(ns org.clojars.making.cloudure.conv
  (:import (org.apache.hadoop.io IntWritable LongWritable DoubleWritable Text))
  )

(defmulti conv class)

(defmethod conv :default [x]
  x)

(defmacro defconv [conv-map]
  `(do
     ~@(for [c conv-map]
         `(defmethod conv ~(first c) [x#]
            (new ~(second c) x#)))))

(defn conv-write [key value context]
  (.write context (conv key) (conv value)))


(defconv {Integer IntWritable,
          Double DoubleWritable,
          Long LongWritable,
          String Text
          ;; and more
          })

(comment
  (do
    (defmethod
      conv
      Integer
      [x__4915__auto__]
      (new IntWritable x__4915__auto__))
    (defmethod
      conv
      Double
      [x__4915__auto__]
      (new DoubleWritable x__4915__auto__))
    (defmethod
      conv
      Long
      [x__4915__auto__]
      (new LongWritable x__4915__auto__))
    (defmethod conv String [x__4915__auto__] (new Text x__4915__auto__)))
  )