ES6: Add Object.getOwnPropertySymbols

src/v8natives.js

 // Copyright 2012 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 1020 matching lines @@
     }
     array[index] = s;
     ++realLength;
     names[s] = 0;
   }
   array.length = realLength;
   return array;
 }
 
 
+function GetSymbolsInArray(propertyKeys) {

[rossberg, 2013/12/10 10:39:53]

Nit: perhaps call this FilterPublicSymbols?

[arv (Not doing code reviews), 2013/12/11 00:16:26]

Done.

+  var symbols = new InternalArray();
+  var j = 0;
+  for (var i = 0; i < propertyKeys.length; i++) {
+    if (IS_SYMBOL(propertyKeys[i]) && !%SymbolIsPrivate(propertyKeys[i])) {

[rossberg, 2013/12/10 10:39:53]

It might make sense to introduce an IS_PRIVATE macro for the latter.

[arv (Not doing code reviews), 2013/12/11 00:16:26]

Done.

+      symbols[j++] = propertyKeys[i];
+    }
+  }
+  return symbols;
+}
+
+
+// ES6 19.1.2.8
+function ObjectGetOwnPropertySymbols(obj) {
+  if (!IS_SPEC_OBJECT(obj)) {
+    throw MakeTypeError("called_on_non_object",
+                        ["Object.getOwnPropertySymbols"]);
+  }
+
+  // FIXME: Proxies use a shared trap for String and Symbol keys.

[rossberg, 2013/12/10 10:39:53]

Please use TODO(arv); same below

[arv (Not doing code reviews), 2013/12/11 00:16:26]

Done.

+
+  var nameArrays = new InternalArray();
+
+  // Find all the indexed properties.
+
+  // Get names for indexed interceptor properties.
+  var interceptorInfo = %GetInterceptorInfo(obj);
+
+  // Find all the named properties.
+
+  // Get the local property symbols.
+  // FIXME: Have the runtime do the filtering.

[rossberg, 2013/12/10 10:39:53]

Yeah, I would very much prefer to have this implemented efficiently right away,
at least for ordinary properties (for interceptor properties it matters less).
Just turn the Boolean flag into a three-way flag.

+  nameArrays.push(GetSymbolsInArray(%GetLocalPropertyNames(obj, true)));
+
+  // Get names for named interceptor properties if any.
+  if ((interceptorInfo & 2) != 0) {
+    // FIXME: Have the runtime do the filtering.
+    var namedInterceptorNames = %GetNamedInterceptorPropertyNames(obj);
+    if (!IS_UNDEFINED(namedInterceptorNames)) {
+      nameArrays.push(GetSymbolsInArray(namedInterceptorSymbols));
+    }
+  }
+
+  var propertySymbols =
+      %Apply(InternalArray.prototype.concat,
+             nameArrays[0], nameArrays, 1, nameArrays.length - 1);
+
+  // Property names are expected to be unique,
+  // but interceptors can interfere with that assumption.
+  if (interceptorInfo != 0) {
+    var propertySet = { __proto__: null };
+    var j = 0;
+    for (var i = 0; i < propertySymbols.length; ++i) {
+      var symbol = propertySymbols[i];
+      if (!IS_SYMBOL(symbol) || %SymbolIsPrivate(symbol)) continue;
+
+      // We need to check for the exact property value since for intrinsic
+      // properties like toString if(propertySet["toString"]) will always
+      // succeed.
+      if (propertySet[symbol] === true) {

[rossberg, 2013/12/10 10:39:53]

Could combine this with the previous if.

[arv (Not doing code reviews), 2013/12/11 00:16:26]

I also don't think this comment is correct. propertySet is an object with a null
[[Prototype]] so there is no toString on it. I'll update the original case too.

+        continue;
+      }
+      propertySet[symbol] = true;
+      propertySymbols[j++] = symbol;
+    }
+    propertySymbols.length = j;
+  }
+
+  return propertySymbols;
+}
+
 // ES5 section 15.2.3.4.
 function ObjectGetOwnPropertyNames(obj) {
   if (!IS_SPEC_OBJECT(obj)) {
     throw MakeTypeError("called_on_non_object", ["Object.getOwnPropertyNames"]);
   }
   // Special handling for proxies.
   if (%IsJSProxy(obj)) {
     var handler = %GetHandler(obj);
     var names = CallTrap0(handler, "getOwnPropertyNames", UNDEFINED);
     return ToNameArray(names, "getOwnPropertyNames", false);
@@ skipping 362 matching lines @@
   // Set up non-enumerable functions in the Object object.
   InstallFunctions($Object, DONT_ENUM, $Array(
     "keys", ObjectKeys,
     "create", ObjectCreate,
     "defineProperty", ObjectDefineProperty,
     "defineProperties", ObjectDefineProperties,
     "freeze", ObjectFreeze,
     "getPrototypeOf", ObjectGetPrototypeOf,
     "getOwnPropertyDescriptor", ObjectGetOwnPropertyDescriptor,
     "getOwnPropertyNames", ObjectGetOwnPropertyNames,
+    // getOwnPropertySymbols is added in symbol.js

[rossberg, 2013/12/10 10:39:53]

Good to have that comment here. While you're at it, can you add the same for
.observe?

[arv (Not doing code reviews), 2013/12/11 00:16:26]

Done.

     "is", ObjectIs,
     "isExtensible", ObjectIsExtensible,
     "isFrozen", ObjectIsFrozen,
     "isSealed", ObjectIsSealed,
     "preventExtensions", ObjectPreventExtension,
     "seal", ObjectSeal
   ));
 }
 
 SetUpObject();
@@ skipping 412 matching lines @@
 // Eventually, we should move to a real event queue that allows to maintain
 // relative ordering of different kinds of tasks.
 
 RunMicrotasks.runners = new InternalArray;
 
 function RunMicrotasks() {
   while (%SetMicrotaskPending(false)) {
     for (var i in RunMicrotasks.runners) RunMicrotasks.runners[i]();
   }
 }