Identifies that this calendar is month based.

@spec calendar_year(year(), month(), day()) :: Calendar.year()

Returns the calendar year as displayed on rendered calendars.

Defines the CLDR calendar type for this calendar.

This type is used in support of Cldr.Calendar.localize/3. Currently only :gregorian is supported.

@spec cyclic_year(year(), month(), day()) :: Calendar.year()

Returns the cyclic year as displayed on rendered calendars.

Returns a {year, month, day} calculated from the number of iso_days.

Returns the number of days since the calendar epoch for a given year-month-day

@spec day_of_era(year(), month(), day()) :: {day :: pos_integer(), era :: 0..1}

Calculates the day and era from the given year, month, and day.

@spec day_of_week(year(), month(), day(), 1..7 | :default) ::
  {Calendar.day_of_week(), first_day_of_week :: non_neg_integer(),
   last_day_of_week :: non_neg_integer()}

Calculates the day of the week from the given year, month, and day. It is an integer from 1 to 7, where 1 is Monday and 7 is Sunday.

@spec day_of_year(year(), month(), day()) :: 1..366

Calculates the day of the year from the given year, month, and day.

@spec days_in_month(month()) :: Calendar.day()

Returns how many days there are in the given month.

If the days in month cannot be determined without knowning the year and error tuple is returned.

@spec days_in_month(year(), month()) :: 28..31

Returns how many days there are in the given year-month.

Returns the number days in a a week.

Returns the number days in a given year.

@spec extended_year(year(), month(), day()) :: Calendar.year()

Returns the extended year as displayed on rendered calendars.

@spec iso_week_of_year(year(), month(), day()) :: {:error, :not_defined}

Calculates the ISO week of the year from the given year, month, and day. It is an integer from 1 to 53.

@spec leap_year?(year()) :: boolean()

Returns if the given year is a leap year.

Returns a Date.Range.t representing a given month of a year.

@spec month_of_year(year(), month(), day()) :: month()

Calculates the month of the year from the given year, month, and day. It is an integer from 1 to 12.

@spec naive_datetime_from_iso_days(Calendar.iso_days()) ::
  {Calendar.year(), Calendar.month(), Calendar.day(), Calendar.hour(),
   Calendar.minute(), Calendar.second(), Calendar.microsecond()}

Converts the Calendar.iso_days/0 format to the datetime format specified by this calendar.

@spec naive_datetime_to_iso_days(
  Calendar.year(),
  Calendar.month(),
  Calendar.day(),
  Calendar.hour(),
  Calendar.minute(),
  Calendar.second(),
  Calendar.microsecond()
) :: Calendar.iso_days()

Returns the Calendar.iso_days/0 format of the specified date.

Calculates the number of period in a given year. A period corresponds to a month in month-based calendars and a week in week-based calendars..

Adds an increment number of date_parts to a year-month-day.

date_part can be :quarters or:months.

Returns a Date.Range.t representing a given quarter of a year.

@spec quarter_of_year(year(), month(), day()) :: 1..4

Calculates the quarter of the year from the given year, month, and day. It is an integer from 1 to 4.

@spec related_gregorian_year(year(), month(), day()) :: Calendar.year()

Returns the related gregorian year as displayed on rendered calendars.

Determines if the date given is valid according to this calendar.

Returns a Date.Range.t representing a given week of a year.

@spec week_of_month(year(), month(), day()) ::
  {pos_integer(), pos_integer()} | {:error, :not_defined}

Calculates the week of the year from the given year, month, and day. It is an integer from 1 to 53.

@spec week_of_year(year(), month(), day()) :: {:error, :not_defined}

Calculates the week of the year from the given year, month, and day. It is an integer from 1 to 53.

Returns a Date.Range.t representing a given year.

@spec year_of_era(year()) :: {year(), era :: 0..1}

Calculates the year and era from the given year. The ISO calendar has two eras: the current era which starts in year 1 and is defined as era "1". And a second era for those years less than 1 defined as era "0".

@spec year_of_era(year(), month(), day()) :: {year :: Calendar.year(), era :: 0..1}

Calculates the year and era from the given year, month and day.