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macro_rules! nonzero_integers {
( $( $Ty: ident($Int: ty); )+ ) => {
$(
/// An integer that is known not to equal zero.
///
/// This enables some memory layout optimization.
/// For example, `Option<NonZeroU32>` is the same size as `u32`:
///
/// ```rust
/// use std::mem::size_of;
/// assert_eq!(size_of::<Option<std::num::NonZeroU32>>(), size_of::<u32>());
/// ```
#[stable(feature = "nonzero", since = "1.28.0")]
// not all derive macros are implemented yet, and this test does not test these anyways
// #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
#[repr(transparent)]
pub struct $Ty(NonZero<$Int>);
impl $Ty {
/// Create a non-zero without checking the value.
///
/// # Safety
///
/// The value must not be zero.
#[stable(feature = "nonzero", since = "1.28.0")]
#[inline]
pub const unsafe fn new_unchecked(n: $Int) -> Self {
$Ty(NonZero(n))
}
/// Create a non-zero if the given value is not zero.
#[stable(feature = "nonzero", since = "1.28.0")]
#[inline]
pub fn new(n: $Int) -> Option<Self> {
if n != 0 {
Some($Ty(NonZero(n)))
} else {
None
}
}
/// Returns the value as a primitive type.
#[stable(feature = "nonzero", since = "1.28.0")]
#[inline]
pub fn get(self) -> $Int {
self.0 .0
}
}
impl_nonzero_fmt! { // { dg-error "unknown macro" }
(Debug, Display, Binary, Octal, LowerHex, UpperHex) for $Ty
}
)+
}
}
nonzero_integers! {
NonZeroU8(u8);
NonZeroU16(u16);
NonZeroU32(u32);
NonZeroU64(u64);
NonZeroU128(u128);
NonZeroUsize(usize);
}
|
