neg-lookup-in-action.clj

;; implicit pass on :space
(def g 
  (grammar {:space :space
            :main :expr*}
    :space [" "+]
    :expr #{:symbol ["(" :expr* ")"]}
    :symbol ["a"+ "b" (but "a" "b")]))

(comment
=> (-> g (step "(ab ab)") eof) ; yuk!
([nil [[{:tag :expr, :content ["(" {:tag :expr, :content [{:tag :symbol, :content ["ab"], :length 2}], :length 2} {:tag :space, :content [" "], :length 1} {:tag :expr, :content [{:tag :symbol, :content ["ab"], :length 2}], :length 2} ")"], :length 7}] []] nil])
)