From 266a2ca1c4ed1c655989c2435a9e83650b06f79a Mon Sep 17 00:00:00 2001 From: Paul Phillips Date: Tue, 4 Jan 2011 01:17:05 +0000 Subject: Modified generic companion apply to call empty ... Modified generic companion apply to call empty if there are no arguments, so something like Set() does not generate unnecessary garbage. Also found some immutable classes which don't reuse an empty object for emptiness, and gave them one. No review. --- src/library/scala/collection/immutable/ListSet.scala | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'src/library/scala/collection/immutable/ListSet.scala') diff --git a/src/library/scala/collection/immutable/ListSet.scala b/src/library/scala/collection/immutable/ListSet.scala index 8547ba195b..ec0f2ff5a1 100644 --- a/src/library/scala/collection/immutable/ListSet.scala +++ b/src/library/scala/collection/immutable/ListSet.scala @@ -23,9 +23,11 @@ import mutable.{ ListBuffer, Builder } object ListSet extends ImmutableSetFactory[ListSet] { /** setCanBuildFromInfo */ implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ListSet[A]] = setCanBuildFrom[A] - override def empty[A] = new ListSet[A] + override def empty[A] = EmptyListSet.asInstanceOf[ListSet[A]] override def newBuilder[A]: Builder[A, ListSet[A]] = new ListSetBuilder[A] + private object EmptyListSet extends ListSet[Any] { } + /** A custom builder because forgetfully adding elements one at * a time to a list backed set puts the "squared" in N^2. There is a * temporary space cost, but it's improbable a list backed set could -- cgit v1.2.3