Refactor SubChunk to use non-nullable block and liquid layers

- Changed SubChunk constructor to accept null for layers and initialize empty PalettedBlockArray internally
- Updated all SubChunk getters to return non-nullable PalettedBlockArray
- Modified serialization/deserialization logic to check for layer emptiness instead of null
- Updated all SubChunk constructor calls across codebase to pass null for empty layers
- Simplified code by removing unnecessary null checks throughout the codebase
- Updated tests to match new SubChunk API

src/world/format/SubChunk.php

@@ -31,17 +31,31 @@ class SubChunk{
 	public const COORD_MASK = ~(~0 << self::COORD_BIT_SIZE);
 	public const EDGE_LENGTH = 1 << self::COORD_BIT_SIZE;
 
+	private int $emptyBlockId;
+	private PalettedBlockArray $blockLayer;
+	private PalettedBlockArray $liquidLayer;
+	private PalettedBlockArray $biomes;
+	private ?LightArray $skyLight;
+	private ?LightArray $blockLight;
+
 	/**
 	 * SubChunk constructor.
 	 */
 	public function __construct(
-		private int $emptyBlockId,
+		int $emptyBlockId,
-		private ?PalettedBlockArray $blockLayer,
+		?PalettedBlockArray $blockLayer,
-		private ?PalettedBlockArray $liquidLayer,
+		?PalettedBlockArray $liquidLayer,
-		private PalettedBlockArray $biomes,
+		PalettedBlockArray $biomes,
-		private ?LightArray $skyLight = null,
+		?LightArray $skyLight = null,
-		private ?LightArray $blockLight = null
+		?LightArray $blockLight = null
-	){}
+	){
+		$this->emptyBlockId = $emptyBlockId;
+		$this->blockLayer = $blockLayer ?? new PalettedBlockArray($emptyBlockId);
+		$this->liquidLayer = $liquidLayer ?? new PalettedBlockArray($emptyBlockId);
+		$this->biomes = $biomes;
+		$this->skyLight = $skyLight;
+		$this->blockLight = $blockLight;
+	}
 
 	/**
 	 * Returns whether this subchunk contains any non-air blocks.
@@ -58,7 +72,8 @@ class SubChunk{
 	 * This may report non-empty erroneously if the chunk has been modified and not garbage-collected.
 	 */
 	public function isEmptyFast() : bool{
-		return $this->blockLayer === null && $this->liquidLayer === null;
+		return $this->blockLayer->getBitsPerBlock() === 0 && $this->blockLayer->get(0, 0, 0) === $this->emptyBlockId &&
+			   $this->liquidLayer->getBitsPerBlock() === 0 && $this->liquidLayer->get(0, 0, 0) === $this->emptyBlockId;
 	}
 
 	/**
@@ -68,16 +83,10 @@ class SubChunk{
 	public function getEmptyBlockId() : int{ return $this->emptyBlockId; }
 
 	public function getBlockStateId(int $x, int $y, int $z) : int{
-		if($this->blockLayer === null){
-			return $this->emptyBlockId;
-		}
 		return $this->blockLayer->get($x, $y, $z);
 	}
 
 	public function setBlockStateId(int $x, int $y, int $z, int $block) : void{
-		if($this->blockLayer === null){
-			$this->blockLayer = new PalettedBlockArray($this->emptyBlockId);
-		}
 		$this->blockLayer->set($x, $y, $z, $block);
 	}
 
@@ -87,36 +96,26 @@ class SubChunk{
 	 * @phpstan-return list<PalettedBlockArray>
 	 */
 	public function getBlockLayers() : array{
-		$layers = [];
+		return [$this->blockLayer, $this->liquidLayer];
-		if($this->blockLayer !== null){
-			$layers[] = $this->blockLayer;
-		}
-		if($this->liquidLayer !== null){
-			$layers[] = $this->liquidLayer;
-		}
-		return $layers;
 	}
 
-	public function getBlockLayer() : ?PalettedBlockArray{
+	public function getBlockLayer() : PalettedBlockArray{
 		return $this->blockLayer;
 	}
 
-	public function setBlockLayer(?PalettedBlockArray $blockLayer) : void{
+	public function setBlockLayer(PalettedBlockArray $blockLayer) : void{
 		$this->blockLayer = $blockLayer;
 	}
 
-	public function getLiquidLayer() : ?PalettedBlockArray{
+	public function getLiquidLayer() : PalettedBlockArray{
 		return $this->liquidLayer;
 	}
 
-	public function setLiquidLayer(?PalettedBlockArray $liquidLayer) : void{
+	public function setLiquidLayer(PalettedBlockArray $liquidLayer) : void{
 		$this->liquidLayer = $liquidLayer;
 	}
 
 	public function getHighestBlockAt(int $x, int $z) : ?int{
-		if($this->blockLayer === null){
-			return null;
-		}
 		for($y = self::EDGE_LENGTH - 1; $y >= 0; --$y){
 			if($this->blockLayer->get($x, $y, $z) !== $this->emptyBlockId){
 				return $y;
@@ -152,18 +151,8 @@ class SubChunk{
 	}
 
 	public function collectGarbage() : void{
-		if($this->blockLayer !== null){
 		$this->blockLayer->collectGarbage();
-			if($this->blockLayer->getBitsPerBlock() === 0 && $this->blockLayer->get(0, 0, 0) === $this->emptyBlockId){
-				$this->blockLayer = null;
-			}
-		}
-		if($this->liquidLayer !== null){
 		$this->liquidLayer->collectGarbage();
-			if($this->liquidLayer->getBitsPerBlock() === 0 && $this->liquidLayer->get(0, 0, 0) === $this->emptyBlockId){
-				$this->liquidLayer = null;
-			}
-		}
 		$this->biomes->collectGarbage();
 
 		if($this->skyLight !== null && $this->skyLight->isUniform(0)){
@@ -175,12 +164,8 @@ class SubChunk{
 	}
 
 	public function __clone(){
-		if($this->blockLayer !== null){
 		$this->blockLayer = clone $this->blockLayer;
-		}
-		if($this->liquidLayer !== null){
 		$this->liquidLayer = clone $this->liquidLayer;
-		}
 		$this->biomes = clone $this->biomes;
 
 		if($this->skyLight !== null){

src/world/format/io/FastChunkSerializer.php

@@ -75,22 +75,10 @@ final class FastChunkSerializer{
 			$stream->putByte($y);
 			$stream->putInt($subChunk->getEmptyBlockId());
 			
-			// Write block layer presence and data
+			// Write block and liquid layers (always present)
-			$blockLayer = $subChunk->getBlockLayer();
+			self::serializePalettedArray($stream, $subChunk->getBlockLayer());
-			$stream->putByte($blockLayer !== null ? 1 : 0);
+			self::serializePalettedArray($stream, $subChunk->getLiquidLayer());
-			if($blockLayer !== null){
-				self::serializePalettedArray($stream, $blockLayer);
-			}
-			
-			// Write liquid layer presence and data
-			$liquidLayer = $subChunk->getLiquidLayer();
-			$stream->putByte($liquidLayer !== null ? 1 : 0);
-			if($liquidLayer !== null){
-				self::serializePalettedArray($stream, $liquidLayer);
-			}
-			
 			self::serializePalettedArray($stream, $subChunk->getBiomeArray());
-
 		}
 
 		return $stream->getBuffer();
@@ -122,19 +110,11 @@ final class FastChunkSerializer{
 			$y = Binary::signByte($stream->getByte());
 			$airBlockId = $stream->getInt();
 
-			// Read block layer
+			// Read block and liquid layers (always present)
-			$blockLayer = null;
-			if($stream->getByte() !== 0){
 			$blockLayer = self::deserializePalettedArray($stream);
-			}
-			
-			// Read liquid layer
-			$liquidLayer = null;
-			if($stream->getByte() !== 0){
 			$liquidLayer = self::deserializePalettedArray($stream);
-			}
-			
 			$biomeArray = self::deserializePalettedArray($stream);
+			
 			$subChunks[$y] = new SubChunk($airBlockId, $blockLayer, $liquidLayer, $biomeArray);
 		}