codemirror-lang-terraform

CodeMirror Terraform Language Support

This repository provides a CodeMirror 6 language package for Terraform. It includes:

• A Lezer grammar for Terraform.
• Highlighting, indentation, and folding rules specific to Terraform syntax.
• An easy-to-use extension for CodeMirror 6.

Installation

1. Clone this repository or install from npm (once published):

   npm install codemirror-lang-terraform
   

2. Make sure you have the required CodeMirror 6 packages installed (e.g. @codemirror/language).

Usage

In your CodeMirror setup code, import and include the Terraform language extension:

import { EditorView, basicSetup } from "@codemirror/basic-setup";
import { EditorState } from "@codemirror/state";
import { terraform } from "codemirror-lang-terraform";

const startState = EditorState.create({
  doc: `# Example Terraform code
resource "aws_instance" "web" {
  ami           = "ami-123456"
  instance_type = "t2.micro"
}`,
  extensions: [basicSetup, terraform()],
});

const view = new EditorView({
  state: startState,
  parent: document.querySelector("#editor"),
});

This will enable Terraform syntax highlighting, indentation, and folding while you edit .tf or .tfvars content.

Development

If you want to develop or modify this language package:

1. Clone the repository:

   git clone https://github.com/enoreyes/lang-terraform
   cd lang-terraform
   

2. Install dependencies:

   npm install
   

3. Build the project:

   npm run prepare
   

   This will use Rollup and the Lezer generator to produce compiled parser files in the dist folder.

4. Run tests:

   npm test
   

   Tests are kept in the test directory, where parsing behavior is checked.

Grammar

The Terraform grammar file (src/terraform.grammar) uses Lezer’s grammar syntax to define tokens and parse rules, including interpolation, blocks, attributes, and resource definitions.

Key aspects include:

• Local token contexts for strings, to properly detect interpolation ("${ ... }").
• Precedence rules to handle Terraform operators (+, -, *, /, &&, ||, etc.).
• Nodes for resource, module, provider, data, and other Terraform block types.
• Special highlight styling for resource/module labels.

Contributing

• Fork this repo and make a branch for your feature or bugfix.
• Generate the parser by running npm run prepare and ensure all tests pass with npm test.
• Submit a pull request with your changes.

License

This project is licensed under the MIT License. Please see the license file for more details.