Adding special take and drop for numeric ranges...

Adding special take and drop for numeric ranges, and a test. Parallel
numeric ranges are added, but currently disabled.

Review by extempore.

1 files changed, 15 insertions, 1 deletions

diff --git a/src/library/scala/collection/immutable/NumericRange.scala b/src/library/scala/collection/immutable/NumericRange.scala
index fb5c7221dc..a548b62533 100644
--- a/src/library/scala/collection/immutable/NumericRange.scala
+++ b/src/library/scala/collection/immutable/NumericRange.scala
@@ -42,7 +42,7 @@ import generic._
 abstract class NumericRange[T]
   (val start: T, val end: T, val step: T, val isInclusive: Boolean)
   (implicit num: Integral[T])
-extends IndexedSeq[T] with Serializable {
+extends IndexedSeq[T] with Parallelizable[parallel.immutable.ParNumericRange[T]] with Serializable {
   /** Note that NumericRange must be invariant so that constructs
    *  such as "1L to 10 by 5" do not infer the range type as AnyVal.
    */
@@ -57,6 +57,8 @@ extends IndexedSeq[T] with Serializable {
     if (length == 0) Nil.last
     else locationAfterN(length - 1)
 
+  def par = new parallel.immutable.ParNumericRange(this)
+
   /** Create a new range with the start and end values of this range and
    *  a new `step`.
    */
@@ -107,6 +109,18 @@ extends IndexedSeq[T] with Serializable {
   // based on the given value.
   private def newEmptyRange(value: T) = NumericRange(value, value, step)
 
+  final override def take(n: Int): NumericRange[T] = (
+    if (n <= 0 || length == 0) newEmptyRange(start)
+    else if (n >= length) this
+    else new NumericRange.Inclusive(start, locationAfterN(n - 1), step)
+  )
+
+  final override def drop(n: Int): NumericRange[T] = (
+    if (n <= 0 || length == 0) this
+    else if (n >= length) newEmptyRange(end)
+    else copy(locationAfterN(n), end, step)
+  )
+
   def apply(idx: Int): T = {
     if (idx < 0 || idx >= length) throw new IndexOutOfBoundsException(idx.toString)
     else locationAfterN(idx)