parse-or-conds.clj

(use 'clojure.contrib.seq-utils)

(defn- in-range?
  [i pair]
  (and (>= i (first pair)) (<= i (last pair))))

(defn- glue-pairs
  [pairs]
  (let [idxs (flatten pairs)
	freqs (frequencies idxs)]
    (partition-all 2
		   (filter #(= 1 (freqs %)) idxs))))

(defn- or-clause-from-range
  [rng conditions]
  (flatten [:or (remove #(= :or %)
			(subvec conditions (first rng) (inc (last rng))))]))

(defn extract-or-clauses [conditions]
  (let [or-ed-ranges (glue-pairs (->> (indexed conditions)
				     (filter #(= :or (last %)))
				     (map first)
				     (map (fn [i] [(dec i) (inc i)]))))
	or-range-for-idx (fn [idx] (first
				    (filter
				     (partial in-range? idx) or-ed-ranges)))]
    (distinct
     (->> (indexed conditions)
	  (map #(let [or-range (or-range-for-idx (first %))]
		  (if or-range
		    (or-clause-from-range or-range conditions) (last %))))))))

;; user> (extract-or-clauses ["foo" "bar" :or "baz" :or "biz" "chunky bacon" "c" :or "l" :or "j"  "ohai"])
;; => ("foo" (:or "bar" "baz" "biz") "chunky bacon" (:or "c" "l" "j") "ohai")

(defn- in-range?
[i [lower upper]](= lower i upper))