Mask a Textbox

Private Function MaskText(txtTarget As VB.Textbox, strMask As String)
 Static bolRunning   As Boolean
 
 If bolRunning Then
 Exit Function
 End If
 
 bolRunning = True
 Dim strTarget_Text   As String
 strTarget_Text = txtTarget.Text
 
 Dim lngCursor_Pos   As Long
 lngCursor_Pos = txtTarget.SelStart
 
 If Len(strMask) > Len(strTarget_Text) Then
 strTarget_Text = strTarget_Text & Space(Len(strMask) - Len(strTarget_Text))
 ElseIf Len(strMask) < Len(strTarget_Text) Then
 strTarget_Text = Left(strTarget_Text, Len(strMask))
 ElseIf Len(strMask) = 0 Then
 Exit Function
 End If
 
 Dim strTarget_Char   As String * 1
 Dim strMask_Char   As String * 1
 
 Dim strTemp     As String
 Dim bolAlpha    As Boolean
 
 Dim aryLiterals    As Variant
 aryLiterals = Array("(", ")", "-", ".", ",", ":", ";", "/", "\", " ")
 
 Dim lngLiteral_Index  As Long
 Dim bolLiteral    As Boolean
 
 Dim lngChar_Index   As Long
 
 For lngChar_Index = 1 To Len(strMask)
 strTarget_Char = Mid(strTarget_Text, lngChar_Index, 1)
 strMask_Char = Mid(strMask, lngChar_Index, 1)
 
 For lngLiteral_Index = LBound(aryLiterals) To UBound(aryLiterals)
  bolLiteral = (strMask_Char = aryLiterals(lngLiteral_Index))
  
  If bolLiteral Then
  Exit For
  End If
 Next lngLiteral_Index
 
 Select Case strMask_Char
  Case "#":
  If (Not IsNumeric(strTarget_Char)) And (strTarget_Char <> " ") Then
   strTemp = Right(strTarget_Text, Len(strTarget_Text) - lngChar_Index)
   
   If lngChar_Index > 1 Then
   strTarget_Text = Left(strTarget_Text, lngChar_Index - 1)
   Else
   strTarget_Text = ""
   End If
   
   strTarget_Text = strTarget_Text & " " & strTemp
  End If
  Case "@":
  bolAlpha = ((Asc(strTarget_Char) >= 65) And (Asc(strTarget_Char) <= 90)) Or ((Asc(strTarget_Char) >= 97) And (Asc(strTarget_Char) <= 122))
  
  If (Not bolAlpha) And (strTarget_Char <> " ") Then
   strTemp = Right(strTarget_Text, Len(strTarget_Text) - lngChar_Index)
   
   If lngChar_Index > 1 Then
   strTarget_Text = Left(strTarget_Text, lngChar_Index - 1)
   Else
   strTarget_Text = ""
   End If
   
   strTarget_Text = strTarget_Text & " " & strTemp
  End If
  Case Else:
  If (strTarget_Char <> strMask_Char) And bolLiteral Then
   strTemp = Right(strTarget_Text, Len(strTarget_Text) - (lngChar_Index - 1))
   
   strTarget_Text = Left(strTarget_Text, lngChar_Index - 1)
   strTarget_Text = strTarget_Text & strMask_Char & strTemp
   
   If lngChar_Index = lngCursor_Pos Then
   lngCursor_Pos = lngCursor_Pos + 1
   End If
  End If
 End Select
 Next lngChar_Index
 
 txtTarget.Text = Left(strTarget_Text, Len(strMask))
 txtTarget.SelStart = lngCursor_Pos
 
 bolRunning = False
End Function