text: // Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
  // Distributed under the MIT License (http://opensource.org/licenses/MIT)
  
  #pragma once
  //
  // base sink templated over a mutex (either dummy or real)
  // concrete implementation should override the sink_it_() and flush_()  methods.
  // locking is taken care of in this class - no locking needed by the
  // implementers..
  //
  
  #include <spdlog/common.h>
  #include <spdlog/details/log_msg.h>
  #include <spdlog/sinks/sink.h>
  
  namespace spdlog {
  namespace sinks {
  template<typename Mutex>
  class base_sink : public sink
  {
  public:
      base_sink();
      explicit base_sink(std::unique_ptr<spdlog::formatter> formatter);
      ~base_sink() override = default;
  
      base_sink(const base_sink &) = delete;
      base_sink(base_sink &&) = delete;
  
      base_sink &operator=(const base_sink &) = delete;
      base_sink &operator=(base_sink &&) = delete;
  
      void log(const details::log_msg &msg) final;
      void flush() final;
      void set_pattern(const std::string &pattern) final;
      void set_formatter(std::unique_ptr<spdlog::formatter> sink_formatter) final;
  
  protected:
      // sink formatter
      std::unique_ptr<spdlog::formatter> formatter_;
      mutable Mutex mutex_;
  
      virtual void sink_it_(const details::log_msg &msg) = 0;
      virtual void flush_() = 0;
      virtual void set_pattern_(const std::string &pattern);
      virtual void set_formatter_(std::unique_ptr<spdlog::formatter> sink_formatter);
  };
  } // namespace sinks
  } // namespace spdlog
  
  #ifdef SPDLOG_HEADER_ONLY
  #    include "base_sink-inl.h"
  #endif
  