Scala example source code file (viewtest1.scala)

This example Scala source code file (viewtest1.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

array, boolean, empty, empty, list, node, node, o, ordered, ordered, string, test, tree, tree

The Scala viewtest1.scala source code

package test

trait Ordered[a] {
  def < (x: a): Boolean
}

object O {
  implicit def view (x: String): Ordered[String] = new Ordered[String] {
    def < (y: String) = x.compareTo(y) < 0
  }
}

object Empty extends Tree[Nothing]
case class Node[c <% Ordered[c]](elem: c, l: Tree[c], r: Tree[c]) extends Tree[c]

abstract class Tree[+a <% Ordered[a]] {
  def insert[b >: a <% Ordered[b]](x: b): Tree[b] = this match {
    case Empty =>
      new Node(x, Empty, Empty)
    case Node(elem, l, r) =>
      if (x == elem) this
      else if (x < elem) Node(elem, l insert x, r)
      else Node(elem, l, r insert x)
  }
  def elements: List[a] = this match {
    case Empty => List()
    case Node(elem, l, r) =>
      l.elements ::: List(elem) ::: r.elements
  }
}

object Test {
  import O.view

  def main(args: Array[String]) {
    var t: Tree[String] = Empty
    for (s <- args) {
      t = t insert s
    }
    println(t.elements)
  }
}