A Delta algorithm ported to Rust

Work In Progress !!!

This algorithm is used in fossil and there it has been implemented in C-99. I needed it in my Rust projects and here is reimplementation in Rust.

Once it is ported it will expose two public functions: - delta: fn(a:&str, b:&str) -> String - deltainv: fn(a:&str, d:&str) -> String

// creating delta between a and its next version b
let d = delta(a, b);

// applying delta to b to get previous version a
let s = deltainv(b, d);

assert_eq!(s, a);

Therefore if you have some text value a, and user changes that text to value b, using delta function you can get a compressed delta value d that you can store and keep it along with the new text value b. If later user wants to see the previous version of text, you can use deltainv(b, d) to get the previous value. If you keep all consequtive deltas you can use deltainv multiple times to get any of the earlier text versions.

The Delta value calculated between two utf-8 encoded strings is itself utf-8 encoded string.

The algorithm is described very well here in the fossil wiki.

The code of this repository is best viewed in Leo editor. The outline containing the code is in a single outline file: fossil-delta-ref.leo.