Implement Object.defineProperty for proxies.

src/v8natives.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 336 matching lines @@
   }
   if (IsAccessorDescriptor(desc)) {
     obj.get = desc.getGet();
     obj.set = desc.getSet();
   }
   obj.enumerable = desc.isEnumerable();
   obj.configurable = desc.isConfigurable();
   return obj;
 }
 
+// Harmony Proxies
+function FromGenericPropertyDescriptor(desc) {
+  if (IS_UNDEFINED(desc)) return desc;
+  var obj = new $Object();
+  if (desc.hasValue_) obj.value = desc.getValue();

[Kevin Millikin (Chromium), 2011/07/07 08:12:02]

It's not obvious why you use the property hasValue_ in the test and the accessor
getValue() in the assignment.

[rossberg, 2011/07/07 09:19:32]

True. I copied from pre-existing functions. I fixed those, too.

+  if (desc.hasWritable_) obj.writable = desc.isWritable();
+  if (desc.hasGetter_) obj.get = desc.getGet();
+  if (desc.hasSetter_) obj.set = desc.getSet();
+  if (desc.hasEnumerable_) obj.enumerable = desc.isEnumerable();
+  if (desc.hasConfigurable_) obj.configurable = desc.isConfigurable();
+  return obj;
+}
+
 // ES5 8.10.5.
 function ToPropertyDescriptor(obj) {
   if (!IS_SPEC_OBJECT(obj)) {
     throw MakeTypeError("property_desc_object", [obj]);
   }
   var desc = new PropertyDescriptor();
 
   if ("enumerable" in obj) {
     desc.setEnumerable(ToBoolean(obj.enumerable));
   }
@@ skipping 242 matching lines @@
   // If p is not a property on obj undefined is returned.
   var props = %GetOwnProperty(ToObject(obj), ToString(p));
 
   // A false value here means that access checks failed.
   if (props === false) return void 0;
 
   return ConvertDescriptorArrayToDescriptor(props);
 }
 
 
+// Harmony proxies.
+function DefineProxyProperty(obj, p, attributes, should_throw) {
+  var handler = %GetHandler(obj);
+  var defineProperty = handler.defineProperty;
+  if (IS_UNDEFINED(defineProperty)) {
+    throw MakeTypeError("handler_trap_missing", [handler, "defineProperty"]);
+  }
+  var result = defineProperty.call(handler, p, attributes);
+  if (!ToBoolean(result)) {
+    if (should_throw) {
+      throw MakeTypeError("handler_failed", [handler, "defineProperty"]);
+    } else {
+      return false;
+    }
+  }
+  return true;
+}
+
+
 // ES5 8.12.9.
 function DefineOwnProperty(obj, p, desc, should_throw) {
+  if (%IsJSProxy(obj)) {
+    var attributes = FromGenericPropertyDescriptor(desc);
+    return DefineProxyProperty(obj, p, attributes, should_throw);
+  }
+
   var current_or_access = %GetOwnProperty(ToObject(obj), ToString(p));
   // A false value here means that access checks failed.
   if (current_or_access === false) return void 0;
 
   var current = ConvertDescriptorArrayToDescriptor(current_or_access);
   var extensible = %IsExtensible(ToObject(obj));
 
   // Error handling according to spec.
   // Step 3
   if (IS_UNDEFINED(current) && !extensible) {
@@ skipping 262 matching lines @@
   return obj;
 }
 
 
 // ES5 section 15.2.3.6.
 function ObjectDefineProperty(obj, p, attributes) {
   if (!IS_SPEC_OBJECT(obj)) {
     throw MakeTypeError("obj_ctor_property_non_object", ["defineProperty"]);
   }
   var name = ToString(p);
-  var desc = ToPropertyDescriptor(attributes);
-  DefineOwnProperty(obj, name, desc, true);
+  if (%IsJSProxy(obj)) {
+    // Clone the attributes object for protection.
+    // TODO(rossberg): not spec'ed yet, so not sure if this should involve
+    // non-own properties as it does (or non-enumerable ones, as it doesn't?).
+    var attributesClone = {}
+    for (var a in attributes) {
+      attributesClone[a] = attributes[a];
+    }
+    DefineProxyProperty(obj, name, attributesClone, true);
+    // The following would implement the spec as in the current proposal,
+    // but after recent comments on es-discuss, is most likely obsolete.
+    /*
+    var defineObj = FromGenericPropertyDescriptor(desc);
+    var names = ObjectGetOwnPropertyNames(attributes);
+    var standardNames =
+      {value: 0, writable: 0, get: 0, set: 0, enumerable: 0, configurable: 0};
+    for (var i = 0; i < names.length; i++) {
+      var N = names[i];
+      if (!(%HasLocalProperty(standardNames, N))) {
+        var attr = GetOwnProperty(attributes, N);
+        DefineOwnProperty(descObj, N, attr, true);
+      }
+    }
+    // This is really confusing the types, but it is what the proxies spec
+    // currently requires:
+    desc = descObj;
+    */
+  } else {
+    var desc = ToPropertyDescriptor(attributes);
+    DefineOwnProperty(obj, name, desc, true);
+  }
   return obj;
 }
 
 
 // ES5 section 15.2.3.7.
 function ObjectDefineProperties(obj, properties) {
   if (!IS_SPEC_OBJECT(obj))
     throw MakeTypeError("obj_ctor_property_non_object", ["defineProperties"]);
   var props = ToObject(properties);
   var key_values = [];
@@ skipping 476 matching lines @@
 // ----------------------------------------------------------------------------
 
 function SetupFunction() {
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "bind", FunctionBind,
     "toString", FunctionToString
   ));
 }
 
 SetupFunction();