Use InternalArray in Object.getOwnPropertyNames() implementation

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 996 matching lines @@
   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", void 0);
     return ToStringArray(names, "getOwnPropertyNames");
   }
 
+  var nameArrays = new InternalArray();
+
   // Find all the indexed properties.
 
   // Get the local element names.
-  var propertyNames = %GetLocalElementNames(obj);
-  for (var i = 0; i < propertyNames.length; ++i) {
-    propertyNames[i] = %_NumberToString(propertyNames[i]);
+  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 (indexedInterceptorNames) {
-      propertyNames = propertyNames.concat(indexedInterceptorNames);
+    var indexedInterceptorNames = %GetIndexedInterceptorElementNames(obj);
+    if (!IS_UNDEFINED(indexedInterceptorNames)) {
+      nameArrays.push(indexedInterceptorNames);
     }
   }
 
   // Find all the named properties.
 
   // Get the local property names.
-  propertyNames = propertyNames.concat(%GetLocalPropertyNames(obj));
+  nameArrays.push(%GetLocalPropertyNames(obj));
 
   // Get names for named interceptor properties if any.
   if ((interceptorInfo & 2) != 0) {
-    var namedInterceptorNames =
-        %GetNamedInterceptorPropertyNames(obj);
-    if (namedInterceptorNames) {
-      propertyNames = propertyNames.concat(namedInterceptorNames);
+    var namedInterceptorNames = %GetNamedInterceptorPropertyNames(obj);
+    if (!IS_UNDEFINED(namedInterceptorNames)) {
+      nameArrays.push(namedInterceptorNames);
     }
   }
 
+  var propertyNames = %Apply(InternalArray.prototype.concat,
+                             new InternalArray(),
+                             nameArrays,
+                             0,
+                             nameArrays.length);
+
   // Property names are expected to be unique strings,
   // but interceptors can interfere with that assumption.
   if (interceptorInfo != 0) {
     var propertySet = { __proto__: null };
     var j = 0;
     for (var i = 0; i < propertyNames.length; ++i) {
       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;
       }
       propertySet[name] = true;
       propertyNames[j++] = name;
     }
     propertyNames.length = j;
   }
 
-  return propertyNames;
+  var result = new $Array();
+  %MoveArrayContents(propertyNames, result);

[Michael Starzinger, 2013/03/12 12:09:06]

This call to MoveArrayContents has become obsolete. Just return propertyNames
here.

[adamk, 2013/03/12 18:25:19]

Done.

+  return result;
 }
 
 
 // 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 = new $Object();
   obj.__proto__ = proto;
@@ skipping 645 matching lines @@
 
 function SetUpFunction() {
   %CheckIsBootstrapping();
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "bind", FunctionBind,
     "toString", FunctionToString
   ));
 }
 
 SetUpFunction();