Add the evaluate Twig function

system/src/Grav/Common/Twig/TwigExtension.php

@@ -89,6 +89,7 @@ class TwigExtension extends \Twig_Extension
             new \Twig_simpleFunction('t', [$this, 'translate']),
             new \Twig_simpleFunction('ta', [$this, 'translateArray']),
             new \Twig_SimpleFunction('url', [$this, 'urlFunc']),
+            new \Twig_SimpleFunction('evaluate', [$this, 'evaluateFunc']),
         ];
     }
 
@@ -450,6 +451,19 @@ class TwigExtension extends \Twig_Extension
         return $resource ? rtrim($uri->rootUrl($domain), '/') . '/' . $resource : null;
     }
 
+    /**
+     * Evaluate a string
+     *
+     * @example {{ evaluate('grav.language.getLanguage') }}
+     *
+     * @param  string $input    String to be evaluated
+     * @return string           Returns the evaluated string
+     */
+    public function evaluateFunc($input)
+    {
+        return $this->grav['twig']->processString("{{ $input }}");
+    }
+
     /**
      * Based on Twig_Extension_Debug / twig_var_dump
      * (c) 2011 Fabien Potencier