scala.collection.immutable

class Tree

[source: scala/collection/immutable/Tree.scala]

@serializable

abstract class Tree[A, B](implicit view$0 : (A) => Ordered[A])
extends AnyRef

General Balanced Trees - highly efficient functional dictionaries.

An efficient implementation of Prof. Arne Andersson's General Balanced Trees. These have no storage overhead compared to plain unbalanced binary trees, and their performance is in general better than AVL trees.

This implementation does not balance the trees after deletions. Since deletions don't increase the height of a tree, this should be OK in most applications. A balance method is provided for those cases where rebalancing is needed.

The tree consists of entries conatining a key with an order.

When instanciating the tree an order for the keys has to be supplied.

Author
Erik Stenman, Michel Schinz
Version
1.1, 2005-01-20
Type Summary
protected abstract type This <: Tree[A, B]
The type returned when creating a new tree. This type should be defined by concrete implementations e.g.
    class C[T](...) extends Tree[A,B](...) {
      type This = C[T];
    
protected type aNode
The type of nodes that the tree is build from.
Method Summary
protected abstract def New (sz : Int, t : GBTree) : This

This abstract method should be defined by a concrete implementation C[T] as something like:

      override def New(sz: Int, t: aNode): This {
        new C[T](order) {
          override def size = sz
          override protected def tree: aNode = t
      }
    

The concrete implementation should also override the def of This override type This = C[T];

protected def add (key : A, entry : B) : This
A new tree with the entry added is returned, assuming that key is not in the tree.
def balance : This
Create a new balanced tree from the tree. Might be useful to call after many deletions, since deletion does not rebalance the tree.
protected def deleteAny (key : A) : This
Removes the key from the tree.
protected def entries : Iterator[B]
Gives you an iterator over all elements in the tree. The iterator structure corresponds to the call stack of an in-order traversal. Note: The iterator itself has a state, i.e., it is not functional.
protected def findValue (key : A) : Option[B]
Check if this map maps key to a value and return the value if it exists.
protected abstract def getThis : This
def size : Int
The size of the tree, returns 0 (zero) if the tree is empty.
protected def tree : GBTree
The nodes in the tree.
protected def updateOrAdd (key : A, entry : B) : This
A new tree with the entry added is returned, if key is not in the tree, otherwise the key is updated with the new entry.
Methods inherited from AnyRef
getClass, hashCode, equals, clone, toString, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized
Methods inherited from Any
==, !=, isInstanceOf, asInstanceOf
Type Details
protected abstract type This <: Tree[A, B]
The type returned when creating a new tree. This type should be defined by concrete implementations e.g.
    class C[T](...) extends Tree[A,B](...) {
      type This = C[T];
    

protected type aNode
The type of nodes that the tree is build from.

Method Details
protected abstract def getThis : This

protected def tree : GBTree
The nodes in the tree.

protected abstract def New(sz : Int, t : GBTree) : This

This abstract method should be defined by a concrete implementation C[T] as something like:

      override def New(sz: Int, t: aNode): This {
        new C[T](order) {
          override def size = sz
          override protected def tree: aNode = t
      }
    

The concrete implementation should also override the def of This override type This = C[T];


def size : Int
The size of the tree, returns 0 (zero) if the tree is empty.
Returns
The number of nodes in the tree as an integer.

protected def add(key : A, entry : B) : This
A new tree with the entry added is returned, assuming that key is not in the tree.
Parameters
key - ...
entry - ...
Returns
...

protected def updateOrAdd(key : A, entry : B) : This
A new tree with the entry added is returned, if key is not in the tree, otherwise the key is updated with the new entry.

protected def deleteAny(key : A) : This
Removes the key from the tree.
Parameters
key - ...
Returns
...

protected def findValue(key : A) : Option[B]
Check if this map maps key to a value and return the value if it exists.
Parameters
key - the key of the mapping of interest
Returns
the value of the mapping, if it exists

protected def entries : Iterator[B]
Gives you an iterator over all elements in the tree. The iterator structure corresponds to the call stack of an in-order traversal. Note: The iterator itself has a state, i.e., it is not functional.

def balance : This
Create a new balanced tree from the tree. Might be useful to call after many deletions, since deletion does not rebalance the tree.