cpp-logger/include/logger/wrapper_object.h

//
//  wrapper_object.hpp
//  logging
//
//  Created by Sam Jaffe on 4/4/19.
//

#pragma once

#include <iostream>
#include <sstream>
#include <string>

#include <json/json.h>

namespace logging { namespace detail {
  class object {
  private:
    void * ptr_;
    std::string (*to_string_)(void *);
    Json::Value (*to_json_)(void *);

  public:
    template <typename T> explicit object(T & object);
    Json::Value json() const { return to_json_(ptr_); }

  private:
    friend std::ostream & operator<<(std::ostream & os, object const & obj) {
      return os << obj.to_string_(obj.ptr_);
    }
    template <typename> static std::string to_string_impl(void * ptr);
    template <typename> static Json::Value to_json_impl(void * ptr);
  };

  template <typename T> void to_stream(T const & obj, std::ostream & os) {
    os << obj;
  }

  template <typename T> std::string to_string(T const & obj) {
    std::stringstream ss;
    to_stream(obj, ss);
    return ss.str();
  }

  template <typename T> Json::Value to_json(T const & obj) {
    return to_string(obj);
  }

  template <typename T> std::string object::to_string_impl(void * ptr) {
    return to_string(*static_cast<T *>(ptr));
  }

  template <typename T> Json::Value object::to_json_impl(void * ptr) {
    return to_json(*static_cast<T *>(ptr));
  }

  template <typename T>
  object::object(T & object)
      : ptr_(&object), to_string_(&object::to_string_impl<T>),
        to_json_(&object::to_json_impl<T>) {}
}}