Modify Enchantment and Fabric Component Map Builder Extensions

fabric-item-api-v1/build.gradle

@@ -1,6 +1,6 @@
 version = getSubprojectVersion(project)
 
-moduleDependencies(project, ['fabric-api-base'])
+moduleDependencies(project, ['fabric-api-base', 'fabric-resource-loader-v0'])
 
 testDependencies(project, [
 	':fabric-content-registries-v0',

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/EnchantmentEvents.java

@@ -18,6 +18,7 @@
 
 import net.minecraft.enchantment.Enchantment;
 import net.minecraft.item.ItemStack;
+import net.minecraft.registry.RegistryKey;
 import net.minecraft.registry.entry.RegistryEntry;
 
 import net.fabricmc.fabric.api.event.Event;
@@ -64,6 +65,27 @@ private EnchantmentEvents() { }
 			}
 	);
 
+	/**
+	 * An event that allows an {@link Enchantment} to be modified without needing to fully override an enchantment.
+	 *
+	 * <p>This should only be used to modify the behavior of <em>external</em> enchantments, where 'external' means
+	 * either vanilla or from another mod. For instance, a mod might add a bleed effect to Sharpness (and only Sharpness).
+	 * For your own enchantments, you should simply define them in your mod's data pack. See the
+	 * <a href="https://minecraft.wiki/w/Enchantment_definition">Enchantment Definition page</a> on the Minecraft Wiki
+	 * for more information.
+	 *
+	 * <p>Note: If you wish to modify the exclusive set of the enchantment, consider extending the
+	 * {@linkplain net.minecraft.registry.tag.EnchantmentTags relevant tag} through your mod's data pack instead.
+	 */
+	public static final Event<Modify> MODIFY = EventFactory.createArrayBacked(
+			Modify.class,
+			callbacks -> (key, builder, source) -> {
+				for (Modify callback : callbacks) {
+					callback.modify(key, builder, source);
+				}
+			}
+	);
+
 	@FunctionalInterface
 	public interface AllowEnchanting {
 		/**
@@ -82,4 +104,20 @@ TriState allowEnchanting(
 				EnchantingContext enchantingContext
 		);
 	}
+
+	@FunctionalInterface
+	public interface Modify {
+		/**
+		 * Modifies the effects of an {@link Enchantment}.
+		 *
+		 * @param key The ID of the enchantment
+		 * @param builder The enchantment builder
+		 * @param source The source of the enchantment
+		 */
+		void modify(
+				RegistryKey<Enchantment> key,
+				Enchantment.Builder builder,
+				EnchantmentSource source
+		);
+	}
 }

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/EnchantmentSource.java

@@ -0,0 +1,55 @@
+/*
+ * 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.item.v1;
+
+/**
+ * Determines where an enchantment has been loaded from.
+ */
+public enum EnchantmentSource {
+	/**
+	 * An enchantment loaded from the vanilla data pack.
+	 */
+	VANILLA(true),
+	/**
+	 * An enchantment loaded from mods' bundled resources.
+	 *
+	 * <p>This includes the additional builtin data packs registered by mods
+	 * with Fabric Resource Loader.
+	 */
+	MOD(true),
+	/**
+	 * An enchantment loaded from an external data pack.
+	 */
+	DATA_PACK(false);
+
+	private final boolean builtin;
+
+	EnchantmentSource(boolean builtin) {
+		this.builtin = builtin;
+	}
+
+	/**
+	 * Returns whether this enchantment source is builtin and bundled in the vanilla or mod resources.
+	 *
+	 * <p>{@link #VANILLA} and {@link #MOD} are builtin.
+	 *
+	 * @return {@code true} if builtin, {@code false} otherwise
+	 */
+	public boolean isBuiltin() {
+		return builtin;
+	}
+}

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/FabricComponentMapBuilder.java

@@ -0,0 +1,74 @@
+/*
+ * 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.item.v1;
+
+import java.util.List;
+import java.util.Objects;
+import java.util.function.Supplier;
+
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+import net.minecraft.component.ComponentType;
+
+/**
+ * Fabric-provided extensions for {@link net.minecraft.component.ComponentMap.Builder}.
+ *
+ * <p>Note: This interface is automatically implemented on all component map builders via Mixin and interface injection.
+ */
+@ApiStatus.NonExtendable
+public interface FabricComponentMapBuilder {
+	/**
+	 * Gets the current value for the component type in the builder, or creates and adds a new value if it is not present.
+	 *
+	 * @param type     The component type
+	 * @param fallback The supplier for the default data value if the type is not in this map yet. The value given by this supplier
+	 *                 may not be null.
+	 * @param <T>      The type of the component data
+	 * @return Returns the current value in the map builder, or the default value provided by the fallback if not present
+	 * @see #getOrEmpty(ComponentType)
+	 */
+	default <T> T getOrCreate(ComponentType<T> type, Supplier<@NotNull T> fallback) {
+		throw new AssertionError("Implemented in Mixin");
+	}
+
+	/**
+	 * Gets the current value for the component type in the builder, or creates and adds a new value if it is not present.
+	 *
+	 * @param type         The component type
+	 * @param defaultValue The default data value if the type is not in this map yet
+	 * @param <T>          The type of the component data
+	 * @return Returns the current value in the map builder, or the default value if not present
+	 */
+	default <T> T getOrDefault(ComponentType<T> type, @NotNull T defaultValue) {
+		Objects.requireNonNull(defaultValue, "Cannot insert null values to component map builder");
+		return getOrCreate(type, () -> defaultValue);
+	}
+
+	/**
+	 * For list component types specifically, returns a mutable list of values currently held in the builder for the given
+	 * component type. If the type is not registered to this builder yet, this will create and add a new empty list to the builder
+	 * for the type, and return that.
+	 *
+	 * @param type The component type. The component must be a list-type.
+	 * @param <T>  The type of the component entry data
+	 * @return Returns a mutable list of values for the type.
+	 */
+	default <T> List<T> getOrEmpty(ComponentType<List<T>> type) {
+		throw new AssertionError("Implemented in Mixin");
+	}
+}

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/FabricItemStack.java

@@ -23,7 +23,7 @@
 
 import net.fabricmc.fabric.api.util.TriState;
 
-/*
+/**
  * Fabric-provided extensions for {@link ItemStack}.
  * This interface is automatically implemented on all item stacks via Mixin and interface injection.
  */

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/impl/item/EnchantmentUtil.java

@@ -0,0 +1,80 @@
+/*
+ * 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.impl.item;
+
+import java.util.List;
+
+import net.minecraft.component.ComponentType;
+import net.minecraft.enchantment.Enchantment;
+import net.minecraft.registry.RegistryKey;
+import net.minecraft.resource.Resource;
+import net.minecraft.resource.ResourcePackSource;
+
+import net.fabricmc.fabric.api.item.v1.EnchantmentEvents;
+import net.fabricmc.fabric.api.item.v1.EnchantmentSource;
+import net.fabricmc.fabric.impl.resource.loader.BuiltinModResourcePackSource;
+import net.fabricmc.fabric.impl.resource.loader.FabricResource;
+import net.fabricmc.fabric.impl.resource.loader.ModResourcePackCreator;
+import net.fabricmc.fabric.mixin.item.EnchantmentBuilderAccessor;
+
+public class EnchantmentUtil {
+	@SuppressWarnings("unchecked")
+	public static Enchantment modify(RegistryKey<Enchantment> key, Enchantment originalEnchantment, EnchantmentSource source) {
+		Enchantment.Builder builder = Enchantment.builder(originalEnchantment.definition());
+		EnchantmentBuilderAccessor accessor = (EnchantmentBuilderAccessor) builder;
+
+		builder.exclusiveSet(originalEnchantment.exclusiveSet());
+		accessor.getEffectMap().addAll(originalEnchantment.effects());
+
+		originalEnchantment.effects().stream()
+				.forEach(component -> {
+					if (component.value() instanceof List<?> valueList) {
+						// component type cast is checked by the value
+						accessor.invokeGetEffectsList((ComponentType<List<Object>>) component.type())
+								.addAll(valueList);
+					}
+				});
+
+		EnchantmentEvents.MODIFY.invoker().modify(key, builder, source);
+
+		return new Enchantment(
+				originalEnchantment.description(),
+				accessor.getDefinition(),
+				accessor.getExclusiveSet(),
+				accessor.getEffectMap().build()
+		);
+	}
+
+	public static EnchantmentSource determineSource(Resource resource) {
+		if (resource != null) {
+			ResourcePackSource packSource = ((FabricResource) resource).getFabricPackSource();
+
+			if (packSource == ResourcePackSource.BUILTIN) {
+				return EnchantmentSource.VANILLA;
+			} else if (packSource == ModResourcePackCreator.RESOURCE_PACK_SOURCE || packSource instanceof BuiltinModResourcePackSource) {
+				return EnchantmentSource.MOD;
+			}
+		}
+
+		// If not builtin or mod, assume external data pack.
+		// It might also be a virtual enchantment injected via mixin instead of being loaded
+		// from a resource, but we can't determine that here.
+		return EnchantmentSource.DATA_PACK;
+	}
+
+	private EnchantmentUtil() { }
+}

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/mixin/item/ComponentMapBuilderMixin.java

@@ -0,0 +1,65 @@
+/*
+ * 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.item;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.function.Supplier;
+
+import it.unimi.dsi.fastutil.objects.Reference2ObjectMap;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+import net.minecraft.component.ComponentMap;
+import net.minecraft.component.ComponentType;
+
+import net.fabricmc.fabric.api.item.v1.FabricComponentMapBuilder;
+
+@Mixin(ComponentMap.Builder.class)
+abstract class ComponentMapBuilderMixin implements FabricComponentMapBuilder {
+	@Shadow
+	@Final
+	private Reference2ObjectMap<ComponentType<?>, Object> components;
+
+	@Shadow
+	public abstract <T> ComponentMap.Builder add(ComponentType<T> type, @Nullable T value);
+
+	@Override
+	@SuppressWarnings("unchecked")
+	public <T> T getOrCreate(ComponentType<T> type, Supplier<@NotNull T> fallback) {
+		if (!this.components.containsKey(type)) {
+			T defaultValue = fallback.get();
+			Objects.requireNonNull(defaultValue, "Cannot insert null values to component map builder");
+			this.add(type, defaultValue);
+		}
+
+		return (T) this.components.get(type);
+	}
+
+	@Override
+	public <T> List<T> getOrEmpty(ComponentType<List<T>> type) {
+		// creating a new array list guarantees that the list in the map is mutable
+		List<T> existing = new ArrayList<>(this.getOrCreate(type, Collections::emptyList));
+		this.add(type, existing);
+		return existing;
+	}
+}

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/mixin/item/EnchantmentBuilderAccessor.java

@@ -0,0 +1,43 @@
+/*
+ * 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.item;
+
+import java.util.List;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Accessor;
+import org.spongepowered.asm.mixin.gen.Invoker;
+
+import net.minecraft.component.ComponentMap;
+import net.minecraft.component.ComponentType;
+import net.minecraft.enchantment.Enchantment;
+import net.minecraft.registry.entry.RegistryEntryList;
+
+@Mixin(Enchantment.Builder.class)
+public interface EnchantmentBuilderAccessor {
+	@Accessor("definition")
+	Enchantment.Definition getDefinition();
+
+	@Accessor("exclusiveSet")
+	RegistryEntryList<Enchantment> getExclusiveSet();
+
+	@Accessor("effectMap")
+	ComponentMap.Builder getEffectMap();
+
+	@Invoker("getEffectsList")
+	<E> List<E> invokeGetEffectsList(ComponentType<List<E>> type);
+}