saturating.rs - source
Description: Source of the Rust file `/Users/erlendbasso/.cargo/registry/src/github.com-1ecc6299db9ec823/num-traits-0.2.15/src/ops/saturating.rs`.
Keywords: rust, rustlang, rust-lang

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    use core::ops::{Add, Mul, Sub};

    /// Saturating math operations. Deprecated, use `SaturatingAdd`, `SaturatingSub` and
    /// `SaturatingMul` instead.
    pub trait Saturating {
        /// Saturating addition operator.
        /// Returns a+b, saturating at the numeric bounds instead of overflowing.
        fn saturating_add(self, v: Self) -> Self;

        /// Saturating subtraction operator.
        /// Returns a-b, saturating at the numeric bounds instead of overflowing.
        fn saturating_sub(self, v: Self) -> Self;
    }

    macro_rules! deprecated_saturating_impl {
        ($trait_name:ident for $($t:ty)*) => {$(
            impl $trait_name for $t {
                #[inline]
                fn saturating_add(self, v: Self) -> Self {
                    Self::saturating_add(self, v)
                }

                #[inline]
                fn saturating_sub(self, v: Self) -> Self {
                    Self::saturating_sub(self, v)
                }
            }
        )*}
    }

    deprecated_saturating_impl!(Saturating for isize usize i8 u8 i16 u16 i32 u32 i64 u64);
    #[cfg(has_i128)]
    deprecated_saturating_impl!(Saturating for i128 u128);

    macro_rules! saturating_impl {
        ($trait_name:ident, $method:ident, $t:ty) => {
            impl $trait_name for $t {
                #[inline]
                fn $method(&self, v: &Self) -> Self {
                    <$t>::$method(*self, *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
        /// the type.
        fn saturating_add(&self, v: &Self) -> Self;
    }

    saturating_impl!(SaturatingAdd, saturating_add, u8);
    saturating_impl!(SaturatingAdd, saturating_add, u16);
    saturating_impl!(SaturatingAdd, saturating_add, u32);
    saturating_impl!(SaturatingAdd, saturating_add, u64);
    saturating_impl!(SaturatingAdd, saturating_add, usize);
    #[cfg(has_i128)]
    saturating_impl!(SaturatingAdd, saturating_add, u128);

    saturating_impl!(SaturatingAdd, saturating_add, i8);
    saturating_impl!(SaturatingAdd, saturating_add, i16);
    saturating_impl!(SaturatingAdd, saturating_add, i32);
    saturating_impl!(SaturatingAdd, saturating_add, i64);
    saturating_impl!(SaturatingAdd, saturating_add, isize);
    #[cfg(has_i128)]
    saturating_impl!(SaturatingAdd, saturating_add, i128);

    /// 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
        /// the type.
        fn saturating_sub(&self, v: &Self) -> Self;
    }

    saturating_impl!(SaturatingSub, saturating_sub, u8);
    saturating_impl!(SaturatingSub, saturating_sub, u16);
    saturating_impl!(SaturatingSub, saturating_sub, u32);
    saturating_impl!(SaturatingSub, saturating_sub, u64);
    saturating_impl!(SaturatingSub, saturating_sub, usize);
    #[cfg(has_i128)]
    saturating_impl!(SaturatingSub, saturating_sub, u128);

    saturating_impl!(SaturatingSub, saturating_sub, i8);
    saturating_impl!(SaturatingSub, saturating_sub, i16);
    saturating_impl!(SaturatingSub, saturating_sub, i32);
    saturating_impl!(SaturatingSub, saturating_sub, i64);
    saturating_impl!(SaturatingSub, saturating_sub, isize);
    #[cfg(has_i128)]
    saturating_impl!(SaturatingSub, saturating_sub, i128);

    /// 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
        /// the type.
        fn saturating_mul(&self, v: &Self) -> Self;
    }

    saturating_impl!(SaturatingMul, saturating_mul, u8);
    saturating_impl!(SaturatingMul, saturating_mul, u16);
    saturating_impl!(SaturatingMul, saturating_mul, u32);
    saturating_impl!(SaturatingMul, saturating_mul, u64);
    saturating_impl!(SaturatingMul, saturating_mul, usize);
    #[cfg(has_i128)]
    saturating_impl!(SaturatingMul, saturating_mul, u128);

    saturating_impl!(SaturatingMul, saturating_mul, i8);
    saturating_impl!(SaturatingMul, saturating_mul, i16);
    saturating_impl!(SaturatingMul, saturating_mul, i32);
    saturating_impl!(SaturatingMul, saturating_mul, i64);
    saturating_impl!(SaturatingMul, saturating_mul, isize);
    #[cfg(has_i128)]
    saturating_impl!(SaturatingMul, saturating_mul, i128);

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

    #[test]
    fn test_saturating_traits() {
        fn saturating_add<T: SaturatingAdd>(a: T, b: T) -> T {
            a.saturating_add(&b)
        }
        fn saturating_sub<T: SaturatingSub>(a: T, b: T) -> T {
            a.saturating_sub(&b)
        }
        fn saturating_mul<T: SaturatingMul>(a: T, b: T) -> T {
            a.saturating_mul(&b)
        }
        assert_eq!(saturating_add(255, 1), 255u8);
        assert_eq!(saturating_add(127, 1), 127i8);
        assert_eq!(saturating_add(-128, -1), -128i8);
        assert_eq!(saturating_sub(0, 1), 0u8);
        assert_eq!(saturating_sub(-128, 1), -128i8);
        assert_eq!(saturating_sub(127, -1), 127i8);
        assert_eq!(saturating_mul(255, 2), 255u8);
        assert_eq!(saturating_mul(127, 2), 127i8);
        assert_eq!(saturating_mul(-128, 2), -128i8);
    }