review part I

Author: Jasper-M

library/src/scala/collection/Iterator.scala

@@ -129,7 +129,11 @@ trait Iterator[+A] extends IterableOnce[A] with IterableOnceOps[A, Iterator, Ite
  hd
  }
 
- override def knownSize = self.knownSize + (if (hdDefined) 1 else 0)
+ override def knownSize = {
+ val thisSize = self.knownSize
+ if (thisSize >= 0 && hdDefined) thisSize + 1
+ else thisSize
+ }
 
  def hasNext =
  hdDefined || self.hasNext
@@ -811,7 +815,7 @@ trait Iterator[+A] extends IterableOnce[A] with IterableOnceOps[A, Iterator, Ite
 
  def zipWithIndex: Iterator[(A, Int)] = new AbstractIterator[(A, Int)] {
  var idx = 0
- override def knownSize = -1 max self.knownSize
+ override def knownSize = self.knownSize
  def hasNext = self.hasNext
  def next() = {
  val ret = (self.next(), idx)
@@ -1201,7 +1205,11 @@ object Iterator extends IterableFactory[Iterator] {
  override def knownSize: Int = {
  val size = underlying.knownSize
  if (size < 0) -1
- else remaining min ((size - dropping) max 0)
+ else {
+ val dropSize = 0 max (size - dropping)
+ if (unbounded) dropSize
+ else remaining min dropSize
+ }
  }
  def hasNext = { skip(); remaining != 0 && underlying.hasNext }
  def next() = {