Merge pull request #256 from nwin/add-wrapping-traits

Added traits for wrapping arithmetics.
This commit is contained in:
Josh Stone 2017-02-04 21:47:53 -08:00 committed by GitHub
commit 817ab00f64
3 changed files with 90 additions and 0 deletions

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@ -20,6 +20,7 @@ pub use bounds::Bounded;
pub use float::{Float, FloatConst}; pub use float::{Float, FloatConst};
pub use identities::{Zero, One, zero, one}; pub use identities::{Zero, One, zero, one};
pub use ops::checked::*; pub use ops::checked::*;
pub use ops::wrapping::*;
pub use ops::saturating::Saturating; pub use ops::saturating::Saturating;
pub use sign::{Signed, Unsigned, abs, abs_sub, signum}; pub use sign::{Signed, Unsigned, abs, abs_sub, signum};
pub use cast::*; pub use cast::*;

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@ -1,2 +1,3 @@
pub mod saturating; pub mod saturating;
pub mod checked; pub mod checked;
pub mod wrapping;

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@ -0,0 +1,88 @@
use std::ops::{Add, Sub, Mul};
macro_rules! wrapping_impl {
($trait_name:ident, $method:ident, $t:ty) => {
impl $trait_name for $t {
#[inline]
fn $method(&self, v: &Self) -> Self {
<$t>::$method(*self, *v)
}
}
};
($trait_name:ident, $method:ident, $t:ty, $rhs:ty) => {
impl $trait_name<$rhs> for $t {
#[inline]
fn $method(&self, v: &$rhs) -> Self {
<$t>::$method(*self, *v)
}
}
}
}
/// Performs addition that wraps around on overflow.
pub trait WrappingAdd: Sized + Add<Self, Output=Self> {
/// Wrapping (modular) addition. Computes `self + other`, wrapping around at the boundary of
/// the type.
fn wrapping_add(&self, v: &Self) -> Self;
}
wrapping_impl!(WrappingAdd, wrapping_add, u8);
wrapping_impl!(WrappingAdd, wrapping_add, u16);
wrapping_impl!(WrappingAdd, wrapping_add, u32);
wrapping_impl!(WrappingAdd, wrapping_add, u64);
wrapping_impl!(WrappingAdd, wrapping_add, usize);
wrapping_impl!(WrappingAdd, wrapping_add, i8);
wrapping_impl!(WrappingAdd, wrapping_add, i16);
wrapping_impl!(WrappingAdd, wrapping_add, i32);
wrapping_impl!(WrappingAdd, wrapping_add, i64);
wrapping_impl!(WrappingAdd, wrapping_add, isize);
/// Performs subtraction that wraps around on overflow.
pub trait WrappingSub: Sized + Sub<Self, Output=Self> {
/// Wrapping (modular) subtraction. Computes `self - other`, wrapping around at the boundary
/// of the type.
fn wrapping_sub(&self, v: &Self) -> Self;
}
wrapping_impl!(WrappingSub, wrapping_sub, u8);
wrapping_impl!(WrappingSub, wrapping_sub, u16);
wrapping_impl!(WrappingSub, wrapping_sub, u32);
wrapping_impl!(WrappingSub, wrapping_sub, u64);
wrapping_impl!(WrappingSub, wrapping_sub, usize);
wrapping_impl!(WrappingSub, wrapping_sub, i8);
wrapping_impl!(WrappingSub, wrapping_sub, i16);
wrapping_impl!(WrappingSub, wrapping_sub, i32);
wrapping_impl!(WrappingSub, wrapping_sub, i64);
wrapping_impl!(WrappingSub, wrapping_sub, isize);
/// Performs multiplication that wraps around on overflow.
pub trait WrappingMul: Sized + Mul<Self, Output=Self> {
/// Wrapping (modular) multiplication. Computes `self * other`, wrapping around at the boundary
/// of the type.
fn wrapping_mul(&self, v: &Self) -> Self;
}
wrapping_impl!(WrappingMul, wrapping_mul, u8);
wrapping_impl!(WrappingMul, wrapping_mul, u16);
wrapping_impl!(WrappingMul, wrapping_mul, u32);
wrapping_impl!(WrappingMul, wrapping_mul, u64);
wrapping_impl!(WrappingMul, wrapping_mul, usize);
wrapping_impl!(WrappingMul, wrapping_mul, i8);
wrapping_impl!(WrappingMul, wrapping_mul, i16);
wrapping_impl!(WrappingMul, wrapping_mul, i32);
wrapping_impl!(WrappingMul, wrapping_mul, i64);
wrapping_impl!(WrappingMul, wrapping_mul, isize);
#[test]
fn test_wrapping_traits() {
fn wrapping_add<T: WrappingAdd>(a: T, b: T) -> T { a.wrapping_add(&b) }
fn wrapping_sub<T: WrappingSub>(a: T, b: T) -> T { a.wrapping_sub(&b) }
fn wrapping_mul<T: WrappingMul>(a: T, b: T) -> T { a.wrapping_mul(&b) }
assert_eq!(wrapping_add(255, 1), 0u8);
assert_eq!(wrapping_sub(0, 1), 255u8);
assert_eq!(wrapping_mul(255, 2), 254u8);
}