# `Calendrical.Roc` Implementation of the Republic of China (Minguo) calendar. The ROC calendar is the proleptic Gregorian calendar with year numbering starting from the founding of the Republic of China on **1 January 1912**: roc_year = gregorian_year - 1911 So 1 ROC = 1912 CE and 113 ROC = 2024 CE. The calendar is the official calendar of Taiwan and is also used in some legal contexts in mainland China for documents that pre-date 1949. Months and leap years follow the standard proleptic Gregorian rules exactly. Day boundaries are at midnight. ## Reference - CLDR `:roc` calendar type. The CLDR era data places the start of the *Minguo Era* (`:roc`) at proleptic Gregorian `1912-01-01` and the *Before R.O.C.* era (`:broc`) at all earlier dates. # `day` ```elixir @type day() :: 1..31 ``` # `month` ```elixir @type month() :: 1..12 ``` # `year` ```elixir @type year() :: integer() ``` # `calendar_base` Identifies whether this calendar is month or week based. # `calendar_year` ```elixir @spec calendar_year(Calendar.year(), Calendar.month(), Calendar.day()) :: Calendar.year() ``` Returns the calendar year as displayed on rendered calendars. # `cldr_calendar_type` Defines the CLDR calendar type for this calendar. This type is used in support of `Calendrical. localize/3`. # `cyclic_year` ```elixir @spec cyclic_year(Calendar.year(), Calendar.month(), Calendar.day()) :: Calendar.year() ``` Returns the cyclic year as displayed on rendered calendars. # `date_from_iso_days` ```elixir @spec date_from_iso_days(integer()) :: {year(), month(), day()} ``` Returns a ROC `{year, month, day}` tuple for the given ISO day number. ### Arguments * `iso_days` is an integer count of days since the proleptic ISO epoch. ### Returns * A three-tuple `{year, month, day}` in the ROC calendar. ### Examples iex> Calendrical.Roc.date_from_iso_days(739_252) {113, 1, 2} # `date_to_iso_days` ```elixir @spec date_to_iso_days(year(), month(), day()) :: integer() ``` Returns the number of ISO days for the given ROC `year`, `month`, and `day`. ### Arguments * `year` is any ROC year as an integer. * `month` is a month in the range `1..12`. * `day` is a day-of-month. ### Returns * An integer count of days since the proleptic ISO epoch. ### Examples iex> Calendrical.Roc.date_to_iso_days(115, 1, 1) 739982 # `day_of_era` ```elixir @spec day_of_era(Calendar.year(), Calendar.month(), Calendar.day()) :: {day :: Calendar.day(), era :: Calendar.era()} ``` Calculates the day and era from the given `year`, `month`, and `day`. By default we consider on two eras: before the epoch and on-or-after the epoch. # `day_of_year` ```elixir @spec day_of_year(Calendar.year(), Calendar.month(), Calendar.day()) :: Calendar.day() ``` Calculates the day of the year from the given `year`, `month`, and `day`. # `days_in_month` ```elixir @spec days_in_month(Calendar.month()) :: Calendar.month() | {:ambiguous, Range.t() | [pos_integer()]} | {:error, :undefined} ``` Returns how many days there are in the given month. Must be implemented in derived calendars because we cannot know what the calendar format is. # `days_in_month` ```elixir @spec days_in_month(Calendar.year(), Calendar.month()) :: Calendar.month() @spec days_in_month(year(), month()) :: 28..31 ``` Returns the number of days in the given ROC `year` and `month`. ### Arguments * `year` is any ROC year as an integer. * `month` is a month in the range `1..12`. ### Returns * The number of days in the month (`28..31`). ### Examples iex> Calendrical.Roc.days_in_month(115, 2) 28 iex> Calendrical.Roc.days_in_month(113, 2) 29 # `days_in_week` Returns the number days in a a week. # `days_in_year` ```elixir @spec days_in_year(year()) :: 365..366 ``` Returns the number of days in the given ROC `year`. ### Arguments * `year` is any ROC year as an integer. ### Returns * `365` for an ordinary year or `366` for a leap year. ### Examples iex> Calendrical.Roc.days_in_year(115) 365 iex> Calendrical.Roc.days_in_year(113) 366 # `epoch` # `epoch_day_of_week` # `extended_year` ```elixir @spec extended_year(Calendar.year(), Calendar.month(), Calendar.day()) :: Calendar.year() ``` Returns the extended year as displayed on rendered calendars. # `first_day_of_week` # `gregorian_offset` ```elixir @spec gregorian_offset() :: 1911 ``` Returns the offset (in years) between the ROC era and the proleptic Gregorian calendar. Adding this offset to a ROC year yields the corresponding Gregorian year. ### Returns * The integer `1911`. ### Examples iex> Calendrical.Roc.gregorian_offset() 1911 # `gregorian_year` ```elixir @spec gregorian_year(year()) :: integer() ``` Returns the Gregorian year corresponding to the given ROC year. ### Arguments * `roc_year` is any ROC year as an integer. ### Returns * An integer Gregorian year (1911 more than the input). ### Examples iex> Calendrical.Roc.gregorian_year(115) 2026 # `iso_week_of_year` ```elixir @spec iso_week_of_year(Calendar.year(), Calendar.month(), Calendar.day()) :: {:error, :not_defined} ``` Calculates the ISO week of the year from the given `year`, `month`, and `day`. By default this function always returns `{:error, :not_defined}`. # `last_day_of_week` # `leap_year?` ```elixir @spec leap_year?(year()) :: boolean() ``` Returns whether the given ROC `year` is a leap year. The underlying calendar is proleptic Gregorian, so the leap-year rule applies to the corresponding Gregorian year. ### Arguments * `year` is any ROC year as an integer. ### Returns * `true` if the year contains 366 days; otherwise `false`. ### Examples iex> Calendrical.Roc.leap_year?(113) true iex> Calendrical.Roc.leap_year?(115) false # `month` Returns a `t:Date.Range.t/0` representing a given month of a year. # `month_of_year` ```elixir @spec month_of_year(Calendar.year(), Calendar.month(), Calendar.day()) :: Calendar.month() | {Calendar.month(), Calendrical.leap_month?()} ``` Returns the month of the year from the given `year`, `month`, and `day`. # `months_in_leap_year` Returns the number of months in a leap year. # `months_in_ordinary_year` Returns the number of months in a normal year. # `months_in_year` Returns the number of months in a year, without a year. Returns an integer when every year has the same number of months, or `{:ambiguous, first..last}` for lunisolar calendars whose year length varies (e.g. the Hebrew calendar's 12 or 13 months). # `months_in_year` Returns the number of months in a given `year`. # `naive_datetime_from_iso_days` ```elixir @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 `t:Calendar.iso_days` format to the datetime format specified by this calendar. # `naive_datetime_to_iso_days` ```elixir @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 `t:Calendar.iso_days` format of the specified date. # `periods_in_year` Returns the number of periods in a given `year`. A period corresponds to a month in month-based calendars and a week in week-based calendars. # `plus` Adds an `increment` number of `date_part`s to a `year-month-day`. `date_part` can be `:years`, `:months`, `:weeks` or `:days`. # `quarter` Returns a `t:Date.Range.t/0` representing a given quarter of a year. # `quarter_of_year` ```elixir @spec quarter_of_year(Calendar.year(), Calendar.month(), Calendar.day()) :: Calendrical.quarter() ``` Returns the quarter of the year from the given `year`, `month`, and `day`. # `related_gregorian_year` ```elixir @spec related_gregorian_year(Calendar.year(), Calendar.month(), Calendar.day()) :: Calendar.year() ``` Returns the related Gregorian year as displayed on rendered calendars. Per TR35 this is the Gregorian year in which this calendar's `year` begins, so it is constant for every date of the calendar year. # `roc_year` ```elixir @spec roc_year(integer()) :: year() ``` Returns the ROC year corresponding to the given Gregorian year. ### Arguments * `gregorian_year` is any proleptic Gregorian year as an integer. ### Returns * An integer ROC year (1911 less than the input). ### Examples iex> Calendrical.Roc.roc_year(2026) 115 # `valid_date?` ```elixir @spec valid_date?(year(), month(), day()) :: boolean() ``` Returns whether the given `year`, `month`, and `day` form a valid ROC date. ### Arguments * `year` is any ROC year as an integer. * `month` is a month in the range `1..12`. * `day` is a day-of-month. ### Returns * `true` if the date is valid; otherwise `false`. ### Examples iex> Calendrical.Roc.valid_date?(115, 1, 31) true iex> Calendrical.Roc.valid_date?(115, 2, 29) false # `week` Returns a `t:Date.Range.t/0` representing a given week of a year. # `week_of_month` ```elixir @spec week_of_month(Calendar.year(), Calendar.month(), Calendar.day()) :: {pos_integer(), pos_integer()} | {:error, :not_defined} ``` Calculates the week of the year from the given `year`, `month`, and `day`. By default this function always returns `{:error, :not_defined}`. # `week_of_year` ```elixir @spec week_of_year(Calendar.year(), Calendar.month(), Calendar.day()) :: {:error, :not_defined} ``` Calculates the week of the year from the given `year`, `month`, and `day`. By default this function always returns `{:error, :not_defined}`. # `weeks_in_year` Returns the number of weeks in a given `year`. # `year` Returns a `t:Date.Range.t/0` representing a given year. # `year_of_era` ```elixir @spec year_of_era(Calendar.year()) :: {year :: Calendar.year(), era :: Calendar.era()} ``` Calculates the year and era from the given `year`. # `year_of_era` ```elixir @spec year_of_era(Calendar.year(), Calendar.month(), Calendar.day()) :: {year :: Calendar.year(), era :: Calendar.era()} ``` Calculates the year and era from the given `date`. --- *Consult [api-reference.md](api-reference.md) for complete listing*