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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection.immutable
/** The canonical factory of <a href="TreeSet.html">TreeSet</a>'s. */
object TreeSet {
/** The empty set of this type
*/
def empty[A <% Ordered[A]] = new TreeSet[A]
/** The canonical factory for this type
*/
def apply[A <% Ordered[A]](elems: A*) : SortedSet[A] = empty[A] ++ elems
}
/** This class implements immutable sets using a tree.
*
* @author Martin Odersky
* @version 2.0, 02/01/2007
*/
@serializable
class TreeSet[A <% Ordered[A]](val size: Int, t: RedBlack[A]#Tree[Unit])
extends RedBlack[A] with SortedSet[A] {
def isSmaller(x: A, y: A) = x < y
def this() = this(0, null)
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 maps of the same type of keys.
*/
def empty[B]: Set[B] = ListSet.empty[B]
/** 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 elements: Iterator[A] = tree.elements.elements map (_._1)
def elementsSlow = tree.elementsSlow map (_._1)
override def foreach(f: A => Unit) {
tree.visit[Unit](())((unit0, y, unit1) => Tuple2(true, f(y)))
}
override def forall(f: A => Boolean): Boolean =
tree.visit[Boolean](true)((input, a, unit) => f(a) match {
case ret if input => Tuple2(ret, ret)
})._2
override def exists(f: A => Boolean): Boolean =
tree.visit[Boolean](false)((input, a, unit) => f(a) match {
case ret if !input => Tuple2(!ret, ret)
})._2
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
override def compare(a0: A, a1: A) = a0.compare(a1)
}
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