Struct core::ptr::Alignment

source ·
pub struct Alignment(/* private fields */);
🔬This is a nightly-only experimental API. (ptr_alignment_type #102070)
Expand description

A type storing a usize which is a power of two, and thus represents a possible alignment in the Rust abstract machine.

Note that particularly large alignments, while representable in this type, are likely not to be supported by actual allocators and linkers.

Implementations§

source§

impl Alignment

source

pub const MIN: Self = _

🔬This is a nightly-only experimental API. (ptr_alignment_type #102070)

The smallest possible alignment, 1.

All addresses are always aligned at least this much.

§Examples
#![feature(ptr_alignment_type)]
use std::ptr::Alignment;

assert_eq!(Alignment::MIN.as_usize(), 1);
Run
source

pub const fn of<T>() -> Self

🔬This is a nightly-only experimental API. (ptr_alignment_type #102070)

Returns the alignment for a type.

This provides the same numerical value as mem::align_of, but in an Alignment instead of a usize.

source

pub const fn new(align: usize) -> Option<Self>

🔬This is a nightly-only experimental API. (ptr_alignment_type #102070)

Creates an Alignment from a usize, or returns None if it’s not a power of two.

Note that 0 is not a power of two, nor a valid alignment.

source

pub const unsafe fn new_unchecked(align: usize) -> Self

🔬This is a nightly-only experimental API. (ptr_alignment_type #102070)

Creates an Alignment from a power-of-two usize.

§Safety

align must be a power of two.

Equivalently, it must be 1 << exp for some exp in 0..usize::BITS. It must not be zero.

source

pub const fn as_usize(self) -> usize

🔬This is a nightly-only experimental API. (ptr_alignment_type #102070)

Returns the alignment as a usize.

source

pub const fn as_nonzero(self) -> NonZero<usize>

🔬This is a nightly-only experimental API. (ptr_alignment_type #102070)

Returns the alignment as a NonZero<usize>.

source

pub const fn log2(self) -> u32

🔬This is a nightly-only experimental API. (ptr_alignment_type #102070)

Returns the base-2 logarithm of the alignment.

This is always exact, as self represents a power of two.

§Examples
#![feature(ptr_alignment_type)]
use std::ptr::Alignment;

assert_eq!(Alignment::of::<u8>().log2(), 0);
assert_eq!(Alignment::new(1024).unwrap().log2(), 10);
Run
source

pub const fn mask(self) -> usize

🔬This is a nightly-only experimental API. (ptr_alignment_type #102070)

Returns a bit mask that can be used to match this alignment.

This is equivalent to !(self.as_usize() - 1).

§Examples
#![feature(ptr_alignment_type)]
#![feature(ptr_mask)]
use std::ptr::{Alignment, NonNull};

#[repr(align(1))] struct Align1(u8);
#[repr(align(2))] struct Align2(u16);
#[repr(align(4))] struct Align4(u32);
let one = <NonNull<Align1>>::dangling().as_ptr();
let two = <NonNull<Align2>>::dangling().as_ptr();
let four = <NonNull<Align4>>::dangling().as_ptr();

assert_eq!(four.mask(Alignment::of::<Align1>().mask()), four);
assert_eq!(four.mask(Alignment::of::<Align2>().mask()), four);
assert_eq!(four.mask(Alignment::of::<Align4>().mask()), four);
assert_ne!(one.mask(Alignment::of::<Align4>().mask()), one);
Run

Trait Implementations§

source§

impl Clone for Alignment

source§

fn clone(&self) -> Alignment

Returns a copy of the value. Read more
1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
source§

impl Debug for Alignment

source§

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
source§

impl Default for Alignment

Returns Alignment::MIN, which is valid for any type.

source§

fn default() -> Alignment

Returns the “default value” for a type. Read more
source§

impl From<Alignment> for NonZero<usize>

source§

fn from(align: Alignment) -> NonZero<usize>

Converts to this type from the input type.
source§

impl From<Alignment> for usize

source§

fn from(align: Alignment) -> usize

Converts to this type from the input type.
source§

impl Hash for Alignment

source§

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher. Read more
1.3.0 · source§

fn hash_slice<H: Hasher>(data: &[Self], state: &mut H)
where Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
source§

impl Ord for Alignment

source§

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other. Read more
1.21.0 · source§

fn max(self, other: Self) -> Self
where Self: Sized,

Compares and returns the maximum of two values. Read more
1.21.0 · source§

fn min(self, other: Self) -> Self
where Self: Sized,

Compares and returns the minimum of two values. Read more
1.50.0 · source§

fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
source§

impl PartialEq for Alignment

source§

fn eq(&self, other: &Alignment) -> bool

This method tests for self and other values to be equal, and is used by ==.
1.0.0 · source§

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
source§

impl PartialOrd for Alignment

source§

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
source§

impl TryFrom<NonZero<usize>> for Alignment

§

type Error = TryFromIntError

The type returned in the event of a conversion error.
source§

fn try_from(align: NonZero<usize>) -> Result<Alignment, Self::Error>

Performs the conversion.
source§

impl TryFrom<usize> for Alignment

§

type Error = TryFromIntError

The type returned in the event of a conversion error.
source§

fn try_from(align: usize) -> Result<Alignment, Self::Error>

Performs the conversion.
source§

impl Copy for Alignment

source§

impl Eq for Alignment

source§

impl StructuralPartialEq for Alignment

Auto Trait Implementations§

Blanket Implementations§

source§

impl<T> Any for T
where T: 'static + ?Sized,

source§

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
source§

impl<T> Borrow<T> for T
where T: ?Sized,

source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
source§

impl<T> BorrowMut<T> for T
where T: ?Sized,

source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
source§

impl<T> CloneToUninit for T
where T: Clone,

source§

default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit #126799)
Performs copy-assignment from self to dst. Read more
source§

impl<T> CloneToUninit for T
where T: Copy,

source§

unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit #126799)
Performs copy-assignment from self to dst. Read more
source§

impl<T> From<T> for T

source§

fn from(t: T) -> T

Returns the argument unchanged.

source§

impl<T, U> Into<U> for T
where U: From<T>,

source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

source§

impl<T, U> TryFrom<U> for T
where U: Into<T>,

§

type Error = Infallible

The type returned in the event of a conversion error.
source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
source§

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

§

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.