int DerivedClass1::DoNlpTask(const DerivedReq1& req, DerivedResp* resp);

#include <iostream>
#include <type_traits>

// 以下模擬請(qǐng)求協(xié)議 =====================
class BaseReq {};

class DerivedReq : public BaseReq {};

class BaseResp {};

class DerivedResp : public BaseResp {};

DerivedReq g_derived_req;

// 以下模擬 NLP ============================

class BaseClass {
 public:
  // 單純視為一個(gè)需要重載的函數(shù)
  virtual int get_field_id() = 0;
     
  virtual void WormUp () {}
};

#define REGISTER_PROTOTYPE(req_type, resp_type) \
 public:                                        \
  using ReqType = req_type;                     \
  using RespType = resp_type;

class DerivedClass : public BaseClass {
  // 注冊(cè)請(qǐng)求類型
  REGISTER_PROTOTYPE(DerivedReq, DerivedResp)
 public:
  int DoNlpTask(const DerivedReq&, DerivedResp* resp) {
    std::cout << "Derived DoNlpTask\n";
  }

  int get_field_id() override { return 1; }
};

// 以下模擬pb反射 =========================
const BaseReq* GetReqType() { return &g_derived_req; }

// 以下是 visitor 的定義 ===========
class Visitor {
 public:
  template <typename ClassType>
  int DoVisit(ClassType* base) {
    static_assert(std::is_base_of<BaseClass, DerivedClass>::value,
                  "type failed");
    int idx = base->get_field_id();
    std::cout << "visitor get field_id " << idx << std::endl;
    const auto* req = GetMessageType<typename ClassType::ReqType>(GetReqType());
    typename ClassType::RespType resp;
    // 返回計(jì)算結(jié)果
    return base->DoNlpTask(*req, &resp);
  }

 private:
  template <typename ReqType>
  const ReqType* GetMessageType(const BaseReq* req) {
    static_assert(std::is_base_of<BaseReq, ReqType>::value,
                  "Message Type Error");
    return static_cast<const ReqType*>(req);
  }
};

int main() {
  DerivedClass dc;
  Visitor vis;
  vis.DoVisit(&dc);
  return 0;
}