@ublitzjs/dev-comments/mjs/worker.mjs


import fs from "node:fs";
import { workerData, parentPort } from "node:worker_threads";
import path from "node:path";

const { input, output } = workerData;

const START_TAG = "/*_START_DEV_*/";
const END_TAG = "/*_END_DEV_*/";

await fs.promises.mkdir(path.dirname(output), { recursive: true });

const rs = fs.createReadStream(input, { encoding: "utf8", highWaterMark: 20 });
const ws = fs.createWriteStream(output, { encoding: "utf8" });

let buffer = ""; // holds leftover across chunks
let state = "KEEPING"; // or "DELETING"

rs.on("data", (chunk) => {
  buffer += chunk;
  let idx;

  while (true) {
    if (state === "KEEPING") {
      idx = buffer.indexOf(START_TAG);
      if (idx === -1) {
        // No START tag – flush all except trailing possible START_TAG prefix
        const safeEnd = buffer.length - START_TAG.length + 1;
        if (safeEnd > 0) {
          ws.write(buffer.slice(0, safeEnd));
          buffer = buffer.slice(safeEnd);
        }
        break;
      } else {
        // Found START tag
        ws.write(buffer.slice(0, idx));
        buffer = buffer.slice(idx + START_TAG.length);
        state = "DELETING";
      }
    } else {
      idx = buffer.indexOf(END_TAG);
      if (idx === -1) {
        // Not found yet – trim buffer to last possible END_TAG start
        buffer = buffer.slice(-END_TAG.length + 1);
        break;
      } else {
        buffer = buffer.slice(idx + END_TAG.length);
        state = "KEEPING";
      }
    }
  }
});

rs.on("end", () => {
  if (state === "KEEPING" && buffer.length > 0) {
    ws.write(buffer);
  }
  ws.end(() => parentPort.postMessage(`${input} → ${output}`));
});

rs.on("error", (err) => parentPort.postMessage(`Read error: ${err}`));
ws.on("error", (err) => parentPort.postMessage(`Write error: ${err}`));