Struct serde::lib::ptr::Alignment

#[repr(transparent)]
pub struct Alignment(AlignmentEnum);

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

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.

Tuple Fields

0: AlignmentEnum

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

Implementations

impl Alignment

pub const MIN: Alignment = _

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

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);

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

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

Returns the alignment for a type.

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

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

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

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.

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

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

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.

pub const fn as_usize(self) -> usize

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

Returns the alignment as a usize.

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

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

Returns the alignment as a NonZero<usize>.

pub const fn log2(self) -> u32

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

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);

pub const fn mask(self) -> usize

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

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);

Trait Implementations

impl Clone for Alignment

fn clone(&self) -> Alignment

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Alignment

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

Formats the value using the given formatter.

impl Default for Alignment

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

fn default() -> Alignment

Returns the “default value” for a type.

impl From<Alignment> for NonZero<usize>

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

Converts to this type from the input type.

impl From<Alignment> for usize

fn from(align: Alignment) -> usize

Converts to this type from the input type.

impl Hash for Alignment

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

where H: Hasher,

Feeds this value into the given Hasher.

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

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Alignment

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

This method returns an Ordering between self and other.

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

where Self: Sized,

Compares and returns the maximum of two values.

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

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized + PartialOrd,

Restrict a value to a certain interval.

impl PartialEq for Alignment

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Alignment

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

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl TryFrom<NonZero<usize>> for Alignment

type Error = TryFromIntError

The type returned in the event of a conversion error.

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

Performs the conversion.

impl TryFrom<usize> for Alignment

type Error = TryFromIntError

The type returned in the event of a conversion error.

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

Performs the conversion.

impl Copy for Alignment

impl Eq for Alignment

impl StructuralPartialEq for Alignment