package scala.collection
package immutable
import generic._
import mutable.{ Builder, SetBuilder }
object TreeSet extends ImmutableSortedSetFactory[TreeSet] {
implicit def implicitBuilder[A](implicit ordering: Ordering[A]): Builder[A, TreeSet[A]] = newBuilder[A](ordering)
override def newBuilder[A](implicit ordering: Ordering[A]): Builder[A, TreeSet[A]] =
new SetBuilder(empty[A](ordering))
def empty[A](implicit ordering: Ordering[A]) = new TreeSet[A]
}
@SerialVersionUID(-234066569443569402L)
class TreeSet[A](override val size: Int, t: RedBlack[A]#Tree[Unit])
(implicit val ordering: Ordering[A])
extends RedBlack[A] with SortedSet[A] with SortedSetLike[A, TreeSet[A]] with Serializable {
override def stringPrefix = "TreeSet"
def isSmaller(x: A, y: A) = compare(x,y) < 0
def this()(implicit ordering: Ordering[A]) = this(0, null)(ordering)
protected val tree: RedBlack[A]#Tree[Unit] = if (size == 0) Empty else t
private def newSet(s: Int, t: RedBlack[A]#Tree[Unit]) = new TreeSet[A](s, t)
override def empty = TreeSet.empty
def + (elem: A): TreeSet[A] = {
val newsize = if (tree.lookup(elem).isEmpty) size + 1 else size
newSet(newsize, tree.update(elem, ()))
}
def insert(elem: A): TreeSet[A] = {
assert(tree.lookup(elem).isEmpty)
newSet(size + 1, tree.update(elem, ()))
}
def - (elem:A): TreeSet[A] =
if (tree.lookup(elem).isEmpty) this
else newSet(size - 1, tree delete elem)
def contains(elem: A): Boolean = !tree.lookup(elem).isEmpty
def iterator: Iterator[A] = tree.toStream.iterator map (_._1)
override def toStream: Stream[A] = tree.toStream map (_._1)
override def foreach[U](f: A => U) = tree foreach { (x, y) => f(x) }
override def rangeImpl(from: Option[A], until: Option[A]): TreeSet[A] = {
val tree = this.tree.range(from, until)
newSet(tree.count, tree)
}
override def firstKey = tree.first
override def lastKey = tree.last
}