Add GatherComponentsEvent (#9944)

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

@@ -49,6 +49,7 @@ import net.minecraft.core.Holder;
 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.entity.IEntityAdditionalSpawnData;
 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 final class ForgeHooks {
 
         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.Optional;
 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 final class ForgeEventFactory {
     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();
+        }
+    }
+}