不断出现语法错误，不确定原因。这是我正在使用的代码

function my_epl_listing_default_sort($query) {
    // Do nothing if in dashboard or not an archive page
    if ( is_admin() || ! $query->is_main_query() )
        return;

    // Do nothing if Easy Property Listings is not active
    if ( ! function_exists( \'epl_all_post_types\' ) )
        return;

    // Do nothing if doing search
    if ( epl_is_search() )
        return;

    /// Sort EPL listings by price on archive page
    if ( is_post_type_archive( epl_all_post_types() == \'true\' ) ) {
        $query->set( \'meta_key\', \'title\' );
        $query->set( \'order\',    \'ASC\' );
        $query->set( \'orderby\',  \'meta_value\'  );
        return;
    }
}
add_action( \'pre_get_posts\', \'my_epl_listing_default_sort\' );