Sedgewick binary tree

Sedgewick_binary_tree.fs

// Write code or load a sample from sidebar
open Fable
open Fable.Core
open Fable.Core.JS

[<AllowNullLiteralAttribute>]
type Node<'Key , 'Value when 'Key :> System.IComparable<'Key>>(key: 'Key, value : 'Value , N : int) = 
  member _.Key = key
  member val Value = value with get, set
  member val N = N  with get, set
  member val Left : Node<'Key,'Value> = Unchecked.defaultof<_> with get, set
  member val Right : Node<'Key,'Value>  = Unchecked.defaultof<_> with get, set
  

type BinarySearchST<'Key, 'Value when 'Key :> System.IComparable<'Key>> () =  

  [<DefaultValue>] val mutable root : Node<'Key,'Value>

  member this.Size() = this.Size(this.root)

  member this.Size(x : Node<'Key,'Value>)= 
    if x |> isNull then 0
    else x.N

  member private this.Put (x : Node<'Key,'Value>, key:'Key , value:'Value) = 
    if x |> isNull then Node( key , value, 1)
    else
      let cmp = key.CompareTo(x.Key)
      if cmp < 0 then x.Left <- this.Put(x.Left, key, value) 
      else if cmp > 0 then x.Right <- this.Put(x.Right, key, value)
      else x.Value <- value;
      x.N <- this.Size(x.Left) + this.Size(x.Right) + 1
      x

  member this.Put(key : 'Key, value : 'Value)
    = this.root <- this.Put(this.root, key, value)
  member this.Get(key : 'Key) =
    this.Get(this.root,key)

  member this.Get(x : Node<'Key,'Value>, key : 'Key) : 'Value = 
    if x |> isNull then Unchecked.defaultof<'Value>
    else
      let cmp = key.CompareTo(x.Key)
      if cmp < 0 then this.Get(x.Left, key);
      else if (cmp > 0) then this.Get(x.Right, key)
      else x.Value