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// This is a part of Chrono.
// See README.md and LICENSE.txt for details.
//! The local (system) time zone.
#[cfg(windows)]
use std::cmp::Ordering;
#[cfg(any(feature = "rkyv", feature = "rkyv-16", feature = "rkyv-32", feature = "rkyv-64"))]
use rkyv::{Archive, Deserialize, Serialize};
use super::fixed::FixedOffset;
use super::{MappedLocalTime, TimeZone};
#[allow(deprecated)]
use crate::Date;
use crate::naive::{NaiveDate, NaiveDateTime, NaiveTime};
use crate::{DateTime, Utc};
#[cfg(unix)]
#[path = "unix.rs"]
mod inner;
#[cfg(windows)]
#[path = "windows.rs"]
mod inner;
#[cfg(all(windows, feature = "clock"))]
#[allow(unreachable_pub)]
mod win_bindings;
#[cfg(all(
not(unix),
not(windows),
not(all(
target_arch = "wasm32",
feature = "wasmbind",
not(any(target_os = "emscripten", target_os = "wasi"))
))
))]
mod inner {
use crate::{FixedOffset, MappedLocalTime, NaiveDateTime};
pub(super) fn offset_from_utc_datetime(
_utc_time: &NaiveDateTime,
) -> MappedLocalTime<FixedOffset> {
MappedLocalTime::Single(FixedOffset::east_opt(0).unwrap())
}
pub(super) fn offset_from_local_datetime(
_local_time: &NaiveDateTime,
) -> MappedLocalTime<FixedOffset> {
MappedLocalTime::Single(FixedOffset::east_opt(0).unwrap())
}
}
#[cfg(all(
target_arch = "wasm32",
feature = "wasmbind",
not(any(target_os = "emscripten", target_os = "wasi"))
))]
mod inner {
use crate::{Datelike, FixedOffset, MappedLocalTime, NaiveDateTime, Timelike};
pub(super) fn offset_from_utc_datetime(utc: &NaiveDateTime) -> MappedLocalTime<FixedOffset> {
let offset = js_sys::Date::from(utc.and_utc()).get_timezone_offset();
MappedLocalTime::Single(FixedOffset::west_opt((offset as i32) * 60).unwrap())
}
pub(super) fn offset_from_local_datetime(
local: &NaiveDateTime,
) -> MappedLocalTime<FixedOffset> {
let mut year = local.year();
if year < 100 {
// The API in `js_sys` does not let us create a `Date` with negative years.
// And values for years from `0` to `99` map to the years `1900` to `1999`.
// Shift the value by a multiple of 400 years until it is `>= 100`.
let shift_cycles = (year - 100).div_euclid(400);
year -= shift_cycles * 400;
}
let js_date = js_sys::Date::new_with_year_month_day_hr_min_sec(
year as u32,
local.month0() as i32,
local.day() as i32,
local.hour() as i32,
local.minute() as i32,
local.second() as i32,
// ignore milliseconds, our representation of leap seconds may be problematic
);
let offset = js_date.get_timezone_offset();
// We always get a result, even if this time does not exist or is ambiguous.
MappedLocalTime::Single(FixedOffset::west_opt((offset as i32) * 60).unwrap())
}
}
#[cfg(unix)]
mod tz_info;
/// The local timescale.
///
/// Using the [`TimeZone`](./trait.TimeZone.html) methods
/// on the Local struct is the preferred way to construct `DateTime<Local>`
/// instances.
///
/// # Example
///
/// ```
/// use chrono::{DateTime, Local, TimeZone};
///
/// let dt1: DateTime<Local> = Local::now();
/// let dt2: DateTime<Local> = Local.timestamp_opt(0, 0).unwrap();
/// assert!(dt1 >= dt2);
/// ```
#[derive(Copy, Clone, Debug)]
#[cfg_attr(
any(feature = "rkyv", feature = "rkyv-16", feature = "rkyv-32", feature = "rkyv-64"),
derive(Archive, Deserialize, Serialize),
archive(compare(PartialEq)),
archive_attr(derive(Clone, Copy, Debug))
)]
#[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
pub struct Local;
impl Local {
/// Returns a `Date` which corresponds to the current date.
#[deprecated(since = "0.4.23", note = "use `Local::now()` instead")]
#[allow(deprecated)]
#[must_use]
pub fn today() -> Date<Local> {
Local::now().date()
}
/// Returns a `DateTime<Local>` which corresponds to the current date, time and offset from
/// UTC.
///
/// See also the similar [`Utc::now()`] which returns `DateTime<Utc>`, i.e. without the local
/// offset.
///
/// # Example
///
/// ```
/// # #![allow(unused_variables)]
/// # use chrono::{DateTime, FixedOffset, Local};
/// // Current local time
/// let now = Local::now();
///
/// // Current local date
/// let today = now.date_naive();
///
/// // Current local time, converted to `DateTime<FixedOffset>`
/// let now_fixed_offset = Local::now().fixed_offset();
/// // or
/// let now_fixed_offset: DateTime<FixedOffset> = Local::now().into();
///
/// // Current time in some timezone (let's use +05:00)
/// // Note that it is usually more efficient to use `Utc::now` for this use case.
/// let offset = FixedOffset::east_opt(5 * 60 * 60).unwrap();
/// let now_with_offset = Local::now().with_timezone(&offset);
/// ```
pub fn now() -> DateTime<Local> {
Utc::now().with_timezone(&Local)
}
}
impl TimeZone for Local {
type Offset = FixedOffset;
fn from_offset(_offset: &FixedOffset) -> Local {
Local
}
#[allow(deprecated)]
fn offset_from_local_date(&self, local: &NaiveDate) -> MappedLocalTime<FixedOffset> {
// Get the offset at local midnight.
self.offset_from_local_datetime(&local.and_time(NaiveTime::MIN))
}
fn offset_from_local_datetime(&self, local: &NaiveDateTime) -> MappedLocalTime<FixedOffset> {
inner::offset_from_local_datetime(local)
}
#[allow(deprecated)]
fn offset_from_utc_date(&self, utc: &NaiveDate) -> FixedOffset {
// Get the offset at midnight.
self.offset_from_utc_datetime(&utc.and_time(NaiveTime::MIN))
}
fn offset_from_utc_datetime(&self, utc: &NaiveDateTime) -> FixedOffset {
inner::offset_from_utc_datetime(utc).unwrap()
}
}
#[cfg(windows)]
#[derive(Copy, Clone, Eq, PartialEq)]
struct Transition {
transition_utc: NaiveDateTime,
offset_before: FixedOffset,
offset_after: FixedOffset,
}
#[cfg(windows)]
impl Transition {
fn new(
transition_local: NaiveDateTime,
offset_before: FixedOffset,
offset_after: FixedOffset,
) -> Transition {
// It is no problem if the transition time in UTC falls a couple of hours inside the buffer
// space around the `NaiveDateTime` range (although it is very theoretical to have a
// transition at midnight around `NaiveDate::(MIN|MAX)`.
let transition_utc = transition_local.overflowing_sub_offset(offset_before);
Transition { transition_utc, offset_before, offset_after }
}
}
#[cfg(windows)]
impl PartialOrd for Transition {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.transition_utc.cmp(&other.transition_utc))
}
}
#[cfg(windows)]
impl Ord for Transition {
fn cmp(&self, other: &Self) -> Ordering {
self.transition_utc.cmp(&other.transition_utc)
}
}
// Calculate the time in UTC given a local time and transitions.
// `transitions` must be sorted.
#[cfg(windows)]
fn lookup_with_dst_transitions(
transitions: &[Transition],
dt: NaiveDateTime,
) -> MappedLocalTime<FixedOffset> {
for t in transitions.iter() {
// A transition can result in the wall clock time going forward (creating a gap) or going
// backward (creating a fold). We are interested in the earliest and latest wall time of the
// transition, as this are the times between which `dt` does may not exist or is ambiguous.
//
// It is no problem if the transition times falls a couple of hours inside the buffer
// space around the `NaiveDateTime` range (although it is very theoretical to have a
// transition at midnight around `NaiveDate::(MIN|MAX)`.
let (offset_min, offset_max) =
match t.offset_after.local_minus_utc() > t.offset_before.local_minus_utc() {
true => (t.offset_before, t.offset_after),
false => (t.offset_after, t.offset_before),
};
let wall_earliest = t.transition_utc.overflowing_add_offset(offset_min);
let wall_latest = t.transition_utc.overflowing_add_offset(offset_max);
if dt < wall_earliest {
return MappedLocalTime::Single(t.offset_before);
} else if dt <= wall_latest {
return match t.offset_after.local_minus_utc().cmp(&t.offset_before.local_minus_utc()) {
Ordering::Equal => MappedLocalTime::Single(t.offset_before),
Ordering::Less => MappedLocalTime::Ambiguous(t.offset_before, t.offset_after),
Ordering::Greater => {
if dt == wall_earliest {
MappedLocalTime::Single(t.offset_before)
} else if dt == wall_latest {
MappedLocalTime::Single(t.offset_after)
} else {
MappedLocalTime::None
}
}
};
}
}
MappedLocalTime::Single(transitions.last().unwrap().offset_after)
}
#[cfg(test)]
mod tests {
use super::Local;
use crate::offset::TimeZone;
#[cfg(windows)]
use crate::offset::local::{Transition, lookup_with_dst_transitions};
use crate::{Datelike, Days, Utc};
#[cfg(windows)]
use crate::{FixedOffset, MappedLocalTime, NaiveDate, NaiveDateTime};
#[test]
fn verify_correct_offsets() {
let now = Local::now();
let from_local = Local.from_local_datetime(&now.naive_local()).unwrap();
let from_utc = Local.from_utc_datetime(&now.naive_utc());
assert_eq!(now.offset().local_minus_utc(), from_local.offset().local_minus_utc());
assert_eq!(now.offset().local_minus_utc(), from_utc.offset().local_minus_utc());
assert_eq!(now, from_local);
assert_eq!(now, from_utc);
}
#[test]
fn verify_correct_offsets_distant_past() {
let distant_past = Local::now() - Days::new(365 * 500);
let from_local = Local.from_local_datetime(&distant_past.naive_local()).unwrap();
let from_utc = Local.from_utc_datetime(&distant_past.naive_utc());
assert_eq!(distant_past.offset().local_minus_utc(), from_local.offset().local_minus_utc());
assert_eq!(distant_past.offset().local_minus_utc(), from_utc.offset().local_minus_utc());
assert_eq!(distant_past, from_local);
assert_eq!(distant_past, from_utc);
}
#[test]
fn verify_correct_offsets_distant_future() {
let distant_future = Local::now() + Days::new(365 * 35000);
let from_local = Local.from_local_datetime(&distant_future.naive_local()).unwrap();
let from_utc = Local.from_utc_datetime(&distant_future.naive_utc());
assert_eq!(
distant_future.offset().local_minus_utc(),
from_local.offset().local_minus_utc()
);
assert_eq!(distant_future.offset().local_minus_utc(), from_utc.offset().local_minus_utc());
assert_eq!(distant_future, from_local);
assert_eq!(distant_future, from_utc);
}
#[test]
fn test_local_date_sanity_check() {
// issue #27
assert_eq!(Local.with_ymd_and_hms(2999, 12, 28, 0, 0, 0).unwrap().day(), 28);
}
#[test]
fn test_leap_second() {
// issue #123
let today = Utc::now().date_naive();
if let Some(dt) = today.and_hms_milli_opt(15, 2, 59, 1000) {
let timestr = dt.time().to_string();
// the OS API may or may not support the leap second,
// but there are only two sensible options.
assert!(
timestr == "15:02:60" || timestr == "15:03:00",
"unexpected timestr {:?}",
timestr
);
}
if let Some(dt) = today.and_hms_milli_opt(15, 2, 3, 1234) {
let timestr = dt.time().to_string();
assert!(
timestr == "15:02:03.234" || timestr == "15:02:04.234",
"unexpected timestr {:?}",
timestr
);
}
}
#[test]
#[cfg(windows)]
fn test_lookup_with_dst_transitions() {
let ymdhms = |y, m, d, h, n, s| {
NaiveDate::from_ymd_opt(y, m, d).unwrap().and_hms_opt(h, n, s).unwrap()
};
#[track_caller]
#[allow(clippy::too_many_arguments)]
fn compare_lookup(
transitions: &[Transition],
y: i32,
m: u32,
d: u32,
h: u32,
n: u32,
s: u32,
result: MappedLocalTime<FixedOffset>,
) {
let dt = NaiveDate::from_ymd_opt(y, m, d).unwrap().and_hms_opt(h, n, s).unwrap();
assert_eq!(lookup_with_dst_transitions(transitions, dt), result);
}
// dst transition before std transition
// dst offset > std offset
let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
let dst = FixedOffset::east_opt(4 * 60 * 60).unwrap();
let transitions = [
Transition::new(ymdhms(2023, 3, 26, 2, 0, 0), std, dst),
Transition::new(ymdhms(2023, 10, 29, 3, 0, 0), dst, std),
];
compare_lookup(&transitions, 2023, 3, 26, 1, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 3, 26, 2, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 3, 26, 2, 30, 0, MappedLocalTime::None);
compare_lookup(&transitions, 2023, 3, 26, 3, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 3, 26, 4, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 10, 29, 1, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 10, 29, 2, 0, 0, MappedLocalTime::Ambiguous(dst, std));
compare_lookup(&transitions, 2023, 10, 29, 2, 30, 0, MappedLocalTime::Ambiguous(dst, std));
compare_lookup(&transitions, 2023, 10, 29, 3, 0, 0, MappedLocalTime::Ambiguous(dst, std));
compare_lookup(&transitions, 2023, 10, 29, 4, 0, 0, MappedLocalTime::Single(std));
// std transition before dst transition
// dst offset > std offset
let std = FixedOffset::east_opt(-5 * 60 * 60).unwrap();
let dst = FixedOffset::east_opt(-4 * 60 * 60).unwrap();
let transitions = [
Transition::new(ymdhms(2023, 3, 24, 3, 0, 0), dst, std),
Transition::new(ymdhms(2023, 10, 27, 2, 0, 0), std, dst),
];
compare_lookup(&transitions, 2023, 3, 24, 1, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 3, 24, 2, 0, 0, MappedLocalTime::Ambiguous(dst, std));
compare_lookup(&transitions, 2023, 3, 24, 2, 30, 0, MappedLocalTime::Ambiguous(dst, std));
compare_lookup(&transitions, 2023, 3, 24, 3, 0, 0, MappedLocalTime::Ambiguous(dst, std));
compare_lookup(&transitions, 2023, 3, 24, 4, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 10, 27, 1, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 10, 27, 2, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 10, 27, 2, 30, 0, MappedLocalTime::None);
compare_lookup(&transitions, 2023, 10, 27, 3, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 10, 27, 4, 0, 0, MappedLocalTime::Single(dst));
// dst transition before std transition
// dst offset < std offset
let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
let dst = FixedOffset::east_opt((2 * 60 + 30) * 60).unwrap();
let transitions = [
Transition::new(ymdhms(2023, 3, 26, 2, 30, 0), std, dst),
Transition::new(ymdhms(2023, 10, 29, 2, 0, 0), dst, std),
];
compare_lookup(&transitions, 2023, 3, 26, 1, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 3, 26, 2, 0, 0, MappedLocalTime::Ambiguous(std, dst));
compare_lookup(&transitions, 2023, 3, 26, 2, 15, 0, MappedLocalTime::Ambiguous(std, dst));
compare_lookup(&transitions, 2023, 3, 26, 2, 30, 0, MappedLocalTime::Ambiguous(std, dst));
compare_lookup(&transitions, 2023, 3, 26, 3, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 10, 29, 1, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 10, 29, 2, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 10, 29, 2, 15, 0, MappedLocalTime::None);
compare_lookup(&transitions, 2023, 10, 29, 2, 30, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 10, 29, 3, 0, 0, MappedLocalTime::Single(std));
// std transition before dst transition
// dst offset < std offset
let std = FixedOffset::east_opt(-(4 * 60 + 30) * 60).unwrap();
let dst = FixedOffset::east_opt(-5 * 60 * 60).unwrap();
let transitions = [
Transition::new(ymdhms(2023, 3, 24, 2, 0, 0), dst, std),
Transition::new(ymdhms(2023, 10, 27, 2, 30, 0), std, dst),
];
compare_lookup(&transitions, 2023, 3, 24, 1, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 3, 24, 2, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 3, 24, 2, 15, 0, MappedLocalTime::None);
compare_lookup(&transitions, 2023, 3, 24, 2, 30, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 3, 24, 3, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 10, 27, 1, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 10, 27, 2, 0, 0, MappedLocalTime::Ambiguous(std, dst));
compare_lookup(&transitions, 2023, 10, 27, 2, 15, 0, MappedLocalTime::Ambiguous(std, dst));
compare_lookup(&transitions, 2023, 10, 27, 2, 30, 0, MappedLocalTime::Ambiguous(std, dst));
compare_lookup(&transitions, 2023, 10, 27, 3, 0, 0, MappedLocalTime::Single(dst));
// offset stays the same
let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
let transitions = [
Transition::new(ymdhms(2023, 3, 26, 2, 0, 0), std, std),
Transition::new(ymdhms(2023, 10, 29, 3, 0, 0), std, std),
];
compare_lookup(&transitions, 2023, 3, 26, 2, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 10, 29, 3, 0, 0, MappedLocalTime::Single(std));
// single transition
let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
let dst = FixedOffset::east_opt(4 * 60 * 60).unwrap();
let transitions = [Transition::new(ymdhms(2023, 3, 26, 2, 0, 0), std, dst)];
compare_lookup(&transitions, 2023, 3, 26, 1, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 3, 26, 2, 0, 0, MappedLocalTime::Single(std));
compare_lookup(&transitions, 2023, 3, 26, 2, 30, 0, MappedLocalTime::None);
compare_lookup(&transitions, 2023, 3, 26, 3, 0, 0, MappedLocalTime::Single(dst));
compare_lookup(&transitions, 2023, 3, 26, 4, 0, 0, MappedLocalTime::Single(dst));
}
#[test]
#[cfg(windows)]
fn test_lookup_with_dst_transitions_limits() {
// Transition beyond UTC year end doesn't panic in year of `NaiveDate::MAX`
let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
let dst = FixedOffset::east_opt(4 * 60 * 60).unwrap();
let transitions = [
Transition::new(NaiveDateTime::MAX.with_month(7).unwrap(), std, dst),
Transition::new(NaiveDateTime::MAX, dst, std),
];
assert_eq!(
lookup_with_dst_transitions(&transitions, NaiveDateTime::MAX.with_month(3).unwrap()),
MappedLocalTime::Single(std)
);
assert_eq!(
lookup_with_dst_transitions(&transitions, NaiveDateTime::MAX.with_month(8).unwrap()),
MappedLocalTime::Single(dst)
);
// Doesn't panic with `NaiveDateTime::MAX` as argument (which would be out of range when
// converted to UTC).
assert_eq!(
lookup_with_dst_transitions(&transitions, NaiveDateTime::MAX),
MappedLocalTime::Ambiguous(dst, std)
);
// Transition before UTC year end doesn't panic in year of `NaiveDate::MIN`
let std = FixedOffset::west_opt(3 * 60 * 60).unwrap();
let dst = FixedOffset::west_opt(4 * 60 * 60).unwrap();
let transitions = [
Transition::new(NaiveDateTime::MIN, std, dst),
Transition::new(NaiveDateTime::MIN.with_month(6).unwrap(), dst, std),
];
assert_eq!(
lookup_with_dst_transitions(&transitions, NaiveDateTime::MIN.with_month(3).unwrap()),
MappedLocalTime::Single(dst)
);
assert_eq!(
lookup_with_dst_transitions(&transitions, NaiveDateTime::MIN.with_month(8).unwrap()),
MappedLocalTime::Single(std)
);
// Doesn't panic with `NaiveDateTime::MIN` as argument (which would be out of range when
// converted to UTC).
assert_eq!(
lookup_with_dst_transitions(&transitions, NaiveDateTime::MIN),
MappedLocalTime::Ambiguous(std, dst)
);
}
#[test]
#[cfg(feature = "rkyv-validation")]
fn test_rkyv_validation() {
let local = Local;
// Local is a ZST and serializes to 0 bytes
let bytes = rkyv::to_bytes::<_, 0>(&local).unwrap();
assert_eq!(bytes.len(), 0);
// but is deserialized to an archived variant without a
// wrapping object
assert_eq!(rkyv::from_bytes::<Local>(&bytes).unwrap(), super::ArchivedLocal);
}
}