/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection.immutable
import scala.collection.generic._
/** The canonical factory of <a href="TreeSet.html">TreeSet</a>'s. */
object TreeSet extends SortedSetFactory[TreeSet]{
implicit def implicitBuilder[A](implicit ordering : Ordering[A]) : Builder[A, TreeSet[A]] = newBuilder[A](ordering)
def newBuilder[A](implicit ordering : Ordering[A]) : Builder[A, TreeSet[A]] = new AddingBuilder(empty[A](ordering))
/** The empty set of this type
*/
def empty[A](implicit ordering : Ordering[A]) = new TreeSet[A]
}
/** This class implements immutable sets using a tree.
*
* @author Martin Odersky
* @version 2.0, 02/01/2007
*/
@serializable
class TreeSet[A](override val size: Int, t: RedBlack[A]#Tree[Unit])(implicit val ordering : Ordering[A])
extends RedBlack[A] with SortedSet[A] with SortedSetTemplate[A, TreeSet[A]] {
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)
/** A factory to create empty sets of the same type of keys.
*/
override def empty = TreeSet.empty
/** A new TreeSet with the entry added is returned,
*/
def + (elem: A): TreeSet[A] = {
val newsize = if (tree.lookup(elem).isEmpty) size + 1 else size
newSet(newsize, tree.update(elem, ()))
}
/** A new TreeSet with the entry added is returned,
* assuming that elem is <em>not</em> in the TreeSet.
*/
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))
/** Checks if this set contains element <code>elem</code>.
*
* @param elem the element to check for membership.
* @return true, iff <code>elem</code> is contained in this set.
*/
def contains(elem: A): Boolean = !tree.lookup(elem).isEmpty
/** Creates a new iterator over all elements contained in this
* object.
*
* @return the new iterator
*/
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
}