Added ItemFactory::air() sugar

This makes it easier to create air stacks without accidents, and also reduces the amount of throwaway air objects which get created.

src/pocketmine/inventory/BaseInventory.php

@@ -95,7 +95,7 @@ abstract class BaseInventory implements Inventory{
 	}
 
 	public function getItem(int $index) : Item{
-		return $this->slots[$index] !== null ? clone $this->slots[$index] : ItemFactory::get(Item::AIR, 0, 0);
+		return $this->slots[$index] !== null ? clone $this->slots[$index] : ItemFactory::air();
 	}
 
 	/**
@@ -105,13 +105,12 @@ abstract class BaseInventory implements Inventory{
 	 */
 	public function getContents(bool $includeEmpty = false) : array{
 		$contents = [];
-		$air = null;
 
 		foreach($this->slots as $i => $slot){
 			if($slot !== null){
 				$contents[$i] = clone $slot;
 			}elseif($includeEmpty){
-				$contents[$i] = $air ?? ($air = ItemFactory::get(Item::AIR, 0, 0));
+				$contents[$i] = ItemFactory::air();
 			}
 		}
 
@@ -146,7 +145,7 @@ abstract class BaseInventory implements Inventory{
 
 	public function setItem(int $index, Item $item, bool $send = true) : bool{
 		if($item->isNull()){
-			$item = ItemFactory::get(Item::AIR, 0, 0);
+			$item = ItemFactory::air();
 		}else{
 			$item = clone $item;
 		}
@@ -351,7 +350,7 @@ abstract class BaseInventory implements Inventory{
 	}
 
 	public function clear(int $index, bool $send = true) : bool{
-		return $this->setItem($index, ItemFactory::get(Item::AIR, 0, 0), $send);
+		return $this->setItem($index, ItemFactory::air(), $send);
 	}
 
 	public function clearAll(bool $send = true) : void{

src/pocketmine/inventory/ShapedRecipe.php

@@ -176,7 +176,7 @@ class ShapedRecipe implements CraftingRecipe{
 	 */
 	public function getIngredient(int $x, int $y) : Item{
 		$exists = $this->ingredientList[$this->shape[$y]{$x}] ?? null;
-		return $exists !== null ? clone $exists : ItemFactory::get(Item::AIR, 0, 0);
+		return $exists !== null ? clone $exists : ItemFactory::air();
 	}
 
 	/**

src/pocketmine/inventory/transaction/action/DropItemAction.php

@@ -34,7 +34,7 @@ use pocketmine\Player;
 class DropItemAction extends InventoryAction{
 
 	public function __construct(Item $targetItem){
-		parent::__construct(ItemFactory::get(Item::AIR, 0, 0), $targetItem);
+		parent::__construct(ItemFactory::air(), $targetItem);
 	}
 
 	public function isValid(Player $source) : bool{

src/pocketmine/item/FlintSteel.php

@@ -36,7 +36,7 @@ class FlintSteel extends Tool{
 	}
 
 	public function onActivate(Player $player, Block $blockReplace, Block $blockClicked, int $face, Vector3 $clickVector) : ItemUseResult{
-		if($blockReplace->getId() === self::AIR){
+		if($blockReplace->getId() === Block::AIR){
 			$level = $player->getLevel();
 			assert($level !== null);
 			$level->setBlock($blockReplace, BlockFactory::get(Block::FIRE));

src/pocketmine/item/Food.php

@@ -34,7 +34,7 @@ abstract class Food extends Item implements FoodSource{
 	 * @return Item
 	 */
 	public function getResidue(){
-		return ItemFactory::get(Item::AIR, 0, 0);
+		return ItemFactory::air();
 	}
 
 	public function getAdditionalEffects() : array{

src/pocketmine/item/Item.php

@@ -640,7 +640,7 @@ class Item implements ItemIds, \JsonSerializable{
 	 * @return Block
 	 */
 	public function getBlock() : Block{
-		return BlockFactory::get(self::AIR);
+		return BlockFactory::get(Block::AIR);
 	}
 
 	/**
@@ -939,7 +939,7 @@ class Item implements ItemIds, \JsonSerializable{
 				$item = ItemFactory::fromString($idTag->getValue() . ":$meta");
 			}catch(\InvalidArgumentException $e){
 				//TODO: improve error handling
-				return ItemFactory::get(Item::AIR, 0, 0);
+				return ItemFactory::air();
 			}
 			$item->setCount($count);
 		}else{

src/pocketmine/item/ItemFactory.php

@@ -47,6 +47,9 @@ class ItemFactory{
 	/** @var \SplFixedArray */
 	private static $list = [];
 
+	/** @var Item|null */
+	private static $air = null;
+
 	public static function init(){
 		self::$list = []; //in case of re-initializing
 
@@ -423,6 +426,10 @@ class ItemFactory{
 		return $item;
 	}
 
+	public static function air() : Item{
+		return self::$air ?? (self::$air = self::get(ItemIds::AIR, 0, 0));
+	}
+
 	/**
 	 * Returns whether the specified item ID is already registered in the item factory.
 	 *

src/pocketmine/level/Explosion.php

@@ -32,7 +32,6 @@ use pocketmine\event\entity\EntityDamageByBlockEvent;
 use pocketmine\event\entity\EntityDamageByEntityEvent;
 use pocketmine\event\entity\EntityDamageEvent;
 use pocketmine\event\entity\EntityExplodeEvent;
-use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\level\particle\HugeExplodeSeedParticle;
 use pocketmine\level\utils\SubChunkIteratorManager;
@@ -199,7 +198,7 @@ class Explosion{
 		}
 
 
-		$air = ItemFactory::get(Item::AIR);
+		$air = ItemFactory::air();
 		$airBlock = BlockFactory::get(Block::AIR);
 
 		foreach($this->affectedBlocks as $block){

src/pocketmine/level/Level.php

@@ -1674,7 +1674,7 @@ class Level implements ChunkManager, Metadatable{
 		$affectedBlocks = $target->getAffectedBlocks();
 
 		if($item === null){
-			$item = ItemFactory::get(Item::AIR, 0, 0);
+			$item = ItemFactory::air();
 		}
 
 		$drops = [];

src/pocketmine/level/particle/FloatingTextParticle.php

@@ -26,7 +26,6 @@ namespace pocketmine\level\particle;
 use pocketmine\entity\Entity;
 use pocketmine\entity\EntityFactory;
 use pocketmine\entity\Skin;
-use pocketmine\item\Item;
 use pocketmine\item\ItemFactory;
 use pocketmine\math\Vector3;
 use pocketmine\network\mcpe\protocol\AddPlayerPacket;
@@ -103,7 +102,7 @@ class FloatingTextParticle implements Particle{
 			$pk->username = $name;
 			$pk->entityRuntimeId = $this->entityId;
 			$pk->position = $pos; //TODO: check offset
-			$pk->item = ItemFactory::get(Item::AIR, 0, 0);
+			$pk->item = ItemFactory::air();
 
 			$flags = (
 				1 << Entity::DATA_FLAG_IMMOBILE

src/pocketmine/tile/FlowerPot.php

@@ -39,7 +39,7 @@ class FlowerPot extends Spawnable{
 	private $item;
 
 	public function __construct(Level $level, Vector3 $pos){
-		$this->item = ItemFactory::get(Item::AIR, 0, 0);
+		$this->item = ItemFactory::air();
 		parent::__construct($level, $pos);
 	}
 
@@ -87,7 +87,7 @@ class FlowerPot extends Spawnable{
 	}
 
 	public function removeItem(){
-		$this->setItem(ItemFactory::get(Item::AIR, 0, 0));
+		$this->setItem(ItemFactory::air());
 	}
 
 	public function isEmpty() : bool{

src/pocketmine/tile/ItemFrame.php

@@ -42,7 +42,7 @@ class ItemFrame extends Spawnable{
 	private $itemDropChance = 1.0;
 
 	public function __construct(Level $level, Vector3 $pos){
-		$this->item = ItemFactory::get(Item::AIR, 0, 0);
+		$this->item = ItemFactory::air();
 		parent::__construct($level, $pos);
 	}
 
@@ -72,7 +72,7 @@ class ItemFrame extends Spawnable{
 		if($item !== null and !$item->isNull()){
 			$this->item = clone $item;
 		}else{
-			$this->item = ItemFactory::get(Item::AIR, 0, 0);
+			$this->item = ItemFactory::air();
 		}
 		$this->onChanged();
 	}