[runtime] [proxy] implement [[Construct]]

src/runtime/runtime-proxy.cc

Index: src/runtime/runtime-proxy.cc
diff --git a/src/runtime/runtime-proxy.cc b/src/runtime/runtime-proxy.cc
index c501893db32ec038a4405160c97c225cebed8f33..67b81f8668aac3f7adbbf579a198002946ffc2a0 100644
--- a/src/runtime/runtime-proxy.cc
+++ b/src/runtime/runtime-proxy.cc
@@ -73,6 +73,75 @@ RUNTIME_FUNCTION(Runtime_JSProxyCall) {
 }
 
 
+// 9.5.14 [[Construct]] (argumentsList, newTarget)
+RUNTIME_FUNCTION(Runtime_JSProxyConstruct) {
+  HandleScope scope(isolate);
+  DCHECK_LE(2, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(JSProxy, proxy, args.length() - 2);
+  CONVERT_ARG_HANDLE_CHECKED(Object, new_target, args.length() - 1);
+  Handle<String> trap_name = isolate->factory()->construct_string();
+
+  // 1. Let handler be the value of the [[ProxyHandler]] internal slot of O.
+  Handle<Object> handler(proxy->handler(), isolate);
+  // 2. If handler is null, throw a TypeError exception.
+  if (proxy->IsRevoked()) {
+    THROW_NEW_ERROR_RETURN_FAILURE(
+        isolate, NewTypeError(MessageTemplate::kProxyRevoked, trap_name));
+  }
+  // 3. Assert: Type(handler) is Object.
+  DCHECK(handler->IsJSReceiver());
+  // 4. Let target be the value of the [[ProxyTarget]] internal slot of O.
+  Handle<JSReceiver> target(JSReceiver::cast(proxy->target()), isolate);
+  // 5. Let trap be ? GetMethod(handler, "construct").
+  Handle<Object> trap;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, trap,
+      Object::GetMethod(Handle<JSReceiver>::cast(handler), trap_name));
+  // 6. If trap is undefined, then
+  int const arguments_length = args.length() - 3;
+  if (trap->IsUndefined()) {
+    // 6.a. Assert: target has a [[Construct]] internal method.
+    DCHECK(target->IsConstructor());
+    // 6.b. Return Construct(target, argumentsList, newTarget).
+    ScopedVector<Handle<Object>> argv(arguments_length);
+    for (int i = 0; i < arguments_length; ++i) {
+      argv[i] = args.at<Object>(i + 1);
+    }
+    Handle<Object> result;
+    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+        isolate, result, Execution::New(isolate, target, new_target,
+                                        arguments_length, argv.start()));
+    return *result;
+  }
+  // 7. Let argArray be CreateArrayFromList(argumentsList).
+  Handle<JSArray> arg_array = isolate->factory()->NewJSArray(

[Toon Verwaest, 2015/12/08 20:27:22]

Could you add a test that this array is created in the right realm for 2 cases:

(new proxy) should get an array from the outer realm. (Add a test that
constructs a proxy from a second realm from the first realm.)

Reflect.construct(proxy) should get an array from the realm of the construct
method on Reflect. (So create 3 realms and all from the first to
Reflect.construct from the second with a proxy target from the third. The array
has to be from the second.)

Callable proxies inherit the realm from their target.

+      FAST_ELEMENTS, arguments_length, arguments_length);
+  ElementsAccessor* accessor = arg_array->GetElementsAccessor();
+  {
+    DisallowHeapAllocation no_gc;
+    FixedArrayBase* elements = arg_array->elements();
+    for (int i = 0; i < arguments_length; i++) {
+      accessor->Set(elements, i, args[i + 1]);
+    }
+  }
+  // 8. Let newObj be ? Call(trap, handler, «target, argArray, newTarget »).
+  Handle<Object> new_object;
+  Handle<Object> trap_args[] = {target, arg_array, new_target};
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, new_object,
+      Execution::Call(isolate, trap, handler, arraysize(trap_args), trap_args));
+  // 9. If Type(newObj) is not Object, throw a TypeError exception.
+  if (!new_object->IsJSReceiver()) {
+    THROW_NEW_ERROR_RETURN_FAILURE(
+        isolate,
+        NewTypeError(MessageTemplate::kProxyTrapConstructMustReturnObject,
+                     new_object));
+  }
+  // 10. Return newObj.
+  return *new_object;
+}
+
+
 RUNTIME_FUNCTION(Runtime_IsJSProxy) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);