feat: Add isStackable utility method (#11)

* feat: Add `isStackable` utility method * feat: Add convenience methods for EntityRef and Prefab * chore: Use `isStackable` instead of computing it manually
Terasology · May 23, 2020 · 9251201 · 9251201
1 parent 3715692
commit 9251201
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Showing 4 changed files with 59 additions and 22 deletions.
diff --git a/src/main/java/org/terasology/logic/inventory/InventoryUtils.java b/src/main/java/org/terasology/logic/inventory/InventoryUtils.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MovingBlocks
+ * Copyright 2020 MovingBlocks
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 
 import org.terasology.entitySystem.Component;
 import org.terasology.entitySystem.entity.EntityRef;
+import org.terasology.entitySystem.prefab.Prefab;
 import org.terasology.logic.inventory.events.BeforeItemPutInInventory;
 import org.terasology.logic.inventory.events.BeforeItemRemovedFromInventory;
 import org.terasology.logic.inventory.events.InventorySlotChangedEvent;
@@ -91,15 +92,7 @@ public static boolean isSameItem(EntityRef item1, EntityRef item2) {
             return false;
         }
 
-        if (!isSameStackId(itemComp1, itemComp2)) {
-            return false;
-        }
-
-        if (!hasSameAttributes(item1, item2)) {
-            return false;
-        }
-
-        return true;
+        return isSameStackId(itemComp1, itemComp2) && hasSameAttributes(item1, item2);
     }
 
     private static boolean hasSameAttributes(EntityRef from, EntityRef to) {
@@ -135,12 +128,59 @@ private static boolean hasSameAttributes(EntityRef from, EntityRef to) {
         return true;
     }
 
-    private static boolean isSameStackId(ItemComponent item1, ItemComponent item2) {
-        if (item1.stackId == null || item1.stackId.isEmpty() || item2.stackId == null || item2.stackId.isEmpty()) {
-            return false;
-        }
+    /**
+     * Determine whether an {@link EntityRef} denotes a stackable item.
+     * <p>
+     * An entity describes a stackable item iff it has an {@link ItemComponent} for which {@link
+     * #isStackable(ItemComponent)} holds.
+     *
+     * @param entity the entity to check whether it describes a stackable item
+     * @return true iff the entity has an item component which is stackable
+     */
+    public static boolean isStackable(EntityRef entity) {
+        return isStackable(entity.getComponent(ItemComponent.class));
+    }
 
-        return item1.stackId.equals(item2.stackId);
+    /**
+     * Determine whether a {@link Prefab} is a stackable item.
+     * <p>
+     * A prefab describes a stackable item iff it has an {@link ItemComponent} for which {@link
+     * #isStackable(ItemComponent)} holds.
+     *
+     * @param prefab the prefab to check whether it describes a stackable item
+     * @return true iff the prefab has an item component which is stackable
+     */
+    public static boolean isStackable(Prefab prefab) {
+        return isStackable(prefab.getComponent(ItemComponent.class));
+    }
+
+    /**
+     * Determine whether an {@link ItemComponent} is stackable or not.
+     * <p>
+     * An item is <emph>stackable</emph> iff it has a non-empty {@link ItemComponent#stackId} and a {@link
+     * ItemComponent#maxStackSize} greater than one.
+     *
+     * @param item the item to check whether it is stackable
+     * @return true iff the item exists and is stackable
+     */
+    public static boolean isStackable(ItemComponent item) {
+        return hasStackId(item) && item.maxStackSize > 1;
+    }
+
+    /**
+     * Determine whether an item has a non-empty {@link ItemComponent#stackId}.
+     * <p>
+     * A non-empty stack id is a necessity for an item to be stackable.
+     *
+     * @param item the item to check for a non-empty stack id
+     * @return true iff the item exists and has a non-empty stack id
+     */
+    private static boolean hasStackId(ItemComponent item) {
+        return item != null && item.stackId != null && !item.stackId.isEmpty();
+    }
+
+    private static boolean isSameStackId(ItemComponent item1, ItemComponent item2) {
+        return hasStackId(item1) && hasStackId(item2) && item1.stackId.equals(item2.stackId);
     }
 
     private static boolean validateMove(EntityRef instigator, EntityRef from, int slotFrom, EntityRef to, int slotTo) {

diff --git a/src/main/java/org/terasology/logic/inventory/ItemCommands.java b/src/main/java/org/terasology/logic/inventory/ItemCommands.java
@@ -44,11 +44,8 @@
 import org.terasology.world.block.loader.BlockFamilyDefinition;
 import org.terasology.world.block.shapes.BlockShape;
 
-import java.util.ArrayList;
 import java.util.Collections;
-import java.util.Iterator;
 import java.util.List;
-import java.util.Optional;
 import java.util.Set;
 
 @RegisterSystem
@@ -315,7 +312,7 @@ private int removeItem(Prefab prefab, String displayName, final int removalQuant
             if (slotPrefab != null && slotPrefab.equals(prefab)) {
                 quantityLeft = removeObjectFromSlot(slot,
                         playerEntity,
-                        !prefab.getComponent(ItemComponent.class).stackId.isEmpty(),
+                        InventoryUtils.isStackable(prefab),
                         displayName,
                         quantityLeft);
 
@@ -353,4 +350,4 @@ private int removeBlock(BlockFamily blockFamily, String displayName, final int r
 
         return removalQuantity - quantityLeft;
     }
-}
+}
diff --git a/src/main/java/org/terasology/logic/inventory/StartingInventorySystem.java b/src/main/java/org/terasology/logic/inventory/StartingInventorySystem.java
@@ -137,7 +137,7 @@ private boolean tryAddItems(EntityRef entityRef,
             logger.error("Failed to find ItemComponent for {}", uri);
             return false;
         }
-        if (component.stackId == null || component.stackId.length() == 0) {
+        if (!InventoryUtils.isStackable(component)) {
             // Item is not stackable, one slot used per item
             if (available >= quantity) {
                 for (int i = 0; i < quantity; ++i) {

diff --git a/src/main/java/org/terasology/logic/inventory/block/BlockInventorySystem.java b/src/main/java/org/terasology/logic/inventory/block/BlockInventorySystem.java
@@ -55,7 +55,7 @@ public void copyBlockInventory(OnBlockToItem event, EntityRef blockEntity) {
             inventoryManager.switchItem(blockEntity, blockEntity, i, inventoryItem, i);
         }
         ItemComponent itemComponent = inventoryItem.getComponent(ItemComponent.class);
-        if (itemComponent != null && !itemComponent.stackId.isEmpty()) {
+        if (InventoryUtils.isStackable(itemComponent)) {
             itemComponent.stackId = "";
             inventoryItem.saveComponent(itemComponent);
         }