Wordpress get all post's editors.

wordpress

function getPostAuthors() {
    global $wpdb;
    $authors = array();
    $results = $wpdb->get_results( $wpdb->prepare("SELECT post_author FROM $wpdb->posts WHERE (post_type = '%s' AND ID = %d) OR (post_type = 'revision' AND post_parent = %d) GROUP BY post_author", get_post_type( get_the_ID() ), get_the_ID(), get_the_ID() ) );
    foreach ($results as $row) {
        if (isset($coma)) { 
            echo $coma;
        } else {
            $coma = ', ';
        }
      echo '<a href="mailto:' . get_the_author_meta('user_email', $row->post_author) . '"> ' . get_the_author_meta('display_name', $row->post_author) . '</a>';
    }
}