Add a logger class

src/logger/logger.hpp

@@ -0,0 +1,70 @@
+#ifndef LOGGER_INCLUDED
+# define LOGGER_INCLUDED
+
+/**
+ * Singleton used in logger macros to write into files or stdout, with
+ * various levels of severity.
+ * Only the macros should be used.
+ * @class Logger
+ */
+
+#include <memory>
+#include <iostream>
+#include <fstream>
+
+#define debug_lvl 0
+#define info_lvl 1
+#define warning_lvl 2
+#define error_lvl 3
+
+// Macro defined to get the filename instead of the full path. But if it is
+// not properly defined by the build system, we fallback to __FILE__
+#ifndef __FILENAME__
+# define __FILENAME__ __FILE__
+#endif
+
+#define WHERE\
+  __FILENAME__ << ":" << __LINE__
+
+#define log_debug(text)\
+  Logger::instance()->get_stream(debug_lvl) << "[DEBUG]:" << WHERE << ":\t" << text << std::endl;
+
+#define log_info(text)\
+  Logger::instance()->get_stream(info_lvl) << "[INFO]:" << WHERE << ":\t" << text << std::endl;
+
+#define log_warning(text)\
+  Logger::instance()->get_stream(warning_lvl) << "[WARNING]:" << WHERE << ":\t" << text << std::endl;
+
+#define log_error(text)\
+  Logger::instance()->get_stream(error_lvl) << "[ERROR]:" << WHERE << ":\t" << text << std::endl;
+
+/**
+ * Juste a structure representing a stream doing nothing with its input.
+ */
+class nullstream: public std::ostream
+{
+public:
+  nullstream():
+    std::ostream(0)
+  { }
+};
+
+class Logger
+{
+public:
+  static std::unique_ptr<Logger>& instance();
+  std::ostream& get_stream(const int);
+  Logger(const int log_level, const std::string& log_file);
+  Logger(const int log_level);
+
+private:
+  Logger(const Logger&);
+  Logger& operator=(const Logger&);
+
+  const int log_level;
+  std::ofstream ofstream;
+  nullstream null_stream;
+  std::ostream stream;
+};
+
+#endif // LOGGER_INCLUDED