Add twig extension to handle instanceof from inside twig.

src/App.php

@@ -173,6 +173,9 @@ class App
             // Add Twig extension to integrate Kint
             $twig->addExtension(new \Kint\Twig\TwigExtension());
 
+            // Add Twig extension to check if something is an instance of a known class or entity
+            $twig->addExtension(new Extensions\InstanceOfExtension());
+
             // Add Twig Translate from symfony/twig-bridge
             $selectedLanguage = $sessionService->has('Language') ? $sessionService->get('Language') : 'en_US';
             $twig->addExtension(new SymfonyTwigExtensions\TranslationExtension($translator));

src/Twig/Extensions/InstanceOfExtension.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace Benzine\Twig\Extensions;
+
+use Twig\Extension\AbstractExtension;
+use Twig\TwigTest;
+
+class InstanceOfExtension extends AbstractExtension
+{
+    public function getTests()
+    {
+        return [
+            new TwigTest('instanceof', [$this, 'isInstanceOf']),
+        ];
+    }
+
+    public function isInstanceOf($var, $instance)
+    {
+        if (is_object($var) && $var instanceof $instance) {
+            return true;
+        }
+
+        return false;
+    }
+
+    public function getName()
+    {
+        return 'instanceof_extension';
+    }
+}