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Implement BITS constant for non-zero integers #93292

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Merged
merged 2 commits into from
Mar 13, 2022
Merged

Implement BITS constant for non-zero integers #93292

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1d13de6
Implement `BITS` constant for non-zero integers
nvzqz Mar 12, 2022
6b5acf0
Use `Self::BITS` in `log2` implementation
nvzqz Mar 12, 2022
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40 changes: 39 additions & 1 deletion library/core/src/num/nonzero.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -465,7 +465,7 @@ macro_rules! nonzero_unsigned_operations {
without modifying the original"]
#[inline]
pub const fn log2(self) -> u32 {
<$Int>::BITS - 1 - self.leading_zeros()
Self::BITS - 1 - self.leading_zeros()
}

/// Returns the base 10 logarithm of the number, rounded down.
Expand Down Expand Up @@ -1090,3 +1090,41 @@ nonzero_min_max_signed! {
NonZeroI128(i128);
NonZeroIsize(isize);
}

macro_rules! nonzero_bits {
( $( $Ty: ident($Int: ty); )+ ) => {
$(
impl $Ty {
/// The size of this non-zero integer type in bits.
///
#[doc = concat!("This value is equal to [`", stringify!($Int), "::BITS`].")]
///
/// # Examples
///
/// ```
/// #![feature(nonzero_bits)]
#[doc = concat!("# use std::num::", stringify!($Ty), ";")]
///
#[doc = concat!("assert_eq!(", stringify!($Ty), "::BITS, ", stringify!($Int), "::BITS);")]
/// ```
#[unstable(feature = "nonzero_bits", issue = "94881")]
pub const BITS: u32 = <$Int>::BITS;
}
)+
}
}

nonzero_bits! {
NonZeroU8(u8);
NonZeroI8(i8);
NonZeroU16(u16);
NonZeroI16(i16);
NonZeroU32(u32);
NonZeroI32(i32);
NonZeroU64(u64);
NonZeroI64(i64);
NonZeroU128(u128);
NonZeroI128(i128);
NonZeroUsize(usize);
NonZeroIsize(isize);
}