DSLX Syntax
Syntax highlighting and basic editing support for Google XLS DSLX in Visual Studio Code. No language server, XLS installation, or runtime dependencies are required.
Features
- Recognizes
.x and .dslx files as DSLX.
- Highlights declarations, keywords, bit types, numeric literals, attributes, macros, and function calls.
- Supports line comments, strings, character literals, multiline backtick strings, and escape sequences.
- Highlights proc and channel constructs, bit slicing, concatenation, and other DSLX operators.
- Provides bracket matching, automatic bracket/quote pairing, and line-comment toggling.
- Keeps primed identifiers such as
value' intact without automatically inserting a closing apostrophe.
fn widen_add(left: u8, right: u8) -> u9 {
(left as u9) + (right as u9)
}
#[test]
fn arithmetic_test() {
assert_eq(widen_add(u8:255, u8:1), u9:256);
}
See examples/highlighting.x for more syntax examples.
Requirements
Visual Studio Code 1.85.0 or later. Node.js is only needed to develop or package the extension, not to use it.
Installation
From a VSIX
- Download a
.vsix file from GitHub Releases, or build one locally using the instructions below.
- Open the Extensions view in VS Code.
- Select Install from VSIX... from the Extensions view menu and choose the file.
From the Marketplace
Once the extension is published, search for @id:kele14x.dslx-syntax in the Extensions view and select Install.
If you installed an earlier build with the ID local.dslx-syntax, uninstall that build before installing kele14x.dslx-syntax to avoid duplicate language registrations.
Usage
Open a .x or .dslx file. The language mode in the status bar should read DSLX. If another extension claims the file type, select the language mode and choose DSLX manually.
Use VS Code's Toggle Line Comment command to add or remove // comments. Highlighting colors depend on your active theme.
This extension uses a TextMate grammar, not a compiler or language server. It does not provide type checking, diagnostics, formatting, semantic completion, or go-to-definition. Syntax highlighting does not guarantee that a program is valid DSLX.
Development
Use Node.js 24 or later.
npm ci
npm test
npm run package
The packaging command runs the grammar tests and creates a dslx-syntax-<version>.vsix file in the repository root.
To run editor integration tests:
npm run test:editor
The editor test runner downloads VS Code when needed and uses an isolated temporary profile. Set VSCODE_EXECUTABLE_PATH to use an existing compatible VS Code executable instead.
To inspect highlighting manually, open this repository in VS Code and press F5 to launch the extension development host with examples/highlighting.x.
Releases
CI runs tests for pushes to main, pull requests, and manual runs. Only a pushed v* tag builds a VSIX and publishes it as a GitHub Release asset; CI does not upload Actions artifacts.
Before releasing, update the version in package.json and package-lock.json, commit the changes, and push a matching tag such as v0.1.1. The workflow rejects a tag that does not match the extension version.
GitHub Releases and the VS Code Marketplace are separate distribution channels. The current workflow does not publish to the Marketplace; upload the release VSIX through your publisher's Marketplace management page.
Feedback
Report highlighting issues with a small DSLX example and your VS Code version in GitHub Issues.
License
MIT. This is an independent extension for DSLX, which is part of the Google XLS project.
