Add op for checking if an attr has been initialized, thus exposing on…

…e of the recent REPR additions.

src/ops/nqp.ops

@@ -353,6 +353,26 @@ inline op repr_bind_attr_str(in PMC, in PMC, in STR, in STR) :base_core {
             "Can only use repr_bind_attr_str on a SixModelObject");
 }
 
+/*
+
+=item repr_is_attr_initialized()
+
+Checks if an attribute has been initialized. Puts a non-zero value
+in $1 if so.
+
+=cut
+
+*/
+inline op repr_is_attr_initialized(out INT, in PMC, in PMC, in STR) :base_core {
+    PMC *ch = decontainerize(interp, $3);
+    if ($2->vtable->base_type == smo_id)
+        $1 = REPR($2)->is_attribute_initialized(interp, $2, ch, $4, NO_HINT);
+    else
+        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
+            "Can only use repr_is_attr_initialized on a SixModelObject");
+}
+
+
 /*
 
 =item type_check(obj, wanted_type)