Add a way to get the name of the representation an object is based on.

src/6model/repr_registry.c

@@ -36,6 +36,7 @@ static void register_repr(PARROT_INTERP, STRING *name, REPROps *repr) {
     repr_registry[ID] = repr;
     VTABLE_set_integer_keyed_str(interp, repr_name_to_id_map, name, ID);
     repr->ID = ID;
+    repr->name = name;
 }
 
 /* Dynamically registers a representation (that is, one defined outside of

src/6model/sixmodelobject.h

@@ -262,6 +262,9 @@ struct SixModel_REPROps {
 
     /* The representation's ID. */
     INTVAL ID;
+
+    /* The representation's name. */
+    STRING *name;
 };
 
 /* Hint value to indicate the absence of an attribute lookup or method

src/ops/nqp.ops

@@ -706,6 +706,28 @@ inline op repr_change_type(in PMC, in PMC) :base_core {
     }
 }
 
+
+/*
+
+=item repr_name
+
+Takes an object and returns a string containing the name of its representation.
+
+=cut
+
+*/
+inline op repr_name(out STR, in PMC) :base_core {
+    PMC *val = decontainerize(interp, $2);
+    if (val->vtable->base_type == smo_id) {
+        $1 = REPR(val)->name;
+    }
+    else {
+        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
+            "Can only use repr_name with a SixModelObject");
+    }
+}
+
+
 /*
 
 =item type_check(obj, wanted_type)