refactor for inventories, allowing for null types.

src/main/java/carpet/script/utils/EquipmentInventory.java

@@ -0,0 +1,126 @@
+package carpet.script.utils;
+
+import net.minecraft.entity.EquipmentSlot;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.inventory.Inventory;
+import net.minecraft.item.ItemStack;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class EquipmentInventory implements Inventory
+{
+    private static final List<EquipmentSlot> slotToSlot = Arrays.asList(
+            EquipmentSlot.MAINHAND,
+            EquipmentSlot.FEET, EquipmentSlot.LEGS, EquipmentSlot.CHEST, EquipmentSlot.HEAD,
+            EquipmentSlot.OFFHAND
+    );
+
+    LivingEntity mob;
+    public EquipmentInventory(LivingEntity mob)
+    {
+        this.mob = mob;
+    }
+
+    @Override
+    public int size()
+    {
+        return 6;
+    }
+
+    @Override
+    public boolean isEmpty()
+    {
+        for (EquipmentSlot slot: slotToSlot)
+            if (!mob.getEquippedStack(slot).isEmpty()) return false;
+        return true;
+    }
+
+    @Override
+    public ItemStack getStack(int slot)
+    {
+        EquipmentSlot slotSlot;
+        try
+        {
+            slotSlot = slotToSlot.get(slot);
+        }
+        catch (IndexOutOfBoundsException ignored)
+        {
+            //going out of the index should be really exceptional
+            return null;
+        }
+        return mob.getEquippedStack(slotSlot);
+    }
+
+    @Override
+    public ItemStack removeStack(int slot, int amount)
+    {
+        EquipmentSlot slotSlot;
+        try
+        {
+            slotSlot = slotToSlot.get(slot);
+        }
+        catch (IndexOutOfBoundsException ignored)
+        {
+            //going out of the index should be really exceptional
+            return null;
+        }
+        ItemStack stack = mob.getEquippedStack(slotSlot);
+        stack.decrement(amount);
+        return stack;
+    }
+
+    @Override
+    public ItemStack removeStack(int slot)
+    {
+        EquipmentSlot slotSlot;
+        try
+        {
+            slotSlot = slotToSlot.get(slot);
+        }
+        catch (IndexOutOfBoundsException ignored)
+        {
+            //going out of the index should be really exceptional
+            return null;
+        }
+        ItemStack previous = mob.getEquippedStack(slotSlot);
+        mob.equipStack(slotSlot, ItemStack.EMPTY);
+        return previous;
+    }
+
+    @Override
+    public void setStack(int slot, ItemStack stack)
+    {
+        EquipmentSlot slotSlot;
+        try
+        {
+            slotSlot = slotToSlot.get(slot);
+        }
+        catch (IndexOutOfBoundsException ignored)
+        {
+            //going out of the index should be really exceptional
+            return;
+        }
+        mob.equipStack(slotSlot, stack);
+    }
+
+    @Override
+    public void markDirty()
+    {
+
+    }
+
+    @Override
+    public boolean canPlayerUse(PlayerEntity player)
+    {
+        return false;
+    }
+
+    @Override
+    public void clear()
+    {
+        for (EquipmentSlot slot: slotToSlot)
+            mob.equipStack(slot, ItemStack.EMPTY);
+    }
+}