include/Logger.h

#ifndef LOGGER_H_
#define LOGGER_H_

// This macro needs to be defined to inform Boost.Log library that it is linked
// dynamically
#ifndef BOOST_LOG_DYN_LINK
#define BOOST_LOG_DYN_LINK
#endif

#include <boost/log/sinks/sync_frontend.hpp>
#include <boost/log/sinks/text_ostream_backend.hpp>
#include <boost/log/sources/record_ostream.hpp>
#include <boost/log/sources/severity_feature.hpp>
#include <boost/log/sources/severity_logger.hpp>
#include <boost/smart_ptr/shared_ptr.hpp>


class Logger {
 public:
  enum class SeverityLevel : int {
    kTrace = 0,
    kDebug,
    kInfo,
    kWarning,
    kError
  };

  struct _TimeStamp {};

  using logger_t = boost::log::sources::severity_logger<SeverityLevel>;

  ~Logger() noexcept;

  static logger_t &Get() {
    return GetInstance().logger_;
  }

  static void SetLevel(SeverityLevel threshold);

  static _TimeStamp TimeStamp() {
    return {};
  };

 private:
  Logger();
  Logger(Logger const &) = delete;
  Logger &operator=(Logger const &) = delete;

  static Logger &GetInstance() {
    static Logger instance;
    return instance;
  }

  logger_t logger_;

  boost::shared_ptr<boost::log::sinks::synchronous_sink<
    boost::log::sinks::text_ostream_backend>> sink_;
};


#define LOG_TRACE \
  BOOST_LOG_SEV(Logger::Get(), Logger::SeverityLevel::kTrace)

#define LOG_DEBUG \
  BOOST_LOG_SEV(Logger::Get(), Logger::SeverityLevel::kDebug)

#define LOG_INFO  \
  BOOST_LOG_SEV(Logger::Get(), Logger::SeverityLevel::kInfo)

#define LOG_WARN  \
  BOOST_LOG_SEV(Logger::Get(), Logger::SeverityLevel::kWarning)

#define LOG_ERROR \
  BOOST_LOG_SEV(Logger::Get(), Logger::SeverityLevel::kError)


boost::log::basic_record_ostream<char> &operator<<(
    boost::log::basic_record_ostream<char> &stream, Logger::_TimeStamp (*)());

#endif  // LOGGER_H_

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