Add daverandom/callback-validator as a dependency

composer.json

@@ -29,7 +29,8 @@
       "pocketmine/binaryutils": "^0.1.0",
       "pocketmine/nbt": "^0.2.1",
       "pocketmine/math": "^0.2.0",
-      "pocketmine/snooze": "^0.1.0"
+      "pocketmine/snooze": "^0.1.0",
+      "daverandom/callback-validator": "dev-master"
    },
    "autoload": {
       "psr-4": {

composer.lock

@@ -4,8 +4,48 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "3536995c56bfc3dbd6ccc0994e88a636",
+    "content-hash": "2d120a3dd7d68958809c3662d1cb7c99",
     "packages": [
+        {
+            "name": "daverandom/callback-validator",
+            "version": "dev-master",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/DaveRandom/CallbackValidator.git",
+                "reference": "d87a08cddbc6099816ed01e50ce25cdfc43b542f"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/DaveRandom/CallbackValidator/zipball/d87a08cddbc6099816ed01e50ce25cdfc43b542f",
+                "reference": "d87a08cddbc6099816ed01e50ce25cdfc43b542f",
+                "shasum": ""
+            },
+            "require": {
+                "ext-reflection": "*",
+                "php": ">=7.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^6.0"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "DaveRandom\\CallbackValidator\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Chris Wright",
+                    "email": "cw@daverandom.com"
+                }
+            ],
+            "description": "Tools for validating callback signatures",
+            "time": "2017-04-03T15:22:41+00:00"
+        },
         {
             "name": "pocketmine/binaryutils",
             "version": "0.1.1",
@@ -227,7 +267,8 @@
     "aliases": [],
     "minimum-stability": "stable",
     "stability-flags": {
-        "ext-pthreads": 20
+        "ext-pthreads": 20,
+        "daverandom/callback-validator": 20
     },
     "prefer-stable": false,
     "prefer-lowest": false,

src/pocketmine/utils/Utils.php

@@ -27,6 +27,7 @@ declare(strict_types=1);
 
 namespace pocketmine\utils;
 
+use DaveRandom\CallbackValidator\CallbackType;
 use pocketmine\ThreadManager;
 
 /**
@@ -593,4 +594,41 @@ class Utils{
 
 		return true; //stfu operator
 	}
+
+	public static function testValidInstance(string $className, string $baseName) : void{
+		try{
+			$base = new \ReflectionClass($baseName);
+		}catch(\ReflectionException $e){
+			throw new \InvalidArgumentException("Base class $baseName does not exist");
+		}
+
+		try{
+			$class = new \ReflectionClass($className);
+		}catch(\ReflectionException $e){
+			throw new \InvalidArgumentException("Class $className does not exist");
+		}
+
+		if(!$class->isSubclassOf($baseName)){
+			throw new \InvalidArgumentException("Class $className does not " . ($base->isInterface() ? "implement" : "extend") . " " . $baseName);
+		}
+		if(!$class->isInstantiable()){
+			throw new \InvalidArgumentException("Class $className cannot be constructed");
+		}
+	}
+
+	/**
+	 * Verifies that the given callable is compatible with the desired signature. Throws a TypeError if they are
+	 * incompatible.
+	 *
+	 * @param callable $signature Dummy callable with the required parameters and return type
+	 * @param callable $subject Callable to check the signature of
+	 *
+	 * @throws \DaveRandom\CallbackValidator\InvalidCallbackException
+	 * @throws \TypeError
+	 */
+	public static function validateCallableSignature(callable $signature, callable $subject) : void{
+		if(!($sigType = CallbackType::createFromCallable($signature))->isSatisfiedBy($subject)){
+			throw new \TypeError("Declaration of callable `" . CallbackType::createFromCallable($subject) . "` must be compatible with `" . $sigType . "`");
+		}
+	}
 }