Clojureでテキスト入出力

Clojureでテキスト入出力を行う方法のメモ。

1 テキストファイル

;; 出力
(spit "test.txt" "Hello, World")

;; 入力
(assert (= "Hello, World" (slurp "test.txt")))

2 文字列

(with-open [in (java.io.StringReader. "Hello")]
  (assert (= \H (char (.read in))))
  'ok)

(with-open [in (clojure.java.io/reader (.getBytes "Hello"))]
  (assert (= "Hello" (.readLine in)))
  'ok)

(with-in-str "hoge"
  (assert (= "hoge" (read-line))))

3 XML

;; [org.clojure/data.xml "0.0.6"]
(require '[clojure.data.xml :as xml])
(xml/parse-str "<x id='1'><y>a</y><y id='2'>b</y></x>")

;; [enlive "1.0.0"]
(require '[net.cgrand.enlive-html :as enlive])
(let [s "<x id='1'><y>a</y><y id='2'>b</y></x>"
      x (with-in-str s (enlive/xml-resource *in*))]
  (assert (= '("b") (:content (first (enlive/select x [:#2]))))))

4 CSV

;; [org.clojure/data.csv "0.1.2"]
(require '[clojure.data.csv :as csv])

(let [s "a,\"b,c\",d\ne,fg,h\n"]
  (println (csv/read-csv s))
  (csv/write-csv *out* (csv/read-csv s))
  (assert (= s (with-out-str
                 (csv/write-csv *out* (csv/read-csv s)))))
  'ok)

5 JSON

;; [org.clojure/data.json "0.2.0"]
(require '[clojure.data.json :as json])
(let [m (json/read-str "{\"k1\": 1, \"k2\": \"val\"}")]
  (println m)
  (assert (= m (json/read-str (json/write-str m))))
  (with-open [out (clojure.java.io/writer "tmp.json")]
    (json/write m out))
  (with-open [in (clojure.java.io/reader "tmp.json")]
    (assert (= m (json/read in))))
  'ok)

;; オプションとして :key-fn や :value-fn を指定すると read/write 時にキーと値を変換できる
(println (= {:key 1.0}
            (json/read-str "{\"key\" : 1}"
                           :key-fn keyword
                           :value-fn #(double %2))))

6 INIファイル

;; [clojure-ini "0.0.1"]
(require '[clojure-ini.core :as ini])

(spit "test.ini" "[a]\nb=c\nd=e\n")
(assert (= {:a {:b "c", :d "e"}}
           (ini/read-ini "test.ini" :keywordize? true)))