feat: add trhee log levels

CHANGELOG.md

@@ -2,6 +2,13 @@
 
 ## Unreleased
 
+## v0.4.0 (2020-05-17)
+
+- Add three new log levels: `Trace`, `Notice` and `Alert` with the following
+  order: `Trace`, `Debug`, `Info`, `Notice`, `Warning`, `Error`, `Critical`,
+  `Alert`, `Fatal`.
+  As Syslog has no equivalent of `Trace`, it is mapped to `Debug`.
+
 ## v0.3.0 (2020-05-17)
 
 ### Incompatible Changes

backend_syslog_linux.go

@@ -52,16 +52,20 @@ func (sb *SyslogBackend) Write(r *Record) error {
 	text := sb.formatter(r)
 
 	switch r.Level {
-	case Debug:
+	case Trace, Debug:
 		err = sb.w.Debug(text)
 	case Info:
 		err = sb.w.Info(text)
+	case Notice:
+		err = sb.w.Notice(text)
 	case Warning:
 		err = sb.w.Warning(text)
 	case Error:
 		err = sb.w.Err(text)
 	case Critical:
 		err = sb.w.Crit(text)
+	case Alert:
+		err = sb.w.Alert(text)
 	case Fatal:
 		err = sb.w.Emerg(text)
 	}

logger.go

@@ -88,6 +88,17 @@ func (l *Logger) Log(level Level, m string) {
 	}
 }
 
+// Trace logs a message with the Trace level.
+func (l *Logger) Trace(text string) {
+	l.Log(Trace, text)
+}
+
+// Tracef formats the message with given args and logs the result with the
+// Trace level.
+func (l *Logger) Tracef(text string, args ...interface{}) {
+	l.Trace(fmt.Sprintf(text, args...))
+}
+
 // Debug logs a message with the Debug level.
 func (l *Logger) Debug(text string) {
 	l.Log(Debug, text)
@@ -110,6 +121,17 @@ func (l *Logger) Infof(text string, args ...interface{}) {
 	l.Info(fmt.Sprintf(text, args...))
 }
 
+// Notice logs a message with the Notice level.
+func (l *Logger) Notice(text string) {
+	l.Log(Notice, text)
+}
+
+// Noticef formats the message with given args and logs the result with the
+// Notice level.
+func (l *Logger) Noticef(text string, args ...interface{}) {
+	l.Notice(fmt.Sprintf(text, args...))
+}
+
 // Warning logs a message with the Warning level.
 func (l *Logger) Warning(text string) {
 	l.Log(Warning, text)
@@ -143,6 +165,17 @@ func (l *Logger) Criticalf(text string, args ...interface{}) {
 	l.Critical(fmt.Sprintf(text, args...))
 }
 
+// Alert logs a message with the Alert level.
+func (l *Logger) Alert(text string) {
+	l.Log(Alert, text)
+}
+
+// Alertf formats the message with given args and logs the result with the.
+// Alert level.
+func (l *Logger) Alertf(text string, args ...interface{}) {
+	l.Alert(fmt.Sprintf(text, args...))
+}
+
 // Fatal logs a message with the Fatal level.
 func (l *Logger) Fatal(text string) {
 	l.Log(Debug, text)

logging.go

@@ -38,11 +38,14 @@ type Level byte
 
 //revive:disable:exported
 const (
-	Debug Level = iota
+	Trace Level = iota
+	Debug
 	Info
+	Notice
 	Warning
 	Error
 	Critical
+	Alert
 	Fatal
 	DefaultLevel = Info
 )
@@ -50,7 +53,10 @@ const (
 //revive:enable:exported
 
 //nolint:gochecknoglobals // designed this way
-var levelNames = [6]string{"DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL", "FATAL"}
+var levelNames = [...]string{
+	"TRACE", "DEBUG", "INFO", "NOTICE", "WARNING",
+	"ERROR", "CRITICAL", "ALERT", "FATAL",
+}
 
 // Name returns the name of the log level.
 func (l Level) Name() string {