1 files changed, 137 insertions, 0 deletions
diff --git a/third_party/rust/num-traits/src/ops/saturating.rs b/third_party/rust/num-traits/src/ops/saturating.rs
new file mode 100644
index 0000000000..e39cfd7b6c
--- /dev/null
+++ b/third_party/rust/num-traits/src/ops/saturating.rs
@@ -0,0 +1,137 @@
+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);
+}