VBA - Stream very large (GBs) single line (no crlf, cr, lf) text / xml file and modify same file.

[KayTannee]

Hi,

I'm trying to stream through a text file and remove a whole tag from the XML.

"<" & "Tagname */><tagname *="">"

. (Ampersand just there as forum deletes the tag)
<tagname *=""><tagname *="">The issue is the text/xml files can be anywhere from a few KBs to multiple GBs. The file also has no vbcrlf, vbcr or vblf in them.

Sub FixXML(FileName As String, TagName as string)
Dim FSO As Object, TxtS As Object
Dim OrigFileContents As String, NewFileContents As String
Dim StrtID As Long
Dim FrontBit As String, EndBit As String


Set FSO = CreateObject("Scripting.FileSystemObject")
Set TxtS = FSO.OpenTextFile(FileName)
OrigFileContents = TxtS.ReadAll


StrtID = InStr(1, OrigFileContents, "<" & TagName & " ", vbTextCompare)

If StrtID > 0 Then
    FrontBit = Left(OrigFileContents, StrtID - 1)
    EndBit = Mid(OrigFileContents, InStr(StrtID, OrigFileContents, "/>") + 2)
    NewFileContents = FrontBit & EndBit


    If OrigFileContents <> NewFileContents Then
        Set TxtS = FSO.OpenTextFile(FileName)
        TxtS.write NewFileContents
        TxtS.Close
        tCounter = tCounter + 1
    End If
End If


End Sub

This works great using a FileSystemObject to just ReadAll, modify the string and then write the whole string back to the same file. However if the file gets large enough then I get an out of memory error trying to load the string.

The below is currently method I'm messing around with. For it to work though, I'd probably need to be able to
a) Stream through by character backwards.
b) Be able to modify/snipout specific characters

Set FSO = CreateObject("Scripting.FileSystemObject")
Set TxtS = FSO.OpenTextFile(FileName)
Do Until TxtS.AtEndOfStream
    OrigFileContents = TxtS.Read(10000)
    'Do some modifying, being careful if tag looking for is split over 2 blocks.
    'TxtS.write(10000) = OrigFileContents  'This obviously doesn't work :( .....
Loop

I'd ideally like to be able to just make the snip in the file quickly, modifying the original file. The only solution I can currently think of would be a slow and disk space intensive Read one file, and append to another... Creating 2 files then deleting and replacing the original. There surely must be an easier way?

I've tried using something like this, but its slow to load in, and I can't work out how to delete my tag nor modify the file.

    Set XDoc = CreateObject("MSXML2.DOMDocument")
    XDoc.async = False: XDoc.validateOnParse = False
    XDoc.Load ("C:\temp\xml.xml")

If anyone can give me any help it would be appreciated.</tagname></tagname></tagname>