ES6 Unscopables

src/unscopables.h

+// 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/objects.h"
+#include "src/prototype.h"
+
+namespace v8 {
+namespace internal {
+
+
+/**
+ * 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(Isolate* isolate,
+                                           Handle<JSReceiver> object,
+                                           Handle<String> name,
+                                           Handle<JSReceiver>* holder,
+                                           bool* ok) {
+  Handle<Symbol> unscopables_symbol(
+      isolate->native_context()->unscopables_symbol(), isolate);
+  *ok = true;
+
+  for (PrototypeIterator iter(isolate, object,
+                              PrototypeIterator::START_AT_RECEIVER);
+       !iter.IsAtEnd(); iter.Advance()) {
+    Handle<JSReceiver> object =
+        Handle<JSReceiver>::cast(PrototypeIterator::GetCurrent(iter));
+
+    PropertyAttributes name_attrs =
+        JSReceiver::GetOwnPropertyAttributes(object, name);
+    if (name_attrs != ABSENT) {
+      bool has_unscopables =
+          JSReceiver::HasOwnProperty(object, unscopables_symbol);
+      bool blocked = false;
+      if (has_unscopables) {
+        MaybeHandle<Object> maybe_unscopables_object =
+            Object::GetProperty(object, unscopables_symbol);
+        Handle<Object> unscopables_object;
+        if (!maybe_unscopables_object.ToHandle(&unscopables_object)) {
+          ASSERT(isolate->has_pending_exception());
+          *ok = false;
+          return ABSENT;
+        }
+        if (unscopables_object->IsSpecObject()) {
+          blocked = JSReceiver::HasOwnProperty(
+              Handle<JSReceiver>::cast(unscopables_object), name);
+        }
+      }
+
+      if (!blocked) {
+        *holder = object;
+        return name_attrs;
+      }
+    }
+  }
+  return ABSENT;
+}
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_UNSCOPABLES_H_