css selector in laser

laser_css.clj

(let [re-1 #"([^#\.:]*)((?:[#\.][^#\.:]+)*)"
      re-2 #"([#\.])([^#\.:]+)"]
  (defn css
    "Laser selector for css stuff. Just handles the AND format
     of foo#bar.baz.bang, no ORing."
    [s]
    (let [[_ a b] (re-matches re-1 (name s))]
      (assert (or (seq a) (seq b)) "Bad css selector.")
      (apply l/and
             (if (empty? a)
               (constantly true)
               (l/element= a))
             (if (empty? b)
               []
               (for [[_ type name] (re-seq re-2 b)]
                 ((case type "#" l/id= "." l/class=)
                  name)))))))