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/* NSC -- new Scala compiler
* Copyright 2005-2009 LAMP/EPFL
* @author Martin Odersky
*/
// $Id$
package scala.tools.nsc.util
/** Sets implemented as binary trees.
*
* @author Martin Odersky
* @version 1.0
*/
class TreeSet[T >: Null <: AnyRef](less: (T, T) => Boolean) extends Set[T] {
private class Tree(val elem: T) {
var l: Tree = null
var r: Tree = null
}
private var tree: Tree = null
def findEntry(x: T): T = {
def find(t: Tree): T = {
if (t eq null) null
else if (less(x, t.elem)) find(t.l)
else if (less(t.elem, x)) find(t.r)
else t.elem
}
find(tree)
}
def addEntry(x: T) {
def add(t: Tree): Tree = {
if (t eq null) new Tree(x)
else if (less(x, t.elem)) { t.l = add(t.l); t }
else if (less(t.elem, x)) { t.r = add(t.r); t }
else t
}
tree = add(tree)
}
def elements = {
def elems(t: Tree): Iterator[T] = {
var it = Iterator.single(t.elem)
if (t.l ne null) it = elems(t.l) append it
if (t.r ne null) it = it append elems(t.r)
it
}
if (tree eq null) Iterator.empty else elems(tree)
}
override def toString(): String = {
if (tree eq null) "<empty>" else "(..." + tree.elem + "...)"
}
}
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