koyomi-rs

koyomi-rs is a calendar utility for Japan that depends chrono crate.

About

This can determine Japanese holidays and no configuration file or database maintenance is required.

In addition, you can derive and determine various Japanese-specific definitions related to dates (year, month, and day).

Installation

Add koyomi-rs as a dependency in your Cargo.toml.

cargo add koyomi-rs

[dependencies]
koyomi-rs = "0.1"

Usage

Japanese holidays

Using a struct that implements Datelike from chrono, you can determine whether a specific date corresponds to a Japanese holiday.

To use it, do the following.

use chrono::NaiveDate;
use koyomi_rs::JapaneseHoliday;

let date = NaiveDate::from_ymd_opt(2024, 1, 1).unwrap();
let holiday = JapaneseHoliday::holiday(&date); // Some(JapaneseHoliday::NewYearsDay);

// You can also determine whether it's a specific holiday.
let holiday = JapaneseHoliday::marine_day(&date); // None

Japanese era

Using a struct that implements Datelike from chrono, you can determine Japanese era. Please note that only the eras up to the 明治 are supported for past era names.

To use it, do the following.

use chrono::NaiveDate;
use koyomi_rs::JapaneseEra;

let date = NaiveDate::from_ymd_opt(2024, 1, 1).unwrap();
let era = JapaneseEra::from_datelike(&date); // Some(JapaneseEra::Reiwa(6))

Japanese month

Using a struct that implements Datelike from chrono, you can determine Japanese era.

To use it, do the following.

use chrono::NaiveDate;
use koyomi_rs::JapaneseMonth;

let date = NaiveDate::from_ymd_opt(2024, 1, 1).unwrap();
let month = JapaneseMonth::from_datelike(&date); // JapaneseMonth::Mutsuki;

Japanese weekday

Using a struct that implements Datelike from chrono, you can determine Japanese weekday.

To use it, do the following.

use chrono::NaiveDate;
use koyomi_rs::JapaneseWeekday;

let date = NaiveDate::from_ymd_opt(2024, 1, 1).unwrap();
let zodiac = JapaneseWeekday::from_datelike(&date); // JapaneseWeekday::Getsu;

Japanese zodiac, etc.

Using a struct that implements Datelike from chrono, you can determine Japanese zodiac.

To use it, do the following.

use chrono::NaiveDate;
use koyomi_rs::JapaneseZodiac;

let date = NaiveDate::from_ymd_opt(2024, 1, 1).unwrap();
let zodiac = JapaneseZodiac::from_datelike(&date); // JapaneseZodiac::Tatsu;

Please refer to the documentation for Japanese-specific definitions related to years other than the zodiac signs.

Japanese calendar

You can also generate a calendar that includes all of the above.

To use it as a Japanese calendar, do the following.

use koyomi_rs::Koyomi;

// Koyomi implements Iterator trait.
let mut calendar = Koyomi::year_of(2024);
let date = calendar.next().unwrap();

date.sexagenary_cycle_name(); // 甲辰
date.heavenly_stem_name();    // 甲
date.zodiac_name();           // 辰
date.western_year();          // 2024
date.era_name();              // Some("令和")

date.month_number();          // 1
date.month_name();            // 睦月

date.day();                   // 1
date.weekday_name();          // 月
date.holiday_name();          // Some("元日")

Note

koyomi-rs only handles dates (year, month, and day) and cannot handle hours, minutes, or seconds.

License

MIT