Add GatherComponentsEvent (#9944)

build_forge.gradle

@@ -180,6 +180,7 @@ patcher {
 
         forge_client_test {
             parent runs.forge_client
+            source sourceSets.test
         }
 
         forge_server {
@@ -188,6 +189,7 @@ patcher {
 
         forge_server_test {
             parent runs.forge_server
+            source sourceSets.test
         }
 
         forge_server_gametest {
@@ -196,6 +198,7 @@ patcher {
 
         forge_server_gametest_test {
             parent runs.forge_server_gametest
+            source sourceSets.test
         }
 
         forge_data {

patches/minecraft/net/minecraft/world/item/Item.java.patch

@@ -23,7 +23,27 @@
      }
 
      @Deprecated
-@@ -111,6 +_,7 @@
+@@ -100,17 +_,25 @@
+         return this.builtInRegistryHolder;
+     }
+
++    @Nullable
++    private DataComponentMap builtComponents = null;
++
+     public DataComponentMap components() {
+-        return this.components;
++        if (builtComponents == null) {
++            builtComponents = net.minecraftforge.common.ForgeHooks.gatherItemComponents(this, components);
++        }
++
++        return builtComponents;
+     }
+
+     public int getDefaultMaxStackSize() {
+-        return this.components.getOrDefault(DataComponents.MAX_STACK_SIZE, 1);
++        return builtComponents == null ? this.components.getOrDefault(DataComponents.MAX_STACK_SIZE, 1) : this.builtComponents.getOrDefault(DataComponents.MAX_STACK_SIZE, 1);
+     }
+
      public void onUseTick(Level p_41428_, LivingEntity p_41429_, ItemStack p_41430_, int p_41431_) {
      }
 

src/main/java/net/minecraftforge/common/ForgeHooks.java

@@ -49,6 +49,7 @@
 import net.minecraft.core.HolderLookup;
 import net.minecraft.core.HolderSet;
 import net.minecraft.core.NonNullList;
+import net.minecraft.core.component.DataComponentMap;
 import net.minecraft.core.component.DataComponents;
 import net.minecraft.core.particles.ParticleTypes;
 import net.minecraft.network.Connection;
@@ -130,6 +131,7 @@
 import net.minecraftforge.event.AnvilUpdateEvent;
 import net.minecraftforge.event.BuildCreativeModeTabContentsEvent;
 import net.minecraftforge.event.ForgeEventFactory;
+import net.minecraftforge.event.GatherComponentsEvent;
 import net.minecraftforge.event.GrindstoneEvent;
 import net.minecraftforge.event.ModMismatchEvent;
 import net.minecraftforge.event.ServerChatEvent;
@@ -1299,4 +1301,8 @@ public static DyeColor getDyeColorFromItemStack(ItemStack stack) {
 
         return null;
     }
+
+    public static DataComponentMap gatherItemComponents(Item item, DataComponentMap dataComponents) {
+        return DataComponentMap.composite(dataComponents, ForgeEventFactory.gatherItemComponentsEvent(item, dataComponents).getDataComponentMap());
+    }
 }

src/main/java/net/minecraftforge/event/ForgeEventFactory.java

@@ -14,6 +14,8 @@
 import java.util.function.BooleanSupplier;
 import java.util.function.Consumer;
 
+import net.minecraft.core.component.DataComponentMap;
+import net.minecraft.world.item.Item;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.eventbus.api.Cancelable;
 import net.minecraftforge.eventbus.api.Event;
@@ -1088,4 +1090,8 @@ public static AnvilRepairEvent onAnvilRepair(Player player, @NotNull ItemStack o
     public static void onPlayerTradeWithVillager(Player player, MerchantOffer offer, AbstractVillager villager) {
         post(new TradeWithVillagerEvent(player, offer, villager));
     }
+
+    public static GatherComponentsEvent.Item gatherItemComponentsEvent(Item item, DataComponentMap dataComponents) {
+        return fire(new GatherComponentsEvent.Item(item, dataComponents));
+    }
 }

src/main/java/net/minecraftforge/event/GatherComponentsEvent.java

@@ -0,0 +1,62 @@
+package net.minecraftforge.event;
+
+import net.minecraft.core.component.DataComponentMap;
+import net.minecraft.core.component.DataComponentType;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.world.item.Item;
+import net.minecraftforge.eventbus.api.Event;
+import org.jetbrains.annotations.ApiStatus;
+
+import javax.annotation.Nullable;
+
+/**
+ Where all the events fore Gathering Components will exist.
+ */
+
+public abstract class GatherComponentsEvent extends Event {
+    private final DataComponentMap.Builder components = DataComponentMap.builder();
+    private final DataComponentMap originalComponents;
+    private final Object owner;
+
+    protected GatherComponentsEvent(Object owner, DataComponentMap originalComponents) {
+        this.originalComponents = originalComponents;
+        this.owner = owner;
+    }
+
+    public <T> void register(DataComponentType<T> componentType, @Nullable T value) {
+        components.set(componentType, value);
+    }
+
+    @ApiStatus.Internal
+    public DataComponentMap getDataComponentMap() {
+        return components.build();
+    }
+
+    public DataComponentMap getOriginalComponentMap() {
+        return originalComponents;
+    }
+
+    public Object getOwner() {
+        return owner;
+    }
+
+    /**
+     * Used to get additional Components for any {@link net.minecraft.world.item.Item}
+     *
+     * Fired once for every {@link net.minecraft.world.item.Item} instance, only once, Lazily.
+     *
+     * Recursion is not supported. Cant call {@link net.minecraft.world.item.Item#components()} as that would cause a loop.
+     *
+     * References in {@link net.minecraft.world.item.Items} may not be valid at the current time.
+     */
+    public static class Item extends GatherComponentsEvent {
+        public Item(net.minecraft.world.item.Item item, DataComponentMap dataComponents) {
+            super(item, dataComponents);
+        }
+
+        @Override
+        public net.minecraft.world.item.Item getOwner() {
+            return (net.minecraft.world.item.Item) super.getOwner();
+        }
+    }
+}

src/test/java/net/minecraftforge/debug/gameplay/item/GatherComponentsEventTest.java

@@ -0,0 +1,45 @@
+package net.minecraftforge.debug.gameplay.item;
+
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.gametest.framework.GameTest;
+import net.minecraft.gametest.framework.GameTestHelper;
+import net.minecraft.world.food.FoodProperties;
+import net.minecraft.world.item.Items;
+import net.minecraftforge.common.MinecraftForge;
+import net.minecraftforge.event.GatherComponentsEvent;
+import net.minecraftforge.eventbus.api.IEventBus;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.gametest.GameTestHolder;
+import net.minecraftforge.test.BaseTestMod;
+
+import java.util.List;
+
+@GameTestHolder("forge." + GatherComponentsEventTest.MOD_ID)
+@Mod(GatherComponentsEventTest.MOD_ID)
+public class GatherComponentsEventTest extends BaseTestMod {
+    public static final String MOD_ID = "gather_components_test_event";
+
+    public GatherComponentsEventTest() {
+        IEventBus bus = MinecraftForge.EVENT_BUS;
+        bus.addListener(this::onItem);
+    }
+
+    public void onItem(GatherComponentsEvent.Item itemEvent) {
+        if (!itemEvent.getOriginalComponentMap().has(DataComponents.FOOD) && itemEvent.getOwner() == Items.IRON_NUGGET) {
+            itemEvent.register(DataComponents.FOOD, new FoodProperties(
+                    2,
+                    7,
+                    true,
+                    3,
+                    List.of()
+            ));
+        }
+    }
+
+    @GameTest(template = "forge:empty3x3x3")
+    public static void onTestForFood(GameTestHelper helper) {
+        helper.assertTrue(Items.IRON_NUGGET.components().has(DataComponents.FOOD), "Iron Nugget is not edible, failed to apply DataComponents.FOOD to it.");
+        helper.assertFalse(Items.IRON_INGOT.components().has(DataComponents.FOOD), "Iron Ingot is edible, should not have DataComponents.FOOD");
+        helper.succeed();
+    }
+}