/lib/src/enqueue.dart
@@ -8,8 +8,7 @@ import 'dart:collection' show Queue;
 
 import 'cache_strategy.dart';
 import 'common/backend_api.dart' show Backend;
-import 'common/names.dart' show Identifiers;
-import 'common/resolution.dart' show Resolution, ResolutionWorkItem;
+import 'common/resolution.dart' show Resolution;
 import 'common/tasks.dart' show CompilerTask;
 import 'common/work.dart' show WorkItem;
 import 'common.dart';
@@ -19,7 +18,6 @@ import 'dart_types.dart' show DartType, InterfaceType;
 import 'elements/elements.dart'
     show
         AnalyzableElement,
-        AstElement,
         ClassElement,
         ConstructorElement,
         Element,
@@ -137,6 +135,7 @@ class ResolutionEnqueuer extends EnqueuerImpl {
   final EnqueuerStrategy strategy;
   final Set<ClassEntity> _recentClasses = new Setlet<ClassEntity>();
   final ResolutionWorldBuilderImpl _universe;
+  final WorkItemBuilder _workItemBuilder;
 
   bool queueIsClosed = false;
 
@@ -164,7 +163,8 @@ class ResolutionEnqueuer extends EnqueuerImpl {
         this._resolution = resolution,
         this.nativeEnqueuer = backend.nativeResolutionEnqueuer(),
         _universe = new ResolutionWorldBuilderImpl(
-            backend, resolution, cacheStrategy, const TypeMaskStrategy()) {
+            backend, resolution, cacheStrategy, const TypeMaskStrategy()),
+        _workItemBuilder = new ResolutionWorkItemBuilder(resolution) {
     _impactVisitor = new EnqueuerImplImpactVisitor(this);
   }
 
@@ -358,37 +358,32 @@ class ResolutionEnqueuer extends EnqueuerImpl {
 
   /// Returns `true` if [element] has been processed by the resolution enqueuer.
   // TODO(johnniwinther): Move this to the [OpenWorld]/[ResolutionWorldBuilder].
-  bool hasBeenProcessed(Element element) {
+  bool hasBeenProcessed(MemberElement element) {
     assert(invariant(element, element == element.analyzableElement.declaration,
         message: "Unexpected element $element"));
     return _processedEntities.contains(element);
   }
 
-  /// Registers [element] as processed by the resolution enqueuer. Used only for
+  /// Registers [entity] as processed by the resolution enqueuer. Used only for
   /// testing.
   void registerProcessedElementInternal(Entity entity) {
     _processedEntities.add(entity);
   }
 
-  /// Adds [element] to the work list if it has not already been processed.
-  ///
-  /// Invariant: [element] must be a declaration element.
-  void _addToWorkList(Element element) {
-    assert(invariant(element, element.isDeclaration));
-    if (element.isMalformed) return;
+  /// Create a [WorkItem] for [entity] and add it to the work list if it has not
+  /// already been processed.
+  void _addToWorkList(MemberEntity entity) {
+    if (hasBeenProcessed(entity)) return;
+    WorkItem workItem = _workItemBuilder.createWorkItem(entity);
+    if (workItem == null) return;
 
-    assert(invariant(element, element is AnalyzableElement,
-        message: 'Element $element is not analyzable.'));
-    if (hasBeenProcessed(element)) return;
     if (queueIsClosed) {
       throw new SpannableAssertionFailure(
-          element, "Resolution work list is closed. Trying to add $element.");
+          entity, "Resolution work list is closed. Trying to add $entity.");
     }
 
-    applyImpact(backend.registerUsedElement(element, forResolution: true));
-    _openWorld.registerUsedElement(element);
-
-    ResolutionWorkItem workItem = _resolution.createWorkItem(element);
+    applyImpact(backend.registerUsedElement(entity, forResolution: true));
+    _openWorld.registerUsedElement(entity);
     _queue.add(workItem);
   }
 
@@ -531,3 +526,26 @@ class _DeferredAction {
 
   _DeferredAction(this.element, this.action);
 }
+
+/// Interface for creating work items for enqueued member entities.
+abstract class WorkItemBuilder {
+  WorkItem createWorkItem(MemberEntity entity);

[Siggi Cherem (dart-lang), 2016/12/20 21:21:47]

eventually, should we turn this into just a typedef?

[Johnni Winther, 2016/12/21 10:19:37]

We could but it would make the descriptor of the builder function ugly (turning
ResolutionWorkItemBuilder and CodegenWorkItemBuilder item closures)

+}
+
+/// Builder that creates work item necessary for the resolution of a
+/// [MemberElement].
+class ResolutionWorkItemBuilder extends WorkItemBuilder {
+  final Resolution _resolution;
+
+  ResolutionWorkItemBuilder(this._resolution);
+
+  @override
+  WorkItem createWorkItem(MemberElement element) {
+    assert(invariant(element, element.isDeclaration));
+    if (element.isMalformed) return null;
+
+    assert(invariant(element, element is AnalyzableElement,
+        message: 'Element $element is not analyzable.'));
+    return _resolution.createWorkItem(element);
+  }
+}