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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 Gregorian calendar.
//!
//! ```rust
//! use icu::calendar::{cal::Gregorian, Date};
//!
//! let date_iso = Date::try_new_iso(1970, 1, 2)
//! .expect("Failed to initialize ISO Date instance.");
//! let date_gregorian = Date::new_from_iso(date_iso, Gregorian);
//!
//! assert_eq!(date_gregorian.era_year().year, 1970);
//! assert_eq!(date_gregorian.month().ordinal, 1);
//! assert_eq!(date_gregorian.day_of_month().0, 2);
//! ```
use crate::cal::iso::{Iso, IsoDateInner};
use crate::calendar_arithmetic::ArithmeticDate;
use crate::error::{year_check, DateError};
use crate::{types, Calendar, Date, DateDuration, DateDurationUnit, RangeError};
use calendrical_calculations::rata_die::RataDie;
use tinystr::tinystr;
/// The [(proleptic) Gregorian Calendar](https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar)
///
/// The Gregorian calendar is a solar calendar used by most of the world, with twelve months.
///
/// This type can be used with [`Date`] to represent dates in this calendar.
///
/// # Era codes
///
/// This calendar uses two era codes: `bce` (alias `bc`), and `ce` (alias `ad`), corresponding to the BCE and CE eras.
///
/// # 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 Gregorian;
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq, PartialOrd, Ord)]
/// The inner date type used for representing [`Date`]s of [`Gregorian`]. See [`Date`] and [`Gregorian`] for more details.
pub struct GregorianDateInner(pub(crate) IsoDateInner);
impl crate::cal::scaffold::UnstableSealed for Gregorian {}
impl Calendar for Gregorian {
type DateInner = GregorianDateInner;
type Year = types::EraYear;
fn from_codes(
&self,
era: Option<&str>,
year: i32,
month_code: types::MonthCode,
day: u8,
) -> Result<Self::DateInner, DateError> {
let year = match era {
Some("bce" | "bc") | None => 1 - year_check(year, 1..)?,
Some("ad" | "ce") => year_check(year, 1..)?,
Some(_) => return Err(DateError::UnknownEra),
};
ArithmeticDate::new_from_codes(self, year, month_code, day)
.map(IsoDateInner)
.map(GregorianDateInner)
}
fn from_rata_die(&self, rd: RataDie) -> Self::DateInner {
GregorianDateInner(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) -> GregorianDateInner {
GregorianDateInner(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: DateDuration<Self>) {
Iso.offset_date(&mut date.0, offset.cast_unit())
}
#[allow(clippy::field_reassign_with_default)] // it's more clear this way
fn until(
&self,
date1: &Self::DateInner,
date2: &Self::DateInner,
_calendar2: &Self,
largest_unit: DateDurationUnit,
smallest_unit: DateDurationUnit,
) -> DateDuration<Self> {
Iso.until(&date1.0, &date2.0, &Iso, largest_unit, smallest_unit)
.cast_unit()
}
/// The calendar-specific year represented by `date`
fn year_info(&self, date: &Self::DateInner) -> Self::Year {
let extended_year = self.extended_year(date);
if extended_year > 0 {
types::EraYear {
era: tinystr!(16, "ce"),
era_index: Some(1),
year: extended_year,
ambiguity: match extended_year {
..=999 => types::YearAmbiguity::EraAndCenturyRequired,
1000..=1949 => types::YearAmbiguity::CenturyRequired,
1950..=2049 => types::YearAmbiguity::Unambiguous,
2050.. => types::YearAmbiguity::CenturyRequired,
},
}
} else {
types::EraYear {
era: tinystr!(16, "bce"),
era_index: Some(0),
year: 1_i32.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)
}
/// The calendar-specific month represented by `date`
fn month(&self, date: &Self::DateInner) -> types::MonthInfo {
Iso.month(&date.0)
}
/// The calendar-specific day-of-month represented by `date`
fn day_of_month(&self, date: &Self::DateInner) -> types::DayOfMonth {
Iso.day_of_month(&date.0)
}
/// Information of the day of the year
fn day_of_year(&self, date: &Self::DateInner) -> types::DayOfYear {
date.0 .0.day_of_year()
}
fn debug_name(&self) -> &'static str {
"Gregorian"
}
fn calendar_algorithm(&self) -> Option<crate::preferences::CalendarAlgorithm> {
Some(crate::preferences::CalendarAlgorithm::Gregory)
}
}
impl Date<Gregorian> {
/// Construct a new Gregorian Date.
///
/// Years are specified as ISO years.
///
/// ```rust
/// use icu::calendar::Date;
///
/// // Conversion from ISO to Gregorian
/// let date_gregorian = Date::try_new_gregorian(1970, 1, 2)
/// .expect("Failed to initialize Gregorian Date instance.");
///
/// assert_eq!(date_gregorian.era_year().year, 1970);
/// assert_eq!(date_gregorian.month().ordinal, 1);
/// assert_eq!(date_gregorian.day_of_month().0, 2);
/// ```
pub fn try_new_gregorian(year: i32, month: u8, day: u8) -> Result<Date<Gregorian>, RangeError> {
Date::try_new_iso(year, month, day).map(|d| Date::new_from_iso(d, Gregorian))
}
}
#[cfg(test)]
mod test {
use calendrical_calculations::rata_die::RataDie;
use super::*;
#[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 greg_date_from_rd = Date::from_rata_die(case.rd, Gregorian);
assert_eq!(greg_date_from_rd.era_year().year, case.expected_year,
"Failed year check from RD: {case:?}\nISO: {iso_from_rd:?}\nGreg: {greg_date_from_rd:?}");
assert_eq!(
greg_date_from_rd.era_year().era,
case.expected_era,
"Failed era check from RD: {case:?}\nISO: {iso_from_rd:?}\nGreg: {greg_date_from_rd:?}"
);
assert_eq!(greg_date_from_rd.month().ordinal, case.expected_month,
"Failed month check from RD: {case:?}\nISO: {iso_from_rd:?}\nGreg: {greg_date_from_rd:?}");
assert_eq!(
greg_date_from_rd.day_of_month().0,
case.expected_day,
"Failed day check from RD: {case:?}\nISO: {iso_from_rd:?}\nGreg: {greg_date_from_rd:?}"
);
let iso_date_man: Date<Iso> =
Date::try_new_iso(case.iso_year, case.iso_month, case.iso_day)
.expect("Failed to initialize ISO date for {case:?}");
let greg_date_man: Date<Gregorian> = Date::new_from_iso(iso_date_man, Gregorian);
assert_eq!(iso_from_rd, iso_date_man,
"ISO from RD not equal to ISO generated from manually-input ymd\nCase: {case:?}\nRD: {iso_from_rd:?}\nMan: {iso_date_man:?}");
assert_eq!(greg_date_from_rd, greg_date_man,
"Greg. date from RD not equal to Greg. generated from manually-input ymd\nCase: {case:?}\nRD: {greg_date_from_rd:?}\nMan: {greg_date_man:?}");
}
#[test]
fn test_gregorian_ce() {
// Tests that the Gregorian calendar gives the correct expected
// day, month, and year for positive years (AD/CE/gregory era)
let cases = [
TestCase {
rd: RataDie::new(1),
iso_year: 1,
iso_month: 1,
iso_day: 1,
expected_year: 1,
expected_era: "ce",
expected_month: 1,
expected_day: 1,
},
TestCase {
rd: RataDie::new(181),
iso_year: 1,
iso_month: 6,
iso_day: 30,
expected_year: 1,
expected_era: "ce",
expected_month: 6,
expected_day: 30,
},
TestCase {
rd: RataDie::new(1155),
iso_year: 4,
iso_month: 2,
iso_day: 29,
expected_year: 4,
expected_era: "ce",
expected_month: 2,
expected_day: 29,
},
TestCase {
rd: RataDie::new(1344),
iso_year: 4,
iso_month: 9,
iso_day: 5,
expected_year: 4,
expected_era: "ce",
expected_month: 9,
expected_day: 5,
},
TestCase {
rd: RataDie::new(36219),
iso_year: 100,
iso_month: 3,
iso_day: 1,
expected_year: 100,
expected_era: "ce",
expected_month: 3,
expected_day: 1,
},
];
for case in cases {
check_test_case(case);
}
}
#[test]
fn test_gregorian_bce() {
// Tests that the Gregorian calendar gives the correct expected
// day, month, and year for negative years (BC/BCE era)
let cases = [
TestCase {
rd: RataDie::new(0),
iso_year: 0,
iso_month: 12,
iso_day: 31,
expected_year: 1,
expected_era: "bce",
expected_month: 12,
expected_day: 31,
},
TestCase {
rd: RataDie::new(-365), // This is a leap year
iso_year: 0,
iso_month: 1,
iso_day: 1,
expected_year: 1,
expected_era: "bce",
expected_month: 1,
expected_day: 1,
},
TestCase {
rd: RataDie::new(-366),
iso_year: -1,
iso_month: 12,
iso_day: 31,
expected_year: 2,
expected_era: "bce",
expected_month: 12,
expected_day: 31,
},
TestCase {
rd: RataDie::new(-1461),
iso_year: -4,
iso_month: 12,
iso_day: 31,
expected_year: 5,
expected_era: "bce",
expected_month: 12,
expected_day: 31,
},
TestCase {
rd: RataDie::new(-1826),
iso_year: -4,
iso_month: 1,
iso_day: 1,
expected_year: 5,
expected_era: "bce",
expected_month: 1,
expected_day: 1,
},
];
for case in cases {
check_test_case(case);
}
}
#[test]
fn check_gregorian_directionality() {
// Tests that for a large range of RDs, if a RD
// is less than another, the corresponding YMD should also be less
// than the other, without exception.
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 greg_i = iso_i.to_calendar(Gregorian);
let greg_j = iso_j.to_calendar(Gregorian);
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),
greg_i.cmp(&greg_j),
"Gregorian directionality inconsistent with directionality for i: {i}, j: {j}"
);
}
}
}
}