ASK HN: Some thoughts on a possible AST-aware org-mode three way merge driver

6 points by cidra_ 1y ago ↗ HN

One thing I'm always craving for is a way to seamlessly sync my Org documents between my laptop, my smartphone and my tablet. Using git (along with some utilities like git-sync[0]) is decent, but when it comes to capturing a lot or heavily operating on a large agenda file, it's easy to incur in some conflicts that need manual intervention which kind of take away the smoothness from my plannings.

I've noticed that many people do use git for syncing their notes and treat manual conflict handling simply as part of life. For some reasons I just can't bring myself to like it, but I also really would like to have full syncing capabilities on Org mode.

I've seen that in 2012 some folks implemented a dedicated merge driver (org-merge-driver[1]) which only covers the basics but is aware of org syntax and operated on a per-headline basis, merging tags if needed and identifying changes from the name/id of the headline.

I've been wondering if something like this could be re-implemented using org-mode's own parser (org-element). I've been reading a paper that describes a three way merge for XML documents (and generic hierarchical documents) without IDs being involved[2] and another paper that describes a way to merge ordered sequences that takes movements (even crossing ones), deletions and insertions into account[3]. Nothing bleeding edge and I wonder if something like this may stand on its own feet from a functional and performance perspective.

Do you think something like this may be a good idea? Do you have some advice to give on this regard? Sorry for the quite abstract and quite fluff-y post, but this idea has been hanging in my head for too long.

[0] https://github.com/simonthum/git-sync

[1] https://orgmode.org/worg/org-contrib/gsoc2012/student-projects/git-merge-tool/manual.html

[2] A three-way merge for XML documents :: https://dl.acm.org/doi/10.1145/1030397.1030399

[3] A graph-based algorithm for three-way merging of ordered collections in EMF models :: https://www.sciencedirect.com/science/article/pii/S0167642315000532

5 comments

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sargstuff 1y ago ↗

Although designed as code editor, Zed certainly could be used/wrangled to handle things as outlined.

[0] zed : http://news.ycombinator.com/item?id=39119835

difftastic : https://difftastic.wilfred.me.uk/

tra3 1y ago ↗

I've been using dropbox to sync my org docs and has worked remarkably well.

I once tried using synching and that resulted in almost immediate conflicts. This is not my area of expertise, but if I had to guess it's because dropbox is master-slave, where's synching is peer to peer.

The mobile story for org-mode is still not great.

cidra_ 1y ago ↗

If you have a 3rd always on device on Syncthing i believe the outcome would be similiar to Dropbox, right?

Conflicts are unavoidable if two hosts write in an interleaved manner and with unreliable internet connection. For example

Shopping List

- Eggs

- Bread

- Molk <---- Host 1 edits this into "Milk"

- Sugar

- Coffee <---- Host 2 adds this line

If these 2 changes occur at the same time, how would Dropbox merge them, having no knowledge of the semantics of the org document? There is a conflict and Dropbox may solve it in a "last writer wins" manner or by performing a merge by line like in git.

I believe you're right, the key issue being out of order writes. With dropbox mostly being always online that has (almost?) never happened to me though.