Refactor superclass change.

dart/pkg/dart2js_incremental/lib/library_updater.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 dart2js_incremental.library_updater;
 
 import 'dart:async' show
     Future;
 
 import 'dart:convert' show
@@ skipping 463 matching lines @@
     Set newClasses =
         new Set.from(compiler.codegenWorld.directlyInstantiatedClasses);
     newClasses.removeAll(existingClasses);
 
     List<jsAst.Statement> inherits = <jsAst.Statement>[];
 
     for (ClassElementX cls in newClasses) {
       jsAst.Node classAccess = namer.elementAccess(cls);
       String name = namer.getNameOfClass(cls);
 
-      var descriptor = js('Object.create(null)');
-
-      jsAst.Statement defineClass = js.statement(
-          r'''
-# = (new Function(
-    "$collectedClasses", "$desc",
-    self.$dart_unsafe_eval.defineClass(#, #) +"\n;return " + #))({#: #})
-''',
-          [classAccess,
-           js.string(name), js.stringArray(computeFields(cls)),
-           js.string(name),
-           js.string(name), descriptor]);
-
-      updates.add(defineClass);
+      updates.add(
+          js.statement(
+              r'# = #', [classAccess, invokeDefineClass(cls)]));
 
       ClassElement superclass = cls.superclass;
       if (superclass != null) {
         jsAst.Node superAccess = namer.elementAccess(superclass);
         inherits.add(
             js.statement(
                 r'self.$dart_unsafe_eval.inheritFrom(#, #)',
                 [classAccess, superAccess]));
       }
     }
 
+    // Call inheritFrom after all classes have been created. This way we don't
+    // need to sort the classes by having superclasses defined before their
+    // subclasses.
     updates.addAll(inherits);
 
     for (ClassElementX cls in changedClasses) {
       ClassElement superclass = cls.superclass;
-      if (superclass != null) {
-        jsAst.Node classAccess = namer.elementAccess(cls);
-        jsAst.Node superAccess = namer.elementAccess(superclass);
-        updates.add(
-            js.statement(
-                r'#.prototype.__proto__ = #.prototype',
-                [classAccess, superAccess]));
-        updates.add(
-            js.statement(
-                r'#.prototype.constructor = #',
-                [classAccess, classAccess]));
-      }
+      jsAst.Node superAccess =
+          superclass == null ? js('null') : namer.elementAccess(superclass);
+      jsAst.Node classAccess = namer.elementAccess(cls);
+      updates.add(
+          js.statement(
+              r'# = self.$dart_unsafe_eval.schemaChange(#, #, #)',
+              [classAccess, invokeDefineClass(cls), classAccess, superAccess]));
     }
 
     for (RemovedFunctionUpdate update in removals) {
       update.writeUpdateJsOn(updates);
     }
     for (Element element in compiler.enqueuer.codegen.newlyEnqueuedElements) {
       if (!element.isField) {
         updates.add(computeMemberUpdateJs(element));
       }
     }
 
     if (updates.length == 1) {
       return prettyPrintJs(updates.single);
     } else {
       return prettyPrintJs(js.statement('{#}', [updates]));
     }
   }
 
+  jsAst.Expression invokeDefineClass(ClassElementX cls) {
+    String name = namer.getNameOfClass(cls);
+    var descriptor = js('Object.create(null)');
+    return js(
+        r'''
+(new Function(
+    "$collectedClasses", "$desc",
+    self.$dart_unsafe_eval.defineClass(#, #) +"\n;return " + #))({#: #})''',
+        [js.string(name), js.stringArray(computeFields(cls)),
+         js.string(name),
+         js.string(name), descriptor]);
+  }
+
   jsAst.Node computeMemberUpdateJs(Element element) {
     MemberInfo info = emitter.oldEmitter.containerBuilder
         .analyzeMemberMethod(element);
     if (info == null) {
       compiler.internalError(element, '${element.runtimeType}');
     }
     String name = info.name;
     jsAst.Node function = info.code;
     List<jsAst.Statement> statements = <jsAst.Statement>[];
     if (element.isInstanceMember) {
@@ skipping 457 matching lines @@
 
   ClassEmitter get classEmitter => backend.emitter.oldEmitter.classEmitter;
 
   List<String> computeFields(ClassElement cls) {
     // TODO(ahe): Rewrite for new emitter.
     ClassBuilder builder = new ClassBuilder(cls, namer);
     classEmitter.emitFields(cls, builder, "");
     return builder.fields;
   }
 }