Add Array support for @@species and subclassing

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index a69ab75ebdffaff2e3ee76339b7a4ed38fe7bdad..c2f84e8749d1f724dc394a0179160dc1b72abb4f 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -1605,6 +1605,55 @@ bool Object::SameValueZero(Object* other) {
 }
 
 
+MaybeHandle<Object> Object::ArraySpeciesConstructor(
+    Isolate* isolate, Handle<Object> original_array) {
+  Handle<Context> native_context = isolate->native_context();
+  if (!FLAG_harmony_species) {
+    return Handle<Object>(native_context->array_function(), isolate);
+  }
+  Handle<Object> constructor = isolate->factory()->undefined_value();
+  Maybe<bool> is_array = Object::IsArray(original_array);
+  MAYBE_RETURN_NULL(is_array);
+  if (is_array.FromJust()) {
+    ASSIGN_RETURN_ON_EXCEPTION(
+        isolate, constructor,
+        Object::GetProperty(original_array,
+                            isolate->factory()->constructor_string()),
+        Object);
+    if (constructor->IsConstructor()) {
+      Handle<Context> constructor_context;
+      ASSIGN_RETURN_ON_EXCEPTION(
+          isolate, constructor_context,
+          JSReceiver::GetFunctionRealm(Handle<JSReceiver>::cast(constructor)),

[adamk, 2016/01/07 01:11:04]

Did this need changing to make proxies work? Can you add a test where a Proxy is
shows up here?

[Dan Ehrenberg, 2016/01/07 01:35:17]

Yeah, you caught me. I couldn't think of a great test that really exercised
their Proxy-ness, but I added a test that makes sure that things don't crash in
this case.

[adamk, 2016/01/07 01:38:30]

Not crashing is sufficient to allay my fears.

+          Object);
+      if (*constructor_context != *native_context &&
+          *constructor == constructor_context->array_function()) {
+        constructor = isolate->factory()->undefined_value();
+      }
+    }
+    if (constructor->IsJSReceiver()) {
+      ASSIGN_RETURN_ON_EXCEPTION(
+          isolate, constructor,
+          Object::GetProperty(constructor,
+                              isolate->factory()->species_symbol()),
+          Object);
+      if (constructor->IsNull()) {
+        constructor = isolate->factory()->undefined_value();
+      }
+    }
+  }
+  if (constructor->IsUndefined()) {
+    return Handle<Object>(native_context->array_function(), isolate);
+  } else {
+    if (!constructor->IsConstructor()) {
+      return isolate->Throw<Object>(isolate->factory()->NewTypeError(

[adamk, 2016/01/07 01:11:04]

Looks like there's a macro for this:

THROW_NEW_ERROR(isolate,
                NewTypeError(MessageTemplate::kSpeciesNotConstructor),
                Object);

I'm not totally sure that's worth a macro, but it's what all the other code in
objects.cc does, so I'd prefer consistency here.

[Dan Ehrenberg, 2016/01/07 01:35:17]

OK, sure.

[adamk, 2016/01/07 01:38:30]

Sorry, it's the week of macros!

+          MessageTemplate::kSpeciesNotConstructor));
+    }
+    return constructor;
+  }
+}
+
+
 void Object::ShortPrint(FILE* out) {
   OFStream os(out);
   os << Brief(this);