feat: expose default cron implementation

Author: JohnRoesler

example_test.go

@@ -348,6 +348,14 @@ func ExampleMonthlyJob() {
 	)
 }
 
+func ExampleNewDefaultCron() {
+	c := gocron.NewDefaultCron(true)
+	err := c.IsValid("* * * * * *", time.Local, time.Now())
+	if err != nil {
+		panic(err)
+	}
+}
+
 func ExampleNewScheduler() {
 	s, _ := gocron.NewScheduler()
 	defer func() { _ = s.Shutdown() }()

job.go

@@ -140,6 +140,15 @@ func newDefaultCronImplementation(withSeconds bool) Cron {
 	}
 }
 
+// NewDefaultCron returns the default cron implementation for use outside the
+// scheduling of a job. For example, validating crontab syntax before passing to the
+// NewJob function.
+func NewDefaultCron(cronStatementsIncludeSeconds bool) Cron {
+	return &defaultCron{
+		withSeconds: cronStatementsIncludeSeconds,
+	}
+}
+
 var _ Cron = (*defaultCron)(nil)
 
 type defaultCron struct {