Class RegistryObject

src/main/java/net/minecraftforge/fml/RegistryObject.java:39–313

import java.util.stream.Stream;

public final class RegistryObject<T extends IForgeRegistryEntry<? super T>> implements Supplier<T>
{
    private final ResourceLocation name;
    @Nullable
    private T value;

    public static <T extends IForgeRegistryEntry<T>, U extends T> RegistryObject<U> of(final ResourceLocation name, Supplier<Class<? super T>> registryType) {
        return new RegistryObject<>(name, registryType);
    }

    public static <T extends IForgeRegistryEntry<T>, U extends T> RegistryObject<U> of(final ResourceLocation name, IForgeRegistry<T> registry) {
        return new RegistryObject<>(name, registry);
    }

    public static <T extends IForgeRegistryEntry<T>, U extends T> RegistryObject<U> of(final ResourceLocation name, final Class<T> baseType, String modid) {
        return new RegistryObject<>(name, baseType, modid);
    }

    private static RegistryObject<?> EMPTY = new RegistryObject<>();

    private static <T extends IForgeRegistryEntry<? super T>> RegistryObject<T> empty() {
        @SuppressWarnings("unchecked")
        RegistryObject<T> t = (RegistryObject<T>) EMPTY;
        return t;
    }

    private RegistryObject() {
        this.name = null;
    }

    private <V extends IForgeRegistryEntry<V>> RegistryObject(ResourceLocation name, Supplier<Class<? super V>> registryType)
    {
        this(name, RegistryManager.ACTIVE.<V>getRegistry(registryType.get()));
    }

    @SuppressWarnings("unchecked")
    private <V extends IForgeRegistryEntry<V>> RegistryObject(ResourceLocation name, IForgeRegistry<V> registry)
    {
        if (registry == null)
            throw new IllegalArgumentException("Invalid registry argument, must not be null");
        this.name = name;
        ObjectHolderRegistry.addHandler(pred ->
        {
            if (pred.test(registry.getRegistryName()))
                this.value = registry.containsKey(this.name) ? (T)registry.getValue(this.name) : null;
        });
    }

    @SuppressWarnings("unchecked")
    private <V extends IForgeRegistryEntry<V>> RegistryObject(final ResourceLocation name, final Class<V> baseType, final String modid)
    {
        this.name = name;
        final Throwable callerStack = new Throwable("Calling Site from mod: " + modid);
        ObjectHolderRegistry.addHandler(new Consumer<Predicate<ResourceLocation>>()
        {
            private IForgeRegistry<V> registry;

            @Override