orbits is a general purpose layeredfs crate that supports three layers: physical, patch, and virtual.
Alternatively, the physical layer could also be referred to as the archive layer, as its intent is to be used as the last resort when loading a file, the Default of the file loader, if you will.
The patch layer is intended to be where you can scan roots on disc. Using orbits's Tree under the hood, it will generate a file tree which allows easy traversal via walk_paths and will automatically detect (and reject) conflicts depending on how it's configured.
The virtual layer is mostly for those who want to implement on-the-fly data generation or file loading callbacks.
Well, nothing is. The whole point of orbits is that you can use it to generate your own layered filesystem application, and ultimately it's up to you to decide what the best way to go about doing that is.
For my uses, orbits having a dedicated virtual layer will make for extremely easy API callbacks and the like. The patch section is helpful for automatically rejecting file conflicts, and the physical layer is for the archive. But really, you can organize it whatever way you want, this is just how I suggest :)
The FileLoader trait allows for the implementer to design their own object/loader for any of the three sections. It only requires a few functions, and orbits also provides a orbits::StandardLoader right out of the box which uses std::fs.
The whole point of a layered filesystem is that a bunch of different roots can all come together and function as one cohesive file tree. However, what if something is conflicting?
Fear not! For orbits offers a variety of different conflict handlers for managing conflicts.
The strict conflict handler will cause orbits to panic on a conflict. This is currently planned to be replaced with returning an Error for better error handling.
The NoRoot conflict handler will cause orbits to reject every single file from the root of a conflicting file.
The First conflict handler will cause orbits to keep the first file that matches the local path in the file tree, while Last will replace it.