This repository contains various tools for working with the Message Format 2 localization system from Unicode.

• mf2lsp: A language server for Message Format 2.
• vscode-mf2: A VS Code extension for Message Format 2.
• mf2_parser: A Rust parser for Message Format 2.
• mf2_printer: A Rust pretty-printer for Message Format 2.

The mf2lsp language server provides language support for Message Format 2 in editors that support the Language Server Protocol. It is implemented in Rust and can be run as a standalone executable or via Wasm (for use in web-based editors).

mf2lsp is still in early development, but it already has a relatively rich feature set:

• Semantic highlighting
• Diagnostics (syntax errors, early errors)
• Variable completion
• Variable rename
• Go to definition for variables
• Quick fixes for some errors
• Formatting

To use mf2lsp in VS Code, you can install the vscode-mf2 extension.

For use in other editors with LSP support, you can run mf2lsp as a standalone executable. You can find the latest release on the releases page.

The vscode-mf2 extension provides support for Message Format 2 in Visual Studio Code. It uses the mf2lsp language server to provide all the features mentioned above, but also includes a language grammar that enables syntax highlighting and bracket matching.

You can install the extension from the Visual Studio Code marketplace: https://marketplace.visualstudio.com/items?itemName=nicolo-ribaudo.vscode-mf2.

To install, you can also press Ctrl+P and then run the ext install nicolo-ribaudo.vscode-mf2 command.

This repository also contains two Rust crates for working with Message Format 2.

The mf2_parser crate provides a parser for the Message Format 2 syntax. It can parse any sequence of Unicode scalar values (valid UTF-8) into an AST representing the Message Format 2 syntax. The parser has very strong error recovery, so it can parse even very broken or incomplete input (like is common in editors).

The mf2_printer crate provides a pretty-printer for the Message Format 2 AST. It can take an AST and convert it back to a string, preserving some of the original formatting (like empty lines).

To build the language server, you will need to have Rust installed. You can build the language server by running:

cargo build

To use your local build of the language server in VS Code, you can set the mf2.server.path option to the path of the built executable. It will be located at <path-to-this-repo>/target/debug/mf2lsp.

You can run tests by running:

cargo test && deno task test

To regenerate expected test output after modifying the parser / ast / printer, run:

UPDATE=1 cargo test