Convert anything to HTML entities (including unicodes.)

gistfile1.php

<?php

function everythingEntities($str, $pattern = '/./u')
{
    return preg_replace_callback($pattern, function ($match) {
        list(, $ord) = unpack('N', mb_convert_encoding($match[0], 'UCS-4BE', 'UTF-8'));
        return sprintf('&#%s;', $ord);
    }, $str);
}