markdown.cljs

(defn simple-md-parser
  "Simple markdown parser."
  [s special]
  (let [it (iter s)
        out-state (fn [out text state]
                    (conj out {:text text
                               :state (into [] (keep (fn [[k v]]
                                                       (when v k))) state)}))]
    (loop [out []
           state {}
           text ""]
      (if ^boolean (.hasNext it)
        (let [ch (.next it)]
          (if (contains? special ch)
            (recur (if (not (empty? text)) (out-state out text state) out)
                   (update state ch not) "")
            (recur out state (str text ch))))
        (if (not (empty? text))
          (out-state out text state)
          out)))))

xexample.clj

(simple-md-parser "A *bold_bold+under*_ _underline /italics+underline"
                    #{"*" "_" "/"})

[{:text "A ", :state []}
 {:text "bold", :state ["*"]}
 {:text "bold+under", :state ["*" "_"]}
 {:text " ", :state []}
 {:text "underline ", :state ["_"]}
 {:text "italics+underline", :state ["_" "/"]}]