[modules] Implement @@iterator on namespace objects.

src/bootstrapper.cc

 // 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.
 
 #include "src/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/base/ieee754.h"
 #include "src/code-stubs.h"
@@ skipping 2133 matching lines @@
         global, "Set", JS_SET_TYPE, JSSet::kSize,
         isolate->initial_object_prototype(), Builtins::kIllegal);
     InstallWithIntrinsicDefaultProto(isolate, js_set_fun,
                                      Context::JS_SET_FUN_INDEX);
   }
 
   {  // -- J S M o d u l e N a m e s p a c e
     Handle<Map> map =
         factory->NewMap(JS_MODULE_NAMESPACE_TYPE, JSModuleNamespace::kSize);
     Map::SetPrototype(map, isolate->factory()->null_value());
+    Map::EnsureDescriptorSlack(map, 2);
     native_context()->set_js_module_namespace_map(*map);
 
-    // Install @@toStringTag.
-    PropertyAttributes attribs =
-        static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY);
-    DataConstantDescriptor d(factory->to_string_tag_symbol(),
-                             factory->NewStringFromAsciiChecked("Module"),
-                             attribs);
-    Map::EnsureDescriptorSlack(map, 1);
-    map->AppendDescriptor(&d);
+    {  // Install @@toStringTag.
+      PropertyAttributes attribs =
+          static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY);
+      DataConstantDescriptor d(factory->to_string_tag_symbol(),
+                               factory->NewStringFromAsciiChecked("Module"),
+                               attribs);
+      map->AppendDescriptor(&d);
+    }
 
-    // TODO(neis): Implement and install @@iterator.
+    {  // Install @@iterator.
+      Handle<JSFunction> iterator = SimpleCreateFunction(
+          isolate, factory->NewStringFromAsciiChecked("[Symbol.iterator]"),
+          Builtins::kModuleNamespaceIterator, 0, true);
+      iterator->shared()->set_native(true);
+      // TODO(neis): Is this really supposed to be writable?

[Benedikt Meurer, 2016/10/12 03:24:05]

You can remove this TODO. All the @@iterator properties are writable (for
whatever reason).

[adamk, 2016/10/12 16:21:47]

The Module case is somewhat special, as the spec goes to some length to try to
avoid modifications to the Module object; that's what this TODO is about.

+      DataConstantDescriptor d(factory->iterator_symbol(), iterator, DONT_ENUM);
+      map->AppendDescriptor(&d);
+    }
   }
 
   {  // -- I t e r a t o r R e s u l t
     Handle<Map> map =
         factory->NewMap(JS_OBJECT_TYPE, JSIteratorResult::kSize);
     Map::SetPrototype(map, isolate->initial_object_prototype());
     Map::EnsureDescriptorSlack(map, 2);
 
     {  // value
       DataDescriptor d(factory->value_string(), JSIteratorResult::kValueIndex,
@@ skipping 589 matching lines @@
         generator_function_prototype, factory->constructor_string(),
         generator_function_function,
         static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY));
 
     native_context->sloppy_generator_function_map()->SetConstructor(
         *generator_function_function);
     native_context->strict_generator_function_map()->SetConstructor(
         *generator_function_function);
   }
 
+  {  // -- F i x e d A r r a y I t e r a t o r
+    Handle<Map> map = factory->NewMap(JS_FIXED_ARRAY_ITERATOR_TYPE,
+                                      JSFixedArrayIterator::kSize);
+    Map::SetPrototype(map, iterator_prototype);
+    Map::EnsureDescriptorSlack(map, 1);
+    map->SetInObjectProperties(3);
+    map->SetConstructor(native_context->object_function());

[neis, 2016/10/11 18:36:17]

I don't know if I need this line.

+    native_context->set_fixed_array_iterator_map(*map);
+
+    {  // next
+      DataDescriptor d(factory->next_string(), JSFixedArrayIterator::kNextIndex,
+                       DONT_ENUM, Representation::Tagged());
+      map->AppendDescriptor(&d);
+    }
+  }
+
   {  // -- S e t I t e r a t o r
     Handle<JSObject> set_iterator_prototype =
         isolate->factory()->NewJSObject(isolate->object_function(), TENURED);
     JSObject::ForceSetPrototype(set_iterator_prototype, iterator_prototype);
     Handle<JSFunction> set_iterator_function = InstallFunction(
         container, "SetIterator", JS_SET_ITERATOR_TYPE, JSSetIterator::kSize,
         set_iterator_prototype, Builtins::kIllegal);
     native_context->set_set_iterator_map(set_iterator_function->initial_map());
   }
 
@@ skipping 1612 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8