test.clj

(defn re-seq-with-pos
  [re str]
  (let [*matcher* (re-matcher re str)]
    (loop [match (re-find *matcher*)
           matches []]
      (if match
        (let [start (.start *matcher*)]
          (recur (re-find *matcher*)
                 (conj matches {:start start :end (+ start (count (first match))) :match match})))
        matches))))


(re-seq-with-pos #"(?ms)\{\{(.*?)\}\}" "Test {{wat}} hello {{wut}}")
;; [{:start 5, :end 12, :match ["{{wat}}" "wat"]} {:start 19, :end 26, :match ["{{wut}}" "wut"]}]

(defn highlight-code
  [html]
  (loop [curr 0
         matches (->> (re-seq-with-pos #"(?ms)\<code(.*?)\>(.*?)\<\/code\>" html)
                        (pmap #(assoc % :highlighted
                                      (perform-highlight
                                       (get-language-from-code-tag-attrs (nth (:match %) 1))
                                       (nth (:match %) 2)))))
         res []]
    (if (empty? matches)
      (clojure.string/join (conj res (subs html curr)))
      (let [match (first matches)]
        (recur (:end match) (rest matches) (-> res (conj (subs html curr (:start match))) (conj (:highlighted match))))))) )