Peer Graph - Search Criteria Helper

Imports System.Text

Interface IASTNode
    Sub WriteToXML(ByVal xw As System.Xml.XmlTextWriter)
End Interface

Class SearchItem
    Implements IASTNode

    Friend Operation As String 'and/or/blank
    Friend Compare As Comparison

    Public Sub New(ByVal Comparison As Comparison, Optional ByVal Op As String = "")
        Compare = Comparison
        Operation = Op.ToLower
    End Sub

    Public Sub WriteToXML(ByVal xw As System.Xml.XmlTextWriter) Implements IASTNode.WriteToXML
        Compare.WriteToXML(xw)
    End Sub
End Class

Class SearchList
    Implements IASTNode

    Friend List As New ArrayList '(Of SearchItem)
    Public Sub New(ByVal item As SearchItem)
        List.Add(item)
    End Sub
    Public Sub Add(ByVal item As SearchItem)
        List.Add(item)
    End Sub

    Public Sub WriteToXML(ByVal xw As System.Xml.XmlTextWriter) Implements IASTNode.WriteToXML
        Dim item As SearchItem = CType(List(0), SearchItem)
        If List.Count = 1 Then
            item.WriteToXML(xw)
        Else
            ' operation is always the second item in the list
            Dim Operation As String = CType(List(1), SearchItem).Operation
            xw.WriteStartElement(Operation)

            Dim i As Integer = 0
            Do
                item.WriteToXML(xw)
                i += 1
                item = CType(List(i), SearchItem)
            Loop While i < List.Count - 1

            ' don't forget the last item
            item.WriteToXML(xw)
            xw.WriteEndElement()
        End If
    End Sub
End Class