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add is_multiple_of for unsigned integer types
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folkertdev committed Jul 23, 2024
1 parent d111ccd commit aded725
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29 changes: 29 additions & 0 deletions library/core/src/num/uint_macros.rs
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Expand Up @@ -2764,6 +2764,35 @@ macro_rules! uint_impl {
}
}

/// Returns `true` if `self` is an integer multiple of `rhs`, and false otherwise.
///
/// This function is equivalent to `self % rhs == 0`, except that it will not panic
/// for `rhs == 0`. Instead, `0.is_multiple_of(0) == true`, and for any non-zero `n`,
/// `n.is_multiple_of(0) == false`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(unsigned_is_multiple_of)]
#[doc = concat!("assert!(6_", stringify!($SelfT), ".is_multiple_of(2));")]
#[doc = concat!("assert!(!5_", stringify!($SelfT), ".is_multiple_of(2));")]
///
#[doc = concat!("assert!(0_", stringify!($SelfT), ".is_multiple_of(0));")]
#[doc = concat!("assert!(!6_", stringify!($SelfT), ".is_multiple_of(0));")]
/// ```
#[unstable(feature = "unsigned_is_multiple_of", issue = "128101")]
#[must_use]
#[inline]
#[rustc_inherit_overflow_checks]
pub const fn is_multiple_of(self, rhs: Self) -> bool {
match rhs {
0 => self == 0,
_ => self % rhs == 0,
}
}

/// Returns `true` if and only if `self == 2^k` for some `k`.
///
/// # Examples
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1 change: 1 addition & 0 deletions library/core/tests/lib.rs
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Expand Up @@ -61,6 +61,7 @@
#![feature(num_midpoint)]
#![feature(offset_of_nested)]
#![feature(isqrt)]
#![feature(unsigned_is_multiple_of)]
#![feature(step_trait)]
#![feature(str_internals)]
#![feature(std_internals)]
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8 changes: 8 additions & 0 deletions library/core/tests/num/uint_macros.rs
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Expand Up @@ -260,6 +260,14 @@ macro_rules! uint_module {
assert_eq!(MAX.checked_next_multiple_of(2), None);
}

#[test]
fn test_is_next_multiple_of() {
assert!((12 as $T).is_multiple_of(4));
assert!(!(12 as $T).is_multiple_of(5));
assert!((0 as $T).is_multiple_of(0));
assert!(!(12 as $T).is_multiple_of(0));
}

#[test]
fn test_carrying_add() {
assert_eq!($T::MAX.carrying_add(1, false), (0, true));
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