Codama Rust Libraries

This project is still a work in progress but here's a super rough overview of what each crate does:

• codama-errors: Defines the Result/Error items for all crates.
• codama-nodes: Implements the Codama IDL in Rust.
• codama-syn-helpers: Helpers that boost syn items by using traits.
• codama-stores: A small tree structure that parses crates and files inside crates (recursively) and "owns" the syn::File for each traversed file.
• codama-koroks: A higher-level tree structure that represents things in your Rust code (modules, structs, enums, variants, types, etc.) You can think of it like a specialized syn tree. We call a "thing in your Rust code", a Korok (Japanese tree spirits). Each korok keeps track of a Option<Node> which is the currently resolved node for this piece of Rust code. Note that the korok tree uses syn references from stores mentioned above. So first you get a store that owns all the syn files, then you get a Korok tree that's essentially a parsed "view" of your stores.
• codama-korok-visitors: Each Korok can be visited by Korok visitors. This allows you to traverse the entire Rust code and adjust the Option<Node> as you wish. There is a RootKorok that is the entry point of the tree. Whichever node is associated with this RootKorok will become the RootNode of the Codama IDL. Therefore, you have visitors like CombineTypesVisitor and CombineModulesVisitor that go up the tree and combine nodes together until we reach the RootKorok.
• codama-korok-plugins: A plugin is trait (KorokPlugin) that defines a run function that accepts a mutable Korok and a next function to run the next plugin on the list. This means any visitor you call on the Korok before the next function will be executed before the other plugins, anything after the next function will override the other plugins (kinda like a middleware pipeline). There is a DefaultPlugin that calls a default visitor. This visitor does things like, setting base types, link nodes, program metadata, applying Codama macros and combining everything up the tree so the RootNode is set on the RootKorok. This is the first plugin on the list so you can run anything before or after it based on where you call the next function on your plugin. Note that most visitors in the default plugins won't override any existing Option<Node> in a Korok, so it's mostly there to fill as many gaps as possible. Also note that all visitors are composable so you can always re-use a visitor used in the default plugin for your own plugin — e.g. the MapVisitor to pass a function that applies on all koroks.
• codama-attributes: Parses Codama-specific attributes into structured items so they can then be used by visitors and codama-macros.
• codama-macros: A super small procedural macro crate that registers the Codama-specific attributes mentioned above.
• codama: The final library that re-exports most of the ones above and provide a super high level API for parsing IDL from paths to your Rust code.

Check out this example project to see how to use Codama macros in your Rust code using a build.rs script.