log

type Entry struct {
	Level   Level     // log level.
	Time    time.Time // time of the log event.
	Message string    // log message (optional).
	Fields  Fields    // extra fields of the log entry (optional).
}

type Fields map[string]interface{}

type Formatter interface {
	// Format formats a log entry.
	// Format writes formatted entry to the w.
	Format(w io.Writer, entry *Entry) error
}

type LTSVFormatter struct {
}

type Level uint32

type Logger interface {
	// Debug calls Logger.Output to print to the logger with DEBUG level.
	// Arguments are handled in the manner of fmt.Print.
	// If the current log level is upper than DEBUG, it won't be the output.
	Debug(v ...interface{})

	// Debugf calls Logger.Output to print to the logger with DEBUG level.
	// Arguments are handled in the manner of fmt.Printf.
	// If the current log level is upper than DEBUG, it won't be the output.
	Debugf(format string, v ...interface{})

	// Debugln calls Logger.Output to print to the logger with DEBUG level.
	// Arguments are handled in the manner of fmt.Println.
	// If the current log level is upper than DEBUG, it won't be the output.
	Debugln(v ...interface{})

	// Info calls Logger.Output to print to the logger with INFO level.
	// Arguments are handled in the manner of fmt.Print.
	// If the current log level is upper than INFO, it won't be the output.
	Info(v ...interface{})

	// Infof calls Logger.Output to print to the logger with INFO level.
	// Arguments are handled in the manner of fmt.Printf.
	// If the current log level is upper than INFO, it won't be the output.
	Infof(format string, v ...interface{})

	// Infoln calls Logger.Output to print to the logger with INFO level.
	// Arguments are handled in the manner of fmt.Println.
	// If the current log level is upper than INFO, it won't be the output.
	Infoln(v ...interface{})

	// Warn calls Logger.Output to print to the logger with WARN level.
	// Arguments are handled in the manner of fmt.Print.
	// If the current log level is upper than WARN, it won't be the output.
	Warn(v ...interface{})

	// Warnf calls Logger.Output to print to the logger with WARN level.
	// Arguments are handled in the manner of fmt.Printf.
	// If the current log level is upper than WARN, it won't be the output.
	Warnf(format string, v ...interface{})

	// Warnln calls Logger.Output to print to the logger with WARN level.
	// Arguments are handled in the manner of fmt.Println.
	// If the current log level is upper than WARN, it won't be the output.
	Warnln(v ...interface{})

	// Error calls Logger.Output to print to the logger with ERROR level.
	// Arguments are handled in the manner of fmt.Print.
	// If the current log level is upper than ERROR, it won't be the output.
	Error(v ...interface{})

	// Errorf calls Logger.Output to print to the logger with ERROR level.
	// Arguments are handled in the manner of fmt.Printf.
	// If the current log level is upper than ERROR, it won't be the output.
	Errorf(format string, v ...interface{})

	// Errorln calls Logger.Output to print to the logger with ERROR level.
	// Arguments are handled in the manner of fmt.Println.
	// If the current log level is upper than ERROR, it won't be the output.
	Errorln(v ...interface{})

	// Fatal calls Logger.Output to print to the logger with FATAL level.
	// Arguments are handled in the manner of fmt.Print.
	// Also calls os.Exit(1) after the output.
	Fatal(v ...interface{})

	// Fatalf calls Logger.Output to print to the logger with FATAL level.
	// Arguments are handled in the manner of fmt.Printf.
	// Also calls os.Exit(1) after the output.
	Fatalf(format string, v ...interface{})

	// Fatalln calls Logger.Output to print to the logger with FATAL level.
	// Arguments are handled in the manner of fmt.Println.
	// Also calls os.Exit(1) after the output.
	Fatalln(v ...interface{})

	// Panic calls Logger.Output to print to the logger with PANIC level.
	// Arguments are handled in the manner of fmt.Print.
	// Also calls panic() after the output.
	Panic(v ...interface{})

	// Panicf calls Logger.Output to print to the logger with PANIC level.
	// Arguments are handled in the manner of fmt.Printf.
	// Also calls panic() after the output.
	Panicf(format string, v ...interface{})

	// Panicln calls Logger.Output to print to the logger with PANIC level.
	// Arguments are handled in the manner of fmt.Println.
	// Also calls panic() after the output.
	Panicln(v ...interface{})

	// Print calls Logger.Output to print to the logger with NONE level.
	// Arguments are handled in the manner of fmt.Print.
	Print(v ...interface{})

	// Printf calls Logger.Output to print to the logger with NONE level.
	// Arguments are handled in the manner of fmt.Printf.
	Printf(format string, v ...interface{})

	// Println calls Logger.Output to print to the logger with NONE level.
	// Arguments are handled in the manner of fmt.Println.
	Println(v ...interface{})

	// Output writes the output for a logging event with the given level.
	// The given message will be format by Formatter. Also a newline is appended
	// to the message before the output.
	Output(level Level, message string)

	// With returns a new Logger with fields.
	With(fields Fields) Logger

	// Level returns the current log level.
	Level() Level

	// SetLevel sets the log level.
	SetLevel(level Level)
}

type RawFormatter struct{}