post_install() {
  echo ":: Installing SAX XML Parsers"
  /usr/bin/perl -MXML::SAX -e "XML::SAX->add_parser(q(XML::LibXML::SAX::Parser))->save_parsers()"
  /usr/bin/perl -MXML::SAX -e "XML::SAX->add_parser(q(XML::LibXML::SAX))->save_parsers()"
}

post_upgrade() {
  if [[ -e /usr/share/perl5/vendor_perl/XML/SAX/ParserDetails.ini ]] \
    || (( $(grep -c XML::LibXML::SAX /usr/share/perl5/vendor_perl/XML/SAX/ParserDetails.ini) == 0 ))
  then
      post_install
  fi
}