[boost variant example]boost::variant example #boost #variant

boost_variant_example.cpp

#include <boost/variant.hpp>
#include <string>
#include <iostream>

using data_t = boost::variant<
  bool,
  int8_t,
  uint8_t,
  int16_t,
  uint16_t,
  int32_t,
  uint32_t,
  int64_t,
  uint64_t,
  float,
  double,
  std::string>;

enum class DataType { /* use type_t */
    kBool,
    kInt8,
    kUint8,
    kInt16,
    kUint16,
    kInt32,
    kUint32,
    kInt64,
    kUint64,
    kFloat,
    kDouble,
    kString,

    kSize  /* not type, denote the size */
};

using type_t = DataType;

template <class T>
bool getBaseData(type_t type, data_t param, T& t) {
    switch (type) {
    case type_t::kBool: {
        t = boost::get<bool>(param);
        break;
    }

    case type_t::kInt8: {
        t = boost::get<int8_t>(param);
        break;
    }

    case type_t::kUint8: {
        t = boost::get<uint8_t>(param);
        break;
    }

    case type_t::kInt16: {
        t = boost::get<int16_t>(param);
        break;
    }

    case type_t::kUint16: {
        t = boost::get<uint16_t>(param);
        break;
    }

    case type_t::kInt32: {
        t = boost::get<int32_t>(param);
        break;
    }

    case type_t::kUint32: {
        t = boost::get<uint32_t>(param);
        break;
    }

    case type_t::kInt64: {
        t = boost::get<int64_t>(param);
        break;
    }

    case type_t::kUint64: {
        t = boost::get<uint64_t>(param);
        break;
    }

    case type_t::kString: {
        // t = boost::get<std::string>(param);
        break;
    }

    default: {
        return false;
    }

    }
    return true;
}

void getStringData(type_t type, data_t param, std::string &str) {
  str = boost::get<std::string>(param);
} 

int main()
{
  data_t stringData = "hello";
  data_t doubleData = 3.1415926;
  double dData;
  std::string strData;
  
  getBaseData(type_t::kDouble, doubleData, dData);
  getStringData(type_t::kString, stringData, strData);
  
  std::cout <<"dData:" <<dData <<", strData:" <<strData <<std::endl;
  
  return 0; 
}