ron-lsp

Type validation for .ron files (in or out of the ide)

An LSP for RON files that provides autocomplete, diagnostics, go to definition, code actions, and hover support based on Rust type annotations. It can also be used to check in bulk via CLI, optionally with a path. ron-lsp check [<path>]

Getting started

Install:

cargo install ron-lsp

Add comment annotations to the top of .ron files like /* @[crate::models::User] */.

And then use the cli (from a rust project working directory):

ron-lsp check

It'll output something like this if there are warnings / errors:

You can optionally pass a file or folder. (e.g. ron-lsp check crates/sub-crate - it will recursively check all .ron files from that point.)

It will use the nearest Cargo.toml starting from the resolved .ron file.

Usage

Type Annotation Format

At the top of your RON file, add a block comment with the type annotation:

/* @[crate::models::User] */

User(
    id: 1,
    name: "Alice",
    email: "alice@example.com",
    age: 30,
)

The LSP will:

1. Parse the @[crate::models::User] annotation
2. Find the User struct in your Rust project
3. Extract field names, types, and documentation
4. Provide autocomplete and validation
5. Support Default trait for optional field omission
6. Provide code actions for inserting either required or missing fields, when applicable

Example

src/models/user.rs:

pub struct User {
    pub id: u32,
    pub name: String,
    pub email: String,
    pub age: u32,
    pub bio: Option<String>,
}

data/users.ron:

/* @[crate::models::User] */

User(
    id: 1,
    name: "Alice",
    email: "alice@example.com",
    age: 30,
    bio: Some("Software developer"),
)

Example with Defaults

#[derive(Default, Serialize, Deserialize)]
pub struct Config {
    pub host: String,
    pub port: u16,
    pub max_connections: u32,
    pub debug: bool,
    pub api_key: Option<String>,
    pub allowed_origins: Vec<String>,
}

/* @[crate::models::Config] */
Config(
    // This Config struct has #[derive(Default)]
    // So we can omit fields and they will use their default values
    // The LSP should NOT show warnings for missing fields
    port: 8080,
    debug: true,
)

ron.toml configuration

You can configure default type mappings for RON files using an optional ron.toml file at your project root (next to Cargo.toml).

This lets you omit the Type Annotation in RON files whose paths match a glob pattern which is useful if you have multiple files with the same type (e.g., bevy assets).

Example:

[[types]]
# Matches all files named `post.ron`
glob = "**/post.ron"
# Fully qualified type name
type = "crate::models::Post"

[[types]]
# Matches all files ron files in the `config` directory
glob = "**/config/*.ron"
type = "crate::models::Config"

[[types]]
# Matches all files ending with .user.ron
glob = "**/*.user.ron"
type = "crate::models::User"

Precedence

1. Type annotation in RON file
2. Type declaration in ron.toml, declarations are tested in the order of the file

Editor Integration

Expand a section below for editor-specific instructions.

{
  ...
  "ronLsp.serverPath": "/path/to/ron-lsp"
}

cd jetbrains-plugin
./gradlew buildPlugin

Contributing

Contributions welcome! This is a foundational implementation that can be extended with more features.

License

MIT (except altered Rust logo svg, see below)

Attribution

The logo used in the Jetbrains plugin is a colorized version of the Rust logo which is CC-BY 4.0. See Rust logo specific trademark policy for additional details.