WIP [esnext] implement async iteration proposal

src/factory.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/factory.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast.h"
 #include "src/base/bits.h"
@@ skipping 1497 matching lines @@
                                         int instance_size) {
   return NewFunction(name, code, the_hole_value(), type, instance_size);
 }
 
 
 Handle<JSObject> Factory::NewFunctionPrototype(Handle<JSFunction> function) {
   // Make sure to use globals from the function's context, since the function
   // can be from a different context.
   Handle<Context> native_context(function->context()->native_context());
   Handle<Map> new_map;
-  if (IsResumableFunction(function->shared()->kind())) {
+  if (IsAsyncGeneratorFunction(function->shared()->kind())) {
+    new_map = handle(native_context->async_generator_object_prototype_map());
+  } else if (IsResumableFunction(function->shared()->kind())) {
     // Generator and async function prototypes can share maps since they
     // don't have "constructor" properties.
     new_map = handle(native_context->generator_object_prototype_map());
   } else {
     // Each function prototype gets a fresh map to avoid unwanted sharing of
     // maps between prototypes of different constructors.
     Handle<JSFunction> object_function(native_context->object_function());
     DCHECK(object_function->has_initial_map());
     new_map = handle(object_function->initial_map());
   }
@@ skipping 356 matching lines @@
 Handle<JSModuleNamespace> Factory::NewJSModuleNamespace() {
   Handle<Map> map = isolate()->js_module_namespace_map();
   return Handle<JSModuleNamespace>::cast(NewJSObjectFromMap(map));
 }
 
 Handle<JSGeneratorObject> Factory::NewJSGeneratorObject(
     Handle<JSFunction> function) {
   DCHECK(IsResumableFunction(function->shared()->kind()));
   JSFunction::EnsureHasInitialMap(function);
   Handle<Map> map(function->initial_map());
-  DCHECK_EQ(JS_GENERATOR_OBJECT_TYPE, map->instance_type());
+  DCHECK(JS_GENERATOR_OBJECT_TYPE == map->instance_type() ||
+         JS_ASYNC_GENERATOR_OBJECT_TYPE == map->instance_type());
   CALL_HEAP_FUNCTION(
       isolate(),
       isolate()->heap()->AllocateJSObjectFromMap(*map),
       JSGeneratorObject);
 }
 
 Handle<Module> Factory::NewModule(Handle<SharedFunctionInfo> code) {
   Handle<ModuleInfo> module_info(code->scope_info()->ModuleDescriptorInfo(),
                                  isolate());
   Handle<ObjectHashTable> exports =
@@ skipping 44 matching lines @@
 Handle<JSIteratorResult> Factory::NewJSIteratorResult(Handle<Object> value,
                                                       bool done) {
   Handle<Map> map(isolate()->native_context()->iterator_result_map());
   Handle<JSIteratorResult> js_iter_result =
       Handle<JSIteratorResult>::cast(NewJSObjectFromMap(map));
   js_iter_result->set_value(*value);
   js_iter_result->set_done(*ToBoolean(done));
   return js_iter_result;
 }
 
+Handle<JSAsyncFromSyncIterator> Factory::NewJSAsyncFromSyncIterator(
+    Handle<HeapObject> sync_iterator) {
+  Handle<Map> map(
+      isolate()->native_context()->initial_async_from_sync_iterator_map());
+  Handle<JSAsyncFromSyncIterator> iterator =
+      Handle<JSAsyncFromSyncIterator>::cast(NewJSObjectFromMap(map));
+
+  iterator->set_sync_iterator(*sync_iterator);
+  return iterator;
+}
+
 Handle<JSMap> Factory::NewJSMap() {
   Handle<Map> map(isolate()->native_context()->js_map_map());
   Handle<JSMap> js_map = Handle<JSMap>::cast(NewJSObjectFromMap(map));
   JSMap::Initialize(js_map, isolate());
   return js_map;
 }
 
 
 Handle<JSSet> Factory::NewJSSet() {
   Handle<Map> map(isolate()->native_context()->js_set_map());
@@ skipping 862 matching lines @@
     Handle<AccessorInfo> prototype =
         Accessors::FunctionPrototypeInfo(isolate(), rw_attribs);
     Descriptor d = Descriptor::AccessorConstant(
         Handle<Name>(Name::cast(prototype->name())), prototype, rw_attribs);
     map->AppendDescriptor(&d);
   }
 }
 
 }  // namespace internal
 }  // namespace v8