Generic Stack : Generic Stack « Generics « VB.Net Tutorial

1. VB.Net Tutorial
2. Generics
3. Generic Stack

Module StackTest
   Dim doubleElements() As Double = {1.1, 2.2, 3.3, 4.4, 5.5, 6.6}
   Dim integerElements() As Integer = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}

   Dim doubleStack As Stack(Of Double)
   Dim integerStack As Stack(Of Integer)

   Sub Main()
      doubleStack = New Stack(Of Double)(5)
      integerStack = New Stack(Of Integer)(10)

      TestPushDouble()
      TestPopDouble() 
      TestPushInteger()
      TestPopInteger() 
   End Sub 

   Sub TestPushDouble()
      Try
         Console.WriteLine("Pushing elements onto doubleStack")

         For Each element As Double In doubleElements
            Console.Write("{0:F1} ", element)
            doubleStack.Push(element)
         Next element
      Catch exception As GenericStackException
         Console.Error.WriteLine("Message: " & exception.Message)
         Console.Error.WriteLine(exception.StackTrace)
      End Try
   End Sub

   Sub TestPopDouble()
      Try
         Console.WriteLine("Popping elements from doubleStack")
         Dim popValue As Double

         While True
            popValue = doubleStack.Pop()
            Console.Write("{0:F1} ", popValue)
         End While
      Catch exception As GenericStackException
         Console.Error.WriteLine()
         Console.Error.WriteLine("Message: " & exception.Message)
         Console.Error.WriteLine(exception.StackTrace)
      End Try
   End Sub

   Sub TestPushInteger()
      Try
         Console.WriteLine("Pushing elements onto integerStack")
         For Each element As Integer In integerElements
            Console.Write("{0} ", element)
            integerStack.Push(element) ' push onto integerStack
         Next element
      Catch exception As GenericStackException
         Console.Error.WriteLine()
         Console.Error.WriteLine("Message: " & exception.Message)
         Console.Error.WriteLine(exception.StackTrace)
      End Try
   End Sub
   
   Sub TestPopInteger()
      Try
         Console.WriteLine("Popping elements from integerStack")
         Dim popValue As Integer

         While True
            popValue = integerStack.Pop()
            Console.Write("{0} ", popValue)
         End While
      Catch exception As GenericStackException
         Console.Error.WriteLine()
         Console.Error.WriteLine("Message: " & exception.Message)
         Console.Error.WriteLine(exception.StackTrace)
      End Try
   End Sub
End Module

Public Class Stack(Of E)
   Private top As Integer
   Private elements() As E

   Public Sub New()
      MyClass.New(10)
   End Sub ' New

   Public Sub New(ByVal stackSize As Integer)
      If stackSize > 0 Then 
         elements = New E(stackSize - 1) {}
      Else
         elements = New E(9) {}
      End If

      top = -1
   End Sub ' New

   Public Sub Push(ByVal pushValue As E)
      If top = elements.Length - 1 Then
         Throw New GenericStackException(String.Format("Stack is full, cannot push {0}", pushValue))
      End If

      top += 1
      elements(top) = pushValue 
   End Sub

   Public Function Pop() As E
      If top = -1 Then
         Throw New GenericStackException("Stack is empty, cannot pop")
      End If

      top -= 1
      Return elements(top + 1) 
   End Function 
End Class


Public Class GenericStackException : Inherits ApplicationException
   Public Sub New()
      MyBase.New("Stack is empty")
   End Sub ' New

   Public Sub New(ByVal exception As String)
      MyBase.New(exception)
   End Sub
End Class

Pushing elements onto doubleStack
1.1 2.2 3.3 4.4 5.5 6.6 Message: Stack is full, cannot push 6.6
   at Stack`1.Push(E pushValue)
   at StackTest.TestPushDouble()
Popping elements from doubleStack
5.5 4.4 3.3 2.2 1.1
Message: Stack is empty, cannot pop
   at Stack`1.Pop()
   at StackTest.TestPopDouble()
Pushing elements onto integerStack
1 2 3 4 5 6 7 8 9 10 11
Message: Stack is full, cannot push 11
   at Stack`1.Push(E pushValue)
   at StackTest.TestPushInteger()
Popping elements from integerStack
10 9 8 7 6 5 4 3 2 1
Message: Stack is empty, cannot pop
   at Stack`1.Pop()
   at StackTest.TestPopInteger()