问题描述
我有一个通用类，它将根据指定的任何属性对数据对象进行排序。它按 Ascii 或字母数字排序，升序或降序。基于也在别处的代码 here。 我想做的是简化这个调用。我必须使用
Data.sort(New PropertyComparer(Of Plane)("TailNumber",PropertyComparer(Of Plane).sortDirectionType.Ascending,PropertyComparer(Of Plane).sortTypeType.AlphaNumeric))
有没有办法减少传入的SortDirectionType和SortTypeType参数的长度？
Sub TestPropertySort()
Dim Data = GetData()
Data.sort(New PropertyComparer(Of Plane)("TailNumber",PropertyComparer(Of Plane).sortTypeType.AlphaNumeric))
print(Data,"Plane sort")
End Sub
Private Function GetData() As List(Of Plane)
Dim Planes As New List(Of Plane)
Planes.Add(New Plane("81192","Shenyang J-8II"))
Planes.Add(New Plane("30+91","Eurofighter typhoon"))
Planes.Add(New Plane("084","General Dynamics F-16 fighting Falcon"))
Planes.Add(New Plane("83","Test3"))
Planes.Add(New Plane("A16-97","Lockheed Hudson"))
Planes.Add(New Plane("L9162","Avro Anson"))
Planes.Add(New Plane("CH-06","Lockheed C-130 Hercules"))
Planes.Add(New Plane("CC-06","Test 2"))
Planes.Add(New Plane("967","Test 1"))
Planes.Add(New Plane("966","CASA C-212 Aviocar 300DF"))
Return Planes
End Function
Public Class PropertyComparer(Of T)
Implements IComparer(Of T)
Public Enum SortDirectionType
Descending = -1
Ascending = 1
End Enum
Public Enum SortTypeType
Ascii
AlphaNumeric
End Enum
Private SortPropertyName As String = ""
Private SortDirection As SortDirectionType
Private SortType As SortTypeType
Public Sub New(ByVal PropertyName As String)
SortPropertyName = PropertyName
SortDirection = SortDirectionType.Ascending
Me.sortType = SortTypeType.Ascii
End Sub
Public Sub New(ByVal PropertyName As String,ByVal Direction As SortDirectionType)
SortPropertyName = PropertyName
SortDirection = Direction
Me.sortType = SortTypeType.Ascii
End Sub
Public Sub New(ByVal PropertyName As String,ByVal Direction As SortDirectionType,ByVal SortType As SortTypeType)
SortPropertyName = PropertyName
SortDirection = Direction
Me.sortType = SortType
End Sub
Public Function Compare(ByVal x As T,ByVal y As T) As Integer Implements System.Collections.Generic.
IComparer(Of T).Compare
'The first thing Compare does is get the PropertyInfo record for the x and y arguments
Dim PropertyX As PropertyInfo = x.GetType().GetProperty(SortPropertyName)
If PropertyX Is nothing Then Throw New Exception("Sorting on property '" & SortPropertyName & "' bt that property does not exist in the class")
Dim PropertyY As PropertyInfo = y.GetType().GetProperty(SortPropertyName)
If PropertyX Is nothing Then Throw New Exception("Sorting on property '" & SortPropertyName & "' bt that property does not exist in the class")
'Obtain the value of the property using the argument's x and y and the PropertyInfo record
Dim px As Object = PropertyX.GetValue(x,nothing)
Dim py As Object = PropertyY.GetValue(y,nothing)
If SortType = SortTypeType.AlphaNumeric Then
Return CompareAlphaNumeric(Of String)(CType(px,String),CType(py,String)) * SortDirection
Else
'Inspects the type of the property to determine how to call the Compare method implemented at the end of the class.
'The Compare method implemented has a where predicate that limits the types of the parameter K to those that implement IComparable.
'The reason for this Is that IComparable types implement Compareto.
If (TypeOf px Is Integer) Then Return Compare(Of Integer)(CType(px,Integer),Integer)) * SortDirection
If (TypeOf px Is Decimal) Then Return Compare(Of Decimal)(CType(px,Decimal),Decimal)) * SortDirection
If (TypeOf px Is Date) Then Return Compare(Of Date)(CType(px,Date),Date)) * SortDirection
If (TypeOf px Is Double) Then Return Compare(Of Double)(CType(px,Double),Double)) * SortDirection
If (TypeOf px Is String) Then Return Compare(Of String)(CType(px,String)) * SortDirection
End If
Dim methodX As MethodInfo = PropertyX.GetType().getmethod("Compareto")
If (methodX Is nothing = False) Then
Return CType(methodX.Invoke(px,New Object() {py}),Integer) * SortDirection
Else
Return 0
End If
End Function
Private Function Compare(Of K As IComparable)(ByVal x As K,ByVal y As K) As Integer
Return x.Compareto(y)
End Function
Public Function CompareAlphaNumeric(Of K As IComparable)(ByVal X As String,ByVal Y As String) As Integer
'Validate the arguments.
If X = nothing Then Return 0
If Y = nothing Then Return 0
Dim LengthX As Integer = X.Length
Dim LengthY As Integer = Y.Length
Dim Marker1 As Integer = 0
Dim Marker2 As Integer = 0
'Loop over both Strings.
While Marker1 < LengthX And Marker2 < LengthY
Dim Char1 As Char = X(Marker1)
Dim Char2 As Char = Y(Marker2)
Dim TempX(LengthX) As Char
Dim IndexX As Integer = 0
Dim TempY(LengthY) As Char
Dim IndexY As Integer = 0
'Collect digits for String one.
Do
TempX(IndexX) = Char1
IndexX += 1
Marker1 += 1
If Marker1 < LengthX Then
Char1 = X(Marker1)
Else
Exit Do
End If
Loop While Char.IsDigit(Char1) = Char.IsDigit(TempX(0))
'Collect digits for String two.
Do
TempY(IndexY) = Char2
IndexY += 1
Marker2 += 1
If Marker2 < LengthY Then
Char2 = Y(Marker2)
Else
Exit Do
End If
Loop While Char.IsDigit(Char2) = Char.IsDigit(TempY(0))
'Convert to Strings.
Dim StrX = New String(TempX)
Dim StrY = New String(TempY)
'Parse Strings into Integers.
Dim Result As Integer
If Char.IsDigit(TempX(0)) And Char.IsDigit(TempY(0)) Then
Dim ThisNumericChunk = Integer.Parse(StrX)
Dim ThatNumericChunk = Integer.Parse(StrY)
Result = ThisNumericChunk.Compareto(ThatNumericChunk)
Else
Result = StrX.Compareto(StrY)
End If
'Return result if not equal.
If Not Result = 0 Then
Return Result
End If
End While
'Compare lengths.
Return LengthX - LengthY
End Function
End Class
解决方法
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