chore: fix registrar type safety

specter-core/src/main/java/dev/spiritstudios/specter/api/core/util/ReflectionHelper.java

@@ -2,9 +2,11 @@
 
 import org.objectweb.asm.tree.AnnotationNode;
 
+import java.lang.annotation.Annotation;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Modifier;
+import java.util.Optional;
 
 /**
  * A bunch of utilities to reduce boilerplate reflection code.
@@ -125,6 +127,10 @@ public static void setFieldValue(Object instance, Field field, Object value) {
 		}
 	}
 
+	public static <T extends Annotation> Optional<T> getAnnotation(Field field, Class<T> annotationClass) {
+		return Optional.ofNullable(field.getAnnotation(annotationClass));
+	}
+
 	@SuppressWarnings("unchecked")
 	public static <T> T getAnnotationValue(AnnotationNode annotation, String key, T defaultValue) {
 		if (annotation == null || annotation.values == null) return defaultValue;

specter-registry/src/main/java/dev/spiritstudios/specter/api/registry/registration/BlockEntityTypeRegistrar.java

@@ -9,4 +9,9 @@ public interface BlockEntityTypeRegistrar extends MinecraftRegistrar<BlockEntity
 	default Registry<BlockEntityType<?>> getRegistry() {
 		return Registries.BLOCK_ENTITY_TYPE;
 	}
+
+	@Override
+	default Class<BlockEntityType<?>> getObjectType() {
+		return Registrar.fixGenerics(BlockEntityType.class);
+	}
 }

specter-registry/src/main/java/dev/spiritstudios/specter/api/registry/registration/BlockRegistrar.java

@@ -19,6 +19,11 @@ default Registry<Block> getRegistry() {
 		return Registries.BLOCK;
 	}
 
+	@Override
+	default Class<Block> getObjectType() {
+		return Block.class;
+	}
+
 	@Override
 	default void register(String name, String namespace, Block object, Field field) {
 		Registry.register(getRegistry(), Identifier.of(namespace, name), object);

specter-registry/src/main/java/dev/spiritstudios/specter/api/registry/registration/EntityTypeRegistrar.java

@@ -9,4 +9,9 @@ public interface EntityTypeRegistrar extends MinecraftRegistrar<EntityType<?>> {
 	default Registry<EntityType<?>> getRegistry() {
 		return Registries.ENTITY_TYPE;
 	}
+
+	@Override
+	default Class<EntityType<?>> getObjectType() {
+		return Registrar.fixGenerics(EntityType.class);
+	}
 }

specter-registry/src/main/java/dev/spiritstudios/specter/api/registry/registration/ItemRegistrar.java

@@ -9,4 +9,9 @@ public interface ItemRegistrar extends MinecraftRegistrar<Item> {
 	default Registry<Item> getRegistry() {
 		return Registries.ITEM;
 	}
+
+	@Override
+	default Class<Item> getObjectType() {
+		return Item.class;
+	}
 }

specter-registry/src/main/java/dev/spiritstudios/specter/api/registry/registration/Registrar.java

@@ -8,7 +8,6 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 import java.lang.reflect.Field;
-import java.lang.reflect.Modifier;
 
 /**
  * Automatically run a function on each object using reflection.
@@ -32,6 +31,15 @@ static <T> void process(Class<? extends Registrar<T>> clazz, String namespace) {
 		registrar.init(namespace);
 	}
 
+	/**
+	 * Workaround for Java's type erasure.
+	 * Use this if {@link T} has a generic type of ?.
+	 */
+	@SuppressWarnings("unchecked")
+	static <T> Class<T> fixGenerics(Class<?> clazz) {
+		return (Class<T>) clazz;
+	}
+
 	/**
 	 * Register an object to the registry.
 	 *
@@ -42,6 +50,14 @@ static <T> void process(Class<? extends Registrar<T>> clazz, String namespace) {
 	 */
 	void register(String name, String namespace, T object, Field field);
 
+	/**
+	 * Get the type of object to register.
+	 * If {@link T} has a generic type of ?, use {@link Registrar#fixGenerics(Class)} to force the correct type.
+	 *
+	 * @return The type of object to register
+	 */
+	Class<T> getObjectType();
+
 	/**
 	 * Initialize the registrar and register all objects.
 	 * Do not call this method directly, use {@link Registrar#process(Class, String)} instead.
@@ -50,20 +66,15 @@ static <T> void process(Class<? extends Registrar<T>> clazz, String namespace) {
 	 */
 	@ApiStatus.Internal
 	default void init(String namespace) {
-		for (Field field : this.getClass().getDeclaredFields()) {
-			if (!Modifier.isStatic(field.getModifiers()) || field.isAnnotationPresent(Ignore.class)) continue;
+		ReflectionHelper.forEachStaticField(this.getClass(), getObjectType(), (value, name, field) -> {
+			if (field.isAnnotationPresent(Ignore.class)) return;
 
-			T value = ReflectionHelper.getFieldValue(field);
-			if (value == null || !field.getType().isAssignableFrom(value.getClass())) continue;
-
-			String name = field.getName().toLowerCase();
-			if (field.isAnnotationPresent(Name.class)) {
-				Name nameAnnotation = field.getAnnotation(Name.class);
-				name = nameAnnotation.value();
-			}
+			String objectName = ReflectionHelper.getAnnotation(field, Name.class)
+				.map(Name::value)
+				.orElseGet(name::toLowerCase);
 
-			register(name, namespace, value, field);
-		}
+			register(objectName, namespace, value, field);
+		});
 	}
 
 	/**

specter-registry/src/main/java/dev/spiritstudios/specter/api/registry/registration/SoundEventRegistrar.java

@@ -1,5 +1,6 @@
 package dev.spiritstudios.specter.api.registry.registration;
 
+import net.minecraft.registry.Registries;
 import net.minecraft.registry.Registry;
 import net.minecraft.sound.SoundEvent;
 import net.minecraft.util.Identifier;
@@ -15,4 +16,14 @@ public interface SoundEventRegistrar extends MinecraftRegistrar<SoundEvent> {
 	default void register(String name, String namespace, SoundEvent object, Field field) {
 		Registry.register(getRegistry(), Identifier.of(namespace, name.replace('-', '.')), object);
 	}
+
+	@Override
+	default Registry<SoundEvent> getRegistry() {
+		return Registries.SOUND_EVENT;
+	}
+
+	@Override
+	default Class<SoundEvent> getObjectType() {
+		return SoundEvent.class;
+	}
 }