babel-cli\src\babel\util.js

export function transform(filename, code, opts) {
  opts = defaults(opts || {}, index.opts);
  opts.filename = filename;

  const result = babel.transform(code, opts);
  result.filename = filename;
  result.actual = code;
  return result;
}

export function compile(filename, opts) {
  try {
    const code = fs.readFileSync(filename, "utf8");
    return transform(filename, code, opts);
  } catch (err) {
    if (commander.watch) {
      console.error(toErrorStack(err));
      return { ignored: true };
    } else {
      throw err;
    }
  }
}