cljs.reader/read-token

(defn read-token
  [rdr initch]
  (loop [sb (StringBuffer. initch)
         ch (read-char rdr)]
    (if (or (nil? ch)
            (whitespace? ch)
            (macro-terminating? ch))
      (do (unread rdr ch) (.toString sb))
      (recur (do (.append sb ch) sb) (read-char rdr)))))