root/lang/scala/sandbox/src/jp/ne/cappuccino/keisuken/scl/lang/Loop.scala @ 6683

package jp.ne.cappuccino.keisuken.scl.lang

object Loop {

  class BreakWithValue[T](var cond: Boolean, var value: Option[T]) {
    def this() = this(true, None)
    def apply(): Unit = {cond = false; value = None}
    def apply(v: T): Unit = {cond = false; value = Some(v)}
  }

  class Break(var cond: Boolean) {
    def this() = this(true)
    def apply(): Unit = cond = false
  }

  def forEach[A](iterable: Iterable[A])(p: (A, Break) => Unit): Unit = {
    val break = new Break()
    val iterator = iterable.elements
    while(break.cond && iterator.hasNext)
      p(iterator.next, break)
  }

  def findFor[A, B]
    (iterable: Iterable[A])(p: (A, BreakWithValue[B]) => Unit): Option[B] = {
    val break = new BreakWithValue[B]()
    val iterator = iterable.elements
    while(break.cond && iterator.hasNext)
      p(iterator.next, break)
    break.value
  }

  def whileLoop(cond: => Boolean)(p: Break => Unit): Unit = {
    val break = new Break()
    while(break.cond && cond) p(break)
  }

  def findWhile[A]
    (cond: => Boolean)(p: BreakWithValue[A] => Unit): Option[A] = {
    val break = new BreakWithValue[A]()
    while(break.cond && cond) p(break)
    break.value
  }

  def doWhile(cond: => Boolean)(p: Break => Unit): Unit = {
    val break = new Break()
    do p(break) while(break.cond && cond)
  }

  def findDoWhile[A]
    (cond: => Boolean)(p: BreakWithValue[A] => Unit): Option[A] = {
    val break = new BreakWithValue[A]()
    do p(break) while(break.cond && cond)
    break.value
  }

  def main(args: Array[String]) {

    forEach(1 to 10) {(i, break) =>
      if(i == 5) {
        println(i)
        break()
      }
    }

    var i = 0
    whileLoop(i < 10) {break =>
      if(i >= 5) {
        println(i)
        break()
      } else
        i += 1
    }

    i = 0
    doWhile({i += 1; i < 10}) {break =>
      if(i >= 5) {
        println(i)
        break()
      }
    }

    i = 0
    var result1 = findWhile[Int](true) {break =>
      if(i >= 5)
        break(i)
      else
        i += 1
    }
    result1 match {
      case Some(result) => println(result)
      case None => println("Not found")
    }

    i = 0
    val result2 = findWhile[Int](i < 10) {break =>
      if(i == 20)
        break(i)
      else
        i += 1
    }
    result2 match {
      case Some(result) => println(result)
      case None => println("Not found")
    }

    i = 0
    val result3 = findDoWhile[Int]({i += 1; i < 10}) {break =>
      if(i == 5) break(i)
    }
    result3 match {
      case Some(result) => println(result)
      case None => println("Not found")
    }

    val result4 = findFor[String, String](
      Array("aaa", "bbb", "ccc")) {(value, break) =>
      if(value == "ddd")
        break(value)
    }
    println(result4)

    val result5 = findFor[String,String](Array("aaa", "bbb", "ccc"))
    {(value, break) =>
      if(value == "bbb")
        break(value)
    } match {
      case Some(result) => println(result)
      case None => println("Not found")
    }

    val result6 = findFor[Int,Int](1 to 10) {(i, break) =>
      if(i % 2 == 1) break(i)
    }
    result6 match {
      case Some(result) => println(result)
      case None => println("Not found")
    }
  }
}