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Add NonZero*::count_ones
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WaffleLapkin committed Jan 24, 2024
1 parent 5d3d347 commit e94d9a3
Showing 1 changed file with 37 additions and 0 deletions.
37 changes: 37 additions & 0 deletions library/core/src/num/nonzero.rs
Original file line number Diff line number Diff line change
Expand Up @@ -285,6 +285,43 @@ macro_rules! nonzero_integer {
unsafe { intrinsics::cttz_nonzero(self.get() as $UnsignedPrimitive) as u32 }
}
/// Returns the number of ones in the binary representation of `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(non_zero_count_ones)]
/// # fn main() { test().unwrap(); }
/// # fn test() -> Option<()> {
#[doc = concat!("# use std::num::{self, ", stringify!($Ty), "};")]
///
/// let one = num::NonZeroU32::new(1)?;
/// let three = num::NonZeroU32::new(3)?;
#[doc = concat!("let a = ", stringify!($Ty), "::new(0b100_0000)?;")]
#[doc = concat!("let b = ", stringify!($Ty), "::new(0b100_0011)?;")]
///
/// assert_eq!(a.count_ones(), one);
/// assert_eq!(b.count_ones(), three);
/// # Some(())
/// # }
/// ```
///
#[unstable(feature = "non_zero_count_ones", issue = "none")]
#[rustc_const_unstable(feature = "non_zero_count_ones", issue = "none")]
#[doc(alias = "popcount")]
#[doc(alias = "popcnt")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline(always)]
pub const fn count_ones(self) -> NonZeroU32 {
// SAFETY:
// `self` is non-zero, which means it has at least one bit set, which means
// that the result is non-zero.
unsafe { NonZeroU32::new_unchecked(self.get().count_ones()) }
}
nonzero_integer_signedness_dependent_methods! {
Self = $Ty,
Primitive = $signedness $Int,
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