T5 Strip double spaces in posts

t5-strip-double-spaces.php

<?php
/**
 * Plugin Name: T5 Strip double spaces in posts
 * Description: Replaces [space + no-break-space] with a regular space.
 * Plugin URI:  http://wordpress.stackexchange.com/questions/75197/remove-double-space-after-a-period
 * Version:     2012.12.06
 * Author:      Thomas Scholz
 * Author URI:  http://toscho.de
 * Licence:     MIT
 * License URI: http://opensource.org/licenses/MIT
 */

add_filter( 'wp_insert_post_data', 't5_strip_double_spaces', 20 );

/**
 * Filter post content.
 *
 * @wp-hook wp_insert_post_data
 * @param   array $data
 * @return  array
 */
function t5_strip_double_spaces( $data )
{
	// see http://www.fileformat.info/info/unicode/char/a0/index.htm
	$pattern = "~ \x{C2}\x{A0}~m";
	$data['post_content'] = preg_replace( $pattern, ' ', $data['post_content'] );
	return $data;
}