Provide a way for libs to register containers.

This means that Rakudo will be able to set up its scalar handling.

Author: jnthn

src/6model/containers.c

@@ -130,6 +130,12 @@ ContainerConfigurer * SixModelObject_get_container_config(PARROT_INTERP, STRING
 /* Does initial setup work of the container registry, including registering
  * the various built-in container types. */
 void SixModelObject_containers_setup(PARROT_INTERP) {
+    /* Set up object for dynamically registering extra configurers. */
+    PMC *dyn_reg_func = Parrot_pmc_new(interp, enum_class_Pointer);
+    VTABLE_set_pointer(interp, dyn_reg_func, SixModelObject_add_container_config);
+    VTABLE_set_pmc_keyed_str(interp, interp->root_namespace,
+        Parrot_str_new_constant(interp, "_REGISTER_CONTCONF"), dyn_reg_func);
+    
     /* Initialize registry. */
     container_registry = Parrot_pmc_new(interp, enum_class_Hash);
     Parrot_pmc_gc_register(interp, container_registry);

src/6model/sixmodelobject.h

@@ -476,4 +476,12 @@ typedef INTVAL (* rf) (PARROT_INTERP, STRING *name, REPROps * (*reg) (PARROT_INT
             VTABLE_get_pmc_keyed_str(interp, interp->root_namespace, \
                 Parrot_str_new_constant(interp, "_REGISTER_REPR"))))(interp, name, reg_func)
 
+/* Dynamic container configuration registration. */
+typedef void (*cspec_conf) (PARROT_INTERP, STRING *name, ContainerConfigurer *configurer);
+#define REGISTER_DYNAMIC_CONTAINER_CONFIG(interp, name, configurer) \
+    ((cspec_conf) \
+        VTABLE_get_pointer(interp, \
+            VTABLE_get_pmc_keyed_str(interp, interp->root_namespace, \
+                Parrot_str_new_constant(interp, "_REGISTER_CONTCONF"))))(interp, name, configurer)
+
 #endif