Grouping an iterator by a predicate

grouping.scala

class IteratorW[A](itr: Iterator[A]) {
  def groupWhen(fn: A => Boolean): Iterator[Seq[A]] = new Iterator[Seq[A]] {
    private val bitr = itr.buffered
    override def hasNext = bitr.hasNext
    override def next = {
      val xs = collection.mutable.ListBuffer(bitr.next)
      while (bitr.hasNext && !fn(bitr.head)) xs += bitr.next
      xs.toSeq
    }
  }
}
implicit def ToIteratorW[A](itr: Iterator[A]): IteratorW[A] = new IteratorW(itr)

val everyTen = (1 to 100).iterator groupWhen { _ % 10 == 1 }
everyTen foreach println

See http://stackoverflow.com/questions/6800737/how-to-group-a-variable-length-repeating-sequence-in-scala for other implementations.