(?s)
(?:
  (<\w+
    (?:\s*\b\w+=
      (?:
        "[^<"]*"
        |
        '[^<']*'
      )
    )*
    \s*/?>
  )
  |
  (<!--.*?-->)
  |
  (<!\[CDATA\[.*?\]\]>)
  |
  (<!\w+.*?>)
  |
  (<\?xml.*?\?>)
  |
  (</\w+>)
)