ES6 Unscopables

src/unscopables.h

Index: src/unscopables.h
diff --git a/src/unscopables.h b/src/unscopables.h
new file mode 100644
index 0000000000000000000000000000000000000000..f96d0212a5fe9ae7087350e25ded26c968903e16
--- /dev/null
+++ b/src/unscopables.h
@@ -0,0 +1,61 @@
+// Copyright 2014 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.
+
+#ifndef V8_UNSCOPABLES_H_
+#define V8_UNSCOPABLES_H_
+
+#include "src/isolate.h"
+#include "src/lookup.h"
+#include "src/objects.h"
+#include "src/prototype.h"
+
+namespace v8 {
+namespace internal {
+
+
+static bool BlockedByUnscopables(LookupIterator* it) {
+  Isolate* isolate = it->isolate();
+  Handle<Symbol> unscopables_symbol(
+      isolate->native_context()->unscopables_symbol(), isolate);
+
+  // TODO(arv): This should be GetNonHiddenHolder
+  Handle<JSReceiver> object;
+  if (it->state() == LookupIterator::JSPROXY) {

[arv (Not doing code reviews), 2014/07/23 23:10:40]

Toon, this is a bit ugly. I was considering adding a GetHolderOrJSProxy but
changing GetHolder to return a JSReceiver seems reasonable to me as well.

I'll look at the hidden prototype issue tomorrow.

+    object = it->GetJSProxy();
+  } else {
+    object = it->GetHolder();
+  }
+
+  if (!JSReceiver::HasOwnProperty(object, unscopables_symbol)) return false;
+  Handle<Object> unscopables;
+  MaybeHandle<Object> maybe_unscopables =
+      Object::GetProperty(object, unscopables_symbol);
+  if (!maybe_unscopables.ToHandle(&unscopables)) return false;
+  if (!unscopables->IsSpecObject()) return false;
+  return JSReceiver::HasOwnProperty(Handle<JSReceiver>::cast(unscopables),
+                                    it->name());
+}
+
+
+/**
+ * Lookups a property in an object environment, taking the unscopables into
+ * account. This is used For HasBinding and GetBindingValue spec algorithms for
+ * ObjectEnvironment.
+ */
+static PropertyAttributes UnscopableLookup(LookupIterator* it) {
+  PropertyAttributes attrs;
+  while ((attrs = JSReceiver::GetPropertyAttributes(it)) != ABSENT) {
+    if (!BlockedByUnscopables(it)) {
+      return attrs;
+    }
+    it->Next();
+  }
+
+  return ABSENT;
+}
+}
+
+}  // namespace v8::internal
+
+#endif  // V8_UNSCOPABLES_H_