Refactor superclass change.

dart/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.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.
 
 part of dart2js.js_emitter;
 
 
 class OldEmitter implements Emitter {
   final Compiler compiler;
   final CodeEmitterTask task;
@@ skipping 1426 matching lines @@
       mainBuffer..add(
           'self.${deferredInitializers} = self.${deferredInitializers} || '
           'Object.create(null);$n');
     }
 
     // Using a named function here produces easier to read stack traces in
     // Chrome/V8.
     mainBuffer.add('(function(${namer.currentIsolate})$_{\n');
     if (compiler.hasIncrementalSupport) {
       mainBuffer.add(
-          '(this.\$dart_unsafe_eval ='
-          ' this.\$dart_unsafe_eval || Object.create(null))'
-          '.patch = function(a) { eval(a) }$N');
+          'this.\$dart_unsafe_eval ='
+          ' this.\$dart_unsafe_eval || Object.create(null)$N');
+      mainBuffer.add(
+          'this.\$dart_unsafe_eval.patch = function(a) { eval(a) }$N');
+      String schemaChange =
+          jsAst.prettyPrint(buildSchemaChangeFunction(), compiler).getText();
+      mainBuffer.add(
+          'this.\$dart_unsafe_eval.schemaChange$_=$_$schemaChange$N');
     }
     if (isProgramSplit) {
       /// We collect all the global state of the, so it can be passed to the
       /// initializer of deferred files.
       mainBuffer.add('var ${globalsHolder}$_=${_}Object.create(null)$N');
     }
     mainBuffer.add('function dart()$_{$n'
         '${_}${_}this.x$_=${_}0$N'
         '${_}${_}delete this.x$N'
         '}$n');
@@ skipping 181 matching lines @@
           generateSourceMapTag(compiler.sourceMapUri, compiler.outputUri));
       assembledCode = mainBuffer.getText();
     }
 
     compiler.outputProvider('', 'js')
         ..add(assembledCode)
         ..close();
     compiler.assembledCode = assembledCode;
   }
 
+  /// Used by incremental compilation to patch up the prototype of
+  /// [oldConstructor] for use as prototype of [newConstructor].
+  jsAst.Fun buildSchemaChangeFunction() {
+    return js('''
+function(newConstructor, oldConstructor, superclass) {
+  // Invariant: newConstructor.prototype has no interesting properties besides
+  // generated accessors. These are copied to oldPrototype which will be
+  // updated by other incremental changes.
+  if (superclass != null) {
+    this.inheritFrom(newConstructor, superclass);
+  }
+  var oldPrototype = oldConstructor.prototype;
+  var newPrototype = newConstructor.prototype;
+  var hasOwnProperty = Object.prototype.hasOwnProperty;
+  for (var property in newPrototype) {
+    if (hasOwnProperty.call(newPrototype, property)) {
+      // Copy generated accessors.
+      oldPrototype[property] = newPrototype[property];
+    }
+  }
+  oldPrototype.__proto__ = newConstructor.prototype.__proto__;
+  oldPrototype.constructor = newConstructor;
+  newConstructor.prototype = oldPrototype;
+  return newConstructor;
+}''');
+  }
+
   /// Returns a map from OutputUnit to a hash of its content. The hash uniquely
   /// identifies the code of the output-unit. It does not include
   /// boilerplate JS code, like the sourcemap directives or the hash
   /// itself.
   Map<OutputUnit, String> emitDeferredOutputUnits() {
     if (!compiler.deferredLoadTask.isProgramSplit) return const {};
 
     Map<OutputUnit, CodeBuffer> outputBuffers =
         new Map<OutputUnit, CodeBuffer>();
 
@@ skipping 318 matching lines @@
     for (Element element in compiler.enqueuer.codegen.newlyEnqueuedElements) {
       if (element.isInstanceMember) {
         cachedClassBuilders.remove(element.enclosingClass);
 
         nativeEmitter.cachedBuilders.remove(element.enclosingClass);
 
       }
     }
   }
 }