unzip(3) on view now returns view.

* Added unzip and unzip3 to TraversableViewLike
* Added partest tests for unzip on views returning specific collection types.

Closes SI-5053
Review by @paulp

3 files changed, 32 insertions, 0 deletions

diff --git a/src/library/scala/collection/TraversableViewLike.scala b/src/library/scala/collection/TraversableViewLike.scala
index 60870cc835..fbecad98fe 100644
--- a/src/library/scala/collection/TraversableViewLike.scala
+++ b/src/library/scala/collection/TraversableViewLike.scala
@@ -192,6 +192,12 @@ trait TraversableViewLike[+A,
   override def groupBy[K](f: A => K): immutable.Map[K, This] =
     thisSeq groupBy f mapValues (xs => newForced(xs))
 
+  override def unzip[A1, A2](implicit asPair: A => (A1, A2)) =
+    (newMapped(x => asPair(x)._1), newMapped(x => asPair(x)._2))  // TODO - Performance improvements.
+
+  override def unzip3[A1, A2, A3](implicit asTriple: A => (A1, A2, A3)) =
+    (newMapped(x => asTriple(x)._1), newMapped(x => asTriple(x)._2), newMapped(x => asTriple(x)._3))  // TODO - Performance improvements.
+
   override def toString = viewToString
 }
 
diff --git a/test/files/run/t5053.check b/test/files/run/t5053.check
new file mode 100644
index 0000000000..5ec39bbdeb
--- /dev/null
+++ b/test/files/run/t5053.check
@@ -0,0 +1,6 @@
+true
+true
+true
+true
+true
+true
diff --git a/test/files/run/t5053.scala b/test/files/run/t5053.scala
new file mode 100644
index 0000000000..e46dad5ac6
--- /dev/null
+++ b/test/files/run/t5053.scala
@@ -0,0 +1,20 @@
+object Test extends App {
+  {
+    val (left, right) = Seq((1, "a"), (1, "a"), (1, "a"), (3, "c")).view.unzip
+    println(left.isInstanceOf[scala.collection.SeqViewLike[_,_,_]])
+    val (l, m, r) = Seq((1, 1.0, "a"), (1, 1.0, "a"), (1, 1.0, "a"), (3, 3.0, "c")).view.unzip3
+    println(l.isInstanceOf[scala.collection.SeqViewLike[_,_,_]])  
+  }
+  {
+    val (left, right) = Iterable((1, "a"), (1, "a"), (1, "a"), (3, "c")).view.unzip
+    println(left.isInstanceOf[scala.collection.IterableViewLike[_,_,_]])
+    val (l, m, r) = Iterable((1, 1.0, "a"), (1, 1.0, "a"), (1, 1.0, "a"), (3, 3.0, "c")).view.unzip3
+    println(l.isInstanceOf[scala.collection.IterableViewLike[_,_,_]])  
+  }
+  {
+    val (left, right) = Traversable((1, "a"), (1, "a"), (1, "a"), (3, "c")).view.unzip
+    println(left.isInstanceOf[scala.collection.TraversableViewLike[_,_,_]])
+    val (l, m, r) = Traversable((1, 1.0, "a"), (1, 1.0, "a"), (1, 1.0, "a"), (3, 3.0, "c")).view.unzip3
+    println(l.isInstanceOf[scala.collection.TraversableViewLike[_,_,_]])  
+  }
+}