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Merged
pitdicker merged 2 commits into from
Sep 25, 2023
Merged

(overflowing|checked)_(add|sub)_offset implementations #1069

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225cfaa
Move `Add` and `Sub` impls for `Fixedoffset` to `datetime` modules
pitdicker May 19, 2023
018be06
Use `checked_(add|sub)_offset` in `Add` and `Sub` impls of `DateTime`
pitdicker May 19, 2023
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20 changes: 20 additions & 0 deletions src/datetime/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1247,6 +1247,16 @@ impl<Tz: TimeZone> AddAssign<Duration> for DateTime<Tz> {
}
}

impl<Tz: TimeZone> Add<FixedOffset> for DateTime<Tz> {
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@pitdicker pitdicker Sep 25, 2023

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In my opinion this impl doesn't make much sense. Should the offset be added to the datetime, or to the offset? And why? I would like to remove it on main.

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@djc djc Sep 25, 2023

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Removing it on main sounds good to me.

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@pitdicker pitdicker Sep 25, 2023

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I'll make a PR soon-ish.

type Output = DateTime<Tz>;

#[inline]
fn add(mut self, rhs: FixedOffset) -> DateTime<Tz> {
self.datetime = self.naive_utc().checked_add_offset(rhs).unwrap();
self
}
}

impl<Tz: TimeZone> Add<Months> for DateTime<Tz> {
type Output = DateTime<Tz>;

Expand Down Expand Up @@ -1294,6 +1304,16 @@ impl<Tz: TimeZone> SubAssign<Duration> for DateTime<Tz> {
}
}

impl<Tz: TimeZone> Sub<FixedOffset> for DateTime<Tz> {
type Output = DateTime<Tz>;

#[inline]
fn sub(mut self, rhs: FixedOffset) -> DateTime<Tz> {
self.datetime = self.naive_utc().checked_sub_offset(rhs).unwrap();
self
}
}

impl<Tz: TimeZone> Sub<Months> for DateTime<Tz> {
type Output = DateTime<Tz>;

Expand Down
38 changes: 1 addition & 37 deletions src/offset/fixed.rs
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Expand Up @@ -4,17 +4,14 @@
//! The time zone which has a fixed offset from UTC.

use core::fmt;
use core::ops::{Add, Sub};
use core::str::FromStr;

#[cfg(feature = "rkyv")]
use rkyv::{Archive, Deserialize, Serialize};

use super::{LocalResult, Offset, TimeZone};
use crate::duration::Duration as OldDuration;
use crate::format::{scan, OUT_OF_RANGE};
use crate::format::{scan, ParseError, OUT_OF_RANGE};
use crate::naive::{NaiveDate, NaiveDateTime};
use crate::{DateTime, ParseError, Timelike};

/// The time zone with fixed offset, from UTC-23:59:59 to UTC+23:59:59.
///
Expand Down Expand Up @@ -184,39 +181,6 @@ impl arbitrary::Arbitrary<'_> for FixedOffset {
}
}

// addition or subtraction of FixedOffset to/from Timelike values is the same as
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// 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<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;
Expand Down