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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::any_calendar::AnyCalendarKind;
use crate::{types, CalendarError, Date, DateDuration, DateDurationUnit, Iso};
use core::fmt;
/// A calendar implementation
///
/// Only implementors of [`Calendar`] should care about these methods, in general users of
/// these calendars should use the methods on [`Date`] instead.
///
/// Individual [`Calendar`] implementations may have inherent utility methods
/// allowing for direct construction, etc.
///
/// For ICU4X 1.0, implementing this trait or calling methods directly is considered
/// unstable and prone to change, especially for `offset_date()` and `until()`.
pub trait Calendar {
/// The internal type used to represent dates
type DateInner: PartialEq + Eq + Clone + fmt::Debug;
/// 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>;
/// Construct the date from an ISO date
fn date_from_iso(&self, iso: Date<Iso>) -> Self::DateInner;
/// Obtain an ISO date from this date
fn date_to_iso(&self, date: &Self::DateInner) -> Date<Iso>;
// fn validate_date(&self, e: Era, y: Year, m: MonthCode, d: Day) -> bool;
// // similar validators for YearMonth, etc
// fn is_leap<A: AsCalendar<Calendar = Self>>(&self, date: &Date<A>) -> bool;
/// Count the number of months in a given year, specified by providing a date
/// from that year
fn months_in_year(&self, date: &Self::DateInner) -> u8;
/// Count the number of days in a given year, specified by providing a date
/// from that year
fn days_in_year(&self, date: &Self::DateInner) -> u16;
/// Count the number of days in a given month, specified by providing a date
/// from that year/month
fn days_in_month(&self, date: &Self::DateInner) -> u8;
/// Calculate the day of the week and return it
fn day_of_week(&self, date: &Self::DateInner) -> types::IsoWeekday {
self.date_to_iso(date).day_of_week()
}
// fn week_of_year(&self, date: &Self::DateInner) -> u8;
#[doc(hidden)] // unstable
/// Add `offset` to `date`
fn offset_date(&self, date: &mut Self::DateInner, offset: DateDuration<Self>);
#[doc(hidden)] // unstable
/// Calculate `date2 - date` as a duration
///
/// `calendar2` is the calendar object associated with `date2`. In case the specific calendar objects
/// differ on data, the data for the first calendar is used, and `date2` may be converted if necessary.
fn until(
&self,
date1: &Self::DateInner,
date2: &Self::DateInner,
calendar2: &Self,
largest_unit: DateDurationUnit,
smallest_unit: DateDurationUnit,
) -> DateDuration<Self>;
/// Obtain a name for the calendar for debug printing
fn debug_name(&self) -> &'static str;
// fn since(&self, from: &Date<Self>, to: &Date<Self>) -> Duration<Self>, Error;
/// The calendar-specific year represented by `date`
fn year(&self, date: &Self::DateInner) -> types::FormattableYear;
/// Calculate if a date is in a leap year
fn is_in_leap_year(&self, date: &Self::DateInner) -> bool;
/// The calendar-specific month represented by `date`
fn month(&self, date: &Self::DateInner) -> types::FormattableMonth;
/// The calendar-specific day-of-month represented by `date`
fn day_of_month(&self, date: &Self::DateInner) -> types::DayOfMonth;
/// Information of the day of the year
fn day_of_year_info(&self, date: &Self::DateInner) -> types::DayOfYearInfo;
/// The [`AnyCalendarKind`] corresponding to this calendar,
/// if one exists. Implementors outside of `icu::calendar` should return `None`
fn any_calendar_kind(&self) -> Option<AnyCalendarKind> {
None
}
}