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// This file is part of ICU4X.
//
// The contents of this file implement algorithms from Calendrical Calculations
// by Reingold & Dershowitz, Cambridge University Press, 4th edition (2018),
// under the Apache-2.0 license. Accordingly, this file is released under
// the Apache License, Version 2.0 which can be found at the calendrical_calculations
use core::fmt;
use core::ops::{Add, AddAssign, Sub, SubAssign};
#[allow(unused_imports)]
use core_maths::*;
/// The *Rata Die*, or *R.D.*, or `fixed_date`: number of days since January 1, 1 CE.
///
///
/// It is a logic error to construct a RataDie
/// except from a date that is in range of one of the official calendars.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
pub struct RataDie(i64);
impl RataDie {
/// Create a RataDie
pub const fn new(fixed_date: i64) -> Self {
let result = Self(fixed_date);
#[cfg(debug_assertions)]
result.check();
result
}
/// Check that it is in range
#[cfg(debug_assertions)]
pub const fn check(&self) {
if self.0 > i64::MAX / 256 {
debug_assert!(
false,
"RataDie is not designed to store values near to the overflow boundary"
);
}
if self.0 < i64::MIN / 256 {
debug_assert!(
false,
"RataDie is not designed to store values near to the overflow boundary"
);
}
}
/// A valid RataDie that is intended to be below all dates representable in calendars
///
/// For testing only
#[doc(hidden)]
pub const fn big_negative() -> Self {
Self::new(i64::MIN / 256 / 256)
}
/// Convert this to an i64 value representing the RataDie
pub const fn to_i64_date(self) -> i64 {
self.0
}
/// Convert this to an f64 value representing the RataDie
pub const fn to_f64_date(self) -> f64 {
self.0 as f64
}
/// Calculate the number of days between two RataDie in a const-friendly way
pub const fn const_diff(self, rhs: Self) -> i64 {
self.0 - rhs.0
}
/// Convert this to a [`Moment`]
pub const fn as_moment(&self) -> Moment {
Moment::new(self.0 as f64)
}
}
impl fmt::Debug for RataDie {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let rd = self.0;
if let Ok((y, m, d)) = crate::iso::iso_from_fixed(*self) {
write!(f, "{rd} R.D. ({y}-{m:02}-{d:02})")
} else {
write!(f, "{rd} R.D. (out of bounds)")
}
}
}
/// Shift a RataDie N days into the future
impl Add<i64> for RataDie {
type Output = Self;
fn add(self, rhs: i64) -> Self::Output {
let result = Self(self.0 + rhs);
#[cfg(debug_assertions)]
result.check();
result
}
}
impl AddAssign<i64> for RataDie {
fn add_assign(&mut self, rhs: i64) {
self.0 += rhs;
#[cfg(debug_assertions)]
self.check();
}
}
/// Shift a RataDie N days into the past
impl Sub<i64> for RataDie {
type Output = Self;
fn sub(self, rhs: i64) -> Self::Output {
let result = Self(self.0 - rhs);
#[cfg(debug_assertions)]
result.check();
result
}
}
impl SubAssign<i64> for RataDie {
fn sub_assign(&mut self, rhs: i64) {
self.0 -= rhs;
#[cfg(debug_assertions)]
self.check();
}
}
/// Calculate the number of days between two RataDie
impl Sub for RataDie {
type Output = i64;
fn sub(self, rhs: Self) -> Self::Output {
self.0 - rhs.0
}
}
/// A moment is a RataDie with a fractional part giving the time of day.
///
/// NOTE: This should not cause overflow errors for most cases, but consider
/// alternative implementations if necessary.
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd)]
pub struct Moment(f64);
/// Add a number of days to a Moment
impl Add<f64> for Moment {
type Output = Self;
fn add(self, rhs: f64) -> Self::Output {
Self(self.0 + rhs)
}
}
impl AddAssign<f64> for Moment {
fn add_assign(&mut self, rhs: f64) {
self.0 += rhs;
}
}
/// Subtract a number of days from a Moment
impl Sub<f64> for Moment {
type Output = Self;
fn sub(self, rhs: f64) -> Self::Output {
Self(self.0 - rhs)
}
}
impl SubAssign<f64> for Moment {
fn sub_assign(&mut self, rhs: f64) {
self.0 -= rhs;
}
}
/// Calculate the number of days between two moments
impl Sub for Moment {
type Output = f64;
fn sub(self, rhs: Self) -> Self::Output {
self.0 - rhs.0
}
}
impl Moment {
/// Create a new moment
pub const fn new(value: f64) -> Moment {
Moment(value)
}
/// Get the inner field of a Moment
pub const fn inner(&self) -> f64 {
self.0
}
/// Get the RataDie of a Moment
pub fn as_rata_die(&self) -> RataDie {
RataDie::new(self.0.floor() as i64)
}
}
#[test]
fn test_moment_to_rata_die_conversion() {
for i in -1000..=1000 {
let moment = Moment::new(i as f64);
let rata_die = moment.as_rata_die();
assert_eq!(rata_die.to_i64_date(), i);
}
}