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// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
//! This module contains types and implementations for the Republic of China calendar.
//!
//! ```rust
//! use icu::calendar::{cal::Roc, Date};
//!
//! let date_iso = Date::try_new_iso(1970, 1, 2)
//! .expect("Failed to initialize ISO Date instance.");
//! let date_roc = Date::new_from_iso(date_iso, Roc);
//!
//! assert_eq!(date_roc.era_year().year, 59);
//! assert_eq!(date_roc.month().ordinal, 1);
//! assert_eq!(date_roc.day_of_month().0, 2);
//! ```
use crate::error::year_check;
use crate::{
cal::iso::IsoDateInner, calendar_arithmetic::ArithmeticDate, error::DateError, types, Calendar,
Date, Iso, RangeError,
};
use calendrical_calculations::rata_die::RataDie;
use tinystr::tinystr;
/// Year of the beginning of the Taiwanese (ROC/Minguo) calendar.
/// 1912 ISO = ROC 1
const ROC_ERA_OFFSET: i32 = 1911;
///
/// The ROC calendar is a solar calendar used in Taiwan and Penghu, as well as by overseas diaspora from
/// those locations. Months and days are identical to the [`Gregorian`](super::Gregorian) calendar, while years are counted
/// with 1912, the year of the establishment of the Republic of China, as year 1 of the ROC/Minguo/民国/民國 era.
///
/// The ROC calendar should not be confused with the Chinese traditional lunar calendar
/// (see [`Chinese`](crate::cal::Chinese)).
///
/// # Era codes
///
/// This calendar uses two era codes: `roc`, corresponding to years in the 民國 era (CE year 1912 and
/// after), and `broc`, corresponding to years before the 民國 era (CE year 1911 and before).
///
///
/// # Month codes
///
/// This calendar supports 12 solar month codes (`"M01" - "M12"`)
#[derive(Copy, Clone, Debug, Default)]
#[allow(clippy::exhaustive_structs)] // this type is stable
pub struct Roc;
/// The inner date type used for representing [`Date`]s of [`Roc`]. See [`Date`] and [`Roc`] for more info.
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq, PartialOrd, Ord)]
pub struct RocDateInner(IsoDateInner);
impl crate::cal::scaffold::UnstableSealed for Roc {}
impl Calendar for Roc {
type DateInner = RocDateInner;
type Year = types::EraYear;
fn from_codes(
&self,
era: Option<&str>,
year: i32,
month_code: crate::types::MonthCode,
day: u8,
) -> Result<Self::DateInner, DateError> {
let year = match era {
Some("roc") | None => ROC_ERA_OFFSET + year_check(year, 1..)?,
Some("broc") => ROC_ERA_OFFSET + 1 - year_check(year, 1..)?,
Some(_) => return Err(DateError::UnknownEra),
};
ArithmeticDate::new_from_codes(self, year, month_code, day)
.map(IsoDateInner)
.map(RocDateInner)
}
fn from_rata_die(&self, rd: RataDie) -> Self::DateInner {
RocDateInner(Iso.from_rata_die(rd))
}
fn to_rata_die(&self, date: &Self::DateInner) -> RataDie {
Iso.to_rata_die(&date.0)
}
fn from_iso(&self, iso: IsoDateInner) -> Self::DateInner {
RocDateInner(iso)
}
fn to_iso(&self, date: &Self::DateInner) -> IsoDateInner {
date.0
}
fn months_in_year(&self, date: &Self::DateInner) -> u8 {
Iso.months_in_year(&date.0)
}
fn days_in_year(&self, date: &Self::DateInner) -> u16 {
Iso.days_in_year(&date.0)
}
fn days_in_month(&self, date: &Self::DateInner) -> u8 {
Iso.days_in_month(&date.0)
}
fn offset_date(&self, date: &mut Self::DateInner, offset: crate::DateDuration<Self>) {
Iso.offset_date(&mut date.0, offset.cast_unit())
}
fn until(
&self,
date1: &Self::DateInner,
date2: &Self::DateInner,
_calendar2: &Self,
largest_unit: crate::DateDurationUnit,
smallest_unit: crate::DateDurationUnit,
) -> crate::DateDuration<Self> {
Iso.until(&date1.0, &date2.0, &Iso, largest_unit, smallest_unit)
.cast_unit()
}
fn debug_name(&self) -> &'static str {
"ROC"
}
fn year_info(&self, date: &Self::DateInner) -> Self::Year {
let extended_year = self.extended_year(date);
if extended_year > ROC_ERA_OFFSET {
types::EraYear {
era: tinystr!(16, "roc"),
era_index: Some(1),
year: extended_year.saturating_sub(ROC_ERA_OFFSET),
ambiguity: types::YearAmbiguity::CenturyRequired,
}
} else {
types::EraYear {
era: tinystr!(16, "broc"),
era_index: Some(0),
year: (ROC_ERA_OFFSET + 1).saturating_sub(extended_year),
ambiguity: types::YearAmbiguity::EraAndCenturyRequired,
}
}
}
fn extended_year(&self, date: &Self::DateInner) -> i32 {
Iso.extended_year(&date.0)
}
fn is_in_leap_year(&self, date: &Self::DateInner) -> bool {
Iso.is_in_leap_year(&date.0)
}
fn month(&self, date: &Self::DateInner) -> crate::types::MonthInfo {
Iso.month(&date.0)
}
fn day_of_month(&self, date: &Self::DateInner) -> crate::types::DayOfMonth {
Iso.day_of_month(&date.0)
}
fn day_of_year(&self, date: &Self::DateInner) -> types::DayOfYear {
Iso.day_of_year(&date.0)
}
fn calendar_algorithm(&self) -> Option<crate::preferences::CalendarAlgorithm> {
Some(crate::preferences::CalendarAlgorithm::Roc)
}
}
impl Date<Roc> {
/// Construct a new Republic of China calendar Date.
///
/// Years are specified in the "roc" era. This function accepts an extended year in that era, so dates
/// before Minguo are negative and year 0 is 1 Before Minguo. To specify dates using explicit era
/// codes, use [`Date::try_new_from_codes()`].
///
/// ```rust
/// use icu::calendar::Date;
/// use icu::calendar::cal::Gregorian;
/// use tinystr::tinystr;
///
/// // Create a new ROC Date
/// let date_roc = Date::try_new_roc(1, 2, 3)
/// .expect("Failed to initialize ROC Date instance.");
///
/// assert_eq!(date_roc.era_year().era, tinystr!(16, "roc"));
/// assert_eq!(date_roc.era_year().year, 1, "ROC year check failed!");
/// assert_eq!(date_roc.month().ordinal, 2, "ROC month check failed!");
/// assert_eq!(date_roc.day_of_month().0, 3, "ROC day of month check failed!");
///
/// // Convert to an equivalent Gregorian date
/// let date_gregorian = date_roc.to_calendar(Gregorian);
///
/// assert_eq!(date_gregorian.era_year().year, 1912, "Gregorian from ROC year check failed!");
/// assert_eq!(date_gregorian.month().ordinal, 2, "Gregorian from ROC month check failed!");
/// assert_eq!(date_gregorian.day_of_month().0, 3, "Gregorian from ROC day of month check failed!");
pub fn try_new_roc(year: i32, month: u8, day: u8) -> Result<Date<Roc>, RangeError> {
let iso_year = year.saturating_add(ROC_ERA_OFFSET);
Date::try_new_iso(iso_year, month, day).map(|d| Date::new_from_iso(d, Roc))
}
}
#[cfg(test)]
mod test {
use super::*;
use calendrical_calculations::rata_die::RataDie;
#[derive(Debug)]
struct TestCase {
rd: RataDie,
iso_year: i32,
iso_month: u8,
iso_day: u8,
expected_year: i32,
expected_era: &'static str,
expected_month: u8,
expected_day: u8,
}
fn check_test_case(case: TestCase) {
let iso_from_rd = Date::from_rata_die(case.rd, Iso);
let roc_from_rd = Date::from_rata_die(case.rd, Roc);
assert_eq!(
roc_from_rd.era_year().year,
case.expected_year,
"Failed year check from RD: {case:?}\nISO: {iso_from_rd:?}\nROC: {roc_from_rd:?}"
);
assert_eq!(
roc_from_rd.era_year().era,
case.expected_era,
"Failed era check from RD: {case:?}\nISO: {iso_from_rd:?}\nROC: {roc_from_rd:?}"
);
assert_eq!(
roc_from_rd.month().ordinal,
case.expected_month,
"Failed month check from RD: {case:?}\nISO: {iso_from_rd:?}\nROC: {roc_from_rd:?}"
);
assert_eq!(roc_from_rd.day_of_month().0, case.expected_day,
"Failed day_of_month check from RD: {case:?}\nISO: {iso_from_rd:?}\nROC: {roc_from_rd:?}");
let iso_from_case = Date::try_new_iso(case.iso_year, case.iso_month, case.iso_day)
.expect("Failed to initialize ISO date for {case:?}");
let roc_from_case = Date::new_from_iso(iso_from_case, Roc);
assert_eq!(iso_from_rd, iso_from_case,
"ISO from RD not equal to ISO generated from manually-input ymd\nCase: {case:?}\nRD: {iso_from_rd:?}\nManual: {iso_from_case:?}");
assert_eq!(roc_from_rd, roc_from_case,
"ROC date from RD not equal to ROC generated from manually-input ymd\nCase: {case:?}\nRD: {roc_from_rd:?}\nManual: {roc_from_case:?}");
}
#[test]
fn test_roc_current_era() {
// Tests that the ROC calendar gives the correct expected day, month, and year for years >= 1912
// (years in the ROC/minguo era)
//
// Jan 1. 1912 CE = RD 697978
let cases = [
TestCase {
rd: RataDie::new(697978),
iso_year: 1912,
iso_month: 1,
iso_day: 1,
expected_year: 1,
expected_era: "roc",
expected_month: 1,
expected_day: 1,
},
TestCase {
rd: RataDie::new(698037),
iso_year: 1912,
iso_month: 2,
iso_day: 29,
expected_year: 1,
expected_era: "roc",
expected_month: 2,
expected_day: 29,
},
TestCase {
rd: RataDie::new(698524),
iso_year: 1913,
iso_month: 6,
iso_day: 30,
expected_year: 2,
expected_era: "roc",
expected_month: 6,
expected_day: 30,
},
TestCase {
rd: RataDie::new(738714),
iso_year: 2023,
iso_month: 7,
iso_day: 13,
expected_year: 112,
expected_era: "roc",
expected_month: 7,
expected_day: 13,
},
];
for case in cases {
check_test_case(case);
}
}
#[test]
fn test_roc_prior_era() {
// Tests that the ROC calendar gives the correct expected day, month, and year for years <= 1911
// (years in the ROC/minguo era)
//
// Jan 1. 1912 CE = RD 697978
let cases = [
TestCase {
rd: RataDie::new(697977),
iso_year: 1911,
iso_month: 12,
iso_day: 31,
expected_year: 1,
expected_era: "broc",
expected_month: 12,
expected_day: 31,
},
TestCase {
rd: RataDie::new(697613),
iso_year: 1911,
iso_month: 1,
iso_day: 1,
expected_year: 1,
expected_era: "broc",
expected_month: 1,
expected_day: 1,
},
TestCase {
rd: RataDie::new(697612),
iso_year: 1910,
iso_month: 12,
iso_day: 31,
expected_year: 2,
expected_era: "broc",
expected_month: 12,
expected_day: 31,
},
TestCase {
rd: RataDie::new(696576),
iso_year: 1908,
iso_month: 2,
iso_day: 29,
expected_year: 4,
expected_era: "broc",
expected_month: 2,
expected_day: 29,
},
TestCase {
rd: RataDie::new(1),
iso_year: 1,
iso_month: 1,
iso_day: 1,
expected_year: 1911,
expected_era: "broc",
expected_month: 1,
expected_day: 1,
},
TestCase {
rd: RataDie::new(0),
iso_year: 0,
iso_month: 12,
iso_day: 31,
expected_year: 1912,
expected_era: "broc",
expected_month: 12,
expected_day: 31,
},
];
for case in cases {
check_test_case(case);
}
}
#[test]
fn test_roc_directionality_near_epoch() {
// Tests that for a large range of RDs near the beginning of the minguo era (CE 1912),
// the comparison between those two RDs should be equal to the comparison between their
// corresponding YMD.
let rd_epoch_start = 697978;
for i in (rd_epoch_start - 100)..=(rd_epoch_start + 100) {
for j in (rd_epoch_start - 100)..=(rd_epoch_start + 100) {
let iso_i = Date::from_rata_die(RataDie::new(i), Iso);
let iso_j = Date::from_rata_die(RataDie::new(j), Iso);
let roc_i = Date::from_rata_die(RataDie::new(i), Roc);
let roc_j = Date::from_rata_die(RataDie::new(j), Roc);
assert_eq!(
i.cmp(&j),
iso_i.cmp(&iso_j),
"ISO directionality inconsistent with directionality for i: {i}, j: {j}"
);
assert_eq!(
i.cmp(&j),
roc_i.cmp(&roc_j),
"ROC directionality inconsistent with directionality for i: {i}, j: {j}"
);
}
}
}
#[test]
fn test_roc_directionality_near_rd_zero() {
// Same as `test_directionality_near_epoch`, but with a focus around RD 0
for i in -100..=100 {
for j in -100..100 {
let iso_i = Date::from_rata_die(RataDie::new(i), Iso);
let iso_j = Date::from_rata_die(RataDie::new(j), Iso);
let roc_i = Date::from_rata_die(RataDie::new(i), Roc);
let roc_j = Date::from_rata_die(RataDie::new(j), Roc);
assert_eq!(
i.cmp(&j),
iso_i.cmp(&iso_j),
"ISO directionality inconsistent with directionality for i: {i}, j: {j}"
);
assert_eq!(
i.cmp(&j),
roc_i.cmp(&roc_j),
"ROC directionality inconsistent with directionality for i: {i}, j: {j}"
);
}
}
}
}