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;
 }
 
 
-// ES5 section 15.2.3.4.
-function ObjectGetOwnPropertyNames(obj) {
-  if (!IS_SPEC_OBJECT(obj)) {
-    throw MakeTypeError("called_on_non_object", ["Object.getOwnPropertyNames"]);
+function FilterKeyNames(array, symbolsOnly) {

[rossberg, 2013/12/18 16:50:12]

Why can't we fold this into the loop at line 1108, and avoid duplicating the
work?

[arv (Not doing code reviews), 2013/12/18 18:07:12]

Done.

That would make more sense. And now I understand what you mean with your
previous comment.

[rossberg, 2013/12/19 10:28:04]

Yes, sorry if that was too cryptic.

+  var result = new InternalArray();
+  var j = 0;
+  for (var i = 0; i < array.length; i++) {
+    var key = array[i];
+    if (IS_SYMBOL(key)) {
+      if (symbolsOnly && !IS_PRIVATE(key)) {
+        result[j++] = key;
+      }
+    } else if (!symbolsOnly) {
+      result[j++] = key;
+    }
   }
-  // Special handling for proxies.
-  if (%IsJSProxy(obj)) {
-    var handler = %GetHandler(obj);
-    var names = CallTrap0(handler, "getOwnPropertyNames", UNDEFINED);
-    return ToNameArray(names, "getOwnPropertyNames", false);
-  }
+  result.length = j;
+  return result;
+}
 
+
+function ObjectGetOwnPropertyKeys(obj, symbolsOnly) {
   var nameArrays = new InternalArray();
+  var filter = symbolsOnly ?
+      PROPERTY_ATTRIBUTES_STRING | PROPERTY_ATTRIBUTES_PRIVATE_SYMBOL :
+      PROPERTY_ATTRIBUTES_SYMBOLIC;
 
   // Find all the indexed properties.
 
-  // Get the local element names.
-  var localElementNames = %GetLocalElementNames(obj);
-  for (var i = 0; i < localElementNames.length; ++i) {
-    localElementNames[i] = %_NumberToString(localElementNames[i]);
-  }
-  nameArrays.push(localElementNames);
+  // Only get the local element names if we want to include string keys.
+  if (!symbolsOnly) {
+    var localElementNames = %GetLocalElementNames(obj);
+    for (var i = 0; i < localElementNames.length; ++i) {
+      localElementNames[i] = %_NumberToString(localElementNames[i]);
+    }
+    nameArrays.push(localElementNames);
 
-  // Get names for indexed interceptor properties.
-  var interceptorInfo = %GetInterceptorInfo(obj);
-  if ((interceptorInfo & 1) != 0) {
-    var indexedInterceptorNames = %GetIndexedInterceptorElementNames(obj);
-    if (!IS_UNDEFINED(indexedInterceptorNames)) {
-      nameArrays.push(indexedInterceptorNames);
+    // Get names for indexed interceptor properties.
+    var interceptorInfo = %GetInterceptorInfo(obj);
+    if ((interceptorInfo & 1) != 0) {
+      var indexedInterceptorNames = %GetIndexedInterceptorElementNames(obj);
+      if (!IS_UNDEFINED(indexedInterceptorNames)) {
+        nameArrays.push(indexedInterceptorNames);
+      }
     }
   }
 
   // Find all the named properties.
 
   // Get the local property names.
-  nameArrays.push(%GetLocalPropertyNames(obj, false));
+  nameArrays.push(%GetLocalPropertyNames(obj, filter));
 
   // Get names for named interceptor properties if any.
   if ((interceptorInfo & 2) != 0) {
-    var namedInterceptorNames = %GetNamedInterceptorPropertyNames(obj);
+    var namedInterceptorNames =
+        %GetNamedInterceptorPropertyNames(obj);
     if (!IS_UNDEFINED(namedInterceptorNames)) {
-      nameArrays.push(namedInterceptorNames);
+      nameArrays.push(FilterKeyNames(namedInterceptorNames, symbolsOnly));
     }
   }
 
   var propertyNames =
       %Apply(InternalArray.prototype.concat,
              nameArrays[0], nameArrays, 1, nameArrays.length - 1);
 
   // Property names are expected to be unique strings,
   // but interceptors can interfere with that assumption.
   if (interceptorInfo != 0) {
-    var propertySet = { __proto__: null };
+    var seenKeys = { __proto__: null };
     var j = 0;
     for (var i = 0; i < propertyNames.length; ++i) {
-      if (IS_SYMBOL(propertyNames[i])) continue;
-      var name = ToString(propertyNames[i]);
-      // We need to check for the exact property value since for intrinsic
-      // properties like toString if(propertySet["toString"]) will always
-      // succeed.
-      if (propertySet[name] === true) {
-        continue;
+      var name = propertyNames[i];
+      if (!symbolsOnly) {
+        name = ToString(name);
       }
-      propertySet[name] = true;
+      if (seenKeys[name]) continue;
+      seenKeys[name] = true;
       propertyNames[j++] = name;
     }
     propertyNames.length = j;
   }
 
   return propertyNames;
 }
 
 
+// ES6 19.1.2.8
+function ObjectGetOwnPropertySymbols(obj) {
+  if (!IS_SPEC_OBJECT(obj)) {
+    throw MakeTypeError("called_on_non_object",
+                        ["Object.getOwnPropertySymbols"]);
+  }
+
+  // TODO(arv): Proxies use a shared trap for String and Symbol keys.
+
+  return ObjectGetOwnPropertyKeys(obj, true);
+}
+
+
+// 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);
+  }
+
+  return ObjectGetOwnPropertyKeys(obj, false);
+}
+
+
 // ES5 section 15.2.3.5.
 function ObjectCreate(proto, properties) {
   if (!IS_SPEC_OBJECT(proto) && proto !== null) {
     throw MakeTypeError("proto_object_or_null", [proto]);
   }
   var obj = { __proto__: proto };
   if (!IS_UNDEFINED(properties)) ObjectDefineProperties(obj, properties);
   return obj;
 }
 
@@ skipping 289 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.
     "is", ObjectIs,
     "isExtensible", ObjectIsExtensible,
     "isFrozen", ObjectIsFrozen,
     "isSealed", ObjectIsSealed,
     "preventExtensions", ObjectPreventExtension,
     "seal", ObjectSeal
+    // observe is added in object-observe.js.
   ));
 }
 
 SetUpObject();
 
 
 // ----------------------------------------------------------------------------
 // Boolean
 
 function BooleanConstructor(x) {
@@ skipping 406 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]();
   }
 }