- $html = preg_replace(
- ["/\r?\n/", "'(?:<br />\n?){2}'"],
- ["<br />\n", "</p>\n\n<p>"],
- htmlspecialchars($input)
- );
+ $markup = [
+ "/\r\n?/" => "\n", # unix newlines
+ "/ +\n/" => "<br />", # trailing spaces for hard line break
+ "/\n/" => "</p>\n<p>", # newlines start paragraphs
+ '/\b_(\w+)_\b/' => '<em>$1</em>', # italic
+ '/\b\*(\w+)\*\b/' => '<strong>$1</strong>', # bold
+ ];
+ $html = preg_replace(array_keys($markup), array_values($markup), htmlspecialchars($input));