Implement lazy glif parsing

[knutnergaard]

In need of a project to learn Rust and without knowing about norad, I created a glif parser with lazy and eager options a couple months back. It is available here, currently without support for multiple layers and several other deficiencies.

Since there seems to be little interest in my project, I was wondering whether norad is still being maintained, and whether there is any interest here in adopting some of the code of ufo-gleaner.

I haven't done any thorough profiling, but ufo-gleaner seems to provide a substantial efficiency boost for individual GLIF files, and at least a minor one for the entire GLIF set.

[madig]

Norad is in still in use, yes. I thought about lazy loading a while back, but eager loading was really fast already. It could be interesting to selectively write glif files for UFOs like ufolib does, instead of erasing everything and writing the whole UFO in one go.

[knutnergaard]

ufo-gleaner is not quite as lazy as ufoLib, since the speed of Rust deems it unnecessary. It parses each glif file eagerly, but doesn't load the data until needed, utilizing dynamic borrowing and reference-counting pointers for maximum efficiency. It also handles ufoz through virtual filesystem adaptation.

I've been working on the validation and some other improvements which I'll push in the coming days. Please have a look, and let me know if the code might be of use.

[rsheeter]

It would be interesting to know more about the efficiency boost, what did you compare and what are the metrics?

For context, it might be most natural in norad to extend https://docs.rs/norad/latest/norad/struct.DataRequest.html to support loading a subset of glifs.