Improve the flexibility of WorldProvider registration

WorldProviders now have the following requirements removed:
- __construct() is no longer required to have a specific signature
- static isValid() no longer needs to be implemented (you will still need it for registering, but it can be declared anywhere now)
- static generate() no longer needs to be implemented

This paves the way for more interesting types of world providers that use something other than local disk to store chunks (e.g. a mysql database).

WorldProviderManager no longer accepts class-string<WorldProvider>. Instead, WorldProviderManagerEntry is required, with 2 or 3 callbacks:
- ReadOnlyWorldProviderManager must provide a callback for isValid, and a callback for fromPath
- WritableWorldProviderManagerEntry must provide the same, and also a generate() callback

In practice, this requires zero changes to the WorldProviders themselves, since a WorldProviderManagerEntry can be created like this:
`new WritableWorldProviderManagerEntry(\Closure::fromCallable([LevelDB::class, 'isValid']), fn(string ) => new LevelDB(), \Closure::fromCallable([LevelDB::class, 'generate']))`

This provides identical functionality to before for the provider itself; only registration is changed.

src/Server.php

@@ -99,7 +99,7 @@ use pocketmine\utils\Terminal;
 use pocketmine\utils\TextFormat;
 use pocketmine\utils\Utils;
 use pocketmine\world\format\io\WorldProviderManager;
-use pocketmine\world\format\io\WritableWorldProvider;
+use pocketmine\world\format\io\WritableWorldProviderManagerEntry;
 use pocketmine\world\generator\Generator;
 use pocketmine\world\generator\GeneratorManager;
 use pocketmine\world\World;
@@ -121,7 +121,6 @@ use function filemtime;
 use function get_class;
 use function implode;
 use function ini_set;
-use function is_a;
 use function is_array;
 use function is_string;
 use function json_decode;
@@ -1014,7 +1013,7 @@ class Server{
 			$providerManager = new WorldProviderManager();
 			if(
 				($format = $providerManager->getProviderByName($formatName = $this->configGroup->getPropertyString("level-settings.default-format", ""))) !== null and
-				is_a($format, WritableWorldProvider::class, true)
+				$format instanceof WritableWorldProviderManagerEntry
 			){
 				$providerManager->setDefault($format);
 			}elseif($formatName !== ""){

src/world/WorldManager.php

@@ -34,7 +34,6 @@ use pocketmine\timings\Timings;
 use pocketmine\world\format\io\exception\CorruptedWorldException;
 use pocketmine\world\format\io\exception\UnsupportedWorldFormatException;
 use pocketmine\world\format\io\FormatConverter;
-use pocketmine\world\format\io\WorldProvider;
 use pocketmine\world\format\io\WorldProviderManager;
 use pocketmine\world\format\io\WritableWorldProvider;
 use pocketmine\world\generator\GeneratorManager;
@@ -205,11 +204,7 @@ class WorldManager{
 		$providerClass = array_shift($providers);
 
 		try{
-			/**
-			 * @var WorldProvider $provider
-			 * @see WorldProvider::__construct()
-			 */
-			$provider = new $providerClass($path);
+			$provider = $providerClass->fromPath($path);
 		}catch(CorruptedWorldException $e){
 			$this->server->getLogger()->error($this->server->getLanguage()->translateString(KnownTranslationKeys::POCKETMINE_LEVEL_LOADERROR, [$name, "Corruption detected: " . $e->getMessage()]));
 			return false;
@@ -255,14 +250,12 @@ class WorldManager{
 			return false;
 		}
 
-		$providerClass = $this->providerManager->getDefault();
+		$providerEntry = $this->providerManager->getDefault();
 
 		$path = $this->getWorldPath($name);
-		/** @var WritableWorldProvider $providerClass */
-		$providerClass::generate($path, $name, $options);
+		$providerEntry->generate($path, $name, $options);
 
-		/** @see WritableWorldProvider::__construct() */
-		$world = new World($this->server, $name, new $providerClass($path), $this->server->getAsyncPool());
+		$world = new World($this->server, $name, $providerEntry->fromPath($path), $this->server->getAsyncPool());
 		$this->worlds[$world->getId()] = $world;
 
 		$world->setAutoSave($this->autoSave);

src/world/format/io/FormatConverter.php

@@ -24,7 +24,6 @@ declare(strict_types=1);
 namespace pocketmine\world\format\io;
 
 use pocketmine\utils\Filesystem;
-use pocketmine\utils\Utils;
 use pocketmine\world\generator\GeneratorManager;
 use pocketmine\world\WorldCreationOptions;
 use Webmozart\PathUtil\Path;
@@ -44,7 +43,7 @@ class FormatConverter{
 
 	/** @var WorldProvider */
 	private $oldProvider;
-	/** @var WritableWorldProvider|string */
+	/** @var WritableWorldProviderManagerEntry */
 	private $newProvider;
 
 	/** @var string */
@@ -56,13 +55,8 @@ class FormatConverter{
 	/** @var int */
 	private $chunksPerProgressUpdate;
 
-	/**
-	 * @phpstan-template TNewProvider of WritableWorldProvider
-	 * @phpstan-param class-string<TNewProvider> $newProvider
-	 */
-	public function __construct(WorldProvider $oldProvider, string $newProvider, string $backupPath, \Logger $logger, int $chunksPerProgressUpdate = 256){
+	public function __construct(WorldProvider $oldProvider, WritableWorldProviderManagerEntry $newProvider, string $backupPath, \Logger $logger, int $chunksPerProgressUpdate = 256){
 		$this->oldProvider = $oldProvider;
-		Utils::testValidInstance($newProvider, WritableWorldProvider::class);
 		$this->newProvider = $newProvider;
 		$this->logger = new \PrefixedLogger($logger, "World Converter: " . $this->oldProvider->getWorldData()->getName());
 		$this->chunksPerProgressUpdate = $chunksPerProgressUpdate;
@@ -105,10 +99,7 @@ class FormatConverter{
 		}
 
 		$this->logger->info("Conversion completed");
-		/**
-		 * @see WritableWorldProvider::__construct()
-		 */
-		return new $this->newProvider($path);
+		return $this->newProvider->fromPath($path);
 	}
 
 	private function generateNew() : WritableWorldProvider{
@@ -120,7 +111,7 @@ class FormatConverter{
 			$this->logger->info("Found previous conversion attempt, deleting...");
 			Filesystem::recursiveUnlink($convertedOutput);
 		}
-		$this->newProvider::generate($convertedOutput, $data->getName(), WorldCreationOptions::create()
+		$this->newProvider->generate($convertedOutput, $data->getName(), WorldCreationOptions::create()
 			->setGeneratorClass(GeneratorManager::getInstance()->getGenerator($data->getGenerator()))
 			->setGeneratorOptions($data->getGeneratorOptions())
 			->setSeed($data->getSeed())
@@ -128,10 +119,7 @@ class FormatConverter{
 			->setDifficulty($data->getDifficulty())
 		);
 
-		/**
-		 * @see WritableWorldProvider::__construct()
-		 */
-		return new $this->newProvider($convertedOutput);
+		return $this->newProvider->fromPath($convertedOutput);
 	}
 
 	private function populateLevelData(WorldData $data) : void{

src/world/format/io/ReadOnlyWorldProviderManagerEntry.php

@@ -23,6 +23,19 @@ declare(strict_types=1);
 
 namespace pocketmine\world\format\io;
 
-abstract class AbstractWorldProvider implements WorldProvider{
+/**
+ * @phpstan-type FromPath \Closure(string $path) : WorldProvider
+ */
+class ReadOnlyWorldProviderManagerEntry extends WorldProviderManagerEntry{
 
+	/** @phpstan-var FromPath */
+	private \Closure $fromPath;
+
+	/** @phpstan-param FromPath $fromPath */
+	public function __construct(\Closure $isValid, \Closure $fromPath){
+		parent::__construct($isValid);
+		$this->fromPath = $fromPath;
+	}
+
+	public function fromPath(string $path) : WorldProvider{ return ($this->fromPath)($path); }
 }

src/world/format/io/WorldProvider.php

@@ -25,17 +25,8 @@ namespace pocketmine\world\format\io;
 
 use pocketmine\world\format\Chunk;
 use pocketmine\world\format\io\exception\CorruptedChunkException;
-use pocketmine\world\format\io\exception\CorruptedWorldException;
-use pocketmine\world\format\io\exception\UnsupportedWorldFormatException;
 
 interface WorldProvider{
-
-	/**
-	 * @throws CorruptedWorldException
-	 * @throws UnsupportedWorldFormatException
-	 */
-	public function __construct(string $path);
-
 	/**
 	 * Returns the lowest buildable Y coordinate of this world
 	 */
@@ -48,12 +39,6 @@ interface WorldProvider{
 
 	public function getPath() : string;
 
-	/**
-	 * Tells if the path is a valid world.
-	 * This must tell if the current format supports opening the files in the directory
-	 */
-	public static function isValid(string $path) : bool;
-
 	/**
 	 * Loads a chunk (usually from disk storage) and returns it. If the chunk does not exist, null is returned.
 	 *

src/world/format/io/WorldProviderManager.php

@@ -23,7 +23,6 @@ declare(strict_types=1);
 
 namespace pocketmine\world\format\io;
 
-use pocketmine\utils\Utils;
 use pocketmine\world\format\io\leveldb\LevelDB;
 use pocketmine\world\format\io\region\Anvil;
 use pocketmine\world\format\io\region\McRegion;
@@ -33,80 +32,62 @@ use function trim;
 
 final class WorldProviderManager{
 	/**
-	 * @var string[]
-	 * @phpstan-var array<string, class-string<WorldProvider>>
+	 * @var WorldProviderManagerEntry[]
+	 * @phpstan-var array<string, WorldProviderManagerEntry>
 	 */
 	protected $providers = [];
 
-	/**
-	 * @var string
-	 * @phpstan-var class-string<WritableWorldProvider>
-	 */
-	private $default = LevelDB::class;
+	private WritableWorldProviderManagerEntry $default;
 
 	public function __construct(){
-		$this->addProvider(Anvil::class, "anvil");
-		$this->addProvider(McRegion::class, "mcregion");
-		$this->addProvider(PMAnvil::class, "pmanvil");
-		$this->addProvider(LevelDB::class, "leveldb");
+		$leveldb = new WritableWorldProviderManagerEntry(\Closure::fromCallable([LevelDB::class, 'isValid']), fn(string $path) => new LevelDB($path), \Closure::fromCallable([LevelDB::class, 'generate']));
+		$this->default = $leveldb;
+		$this->addProvider($leveldb, "leveldb");
+
+		$this->addProvider(new ReadOnlyWorldProviderManagerEntry(\Closure::fromCallable([Anvil::class, 'isValid']), fn(string $path) => new Anvil($path)), "anvil");
+		$this->addProvider(new ReadOnlyWorldProviderManagerEntry(\Closure::fromCallable([McRegion::class, 'isValid']), fn(string $path) => new McRegion($path)), "mcregion");
+		$this->addProvider(new ReadOnlyWorldProviderManagerEntry(\Closure::fromCallable([PMAnvil::class, 'isValid']), fn(string $path) => new PMAnvil($path)), "pmanvil");
 	}
 
 	/**
 	 * Returns the default format used to generate new worlds.
-	 *
-	 * @phpstan-return class-string<WritableWorldProvider>
 	 */
-	public function getDefault() : string{
+	public function getDefault() : WritableWorldProviderManagerEntry{
 		return $this->default;
 	}
 
-	/**
-	 * Sets the default format.
-	 *
-	 * @param string $class Class implementing WritableWorldProvider
-	 * @phpstan-param class-string<WritableWorldProvider> $class
-	 *
-	 * @throws \InvalidArgumentException
-	 */
-	public function setDefault(string $class) : void{
-		Utils::testValidInstance($class, WritableWorldProvider::class);
-
+	public function setDefault(WritableWorldProviderManagerEntry $class) : void{
 		$this->default = $class;
 	}
 
-	/**
-	 * @phpstan-param class-string<WorldProvider> $class
-	 */
-	public function addProvider(string $class, string $name, bool $overwrite = false) : void{
-		Utils::testValidInstance($class, WorldProvider::class);
-
+	public function addProvider(WorldProviderManagerEntry $providerEntry, string $name, bool $overwrite = false) : void{
 		$name = strtolower($name);
 		if(!$overwrite and isset($this->providers[$name])){
 			throw new \InvalidArgumentException("Alias \"$name\" is already assigned");
 		}
 
-		$this->providers[$name] = $class;
+		$this->providers[$name] = $providerEntry;
 	}
 
 	/**
 	 * Returns a WorldProvider class for this path, or null
 	 *
-	 * @return string[]
-	 * @phpstan-return array<string, class-string<WorldProvider>>
+	 * @return WorldProviderManagerEntry[]
+	 * @phpstan-return array<string, WorldProviderManagerEntry>
 	 */
 	public function getMatchingProviders(string $path) : array{
 		$result = [];
-		foreach($this->providers as $alias => $provider){
-			if($provider::isValid($path)){
-				$result[$alias] = $provider;
+		foreach($this->providers as $alias => $providerEntry){
+			if($providerEntry->isValid($path)){
+				$result[$alias] = $providerEntry;
 			}
 		}
 		return $result;
 	}
 
 	/**
-	 * @return string[]
-	 * @phpstan-return array<string, class-string<WorldProvider>>
+	 * @return WorldProviderManagerEntry[]
+	 * @phpstan-return array<string, WorldProviderManagerEntry>
 	 */
 	public function getAvailableProviders() : array{
 		return $this->providers;
@@ -114,10 +95,8 @@ final class WorldProviderManager{
 
 	/**
 	 * Returns a WorldProvider by name, or null if not found
-	 *
-	 * @phpstan-return class-string<WorldProvider>|null
 	 */
-	public function getProviderByName(string $name) : ?string{
+	public function getProviderByName(string $name) : ?WorldProviderManagerEntry{
 		return $this->providers[trim(strtolower($name))] ?? null;
 	}
 }

src/world/format/io/WorldProviderManagerEntry.php

@@ -0,0 +1,53 @@
+<?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\world\format\io;
+
+use pocketmine\world\format\io\exception\CorruptedWorldException;
+use pocketmine\world\format\io\exception\UnsupportedWorldFormatException;
+
+/**
+ * @phpstan-type IsValid \Closure(string $path) : bool
+ */
+abstract class WorldProviderManagerEntry{
+
+	/** @phpstan-var IsValid */
+	protected \Closure $isValid;
+
+	/** @phpstan-param IsValid $isValid */
+	protected function __construct(\Closure $isValid){
+		$this->isValid = $isValid;
+	}
+
+	/**
+	 * Tells if the path is a valid world.
+	 * This must tell if the current format supports opening the files in the directory
+	 */
+	public function isValid(string $path) : bool{ return ($this->isValid)($path); }
+
+	/**
+	 * @throws CorruptedWorldException
+	 * @throws UnsupportedWorldFormatException
+	 */
+	abstract public function fromPath(string $path) : WorldProvider;
+}

src/world/format/io/WritableWorldProvider.php

@@ -24,14 +24,8 @@ declare(strict_types=1);
 namespace pocketmine\world\format\io;
 
 use pocketmine\world\format\Chunk;
-use pocketmine\world\WorldCreationOptions;
 
 interface WritableWorldProvider extends WorldProvider{
-	/**
-	 * Generate the needed files in the path given
-	 */
-	public static function generate(string $path, string $name, WorldCreationOptions $options) : void;
-
 	/**
 	 * Saves a chunk (usually to disk).
 	 */

src/world/format/io/WritableWorldProviderManagerEntry.php

@@ -0,0 +1,58 @@
+<?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\world\format\io;
+
+use pocketmine\world\WorldCreationOptions;
+
+/**
+ * @phpstan-type FromPath \Closure(string $path) : WritableWorldProvider
+ * @phpstan-type Generate \Closure(string $path, string $name, WorldCreationOptions $options) : void
+ */
+final class WritableWorldProviderManagerEntry extends WorldProviderManagerEntry{
+	/** @phpstan-var FromPath */
+	private \Closure $fromPath;
+	/** @phpstan-var Generate */
+	private \Closure $generate;
+
+	/**
+	 * @phpstan-param FromPath $fromPath
+	 * @phpstan-param Generate $generate
+	 */
+	public function __construct(\Closure $isValid, \Closure $fromPath, \Closure $generate){
+		parent::__construct($isValid);
+		$this->fromPath = $fromPath;
+		$this->generate = $generate;
+	}
+
+	public function fromPath(string $path) : WritableWorldProvider{
+		return ($this->fromPath)($path);
+	}
+
+	/**
+	 * Generates world manifest files and any other things needed to initialize a new world on disk
+	 */
+	public function generate(string $path, string $name, WorldCreationOptions $options) : void{
+		($this->generate)($path, $name, $options);
+	}
+}

tests/phpunit/world/format/io/InterfaceWorldProvider.php

@@ -1,28 +0,0 @@
-<?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\world\format\io;
-
-interface InterfaceWorldProvider extends WorldProvider{
-
-}

tests/phpunit/world/format/io/LevelProviderManagerTest.php

@@ -1,60 +0,0 @@
-<?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\world\format\io;
-
-use PHPUnit\Framework\TestCase;
-
-class LevelProviderManagerTest extends TestCase{
-
-	/** @var WorldProviderManager */
-	private $providerManager;
-
-	protected function setUp() : void{
-		$this->providerManager = new WorldProviderManager();
-	}
-
-	public function testAddNonClassProvider() : void{
-		$this->expectException(\InvalidArgumentException::class);
-
-		$this->providerManager->addProvider("lol", "nope");
-	}
-
-	public function testAddAbstractClassProvider() : void{
-		$this->expectException(\InvalidArgumentException::class);
-
-		$this->providerManager->addProvider(AbstractWorldProvider::class, "abstract");
-	}
-
-	public function testAddInterfaceProvider() : void{
-		$this->expectException(\InvalidArgumentException::class);
-
-		$this->providerManager->addProvider(InterfaceWorldProvider::class, "interface");
-	}
-
-	public function testAddWrongClassProvider() : void{
-		$this->expectException(\InvalidArgumentException::class);
-
-		$this->providerManager->addProvider(LevelProviderManagerTest::class, "bad_class");
-	}
-}