Re: Is there a package which uses markers to guess how to remap line numbers?

[rocky <rocky@gnu.org>]

On Nov 19, 10:39 am, Scott Frazer <frazer.sc...@gmail.com> wrote:
> rocky wrote:
> > I am writing a package (an interface to debuggers) that sets markers
> > on various lines (e.g. the lines at which the debugger stops at). Over
> > time, the buffer (source code) can change and the markers move around
> > with that. This is good.
>
> > Is there however a package which will suggest after buffer
> > modification how a particular line number might have changed given the
> > existingmarkerinformation and associated line number information for
> > that buffer?
>
> > Here is a concrete example. Let's say I have a buffer with amarkerat
> > lines 1, 5, 10 and 20. Let's say themarkerfor 10 moves to line 11
> > after modification but not the one for 1, 5 or 20.
>
> > If I ask about lines in the range 2-4, I may warn that overall the
> > buffer has changed but possibly not the one in that range. Of course
> > if I ask about lines 1, 5, or 20, I can warn that although the buffer
> > has changed, (parts of) those lines haven't. If I ask about a line in
> > the range 6-19 I can suggest there may be a move ahead a line with
> > more certainty of line 10.
>
> > Has anyone thought about this problem. Does such a package exist or
> > has anything like this been done as part of an existing package?
>
> What I have done for something similar is when the buffer is saved (or
> modified or whatever in your case) that I simply blow away all
> information that I am keeping about line numbers in this buffer and
> repopulate it by iterating over the markers (overlays in my case) and
> putting in the new line numbers.
>
> Scott

Thanks for your thoughts.

I think this situation is a little bit different in this regard: there
is an external program (e.g. a debugger) that has its notion the line/
position structure of the source; that is immutable (generally) over
the course of execution. So the problem is not that I want to store or
retrieve an up-to-date line number with a marker, I can easily get
using (line-number-at-pos) using the marker. Rather, I want map the
original line numbers that say a debugger reports interactively to the
corresponding line number in a modified file.

As I posted previously, rather than try to interpolate what the
original line numbers were, perhaps I need put a mark on every line or
on the possible stoppable lines. I am not sure though I would ever
want to update the original line number information since (generally)
the external program isn't going to change its line number
information.