diff options
Diffstat (limited to 'src/library/scala/collection/Iterator.scala')
| -rw-r--r-- | src/library/scala/collection/Iterator.scala | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/src/library/scala/collection/Iterator.scala b/src/library/scala/collection/Iterator.scala index 1b496383a3..f6f46e158f 100644 --- a/src/library/scala/collection/Iterator.scala +++ b/src/library/scala/collection/Iterator.scala @@ -922,11 +922,16 @@ trait Iterator[+A] extends TraversableOnce[A] { /** For reasons which remain to be determined, calling * self.take(n).toSeq cause an infinite loop, so we have * a slight variation on take for local usage. + * NB: self.take.toSeq is slice.toStream, lazily built on self, + * so a subsequent self.hasNext would not test self after the + * group was consumed. */ private def takeDestructively(size: Int): Seq[A] = { val buf = new ArrayBuffer[A] var i = 0 - while (self.hasNext && i < size) { + // The order of terms in the following condition is important + // here as self.hasNext could be blocking + while (i < size && self.hasNext) { buf += self.next i += 1 } @@ -943,12 +948,10 @@ trait Iterator[+A] extends TraversableOnce[A] { // so the rest of the code can be oblivious val xs: Seq[B] = { val res = takeDestructively(count) - // extra checks so we don't calculate length unless there's reason - if (pad.isDefined && !self.hasNext) { - val shortBy = count - res.length - if (shortBy > 0) res ++ padding(shortBy) else res - } - else res + // was: extra checks so we don't calculate length unless there's reason + // but since we took the group eagerly, just use the fast length + val shortBy = count - res.length + if (shortBy > 0 && pad.isDefined) res ++ padding(shortBy) else res } lazy val len = xs.length lazy val incomplete = len < count |