Support for dart:typed_data

tool/input_sdk/private/rtti.dart

 // Copyright (c) 2015, 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.
 
 /// This library defines the association between runtime objects and
 /// runtime types.
 part of dart._runtime;
 
 ///
 /// Runtime type information.  This module defines the mapping from
@@ skipping 75 matching lines @@
     case "symbol":
       return Symbol;
   }
   // Undefined is handled above. For historical reasons,
   // typeof null == "object" in JS.
   if ($obj === null) return $Null;
   return null;
 })()''');
 
 runtimeType(obj) => JS('', '''(() => {
+  // Lookup primitive (int/double/string)
   let result = $checkPrimitiveType($obj);
   if (result !== null) return result;
-  return $obj.runtimeType;
+
+  // Lookup recorded type
+  result = $obj.runtimeType;
+  if (result) return result;
+
+  return $_nonPrimitiveRuntimeType(obj);
 })()''');
 
 getFunctionType(obj) => JS('', '''(() => {
   // TODO(vsm): Encode this properly on the function for Dart-generated code.
   let args = Array($obj.length).fill($dynamicR);
   return $definiteFunctionType($bottom, args);
 })()''');
 
 ///
 /// Returns the runtime type of obj. This is the same as `obj.realRuntimeType`
 /// but will not call an overridden getter.
 ///
 /// Currently this will return null for non-Dart objects.
 ///
 realRuntimeType(obj) => JS('', '''(() => {
+  // Lookup primitive type
   let result = $checkPrimitiveType($obj);
   if (result !== null) return result;
+
+  return $_nonPrimitiveRuntimeType(obj);
+})()''');
+
+_nonPrimitiveRuntimeType(obj) => JS('', '''(() => {
+  // Lookup recorded *real* type (not user definable runtimeType)
   // TODO(vsm): Should we treat Dart and JS objects differently here?
   // E.g., we can check if obj instanceof core.Object to differentiate.
-  result = $obj[$_runtimeType];
+  let result = $obj[$_runtimeType];
   if (result) return result;
+
+  // Lookup extension type
+  result = $obj[$_extensionType];
+  if (result) return result;
+
+  // Fallback on constructor for class types
   result = $obj.constructor;
   if (result == Function) {
     // An undecorated Function should have come from
     // JavaScript.  Treat as untyped.
     return $jsobject;
   }
   return result;
 })()''');
 
 LazyTagged(infoFn) => JS('', '''(() => {
@@ skipping 18 matching lines @@
 tagMemoized(value, compute) => JS('', '''(() => {
   let cache = null;
   function getter() {
     if ($compute == null) return cache;
     cache = $compute();
     $compute = null;
     return cache;
   }
   $tagComputed($value, getter);
 })()''');