diff options
Diffstat (limited to 'src/library/scala/collection/immutable/MapLike.scala')
| -rw-r--r-- | src/library/scala/collection/immutable/MapLike.scala | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/src/library/scala/collection/immutable/MapLike.scala b/src/library/scala/collection/immutable/MapLike.scala index fb2826b4df..beea72d676 100644 --- a/src/library/scala/collection/immutable/MapLike.scala +++ b/src/library/scala/collection/immutable/MapLike.scala @@ -116,7 +116,16 @@ trait MapLike[A, +B, +This <: MapLike[A, B, This] with Map[A, B]] /** Collects all keys of this map in a set. * @return a set containing all keys of this map. */ - override def keySet: immutable.Set[A] = immutable.Set.empty ++ (this map (_._1)) + override def keySet: immutable.Set[A] = new ImmutableDefaultKeySet + + protected class ImmutableDefaultKeySet extends super.DefaultKeySet with immutable.Set[A] { + override def + (elem: A): immutable.Set[A] = + if (this(elem)) this + else immutable.Set[A]() ++ this + elem + override def - (elem: A): immutable.Set[A] = + if (this(elem)) immutable.Set[A]() ++ this - elem + else this + } /** This function transforms all the values of mappings contained * in this map with function `f`. |