Extract a DelegateInventory from EnderChestInventory

src/inventory/DelegateInventory.php

@@ -0,0 +1,78 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\inventory;
+
+use pocketmine\item\Item;
+use pocketmine\player\Player;
+use function count;
+
+/**
+ * An inventory which is backed by another inventory, and acts as a proxy to that inventory.
+ */
+class DelegateInventory extends BaseInventory{
+
+	private Inventory $backingInventory;
+	private InventoryListener $inventoryListener;
+
+	public function __construct(Inventory $backingInventory){
+		parent::__construct();
+		$this->backingInventory = $backingInventory;
+		$this->backingInventory->getListeners()->add($this->inventoryListener = new CallbackInventoryListener(
+			function(Inventory $unused, int $slot, Item $oldItem) : void{
+				$this->onSlotChange($slot, $oldItem);
+			},
+			function(Inventory $unused, array $oldContents) : void{
+				$this->onContentChange($oldContents);
+			}
+		));
+	}
+
+	public function getSize() : int{
+		return $this->backingInventory->getSize();
+	}
+
+	public function getItem(int $index) : Item{
+		return $this->backingInventory->getItem($index);
+	}
+
+	protected function internalSetItem(int $index, Item $item) : void{
+		$this->backingInventory->setItem($index, $item);
+	}
+
+	public function getContents(bool $includeEmpty = false) : array{
+		return $this->backingInventory->getContents($includeEmpty);
+	}
+
+	protected function internalSetContents(array $items) : void{
+		$this->backingInventory->setContents($items);
+	}
+
+	public function onClose(Player $who) : void{
+		parent::onClose($who);
+		if(count($this->getViewers()) === 0 && count($this->getListeners()->toArray()) === 1){
+			$this->backingInventory->getListeners()->remove($this->inventoryListener);
+			$this->inventoryListener = CallbackInventoryListener::onAnyChange(static function() : void{}); //break cyclic reference
+		}
+	}
+}