Maintain referential integrity of proxy instances in dart:js

sdk/lib/js/dart2js/js_dart2js.dart

Index: sdk/lib/js/dart2js/js_dart2js.dart
diff --git a/sdk/lib/js/dart2js/js_dart2js.dart b/sdk/lib/js/dart2js/js_dart2js.dart
index 64b4af0b4771972ac4ac9b773480ece956d914b8..4ee6c2966bfb6fe963b677bfd0556c9a772711f8 100644
--- a/sdk/lib/js/dart2js/js_dart2js.dart
+++ b/sdk/lib/js/dart2js/js_dart2js.dart
@@ -166,6 +166,14 @@ abstract class Serializable<T> {
   T toJs();
 }
 
+// property added to a Dart object referencing its JS-side DartObject proxy
+const _DART_OBJECT_PROPERTY_NAME = r'_$dart_dartObject';
+const _DART_CLOSURE_PROPERTY_NAME = r'_$dart_dartClosure';
+
+// property added to a JS object referencing its Dart-side JsObject proxy
+const _JS_OBJECT_PROPERTY_NAME = r'_$dart_jsObject';
+const _JS_FUNCTION_PROPERTY_NAME = r'$dart_jsFunction';
+
 dynamic _convertToJS(dynamic o) {
   if (o == null) {
     return null;
@@ -178,10 +186,12 @@ dynamic _convertToJS(dynamic o) {
   } else if (o is Function) {
     return _convertToJS(new Callback(o));
   } else {
-    return JS('=Object', 'new DartProxy(#)', o);
+    return JS('=Object', 'new DartObject(#)', o);
   }
 }
 
+// converts a Dart object to a reference to a native JS object
+// which might be a DartObject JS->Dart proxy
 dynamic _convertToDart(dynamic o) {
   if (JS('bool', '# == null', o)) {
     return null;
@@ -190,10 +200,22 @@ dynamic _convertToDart(dynamic o) {
       JS('bool', 'typeof # == "boolean" || # instanceof Boolean', o, o)) {
     return o;
   } else if (JS('bool', '# instanceof Function', o)) {
-    return new JsFunction._fromJs(JS('=Object', '#', o));
-  } else if (JS('bool', '# instanceof DartProxy', o)) {
+    return _getDartProxy(o, _DART_CLOSURE_PROPERTY_NAME,
+        (o) => JsFunction._fromJs(o));

[alexandre.ardhuin, 2013/10/07 19:41:30]

"new" is missing.

[justinfagnani, 2013/10/07 20:17:51]

Done.

+  } else if (JS('bool', '# instanceof DartObject', o)) {
     return JS('var', '#.o', o);
   } else {
-    return new JsObject._fromJs(JS('=Object', '#', o));
+    return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
+        (o) => JsObject._fromJs(o));

[alexandre.ardhuin, 2013/10/07 19:41:30]

"new" is missing.

[justinfagnani, 2013/10/07 20:17:51]

Done.

   }
-}
+}
+
+dynamic _getDartProxy(o, String propertyName, createProxy(o)) {
+    var dartProxy = JS('', '#[#]', o, propertyName);

[alexandre.ardhuin, 2013/10/07 19:41:30]

Indentation size.

[justinfagnani, 2013/10/07 20:17:51]

Done.

+    if (dartProxy == null) {
+      dartProxy = createProxy(JS('=Object', '#', o));
+      JS('void', 'Object.defineProperty(#, #, { value: #})', o, propertyName,
+          dartProxy);
+    }
+    return dartProxy;
+}