[async-iteration] implement Async-from-Sync Iterator

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 157 matching lines @@
   void CreateRoots();
   // Creates the empty function.  Used for creating a context from scratch.
   Handle<JSFunction> CreateEmptyFunction(Isolate* isolate);
   // Creates the ThrowTypeError function. ECMA 5th Ed. 13.2.3
   Handle<JSFunction> GetRestrictedFunctionPropertiesThrower();
   Handle<JSFunction> GetStrictArgumentsPoisonFunction();
   Handle<JSFunction> GetThrowTypeErrorIntrinsic(Builtins::Name builtin_name);
 
   void CreateStrictModeFunctionMaps(Handle<JSFunction> empty);
   void CreateIteratorMaps(Handle<JSFunction> empty);
+  void CreateAsyncIteratorMaps();
   void CreateAsyncFunctionMaps(Handle<JSFunction> empty);
   void CreateJSProxyMaps();
 
   // Make the "arguments" and "caller" properties throw a TypeError on access.
   void AddRestrictedFunctionProperties(Handle<JSFunction> empty);
 
   // Creates the global objects using the global proxy and the template passed
   // in through the API.  We call this regardless of whether we are building a
   // context from scratch or using a deserialized one from the partial snapshot
   // but in the latter case we don't use the objects it produces directly, as
@@ skipping 594 matching lines @@
   Map::SetPrototype(generator_function_map, generator_function_prototype);
   native_context()->set_generator_function_map(*generator_function_map);
 
   Handle<JSFunction> object_function(native_context()->object_function());
   Handle<Map> generator_object_prototype_map = Map::Create(isolate(), 0);
   Map::SetPrototype(generator_object_prototype_map, generator_object_prototype);
   native_context()->set_generator_object_prototype_map(
       *generator_object_prototype_map);
 }
 
+void Genesis::CreateAsyncIteratorMaps() {
+  // %AsyncIteratorPrototype%
+  // proposal-async-iteration/#sec-asynciteratorprototype
+  Handle<JSObject> async_iterator_prototype =
+      factory()->NewJSObject(isolate()->object_function(), TENURED);
+
+  Handle<JSFunction> async_iterator_prototype_iterator = SimpleCreateFunction(
+      isolate(), factory()->NewStringFromAsciiChecked("[Symbol.asyncIterator]"),
+      Builtins::kReturnReceiver, 0, true);
+
+  JSObject::AddProperty(async_iterator_prototype,
+                        factory()->async_iterator_symbol(),
+                        async_iterator_prototype_iterator, DONT_ENUM);
+
+  // %AsyncFromSyncIteratorPrototype%
+  // proposal-async-iteration/#sec-%asyncfromsynciteratorprototype%-object
+  Handle<JSObject> async_from_sync_iterator_prototype =
+      factory()->NewJSObject(isolate()->object_function(), TENURED);
+  SimpleInstallFunction(async_from_sync_iterator_prototype,
+                        factory()->next_string(),
+                        Builtins::kAsyncFromSyncIteratorPrototypeNext, 1, true);
+  SimpleInstallFunction(
+      async_from_sync_iterator_prototype, factory()->return_string(),
+      Builtins::kAsyncFromSyncIteratorPrototypeReturn, 1, true);
+  SimpleInstallFunction(
+      async_from_sync_iterator_prototype, factory()->throw_string(),
+      Builtins::kAsyncFromSyncIteratorPrototypeThrow, 1, true);
+
+  JSObject::AddProperty(
+      async_from_sync_iterator_prototype, factory()->to_string_tag_symbol(),
+      factory()->NewStringFromAsciiChecked("Async-from-Sync Iterator"),
+      static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY));
+
+  JSObject::ForceSetPrototype(async_from_sync_iterator_prototype,
+                              async_iterator_prototype);
+
+  Handle<Map> async_from_sync_iterator_map = factory()->NewMap(
+      JS_ASYNC_FROM_SYNC_ITERATOR_TYPE, JSAsyncFromSyncIterator::kSize);
+  Map::SetPrototype(async_from_sync_iterator_map,
+                    async_from_sync_iterator_prototype);
+  native_context()->set_async_from_sync_iterator_map(
+      *async_from_sync_iterator_map);
+}
+
 void Genesis::CreateAsyncFunctionMaps(Handle<JSFunction> empty) {
   // %AsyncFunctionPrototype% intrinsic
   Handle<JSObject> async_function_prototype =
       factory()->NewJSObject(isolate()->object_function(), TENURED);
   JSObject::ForceSetPrototype(async_function_prototype, empty);
 
   JSObject::AddProperty(async_function_prototype,
                         factory()->to_string_tag_symbol(),
                         factory()->NewStringFromAsciiChecked("AsyncFunction"),
                         static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY));
@@ skipping 490 matching lines @@
 
     // Install the "constructor" property on the %FunctionPrototype%.
     JSObject::AddProperty(prototype, factory->constructor_string(),
                           function_fun, DONT_ENUM);
 
     sloppy_function_map_writable_prototype_->SetConstructor(*function_fun);
     strict_function_map_writable_prototype_->SetConstructor(*function_fun);
     class_function_map_->SetConstructor(*function_fun);
   }
 
+  {
+    // --- A s y n c F r o m S y n c I t e r a t o r
+    Handle<Code> code = isolate->builtins()->AsyncIteratorValueUnwrap();
+    Handle<SharedFunctionInfo> info =
+        factory->NewSharedFunctionInfo(factory->empty_string(), code, false);
+    info->set_internal_formal_parameter_count(1);
+    info->set_length(1);
+    native_context()->set_async_iterator_value_unwrap_shared_fun(*info);
+  }
+
   {  // --- A r r a y ---
     Handle<JSFunction> array_function =
         InstallFunction(global, "Array", JS_ARRAY_TYPE, JSArray::kSize,
                         isolate->initial_object_prototype(),
                         Builtins::kArrayCode);
     array_function->shared()->DontAdaptArguments();
     array_function->shared()->set_builtin_function_id(kArrayCode);
 
     // This seems a bit hackish, but we need to make sure Array.length
     // is 1.
@@ skipping 3530 matching lines @@
       HookUpGlobalProxy(global_proxy);
     }
     DCHECK(!global_proxy->IsDetachedFrom(native_context()->global_object()));
   } else {
     DCHECK_EQ(0u, context_snapshot_index);
     // We get here if there was no context snapshot.
     CreateRoots();
     Handle<JSFunction> empty_function = CreateEmptyFunction(isolate);
     CreateStrictModeFunctionMaps(empty_function);
     CreateIteratorMaps(empty_function);
+    CreateAsyncIteratorMaps();
     CreateAsyncFunctionMaps(empty_function);
     Handle<JSGlobalObject> global_object =
         CreateNewGlobals(global_proxy_template, global_proxy);
     InitializeGlobal(global_object, empty_function, context_type);
     InitializeNormalizedMapCaches();
 
     if (!InstallNatives(context_type)) return;
 
     MakeFunctionInstancePrototypeWritable();
 
@@ skipping 142 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8