kryo_fun.scala

import java.io._
import com.esotericsoftware.kryo.Kryo
import com.esotericsoftware.kryo.io._

sealed trait Gen[T] {
  def reader: GenReader[T]
}
sealed trait GenReader[T] {
  def toGen: T
}

case class Foo(n: Int, s: String) extends Gen[Foo] {
  def reader: FooReader = {
    val f = new FooReader()
    f.n = n
    f.s = s
    f
  }
}

case class Bar(x: Double) extends Gen[Bar] {
  def reader: BarReader = {
    val f = new BarReader()
    f.x = x
    f
  }
}

class FooReader() extends GenReader[Foo] {
  var n: Int = 0;
  var s: String = ""
  def toGen = Foo(n, s)
}

class BarReader() extends GenReader[Bar] {
  var x: Double = 0.0
  def toGen = Bar(x)
}

val foos = Array(
  Foo(1, "one"),
  Foo(2, "two"),
  Foo(3, "three"),
  Foo(100, "One Hundred"),
  Foo(1984, "One thousand nine hundred eighty four"),
  Foo(6,"six")
)

val kryo = new Kryo()
kryo.register(classOf[FooReader])

val output = new Output( new FileOutputStream("foo_list.bin"))
kryo.writeObject(output, foos.map(_.reader))
output.close()

/*

> hexdump -C foo_list.bin
00000000  01 07 0c 01 02 01 6f 6e  e5 0c 01 04 01 74 77 ef  |......on.....tw.|
00000010  0c 01 06 01 74 68 72 65  e5 0c 01 c8 01 01 4f 6e  |....thre......On|
00000020  65 20 48 75 6e 64 72 65  e4 0c 01 80 1f 01 4f 6e  |e Hundre......On|
00000030  65 20 74 68 6f 75 73 61  6e 64 20 6e 69 6e 65 20  |e thousand nine |
00000040  68 75 6e 64 72 65 64 20  65 69 67 68 74 79 20 66  |hundred eighty f|
00000050  6f 75 f2 0c 01 0c 01 73  69 f8                    |ou.....si.|

*/

val input = new Input(new FileInputStream("foo_list.bin"))
val qq = kryo.readObject(input, classOf[Array[FooReader]]).map(_.toGen)
input.close()