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// This is a part of Chrono.
// See README.md and LICENSE.txt for details.
//! The time zone which has a fixed offset from UTC.
use core::fmt;
use core::ops::{Add, Sub};
use oldtime::Duration as OldDuration;
use super::{LocalResult, Offset, TimeZone};
use div::div_mod_floor;
use naive::{NaiveDate, NaiveDateTime, NaiveTime};
use DateTime;
use Timelike;
/// The time zone with fixed offset, from UTC-23:59:59 to UTC+23:59:59.
///
/// Using the [`TimeZone`](./trait.TimeZone.html) methods
/// on a `FixedOffset` struct is the preferred way to construct
/// `DateTime<FixedOffset>` instances. See the [`east`](#method.east) and
/// [`west`](#method.west) methods for examples.
#[derive(PartialEq, Eq, Hash, Copy, Clone)]
pub struct FixedOffset {
local_minus_utc: i32,
}
impl FixedOffset {
/// Makes a new `FixedOffset` for the Eastern Hemisphere with given timezone difference.
/// The negative `secs` means the Western Hemisphere.
///
/// Panics on the out-of-bound `secs`.
///
/// # Example
///
/// ~~~~
/// use chrono::{FixedOffset, TimeZone};
/// let hour = 3600;
/// let datetime = FixedOffset::east(5 * hour).ymd(2016, 11, 08)
/// .and_hms(0, 0, 0);
/// assert_eq!(&datetime.to_rfc3339(), "2016-11-08T00:00:00+05:00")
/// ~~~~
pub fn east(secs: i32) -> FixedOffset {
FixedOffset::east_opt(secs).expect("FixedOffset::east out of bounds")
}
/// Makes a new `FixedOffset` for the Eastern Hemisphere with given timezone difference.
/// The negative `secs` means the Western Hemisphere.
///
/// Returns `None` on the out-of-bound `secs`.
pub fn east_opt(secs: i32) -> Option<FixedOffset> {
if -86_400 < secs && secs < 86_400 {
Some(FixedOffset { local_minus_utc: secs })
} else {
None
}
}
/// Makes a new `FixedOffset` for the Western Hemisphere with given timezone difference.
/// The negative `secs` means the Eastern Hemisphere.
///
/// Panics on the out-of-bound `secs`.
///
/// # Example
///
/// ~~~~
/// use chrono::{FixedOffset, TimeZone};
/// let hour = 3600;
/// let datetime = FixedOffset::west(5 * hour).ymd(2016, 11, 08)
/// .and_hms(0, 0, 0);
/// assert_eq!(&datetime.to_rfc3339(), "2016-11-08T00:00:00-05:00")
/// ~~~~
pub fn west(secs: i32) -> FixedOffset {
FixedOffset::west_opt(secs).expect("FixedOffset::west out of bounds")
}
/// Makes a new `FixedOffset` for the Western Hemisphere with given timezone difference.
/// The negative `secs` means the Eastern Hemisphere.
///
/// Returns `None` on the out-of-bound `secs`.
pub fn west_opt(secs: i32) -> Option<FixedOffset> {
if -86_400 < secs && secs < 86_400 {
Some(FixedOffset { local_minus_utc: -secs })
} else {
None
}
}
/// Returns the number of seconds to add to convert from UTC to the local time.
#[inline]
pub fn local_minus_utc(&self) -> i32 {
self.local_minus_utc
}
/// Returns the number of seconds to add to convert from the local time to UTC.
#[inline]
pub fn utc_minus_local(&self) -> i32 {
-self.local_minus_utc
}
}
impl TimeZone for FixedOffset {
type Offset = FixedOffset;
fn from_offset(offset: &FixedOffset) -> FixedOffset {
*offset
}
fn offset_from_local_date(&self, _local: &NaiveDate) -> LocalResult<FixedOffset> {
LocalResult::Single(*self)
}
fn offset_from_local_datetime(&self, _local: &NaiveDateTime) -> LocalResult<FixedOffset> {
LocalResult::Single(*self)
}
fn offset_from_utc_date(&self, _utc: &NaiveDate) -> FixedOffset {
*self
}
fn offset_from_utc_datetime(&self, _utc: &NaiveDateTime) -> FixedOffset {
*self
}
}
impl Offset for FixedOffset {
fn fix(&self) -> FixedOffset {
*self
}
}
impl fmt::Debug for FixedOffset {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let offset = self.local_minus_utc;
let (sign, offset) = if offset < 0 { ('-', -offset) } else { ('+', offset) };
let (mins, sec) = div_mod_floor(offset, 60);
let (hour, min) = div_mod_floor(mins, 60);
if sec == 0 {
write!(f, "{}{:02}:{:02}", sign, hour, min)
} else {
write!(f, "{}{:02}:{:02}:{:02}", sign, hour, min, sec)
}
}
}
impl fmt::Display for FixedOffset {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(self, f)
}
}
// addition or subtraction of FixedOffset to/from Timelike values is the same as
// adding or subtracting the offset's local_minus_utc value
// but keep keeps the leap second information.
// this should be implemented more efficiently, but for the time being, this is generic right now.
fn add_with_leapsecond<T>(lhs: &T, rhs: i32) -> T
where
T: Timelike + Add<OldDuration, Output = T>,
{
// extract and temporarily remove the fractional part and later recover it
let nanos = lhs.nanosecond();
let lhs = lhs.with_nanosecond(0).unwrap();
(lhs + OldDuration::seconds(i64::from(rhs))).with_nanosecond(nanos).unwrap()
}
impl Add<FixedOffset> for NaiveTime {
type Output = NaiveTime;
#[inline]
fn add(self, rhs: FixedOffset) -> NaiveTime {
add_with_leapsecond(&self, rhs.local_minus_utc)
}
}
impl Sub<FixedOffset> for NaiveTime {
type Output = NaiveTime;
#[inline]
fn sub(self, rhs: FixedOffset) -> NaiveTime {
add_with_leapsecond(&self, -rhs.local_minus_utc)
}
}
impl Add<FixedOffset> for NaiveDateTime {
type Output = NaiveDateTime;
#[inline]
fn add(self, rhs: FixedOffset) -> NaiveDateTime {
add_with_leapsecond(&self, rhs.local_minus_utc)
}
}
impl Sub<FixedOffset> for NaiveDateTime {
type Output = NaiveDateTime;
#[inline]
fn sub(self, rhs: FixedOffset) -> NaiveDateTime {
add_with_leapsecond(&self, -rhs.local_minus_utc)
}
}
impl<Tz: TimeZone> Add<FixedOffset> for DateTime<Tz> {
type Output = DateTime<Tz>;
#[inline]
fn add(self, rhs: FixedOffset) -> DateTime<Tz> {
add_with_leapsecond(&self, rhs.local_minus_utc)
}
}
impl<Tz: TimeZone> Sub<FixedOffset> for DateTime<Tz> {
type Output = DateTime<Tz>;
#[inline]
fn sub(self, rhs: FixedOffset) -> DateTime<Tz> {
add_with_leapsecond(&self, -rhs.local_minus_utc)
}
}
#[cfg(test)]
mod tests {
use super::FixedOffset;
use offset::TimeZone;
#[test]
fn test_date_extreme_offset() {
// starting from 0.3 we don't have an offset exceeding one day.
// this makes everything easier!
assert_eq!(
format!("{:?}", FixedOffset::east(86399).ymd(2012, 2, 29)),
"2012-02-29+23:59:59".to_string()
);
assert_eq!(
format!("{:?}", FixedOffset::east(86399).ymd(2012, 2, 29).and_hms(5, 6, 7)),
"2012-02-29T05:06:07+23:59:59".to_string()
);
assert_eq!(
format!("{:?}", FixedOffset::west(86399).ymd(2012, 3, 4)),
"2012-03-04-23:59:59".to_string()
);
assert_eq!(
format!("{:?}", FixedOffset::west(86399).ymd(2012, 3, 4).and_hms(5, 6, 7)),
"2012-03-04T05:06:07-23:59:59".to_string()
);
}
}