diff options
| -rw-r--r-- | src/library/scala/collection/immutable/Range.scala | 16 | ||||
| -rw-r--r-- | test/files/run/bug3529.scala | 12 |
2 files changed, 22 insertions, 6 deletions
diff --git a/src/library/scala/collection/immutable/Range.scala b/src/library/scala/collection/immutable/Range.scala index cef043555f..930b007389 100644 --- a/src/library/scala/collection/immutable/Range.scala +++ b/src/library/scala/collection/immutable/Range.scala @@ -87,6 +87,9 @@ class Range(val start: Int, val end: Int, val step: Int) extends IndexedSeq[Int] } // take and drop have to be tolerant of large values without overflowing + // warning! this is buggy, and gives wrong answers on boundary cases. + // The known bugs are avoided by drop not calling it in those cases. + // See ticket #3529. It should be revised. private def locationAfterN(n: Int) = if (n > 0) { if (step > 0) ((start.toLong + step.toLong * n.toLong) min last.toLong).toInt @@ -103,11 +106,11 @@ class Range(val start: Int, val end: Int, val step: Int) extends IndexedSeq[Int] * @param n the number of elements to take. * @return a new range consisting of `n` first elements. */ - final override def take(n: Int): Range = if (n > 0 && length > 0) { - Range(start, locationAfterN(n - 1), step).inclusive - } else { - Range(start, start, step) - } + final override def take(n: Int): Range = + if (n > 0 && length > 0) + Range(start, locationAfterN(n - 1), step).inclusive + else + Range(start, start, step) /** Creates a new range containing all the elements of this range except the first `n` elements. * @@ -117,7 +120,8 @@ class Range(val start: Int, val end: Int, val step: Int) extends IndexedSeq[Int] * @return a new range consisting of all the elements of this range except `n` first elements. */ final override def drop(n: Int): Range = - copy(locationAfterN(n), end, step) + if (n >= length) copy(end + 1, end, step) + else copy(locationAfterN(n), end, step) /** Creates a new range containing all the elements of this range except the last one. * diff --git a/test/files/run/bug3529.scala b/test/files/run/bug3529.scala new file mode 100644 index 0000000000..4d83bcfa22 --- /dev/null +++ b/test/files/run/bug3529.scala @@ -0,0 +1,12 @@ +object Test { + def main(args: Array[String]): Unit = { + assert(1 to 10 drop 10 isEmpty) + assert(1 until 10 drop 9 isEmpty) + assert(1 to 10 by 2 drop 5 isEmpty) + + assert((1 to 10 drop 9) == Seq(10)) + assert((1 until 10 drop 9) == Nil) + + assert(Stream(1 to 10).flatten.toList == Stream(1 until 11).flatten.toList) + } +} |