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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
use crate::{types, Calendar, CalendarError, DateDuration, DateDurationUnit};
use core::cmp::Ordering;
use core::convert::TryInto;
use core::fmt::Debug;
use core::hash::{Hash, Hasher};
use core::marker::PhantomData;
use tinystr::tinystr;
// Note: The Ord/PartialOrd impls can be derived because the fields are in the correct order.
#[derive(Debug)]
#[allow(clippy::exhaustive_structs)] // this type is stable
pub(crate) struct ArithmeticDate<C: CalendarArithmetic> {
pub year: i32,
/// 1-based month of year
pub month: u8,
/// 1-based day of month
pub day: u8,
/// Invariant: MUST be updated to match the info for `year` whenever `year` is updated or set.
pub year_info: C::YearInfo,
marker: PhantomData<C>,
}
// Manual impls since the derive will introduce a C: Trait bound
// and many of these impls can ignore the year_info field
impl<C: CalendarArithmetic> Copy for ArithmeticDate<C> {}
impl<C: CalendarArithmetic> Clone for ArithmeticDate<C> {
fn clone(&self) -> Self {
*self
}
}
impl<C: CalendarArithmetic> PartialEq for ArithmeticDate<C> {
fn eq(&self, other: &Self) -> bool {
self.year == other.year && self.month == other.month && self.day == other.day
}
}
impl<C: CalendarArithmetic> Eq for ArithmeticDate<C> {}
impl<C: CalendarArithmetic> Ord for ArithmeticDate<C> {
fn cmp(&self, other: &Self) -> Ordering {
self.year
.cmp(&other.year)
.then(self.month.cmp(&other.month))
.then(self.day.cmp(&other.day))
}
}
impl<C: CalendarArithmetic> PartialOrd for ArithmeticDate<C> {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl<C: CalendarArithmetic> Hash for ArithmeticDate<C> {
fn hash<H>(&self, state: &mut H)
where
H: Hasher,
{
self.year.hash(state);
self.month.hash(state);
self.day.hash(state);
}
}
/// Maximum number of iterations when iterating through the days of a month; can be increased if necessary
#[allow(dead_code)] // TODO: Remove dead code tag after use
pub(crate) const MAX_ITERS_FOR_DAYS_OF_MONTH: u8 = 33;
pub(crate) trait CalendarArithmetic: Calendar {
/// In case we plan to cache per-year data, this stores
/// useful computational information for the current year
/// as a field on ArithmeticDate
type YearInfo: Copy + Debug;
// TODO(#3933): potentially make these methods take &self instead, and absorb certain y/m parameters
// based on usage patterns (e.g month_days is only ever called with self.year)
fn month_days(year: i32, month: u8, year_info: Self::YearInfo) -> u8;
fn months_for_every_year(year: i32, year_info: Self::YearInfo) -> u8;
fn is_leap_year(year: i32, year_info: Self::YearInfo) -> bool;
fn last_month_day_in_year(year: i32, year_info: Self::YearInfo) -> (u8, u8);
/// Calculate the days in a given year
/// Can be overridden with simpler implementations for solar calendars
/// (typically, 366 in leap, 365 otherwise) Leave this as the default
/// for lunar calendars
///
/// The name has `provided` in it to avoid clashes with Calendar
fn days_in_provided_year(year: i32, year_info: Self::YearInfo) -> u16 {
let months_in_year = Self::months_for_every_year(year, year_info);
let mut days: u16 = 0;
for month in 1..=months_in_year {
days += Self::month_days(year, month, year_info) as u16;
}
days
}
}
pub(crate) trait PrecomputedDataSource<YearInfo> {
/// Given a calendar year, load (or compute) the YearInfo for it
///
/// In the future we may pass in an optional previous YearInfo alongside the year
/// it matches to allow code to take shortcuts.
fn load_or_compute_info(&self, year: i32) -> YearInfo;
}
impl PrecomputedDataSource<()> for () {
fn load_or_compute_info(&self, _year: i32) {}
}
impl<C: CalendarArithmetic> ArithmeticDate<C> {
/// Create a new `ArithmeticDate` without checking that `month` and `day` are in bounds.
#[inline]
pub const fn new_unchecked(year: i32, month: u8, day: u8) -> Self
where
C: CalendarArithmetic<YearInfo = ()>,
{
Self::new_unchecked_with_info(year, month, day, ())
}
/// Create a new `ArithmeticDate` without checking that `month` and `day` are in bounds.
#[inline]
pub const fn new_unchecked_with_info(
year: i32,
month: u8,
day: u8,
year_info: C::YearInfo,
) -> Self {
ArithmeticDate {
year,
month,
day,
year_info,
marker: PhantomData,
}
}
#[inline]
pub fn min_date() -> Self
where
C: CalendarArithmetic<YearInfo = ()>,
{
ArithmeticDate {
year: i32::MIN,
month: 1,
day: 1,
year_info: (),
marker: PhantomData,
}
}
#[inline]
pub fn max_date() -> Self
where
C: CalendarArithmetic<YearInfo = ()>,
{
let year = i32::MAX;
let (month, day) = C::last_month_day_in_year(year, ());
ArithmeticDate {
year: i32::MAX,
month,
day,
year_info: (),
marker: PhantomData,
}
}
#[inline]
fn offset_days(&mut self, mut day_offset: i32, data: &impl PrecomputedDataSource<C::YearInfo>) {
while day_offset != 0 {
let month_days = C::month_days(self.year, self.month, self.year_info);
if self.day as i32 + day_offset > month_days as i32 {
self.offset_months(1, data);
day_offset -= month_days as i32;
} else if self.day as i32 + day_offset < 1 {
self.offset_months(-1, data);
day_offset += C::month_days(self.year, self.month, self.year_info) as i32;
} else {
self.day = (self.day as i32 + day_offset) as u8;
day_offset = 0;
}
}
}
#[inline]
fn offset_months(
&mut self,
mut month_offset: i32,
data: &impl PrecomputedDataSource<C::YearInfo>,
) {
while month_offset != 0 {
let year_months = C::months_for_every_year(self.year, self.year_info);
if self.month as i32 + month_offset > year_months as i32 {
self.year += 1;
self.year_info = data.load_or_compute_info(self.year);
month_offset -= year_months as i32;
} else if self.month as i32 + month_offset < 1 {
self.year -= 1;
self.year_info = data.load_or_compute_info(self.year);
month_offset += C::months_for_every_year(self.year, self.year_info) as i32;
} else {
self.month = (self.month as i32 + month_offset) as u8;
month_offset = 0
}
}
}
#[inline]
pub fn offset_date(
&mut self,
offset: DateDuration<C>,
data: &impl PrecomputedDataSource<C::YearInfo>,
) {
if offset.years != 0 {
// For offset_date to work with lunar calendars, need to handle an edge case where the original month is not valid in the future year.
self.year += offset.years;
self.year_info = data.load_or_compute_info(self.year);
}
self.offset_months(offset.months, data);
let day_offset = offset.days + offset.weeks * 7 + self.day as i32 - 1;
self.day = 1;
self.offset_days(day_offset, data);
}
#[inline]
pub fn until(
&self,
date2: ArithmeticDate<C>,
_largest_unit: DateDurationUnit,
_smaller_unit: DateDurationUnit,
) -> DateDuration<C> {
// This simple implementation does not need C::PrecomputedDataSource right now, but it
// likely will once we've written a proper implementation
DateDuration::new(
self.year - date2.year,
self.month as i32 - date2.month as i32,
0,
self.day as i32 - date2.day as i32,
)
}
#[inline]
pub fn days_in_year(&self) -> u16 {
C::days_in_provided_year(self.year, self.year_info)
}
#[inline]
pub fn months_in_year(&self) -> u8 {
C::months_for_every_year(self.year, self.year_info)
}
#[inline]
pub fn days_in_month(&self) -> u8 {
C::month_days(self.year, self.month, self.year_info)
}
#[inline]
pub fn day_of_year(&self) -> u16 {
let mut day_of_year = 0;
for month in 1..self.month {
day_of_year += C::month_days(self.year, month, self.year_info) as u16;
}
day_of_year + (self.day as u16)
}
#[inline]
pub fn date_from_year_day(year: i32, year_day: u32) -> ArithmeticDate<C>
where
C: CalendarArithmetic<YearInfo = ()>,
{
let mut month = 1;
let mut day = year_day as i32;
while month <= C::months_for_every_year(year, ()) {
let month_days = C::month_days(year, month, ()) as i32;
if day <= month_days {
break;
} else {
day -= month_days;
month += 1;
}
}
debug_assert!(day <= C::month_days(year, month, ()) as i32);
#[allow(clippy::unwrap_used)]
// The day is expected to be within the range of month_days of C
ArithmeticDate {
year,
month,
day: day.try_into().unwrap_or(0),
year_info: (),
marker: PhantomData,
}
}
#[inline]
pub fn day_of_month(&self) -> types::DayOfMonth {
types::DayOfMonth(self.day.into())
}
/// The [`types::FormattableMonth`] for the current month (with month code) for a solar calendar
/// Lunar calendars should not use this method and instead manually implement a month code
/// resolver.
/// Originally "solar_month" but renamed because it can be used for some lunar calendars
///
/// Returns "und" if run with months that are out of bounds for the current
/// calendar.
#[inline]
pub fn month(&self) -> types::FormattableMonth {
let code = match self.month {
a if a > C::months_for_every_year(self.year, self.year_info) => tinystr!(4, "und"),
1 => tinystr!(4, "M01"),
2 => tinystr!(4, "M02"),
3 => tinystr!(4, "M03"),
4 => tinystr!(4, "M04"),
5 => tinystr!(4, "M05"),
6 => tinystr!(4, "M06"),
7 => tinystr!(4, "M07"),
8 => tinystr!(4, "M08"),
9 => tinystr!(4, "M09"),
10 => tinystr!(4, "M10"),
11 => tinystr!(4, "M11"),
12 => tinystr!(4, "M12"),
13 => tinystr!(4, "M13"),
_ => tinystr!(4, "und"),
};
types::FormattableMonth {
ordinal: self.month as u32,
code: types::MonthCode(code),
}
}
/// Construct a new arithmetic date from a year, month code, and day, bounds checking
/// the month and day
/// Originally (new_from_solar_codes) but renamed because it works for some lunar calendars
pub fn new_from_codes<C2: Calendar>(
// Separate type since the debug_name() impl may differ when DateInner types
// are nested (e.g. in GregorianDateInner)
cal: &C2,
year: i32,
month_code: types::MonthCode,
day: u8,
) -> Result<Self, CalendarError>
where
C: CalendarArithmetic<YearInfo = ()>,
{
let month = if let Some((ordinal, false)) = month_code.parsed() {
ordinal
} else {
return Err(CalendarError::UnknownMonthCode(
month_code.0,
cal.debug_name(),
));
};
if month > C::months_for_every_year(year, ()) {
return Err(CalendarError::UnknownMonthCode(
month_code.0,
cal.debug_name(),
));
}
let max_day = C::month_days(year, month, ());
if day > max_day {
return Err(CalendarError::Overflow {
field: "day",
max: max_day as usize,
});
}
Ok(Self::new_unchecked(year, month, day))
}
/// Construct a new arithmetic date from a year, month ordinal, and day, bounds checking
/// the month and day
/// Originally (new_from_solar_ordinals) but renamed because it works for some lunar calendars
pub fn new_from_ordinals(year: i32, month: u8, day: u8) -> Result<Self, CalendarError>
where
C: CalendarArithmetic<YearInfo = ()>,
{
Self::new_from_ordinals_with_info(year, month, day, ())
}
/// Construct a new arithmetic date from a year, month ordinal, and day, bounds checking
/// the month and day
pub fn new_from_ordinals_with_info(
year: i32,
month: u8,
day: u8,
info: C::YearInfo,
) -> Result<Self, CalendarError> {
let max_month = C::months_for_every_year(year, info);
if month > max_month {
return Err(CalendarError::Overflow {
field: "month",
max: max_month as usize,
});
}
let max_day = C::month_days(year, month, info);
if day > max_day {
return Err(CalendarError::Overflow {
field: "day",
max: max_day as usize,
});
}
Ok(Self::new_unchecked_with_info(year, month, day, info))
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::Iso;
#[test]
fn test_ord() {
let dates_in_order = [
ArithmeticDate::<Iso>::new_unchecked(-10, 1, 1),
ArithmeticDate::<Iso>::new_unchecked(-10, 1, 2),
ArithmeticDate::<Iso>::new_unchecked(-10, 2, 1),
ArithmeticDate::<Iso>::new_unchecked(-1, 1, 1),
ArithmeticDate::<Iso>::new_unchecked(-1, 1, 2),
ArithmeticDate::<Iso>::new_unchecked(-1, 2, 1),
ArithmeticDate::<Iso>::new_unchecked(0, 1, 1),
ArithmeticDate::<Iso>::new_unchecked(0, 1, 2),
ArithmeticDate::<Iso>::new_unchecked(0, 2, 1),
ArithmeticDate::<Iso>::new_unchecked(1, 1, 1),
ArithmeticDate::<Iso>::new_unchecked(1, 1, 2),
ArithmeticDate::<Iso>::new_unchecked(1, 2, 1),
ArithmeticDate::<Iso>::new_unchecked(10, 1, 1),
ArithmeticDate::<Iso>::new_unchecked(10, 1, 2),
ArithmeticDate::<Iso>::new_unchecked(10, 2, 1),
];
for (i, i_date) in dates_in_order.iter().enumerate() {
for (j, j_date) in dates_in_order.iter().enumerate() {
let result1 = i_date.cmp(j_date);
let result2 = j_date.cmp(i_date);
assert_eq!(result1.reverse(), result2);
assert_eq!(i.cmp(&j), i_date.cmp(j_date));
}
}
}
}