This project can also be used in PHP 5.
(I suggest that its name should be changed.)
I found that it includes some deprecated function: ereg.
They introduced to replace with preg_match.
To fix, change line #177 of htmlparser.inc from
return ereg ("^[A-Za-z0-9_\-]+$", $name);
return preg_match ("/^[A-Za-z0-9_\-]+$/", $name);
the warning messages will be gone.