ES6 Unscopables

src/contexts.cc

 // Copyright 2011 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.
 
 #include "src/v8.h"
 
 #include "src/bootstrapper.h"
 #include "src/debug.h"
 #include "src/scopeinfo.h"
 
@@ skipping 53 matching lines @@
 JSObject* Context::global_proxy() {
   return native_context()->global_proxy_object();
 }
 
 
 void Context::set_global_proxy(JSObject* object) {
   native_context()->set_global_proxy_object(object);
 }
 
 
+/**
+ * Lookups a property in an object environment, taking the unscopables into
+ * account. This is used For HasBinding spec algorithms for ObjectEnvironment.
+ */
+static Maybe<PropertyAttributes> UnscopableLookup(LookupIterator* it) {
+  Isolate* isolate = it->isolate();
+
+  Maybe<PropertyAttributes> attrs = JSReceiver::GetPropertyAttributes(it);
+  DCHECK(attrs.has_value || isolate->has_pending_exception());
+  if (!attrs.has_value || attrs.value == ABSENT) return attrs;
+
+  Handle<Symbol> unscopables_symbol(
+      isolate->native_context()->unscopables_symbol(), isolate);
+  Handle<Object> receiver = it->GetReceiver();
+  Handle<Object> unscopables;
+  MaybeHandle<Object> maybe_unscopables =
+      Object::GetProperty(receiver, unscopables_symbol);
+  if (!maybe_unscopables.ToHandle(&unscopables)) {
+    return Maybe<PropertyAttributes>();
+  }
+  if (!unscopables->IsSpecObject()) return attrs;
+  Maybe<bool> blacklist = JSReceiver::HasProperty(
+      Handle<JSReceiver>::cast(unscopables), it->name());
+  if (!blacklist.has_value) {
+    DCHECK(isolate->has_pending_exception());
+    return Maybe<PropertyAttributes>();
+  }
+  if (blacklist.value) return maybe(ABSENT);
+  return attrs;
+}
+
+
 Handle<Object> Context::Lookup(Handle<String> name,
                                ContextLookupFlags flags,
                                int* index,
                                PropertyAttributes* attributes,
                                BindingFlags* binding_flags) {
   Isolate* isolate = GetIsolate();
   Handle<Context> context(this, isolate);
 
   bool follow_context_chain = (flags & FOLLOW_CONTEXT_CHAIN) != 0;
   *index = -1;
@@ skipping 19 matching lines @@
         (context->IsFunctionContext() && context->has_extension())) {
       Handle<JSReceiver> object(
           JSReceiver::cast(context->extension()), isolate);
       // Context extension objects needs to behave as if they have no
       // prototype.  So even if we want to follow prototype chains, we need
       // to only do a local lookup for context extension objects.
       Maybe<PropertyAttributes> maybe;
       if ((flags & FOLLOW_PROTOTYPE_CHAIN) == 0 ||
           object->IsJSContextExtensionObject()) {
         maybe = JSReceiver::GetOwnPropertyAttributes(object, name);
+      } else if (FLAG_harmony_unscopables && context->IsWithContext()) {
+        LookupIterator it(object, name);
+        maybe = UnscopableLookup(&it);
       } else {
         maybe = JSReceiver::GetPropertyAttributes(object, name);
       }
+
       if (!maybe.has_value) return Handle<Object>();
       DCHECK(!isolate->has_pending_exception());
       *attributes = maybe.value;
 
       if (maybe.value != ABSENT) {
         if (FLAG_trace_contexts) {
           PrintF("=> found property in context object %p\n",
                  reinterpret_cast<void*>(*object));
         }
         return object;
@@ skipping 247 matching lines @@
 bool Context::IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object) {
   // During bootstrapping we allow all objects to pass as global
   // objects. This is necessary to fix circular dependencies.
   return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
       isolate->bootstrapper()->IsActive() ||
       object->IsGlobalObject();
 }
 #endif
 
 } }  // namespace v8::internal