Insertion-ordered ListSet

Question

ListSet (collection.immutable.ListSet) is a inverse ordered set. I need ordered set. This is a example of original ListSet:

var a = ListSet(1,2,3)
var ite = a.iterator
ite.next // returns 3
ite.next // returns 2
ite.next // returns 1

And this is a example of I need:

var a = ListSet(1,2,3)
var ite = a.iterator
ite.next // returns 1
ite.next // returns 2
ite.next // returns 3

UPDATE:

"Ordered" is a "Insertion Ordered" for me. I need this:

var a = ListSet(1,2,3)
a += 5
a += 4
var ite = a.iterator
ite.next // returns 1
ite.next // returns 2
ite.next // returns 3
ite.next // returns 5
ite.next // returns 4

Answer 1

collection.mutable.LinkedHashSet is a set that iterates its members in the same sequence they were inserted. (I avoid the term "ordered" here, since I prefer to reserve that to cases of an ordering relation on the values, not the particular sequence in which some actions were carried out.)

Answer 2

var eti = a.toList.reverse.iterator

Answer 3

It is not ordered:

val a = ListSet(3,1,2)
val ite = a.iterator
ite.next // returns 2
ite.next // returns 1
ite.next // returns 3