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''' <summary>
''' Compares the properties of two generic objects.
''' </summary>
''' <remarks></remarks>
Public Class PropertyComparer
    Implements IComparer

    Private mSortDescriptions As New List(Of PropertySortDescription)
    ''' <summary>
    ''' The sort descriptions for comparing in ordination to this list. If a property is equal with both objects, the next property description in list will be used for comparing until one object differs to the other.
    ''' </summary>
    ''' <value></value>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Public ReadOnly Property SortDescriptions() As List(Of PropertySortDescription)
        Get
            Return mSortDescriptions
        End Get
    End Property
    ''' <summary>
    ''' Compares both objects.
    ''' </summary>
    ''' <param name="x">First Object</param>
    ''' <param name="y">Second Object</param>
    ''' <returns></returns>
    ''' <remarks></remarks>
    
    Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements System.Collections.IComparer.Compare
        If (x IsNot Nothing And y IsNot Nothing) Then
            For Each desc In mSortDescriptions
                Dim xValue As Object = desc.Descriptor.GetValue(x)
                Dim yValue As Object = desc.Descriptor.GetValue(y)
                Dim res As Integer = desc.Direction * desc.Comparer.Compare(xValue, yValue)
                If res <> 0 Then Return res
            Next
            Return 0
        Else
            Return 0
        End If
    End Function
End Class

''' <summary>
''' Provides properties for storing reflection information of a generic object.
''' </summary>
''' <remarks></remarks>
Public Class PropertySortDescription
    Implements INotifyPropertyChanged
    Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged

    Private mDescriptor As PropertyDescriptor
    Private mDirection As ListSortDirection = ListSortDirection.Ascending
    Private mComparer As System.Collections.IComparer
    Friend ReadOnly Property Comparer() As System.Collections.IComparer
        Get
            Return mComparer
        End Get
    End Property
    Public ReadOnly Property Descriptor() As PropertyDescriptor
        Get
            Return mDescriptor
        End Get
    End Property
    Public Property Direction() As ListSortDirection
        Get
            Return mDirection
        End Get
        Set(ByVal value As ListSortDirection)
            mDirection = value
        End Set
    End Property

    Public Sub New(ByVal pd As PropertyDescriptor, ByVal dir As ListSortDirection)
        Me.New(pd)
        mDirection = dir
    End Sub
    Public Sub New(ByVal pd As PropertyDescriptor)
        Me.SetDescriptor(pd)
    End Sub

    Public Sub New(ByVal prpName As String, ByVal t As Type, ByVal dir As ListSortDirection)
        Me.New(prpName, t)
        mDirection = dir
    End Sub
    Public Sub New(ByVal prpName As String, ByVal t As Type)
        Dim prps As PropertyDescriptorCollection = TypeDescriptor.GetProperties(t)
        For Each prp As PropertyDescriptor In prps
            If prp.Name = prpName Then
                Me.SetDescriptor(prp)
                prps = Nothing
                Exit For
            End If
        Next
        If mDescriptor Is Nothing Then Throw New ArgumentException("A property with the passed name couldn't be found on passed object.", "prpName")
    End Sub

    Private Sub SetDescriptor(ByVal pd As PropertyDescriptor)
        If pd Is Nothing Then : Throw New ArgumentNullException("pd", "Property descriptor is not allowed to be null/Nothing.")
        Else
            Try
                mDescriptor = pd

                mComparer = DirectCast(GetType(Comparer).MakeGenericType(mDescriptor.PropertyType).InvokeMember("Default", Reflection.BindingFlags.GetProperty Or Reflection.BindingFlags.[Public] Or Reflection.BindingFlags.[Static], Nothing, Nothing, Nothing), System.Collections.IComparer)
            Catch ex As Exception
                Debug.WriteLine(ex.Message)
            End Try
        End If
    End Sub



End Class