logging.h

// Copyright 2018-2019 Delft University of Technology
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#pragma once
 
#include <iostream>
#include <functional>
#include <string>
#include <utility>
 
namespace cerata {
 
// Log levels.
 
using LogLevel = int;
 
constexpr LogLevel CERATA_LOG_DEBUG = -1;    
constexpr LogLevel CERATA_LOG_INFO = 0;      
constexpr LogLevel CERATA_LOG_WARNING = 1;   
constexpr LogLevel CERATA_LOG_ERROR = 2;     
constexpr LogLevel CERATA_LOG_FATAL = 3;     
 
class Logger {
 public:
  using CallbackSignature = void(LogLevel, const std::string &, char const *, char const *, int);
 
  inline void enable(std::function<CallbackSignature> callback) {
    callback_ = std::move(callback);
  }
 
  inline bool IsEnabled() { return callback_ ? true : false; }
 
  inline void write(LogLevel level,
                    std::string const &message,
                    char const *source_function,
                    char const *source_file,
                    int line_number) {
    if (callback_) {
      callback_(level, message, source_function, source_file, line_number);
    }
  }
 
 private:
  std::function<void(LogLevel, const std::string &, char const *, char const *, int)> callback_;
};
 
inline Logger &logger() {
  static Logger l;
  return l;
}
 
// TODO(johanpel): do we want to throw or exit some other way? For debugging, this is quite handy.
#define CERATA_LOG(level, msg) \
if (CERATA_LOG_##level > CERATA_LOG_WARNING) { \
  throw std::runtime_error(std::string(__FILE__) + ":" \
                          + std::string(__FUNCTION__) + ":" \
                          + std::to_string(__LINE__) + ":\n" + (msg)); \
} else {  \
  logger().write(CERATA_LOG_##level, msg,  __FUNCTION__, __FILE__, __LINE__); \
} \
(void)0
 
}  // namespace cerata