lsp-asun

lsp-asun is the Zig-based language server for ASUN. It also acts as the shared runtime for editor-facing utilities such as formatting, compression, and ASUN/JSON conversion.

It follows the current ASUN syntax: scalar type hints use @, and complex fields keep @{...} / @[...].

What It Does

• Runs a standard Language Server Protocol server over stdio
• Publishes parser and semantic diagnostics
• Provides hover, completion, semantic tokens, and inlay hints
• Formats and compresses ASUN documents
• Converts ASUN to JSON and JSON back to ASUN
• Exposes a WASM build for browser or embedded integrations

Main Capabilities

The native server currently supports:

• textDocument/didOpen
• textDocument/didChange
• textDocument/didClose
• textDocument/hover
• textDocument/completion
• textDocument/formatting
• textDocument/semanticTokens/full
• textDocument/inlayHint
• workspace/executeCommand

The custom commands used by the VS Code extension are:

• asun.compress
• asun.toJSON
• asun.fromJSON

Requirements

• Zig 0.16.0 or newer

The minimum Zig version comes from build.zig.zon.

Build

Build the native binary for your current platform:

cd lsp-asun
zig build

Output:

zig-out/bin/lsp-asun

Build an optimized release binary:

zig build --release=safe

Cross-compile for another target:

zig build -Dtarget=x86_64-linux --release=safe
zig build -Dtarget=aarch64-macos --release=safe

Run

If no transform flag is provided, the binary starts the LSP server over stdio.

./zig-out/bin/lsp-asun

You can also pass the compatibility flag explicitly:

./zig-out/bin/lsp-asun --stdio

Check the version:

./zig-out/bin/lsp-asun --version

CLI Utilities

The same binary can be used as a filter that reads from stdin and writes to stdout.

Format:

printf '%s\n' '{name@str,age@int}:(Alice,30)' | ./zig-out/bin/lsp-asun --format

Compress:

printf '%s\n' '{name@str, age@int}:\n  (Alice, 30)' | ./zig-out/bin/lsp-asun --compress

ASUN to JSON:

printf '%s\n' '{name@str,age@int}:(Alice,30)' | ./zig-out/bin/lsp-asun --to-json

JSON to ASUN:

printf '%s\n' '{"name":"Alice","age":30}' | ./zig-out/bin/lsp-asun --from-json

Test

Run the unit and integration-style tests:

cd lsp-asun
zig build test

WASM Build

Build the WebAssembly artifact:

cd lsp-asun
zig build wasm

Expected output:

zig-out/wasm/asun-lsp.wasm

The native executable is named lsp-asun, while the current WASM artifact is still named asun-lsp.wasm.

The WASM target exposes helpers for:

• validation
• formatting
• compression
• ASUN to JSON
• JSON to ASUN
• basic completion

Integration With The VS Code Extension

The extension under ../plugin_vscode launches this binary over stdio. In practice, packaging usually works like this:

1. Build lsp-asun
2. Copy the binary into plugin_vscode/server/
3. Start it from the extension host with -stdio

The extension also uses workspace/executeCommand to call:

• asun.compress
• asun.toJSON
• asun.fromJSON

Project Layout

lsp-asun/
├── build.zig
├── build.zig.zon
├── src/
│   ├── main.zig
│   ├── server.zig
│   ├── features.zig
│   ├── analyzer.zig
│   ├── lexer.zig
│   ├── parser.zig
│   └── wasm.zig
└── tests/
    └── lsp_test.zig

Notes

• The default transport is stdio.
• Diagnostics include both parse errors and semantic checks.
• This directory is the canonical place for the Zig LSP implementation; editor packaging should treat it as the source of the lsp-asun binary.
• The current WASM output filename is asun-lsp.wasm, which differs from the native executable name.