Generative constructor factories for native objects

sdk/lib/_internal/lib/interceptors.dart

 // Copyright (c) 2012, 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 _interceptors;
 
 import 'dart:collection';
 import 'dart:_collection-dev' hide Symbol;
 import "dart:_collection-dev" as _symbol_dev show Symbol;
 import 'dart:_js_helper' show allMatchesInStringUnchecked,
@@ skipping 133 matching lines @@
 
 /**
  * If [JSInvocationMirror._invokeOn] is being used, this variable
  * contains a JavaScript array with the names of methods that are
  * intercepted.
  */
 var interceptedNames;
 
 
 /**
- * Data structure used to map a [Type] to the [Interceptor] for that type.  It
- * is JavaScript array of 2N entries of adjacent slots containing a [Type]
- * followed by an [Interceptor] class for the type.
+ * Data structure used to map a [Type] to the [Interceptor] and constructors for
+ * that type.  It is JavaScript array of 3N entries of adjacent slots containing
+ * a [Type], followed by an [Interceptor] class for the type, followed by a
+ * JavaScript object map for the constructors.
  *
  * The value of this variable is set by the compiler and contains only types
  * that are user extensions of native classes where the type occurs as a
  * constant in the program.
  */
 // TODO(sra): Mark this as initialized to a constant with unknown value.
 var mapTypeToInterceptor;
 
-findInterceptorConstructorForType(Type type) {
+int findIndexForWebComponentType(Type type) {
   JS_EFFECT((_){ mapTypeToInterceptor = _; });
   if (mapTypeToInterceptor == null) return null;
   List map = JS('JSFixedArray', '#', mapTypeToInterceptor);
-  for (int i = 0; i + 1 < map.length; i += 2) {
+  for (int i = 0; i + 1 < map.length; i += 3) {
     if (type == map[i]) {
-      return map[i + 1];
+      return i;
     }
   }
   return null;
 }
 
+findInterceptorConstructorForType(Type type) {
+  var index = findIndexForWebComponentType(type);
+  if (index == null) return null;
+  List map = JS('JSFixedArray', '#', mapTypeToInterceptor);
+  return mapTypeToInterceptor[index + 1];
+}
+
+/**
+ * Returns a JavaScript function that runs the constructor on its argument, or
+ * `null` if there is no such constructor.
+ *
+ * The returned function takes one argument, the web component object.
+ */
+findConstructorForWebComponentType(Type type, String name) {
+  var index = findIndexForWebComponentType(type);
+  if (index == null) return null;
+  List map = JS('JSFixedArray', '#', mapTypeToInterceptor);
+  var constructorMap = mapTypeToInterceptor[index + 2];
+  var constructorFn = JS('', '#[#]', constructorMap, name);
+  return constructorFn;
+}
+
 findInterceptorForType(Type type) {
   var constructor = findInterceptorConstructorForType(type);
   if (constructor == null) return null;
   return JS('', '#.prototype', constructor);
 }
 
 /**
  * The base interceptor class.
  *
  * The code `r.foo(a)` is compiled to `getInterceptor(r).foo$1(r, a)`.  The
@@ skipping 149 matching lines @@
 }
 
 
 /**
  * Interceptor for unclassified JavaScript objects, typically objects with a
  * non-trivial prototype chain.
  */
 class UnknownJavaScriptObject extends JavaScriptObject {
   const UnknownJavaScriptObject();
 }