Entity attribute registry (#568)

fabric-object-builders-v0/src/main/java/net/fabricmc/fabric/api/entity/FabricDefaultAttributeRegistry.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.api.entity;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import net.minecraft.entity.EntityType;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.attribute.DefaultAttributeContainer;
+import net.minecraft.util.registry.Registry;
+
+import net.fabricmc.fabric.mixin.object.builder.DefaultAttributeRegistryAccessor;
+
+/**
+ * Allows registering custom default attributes for living entities.
+ *
+ * <p>All living entity types must have default attributes registered. See {@link
+ * FabricEntityTypeBuilder} for utility on entity type registration in general.</p>
+ *
+ * <p>A registered default attribute for an entity type can be retrieved through
+ * {@link net.minecraft.entity.attribute.DefaultAttributeRegistry#get(EntityType)}.</p>
+ *
+ * @see net.minecraft.entity.attribute.DefaultAttributeRegistry
+ * @deprecated Experimental feature, may be removed or changed without further notice.
+ * Vanilla snapshot feature, subject to vanilla change.
+ */
+@Deprecated
+public final class FabricDefaultAttributeRegistry {
+	/**
+	 * Private logger, not exposed.
+	 */
+	private static final Logger LOGGER = LogManager.getLogger();
+
+	/**
+	 * Registers a default attribute for a type of living entity.
+	 *
+	 * <p>It can be used in a fashion similar to this:
+	 * <blockquote><pre>
+	 * EntityAttributeRegistry.INSTANCE.register(type, LivingEntity.createLivingAttributes());
+	 * </pre></blockquote>
+	 * </p>
+	 *
+	 * <p>If a registration overrides another, a debug log message will be emitted. Existing registrations
+	 * can be checked at {@link net.minecraft.entity.attribute.DefaultAttributeRegistry#hasDefinitionFor(EntityType)}.</p>
+	 *
+	 * @param type    the entity type
+	 * @param builder the builder that creates the default attribute
+	 */
+	public static void register(EntityType<? extends LivingEntity> type, DefaultAttributeContainer.Builder builder) {
+		if (DefaultAttributeRegistryAccessor.getRegistry().put(type, builder.build()) != null) {
+			LOGGER.debug("Overriding existing registration for entity type {}", Registry.ENTITY_TYPE.getId(type));
+		}
+	}
+}

fabric-object-builders-v0/src/main/java/net/fabricmc/fabric/api/entity/FabricEntityTypeBuilder.java

@@ -33,6 +33,9 @@ import net.fabricmc.fabric.impl.object.builder.FabricEntityType;
  * Extended version of {@link EntityType.Builder} with added registration for
  * server->client entity tracking values.
  *
+ * <p>For living entities, they must have {@link FabricDefaultAttributeRegistry
+ * default attributes registered} after the entity type is registered.</p>
+ *
  * @param <T> Entity class.
  */
 // TODO more javadocs

fabric-object-builders-v0/src/main/java/net/fabricmc/fabric/mixin/object/builder/DefaultAttributeRegistryAccessor.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.mixin.object.builder;
+
+import java.util.Map;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Accessor;
+
+import net.minecraft.entity.EntityType;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.attribute.DefaultAttributeContainer;
+import net.minecraft.entity.attribute.DefaultAttributeRegistry;
+
+@Mixin(DefaultAttributeRegistry.class)
+public interface DefaultAttributeRegistryAccessor {
+	@Accessor("DEFAULT_ATTRIBUTE_REGISTRY")
+	static Map<EntityType<? extends LivingEntity>, DefaultAttributeContainer> getRegistry() {
+		throw new AssertionError("mixin dummy");
+	}
+}

fabric-object-builders-v0/src/main/java/net/fabricmc/fabric/mixin/object/builder/DefaultAttributeRegistryMixin.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.mixin.object.builder;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Mutable;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import net.minecraft.entity.EntityType;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.attribute.DefaultAttributeContainer;
+import net.minecraft.entity.attribute.DefaultAttributeRegistry;
+
+@Mixin(DefaultAttributeRegistry.class)
+public abstract class DefaultAttributeRegistryMixin {
+	@Shadow
+	@Final
+	@Mutable
+	private static Map<EntityType<? extends LivingEntity>, DefaultAttributeContainer> DEFAULT_ATTRIBUTE_REGISTRY;
+
+	@Inject(method = "<clinit>*", at = @At("TAIL"))
+	private static void injectAttributes(CallbackInfo ci) {
+		DEFAULT_ATTRIBUTE_REGISTRY = new HashMap<>(DEFAULT_ATTRIBUTE_REGISTRY);
+	}
+}

fabric-object-builders-v0/src/main/resources/fabric-object-builders-v0.mixins.json

@@ -4,6 +4,8 @@
   "compatibilityLevel": "JAVA_8",
   "mixins": [
     "BlockSettingsHooks",
+    "DefaultAttributeRegistryAccessor",
+    "DefaultAttributeRegistryMixin",
     "MaterialBuilderHooks",
     "MixinBlock",
     "MixinItem"