Convert StudlyCase and snake_case substrings to "spaced words" while preserving acronyms within twig expressions

Symfony twig

How to add space following capital letters only when it is following small letters.

{{ 'IWantHTML'|humanize }} //displays 'I want h t m l'. // it should be 'I want HTML'.

The other thing is it makes everything small letters following the first letter. e.x.

{{ 'IWantHTML'|humanize }} // should be 'I Want HTML'.
{{ 'i_want_html'|humanize}} // should be 'I want html'.
{{ 'CustomerPickSale2'|humanize}} // should be 'Customer Pick Sale2'.

Below custom twig filter works!!

new Twig_SimpleFilter('readable', array($this, 'readableFormat'))

 /**
 * @param $string
 * @return mixed
 */
public function readableFormat($string)
{
    $match_filter = array(
        '/(?<!\ )[A-Z][a-z]+/',
        '/(?<!\ )[A-Z][A-Z]+/',
    );

    $Words = preg_replace($match_filter, ' $0', trim($string));
    return str_replace('_', ' ', $Words);
}

{{ 'IWantHTML'|readable }} // I Want HTML
{{ 'i_want_html'|readable|ucfirst }} // I want html
{{ 'CustomerPickSale2'|readable|ucfirst }} // Customer Pick Sale2