Use interceptors to handle runtime types.

dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.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.
 
 part of js_backend;
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
@@ skipping 3141 matching lines @@
     }
     if (hasBool) {
       block.statements.add(buildInterceptorCheck(backend.jsBoolClass));
     }
     // TODO(ahe): It might be faster to check for Array before
     // function and bool.
     if (hasArray) {
       block.statements.add(buildInterceptorCheck(backend.jsArrayClass));
     }
 
+    // Recognize JavaScript functions that correspond to Dart constructors
+    // (generated by defineClass that adds the property 'builtin$cls').
+    // TODO(ahe): Either integrate this with native dispatchProperty, or use a
+    // mixin approach in defineClass.
+    block.statements.add(
+        js.if_(r'typeof receiver == "function" && "builtin$cls" in receiver',
+               buildReturnInterceptor(backend.jsRuntimeType)));
+
+    // Recognize JavaScript object literals that are used to encode function
+    // types. These objects are generated by
+    // [TypeRepresentationGenerator.visitFunctionType] and always have the

[ngeoffray, 2013/09/10 10:42:26]

missing something after 'and'.

+    // "func" property (namer.functionTypeTag()).
+    // TODO(ahe): This should be a real Dart object and we should be able to
+    // remove this test (so I'm keeping the redundant "object" test).
+    block.statements.add(
+        js.if_(r'typeof receiver == "object"'
+               // JavaScript object literals have Object as constructor.
+               ' && receiver.constructor === Object'
+               ' && "${namer.functionTypeTag()}" in receiver',
+               buildReturnInterceptor(backend.jsFunctionType)));
+
     if (hasNative) {
       block.statements.add(
-          js.if_(
-              js('(typeof receiver) != "object"'),
-              js.return_(js('receiver'))));
+          js.if_('typeof receiver != "object"', js.return_('receiver')));
 
-      // if (receiver instanceof $.Object) return receiver;
-      // return $.getNativeInterceptor(receiver);
       block.statements.add(
           js.if_(js('receiver instanceof #',
                     js(namer.isolateAccess(compiler.objectClass))),
-                 js.return_(js('receiver'))));
+                 js.return_('receiver')));
       block.statements.add(
           js.return_(
               js(namer.isolateAccess(backend.getNativeInterceptorMethod))(
                   ['receiver'])));
 
     } else {
       ClassElement jsUnknown = backend.jsUnknownJavaScriptObjectClass;
       if (compiler.codegenWorld.instantiatedClasses.contains(jsUnknown)) {
         block.statements.add(
             js.if_(js('!(receiver instanceof #)',
@@ skipping 1017 matching lines @@
 
 const String HOOKS_API_USAGE = """
 // The code supports the following hooks:
 // dartPrint(message)   - if this function is defined it is called
 //                        instead of the Dart [print] method.
 // dartMainRunner(main) - if this function is defined, the Dart [main]
 //                        method will not be invoked directly.
 //                        Instead, a closure that will invoke [main] is
 //                        passed to [dartMainRunner].
 """;