logger.hpp

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// Copyright Global Phasing Ltd.
//
// Logger - a tiny utility for passing messages through a callback.
 
#ifndef GEMMI_LOGGER_HPP_
#define GEMMI_LOGGER_HPP_
 
#include <cstdio>      // for fprintf
#include <functional>  // for function
#include "fail.hpp"    // for GEMMI_COLD
#include "util.hpp"    // for cat
 
namespace gemmi {
 
struct Logger {
  std::function<void(const std::string&)> callback;
  int threshold = 6;
 
  void suspend() { threshold -= 100; }
  void resume()  { threshold += 100; }
 
  template<int N, class... Args> void level(Args const&... args) const {
    if (threshold >= N && callback)
      callback(cat(args...));
  }
 
  template<class... Args> void debug(Args const&... args) const { level<8>("Debug: ", args...); }
  template<class... Args> void mesg(Args const&... args) const { level<6>(args...); }
  template<class... Args> void note(Args const&... args) const { level<5>("Note: ", args...); }
 
  template<class... Args> GEMMI_COLD void err(Args const&... args) const {
    if (threshold >= 3) {
      std::string msg = cat(args...);
      if (callback == nullptr)
        fail(msg);
      callback("Warning: " + msg);
    }
  }
 
  // predefined callbacks
 
  static void to_stderr(const std::string& s) {
    std::fprintf(stderr, "%s\n", s.c_str());
  }
  static void to_stdout(const std::string& s) {
    std::fprintf(stdout, "%s\n", s.c_str());
  }
};
 
} // namespace gemmi
#endif