Get started with a prettier server package

Co-Authored-By: Antonio Scandurra <antonio@zed.dev>

crates/prettier/prettier_server/src/index.js

@@ -0,0 +1,56 @@
+const { Buffer } = require('buffer');
+
+let buffer = Buffer.alloc(0);
+process.stdin.resume();
+process.stdin.on('data', (data) => {
+    buffer = Buffer.concat([buffer, data]);
+    handleData();
+});
+process.stdin.on('end', () => {
+    handleData();
+});
+
+function handleData() {
+    if (buffer.length < 4) {
+        return;
+    }
+
+    const length = buffer.readUInt32LE(0);
+    console.log(length);
+    if (buffer.length < 4 + length) {
+        return;
+    }
+
+    const bytes = buffer.subarray(4, 4 + length);
+    buffer = buffer.subarray(4 + length);
+
+    try {
+        const message = JSON.parse(bytes);
+        handleMessage(message);
+    } catch (_) {
+        sendResponse(makeError("Request JSON parse error"));
+        return;
+    }
+}
+
+// format
+// clear_cache
+// shutdown
+// error
+
+function handleMessage(message) {
+    console.log(message);
+    sendResponse({ method: "hi", result: null });
+}
+
+function makeError(message) {
+    return { method: "error", message };
+}
+
+function sendResponse(response) {
+    let message = Buffer.from(JSON.stringify(response));
+    let length = Buffer.alloc(4);
+    length.writeUInt32LE(message.length);
+    process.stdout.write(length);
+    process.stdout.write(message);
+}