Fix #2552: Add way to use resource conditions for block loot table datagen

fabric-data-generation-api-v1/src/main/java/net/fabricmc/fabric/api/datagen/v1/loot/FabricBlockLootTableGenerator.java

@@ -0,0 +1,41 @@
+/*
+ * 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.datagen.v1.loot;
+
+import com.google.common.base.Preconditions;
+
+import net.minecraft.data.server.loottable.BlockLootTableGenerator;
+
+import net.fabricmc.fabric.api.resource.conditions.v1.ConditionJsonProvider;
+import net.fabricmc.fabric.impl.datagen.loot.ConditionBlockLootTableGenerator;
+
+/**
+ * Fabric-provided extensions for {@link BlockLootTableGenerator}.
+ *
+ * <p>Note: This interface is automatically implemented via Mixin and interface injection.
+ */
+public interface FabricBlockLootTableGenerator {
+	/**
+	 * Return a new generator that applies the specified conditions to any loot table it receives,
+	 * and then forwards the loot tables to this generator.
+	 */
+	default BlockLootTableGenerator withConditions(ConditionJsonProvider... conditions) {
+		Preconditions.checkArgument(conditions.length > 0, "Must add at least one condition.");
+
+		return new ConditionBlockLootTableGenerator((BlockLootTableGenerator) this, conditions);
+	}
+}

fabric-data-generation-api-v1/src/main/java/net/fabricmc/fabric/api/datagen/v1/provider/FabricLootTableProvider.java

@@ -39,6 +39,7 @@
 import net.minecraft.util.Identifier;
 
 import net.fabricmc.fabric.api.datagen.v1.FabricDataOutput;
+import net.fabricmc.fabric.api.datagen.v1.loot.FabricBlockLootTableGenerator;
 import net.fabricmc.fabric.api.resource.conditions.v1.ConditionJsonProvider;
 import net.fabricmc.fabric.impl.datagen.FabricDataGenHelper;
 
@@ -57,6 +58,8 @@ public interface FabricLootTableProvider extends Consumer<BiConsumer<Identifier,
 
 	/**
 	 * Return a new exporter that applies the specified conditions to any loot table it receives.
+	 *
+	 * <p>For block loot tables, use {@link FabricBlockLootTableGenerator#withConditions} instead.
 	 */
 	default BiConsumer<Identifier, LootTable.Builder> withConditions(BiConsumer<Identifier, LootTable.Builder> exporter, ConditionJsonProvider... conditions) {
 		Preconditions.checkArgument(conditions.length > 0, "Must add at least one condition.");

fabric-data-generation-api-v1/src/main/java/net/fabricmc/fabric/impl/datagen/loot/ConditionBlockLootTableGenerator.java

@@ -0,0 +1,50 @@
+/*
+ * 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.datagen.loot;
+
+import java.util.Collections;
+
+import net.minecraft.block.Block;
+import net.minecraft.data.server.loottable.BlockLootTableGenerator;
+import net.minecraft.loot.LootTable;
+import net.minecraft.resource.featuretoggle.FeatureFlags;
+
+import net.fabricmc.fabric.api.resource.conditions.v1.ConditionJsonProvider;
+import net.fabricmc.fabric.impl.datagen.FabricDataGenHelper;
+
+public class ConditionBlockLootTableGenerator extends BlockLootTableGenerator {
+	private final BlockLootTableGenerator parent;
+	private final ConditionJsonProvider[] conditions;
+
+	public ConditionBlockLootTableGenerator(BlockLootTableGenerator parent, ConditionJsonProvider[] conditions) {
+		super(Collections.emptySet(), FeatureFlags.FEATURE_MANAGER.getFeatureSet());
+
+		this.parent = parent;
+		this.conditions = conditions;
+	}
+
+	@Override
+	public void generate() {
+		throw new UnsupportedOperationException("generate() should not be called.");
+	}
+
+	@Override
+	public void addDrop(Block block, LootTable.Builder lootTable) {
+		FabricDataGenHelper.addConditions(lootTable, conditions);
+		this.parent.addDrop(block, lootTable);
+	}
+}

fabric-data-generation-api-v1/src/main/java/net/fabricmc/fabric/mixin/datagen/loot/BlockLootTableGeneratorMixin.java

@@ -0,0 +1,27 @@
+/*
+ * 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.datagen.loot;
+
+import org.spongepowered.asm.mixin.Mixin;
+
+import net.minecraft.data.server.loottable.BlockLootTableGenerator;
+
+import net.fabricmc.fabric.api.datagen.v1.loot.FabricBlockLootTableGenerator;
+
+@Mixin(BlockLootTableGenerator.class)
+public class BlockLootTableGeneratorMixin implements FabricBlockLootTableGenerator {
+}

fabric-data-generation-api-v1/src/main/resources/fabric-data-generation-api-v1.mixins.json

@@ -3,6 +3,7 @@
   "package": "net.fabricmc.fabric.mixin.datagen",
   "compatibilityLevel": "JAVA_16",
   "mixins": [
+    "loot.BlockLootTableGeneratorMixin",
     "AbstractTagProviderMixin",
     "ModelProviderMixin",
     "TagBuilderMixin"

fabric-data-generation-api-v1/src/main/resources/fabric.mod.json

@@ -28,6 +28,9 @@
   ],
   "accessWidener" : "fabric-data-generation-api-v1.accesswidener",
   "custom": {
-    "fabric-api:module-lifecycle": "stable"
+    "fabric-api:module-lifecycle": "stable",
+    "loom:injected_interfaces": {
+      "net/minecraft/class_7788": ["net/fabricmc/fabric/api/datagen/v1/loot/FabricBlockLootTableGenerator"]
+    }
   }
 }

fabric-data-generation-api-v1/src/testmod/java/net/fabricmc/fabric/test/datagen/DataGeneratorTestEntrypoint.java

@@ -249,7 +249,8 @@ private TestBlockLootTableProvider(FabricDataOutput output) {
 
 		@Override
 		public void generate() {
-			addDrop(SIMPLE_BLOCK);
+			// Same condition twice to test recursive condition adding
+			withConditions(ALWAYS_LOADED).withConditions(DefaultResourceConditions.not(NEVER_LOADED)).addDrop(SIMPLE_BLOCK);
 			addDrop(BLOCK_WITHOUT_ITEM, drops(SIMPLE_BLOCK));
 
 			excludeFromStrictValidation(BLOCK_WITHOUT_LOOT_TABLE);