(trans-meisuu "千二百億十三")

meisuu.clj

(use 'clojure.contrib.str-utils)

(def digits {"零" 0 "一" 1 "二" 2 "三" 3 "四" 4 "五" 5 "六" 6 "七" 7 "八" 8 "九" 9})

(defn- str-first [s]
  (str (.charAt s 0)))

(defn- trans-ichi [s]
  (let [n (re-find #"[一二三四五六七八九]$" s)]
    (if (nil? n) 0 (digits n))))

(defn- trans-jyuu [s]
  (try
    (let [n (str-first (first (re-find #"([二三四五六七八九]十|十)" s)))]
      (if (nil? n) 0
	  (let [d (digits n)]
	    (if (nil? d) 10
		(* 10 d)))))
    (catch NullPointerException _ 0)))

(defn- trans-hyaku [s]
  (try
    (let [n (str-first (first (re-find #"([二三四五六七八九]百|百)" s)))]
      (if (nil? n) 0
	  (let [d (digits n)]
	    (if (nil? d) 100
		(* 100 d)))))
    (catch NullPointerException _ 0)))

(defn- trans-sen [s]
  (try
    (let [n (str-first (first (re-find #"([二三四五六七八九]千|千)" s)))]
      (if (nil? n) 0
	  (let [d (digits n)]
	    (if (nil? d) 1000
		(* 1000 d)))))
    (catch NullPointerException _ 0)))

(defn- trans-keta [s]
  (+ (trans-sen s) (trans-hyaku s) (trans-jyuu s) (trans-ichi s)))

(defn- split-keta [s]
  (re-partition #"[零一二三四五六七八九十百千]+" s))

(def meisuu    {"万"        4
		"億"        8   
		"兆"       12  
		"京"       16
		"垓"       20
		"叙"       24
		"穣"       28
		"溝"       32
		"澗"       36
		"正"       40
		"載"       44
		"極"       48
		"恒河沙"   52
		"阿僧祇"   56
		"那由多"   60
		"不可思議" 64
		"無量大数" 68})

(defn- trans-mei [s]
  (loop [m (meisuu s) res 1]
    (if (zero? m) res
	(recur (dec m) (* res 10)))))

(defn- trans-meisuu-sub [lst]
  (if (nil? lst) 0
      (if (= (count lst) 1) (trans-keta (first lst))
	  (+ (* (trans-keta (first lst)) (trans-mei (second lst)))
	     (trans-meisuu-sub (next (next lst)))))))

(defn trans-meisuu [s]
  (trans-meisuu-sub (next (split-keta s))))