PitTree.scala

import scala.collection.Map

class PitTree[+T](val children : Map[String, PitTree[T]], val value : Option[T]) extends Map[String, T] {
  def this() = this(Map(), None)
  def this(value : T) = this(Map(), Some(value))
  
  def update[T1 >: T](path : String, upVal : T1) : PitTree[T1] = this.+(path -> upVal)
  
  override def empty = new PitTree[T]

  def get(path : String) : Option[T] = get(splitPath(path))
  def get(path : List[String]) : Option[T] = path match {
    case Nil =>
      	value
    case h :: t =>
      	if(children.keysIterator.exists(_ == h))
      		children(h).get(t)
        else
        	None
  }
  def +[T1 >: T](that: PitTree[T1]) : PitTree[T1] = {
	  val newChildren = that.children.foldLeft(children.asInstanceOf[Map[String, PitTree[T1]]])((acc, kv) => children.get(kv._1) match {
	 	  case Some(exists) => acc + (kv._1 -> (exists + kv._2))
	 	  case None => acc + (kv._1 -> kv._2)
	  })
	  new PitTree[T1](newChildren, value)
  }
  def +[T1 >: T](kv: (String, T1)): PitTree[T1] = this.+(splitPath(kv._1), kv._2)
  def +[T1 >: T](path : List[String], upVal : T1) : PitTree[T1] = path match {
    case Nil =>
      new PitTree[T1](upVal)
    case h :: t =>
      val child = children.getOrElse(h, new PitTree[T1]()).+(t, upVal)
      new PitTree[T1](children + (h -> child), value)
  }
  def - (key: String): PitTree[T] = throw new RuntimeException("Not yet implemented")
  def iterator : Iterator[(String, T)] = {
	  def getIt(prefix : String, tree : PitTree[T], acc: List[(String, T)]) : List[(String, T)] = {
	 	  tree.children.foldLeft(acc)((acc2, kv) => {
	 		  val path = prefix + "/" + kv._1
	 		  val subTree = kv._2
	 		  if (kv._2.value.isDefined)
	 			  getIt(path, subTree, (path, kv._2.value.get) :: acc2)
	 	      else
	 	    	  getIt(path, subTree, acc2)
	 	  })
	  }
	  getIt("", this, List()).iterator
  }
  
  def splitPath(path : String) = path.split('/').filter(_ != "").toList
  
  def filterPath(filter : String) = { 
	  (PitTree[T]() /: filter.split(";")){(tree, expression) =>
	   	tree + this.filter(((kv)) => kv._1.contains(expression)).asInstanceOf[PitTree[T]]
	   }
  }

  override def toString = ".\n"+toString(children.toList, "", "")

  def toString[T1 >: T](children: List[(String, PitTree[T1])], prefix: String, name: String): String = {
    def formatValue(o: Option[T1]): String = o match {
      case Some(s) => "= " + s.toString
      case None => ""
    }
    children match {
      case Nil => ""
      case h::Nil => // last element
        val (name, subTree) = h
       prefix + "`-- " + name + " " + formatValue(subTree.value) + "\n" +
         toString(subTree.children.toList, prefix + " ", name)
      case h::t =>
       val (name, subTree) = h
       prefix + "|-- " + name + " " + formatValue(subTree.value) + "\n" +
         toString(subTree.children.toList, prefix + "| ", name) +
         toString(t, prefix, name)
    }
  }
}

object PitTree {
  def apply[T]() = new PitTree[T]()
  def apply[T](value : T) = new PitTree[T](value)
}

object Test extends Application {  
	  var pitTree = PitTree[Int]()
	  pitTree = pitTree("/apa") = 10
	  pitTree = pitTree("/apa") = 20
	  pitTree = pitTree("gris/kossa/häst") = 30
	  pitTree = pitTree("gris/kossa/apa") = 10
	  pitTree = pitTree("gris/kossa/katt/firre") = 4
	  pitTree = pitTree("flodhaest") = 2
	  println(pitTree)
  //TODO: Add example with comments showing results of operations.
}

tostring

.
|-- apa = 20
|-- gris 
| `-- kossa 
|  |-- häst = 30
|  |-- apa = 10
|  `-- katt 
|   `-- firre = 4
`-- flodhaest = 2