Index: sdk/lib/_collection_dev/iterable.dart |
diff --git a/sdk/lib/_collection_dev/iterable.dart b/sdk/lib/_collection_dev/iterable.dart |
index 7510273a20e9720c13f08b1220589447b98d7ba0..ac490e1cf2fcc0905861db486a773856ae047e64 100644 |
--- a/sdk/lib/_collection_dev/iterable.dart |
+++ b/sdk/lib/_collection_dev/iterable.dart |
@@ -683,3 +683,8 @@ class EmptyIterator<E> implements Iterator<E> { |
bool moveNext() => false; |
E get current => null; |
} |
+ |
+/** An [Iterator] that can move in both directions. */ |
+abstract class BiDirectionalIterator<T> implements Iterator<T> { |
+ bool movePrevious(); |
+} |