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Ops: Add Saturating ops for floating point numbers #362

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Ops: Add Saturating ops for floating point numbers #362

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28 changes: 28 additions & 0 deletions src/ops/saturating.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,17 @@ macro_rules! saturating_impl {
};
}

macro_rules! float_saturating_impl {
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@Dietr1ch Dietr1ch May 28, 2025 •
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Well, this is not specific to floats, but it doesn't seem to be useful for other types yet and it requires that the type is naturally saturating.

($trait_name:ident, $method_name:ident, $t:ty, $method:ident) => {
impl $trait_name for $t {
#[inline]
fn $method_name(&self, v: &Self) -> Self {
self.$method(v)
}
}
};
}

/// Performs addition that saturates at the numeric bounds instead of overflowing.
pub trait SaturatingAdd: Sized + Add<Self, Output = Self> {
/// Saturating addition. Computes `self + other`, saturating at the relevant high or low boundary of
Expand All @@ -63,6 +74,9 @@ saturating_impl!(SaturatingAdd, saturating_add, i64);
saturating_impl!(SaturatingAdd, saturating_add, isize);
saturating_impl!(SaturatingAdd, saturating_add, i128);

float_saturating_impl!(SaturatingAdd, saturating_add, f32, add);
float_saturating_impl!(SaturatingAdd, saturating_add, f64, add);

/// Performs subtraction that saturates at the numeric bounds instead of overflowing.
pub trait SaturatingSub: Sized + Sub<Self, Output = Self> {
/// Saturating subtraction. Computes `self - other`, saturating at the relevant high or low boundary of
Expand All @@ -84,6 +98,9 @@ saturating_impl!(SaturatingSub, saturating_sub, i64);
saturating_impl!(SaturatingSub, saturating_sub, isize);
saturating_impl!(SaturatingSub, saturating_sub, i128);

float_saturating_impl!(SaturatingSub, saturating_sub, f32, sub);
float_saturating_impl!(SaturatingSub, saturating_sub, f64, sub);

/// Performs multiplication that saturates at the numeric bounds instead of overflowing.
pub trait SaturatingMul: Sized + Mul<Self, Output = Self> {
/// Saturating multiplication. Computes `self * other`, saturating at the relevant high or low boundary of
Expand All @@ -105,6 +122,9 @@ saturating_impl!(SaturatingMul, saturating_mul, i64);
saturating_impl!(SaturatingMul, saturating_mul, isize);
saturating_impl!(SaturatingMul, saturating_mul, i128);

float_saturating_impl!(SaturatingMul, saturating_mul, f32, mul);
float_saturating_impl!(SaturatingMul, saturating_mul, f64, mul);

// TODO: add SaturatingNeg for signed integer primitives once the saturating_neg() API is stable.

#[test]
Expand All @@ -118,13 +138,21 @@ fn test_saturating_traits() {
fn saturating_mul<T: SaturatingMul>(a: T, b: T) -> T {
a.saturating_mul(&b)
}

const INF: f32 = f32::INFINITY;
assert_eq!(saturating_add(255, 1), 255u8);
assert_eq!(saturating_add(127, 1), 127i8);
assert_eq!(saturating_add(-128, -1), -128i8);
assert_eq!(saturating_add(100.0, INF), INF);

assert_eq!(saturating_sub(0, 1), 0u8);
assert_eq!(saturating_sub(-128, 1), -128i8);
assert_eq!(saturating_sub(127, -1), 127i8);
assert_eq!(saturating_sub(100.0, INF), -INF);

assert_eq!(saturating_mul(255, 2), 255u8);
assert_eq!(saturating_mul(127, 2), 127i8);
assert_eq!(saturating_mul(-128, 2), -128i8);
assert_eq!(saturating_mul(100.0, INF), INF);
assert_eq!(saturating_mul(-100.0, INF), -INF);
}