Split implementation of KernelToElementMapImpl

pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart

 // Copyright (c) 2017, 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 dart2js.kernel.backend_strategy;
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../backend_strategy.dart';
 import '../closure.dart';
 import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/tasks.dart';
 import '../compiler.dart';
 import '../elements/entities.dart';
 import '../elements/entity_utils.dart' as utils;
 import '../enqueue.dart';
 import '../io/source_information.dart';
 import '../js/js_source_mapping.dart';
 import '../js_backend/backend.dart';
 import '../js_backend/native_data.dart';
 import '../js_emitter/sorter.dart';
 import '../js_model/closure.dart';
+import '../js_model/js_strategy.dart';
 import '../js_model/locals.dart';
 import '../kernel/element_map.dart';
 import '../kernel/element_map_impl.dart';
 import '../native/behavior.dart';
 import '../options.dart';
 import '../ssa/builder_kernel.dart';
 import '../ssa/nodes.dart';
 import '../ssa/ssa.dart';
 import '../ssa/types.dart';
 import '../types/types.dart';
 import '../universe/selector.dart';
 import '../universe/world_builder.dart';
 import '../universe/world_impact.dart';
 import '../world.dart';
 import 'element_map_impl.dart';
 import 'kernel_strategy.dart';
 
+/// If `true` the [JsStrategy] is used as the backend strategy.
+bool useJsStrategyForTesting = false;
+
 /// A backend strategy based on Kernel IR nodes.
 abstract class KernelBackendStrategy implements BackendStrategy {
   KernelToElementMapForBuilding get elementMap;
   GlobalLocalsMap get globalLocalsMapForTesting;
+
+  factory KernelBackendStrategy(Compiler compiler) {
+    return useJsStrategyForTesting
+        ? new JsBackendStrategy(compiler)
+        : new KernelBackendStrategyImpl(compiler);
+  }
 }
 
 /// Backend strategy that uses the kernel elements as the backend model.
 // TODO(redemption): Replace this with a strategy based on the J-element
 // model.
 class KernelBackendStrategyImpl implements KernelBackendStrategy {
   final Compiler _compiler;
   Sorter _sorter;
   ClosureConversionTask _closureDataLookup;
   final GlobalLocalsMap _globalLocalsMap = new GlobalLocalsMap();
 
   KernelBackendStrategyImpl(this._compiler);
 
   KernelToElementMapForBuilding get elementMap {
     KernelFrontEndStrategy frontendStrategy = _compiler.frontendStrategy;
-    return frontendStrategy.elementMap;
+    KernelToElementMapImpl elementMap = frontendStrategy.elementMap;
+    return elementMap;
   }
 
   GlobalLocalsMap get globalLocalsMapForTesting => _globalLocalsMap;
 
   @override
   ClosedWorldRefiner createClosedWorldRefiner(
       covariant KernelClosedWorld closedWorld) {
     return closedWorld;
   }
 
@@ skipping 190 matching lines @@
     return _closedWorld.commonMasks.dynamicType;
   }
 
   @override
   TypeMask getReturnTypeOf(FunctionEntity function) {
     return _closedWorld.commonMasks.dynamicType;
   }
 }
 
 class KernelSorter implements Sorter {
-  final KernelToElementMapImpl elementMap;
+  final KernelToElementMapForBuilding elementMap;
 
   KernelSorter(this.elementMap);
 
   int _compareLibraries(LibraryEntity a, LibraryEntity b) {
     return utils.compareLibrariesUris(a.canonicalUri, b.canonicalUri);
   }
 
   int _compareNodes(
       Entity entity1, ir.TreeNode node1, Entity entity2, ir.TreeNode node2) {
     ir.Location location1 = node1.location;
@@ skipping 25 matching lines @@
   Iterable<ClassEntity> sortClasses(Iterable<ClassEntity> classes) {
     return classes.toList()
       ..sort((ClassEntity a, ClassEntity b) {
         int r = _compareLibraries(a.library, b.library);
         if (r != 0) return r;
         return _compareNodes(
             a, elementMap.getClassNode(a), b, elementMap.getClassNode(b));
       });
   }
 }