Factory method to create worker instances

worker_factory.cc

void Worker::New(const FunctionCallbackInfo<Value>& args) {
  Environment* env = Environment::GetCurrent(args);

  CHECK(args.IsConstructCall());

  if (env->isolate_data()->platform() == nullptr) {
    THROW_ERR_MISSING_PLATFORM_FOR_WORKER(env);
    return;
  }

  std::string url;
  std::shared_ptr<PerIsolateOptions> per_isolate_opts = nullptr;

  std::vector<std::string> exec_argv_out;
  bool has_explicit_exec_argv = false;

  CHECK_EQ(args.Length(), 2);
  // Argument might be a string or URL
  if (!args[0]->IsNullOrUndefined()) {
    Utf8Value value(
        args.GetIsolate(),
        args[0]->ToString(env->context()).FromMaybe(Local<String>()));
    url.append(value.out(), value.length());
    std::cout << "node_worker.cc[Worker::New()] Creating new worker for " << url << "\n";
  }

  if (args[1]->IsArray()) {
    // Check this out later
    Local<Array> array = args[1].As<Array>();
    // The first argument is reserved for program name, but we don't need it
    // in workers.
    has_explicit_exec_argv = true;
    std::vector<std::string> exec_argv = {""};
    uint32_t length = array->Length();
    for (uint32_t i = 0; i < length; i++) {
      Local<Value> arg;
      if (!array->Get(env->context(), i).ToLocal(&arg)) {
        return;
      }
      MaybeLocal<String> arg_v8_string =
          arg->ToString(env->context());
      if (arg_v8_string.IsEmpty()) {
        return;
      }
      Utf8Value arg_utf8_value(
          args.GetIsolate(),
          arg_v8_string.FromMaybe(Local<String>()));
      std::string arg_string(arg_utf8_value.out(), arg_utf8_value.length());
      exec_argv.push_back(arg_string);
    }

    std::vector<std::string> invalid_args{};
    std::vector<std::string> errors{};
    per_isolate_opts.reset(new PerIsolateOptions());

    // Using invalid_args as the v8_args argument as it stores unknown
    // options for the per isolate parser.
    options_parser::Parse(
        &exec_argv,
        &exec_argv_out,
        &invalid_args,
        per_isolate_opts.get(),
        kDisallowedInEnvironment,
        &errors);

    // The first argument is program name.
    invalid_args.erase(invalid_args.begin());
    if (errors.size() > 0 || invalid_args.size() > 0) {
      Local<Value> error;
      if (!ToV8Value(env->context(),
                     errors.size() > 0 ? errors : invalid_args)
                         .ToLocal(&error)) {
        return;
      }
      Local<String> key =
          FIXED_ONE_BYTE_STRING(env->isolate(), "invalidExecArgv");
      // Ignore the return value of Set() because exceptions bubble up to JS
      // when we return anyway.
      USE(args.This()->Set(env->context(), key, error));
      return;
    }
  }
  if (!has_explicit_exec_argv)
    exec_argv_out = env->exec_argv();
  new Worker(env, args.This(), url, per_isolate_opts, std::move(exec_argv_out));
}