VB.NET Tuple<T1,T2,T3,T4,T5,T6,T7,TRest>.IStructuralComparable.CompareTo方法代碼示例

' 導入命名空間
Imports System.Collections
Imports System.Collections.Generic

Public Class PopulationComparer(Of T1, T2, T3, T4, T5, T6, T7, T8) : Implements IComparer
   Private itemPosition As Integer
   Private multiplier As Integer = -1
      
   Public Sub New(component As Integer)
      Me.New(component, True)
   End Sub
   
   Public Sub New(component As Integer, descending As Boolean)
      If Not descending Then multiplier = 1
      
      If component <= 0 Or component > 8 Then 
         Throw New ArgumentException("The component argument is out of range.")
      End If
      itemPosition = component
   End Sub 
   
   Public Function Compare(x As Object, y As Object) As Integer _
                   Implements IComparer.Compare
 
      Dim tX As Tuple(Of T1, T2, T3, T4, T5, T6, T7, Tuple(Of T8)) = TryCast(x, Tuple(Of T1, T2, T3, T4, T5, T6, T7, Tuple(Of T8)))
      If tX Is Nothing Then
         Return 0
      Else
         Dim tY As Tuple(Of T1, T2, T3, T4, T5, T6, T7, Tuple(Of T8)) = DirectCast(y, Tuple(Of T1, T2, T3, T4, T5, T6, T7, Tuple(Of T8)))
         Select Case itemPosition
            Case 1
               Return Comparer(Of T1).Default.Compare(tX.Item1, tY.Item1) * multiplier
            Case 2
               Return Comparer(Of T2).Default.Compare(tX.Item2, tY.Item2) * multiplier
            Case 3
               Return Comparer(Of T3).Default.Compare(tX.Item3, tY.Item3) * multiplier
            Case 4
               Return Comparer(Of T4).Default.Compare(tX.Item4, tY.Item4) * multiplier
            Case 5
               Return Comparer(Of T5).Default.Compare(tX.Item5, tY.Item5) * multiplier
            Case 6
               Return Comparer(Of T6).Default.Compare(tX.Item6, tY.Item6) * multiplier
            Case 7
               Return Comparer(Of T7).Default.Compare(tX.Item7, tY.Item7) * multiplier
            Case 8
               Return Comparer(Of T8).Default.Compare(tX.Rest.Item1, tY.Rest.Item1) * multiplier
         End Select      
      End If
   End Function
End Class

Module Example
   Public Sub Main()
      ' Create array of octuples with population data for three U.S. 
      ' cities, 1940-2000.
      Dim cities()  = _
          { Tuple.Create("Los Angeles", 1504277, 1970358, 2479015, 2816061, 2966850, 3485398, 3694820),
            Tuple.Create("New York", 7454995, 7891957, 7781984, 7894862, 7071639, 7322564, 8008278),  
            Tuple.Create("Chicago", 3396808, 3620962, 3550904, 3366957, 3005072, 2783726, 2896016),  
            Tuple.Create("Detroit", 1623452, 1849568, 1670144, 1511462, 1203339, 1027974, 951270) }
      ' Display array in unsorted order.
      Console.WriteLine("In unsorted order:")
      For Each city In cities
         Console.WriteLine(city.ToString())
      Next
      Console.WriteLine()
      
      Array.Sort(cities, New PopulationComparer(Of String, Integer, Integer, Integer, Integer, Integer, Integer, Integer)(2)) 
                           
      ' Display array in sorted order.
      Console.WriteLine("Sorted by population in 1950:")
      For Each city In cities
         Console.WriteLine(city.ToString())
      Next
      Console.WriteLine()
      
      Array.Sort(cities, New PopulationComparer(Of String, Integer, Integer, Integer, Integer, Integer, Integer, Integer)(8))
                           
      ' Display array in sorted order.
      Console.WriteLine("Sorted by population in 2000:")
      For Each city In cities
         Console.WriteLine(city.ToString())
      Next
   End Sub
End Module