とりあえず（？）作ってみた。（手荷物一時預かり 編）その４。

東方算程譚:手荷物一時預かり
Cloak クラス。こんなんでいいのかな･･･ほんとにもぅｗ

Public Class Cloak


  Private tags As [Set](Of Integer)


  Public Sub New()
    tags = New [Set](Of Integer)
    tags.Insert(0)
  End Sub


  Public Function Peek() As Integer
    Dim iter As [Set](Of Integer).Iterator = tags.Find(0)

    Dim minValue As Integer = tags.Begin.Current
    If iter.Current = minValue Then
      Dim acquiredMaxValue As Integer = tags.RBegin.Current
      Return acquiredMaxValue + 1
    Else
      iter -= 1
      Return Math.Abs(iter.Current)
    End If
  End Function


  Public Function Acquire() As Integer
    Dim n As Integer = Me.Peek()
    Me.tags.Erace(-n)

    Me.tags.Insert(n)
    Return n
  End Function


  Public Function Release(ByVal n As Integer) As Boolean
    If Me.tags.Erace(n) Then
      Return Me.tags.Insert(-n)
    Else
      Return False
    End If
  End Function


  Public Sub Clear()
    Me.tags.Clear()
  End Sub


  Public Function Acquired() As List(Of Integer)
    Dim result As New List(Of Integer)
    Dim iter As [Set](Of Integer).Iterator = Me.tags.RBegin
    While iter.Current > 0
      result.Add(iter.Current)
      iter.MoveNext()
    End While
    Return result
  End Function


  Public Function Released() As List(Of Integer)
    Dim result As New List(Of Integer)
    Dim iter As [Set](Of Integer).Iterator = Me.tags.Begin
    While iter.Current < 0
      result.Add(Math.Abs(iter.Current))
      iter.MoveNext()
    End While
    Return result
  End Function


End Class