previous method

LocalDate previous(DayOfWeek targetDayOfWeek)

Returns the previous LocalDate falling on the specified DayOfWeek. This is a strict 'previous' - if this date on already falls on the target day of the week, the returned value will be a week earlier.

• targetDayOfWeek: The ISO day of the week to return the previous date of.

Returns: The previous LocalDate falling on the specified day of the week.

• InvalidOperationException: The underlying calendar doesn't use ISO days of the week.
• ArgumentOutOfRangeException: targetDayOfWeek is not a valid day of the week (Monday to Sunday).

Implementation

LocalDate previous(DayOfWeek targetDayOfWeek) {
  // Avoids boxing...
  if (targetDayOfWeek < DayOfWeek.monday ||
      targetDayOfWeek > DayOfWeek.sunday) {
    throw RangeError('targetDayOfWeek');
  }
  // This will throw the desired exception for calendars with different week systems.
  DayOfWeek thisDay = dayOfWeek;
  int difference = targetDayOfWeek - thisDay;
  if (difference >= 0) {
    difference -= 7;
  }
  return addDays(difference);
}