TwigPHPExtension.php

<?php
class TwigPHPExtension extends \Twig_Extension {

    public function getName()
    {
        return 'php_twig_extension';
    }

    public function getFunctions()
    {
        return array(
            new \Twig_SimpleFunction('php_*', array($this,'phpFunctions'),array('is_safe' => array('html')))
        );
    }

    public function phpFunctions()
    {
        $arg_list = func_get_args();
        $function = array_shift($arg_list);

        if(is_callable($function)){
            return call_user_func_array($function, $arg_list);
        }

        $errMsg = 'Called to an undefined function : <b>php_' . $function . "</b> ";

        trigger_error($errMsg, E_USER_NOTICE);

        return NULL;
    }
}