SystemJ for VS Code

Basic language support for .sysj files (the SystemJ GALS reactive/synchronous language): syntax highlighting and snippets. This is a "Tier 1" extension — a TextMate grammar plus snippets, no language server, no semantic analysis. It doesn't understand your code; it just makes it easier to read than plain text.

What it does

• Highlights SystemJ control constructs: input/output signal, emit, await, abort, present, sustain, pause, loop, and the || parallel-block operator.
• Highlights the embedded Java (keywords, types, strings, numbers, comments, method calls) since a .sysj reaction body is Java with SystemJ constructs woven in.
• Highlights #signalName value reads and the ModuleName( ports ) -> { ... } module header.
• Comment toggling (//, /* */), bracket matching/auto-closing, and basic brace-based indentation.
• Snippets for the common constructs (module, abort, await, present, sustain, loop, par, plus an emithold snippet for the time-bounded "hold a signal instead of a single racy tick" pattern used for cross-clock-domain signals).

What it does not do

No parsing, no completion beyond static snippets, no diagnostics, no go-to-definition. That would require a real language server built on the SystemJ grammar (sjc) — a much bigger project than this one.

Try it locally

1. Open this folder in VS Code.
2. Press F5 (or Run > Start Debugging) to launch an Extension Development Host.
3. Open any .sysj file in that host window — highlighting and snippets are active immediately.

Install without publishing

npm install -g @vscode/vsce
vsce package

This produces a .vsix file. Install it with:

code --install-extension systemj-language-0.1.0.vsix

Notes on the grammar

There's no separate SystemJ tokenizer here — the grammar rules were derived by reading the .sysj sources and the SystemJ language reference directly (module header syntax, input/output [Type] signal declarations, abort/await/present/sustain/pause/loop, and the || parallel-thread operator), then falling back to generic Java-style rules (keywords, types, strings, numbers, comments) for the embedded reaction code. Extend syntaxes/systemj.tmLanguage.json if you add constructs (e.g. trap/exit/select) that aren't used yet in this project's .sysj files.