Add a loot table loading event

src/main/java/net/fabricmc/fabric/api/events/LootTableLoadingCallback.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2016, 2017, 2018 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.events;
+
+import net.fabricmc.fabric.api.loot.FabricLootSupplier;
+import net.fabricmc.fabric.util.HandlerArray;
+import net.fabricmc.fabric.util.HandlerRegistry;
+import net.minecraft.util.Identifier;
+
+import java.util.function.BiConsumer;
+
+/**
+ * An event handler that is called when loot tables are loaded.
+ * Use {@link #REGISTRY} to register instances.
+ */
+@FunctionalInterface
+public interface LootTableLoadingCallback extends BiConsumer<Identifier, FabricLootSupplier> {
+	final HandlerRegistry<LootTableLoadingCallback> REGISTRY = new HandlerArray<>(LootTableLoadingCallback.class);
+}

src/main/java/net/fabricmc/fabric/api/loot/FabricLootPool.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2016, 2017, 2018 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.loot;
+
+import net.minecraft.world.loot.LootPool;
+import net.minecraft.world.loot.LootTableRange;
+import net.minecraft.world.loot.UniformLootTableRange;
+import net.minecraft.world.loot.condition.LootCondition;
+import net.minecraft.world.loot.entry.LootEntry;
+import net.minecraft.world.loot.function.LootFunction;
+
+/**
+ * An interface implemented by all {@code net.minecraft.world.loot.LootPool} instances when
+ * Fabric API is present. Contains accessors for various fields.
+ */
+public interface FabricLootPool {
+	default LootPool toVanilla() {
+		return (LootPool) this;
+	}
+	LootEntry[] getEntries();
+	void setEntries(LootEntry[] entries);
+	LootCondition[] getConditions();
+	void setConditions(LootCondition[] conditions);
+	LootFunction[] getFunctions();
+	void setFunctions(LootFunction[] entries);
+	LootTableRange getRolls();
+	void setRolls(LootTableRange rolls);
+	UniformLootTableRange getBonusRolls();
+	void setBonusRolls(UniformLootTableRange bonusRolls);
+}

src/main/java/net/fabricmc/fabric/impl/loot/LootPoolAdder.java → src/main/java/net/fabricmc/fabric/api/loot/FabricLootSupplier.java

@@ -14,13 +14,22 @@
  * limitations under the License.
  */
 
-package net.fabricmc.fabric.impl.loot;
+package net.fabricmc.fabric.api.loot;
 
 import net.minecraft.world.loot.LootPool;
+import net.minecraft.world.loot.LootSupplier;
+import net.minecraft.world.loot.function.LootFunction;
 
-import java.util.List;
-
-public class LootPoolAdder {
-	public List<String> targets;
-	public List<LootPool> pools;
+/**
+ * An interface implemented by all {@code net.minecraft.world.loot.LootSupplier} instances when
+ * Fabric API is present. Contains accessors for various fields.
+ */
+public interface FabricLootSupplier {
+	default LootSupplier toVanilla() {
+		return (LootSupplier) this;
+	}
+	LootPool[] getPools();
+	void setPools(LootPool[] pools);
+	LootFunction[] getFunctions();
+	void setFunctions(LootFunction[] functions);
 }

src/main/java/net/fabricmc/fabric/mixin/loot/MixinLootManager.java

@@ -16,78 +16,35 @@
 
 package net.fabricmc.fabric.mixin.loot;
 
-import com.google.common.collect.Multimap;
-import com.google.common.collect.MultimapBuilder;
-import com.google.gson.Gson;
-import net.fabricmc.fabric.impl.loot.LootPoolAdder;
-import net.fabricmc.fabric.impl.loot.LootSupplierHooks;
-import net.minecraft.resource.Resource;
+import net.fabricmc.fabric.api.events.LootTableLoadingCallback;
+import net.fabricmc.fabric.api.loot.FabricLootSupplier;
+import net.fabricmc.fabric.util.HandlerArray;
 import net.minecraft.resource.ResourceManager;
 import net.minecraft.util.Identifier;
-import net.minecraft.util.JsonHelper;
 import net.minecraft.world.loot.LootManager;
-import net.minecraft.world.loot.LootPool;
 import net.minecraft.world.loot.LootSupplier;
-import org.apache.commons.io.IOUtils;
-import org.apache.logging.log4j.Logger;
 import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
 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 java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
 import java.util.Map;
 
 @Mixin(LootManager.class)
 public class MixinLootManager {
-	@Shadow @Final public static int jsonLength;
-	@Shadow @Final private static Logger LOGGER;
-	@Shadow @Final private static Gson gson;
 	@Shadow @Final private Map<Identifier, LootSupplier> suppliers;
-	private static final String PATH = "loot_pools";
-	private static final int PATH_LENGTH = PATH.length() + 1; // Includes the slash as well
-
-	/**
-	 * A map of loot pools adders with the keys being the targets.
-	 */
-	private final Multimap<Identifier, LootPoolAdder> lootPoolAdders = MultimapBuilder.hashKeys().hashSetValues().build();
-
-	@Inject(method = "onResourceReload", at = @At("HEAD"))
-	private void loadAdders(ResourceManager manager, CallbackInfo info) {
-		manager.findResources(PATH, (name) -> name.endsWith(".json")).forEach(fullId -> {
-			String originalPath = fullId.getPath();
-			Identifier id = new Identifier(fullId.getNamespace(), originalPath.substring(PATH_LENGTH, originalPath.length() - jsonLength));
-			try {
-				try (Resource resource = manager.getResource(fullId)) {
-					LootPoolAdder adder = JsonHelper.deserialize(gson, IOUtils.toString(resource.getInputStream(), StandardCharsets.UTF_8), LootPoolAdder.class);
-					if (adder != null) {
-						if (adder.targets.size() == 0) {
-							LOGGER.warn("[Fabric] Loot pool adder {} has no targets", id);
-						}
-
-						for (String target : adder.targets) {
-							lootPoolAdders.put(new Identifier(target), adder);
-						}
-					}
-				}
-			} catch (Throwable t) {
-				LOGGER.error("[Fabric] Couldn't read loot pool adder {} from {}", id, fullId, t);
-			}
-		});
-	}
 
 	@Inject(method = "onResourceReload", at = @At("RETURN"))
-	private void injectAdders(ResourceManager manager, CallbackInfo info) {
+	private void onResourceReload(ResourceManager manager, CallbackInfo info) {
 		suppliers.forEach((id, supplier) -> {
-			ArrayList<LootPool> pools = new ArrayList<>();
-			for (LootPoolAdder adder : lootPoolAdders.get(id)) {
-				pools.addAll(adder.pools);
-			}
+			LootTableLoadingCallback[] handlers = ((HandlerArray<LootTableLoadingCallback>) LootTableLoadingCallback.REGISTRY)
+					.getBackingArray();
 
-			((LootSupplierHooks) supplier).fabric_addPools(pools.toArray(new LootPool[0]));
+			for (LootTableLoadingCallback handler : handlers) {
+				handler.accept(id, (FabricLootSupplier) supplier);
+			}
 		});
 	}
 }

src/main/java/net/fabricmc/fabric/mixin/loot/MixinLootPool.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2016, 2017, 2018 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.loot;
+
+import net.fabricmc.fabric.api.loot.FabricLootPool;
+import net.minecraft.world.loot.LootPool;
+import net.minecraft.world.loot.LootTableRange;
+import net.minecraft.world.loot.UniformLootTableRange;
+import net.minecraft.world.loot.condition.LootCondition;
+import net.minecraft.world.loot.entry.LootEntry;
+import net.minecraft.world.loot.function.LootFunction;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Accessor;
+
+@Mixin(LootPool.class)
+public interface MixinLootPool extends FabricLootPool {
+	@Accessor
+	@Override
+	LootEntry[] getEntries();
+
+	@Accessor
+	@Override
+	LootCondition[] getConditions();
+
+	@Accessor
+	@Override
+	LootFunction[] getFunctions();
+
+	@Accessor
+	@Override
+	LootTableRange getRolls();
+
+	@Accessor
+	@Override
+	UniformLootTableRange getBonusRolls();
+
+	@Accessor
+	@Override
+	void setEntries(LootEntry[] entries);
+
+	@Accessor
+	@Override
+	void setConditions(LootCondition[] conditions);
+
+	@Accessor
+	@Override
+	void setFunctions(LootFunction[] entries);
+
+	@Accessor
+	@Override
+	void setRolls(LootTableRange rolls);
+
+	@Accessor
+	@Override
+	void setBonusRolls(UniformLootTableRange bonusRolls);
+}

src/main/java/net/fabricmc/fabric/mixin/loot/MixinLootSupplier.java

@@ -16,23 +16,28 @@
 
 package net.fabricmc.fabric.mixin.loot;
 
-import net.fabricmc.fabric.impl.loot.LootSupplierHooks;
+import net.fabricmc.fabric.api.loot.FabricLootSupplier;
 import net.minecraft.world.loot.LootPool;
 import net.minecraft.world.loot.LootSupplier;
-import org.spongepowered.asm.mixin.Final;
+import net.minecraft.world.loot.function.LootFunction;
 import org.spongepowered.asm.mixin.Mixin;
-import org.spongepowered.asm.mixin.Mutable;
-import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.gen.Accessor;
 
 @Mixin(LootSupplier.class)
-public class MixinLootSupplier implements LootSupplierHooks {
-	@Shadow @Final @Mutable private LootPool[] pools;
+public interface MixinLootSupplier extends FabricLootSupplier {
+	@Accessor
+	@Override
+	LootPool[] getPools();
+
+	@Accessor
+	@Override
+	void setPools(LootPool[] pools);
+
+	@Accessor
+	@Override
+	LootFunction[] getFunctions();
 
+	@Accessor
 	@Override
-	public void fabric_addPools(LootPool[] pools) {
-		LootPool[] oldPools = this.pools;
-		this.pools = new LootPool[oldPools.length + pools.length];
-		System.arraycopy(oldPools, 0, this.pools, 0, oldPools.length);
-		System.arraycopy(pools, 0, this.pools, oldPools.length, pools.length);
-	}
+	void setFunctions(LootFunction[] functions);
 }

src/main/resources/net.fabricmc.fabric.mixins.common.json

@@ -20,6 +20,7 @@
     "item.MixinAbstractFurnaceBlockEntity",
     "itemgroup.MixinItemGroup",
     "loot.MixinLootManager",
+    "loot.MixinLootPool",
     "loot.MixinLootSupplier",
     "misc.MixinCrashReport",
     "networking.MixinServerPlayNetworkHandler",

src/test/java/net/fabricmc/fabric/loot/LootTableMod.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2016, 2017, 2018 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.loot;
+
+import net.fabricmc.api.ModInitializer;
+import net.fabricmc.fabric.api.events.LootTableLoadingCallback;
+import net.minecraft.item.Items;
+import net.minecraft.world.loot.ConstantLootTableRange;
+import net.minecraft.world.loot.LootPool;
+import net.minecraft.world.loot.condition.SurvivesExplosionLootCondition;
+import net.minecraft.world.loot.entry.ItemEntry;
+
+import java.util.Arrays;
+
+public class LootTableMod implements ModInitializer {
+	@Override
+	public void onInitialize() {
+		LootTableLoadingCallback.REGISTRY.register((id, supplier) -> {
+			if ("minecraft:blocks/dirt".equals(id.toString())) {
+				LootPool[] pools = Arrays.copyOf(supplier.getPools(), supplier.getPools().length + 1);
+				pools[pools.length - 1] = LootPool.create()
+						.withEntry(ItemEntry.builder(Items.FEATHER))
+						.withRolls(ConstantLootTableRange.create(1))
+						.withCondition(SurvivesExplosionLootCondition.method_871())
+						.build();
+
+				supplier.setPools(pools);
+			}
+		});
+	}
+}