summaryrefslogtreecommitdiffstats
path: root/third_party/rust/num-traits/src/ops/euclid.rs
diff options
context:
space:
mode:
Diffstat (limited to 'third_party/rust/num-traits/src/ops/euclid.rs')
-rw-r--r--third_party/rust/num-traits/src/ops/euclid.rs347
1 files changed, 347 insertions, 0 deletions
diff --git a/third_party/rust/num-traits/src/ops/euclid.rs b/third_party/rust/num-traits/src/ops/euclid.rs
new file mode 100644
index 0000000000..99b51279f5
--- /dev/null
+++ b/third_party/rust/num-traits/src/ops/euclid.rs
@@ -0,0 +1,347 @@
+use core::ops::{Div, Rem};
+
+pub trait Euclid: Sized + Div<Self, Output = Self> + Rem<Self, Output = Self> {
+ /// Calculates Euclidean division, the matching method for `rem_euclid`.
+ ///
+ /// This computes the integer `n` such that
+ /// `self = n * v + self.rem_euclid(v)`.
+ /// In other words, the result is `self / v` rounded to the integer `n`
+ /// such that `self >= n * v`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use num_traits::Euclid;
+ ///
+ /// let a: i32 = 7;
+ /// let b: i32 = 4;
+ /// assert_eq!(Euclid::div_euclid(&a, &b), 1); // 7 > 4 * 1
+ /// assert_eq!(Euclid::div_euclid(&-a, &b), -2); // -7 >= 4 * -2
+ /// assert_eq!(Euclid::div_euclid(&a, &-b), -1); // 7 >= -4 * -1
+ /// assert_eq!(Euclid::div_euclid(&-a, &-b), 2); // -7 >= -4 * 2
+ /// ```
+ fn div_euclid(&self, v: &Self) -> Self;
+
+ /// Calculates the least nonnegative remainder of `self (mod v)`.
+ ///
+ /// In particular, the return value `r` satisfies `0.0 <= r < v.abs()` in
+ /// most cases. However, due to a floating point round-off error it can
+ /// result in `r == v.abs()`, violating the mathematical definition, if
+ /// `self` is much smaller than `v.abs()` in magnitude and `self < 0.0`.
+ /// This result is not an element of the function's codomain, but it is the
+ /// closest floating point number in the real numbers and thus fulfills the
+ /// property `self == self.div_euclid(v) * v + self.rem_euclid(v)`
+ /// approximatively.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use num_traits::Euclid;
+ ///
+ /// let a: i32 = 7;
+ /// let b: i32 = 4;
+ /// assert_eq!(Euclid::rem_euclid(&a, &b), 3);
+ /// assert_eq!(Euclid::rem_euclid(&-a, &b), 1);
+ /// assert_eq!(Euclid::rem_euclid(&a, &-b), 3);
+ /// assert_eq!(Euclid::rem_euclid(&-a, &-b), 1);
+ /// ```
+ fn rem_euclid(&self, v: &Self) -> Self;
+}
+
+macro_rules! euclid_forward_impl {
+ ($($t:ty)*) => {$(
+ #[cfg(has_div_euclid)]
+ impl Euclid for $t {
+ #[inline]
+ fn div_euclid(&self, v: &$t) -> Self {
+ <$t>::div_euclid(*self, *v)
+ }
+
+ #[inline]
+ fn rem_euclid(&self, v: &$t) -> Self {
+ <$t>::rem_euclid(*self, *v)
+ }
+ }
+ )*}
+}
+
+macro_rules! euclid_int_impl {
+ ($($t:ty)*) => {$(
+ euclid_forward_impl!($t);
+
+ #[cfg(not(has_div_euclid))]
+ impl Euclid for $t {
+ #[inline]
+ fn div_euclid(&self, v: &$t) -> Self {
+ let q = self / v;
+ if self % v < 0 {
+ return if *v > 0 { q - 1 } else { q + 1 }
+ }
+ q
+ }
+
+ #[inline]
+ fn rem_euclid(&self, v: &$t) -> Self {
+ let r = self % v;
+ if r < 0 {
+ if *v < 0 {
+ r - v
+ } else {
+ r + v
+ }
+ } else {
+ r
+ }
+ }
+ }
+ )*}
+}
+
+macro_rules! euclid_uint_impl {
+ ($($t:ty)*) => {$(
+ euclid_forward_impl!($t);
+
+ #[cfg(not(has_div_euclid))]
+ impl Euclid for $t {
+ #[inline]
+ fn div_euclid(&self, v: &$t) -> Self {
+ self / v
+ }
+
+ #[inline]
+ fn rem_euclid(&self, v: &$t) -> Self {
+ self % v
+ }
+ }
+ )*}
+}
+
+euclid_int_impl!(isize i8 i16 i32 i64);
+euclid_uint_impl!(usize u8 u16 u32 u64);
+#[cfg(has_i128)]
+euclid_int_impl!(i128);
+#[cfg(has_i128)]
+euclid_uint_impl!(u128);
+
+#[cfg(all(has_div_euclid, feature = "std"))]
+euclid_forward_impl!(f32 f64);
+
+#[cfg(not(all(has_div_euclid, feature = "std")))]
+impl Euclid for f32 {
+ #[inline]
+ fn div_euclid(&self, v: &f32) -> f32 {
+ let q = <f32 as ::float::FloatCore>::trunc(self / v);
+ if self % v < 0.0 {
+ return if *v > 0.0 { q - 1.0 } else { q + 1.0 };
+ }
+ q
+ }
+
+ #[inline]
+ fn rem_euclid(&self, v: &f32) -> f32 {
+ let r = self % v;
+ if r < 0.0 {
+ r + <f32 as ::float::FloatCore>::abs(*v)
+ } else {
+ r
+ }
+ }
+}
+
+#[cfg(not(all(has_div_euclid, feature = "std")))]
+impl Euclid for f64 {
+ #[inline]
+ fn div_euclid(&self, v: &f64) -> f64 {
+ let q = <f64 as ::float::FloatCore>::trunc(self / v);
+ if self % v < 0.0 {
+ return if *v > 0.0 { q - 1.0 } else { q + 1.0 };
+ }
+ q
+ }
+
+ #[inline]
+ fn rem_euclid(&self, v: &f64) -> f64 {
+ let r = self % v;
+ if r < 0.0 {
+ r + <f64 as ::float::FloatCore>::abs(*v)
+ } else {
+ r
+ }
+ }
+}
+
+pub trait CheckedEuclid: Euclid {
+ /// Performs euclid division that returns `None` instead of panicking on division by zero
+ /// and instead of wrapping around on underflow and overflow.
+ fn checked_div_euclid(&self, v: &Self) -> Option<Self>;
+
+ /// Finds the euclid remainder of dividing two numbers, checking for underflow, overflow and
+ /// division by zero. If any of that happens, `None` is returned.
+ fn checked_rem_euclid(&self, v: &Self) -> Option<Self>;
+}
+
+macro_rules! checked_euclid_forward_impl {
+ ($($t:ty)*) => {$(
+ #[cfg(has_div_euclid)]
+ impl CheckedEuclid for $t {
+ #[inline]
+ fn checked_div_euclid(&self, v: &$t) -> Option<Self> {
+ <$t>::checked_div_euclid(*self, *v)
+ }
+
+ #[inline]
+ fn checked_rem_euclid(&self, v: &$t) -> Option<Self> {
+ <$t>::checked_rem_euclid(*self, *v)
+ }
+ }
+ )*}
+}
+
+macro_rules! checked_euclid_int_impl {
+ ($($t:ty)*) => {$(
+ checked_euclid_forward_impl!($t);
+
+ #[cfg(not(has_div_euclid))]
+ impl CheckedEuclid for $t {
+ #[inline]
+ fn checked_div_euclid(&self, v: &$t) -> Option<$t> {
+ if *v == 0 || (*self == Self::min_value() && *v == -1) {
+ None
+ } else {
+ Some(Euclid::div_euclid(self, v))
+ }
+ }
+
+ #[inline]
+ fn checked_rem_euclid(&self, v: &$t) -> Option<$t> {
+ if *v == 0 || (*self == Self::min_value() && *v == -1) {
+ None
+ } else {
+ Some(Euclid::rem_euclid(self, v))
+ }
+ }
+ }
+ )*}
+}
+
+macro_rules! checked_euclid_uint_impl {
+ ($($t:ty)*) => {$(
+ checked_euclid_forward_impl!($t);
+
+ #[cfg(not(has_div_euclid))]
+ impl CheckedEuclid for $t {
+ #[inline]
+ fn checked_div_euclid(&self, v: &$t) -> Option<$t> {
+ if *v == 0 {
+ None
+ } else {
+ Some(Euclid::div_euclid(self, v))
+ }
+ }
+
+ #[inline]
+ fn checked_rem_euclid(&self, v: &$t) -> Option<$t> {
+ if *v == 0 {
+ None
+ } else {
+ Some(Euclid::rem_euclid(self, v))
+ }
+ }
+ }
+ )*}
+}
+
+checked_euclid_int_impl!(isize i8 i16 i32 i64);
+checked_euclid_uint_impl!(usize u8 u16 u32 u64);
+#[cfg(has_i128)]
+checked_euclid_int_impl!(i128);
+#[cfg(has_i128)]
+checked_euclid_uint_impl!(u128);
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn euclid_unsigned() {
+ macro_rules! test_euclid {
+ ($($t:ident)+) => {
+ $(
+ {
+ let x: $t = 10;
+ let y: $t = 3;
+ assert_eq!(Euclid::div_euclid(&x, &y), 3);
+ assert_eq!(Euclid::rem_euclid(&x, &y), 1);
+ }
+ )+
+ };
+ }
+
+ test_euclid!(usize u8 u16 u32 u64);
+ }
+
+ #[test]
+ fn euclid_signed() {
+ macro_rules! test_euclid {
+ ($($t:ident)+) => {
+ $(
+ {
+ let x: $t = 10;
+ let y: $t = -3;
+ assert_eq!(Euclid::div_euclid(&x, &y), -3);
+ assert_eq!(Euclid::div_euclid(&-x, &y), 4);
+ assert_eq!(Euclid::rem_euclid(&x, &y), 1);
+ assert_eq!(Euclid::rem_euclid(&-x, &y), 2);
+ let x: $t = $t::min_value() + 1;
+ let y: $t = -1;
+ assert_eq!(Euclid::div_euclid(&x, &y), $t::max_value());
+ }
+ )+
+ };
+ }
+
+ test_euclid!(isize i8 i16 i32 i64);
+ }
+
+ #[test]
+ fn euclid_float() {
+ macro_rules! test_euclid {
+ ($($t:ident)+) => {
+ $(
+ {
+ let x: $t = 12.1;
+ let y: $t = 3.2;
+ assert!(Euclid::div_euclid(&x, &y) * y + Euclid::rem_euclid(&x, &y) - x
+ <= 46.4 * <$t as ::float::FloatCore>::epsilon());
+ assert!(Euclid::div_euclid(&x, &-y) * -y + Euclid::rem_euclid(&x, &-y) - x
+ <= 46.4 * <$t as ::float::FloatCore>::epsilon());
+ assert!(Euclid::div_euclid(&-x, &y) * y + Euclid::rem_euclid(&-x, &y) + x
+ <= 46.4 * <$t as ::float::FloatCore>::epsilon());
+ assert!(Euclid::div_euclid(&-x, &-y) * -y + Euclid::rem_euclid(&-x, &-y) + x
+ <= 46.4 * <$t as ::float::FloatCore>::epsilon());
+ }
+ )+
+ };
+ }
+
+ test_euclid!(f32 f64);
+ }
+
+ #[test]
+ fn euclid_checked() {
+ macro_rules! test_euclid_checked {
+ ($($t:ident)+) => {
+ $(
+ {
+ assert_eq!(CheckedEuclid::checked_div_euclid(&$t::min_value(), &-1), None);
+ assert_eq!(CheckedEuclid::checked_rem_euclid(&$t::min_value(), &-1), None);
+ assert_eq!(CheckedEuclid::checked_div_euclid(&1, &0), None);
+ assert_eq!(CheckedEuclid::checked_rem_euclid(&1, &0), None);
+ }
+ )+
+ };
+ }
+
+ test_euclid_checked!(isize i8 i16 i32 i64);
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-26 14:30:05 +0000