//! Utility functions.
use crate::hint;
/// Versions of functions that are optimized for when the year has already been range-validated.
///
/// The implementations of these functions depend on whether the `large-dates` feature is enabled.
///
/// Note: This module is not exposed by the `time` crate. It is an implementation detail.
pub mod range_validated {
/// Returns if the provided year is a leap year in the proleptic Gregorian calendar, assuming
/// the year has already been range-validated.
///
/// Behavior is unspecified for years outside the valid range.
///
/// Note: This function is not exposed by the `time` crate. It is an implementation detail.
#[inline]
#[track_caller]
pub const fn is_leap_year(year: i32) -> bool {
#[cfg(feature =
"large-dates")]
{
super::is_leap_year(year)
}
#[cfg(not(feature =
"large-dates"))]
{
debug_assert!(year >= -
9999);
debug_assert!(year <=
9999);
year.unsigned_abs().wrapping_mul(
0x20003D7) &
0x6007C0F <=
0x7C00
}
}
/// Get the number of calendar days in a given year, assuming the year has already been
/// range-validated.
///
/// Behavior is unspecified for years outside the valid range.
///
/// Note: This function is not exposed by the `time` crate. It is an implementation detail.
#[inline]
#[track_caller]
pub const fn days_in_year(year: i32) -> u16 {
#[cfg(feature =
"large-dates")]
{
super::days_in_year(year)
}
#[cfg(not(feature =
"large-dates"))]
{
if is_leap_year(year) {
366 }
else {
365 }
}
}
/// Get the number of days in the month of a given year, assuming the year has already been
/// range-validated.
///
/// Note: This function is not exposed by the `time` crate. It is an implementation detail.
#[inline]
#[track_caller]
pub const fn days_in_month(month: u8, year: i32) -> u8 {
#[cfg(feature =
"large-dates")]
{
super::days_in_month(month, year)
}
#[cfg(not(feature =
"large-dates"))]
{
super::days_in_month_leap(month, is_leap_year(year))
}
}
}
/// Returns if the provided year is a leap year in the proleptic Gregorian calendar. Uses
/// [astronomical year numbering](https://en.wikipedia.org/wiki/Astronomical_year_numbering).
///
/// ```rust
/// # use time::util::is_leap_year;
/// assert!(!is_leap_year(1900));
/// assert!(is_leap_year(2000));
/// assert!(is_leap_year(2004));
/// assert!(!is_leap_year(2005));
/// assert!(!is_leap_year(2100));
/// ```
// https://hueffner.de/falk/blog/a-leap-year-check-in-three-instructions.html
#[inline]
pub const fn is_leap_year(year: i32) -> bool {
(year
as i64)
.unsigned_abs()
.wrapping_mul(
0x4000_0000_28F5_C28F)
&
0xC000_000F_8000_000F
<=
0xF_8000_0000
}
/// Get the number of calendar days in a given year.
///
/// The returned value will always be either 365 or 366.
///
/// ```rust
/// # use time::util::days_in_year;
/// assert_eq!(days_in_year(1900), 365);
/// assert_eq!(days_in_year(2000), 366);
/// assert_eq!(days_in_year(2004), 366);
/// assert_eq!(days_in_year(2005), 365);
/// assert_eq!(days_in_year(2100), 365);
/// ```
#[inline]
pub const fn days_in_year(year: i32) -> u16 {
if is_leap_year(year) {
366 }
else {
365 }
}
/// Get the number of weeks in the ISO year.
///
/// The returned value will always be either 52 or 53.
///
/// ```rust
/// # use time::util::weeks_in_year;
/// assert_eq!(weeks_in_year(2019), 52);
/// assert_eq!(weeks_in_year(2020), 53);
/// ```
#[inline]
pub const fn weeks_in_year(year: i32) -> u8 {
match year %
400 {
-
396 | -
391 | -
385 | -
380 | -
374 | -
368 | -
363 | -
357 | -
352 | -
346 | -
340 | -
335
| -
329 | -
324 | -
318 | -
312 | -
307 | -
301 | -
295 | -
289 | -
284 | -
278 | -
272 | -
267
| -
261 | -
256 | -
250 | -
244 | -
239 | -
233 | -
228 | -
222 | -
216 | -
211 | -
205 | -
199
| -
193 | -
188 | -
182 | -
176 | -
171 | -
165 | -
160 | -
154 | -
148 | -
143 | -
137 | -
132
| -
126 | -
120 | -
115 | -
109 | -
104 | -
97 | -
92 | -
86 | -
80 | -
75 | -
69 | -
64 | -
58
| -
52 | -
47 | -
41 | -
36 | -
30 | -
24 | -
19 | -
13 | -
8 | -
2 |
4 |
9 |
15 |
20 |
26 |
32
|
37 |
43 |
48 |
54 |
60 |
65 |
71 |
76 |
82 |
88 |
93 |
99 |
105 |
111 |
116 |
122
|
128 |
133 |
139 |
144 |
150 |
156 |
161 |
167 |
172 |
178 |
184 |
189 |
195 |
201
|
207 |
212 |
218 |
224 |
229 |
235 |
240 |
246 |
252 |
257 |
263 |
268 |
274 |
280
|
285 |
291 |
296 |
303 |
308 |
314 |
320 |
325 |
331 |
336 |
342 |
348 |
353 |
359
|
364 |
370 |
376 |
381 |
387 |
392 |
398 =>
53,
_ =>
52,
}
}
/// Get the number of days in the month of a given year.
///
/// ```rust
/// # use time_core::util::days_in_month;
/// assert_eq!(days_in_month(2, 2020), 29);
/// ```
///
/// Note: This function is not exposed by the `time` crate. It is an implementation detail.
#[inline]
#[track_caller]
pub const fn days_in_month(month: u8, year: i32) -> u8 {
days_in_month_leap(month, is_leap_year(year))
}
/// Get the number of days in the month. The year does not need to be known, but whether the
/// year is a leap year does.
///
/// Note: This function is not exposed by the `time` crate. It is an implementation detail.
#[inline]
#[track_caller]
pub const fn days_in_month_leap(month: u8, is_leap_year: bool) -> u8 {
debug_assert!(month >=
1);
debug_assert!(month <=
12);
if hint::unlikely(month ==
2) {
if is_leap_year {
29 }
else {
28 }
}
else {
30 | month ^ (month >>
3)
}
}
