Adds whole years, quarters or months to the fields of a naive datetime, keeping its time of day: the add/9 callback CalendarInterval steps an interval of a year or a month with. The date moves as shift/6 moves it, clamping the day into a shorter month.

Arguments

• year, month and day are the date's fields in this calendar.

• hour, minute, second and microsecond are the time of day, returned unchanged.

• precision is :year, :quarter or :month.

• step is the number of years, quarters or months to add, which may be negative.

Returns

• {year, month, day, hour, minute, second, microsecond}.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {year, month, day, 12, 30, 0, {0, 0}} =
...>   Calendrical.Chinese.add(date.year, date.month, date.day, 12, 30, 0, {0, 0}, :month, 1)
iex> {year, month, day} == Calendrical.Chinese.shift(date.year, date.month, date.day, :months, 1, [])
true

Returns what this calendar's year is built of, :month or :week, as its info/0 states.

Returns

• :week for a calendar whose year is built of weeks.

• :month otherwise.

Examples

iex> Calendrical.Chinese.calendar_base() in [:month, :week]
true

Returns the calendar module whose CLDR calendar type is the one given, whichever calendar is asked (Calendrical.calendar_from_cldr_calendar_type/1).

Arguments

• calendar_type is a CLDR calendar type as an atom or a string.

Returns

• {:ok, calendar_module}, or

• {:error, exception} for a calendar type no calendar module has.

Examples

iex> Calendrical.Chinese.calendar_from_cldr_calendar_type(:gregorian)
{:ok, Calendrical.Gregorian}

iex> {:error, %Localize.UnknownCalendarError{}} =
...>   Calendrical.Chinese.calendar_from_cldr_calendar_type(:not_a_calendar)

Returns the day a date is written with: the day of its written_date/3.

Arguments

• year, month and day are a date of this calendar.

Returns

• The day of the date's written_date/3, or

• {:error, %Calendrical.InvalidDateError{}} for a date the calendar does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {_year, _month, written_day} = Calendrical.Chinese.written_date(date.year, date.month, date.day)
iex> Calendrical.Chinese.cardinal_day(date.year, date.month, date.day) == written_day
true

Returns the CLDR month a month of the year names without a year (Calendrical.Month.cldr_month/2).

Arguments

• month is a month of this calendar.

Returns

• The CLDR month the month is named in the year that holds 1 January 2000, the month itself in the Hebrew calendar, whose names depend on the year, and the month itself where the reference year has no such month.

Examples

iex> {:ok, date} = Date.convert(~D[2000-01-01], Calendrical.Chinese)
iex> Calendrical.Chinese.cardinal_month(1) == Calendrical.Chinese.cldr_month(date.year, 1)
true

Returns the year a date is written with: the year of its written_date/3.

Arguments

• year, month and day are a date of this calendar.

Returns

• The year of the date's written_date/3, or

• {:error, %Calendrical.InvalidDateError{}} for a date the calendar does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {written_year, _month, _day} = Calendrical.Chinese.written_date(date.year, date.month, date.day)
iex> Calendrical.Chinese.cardinal_year(date.year, date.month, date.day) == written_year
true

Returns the CLDR calendar type whose data names this calendar's months, days and quarters, as its info/0 states.

Returns

• A CLDR calendar type such as :gregorian or :hebrew.

Examples

iex> Calendrical.Chinese.cldr_calendar_type() == Calendrical.Chinese.info().cldr_calendar_type
true

Returns the CLDR calendar type whose data names a date's months and days: the member in effect on the date in a composite calendar, and this calendar's own otherwise (Calendrical.Info.cldr_calendar_type/4).

Arguments

• year, month and day are a date of this calendar.

Returns

• A CLDR calendar type.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> in_effect = Calendrical.Info.in_effect(Calendrical.Chinese, date.year, date.month, date.day)
iex> Calendrical.Chinese.cldr_calendar_type(date.year, date.month, date.day) == in_effect.cldr_calendar_type()
true

Returns the CLDR month of a month of a year (Calendrical.Month.cldr_month/3).

Arguments

• year and month are a month of this calendar.

Returns

• A CLDR month number, or {month, :leap} where the month's name has a leap form, or

• {:error, exception} for a month the year does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> cldr_month = Calendrical.Chinese.cldr_month(date.year, date.month)
iex> Calendrical.Chinese.written_month_from_cldr_month(date.year, cldr_month) ==
...>   Calendrical.Chinese.numeric_month(date.year, date.month, date.day)
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidMonthError{}} = Calendrical.Chinese.cldr_month(date.year, 99)

@spec cycle_and_year(Calendar.year()) :: {integer(), 1..60} | {:error, Exception.t()}

Returns the sexagenary cycle a year of this calendar is in, and the year of the cycle it is.

Arguments

• year is a year of this calendar.

Returns

• {cycle, cyclic_year}, the cycle counted from 2637 BCE, the first year of the first cycle, and the year of it, 1 to 60, as Calendrical.Era.cyclic_year/4 gives it, or

• {:error, %Calendrical.InvalidDateError{}} for a year that is not an integer.

Examples

iex> {:ok, date} = Date.convert(~D[2026-03-01], Calendrical.Chinese)
iex> Calendrical.Chinese.cycle_and_year(date.year)
{78, 43}

Returns the cyclic year of a date (Calendrical.Era.cyclic_year/4).

Arguments

• year, month and day are a date of this calendar.

Returns

• The date's place in the sexagenary cycle, 1 to 60, in an East Asian calendar, and its year in a calendar whose years run in no such cycle, or

• {:error, %Calendrical.InvalidDateError{}} for a year the calendar does not have, or

• {:error, exception}, a Calendrical.MissingFieldsError, for no year.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> cyclic_year = Calendrical.Chinese.cyclic_year(date.year, date.month, date.day)
iex> cyclic_year in 1..60 or cyclic_year == date.year
true

iex> {:error, %Calendrical.MissingFieldsError{}} = Calendrical.Chinese.cyclic_year(nil, 1, 1)

Returns the date of this calendar that written figures name (date_from_written_date/3), as fields.

Arguments

• year, month and day are the figures a date is written with, as written_date/3 returns them.

Returns

• {year, month, day}, the date of this calendar, or

• {:error, %Calendrical.InvalidDateError{}} where the figures name no date.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {year, month, day} = Calendrical.Chinese.written_date(date.year, date.month, date.day)
iex> Calendrical.Chinese.date_from_cardinal_date(year, month, day) == {date.year, date.month, date.day}
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.date_from_cardinal_date(date.year, 0, 1)

Returns the date of a day of a year, counted from the year's first day.

Arguments

• year is a year of this calendar.

• day_of_year is the day of the year, counted from 1.

Returns

• A Date.t/0 of this calendar, or

• {:error, %Calendrical.InvalidDateError{}} for a day the year does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> day_of_year = Calendrical.Chinese.day_of_year(date.year, date.month, date.day)
iex> Calendrical.Chinese.date_from_day_of_year(date.year, day_of_year) == date
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.date_from_day_of_year(date.year, 1000)

Returns the date of a day of a week of a week-year (Calendrical.Week.date_from_week_date/4).

Arguments

• week_year is a week-year of this calendar.

• week is a week of the week-year.

• day is the day of the week, numbered from 1 for the day the calendar's weeks begin on.

Returns

• A Date.t/0 of this calendar, or

• {:error, %Calendrical.InvalidDateError{}} where the week has no such day.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {week_year, week, day} = Calendrical.Chinese.week_date_from_date(date.year, date.month, date.day)
iex> Calendrical.Chinese.date_from_week_date(week_year, week, day) == date
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.date_from_week_date(date.year, 1, 8)

Returns the date of this calendar that written figures name: the inverse of written_date/3.

Arguments

• year is a year of this calendar.

• lunar_month is a traditional month, or {month, :leap}.

• day is a day of the month.

Returns

• {:ok, {year, month, day}} with the ordinal month.

• {:error, :invalid_date} for figures that name no date, an atom as Calendrical.date_from_written_date/3 answers.

Examples

iex> {:ok, today} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {year, month, day} = Calendrical.Chinese.written_date(today.year, today.month, today.day)
iex> Calendrical.Chinese.date_from_written_date(year, month, day)
{:ok, {today.year, today.month, today.day}}

Returns the dates of this calendar, earliest first, whose month and day are those given and that fall in a Gregorian year.

Arguments

• gregorian_year is the Gregorian year to search within.

• month and day are a month and a day of this calendar.

Returns

• A list of zero, one or two Date.t/0 of this calendar, earliest first, since this calendar's years and the Gregorian years drift.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> date in Calendrical.Chinese.dates_in_gregorian_year(2024, date.month, date.day)
true

Returns the days a month of a year has, as runs of their numbers (Calendrical.Month.day_numbers/3).

Arguments

• year and month are a month of this calendar.

Returns

• A list of ranges: one from 1 in every month of every calendar but a composite, whose month a change of calendar falls in has the days that are left, and [] for a month the year does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.day_numbers(date.year, date.month) ==
...>   [1..Calendrical.Chinese.days_in_month(date.year, date.month)//1]
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.day_numbers(date.year, 99)
[]

Returns the day of era and era of a date (Calendrical.Era.day_of_era/4).

Arguments

• year, month and day are a date of this calendar.

Returns

• {day_of_era, era}, where the day of the era counts from the era's first day, or

• {:error, %Calendrical.InvalidDateError{}} for a date the calendar does not have, or

• {:error, exception}, a Calendrical.MissingFieldsError, for a missing field.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {day_of_era, era} = Calendrical.Chinese.day_of_era(date.year, date.month, date.day)
iex> {_year_of_era, year_era} = Calendrical.Chinese.year_of_era(date.year, date.month, date.day)
iex> day_of_era >= 1 and era == year_era
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.day_of_era(date.year, date.month, 0)

Returns the day of the week of a date (Calendrical.Week.day_of_week/5).

Arguments

• year, month and day are a date of this calendar.

• starting_on is :default for the day this calendar's weeks begin on, or the name of a weekday, :monday to :sunday.

Returns

• {day_of_week, 1, 7}, the day numbered from the day the week begins on, or

• {:error, %Calendrical.InvalidDateError{}} for a date the calendar does not have, or

• {:error, exception}, a Calendrical.MissingFieldsError, for a missing field.

Examples

# 1 June 2024 is a Saturday
iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.day_of_week(date.year, date.month, date.day, :monday)
{6, 1, 7}

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.day_of_week(date.year, date.month, 0, :monday)

Returns the day of the year of a date (Calendrical.Period.day_of_year/4).

Arguments

• year, month and day are a date of this calendar.

Returns

• The day of the year, counted from 1 for its first day, or

• {:error, %Calendrical.InvalidDateError{}} for a date the calendar does not have, or

• {:error, exception}, a Calendrical.MissingFieldsError, for a missing field.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> first_day = Calendrical.Chinese.year(date.year).first
iex> Calendrical.Chinese.day_of_year(date.year, date.month, date.day) == Date.diff(date, first_day) + 1
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.day_of_year(date.year, date.month, 0)

Returns the number of days in a month without a year (Calendrical.Month.days_in_month/2).

Arguments

• month is a month of this calendar.

Returns

• The number of days where the month has as many in every year, or

• {:ambiguous, lengths} where its length depends on the year, the lengths a range or, where they are not consecutive, a list, or

• {:error, %Calendrical.NotDefinedError{}} for a month the calendar has in no year, or

• {:error, exception}, a Calendrical.MissingFieldsError, where the month is nil.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {fewest, most} = Calendrical.Chinese.days_in_month_bounds(date.month)
iex> case Calendrical.Chinese.days_in_month(date.month) do
...>   days when is_integer(days) -> fewest == days and most == days
...>   {:ambiguous, lengths} -> Enum.min(lengths) == fewest and Enum.max(lengths) == most
...> end
true

iex> {:error, %Calendrical.NotDefinedError{}} = Calendrical.Chinese.days_in_month(99)

@spec days_in_month(Calendar.year(), Calendar.month()) ::
  Calendar.day() | {:error, Exception.t()}

Returns the number of days in a month of a year, 29 or 30.

Arguments

• year is a year of this calendar.

• month is an ordinal month of the year.

Returns

• 29 or 30, or

• {:error, %Calendrical.InvalidMonthError{}} for a month the year does not have, or

• {:error, %Calendrical.UnsupportedDateRangeError{}} for a year outside the supported years (see the module documentation), or

• {:error, %Calendrical.MissingFieldsError{}} where the year or the month is nil.

Examples

iex> {:ok, today} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.days_in_month(today.year, today.month) in [29, 30]
true

Returns the fewest and the most days a month has in any year (Calendrical.Month.days_in_month_bounds/2).

Arguments

• month is a month of this calendar.

Returns

• {fewest, most}, or

• {:error, exception} for a month the calendar has in no year.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {fewest, most} = Calendrical.Chinese.days_in_month_bounds(date.month)
iex> Calendrical.Chinese.days_in_month(date.year, date.month) in fewest..most
true

iex> {:error, %Calendrical.InvalidMonthError{}} = Calendrical.Chinese.days_in_month_bounds(99)

Returns the number of days in a week.

Returns

• 7.

Examples

iex> Calendrical.Chinese.days_in_week()
7

Returns the number of days in a year (Calendrical.Period.days_in_year/2).

Arguments

• year is a year of this calendar.

Returns

• The number of days, or

• {:error, %Calendrical.InvalidDateError{}} for a year the calendar does not have, or

• {:error, exception}, a Calendrical.MissingFieldsError, for no year.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.days_in_year(date.year) == Enum.count(Calendrical.Chinese.year(date.year))
true

iex> {:error, %Calendrical.MissingFieldsError{}} = Calendrical.Chinese.days_in_year(nil)

Returns the number of whole years, quarters, months, weeks or days from one date to another, the months counted through the leap months of the years between.

Arguments

• from is a {year, month, day} of this calendar.

• to is a {year, month, day} of this calendar.

• date_part is one of :years, :quarters, :months, :weeks or :days.

Returns

• The number of whole units, negative when to is before from, or

• {:error, %Calendrical.InvalidDateError{}} for a from or to the calendar does not have, {:error, %Calendrical.MissingFieldsError{}} for one missing a field, or {:error, %Calendrical.InvalidPartError{}} for a date_part other than the five.

Examples

iex> {:ok, today} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.diff({today.year, 1, 1}, {today.year + 1, 1, 1}, :years)
1

@spec dragon_festival_for_gregorian_year(Calendar.year()) :: Date.t()

Returns the gregorian date of the dragon festival (5th day of 5th lunar month) for a given gregorian year.

Arguments

• year is any year in the Gregorian calendar.

Returns

• The gregorian date of the dragon festival for the given year.

Examples

iex> Calendrical.Chinese.dragon_festival_for_gregorian_year(2021)
~D[2021-06-14]

iex> Calendrical.Chinese.dragon_festival_for_gregorian_year(2022)
~D[2022-06-03]

iex> Calendrical.Chinese.dragon_festival_for_gregorian_year(2023)
~D[2023-06-22]

@spec elapsed_years(integer(), integer()) :: Calendar.year() | {:error, Exception.t()}

Returns the year of this calendar that a sexagenary cycle and a year of it name: the inverse of cycle_and_year/1.

Arguments

• cycle is a sexagenary cycle, counted from 2637 BCE, the first year of the first cycle.

• cyclic_year is a year of the cycle, 1 to 60.

Returns

• The year of this calendar, or

• {:error, %Calendrical.InvalidDateError{}} for a cycle that is not an integer or a cyclic year that is not one of 1 to 60.

Examples

iex> year = Calendrical.Chinese.elapsed_years(78, 43)
iex> {:ok, new_year} = Calendrical.Chinese.new(year, 1, 1)
iex> Date.convert!(new_year, Calendar.ISO).year
2026

iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.elapsed_years(78, 61)

Returns the epoch of this calendar: the ISO day number of its first day.

Returns

• The epoch as an integer number of days since the ISO epoch.

Examples

iex> Calendrical.Chinese.epoch() |> is_integer()
true

Returns the CLDR calendar type that names this calendar's eras, as its info/0 states.

Returns

• A CLDR calendar type such as :gregorian or :japanese.

Examples

iex> Calendrical.Chinese.era_calendar_type() == Calendrical.Chinese.info().era_calendar_type
true

Returns the extended year of a date (Calendrical.Era.extended_year/4).

Arguments

• year, month and day are a date of this calendar.

Returns

• The year numbered without a gap at 0, so that in a calendar with no year 0 the year before 1 is 0, or

• {:error, %Calendrical.InvalidDateError{}} for a date the calendar does not have, or

• {:error, exception}, a Calendrical.MissingFieldsError, for no year.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.extended_year(date.year, date.month, date.day) == date.year
true

iex> {:error, %Calendrical.MissingFieldsError{}} = Calendrical.Chinese.extended_year(nil, 1, 1)

Returns the Gregorian date of a traditional lunar month and day in the lunar year that begins in a Gregorian year.

Arguments

• gregorian_year is a Gregorian year.

• lunar_month is a traditional month, 1 to 12, or {month, :leap}.

• lunar_day is a day of the month.

Returns

• A Date.t/0 in Calendar.ISO.

Raises Calendrical.InvalidDateError when the lunar year has no such month, or the month no such day, and Calendrical.UnsupportedDateRangeError for a Gregorian year outside -20,000 to 20,000.

Examples

iex> %Date{calendar: Calendar.ISO, year: 2024} = Calendrical.Chinese.gregorian_date_for_lunar(2024, 1, 1)

iex> Calendrical.Chinese.gregorian_date_for_lunar(2024, 1, 40)
** (Calendrical.InvalidDateError) [gregorian_year: 2024, lunar_month: 1, lunar_day: 40] is not a date

Returns the static facts about this calendar, as Calendrical.Info.t/0.

Returns

• A Calendrical.Info.t/0 describing this calendar.

Examples

iex> Calendrical.Chinese.info().calendar
Calendrical.Chinese

Returns the ISO 8601 week-year and week of the day a date names (Calendrical.Week.iso_week_of_year/4).

Arguments

• year, month and day are a date of this calendar.

Returns

• {week_year, week} of ISO 8601, or

• {:error, exception} for a date the calendar does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.iso_week_of_year(date.year, date.month, date.day)
{2024, 22}

Returns the position of the year's leap month, or nil.

Arguments

• year is a year of this calendar.

Returns

• The ordinal month that is the leap month, counting it among the year's months, or nil if the year has none, as for anything but an integer year.

Raises Calendrical.UnsupportedDateRangeError for a year outside the supported years (see the module documentation).

Examples

iex> {:ok, today} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.leap_month(today.year) in [nil | Enum.to_list(2..13)]
true

Returns whether a month of a year is the leap month.

Arguments

• year is a year of this calendar.

• month is an ordinal month of the year, counting the leap month.

Returns

• true if the month is the year's leap month, otherwise false, as it is for anything but an integer year.

Raises Calendrical.UnsupportedDateRangeError for a year outside the supported years (see the module documentation).

Examples

iex> {:ok, today} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.leap_month?(today.year, 0)
false

Returns whether a year has thirteen months.

Arguments

• year is a year of this calendar.

Returns

• true if the year has thirteen months, otherwise false.

Raises Calendrical.UnsupportedDateRangeError for a year outside the supported years (see the module documentation).

Examples

iex> {:ok, today} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.leap_year?(today.year) == (Calendrical.Chinese.months_in_year(today.year) == 13)
true

Returns the traditional month at a position in a year (Calendrical.Month.traditional_month/3), or an error for a place the year does not have.

Arguments

• year and month are a month of this calendar.

Returns

• The month's traditional number, or {month, :leap} for a leap month, or

• {:error, %Calendrical.InvalidMonthError{}} for a month the year does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.lunar_month_of_year(date.year, date.month) ==
...>   Calendrical.Chinese.traditional_month(date.year, date.month)
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidMonthError{}} = Calendrical.Chinese.lunar_month_of_year(date.year, 99)

Returns the days of a month of a year (Calendrical.Period.month/3).

Arguments

• year and month are a month of this calendar.

Returns

• A Date.Range.t/0, or

• {:error, %Calendrical.InvalidDateError{}} for a month the year does not have, or

• {:error, exception}, a Calendrical.MissingFieldsError, for a missing year or month.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> date in Calendrical.Chinese.month(date.year, date.month)
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.month(date.year, 99)

Returns the position of a traditional month in a year (Calendrical.Month.month_from_traditional/3).

Arguments

• year is a year of this calendar.

• traditional_month is a month's traditional number, or {month, :leap} for a leap month.

Returns

• The month's position in the year, or

• {:error, exception} where the year has no such month.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> traditional_month = Calendrical.Chinese.traditional_month(date.year, date.month)
iex> Calendrical.Chinese.month_from_traditional(date.year, traditional_month) == date.month
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidMonthError{}} = Calendrical.Chinese.month_from_traditional(date.year, 99)

Returns the months a year has, as runs of their numbers (Calendrical.Month.month_numbers/2).

Arguments

• year is a year of this calendar.

Returns

• A list of ranges: one from 1 in every year of every calendar but a composite, whose year a change of calendar falls in has the months that are left, and [] for a year the calendar does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.month_numbers(date.year) == [1..Calendrical.Chinese.months_in_year(date.year)//1]
true

Returns the CLDR month of a month of a year: the index of its name in this calendar's CLDR data, with {month, :leap} where the name has a leap form (Calendrical.Month.cldr_month/3).

Arguments

• year, month and day are a date of this calendar. The year and the day may be nil: a month's name needs only the month.

Returns

• A CLDR month number, or {month, :leap}, or

• {:error, %Calendrical.InvalidDateError{}} for a day the month does not have, or

• {:error, exception} for a month the year does not have, or a Calendrical.MissingFieldsError where the month is nil.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.month_of_year(date.year, date.month, date.day) == Calendrical.Chinese.cldr_month(date.year, date.month)
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.month_of_year(date.year, date.month, 0)

Returns the number of months in a leap year: the most months a year of this calendar has.

Returns

• A positive integer.

Examples

iex> Calendrical.Chinese.months_in_leap_year() >= Calendrical.Chinese.months_in_ordinary_year()
true

Returns the number of months in an ordinary year: the fewest months a year of this calendar has.

Returns

• A positive integer.

Examples

iex> Calendrical.Chinese.months_in_ordinary_year() <= Calendrical.Chinese.months_in_leap_year()
true

Returns the number of months in a year without a year: the count where every year has as many, {:ambiguous, range} where a leap year has more, and {:error, %Calendrical.NotDefinedError{}} for a composite calendar (Calendrical.Info.months_in_year/1).

Returns

• The number of months where every year has as many, or

• {:ambiguous, fewest..most} where a leap year has more, or

• {:error, %Calendrical.NotDefinedError{}} for a composite calendar, whose bounds months_in_year_bounds/0 gives.

Examples

iex> case Calendrical.Chinese.months_in_year() do
...>   months when is_integer(months) -> months == Calendrical.Chinese.months_in_leap_year()
...>   {:ambiguous, fewest..most//1} -> {fewest, most} == Calendrical.Chinese.info().months_in_year
...>   {:error, %Calendrical.NotDefinedError{}} -> is_list(Calendrical.Chinese.info().members)
...> end
true

Returns the number of months in a given year.

Arguments

• year is the year in this calendar.

Returns

• The number of months in the year, as a positive integer, or

• {:error, %Calendrical.MissingFieldsError{}} where year is nil, or

• {:error, %Calendrical.InvalidDateError{}} where year is no integer.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.months_in_year(date.year) >= date.month
true

Returns the fewest and the most months a year has (Calendrical.Month.months_in_year_bounds/1).

Returns

• {fewest, most}, which in a composite calendar counts the months left in a year a change of calendar falls in.

Examples

iex> {fewest, most} = Calendrical.Chinese.months_in_year_bounds()
iex> fewest <= Calendrical.Chinese.months_in_ordinary_year() and
...>   most >= Calendrical.Chinese.months_in_leap_year()
true

Converts ISO days and a day fraction to a naive datetime of this calendar, as Calendar.naive_datetime_from_iso_days/1 asks.

Arguments

• iso_days is {days, {parts_in_day, parts_per_day}}, a day and a fraction of it.

Returns

• {year, month, day, hour, minute, second, microsecond} of this calendar.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {year, month, day, 12, 0, 0, {0, 6}} =
...>   Calendrical.Chinese.naive_datetime_from_iso_days({739403, {43200000000, 86400000000}})
iex> {year, month, day} == {date.year, date.month, date.day}
true

Converts a naive datetime of this calendar to ISO days and a day fraction, as Calendar.naive_datetime_to_iso_days/7 asks.

Arguments

• year, month and day are a date of this calendar.

• hour, minute, second and microsecond are a time of day, the microsecond as {microseconds, precision}.

Returns

• {iso_days, {parts_in_day, parts_per_day}}.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.naive_datetime_to_iso_days(date.year, date.month, date.day, 12, 0, 0, {0, 6})
{739403, {43200000000, 86400000000}}

Returns the days of a named month in a year (Calendrical.Month.named_month/3).

Arguments

• year is a year of this calendar.

• named_month is the CLDR month that names the month.

Returns

• A list of Date.Range.t/0, one for each counted month that carries the name, earliest first, and [] where none does.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> cldr_month = Calendrical.Chinese.cldr_month(date.year, date.month)
iex> Calendrical.Chinese.named_month(date.year, cldr_month) |> Enum.any?(&(date in &1))
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.named_month(date.year, 99)
[]

Returns a date of this calendar from a year, a traditional lunar month and a day.

Arguments

• year is a year of this calendar.

• lunar_month is a traditional month, 1 to 12, or {month, :leap} for the leap month that follows it.

• day is a day of the month.

Returns

• {:ok, date} with the date in this calendar, or

• {:error, %Calendrical.InvalidDateError{}} for what is no date, or

• {:error, %Calendrical.UnsupportedDateRangeError{}} for a year outside the supported years.

Examples

iex> {:ok, today} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:ok, %Date{month: 1, day: 1}} = Calendrical.Chinese.new(today.year, 1, 1)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.new(today.year, 1, 31)

Returns a date of this calendar from a year, a traditional lunar month and a day, raising for what is no date (see new/3).

Arguments

• year is a year of this calendar.

• lunar_month is a traditional month, 1 to 12, or {month, :leap} for the leap month that follows it.

• day is a day of the month.

Returns

• The Date.t/0 in this calendar.

Raises Calendrical.InvalidDateError for what is no date, and Calendrical.UnsupportedDateRangeError for a year outside the supported years.

Examples

iex> {:ok, today} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> %Date{month: 1, day: 1} = Calendrical.Chinese.new!(today.year, 1, 1)

Returns the Gregorian date of the new year that begins the lunar year of a Gregorian year.

Arguments

• gregorian_year is a Gregorian year.

Returns

• A Date.t/0 in Calendar.ISO.

Examples

iex> Calendrical.Chinese.new_year_for_gregorian_year(2024) == Calendrical.Chinese.gregorian_date_for_lunar(2024, 1, 1)
true

Returns the number a date's month is written with in figures: the month of its written_date/3.

Arguments

• year, month and day are a date of this calendar.

Returns

• The month of the date's written_date/3: a month number, or {month, :leap} for a leap month of a lunisolar calendar, or

• {:error, %Calendrical.InvalidDateError{}} for a date the calendar does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {_year, written_month, _day} = Calendrical.Chinese.written_date(date.year, date.month, date.day)
iex> Calendrical.Chinese.numeric_month(date.year, date.month, date.day) == written_month
true

Returns the position in a year of a traditional month (Calendrical.Month.month_from_traditional/3), as {:ok, month}.

Arguments

• year is a year of this calendar.

• traditional_month is a month's traditional number, or {month, :leap} for a leap month.

Returns

• {:ok, month}, the month's position in the year, or

• {:error, %Calendrical.InvalidMonthError{}} for a month or a leap month the year does not have.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> traditional_month = Calendrical.Chinese.traditional_month(date.year, date.month)
iex> Calendrical.Chinese.ordinal_month_from_traditional(date.year, traditional_month) == {:ok, date.month}
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidMonthError{}} = Calendrical.Chinese.ordinal_month_from_traditional(date.year, 99)

Parses a date written in this calendar's own notation.

Arguments

• string is a date written YYYY-MM-DD, with a leading - for a year before 1, or, in a calendar of weeks, YYYY-Www-D.

Returns

• {:ok, {year, month, day}}, or

• {:error, :invalid_format} where the text is not in that form or its fields are not digits, or

• {:error, :invalid_date} where the text names no date of this calendar.

The reason is an atom, not an exception, because Calendar.parse_date/1 requires one: Date.from_iso8601/2 reads it.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.parse_date(Date.to_string(date)) == {:ok, {date.year, date.month, date.day}}
true

iex> Calendrical.Chinese.parse_date("not a date")
{:error, :invalid_format}

Parses a naive datetime written in this calendar's own notation.

Arguments

• string is a date as parse_date/1 reads it, then T or a space and a time of day.

Returns

• {:ok, {year, month, day, hour, minute, second, microsecond}}, or

• {:error, reason}, such as :invalid_format or :invalid_date, where the text is no such datetime.

The reason is an atom, not an exception, because Calendar.parse_naive_datetime/1 requires one: NaiveDateTime.from_iso8601/2 reads it.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.parse_naive_datetime(Date.to_string(date) <> "T12:00:00") ==
...>   {:ok, {date.year, date.month, date.day, 12, 0, 0, {0, 0}}}
true

iex> Calendrical.Chinese.parse_naive_datetime("2024-06-01")
{:error, :invalid_format}

Parses a UTC datetime written in this calendar's own notation.

Arguments

• string is a date as parse_date/1 reads it, then T or a space, a time of day and an offset from UTC, Z or ±HH:MM.

Returns

• {:ok, {year, month, day, hour, minute, second, microsecond}, offset}, the datetime in UTC and the offset in seconds it was written with, or

• {:error, reason}, such as :invalid_format, :invalid_date or :missing_offset, where the text is no such datetime.

The reason is an atom, not an exception, because Calendar.parse_utc_datetime/1 requires one: DateTime.from_iso8601/2 reads it.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.parse_utc_datetime(Date.to_string(date) <> "T12:00:00Z") ==
...>   {:ok, {date.year, date.month, date.day, 12, 0, 0, {0, 0}}, 0}
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.parse_utc_datetime(Date.to_string(date) <> "T12:00:00")
{:error, :missing_offset}

Returns the calendar a date written for this calendar is parsed in, as its info/0 states.

Returns

• A calendar module.

Examples

iex> Calendrical.Chinese.parsing_calendar() == Calendrical.Chinese.info().parsing_calendar
true

Returns the calendars a date written for this calendar may be written in: the members of a composite calendar, and this calendar alone otherwise (Calendrical.Info.parsing_calendars/1).

Returns

• A non-empty list of calendar modules, the members of a composite calendar in the order they take effect.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> in_effect = Calendrical.Info.in_effect(Calendrical.Chinese, date.year, date.month, date.day)
iex> in_effect in Calendrical.Chinese.parsing_calendars()
true

Returns the number of periods in a year: its months.

Arguments

• year is a year of this calendar.

Returns

• The number of months in the year, as months_in_year/1 returns it.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.periods_in_year(date.year) == Calendrical.Chinese.months_in_year(date.year)
true

Returns the days of a quadrimester of a year (Calendrical.Period.quadrimester/3).

Arguments

• year is a year of this calendar.

• quadrimester is the quadrimester, 1 to 3.

Returns

• A Date.Range.t/0, or

• {:error, %Calendrical.InvalidDateError{}} for a quadrimester or a year the calendar does not have, or

• {:error, %Calendrical.MissingFieldsError{}} where the year or the quadrimester is nil.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.quadrimester(date.year, 1).first == Calendrical.Chinese.year(date.year).first
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.quadrimester(date.year, 4)

Returns the days of a quarter of a year (Calendrical.Period.quarter/3).

Arguments

• year is a year of this calendar.

• quarter is the quarter, 1 to 4.

Returns

• A Date.Range.t/0, or

• {:error, %Calendrical.InvalidDateError{}} for a quarter or a year the calendar does not have, or

• {:error, %Calendrical.MissingFieldsError{}} where the year or the quarter is nil.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> quarter = Calendrical.Chinese.quarter_of_year(date.year, date.month, date.day)
iex> date in Calendrical.Chinese.quarter(date.year, quarter)
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.quarter(date.year, 5)

Returns the quarter of the year a date falls in (Calendrical.Period.quarter_of_year/4).

Arguments

• year, month and day are a date of this calendar.

Returns

• The quarter, 1 to 4, or

• {:error, %Calendrical.InvalidDateError{}} for a date the calendar does not have, or

• {:error, exception}, a Calendrical.MissingFieldsError, for a missing year or month.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.quarter_of_year(date.year, date.month, date.day) in 1..4
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.quarter_of_year(date.year, date.month, 0)

Returns the related Gregorian year of a date (Calendrical.Era.related_gregorian_year/4).

Arguments

• year, month and day are a date of this calendar.

Returns

• The Gregorian year the date's calendar year begins in, or

• {:error, %Calendrical.InvalidDateError{}} for a year the calendar does not have, or

• {:error, exception}, a Calendrical.MissingFieldsError, for no year.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:ok, first_day} = Date.convert(Calendrical.Chinese.year(date.year).first, Calendrical.Gregorian)
iex> Calendrical.Chinese.related_gregorian_year(date.year, date.month, date.day) == first_day.year
true

Returns the days of a semester of a year (Calendrical.Period.semester/3).

Arguments

• year is a year of this calendar.

• semester is the semester, 1 or 2.

Returns

• A Date.Range.t/0, or

• {:error, %Calendrical.InvalidDateError{}} for a semester or a year the calendar does not have, or

• {:error, %Calendrical.MissingFieldsError{}} where the year or the semester is nil.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.semester(date.year, 1).first == Calendrical.Chinese.year(date.year).first
true

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> {:error, %Calendrical.InvalidDateError{}} = Calendrical.Chinese.semester(date.year, 3)

Returns the date a number of years, quarters, months, weeks or days on from a date of this calendar, by position, with the traditional month kept across years and a day the resulting month lacks clamped to its last day unless clamp: false (Calendrical.Shift.shift/7).

Arguments

• year, month and day are a date of this calendar.

• date_part is one of :years, :quarters, :months, :weeks or :days.

• increment is the number of units, which may be negative.

• options is a keyword list of options.

Options

• :clamp is whether a day the resulting month lacks becomes its last day. The default is true.

Returns

• {year, month, day} of this calendar, or

• {:error, %Calendrical.InvalidDateError{}} where year, month and day are no date of this calendar, or

• {:error, %Calendrical.MissingFieldsError{}} where a field is nil.

Examples

iex> {:ok, date} = Date.convert(~D[2024-06-01], Calendrical.Chinese)
iex> Calendrical.Chinese.shift(date.year, date.month, date.day, :days, 0)
{date.year, date.month, date.day}