minecraft-src/net/minecraft/world/entity/SlotAccess.java

package net.minecraft.world.entity;

import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.Supplier;
import net.minecraft.world.Container;
import net.minecraft.world.item.ItemStack;

public interface SlotAccess {
	SlotAccess NULL = new SlotAccess() {
		@Override
		public ItemStack get() {
			return ItemStack.EMPTY;
		}

		@Override
		public boolean set(ItemStack carried) {
			return false;
		}
	};

	static SlotAccess of(Supplier<ItemStack> getter, Consumer<ItemStack> setter) {
		return new SlotAccess() {
			@Override
			public ItemStack get() {
				return (ItemStack)getter.get();
			}

			@Override
			public boolean set(ItemStack carried) {
				setter.accept(carried);
				return true;
			}
		};
	}

	static SlotAccess forContainer(Container inventory, int slot, Predicate<ItemStack> stackFilter) {
		return new SlotAccess() {
			@Override
			public ItemStack get() {
				return inventory.getItem(slot);
			}

			@Override
			public boolean set(ItemStack carried) {
				if (!stackFilter.test(carried)) {
					return false;
				} else {
					inventory.setItem(slot, carried);
					return true;
				}
			}
		};
	}

	static SlotAccess forContainer(Container inventory, int slot) {
		return forContainer(inventory, slot, itemStack -> true);
	}

	static SlotAccess forEquipmentSlot(LivingEntity entity, EquipmentSlot slot, Predicate<ItemStack> stackFilter) {
		return new SlotAccess() {
			@Override
			public ItemStack get() {
				return entity.getItemBySlot(slot);
			}

			@Override
			public boolean set(ItemStack carried) {
				if (!stackFilter.test(carried)) {
					return false;
				} else {
					entity.setItemSlot(slot, carried);
					return true;
				}
			}
		};
	}

	static SlotAccess forEquipmentSlot(LivingEntity entity, EquipmentSlot slot) {
		return forEquipmentSlot(entity, slot, itemStack -> true);
	}

	ItemStack get();

	boolean set(ItemStack carried);
}