Initial data commit

Task/Doubly-linked-list-Definition/Visual-Basic-.NET/doubly-linked-list-definition.vb

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+Public Class DoubleLinkList(Of T)
+   Private m_Head As Node(Of T)
+   Private m_Tail As Node(Of T)
+
+   Public Sub AddHead(ByVal value As T)
+       Dim node As New Node(Of T)(Me, value)
+
+       If m_Head Is Nothing Then
+           m_Head = Node
+           m_Tail = m_Head
+       Else
+           node.Next = m_Head
+           m_Head = node
+       End If
+
+   End Sub
+
+   Public Sub AddTail(ByVal value As T)
+       Dim node As New Node(Of T)(Me, value)
+
+       If m_Tail Is Nothing Then
+           m_Head = node
+           m_Tail = m_Head
+       Else
+           node.Previous = m_Tail
+           m_Tail = node
+       End If
+   End Sub
+
+   Public ReadOnly Property Head() As Node(Of T)
+       Get
+           Return m_Head
+       End Get
+   End Property
+
+   Public ReadOnly Property Tail() As Node(Of T)
+       Get
+           Return m_Tail
+       End Get
+   End Property
+
+   Public Sub RemoveTail()
+       If m_Tail Is Nothing Then Return
+
+       If m_Tail.Previous Is Nothing Then 'empty
+           m_Head = Nothing
+           m_Tail = Nothing
+       Else
+           m_Tail = m_Tail.Previous
+           m_Tail.Next = Nothing
+       End If
+   End Sub
+
+   Public Sub RemoveHead()
+       If m_Head Is Nothing Then Return
+
+       If m_Head.Next Is Nothing Then 'empty
+           m_Head = Nothing
+           m_Tail = Nothing
+       Else
+           m_Head = m_Head.Next
+           m_Head.Previous = Nothing
+       End If
+   End Sub
+
+End Class
+
+Public Class Node(Of T)
+   Private ReadOnly m_Value As T
+   Private m_Next As Node(Of T)
+   Private m_Previous As Node(Of T)
+   Private ReadOnly m_Parent As DoubleLinkList(Of T)
+
+   Public Sub New(ByVal parent As DoubleLinkList(Of T), ByVal value As T)
+       m_Parent = parent
+       m_Value = value
+   End Sub
+
+   Public Property [Next]() As Node(Of T)
+       Get
+           Return m_Next
+       End Get
+       Friend Set(ByVal value As Node(Of T))
+           m_Next = value
+       End Set
+   End Property
+
+   Public Property Previous() As Node(Of T)
+       Get
+           Return m_Previous
+       End Get
+       Friend Set(ByVal value As Node(Of T))
+           m_Previous = value
+       End Set
+   End Property
+
+   Public ReadOnly Property Value() As T
+       Get
+           Return m_Value
+       End Get
+   End Property
+
+   Public Sub InsertAfter(ByVal value As T)
+       If m_Next Is Nothing Then
+           m_Parent.AddTail(value)
+       ElseIf m_Previous Is Nothing Then
+           m_Parent.AddHead(value)
+       Else
+           Dim node As New Node(Of T)(m_Parent, value)
+           node.Previous = Me
+           node.Next = Me.Next
+           Me.Next.Previous = node
+           Me.Next = node
+       End If
+   End Sub
+
+   Public Sub Remove()
+       If m_Next Is Nothing Then
+           m_Parent.RemoveTail()
+       ElseIf m_Previous Is Nothing Then
+           m_Parent.RemoveHead()
+       Else
+           m_Previous.Next = Me.Next
+           m_Next.Previous = Me.Previous
+       End If
+   End Sub
+
+End Class