1 unstable release

Uses new Rust 2024

new 0.1.0+0.2 May 2, 2025

#553 in Procedural macros

Download history 100/week @ 2025-04-28

100 downloads per month

MIT/Apache

25KB
658 lines

Loess-Rust

loess-rust is a Loess-grammar that tracks Rust's stable grammar by closely following The Rust Reference.

Here's what to expect:

  • Shallow parsing (by default). For tokens with delimited groups, like Visibility, you can opt into deeper (or customised!) parsing via generics.

  • Public fields and one-time validation. The parser checks token specifics once when processing input, but trusts you otherwise.

  • Some bugs. For example, none-delimited groups aren't handled yet, which can cause issues when generating macro input with a macro_rules! macro.

Here's what not to expect:

  • Complete coverage of Rust's grammar. In fact, loess-rust really makes no attempt at all in this regard, since I only implement what I need. In particular, unstable grammar is generally out of scope. (Loess can help you supply it yourself!)

    Temporary opaque implementations of additional grammar tokens are available in the loess-rust-opaque crate.

  • Debug-implementations. They aren't that useful here in my experience, but they would increase compile-times.

  • Absence of major version bumps. Rust's grammar is a moving target and Loess's grammar tokens aren't marked #[non_exhaustive] for ease of use.

    However, shallow parsing should make upgrades fairly painless and errors should alert you specifically to grammar changes that are relevant to you.

    I should also be able to use the semver trick each time (reexport compatible new-major-version types in the older version) to keep incompatibilities and overall compile time to a minimum.

How to read the version number:

After the "+", the most-major version of the (most directly) compatible Loess releases is listed.

Dependencies

~180KB