Crate icu_calendar

Expand description

The icu_calendar crate contains the core types used by ICU4X for dealing with dates, times, and custom calendars.

The types module has a lot of common types for dealing with dates and times.

Calendar is a trait that allows one to define custom calendars, and Date can represent dates for arbitrary calendars.

The iso and gregorian modules contain implementations for the ISO and Gregorian calendars respectively.

Some of the algorithms implemented here are based on Dershowitz, Nachum, and Edward M. Reingold. Calendrical calculations. Cambridge University Press, 2008. with associated Lisp code found at https://github.com/EdReingold/calendar-code2.

Examples

Examples of date manipulation using Date object. Date objects are useful for working with dates, encompassing information about the day, month, year, as well as the calendar type.

use icu_calendar::{Date,
                   DateDuration,
                   DateDurationUnit,
                   types::IsoWeekday};

// Creating ISO date: 1992-09-02.
let mut date_iso = Date::new_iso_date_from_integers(1992, 9, 2).unwrap();
assert_eq!(date_iso.day_of_week(), IsoWeekday::Wednesday);
assert_eq!(date_iso.year().number, 1992);
assert_eq!(date_iso.month().number, 9);
assert_eq!(date_iso.day_of_month().0, 2);

// Answering questions about days in month and year.
assert_eq!(date_iso.days_in_year(), 366);
assert_eq!(date_iso.days_in_month(), 30);

// Advancing date in-place by 1 year, 2 months, 3 weeks, 4 days.
date_iso.add(DateDuration::new(1, 2, 3, 4));
assert_eq!(date_iso.year().number, 1993);
assert_eq!(date_iso.month().number, 11);
assert_eq!(date_iso.day_of_month().0, 27);

// Reverse date advancement.
date_iso.add(DateDuration::new(-1, -2, -3, -4));
assert_eq!(date_iso.year().number, 1992);
assert_eq!(date_iso.month().number, 9);
assert_eq!(date_iso.day_of_month().0, 2);

// Creating ISO date: 2022-01-30.
let newer_date_iso = Date::new_iso_date_from_integers(2022, 1, 30).unwrap();

// Comparing dates: 2022-01-30 and 1992-09-02.
let duration = newer_date_iso.until(&date_iso, DateDurationUnit::Years, DateDurationUnit::Days);
assert_eq!(duration.years, 30);
assert_eq!(duration.months, -8);
assert_eq!(duration.days, 28);

// Create new date with date advancement. Reassign to new variable.
let mutated_date_iso = date_iso.added(DateDuration::new(1, 2, 3, 4));
assert_eq!(mutated_date_iso.year().number, 1993);
assert_eq!(mutated_date_iso.month().number, 11);
assert_eq!(mutated_date_iso.day_of_month().0, 27);

Example of converting an ISO date across Indian and Buddhist calendars.

use icu_calendar::{Date,
                   buddhist::Buddhist,
                   indian::Indian};

// Creating ISO date: 1992-09-02.
let mut date_iso = Date::new_iso_date_from_integers(1992, 9, 2).unwrap();
assert_eq!(date_iso.year().number, 1992);
assert_eq!(date_iso.month().number, 9);
assert_eq!(date_iso.day_of_month().0, 2);

// Conversion into Indian calendar: 1914-08-02.
let date_indian = date_iso.to_calendar(Indian);
assert_eq!(date_indian.year().number, 1914);
assert_eq!(date_indian.month().number, 8);
assert_eq!(date_indian.day_of_month().0, 30);

// Conversion into Buddhist calendar: 2535-09-02.
let date_buddhist = date_iso.to_calendar(Buddhist);
assert_eq!(date_buddhist.year().number, 2535);
assert_eq!(date_buddhist.month().number, 9);
assert_eq!(date_buddhist.day_of_month().0, 2);

Example using DateTime object. Similar to Date objects, DateTime objects contain an accessible Date object containing information about the day, month, year, and calendar type. Additionally, DateTime objects contain an accessible Time object, including granularity of hour, minute, second, and nanosecond.

use icu_calendar::{DateTime,
                   DateDuration,
                   types::IsoWeekday,
                   types::IsoHour,
                   types::IsoMinute,
                   types::IsoSecond,
                   types::NanoSecond,
                   types::Time};

// Creating ISO date: 1992-09-02 8:59
let mut datetime_iso = DateTime::new_iso_datetime_from_integers(1992, 9, 2, 8, 59, 0).unwrap();
assert_eq!(datetime_iso.date.day_of_week(), IsoWeekday::Wednesday);
assert_eq!(datetime_iso.date.year().number, 1992);
assert_eq!(datetime_iso.date.month().number, 9);
assert_eq!(datetime_iso.date.day_of_month().0, 2);
assert_eq!(datetime_iso.time.hour, IsoHour::new_unchecked(8));
assert_eq!(datetime_iso.time.minute, IsoMinute::new_unchecked(59));
assert_eq!(datetime_iso.time.second, IsoSecond::new_unchecked(0));
assert_eq!(datetime_iso.time.nanosecond, NanoSecond::new_unchecked(0));

// Advancing date by 1 year, 2 months, 3 weeks, 4 days.
datetime_iso.date.add(DateDuration::new(1, 2, 3, 4));
// New time of 14:30
datetime_iso.time = Time::try_new(14, 30, 0, 0).unwrap();

assert_eq!(datetime_iso.date.year().number, 1993);
assert_eq!(datetime_iso.date.month().number, 11);
assert_eq!(datetime_iso.date.day_of_month().0, 27);
assert_eq!(datetime_iso.time.hour, IsoHour::new_unchecked(14));
assert_eq!(datetime_iso.time.minute, IsoMinute::new_unchecked(30));
assert_eq!(datetime_iso.time.second, IsoSecond::new_unchecked(0));
assert_eq!(datetime_iso.time.nanosecond, NanoSecond::new_unchecked(0));