C++ Immutable Projects

immer

25 2,420 6.7 C++

Postmodern immutable and persistent data structures for C++ — value semantics at scale (by arximboldi)

Project mention: Text Editor Data Structures: Rethinking Undo | news.ycombinator.com | 2023-12-11

I've been working on an editor (not text) in C++ and pretty early got into undo/redo. I went down the route of doIt/undoIt for commands but that quickly got old. There was both the extra work needed to implement undo separately for every operation, but also the nagging feeling that the undo operation for some operation wasn't implemented correctly.
In the end, I switched to representing the entire document state using persistent data structures (using the immer library). This vastly simplified things and implementing undo/redo becomes absolutely trivial when using persistent data structures. It's probably not something that is suitable for all domains, but worth checking out.
https://github.com/arximboldi/immer

ewig

3 517 0.0 C++

The eternal text editor — Didactic Ersatz Emacs to show immutable data-structures and the single-atom architecture

Project mention: Text Editor Data Structures | news.ycombinator.com | 2023-06-13

You might be interested in ewig and immer by Juan Pedro Bolivar Puente:
https://github.com/arximboldi/ewig
https://github.com/arximboldi/immer
See the author instantly opening a ~1GB text file with async loading, paging through, copying/pasting, and undoing/redoing in their prototype “ewig” text editor about 27 minutes into their talk here:
https://m.youtube.com/watch?v=sPhpelUfu8Q
It’s backed by a “vector of vectors” data structure called a relaxed radix balanced tree:
https://infoscience.epfl.ch/record/169879/files/RMTrees.pdf
That original paper has seen lots of attention and attempts at performance improvements, such as:
https://hypirion.com/musings/thesis
https://github.com/hyPiRion/c-rrb

WorkOS

workos.com sponsored

The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.

NOTE: The open source projects on this list are ordered by number of github stars. The number of mentions indicates repo mentiontions in the last 12 Months or since we started tracking (Dec 2020).