Made Iterator consistent with Iterable by addin...

Made Iterator consistent with Iterable by adding grouped and sliding to
IterableLike. Closes #2837. Review by community.

1 files changed, 32 insertions, 0 deletions

diff --git a/src/library/scala/collection/IterableLike.scala b/src/library/scala/collection/IterableLike.scala
index 2e86b90479..8446988821 100644
--- a/src/library/scala/collection/IterableLike.scala
+++ b/src/library/scala/collection/IterableLike.scala
@@ -138,6 +138,38 @@ self =>
     b.result
   }
 
+  /** Partitions elements in fixed size ${coll}s.
+   *  @see Iterator#grouped
+   *
+   *  @param size the number of elements per group
+   *  @return An iterator producing ${coll}s of size `size`, except the
+   *          last will be truncated if the elements don't divide evenly.
+   */
+  def grouped(size: Int): Iterator[Repr] =
+    for (xs <- iterator grouped size) yield {
+      val b = newBuilder
+      b ++= xs
+      b.result
+    }
+
+  /** Groups elements in fixed size blocks by passing a "sliding window"
+   *  over them (as opposed to partitioning them, as is done in grouped.)
+   *  @see Iterator#sliding
+   *
+   *  @param size the number of elements per group
+   *  @param step the distance between the first elements of successive
+   *         groups (defaults to 1)
+   *  @return An iterator producing ${coll}s of size `size`, except the
+   *          last will be truncated if the elements don't divide evenly.
+   */
+  def sliding[B >: A](size: Int): Iterator[Repr] = sliding(size, 1)
+  def sliding[B >: A](size: Int, step: Int): Iterator[Repr] =
+    for (xs <- iterator.sliding(size, step)) yield {
+      val b = newBuilder
+      b ++= xs
+      b.result
+    }
+
   /** Selects last ''n'' elements.
    *  $orderDependent
    *