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 8286e1ba4939cdbec62f87fb63010b3a1442a4f5..c48722bffd2ed1f05fd096b0d5852fd42878c656 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -1605,6 +1605,54 @@ bool Object::SameValueZero(Object* other) {
 }
 
 
+MaybeHandle<Object> Object::ArraySpeciesConstructor(
+    Isolate* isolate, Handle<Object> originalArray) {

[adamk, 2016/01/06 00:10:12]

original_array

[Dan Ehrenberg, 2016/01/07 00:42:58]

Done

+  Context* native_context = isolate->context()->native_context();

[adamk, 2016/01/06 00:10:12]

Please stuff this in a handle immediately; raw pointers in a handlified function
are Bad News.

[Dan Ehrenberg, 2016/01/07 00:42:58]

Oops, fixed (turns out the Handle API is more ergonomic anyway. I was sort of
assuming that the native context wouldn't go away while this was executing, but
that is not a reasonable assumption.)

+  if (!FLAG_harmony_species) {
+    return Handle<Object>(native_context->array_function(), isolate);
+  }
+  Handle<Object> constructor(isolate->heap()->undefined_value(), isolate);

[adamk, 2016/01/06 00:10:12]

isolate->factory()->undefined_value() will hand you back a handle in one fewer
step.

[Dan Ehrenberg, 2016/01/07 00:42:58]

Done

+  Maybe<bool> is_array = Object::IsArray(originalArray);
+  MAYBE_RETURN_NULL(is_array);
+  if (is_array.FromJust()) {
+    ASSIGN_RETURN_ON_EXCEPTION(
+        isolate, constructor,
+        Object::GetProperty(isolate, originalArray, "constructor", STRICT),

[adamk, 2016/01/06 00:10:12]

You can make this slightly faster by using a different GetProperty overload:

Object::GetProperty(original_array, isolate->factory()->constructor_string())

[Dan Ehrenberg, 2016/01/07 00:42:58]

Done

+        Object);
+    if (constructor->IsConstructor()) {
+      Context* constructor_context =

[adamk, 2016/01/06 00:10:12]

Again, please store in a handle.

[Dan Ehrenberg, 2016/01/07 00:42:58]

Done

+          JSFunction::cast(*constructor)->context()->native_context();
+      if (constructor_context != native_context &&
+          *constructor == constructor_context->array_function()) {
+        constructor =
+            Handle<Object>(isolate->heap()->undefined_value(), isolate);

[adamk, 2016/01/06 00:10:12]

isolate->factory()->undefined_value()

[Dan Ehrenberg, 2016/01/07 00:42:58]

Done

+      }
+    }
+    if (constructor->IsJSReceiver()) {
+      ASSIGN_RETURN_ON_EXCEPTION(
+          isolate, constructor,
+          Object::GetProperty(constructor,
+                              Handle<Name>(isolate->heap()->species_symbol())),

[adamk, 2016/01/06 00:10:12]

isolate->factory()->species_symbol()

[Dan Ehrenberg, 2016/01/07 00:42:58]

Done

+          Object);
+      if (constructor->IsNull()) {
+        constructor =
+            Handle<Object>(isolate->heap()->undefined_value(), isolate);

[adamk, 2016/01/06 00:10:12]

factory version

[Dan Ehrenberg, 2016/01/07 00:42:58]

Done

+      }
+    }
+  }
+  if (constructor->IsUndefined()) {
+    return Handle<Object>(native_context->array_function(), isolate);
+  } else {
+    if (!constructor->IsConstructor()) {
+      isolate->Throw(*isolate->factory()->NewTypeError(

[adamk, 2016/01/06 00:10:12]

I think you want to return what Throw() returns. Also you should be calling the
version that takes a Handle.

[Dan Ehrenberg, 2016/01/07 00:42:57]

Fixed

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