Plugin Fix Empty Titles

fix-empty-titles.php

<?php # -*- coding: utf-8 -*-
/*
Plugin Name: Fix Empty Titles
Description: Replaces missing titles with the first characters from post body.
Version:     1.1
Required:    3.2
Author:      Thomas Scholz
Author URI:  http://toscho.de
License:     GPL

Based on an idea of Konstantin Kovshenin. See
http://kovshenin.com/2011/10/wordpress-posts-without-titles-in-rss-feeds-3621/
*/
/**
 * , Copyright (C) 2011 Thomas Scholz
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

! defined( 'ABSPATH' ) and exit;

add_action( 'save_post', 't5_fix_empty_title', 11, 2 );

/**
 * Fills an empty post title from the first words of the post.
 *
 * @param  int    $post_id      Post ID
 * @param  object $post         Post object
 * @return void
 */
function t5_fix_empty_title( $post_id, $post )
{
	if ( ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE )
		or ! current_user_can( 'edit_post', $post_id )
		or ! empty ( $post->post_title )
		or empty ( $post->post_content )
		or wp_is_post_revision( $post )
	)
	{ // Noting to do.
		return;
	}

	// Remove all tags and replace breaks whith white space.
	$no_tags = wp_strip_all_tags( $post->post_content, TRUE );

	// The post content contains just markup.
	if ( '' === $no_tags )
	{
		return;
	}

	$length = apply_filters( 't5_fix_empty_title_length', 20 );
	$words  = preg_split( "/\s+/", $no_tags, $length, PREG_SPLIT_NO_EMPTY );
	array_pop( $words );

	$title = implode( ' ', $words );
	// Add a no break space and an ellipsis at the end.
	$title = rtrim( $title, '.,!?…*' ) . ' …';

	wp_update_post( array ( 'ID' => $post_id, 'post_title' => $title ) );
}

Absolutely great!
I wonder however, it it's possible to do this but instead of just the $length of some words, it could find the first dot, ellipsis, exclamation mark or question mark?