<?php

require_once(__DIR__ . '/../Twig-1.15.1/lib/Twig/Autoloader.php');
Twig_Autoloader::register();

$loader = new Twig_Loader_String();
$twig = new Twig_Environment($loader);

$filter = new Twig_SimpleFilter('test', function($input, $unsafe_arg)
{
   return '<div>' . $input . ' -- ' . $unsafe_arg . '</div>';
}, array ('pre_escape' => 'html', 'is_safe' => array ('html')));

$twig->addFilter($filter);

echo $twig->render("{{ var|test(var2) }}\n", array('var' => '<p>foo</p>', 'var2' => '<p>bar</p>'));

// result:
// <div>&lt;p&gt;foo&lt;/p&gt; -- <p>bar</p></div>