Regular Expression Matches

(defun regex-matches (re s &optional start)
  "Given a regular expression and a string, return a sequence of
matches, including groups, if any."
  (cl-labels
      ((regex-matches
        (acc index)
        (let ((this-match (match-string index s)))
          (cond
           (this-match (regex-matches (cons this-match acc) (1+ index)))
           (t (reverse acc))))))

    (when (string-match re s start)
      (regex-matches '() 0))))