Generator みたいななにか

generator.scala

package net.shomah4a.utils.generator

import scala.util.continuations.{reset, shift, cpsParam}


object Generator
{
  type GenParam[T] = (Option[T], Option[GeneratorSupport[T]])

  def gen[T](f: () => Unit@cpsParam[GenParam[T], GenParam[T]]) = new Generator[T](f)
  

  def yld[T](v: T) =
    {
      shift[Unit, GenParam[T], GenParam[T]] {ctx: (Unit => GenParam[T]) =>
        {
          (Some(v), Some(new GeneratorSupport[T]({() => ctx()}))).asInstanceOf[GenParam[T]]
        }}
    }
}


class GeneratorSupport[T](f: (() => (Option[T], Option[GeneratorSupport[T]])))
{
  def apply() = f()
}


class Generator[T](f: () => Unit @cpsParam[Generator.GenParam[T], Generator.GenParam[T]]) extends Iterator[T]
{
  var x = reset {

    f()

    (None, None):Generator.GenParam[T]
  }:Generator.GenParam[T]


  var value: Option[T] = x._1
  var context: Option[GeneratorSupport[T]] = x._2


  def hasNext() =
    {
      context != None
    }


  def next() =
    {
      val prev = this.value

      val (v, ctx) = (this.context.get)()

      this.value = v
      this.context = ctx

      prev.get
    }
}