start making network compressors dynamic

this will facilitate future multi version support where compression types are different between versions

src/network/mcpe/compression/ZlibCompressor.php

@@ -0,0 +1,77 @@
+<?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\network\mcpe\compression;
+
+use pocketmine\utils\SingletonTrait;
+use function strlen;
+use function zlib_decode;
+use function zlib_encode;
+use const ZLIB_ENCODING_DEFLATE;
+
+final class ZlibCompressor{
+	use SingletonTrait;
+
+	public const DEFAULT_LEVEL = 7;
+	public const DEFAULT_THRESHOLD = 256;
+	public const DEFAULT_MAX_DECOMPRESSION_SIZE = 2 * 1024 * 1024;
+
+	/**
+	 * @see SingletonTrait::make()
+	 */
+	private static function make() : self{
+		return new self(self::DEFAULT_LEVEL, self::DEFAULT_THRESHOLD, self::DEFAULT_MAX_DECOMPRESSION_SIZE);
+	}
+
+	/** @var int */
+	private $level;
+	/** @var int */
+	private $threshold;
+	/** @var int */
+	private $maxDecompressionSize;
+
+	public function __construct(int $level, int $minCompressionSize, int $maxDecompressionSize){
+		$this->level = $level;
+		$this->threshold = $minCompressionSize;
+		$this->maxDecompressionSize = $maxDecompressionSize;
+	}
+
+	public function willCompress(string $data) : bool{
+		return $this->threshold > -1 and strlen($data) >= $this->threshold;
+	}
+
+	/**
+	 * @throws DecompressionException
+	 */
+	public function decompress(string $payload) : string{
+		$result = @zlib_decode($payload, $this->maxDecompressionSize);
+		if($result === false){
+			throw new DecompressionException("Failed to decompress data");
+		}
+		return $result;
+	}
+
+	public function compress(string $payload) : string{
+		return zlib_encode($payload, ZLIB_ENCODING_DEFLATE, $this->willCompress($payload) ? $this->level : 0);
+	}
+}