[proxies] Implement [[Enumerate]] and [[OwnPropertyKeys]]

src/js/proxy.js

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 134 matching lines @@
     var name = names[i]
     if (IS_SYMBOL(name)) continue
     var desc = this.getOwnPropertyDescriptor(TO_STRING(name))
     if (!IS_UNDEFINED(desc) && desc.enumerable) {
       enumerableNames[count++] = names[i]
     }
   }
   return enumerableNames
 }
 
-function DerivedEnumerateTrap() {
-  var names = this.getPropertyNames()
-  var enumerableNames = []
-  for (var i = 0, count = 0; i < names.length; ++i) {
-    var name = names[i]
-    if (IS_SYMBOL(name)) continue
-    var desc = this.getPropertyDescriptor(TO_STRING(name))
-    if (!IS_UNDEFINED(desc)) {
-      if (!desc.configurable) {
-        throw MakeTypeError(kProxyPropNotConfigurable,
-                            this, name, "getPropertyDescriptor")
-      }
-      if (desc.enumerable) enumerableNames[count++] = names[i]
+// Implements part of ES6 9.5.11 Proxy.[[Enumerate]]:
+// Call the trap, which should return an iterator, exhaust the iterator,
+// and return an array containing the values.
+function ProxyEnumerate(trap, handler, target) {
+  // 7. Let trapResult be ? Call(trap, handler, «target»).
+  var trap_result = %_Call(trap, handler, target);
+  // 8. If Type(trapResult) is not Object, throw a TypeError exception.
+  if (!IS_SPEC_OBJECT(trap_result)) {
+    throw MakeTypeError(kProxyHandlerReturned, handler, "non-Object",
+                        "enumerate");
+  }
+  // 9. Return trapResult.
+  var result = [];
+  for (var it = trap_result.next(); !it.done; it = trap_result.next()) {
+    var key = it.value;
+    // Not yet spec'ed as of 2015-11-25, but will be spec'ed soon:
+    // If the iterator returns a non-string value, throw a TypeError.
+    if (!IS_STRING(key)) {
+      throw MakeTypeError(kProxyHandlerReturned, handler, "non-String",
+                          "enumerate-iterator");
     }
+    result.push(key);
   }
-  return enumerableNames
-}
-
-function ProxyEnumerate(proxy) {
-  var handler = %GetHandler(proxy)
-  if (IS_UNDEFINED(handler.enumerate)) {
-    return %Apply(DerivedEnumerateTrap, handler, [], 0, 0)
-  } else {
-    return ToNameArray(handler.enumerate(), "enumerate", false)
-  }
+  return result;
 }
 
 //-------------------------------------------------------------------
 %SetCode(GlobalProxy, ProxyCreate);
 
 //Set up non-enumerable properties of the Proxy object.
 utils.InstallFunctions(GlobalProxy, DONT_ENUM, [
   "createFunction", ProxyCreateFunction
 ]);
 
 // -------------------------------------------------------------------
 // Exports
 
 utils.Export(function(to) {
   to.ProxyDelegateCallAndConstruct = DelegateCallAndConstruct;
   to.ProxyDerivedHasOwnTrap = DerivedHasOwnTrap;
   to.ProxyDerivedKeysTrap = DerivedKeysTrap;
 });
 
 %InstallToContext([
   "derived_get_trap", DerivedGetTrap,
   "derived_has_trap", DerivedHasTrap,
   "derived_set_trap", DerivedSetTrap,
   "proxy_enumerate", ProxyEnumerate,
 ]);
 
 })