some messy... but useful code

I have just created this VB ASP.NET code for handling HTML source code..
It will retrieve HTML elements and attributes of those elements from a remote (or local) webpage.
It gets a little bit messy but it should work most of the time (if the HTML is poorly coded it might play up).
I have coded an example in the page_load to demonstrate it's uses.

Well here is the code:
first:
Imports System.Net
Imports System.IO

   Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        'an example of how to use the code:
        'outputs actual links, anchor texts and the HREF attribrute from all links on www.google.com

        Dim i As Integer = 0
        Dim google As HTMLDoc
        Dim alink As HTMLElement

        google.Source = GetWebPage("http://www.google.com")
        alink = google.getElementByTagName("a")

        For i = 0 To alink.count - 1
            Response.Write("Actual Link: " & alink.Item(i).outerHTML & "<br>")
            Response.Write("Anchor Text: " & alink.Item(i).innerHTML & "<br>")
            Response.Write("HREF: " & alink.Item(i).getAttributeValue("href") & "<br><br>")
        Next

    End Sub

    Function GetWebPage(ByVal strURI As String) As String
        Dim r As WebResponse
        r = WebRequest.Create(New Uri(strURI)).GetResponse()
        Dim sr As New StreamReader(r.GetResponseStream())
        Do Until sr.EndOfStream
            GetWebPage = sr.ReadToEnd
        Loop
        r.Close()
        sr.Close()
    End Function


    Structure HTMLDoc
        Dim Source As String
        Function getElementByTagName(ByVal tagname As String) As HTMLElement
            Dim p1, p2, p3, p4, p5 As Integer
            Dim c As Integer
            c = 0
            p1 = 0
            tagname = LCase(tagname)

            With getElementByTagName
                Do
                    p1 = InStr(p1 + 1, LCase(Source), "<" & tagname)
                    If p1 = 0 Then Exit Do
                    p2 = InStr(p1, Source, ">")
                    ReDim Preserve .Item(c)
                    If Mid(Source, p2 - 1, 1) = "/" Then
                        .Item(c).innerHTML = ""
                        .Item(c).outerHTML = Mid(Source, p1, (p2 + 1) - p1)
                    Else
                        p3 = InStr(p2, LCase(Source), "</" & tagname)
                        p4 = p3 + Len(tagname) + 3
                        .Item(c).innerHTML = Mid(Source, p2 + 1, p3 - (p2 + 1))
                        .Item(c).outerHTML = Mid(Source, p1, p4 - p1)
                    End If
                    c = c + 1
                Loop Until p1 = 0 Or p2 = 0
                .count = c
            End With
        End Function
    End Structure

    Structure HTMLElement
        Dim count As Integer
        Dim Item() As HTMLElementItem
    End Structure

    Structure HTMLElementItem
        Dim outerHTML As String
        Dim innerHTML As String
        Function getAttributeValue(ByVal attr As String) As String
            Dim p1, p2, p3 As Integer
            Dim i As Integer = 0
            Dim formats(2) As String
            Dim endchars(3) As String
            attr = LCase(attr)

            formats(0) = attr & "=" & Chr(34)
            formats(1) = attr & "='"
            formats(2) = attr & "="
            endchars(0) = Chr(34)
            endchars(1) = "'"
            endchars(2) = Chr(32)
            endchars(3) = ">"
            For i = 0 To 2
                p1 = InStr(LCase(outerHTML), formats(i))
                If p1 > 0 Then
                    p2 = InStr(p1 + Len(formats(i)), outerHTML, endchars(i))
                    If i = 2 Then
                        p3 = InStr(p1 + Len(formats(i)), outerHTML, endchars(3))
                        If p3 < p2 And p3 > 0 Or p2 = 0 And p3 > 0 Then
                            p2 = p3
                        End If
                    End If
                    If p2 > 0 Then
                        getAttributeValue = Mid(outerHTML, p1 + Len(formats(i)), p2 - (p1 + Len(formats(i))))
                        Exit For
                    End If
                End If
            Next
        End Function
    End Structure

Code (markup):

I know it's ugly but it seems to work alright so far and I have been looking for something like this for a while and couldn't find it. So hopefully it is useful to someone else also.

 

Nice thing to try and play with. looks helpful. thanx.
It is simple enough for a conversion to C# to work
Such as: http://www.developerfusion.com/tools/convert/vb-to-csharp/ and http://www.dotnetspider.com/convert/Vb-To-Csharp.aspx

 

ugly, but necessarily so. Nice code, thanks.

 

Yeah i've implemented it and ended up just writing seperate functions most of the time for different tags. It's a little bit buggy... but the idea is there (work's great for <a> tags though)