Invercargill/src/lib/Promotion.vala

using Invercargill.DataStructures;
namespace Invercargill {

    private static Dictionary<Type, Type> promotion_registry = null;

    public static void register_promotion(Type generic, Type promotion) {
        if(promotion_registry == null) {
            promotion_registry = new Dictionary<Type, Type>();
        }   
        promotion_registry[generic] = promotion;
    }

    public static void resolve_promotion<T>(ref Type type) {
        if(promotion_registry == null) {
            return;
        }
        Type promotion;
        if(promotion_registry.try_get(typeof(T), out promotion)) {
            type = promotion;
        }
    }

    public interface Promotion<T> {

        public abstract Enumerable<T> wrap(Enumerable<T> enumerable) throws PromotionError;

        public abstract bool can_wrap(Type element_type);
    }

}