Tree-sitter LambdaMOO

A Tree-sitter grammar and parser for the LambdaMOO (MOO) scripting language.

This project enables fast, incremental parsing and syntax analysis of MOO code, suitable for syntax highlighting, code navigation, language servers, and editor integration (e.g., Neovim, Helix, Zed, VS Code).

Installation

tree-sitter-lambdamoo is published on npmjs and crates.io, so you can include it directly in your project dependencies without referencing local directory paths.

Node.js (npm)

npm install tree-sitter-lambdamoo

Rust (Cargo)

cargo add tree-sitter-lambdamoo

Go

go get github.com/kruton/tree-sitter-lambdamoo

Features & Grammar Coverage

The grammar (grammar.js) supports standard LambdaMOO syntax.

Repository Structure

Key files:

• grammar.js: Edit this file to add or modify grammar rules.
• queries/highlights.scm: Queries mapping AST nodes to syntax highlight capture groups.
• bindings/rust/lib.rs: Rust API integration.
• bindings/node/index.js: Node.js native module loader.
• bindings/go/binding.go: Go API integration.

Prerequisites

To build and contribute to this repository, ensure you have the following installed:

• Node.js and npm
• Rust Toolchain (cargo, rustc) for building and testing Rust bindings
• C Compiler (gcc, clang, or MSVC) for building native parser binaries
• Tree-sitter CLI: Can be run via npx tree-sitter or installed globally:

  npm install -g tree-sitter-cli
  # or via Cargo:
  cargo install tree-sitter-cli
  

Building and Developing

1. Install Node Dependencies

npm install

2. Generate the Parser

When modifying grammar.js, you must re-generate the C parser files in src/:

npm run build
# or directly with tree-sitter CLI:
npx tree-sitter generate

This updates src/parser.c, src/grammar.json, and src/node-types.json.

3. Running Tests

Rust Tests

To test the Rust binding and verify that parser.c compiles cleanly with C compilers:

cargo test

Go Tests

To test the Go bindings:

go test ./bindings/go/...

Tree-sitter Corpus Tests

To run Tree-sitter parser tests:

npm test
# or:
npx tree-sitter test

4. Parsing MOO Code Interactively

You can test parsing a MOO file or snippet using the CLI:

npx tree-sitter parse path/to/script.moo

Usage Examples

Rust Integration

Add tree-sitter-lambdamoo and tree-sitter to your Cargo.toml:

[dependencies]
tree-sitter = "0.26"
tree-sitter-lambdamoo = "0.1"

In your Rust code:

use tree_sitter::Parser;

fn main() {
    let mut parser = Parser::new();
    let language = tree_sitter_lambdamoo::LANGUAGE;
    parser.set_language(&language.into()).expect("Error loading LambdaMOO grammar");

    let source_code = r#"
        if (player.wizard)
            player:tell("Hello, wizard!");
        endif
    "#;

    let tree = parser.parse(source_code, None).unwrap();
    println!("{}", tree.root_node().to_sexp());
}

Node.js Integration

Install the package via npm:

npm install tree-sitter-lambdamoo

In JavaScript:

const Parser = require('tree-sitter');
const LambdaMOO = require('tree-sitter-lambdamoo');

const parser = new Parser();
parser.setLanguage(LambdaMOO);

const sourceCode = 'return player:location();';
const tree = parser.parse(sourceCode);
console.log(tree.root_node.toString());

Go Integration

Install the packages:

go get github.com/tree-sitter/go-tree-sitter
go get github.com/kruton/tree-sitter-lambdamoo

In Go:

package main

import (
	"fmt"

	tree_sitter "github.com/tree-sitter/go-tree-sitter"
	tree_sitter_lambdamoo "github.com/kruton/tree-sitter-lambdamoo/bindings/go"
)

func main() {
	parser := tree_sitter.NewParser()
	defer parser.Close()

	language := tree_sitter.NewLanguage(tree_sitter_lambdamoo.Language())
	parser.SetLanguage(language)

	sourceCode := []byte("return player:location();")
	tree := parser.Parse(sourceCode, nil)
	defer tree.Close()

	fmt.Println(tree.RootNode().ToSexp())
}

Contributing

1. Modify Grammar: Make updates to rules in grammar.js.
2. Re-generate Parser: Run npx tree-sitter generate to refresh generated files in src/.
3. Add Tests: Add test cases to test/corpus/ following the Tree-sitter test file format.
4. Verify Changes: Run cargo test and npm test to ensure all tests pass cleanly.

License

This project is dual-licensed / distributed under the MIT License