monaco-language-server

This is a simple language server example in Python.

Supports:

• python (pyls)
• c++ (ccls or clangd)

Usage (Ubuntu as server)

First, Install ccls (or clangd) and confirm ccls --version has output.

sudo apt-get -y ccls
sudo apt-get -y clang-format

Then install requirements:

pip3 install -r requirements.txt

Edit configuration app/config.yml if needed. You can use templates.

debug: yes
host: 127.0.0.1
port: 3000      # change the port if in use
# ...

Run server.py:

python3 -u server.py

The output should look like:

*******************************************
WebSocket Language Server For Monaco Editor
*******************************************
use config: app/config.yaml
current rootUri: app/cpp_workspace

all commands:
  - python: pyls -v
  - cpp: ccls --init={
    "index":{
      "onChange":true,
      "trackDependency":2
    }
  }


Started Web Socket at:
  - python: ws://127.0.0.1:3000/python
  - cpp: ws://127.0.0.1:3000/cpp
Visit http://127.0.0.1:3000/log to see log.

Use SSL Connection

Some website do not accept http websocket, so you need a SSL certificate. You may generate a self-signed certificate for 127.0.0.1, put the cert and key files in ./ssl, and install it as a trusted root certificate, then turn on ssl in config.yml.

Configuration

Formatting

To configure formatting in ccls, just set .clang-format in app/cpp_workspace.

BasedOnStyle: Google
IndentWidth: 4
SortIncludes: false

Node.js Client

Use monaco-languageclient and @codingame/monaco-jsonrpc.

const {
  MonacoLanguageClient,
  CloseAction,
  ErrorAction,
  MonacoServices,
  createConnection,
} = require("monaco-languageclient");

import { listen } from "@codingame/monaco-jsonrpc";

// ...

To use ccls/clangd, files should sycronized to server. server.py provide a /file api to update files.

The client should:

1. connect ws://.../file via WebSocket
2. send message "get_rootUri" to get absolute path of rootUri in MonacoServer

let webSocket = new WebSocket("ws://" + serverHost + "/file");
webSocket.onopen = () => {
  webSocket.send(JSON.stringify({ type: "get_rootUri" }));
};
webSocket.onmessage = (ev) => {
  let message = JSON.parse(ev.data);
  if (message.result == "ok") {
      rootUri = message.data;
  } else {
      // ...
  }
  webSocket.close();
};

3. Use this path as rootUri option:

const { MonacoServices } = require("monaco-languageclient");
MonacoServices.install(monaco, { rootUri });

4. Use file://filename uri to create model:

let model = monaco.editor.createModel(code, language, monaco.Uri.parse("file://" + filename));

5. Update file if monaco editor changed (create if filename not exists)

monaco_model.onDidChangeContent((e) => {
  if (lang == "cpp") {
    console.log("try to update file");
    updateFile(filename, monaco_model.getValue());
  }
});

function updateFile(filename, code) {
  let url = "ws://" + serverHost + "/file";
  if (!!fileWebSocket && fileWebSocket.readyState == fileWebSocket.OPEN) {
    fileWebSocket.send(JSON.stringify({ type: "update", filename, code }));
  } else {
    fileWebSocket = new WebSocket(url);
    fileWebSocket.onopen = (ev) => {
      ev.target.send(JSON.stringify({ type: "update", filename, code }));
    };
    fileWebSocket.onmessage = (ev) => {
      let message = JSON.parse(ev.data);
      if (message.result == "ok") {
        console.log("update file success:", filename);
      } else {
        console.warn("update file failed:", ev);
      }
    };
  }
}