lib/Twig/lib/Twig/FileExtensionEscapingStrategy.php
public static function guess($name)
    {
        if (in_array(substr($name, -1), array('/', '\\'))) {
            return 'html'; // return html for directories
        }

        if ('.twig' === substr($name, -5)) {
            $name = substr($name, 0, -5);
        }

        $extension = pathinfo($name, PATHINFO_EXTENSION);

        switch ($extension) {
            case 'js':
                return 'js';

            case 'css':
                return 'css';

            case 'txt':
                return false;

            default:
                return 'html';
        }
    }
public static function guess($name)
    {
        if (in_array(substr($name, -1), array('/', '\\'))) {
            return 'html'; // return html for directories
        }

        if ('.twig' === substr($name, -5)) {
            $name = substr($name, 0, -5);
        }

        $extension = pathinfo($name, PATHINFO_EXTENSION);

        switch ($extension) {
            case 'js':
                return 'js';

            case 'css':
                return 'css';

            case 'txt':
                return false;

            default:
                return 'html';
        }
    }
Guesses the best autoescaping strategy based on the file name.

@param string $name The template name

@return string|false The escaping strategy name to use or false to disable