/// <summary>
/// Crontab schedule
/// </summary>
/// <param name="expression">expression</param>
private CrontabSchedule(string expression)
{
Debug.Assert(expression != null);
var fields = expression.Split((char[])Separators, StringSplitOptions.RemoveEmptyEntries);
if (fields.Length != 5)
{
throw new FormatException(string.Format(
"'{0}' is not a valid crontab expression. It must contain at least 5 components of a schedule "
+ "(in the sequence of minutes, hours, days, months, days of week).",
expression));
}
_minutes = CrontabField.Minutes(fields[0]);
_hours = CrontabField.Hours(fields[1]);
_days = CrontabField.Days(fields[2]);
_months = CrontabField.Months(fields[3]);
_daysOfWeek = CrontabField.DaysOfWeek(fields[4]);
}