cpp-logger/logger.cpp

//
//  Logger.cpp
//  DanmakuRPG
//
//  Created by Sam Jaffe on 7/18/15.
//  Copyright (c) 2015 Sam Jaffe. All rights reserved.
//

#ifdef _WIN32
#include <Windows.h>
#endif

#include <cassert>
#include <cmath>
#include <ctime>
#include <map>
#include <stdexcept>

#include "logger.hpp"
#include "properties.hpp"

namespace logging {
#define X(l) \
case logging::L##l: \
return #l;
  
  const char* level_header(log_level l) {
    assert(l != logging::LNONE);
    switch (l) {
        X(FATAL)
        X(CRITICAL)
        X(ERROR)
        X(WARNING)
        X(INFO)
        X(DEBUG)
        X(TRACE)
        X(NONE)
    }
  }
  
#undef X
  
  std::string timestamp() {
    time_t round = std::time(NULL);
    struct tm time = *std::localtime(&round);
    char buf[32];
    snprintf(buf, sizeof(buf), "%0.4d-%0.2d-%0.2d %0.2d:%0.2d:%0.2d.%0.3d ",
             1900 + time.tm_year, time.tm_mon + 1, time.tm_mday,
             time.tm_hour, time.tm_min, time.tm_sec,
             static_cast<int>(round % 1000));
    return buf;
  }
}

namespace logging {
  class multiple_bindings : public std::logic_error {
    using std::logic_error::logic_error;
  };
  
//  extern logger_impl& _logger_impl_shared_instance();
  extern _binding _default_logger_impl;
  static _binding _impl_binding = nullptr;
  
  bool bind_logger_impl(_binding impl) {
    assert(_impl_binding == nullptr);
    if (_impl_binding != nullptr) {
      throw multiple_bindings{"Only one logger implementation may be bound"};
    }
    _impl_binding = impl;
    return true;
  }
  
  logger_impl& _get_shared_instance() {
    if (_impl_binding == nullptr) {
      return _default_logger_impl();
    } else {
      return _impl_binding();
    }
  }
}

namespace logging {
  logger& logger::instance() {
    static logger instance;
    return instance;
  }
  
  logger& logger::instance(const char* name) {
    static std::map<const char*, std::unique_ptr<logger>> instances;
    std::map<const char*, std::unique_ptr<logger>>::iterator it;
    if ((it = instances.find(name)) != instances.end()) {
      return *(it->second);
    }
    return *(instances.emplace(std::make_pair(name, std::unique_ptr<logger>(new logger(name)))).first->second);
  }

  
  logger::logger(const char* name)
  : min_level_(LDEBUG)
  , logger_name_(name)
  , impl_(_get_shared_instance())
  {
  }
  
  logger::~logger() {
    flush();
  }
  
  std::string logger::get_header(log_level level) {
    std::string ts = timestamp();
    char data[64];
    snprintf(data, sizeof(data), "[%-5s] %s %s - ", level_header(level), logger_name_, ts.c_str());
    return data;
  }
  
  void logger::vlognf(log_level level, size_t num_bytes, char const* fmt, va_list args) {
    if (level < min_level_) return;
    const std::unique_ptr<char[]> data(new char[num_bytes]);
    int n = vsnprintf(data.get(), num_bytes, fmt, args);
    if (n >= 0) {
      data[num_bytes-1] = '\0';
      log(level, get_header(level) + data.get());
    }
  }
  
  void logger::log(log_level level, std::string const& msg) {
    impl_.write(level, msg);
  }
  
  void logger::flush() {
    impl_.flush();
  }
}