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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 ISO calendar.
//!
//! ```rust
//! use icu::calendar::{Date, DateTime};
//!
//! // `Date` type
//! let date_iso = Date::try_new_iso_date(1970, 1, 2)
//! .expect("Failed to initialize ISO Date instance.");
//!
//! // `DateTime` type
//! let datetime_iso = DateTime::try_new_iso_datetime(1970, 1, 2, 13, 1, 0)
//! .expect("Failed to initialize ISO DateTime instance.");
//!
//! // `Date` checks
//! assert_eq!(date_iso.year().number, 1970);
//! assert_eq!(date_iso.month().ordinal, 1);
//! assert_eq!(date_iso.day_of_month().0, 2);
//!
//! // `DateTime` type
//! assert_eq!(datetime_iso.date.year().number, 1970);
//! assert_eq!(datetime_iso.date.month().ordinal, 1);
//! assert_eq!(datetime_iso.date.day_of_month().0, 2);
//! assert_eq!(datetime_iso.time.hour.number(), 13);
//! assert_eq!(datetime_iso.time.minute.number(), 1);
//! assert_eq!(datetime_iso.time.second.number(), 0);
//! ```
use crate::any_calendar::AnyCalendarKind;
use crate::calendar_arithmetic::{ArithmeticDate, CalendarArithmetic};
use crate::{types, Calendar, CalendarError, Date, DateDuration, DateDurationUnit, DateTime, Time};
use calendrical_calculations::helpers::{i64_to_saturated_i32, I32CastError};
use calendrical_calculations::rata_die::RataDie;
use tinystr::tinystr;
/// The [ISO Calendar]
///
/// The [ISO Calendar] is a standardized solar calendar with twelve months.
/// It is identical to the Gregorian calendar, except it uses negative years for years before 1 CE,
/// and may have differing formatting data for a given locale.
///
/// This type can be used with [`Date`] or [`DateTime`] to represent dates in this calendar.
///
///
/// # Era codes
///
/// This calendar supports one era, `"default"`
#[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[allow(clippy::exhaustive_structs)] // this type is stable
pub struct Iso;
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq, PartialOrd, Ord)]
/// The inner date type used for representing [`Date`]s of [`Iso`]. See [`Date`] and [`Iso`] for more details.
pub struct IsoDateInner(pub(crate) ArithmeticDate<Iso>);
impl CalendarArithmetic for Iso {
type YearInfo = ();
fn month_days(year: i32, month: u8, _data: ()) -> u8 {
match month {
4 | 6 | 9 | 11 => 30,
2 if Self::is_leap_year(year, ()) => 29,
2 => 28,
1 | 3 | 5 | 7 | 8 | 10 | 12 => 31,
_ => 0,
}
}
fn months_for_every_year(_: i32, _data: ()) -> u8 {
12
}
fn is_leap_year(year: i32, _data: ()) -> bool {
calendrical_calculations::iso::is_leap_year(year)
}
fn last_month_day_in_year(_year: i32, _data: ()) -> (u8, u8) {
(12, 31)
}
fn days_in_provided_year(year: i32, _data: ()) -> u16 {
if Self::is_leap_year(year, ()) {
366
} else {
365
}
}
}
impl Calendar for Iso {
type DateInner = IsoDateInner;
/// Construct a date from era/month codes and fields
fn date_from_codes(
&self,
era: types::Era,
year: i32,
month_code: types::MonthCode,
day: u8,
) -> Result<Self::DateInner, CalendarError> {
if era.0 != tinystr!(16, "default") {
return Err(CalendarError::UnknownEra(era.0, self.debug_name()));
}
ArithmeticDate::new_from_codes(self, year, month_code, day).map(IsoDateInner)
}
fn date_from_iso(&self, iso: Date<Iso>) -> IsoDateInner {
*iso.inner()
}
fn date_to_iso(&self, date: &Self::DateInner) -> Date<Iso> {
Date::from_raw(*date, Iso)
}
fn months_in_year(&self, date: &Self::DateInner) -> u8 {
date.0.months_in_year()
}
fn days_in_year(&self, date: &Self::DateInner) -> u16 {
date.0.days_in_year()
}
fn days_in_month(&self, date: &Self::DateInner) -> u8 {
date.0.days_in_month()
}
fn day_of_week(&self, date: &Self::DateInner) -> types::IsoWeekday {
// For the purposes of the calculation here, Monday is 0, Sunday is 6
// ISO has Monday=1, Sunday=7, which we transform in the last step
// The days of the week are the same every 400 years
// so we normalize to the nearest multiple of 400
let years_since_400 = date.0.year.rem_euclid(400);
debug_assert!(years_since_400 >= 0); // rem_euclid returns positive numbers
let years_since_400 = years_since_400 as u32;
let leap_years_since_400 = years_since_400 / 4 - years_since_400 / 100;
// The number of days to the current year
// Can never cause an overflow because years_since_400 has a maximum value of 399.
let days_to_current_year = 365 * years_since_400 + leap_years_since_400;
// The weekday offset from January 1 this year and January 1 2000
let year_offset = days_to_current_year % 7;
// Corresponding months from
let month_offset = if Self::is_leap_year(date.0.year, ()) {
match date.0.month {
10 => 0,
5 => 1,
2 | 8 => 2,
3 | 11 => 3,
6 => 4,
9 | 12 => 5,
1 | 4 | 7 => 6,
_ => unreachable!(),
}
} else {
match date.0.month {
1 | 10 => 0,
5 => 1,
8 => 2,
2 | 3 | 11 => 3,
6 => 4,
9 | 12 => 5,
4 | 7 => 6,
_ => unreachable!(),
}
};
let january_1_2000 = 5; // Saturday
let day_offset = (january_1_2000 + year_offset + month_offset + date.0.day as u32) % 7;
// We calculated in a zero-indexed fashion, but ISO specifies one-indexed
types::IsoWeekday::from((day_offset + 1) as usize)
}
fn offset_date(&self, date: &mut Self::DateInner, offset: DateDuration<Self>) {
date.0.offset_date(offset, &());
}
#[allow(clippy::field_reassign_with_default)]
fn until(
&self,
date1: &Self::DateInner,
date2: &Self::DateInner,
_calendar2: &Self,
_largest_unit: DateDurationUnit,
_smallest_unit: DateDurationUnit,
) -> DateDuration<Self> {
date1.0.until(date2.0, _largest_unit, _smallest_unit)
}
/// The calendar-specific year represented by `date`
fn year(&self, date: &Self::DateInner) -> types::FormattableYear {
Self::year_as_iso(date.0.year)
}
fn is_in_leap_year(&self, date: &Self::DateInner) -> bool {
Self::is_leap_year(date.0.year, ())
}
/// The calendar-specific month represented by `date`
fn month(&self, date: &Self::DateInner) -> types::FormattableMonth {
date.0.month()
}
/// The calendar-specific day-of-month represented by `date`
fn day_of_month(&self, date: &Self::DateInner) -> types::DayOfMonth {
date.0.day_of_month()
}
fn day_of_year_info(&self, date: &Self::DateInner) -> types::DayOfYearInfo {
let prev_year = date.0.year.saturating_sub(1);
let next_year = date.0.year.saturating_add(1);
types::DayOfYearInfo {
day_of_year: date.0.day_of_year(),
days_in_year: date.0.days_in_year(),
prev_year: Self::year_as_iso(prev_year),
days_in_prev_year: Iso::days_in_year_direct(prev_year),
next_year: Self::year_as_iso(next_year),
}
}
fn debug_name(&self) -> &'static str {
"ISO"
}
fn any_calendar_kind(&self) -> Option<AnyCalendarKind> {
Some(AnyCalendarKind::Iso)
}
}
impl Date<Iso> {
/// Construct a new ISO date from integers.
///
/// ```rust
/// use icu::calendar::Date;
///
/// let date_iso = Date::try_new_iso_date(1970, 1, 2)
/// .expect("Failed to initialize ISO Date instance.");
///
/// assert_eq!(date_iso.year().number, 1970);
/// assert_eq!(date_iso.month().ordinal, 1);
/// assert_eq!(date_iso.day_of_month().0, 2);
/// ```
pub fn try_new_iso_date(year: i32, month: u8, day: u8) -> Result<Date<Iso>, CalendarError> {
ArithmeticDate::new_from_ordinals(year, month, day)
.map(IsoDateInner)
.map(|inner| Date::from_raw(inner, Iso))
}
/// Constructs an ISO date representing the UNIX epoch on January 1, 1970.
pub fn unix_epoch() -> Self {
Date::from_raw(IsoDateInner(ArithmeticDate::new_unchecked(1970, 1, 1)), Iso)
}
}
impl DateTime<Iso> {
/// Construct a new ISO datetime from integers.
///
/// ```rust
/// use icu::calendar::DateTime;
///
/// let datetime_iso = DateTime::try_new_iso_datetime(1970, 1, 2, 13, 1, 0)
/// .expect("Failed to initialize ISO DateTime instance.");
///
/// assert_eq!(datetime_iso.date.year().number, 1970);
/// assert_eq!(datetime_iso.date.month().ordinal, 1);
/// assert_eq!(datetime_iso.date.day_of_month().0, 2);
/// assert_eq!(datetime_iso.time.hour.number(), 13);
/// assert_eq!(datetime_iso.time.minute.number(), 1);
/// assert_eq!(datetime_iso.time.second.number(), 0);
/// ```
pub fn try_new_iso_datetime(
year: i32,
month: u8,
day: u8,
hour: u8,
minute: u8,
second: u8,
) -> Result<DateTime<Iso>, CalendarError> {
Ok(DateTime {
date: Date::try_new_iso_date(year, month, day)?,
time: Time::try_new(hour, minute, second, 0)?,
})
}
/// Constructs an ISO datetime representing the UNIX epoch on January 1, 1970
/// at midnight.
pub fn local_unix_epoch() -> Self {
DateTime {
date: Date::unix_epoch(),
time: Time::midnight(),
}
}
/// Minute count representation of calendars starting from 00:00:00 on Jan 1st, 1970.
///
/// ```rust
/// use icu::calendar::DateTime;
///
/// let today = DateTime::try_new_iso_datetime(2020, 2, 29, 0, 0, 0).unwrap();
///
/// assert_eq!(today.minutes_since_local_unix_epoch(), 26382240);
/// assert_eq!(
/// DateTime::from_minutes_since_local_unix_epoch(26382240),
/// today
/// );
///
/// let today = DateTime::try_new_iso_datetime(1970, 1, 1, 0, 0, 0).unwrap();
///
/// assert_eq!(today.minutes_since_local_unix_epoch(), 0);
/// assert_eq!(DateTime::from_minutes_since_local_unix_epoch(0), today);
/// ```
pub fn minutes_since_local_unix_epoch(&self) -> i32 {
let minutes_a_hour = 60;
let hours_a_day = 24;
let minutes_a_day = minutes_a_hour * hours_a_day;
let unix_epoch = Iso::fixed_from_iso(Date::unix_epoch().inner);
let result = (Iso::fixed_from_iso(*self.date.inner()) - unix_epoch) * minutes_a_day
+ i64::from(self.time.hour.number()) * minutes_a_hour
+ i64::from(self.time.minute.number());
i64_to_saturated_i32(result)
}
/// Convert minute count since 00:00:00 on Jan 1st, 1970 to ISO Date.
///
/// # Examples
///
/// ```rust
/// use icu::calendar::DateTime;
///
/// // After Unix Epoch
/// let today = DateTime::try_new_iso_datetime(2020, 2, 29, 0, 0, 0).unwrap();
///
/// assert_eq!(today.minutes_since_local_unix_epoch(), 26382240);
/// assert_eq!(
/// DateTime::from_minutes_since_local_unix_epoch(26382240),
/// today
/// );
///
/// // Unix Epoch
/// let today = DateTime::try_new_iso_datetime(1970, 1, 1, 0, 0, 0).unwrap();
///
/// assert_eq!(today.minutes_since_local_unix_epoch(), 0);
/// assert_eq!(DateTime::from_minutes_since_local_unix_epoch(0), today);
///
/// // Before Unix Epoch
/// let today = DateTime::try_new_iso_datetime(1967, 4, 6, 20, 40, 0).unwrap();
///
/// assert_eq!(today.minutes_since_local_unix_epoch(), -1440200);
/// assert_eq!(
/// DateTime::from_minutes_since_local_unix_epoch(-1440200),
/// today
/// );
/// ```
pub fn from_minutes_since_local_unix_epoch(minute: i32) -> DateTime<Iso> {
let (time, extra_days) = Time::from_minute_with_remainder_days(minute);
let unix_epoch = Date::unix_epoch();
let unix_epoch_days = Iso::fixed_from_iso(unix_epoch.inner);
let date = Iso::iso_from_fixed(unix_epoch_days + extra_days as i64);
DateTime { date, time }
}
}
impl Iso {
/// Construct a new ISO Calendar
pub fn new() -> Self {
Self
}
/// Count the number of days in a given month/year combo
fn days_in_month(year: i32, month: u8) -> u8 {
match month {
4 | 6 | 9 | 11 => 30,
2 if Self::is_leap_year(year, ()) => 29,
2 => 28,
_ => 31,
}
}
pub(crate) fn days_in_year_direct(year: i32) -> u16 {
if Self::is_leap_year(year, ()) {
366
} else {
365
}
}
// Fixed is day count representation of calendars starting from Jan 1st of year 1.
// The fixed calculations algorithms are from the Calendrical Calculations book.
pub(crate) fn fixed_from_iso(date: IsoDateInner) -> RataDie {
calendrical_calculations::iso::fixed_from_iso(date.0.year, date.0.month, date.0.day)
}
pub(crate) fn iso_from_year_day(year: i32, year_day: u16) -> Date<Iso> {
let mut month = 1;
let mut day = year_day as i32;
while month <= 12 {
let month_days = Self::days_in_month(year, month) as i32;
if day <= month_days {
break;
} else {
debug_assert!(month < 12); // don't try going to month 13
day -= month_days;
month += 1;
}
}
let day = day as u8; // day <= month_days < u8::MAX
#[allow(clippy::unwrap_used)] // month in 1..=12, day <= month_days
Date::try_new_iso_date(year, month, day).unwrap()
}
pub(crate) fn iso_from_fixed(date: RataDie) -> Date<Iso> {
let (year, month, day) = match calendrical_calculations::iso::iso_from_fixed(date) {
Err(I32CastError::BelowMin) => {
return Date::from_raw(IsoDateInner(ArithmeticDate::min_date()), Iso)
}
Err(I32CastError::AboveMax) => {
return Date::from_raw(IsoDateInner(ArithmeticDate::max_date()), Iso)
}
Ok(ymd) => ymd,
};
#[allow(clippy::unwrap_used)] // valid day and month
Date::try_new_iso_date(year, month, day).unwrap()
}
pub(crate) fn day_of_year(date: IsoDateInner) -> u16 {
// Cumulatively how much are dates in each month
// offset from "30 days in each month" (in non leap years)
let month_offset = [0, 1, -1, 0, 0, 1, 1, 2, 3, 3, 4, 4];
#[allow(clippy::indexing_slicing)] // date.0.month in 1..=12
let mut offset = month_offset[date.0.month as usize - 1];
if Self::is_leap_year(date.0.year, ()) && date.0.month > 2 {
// Months after February in a leap year are offset by one less
offset += 1;
}
let prev_month_days = (30 * (date.0.month as i32 - 1) + offset) as u16;
prev_month_days + date.0.day as u16
}
/// Wrap the year in the appropriate era code
fn year_as_iso(year: i32) -> types::FormattableYear {
types::FormattableYear {
era: types::Era(tinystr!(16, "default")),
number: year,
cyclic: None,
related_iso: None,
}
}
}
impl IsoDateInner {
pub(crate) fn jan_1(year: i32) -> Self {
Self(ArithmeticDate::new_unchecked(year, 1, 1))
}
pub(crate) fn dec_31(year: i32) -> Self {
Self(ArithmeticDate::new_unchecked(year, 12, 1))
}
}
impl From<&'_ IsoDateInner> for crate::provider::EraStartDate {
fn from(other: &'_ IsoDateInner) -> Self {
Self {
year: other.0.year,
month: other.0.month,
day: other.0.day,
}
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::types::IsoWeekday;
#[test]
fn iso_overflow() {
#[derive(Debug)]
struct TestCase {
year: i32,
month: u8,
day: u8,
fixed: RataDie,
saturating: bool,
}
// Calculates the max possible year representable using i32::MAX as the fixed date
let max_year = Iso::iso_from_fixed(RataDie::new(i32::MAX as i64))
.year()
.number;
// Calculates the minimum possible year representable using i32::MIN as the fixed date
// *Cannot be tested yet due to hard coded date not being available yet (see line 436)
let min_year = -5879610;
let cases = [
TestCase {
// Earliest date that can be represented before causing a minimum overflow
year: min_year,
month: 6,
day: 22,
fixed: RataDie::new(i32::MIN as i64),
saturating: false,
},
TestCase {
year: min_year,
month: 6,
day: 23,
fixed: RataDie::new(i32::MIN as i64 + 1),
saturating: false,
},
TestCase {
year: min_year,
month: 6,
day: 21,
fixed: RataDie::new(i32::MIN as i64 - 1),
saturating: false,
},
TestCase {
year: min_year,
month: 12,
day: 31,
fixed: RataDie::new(-2147483456),
saturating: false,
},
TestCase {
year: min_year + 1,
month: 1,
day: 1,
fixed: RataDie::new(-2147483455),
saturating: false,
},
TestCase {
year: max_year,
month: 6,
day: 11,
fixed: RataDie::new(i32::MAX as i64 - 30),
saturating: false,
},
TestCase {
year: max_year,
month: 7,
day: 9,
fixed: RataDie::new(i32::MAX as i64 - 2),
saturating: false,
},
TestCase {
year: max_year,
month: 7,
day: 10,
fixed: RataDie::new(i32::MAX as i64 - 1),
saturating: false,
},
TestCase {
// Latest date that can be represented before causing a maximum overflow
year: max_year,
month: 7,
day: 11,
fixed: RataDie::new(i32::MAX as i64),
saturating: false,
},
TestCase {
year: max_year,
month: 7,
day: 12,
fixed: RataDie::new(i32::MAX as i64 + 1),
saturating: false,
},
TestCase {
year: i32::MIN,
month: 1,
day: 2,
fixed: RataDie::new(-784352296669),
saturating: false,
},
TestCase {
year: i32::MIN,
month: 1,
day: 1,
fixed: RataDie::new(-784352296670),
saturating: false,
},
TestCase {
year: i32::MIN,
month: 1,
day: 1,
fixed: RataDie::new(-784352296671),
saturating: true,
},
TestCase {
year: i32::MAX,
month: 12,
day: 30,
fixed: RataDie::new(784352295938),
saturating: false,
},
TestCase {
year: i32::MAX,
month: 12,
day: 31,
fixed: RataDie::new(784352295939),
saturating: false,
},
TestCase {
year: i32::MAX,
month: 12,
day: 31,
fixed: RataDie::new(784352295940),
saturating: true,
},
];
for case in cases {
let date = Date::try_new_iso_date(case.year, case.month, case.day).unwrap();
if !case.saturating {
assert_eq!(Iso::fixed_from_iso(date.inner), case.fixed, "{case:?}");
}
assert_eq!(Iso::iso_from_fixed(case.fixed), date, "{case:?}");
}
}
// Calculates the minimum possible year representable using a large negative fixed date
#[test]
fn min_year() {
assert_eq!(
Iso::iso_from_fixed(RataDie::big_negative()).year().number,
i32::MIN
);
}
#[test]
fn test_day_of_week() {
// June 23, 2021 is a Wednesday
assert_eq!(
Date::try_new_iso_date(2021, 6, 23).unwrap().day_of_week(),
IsoWeekday::Wednesday,
);
// Feb 2, 1983 was a Wednesday
assert_eq!(
Date::try_new_iso_date(1983, 2, 2).unwrap().day_of_week(),
IsoWeekday::Wednesday,
);
// Jan 21, 2021 was a Tuesday
assert_eq!(
Date::try_new_iso_date(2020, 1, 21).unwrap().day_of_week(),
IsoWeekday::Tuesday,
);
}
#[test]
fn test_day_of_year() {
// June 23, 2021 was day 174
assert_eq!(
Date::try_new_iso_date(2021, 6, 23)
.unwrap()
.day_of_year_info()
.day_of_year,
174,
);
// June 23, 2020 was day 175
assert_eq!(
Date::try_new_iso_date(2020, 6, 23)
.unwrap()
.day_of_year_info()
.day_of_year,
175,
);
// Feb 2, 1983 was a Wednesday
assert_eq!(
Date::try_new_iso_date(1983, 2, 2)
.unwrap()
.day_of_year_info()
.day_of_year,
33,
);
}
fn simple_subtract(a: &Date<Iso>, b: &Date<Iso>) -> DateDuration<Iso> {
let a = a.inner();
let b = b.inner();
DateDuration::new(
a.0.year - b.0.year,
a.0.month as i32 - b.0.month as i32,
0,
a.0.day as i32 - b.0.day as i32,
)
}
#[test]
fn test_offset() {
let today = Date::try_new_iso_date(2021, 6, 23).unwrap();
let today_plus_5000 = Date::try_new_iso_date(2035, 3, 2).unwrap();
let offset = today.added(DateDuration::new(0, 0, 0, 5000));
assert_eq!(offset, today_plus_5000);
let offset = today.added(simple_subtract(&today_plus_5000, &today));
assert_eq!(offset, today_plus_5000);
let today = Date::try_new_iso_date(2021, 6, 23).unwrap();
let today_minus_5000 = Date::try_new_iso_date(2007, 10, 15).unwrap();
let offset = today.added(DateDuration::new(0, 0, 0, -5000));
assert_eq!(offset, today_minus_5000);
let offset = today.added(simple_subtract(&today_minus_5000, &today));
assert_eq!(offset, today_minus_5000);
}
#[test]
fn test_offset_at_month_boundary() {
let today = Date::try_new_iso_date(2020, 2, 28).unwrap();
let today_plus_2 = Date::try_new_iso_date(2020, 3, 1).unwrap();
let offset = today.added(DateDuration::new(0, 0, 0, 2));
assert_eq!(offset, today_plus_2);
let today = Date::try_new_iso_date(2020, 2, 28).unwrap();
let today_plus_3 = Date::try_new_iso_date(2020, 3, 2).unwrap();
let offset = today.added(DateDuration::new(0, 0, 0, 3));
assert_eq!(offset, today_plus_3);
let today = Date::try_new_iso_date(2020, 2, 28).unwrap();
let today_plus_1 = Date::try_new_iso_date(2020, 2, 29).unwrap();
let offset = today.added(DateDuration::new(0, 0, 0, 1));
assert_eq!(offset, today_plus_1);
let today = Date::try_new_iso_date(2019, 2, 28).unwrap();
let today_plus_2 = Date::try_new_iso_date(2019, 3, 2).unwrap();
let offset = today.added(DateDuration::new(0, 0, 0, 2));
assert_eq!(offset, today_plus_2);
let today = Date::try_new_iso_date(2019, 2, 28).unwrap();
let today_plus_1 = Date::try_new_iso_date(2019, 3, 1).unwrap();
let offset = today.added(DateDuration::new(0, 0, 0, 1));
assert_eq!(offset, today_plus_1);
let today = Date::try_new_iso_date(2020, 3, 1).unwrap();
let today_minus_1 = Date::try_new_iso_date(2020, 2, 29).unwrap();
let offset = today.added(DateDuration::new(0, 0, 0, -1));
assert_eq!(offset, today_minus_1);
}
#[test]
fn test_offset_handles_negative_month_offset() {
let today = Date::try_new_iso_date(2020, 3, 1).unwrap();
let today_minus_2_months = Date::try_new_iso_date(2020, 1, 1).unwrap();
let offset = today.added(DateDuration::new(0, -2, 0, 0));
assert_eq!(offset, today_minus_2_months);
let today = Date::try_new_iso_date(2020, 3, 1).unwrap();
let today_minus_4_months = Date::try_new_iso_date(2019, 11, 1).unwrap();
let offset = today.added(DateDuration::new(0, -4, 0, 0));
assert_eq!(offset, today_minus_4_months);
let today = Date::try_new_iso_date(2020, 3, 1).unwrap();
let today_minus_24_months = Date::try_new_iso_date(2018, 3, 1).unwrap();
let offset = today.added(DateDuration::new(0, -24, 0, 0));
assert_eq!(offset, today_minus_24_months);
let today = Date::try_new_iso_date(2020, 3, 1).unwrap();
let today_minus_27_months = Date::try_new_iso_date(2017, 12, 1).unwrap();
let offset = today.added(DateDuration::new(0, -27, 0, 0));
assert_eq!(offset, today_minus_27_months);
}
#[test]
fn test_offset_handles_out_of_bound_month_offset() {
let today = Date::try_new_iso_date(2021, 1, 31).unwrap();
// since 2021/02/31 isn't a valid date, `offset_date` auto-adjusts by adding 3 days to 2021/02/28
let today_plus_1_month = Date::try_new_iso_date(2021, 3, 3).unwrap();
let offset = today.added(DateDuration::new(0, 1, 0, 0));
assert_eq!(offset, today_plus_1_month);
let today = Date::try_new_iso_date(2021, 1, 31).unwrap();
// since 2021/02/31 isn't a valid date, `offset_date` auto-adjusts by adding 3 days to 2021/02/28
let today_plus_1_month_1_day = Date::try_new_iso_date(2021, 3, 4).unwrap();
let offset = today.added(DateDuration::new(0, 1, 0, 1));
assert_eq!(offset, today_plus_1_month_1_day);
}
#[test]
fn test_iso_to_from_fixed() {
// Reminder: ISO year 0 is Gregorian year 1 BCE.
// Year 0 is a leap year due to the 400-year rule.
fn check(fixed: i64, year: i32, month: u8, day: u8) {
let fixed = RataDie::new(fixed);
assert_eq!(
Iso::iso_from_fixed(fixed),
Date::try_new_iso_date(year, month, day).unwrap(),
"fixed: {fixed:?}"
);
}
check(-1828, -5, 12, 30);
check(-1827, -5, 12, 31); // leap year
check(-1826, -4, 1, 1);
check(-1462, -4, 12, 30);
check(-1461, -4, 12, 31);
check(-1460, -3, 1, 1);
check(-1459, -3, 1, 2);
check(-732, -2, 12, 30);
check(-731, -2, 12, 31);
check(-730, -1, 1, 1);
check(-367, -1, 12, 30);
check(-366, -1, 12, 31);
check(-365, 0, 1, 1); // leap year
check(-364, 0, 1, 2);
check(-1, 0, 12, 30);
check(0, 0, 12, 31);
check(1, 1, 1, 1);
check(2, 1, 1, 2);
check(364, 1, 12, 30);
check(365, 1, 12, 31);
check(366, 2, 1, 1);
check(1459, 4, 12, 29);
check(1460, 4, 12, 30);
check(1461, 4, 12, 31); // leap year
check(1462, 5, 1, 1);
}
#[test]
fn test_from_minutes_since_local_unix_epoch() {
fn check(minutes: i32, year: i32, month: u8, day: u8, hour: u8, minute: u8) {
let today = DateTime::try_new_iso_datetime(year, month, day, hour, minute, 0).unwrap();
assert_eq!(today.minutes_since_local_unix_epoch(), minutes);
assert_eq!(
DateTime::from_minutes_since_local_unix_epoch(minutes),
today
);
}
check(-1441, 1969, 12, 30, 23, 59);
check(-1440, 1969, 12, 31, 0, 0);
check(-1439, 1969, 12, 31, 0, 1);
check(-2879, 1969, 12, 30, 0, 1);
}
}