Skip to content

feat: implement CheckedNeg for Ratio #152

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
SAY-5 wants to merge 1 commit into
base: master
Choose a base branch
from
+30 −3
Open

feat: implement CheckedNeg for Ratio #152

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
33 changes: 30 additions & 3 deletions src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -39,8 +39,8 @@ use num_bigint::{BigInt, BigUint, Sign, ToBigInt};
use num_integer::Integer;
use num_traits::float::FloatCore;
use num_traits::{
Bounded, CheckedAdd, CheckedDiv, CheckedMul, CheckedSub, ConstOne, ConstZero, FromPrimitive,
Inv, Num, NumCast, One, Pow, Signed, ToPrimitive, Unsigned, Zero,
Bounded, CheckedAdd, CheckedDiv, CheckedMul, CheckedNeg, CheckedSub, ConstOne, ConstZero,
FromPrimitive, Inv, Num, NumCast, One, Pow, Signed, ToPrimitive, Unsigned, Zero,
};

mod pow;
Expand Down Expand Up @@ -876,6 +876,20 @@ checked_arith_impl!(impl CheckedAdd, checked_add);
// a/b - c/d = (lcm/b*a - lcm/d*c)/lcm, where lcm = lcm(b,d)
checked_arith_impl!(impl CheckedSub, checked_sub);

// -(a/b) = (-a)/b, so only the numerator can overflow
impl<T> CheckedNeg for Ratio<T>
where
T: Clone + Integer + CheckedNeg,
{
#[inline]
fn checked_neg(&self) -> Option<Ratio<T>> {
Some(Ratio::new_raw(
self.numer.checked_neg()?,
self.denom.clone(),
))
}
}

impl<T> Neg for Ratio<T>
where
T: Clone + Integer + Neg<Output = T>,
Expand Down Expand Up @@ -2151,7 +2165,9 @@ mod test {
use super::{to_big, _0, _1, _1_2, _2, _3_2, _5_2, _MAX, _MAX_M1, _MIN, _MIN_P1, _NEG1_2};
use core::fmt::Debug;
use num_integer::Integer;
use num_traits::{Bounded, CheckedAdd, CheckedDiv, CheckedMul, CheckedSub, NumAssign};
use num_traits::{
Bounded, CheckedAdd, CheckedDiv, CheckedMul, CheckedNeg, CheckedSub, NumAssign,
};

#[test]
fn test_add() {
Expand Down Expand Up @@ -2547,6 +2563,17 @@ mod test {
test(_1_2, _NEG1_2);
test(-_1, _1);
}

#[test]
fn test_checked_neg() {
assert_eq!(_0.checked_neg(), Some(_0));
assert_eq!(_1_2.checked_neg(), Some(_NEG1_2));
assert_eq!(_NEG1_2.checked_neg(), Some(_1_2));
// Negating the numerator i64::MIN overflows.
let min = Ratio::new(i64::MIN, 3);
assert_eq!(min.checked_neg(), None);
}

#[test]
#[allow(clippy::eq_op)]
fn test_zero() {
Expand Down