getting zero length range from end of buffer

edit

Why not return the range that was passed in and set position = nil or -1 to indicate no more buffer to process?

Something like so?

function getString(buffer, position)
    local length = buffer:range(position, 4):uint()
    position = position + 4

    if length > 0 then
        local string = buffer:range(position, length)
        position = position + length
        return position, string
    end

    return position, nil

end

Thanks for responding Chuckc and cmaynard.

Yes, I can do that. But, as I said, it's not very convenient. I'd like to be able to do:

pos = 0
pos, str = getString(buffer, pos)
subtree:add(pf_from, str)
pos, str = getString(buffer, pos)
subtree:add(pf_to, str)
...

But, if I need to check for str being nil every time, it's not as simple.

Now that I think about it, is this really a Lua bug? Should I not be able to get a zero length TvbRange from the end of a Tvb. In other words, perhaps buffer:range(buffer:len(), 0) should not generate an error.

Thanks again, Graham.

My current workaround is:

function getString(buffer, position)
    local length = buffer:range(position, 4):uint()
    position = position + 4

    -- this is a workaround for a "Range is out of bounds" error with a zero length string at the very end of the buffer
    -- it should be just: local string = buffer:range(position, length)
    local pos = position
    if length == 0 and pos == buffer:len() then
        pos = pos - 1
    end
    local string = buffer:range(pos, length)

    local string = buffer:range(position, length)
    position = position + length
    return position, string
end

It's not correct, but it's close enough.