Struct TaggedPtr

pub struct TaggedPtr<T>(/* private fields */);

A tagged pointer with the maximum tag size for the given type.

This type behaves like crate::TaggedPtr but doesn’t have a BITS parameter that determines how many tag bits to store. Instead, this type uses the largest possible tag size for an aligned pointer to T; see Self::BITS for the exact calculation.

Unlike crate::TaggedPtr, this type always requires pointers to be properly aligned, even if you don’t need all the available tag bits; see Self::new.

Implementations

impl<T> TaggedPtr<T>

pub const BITS: u32

The number of tag bits that this tagged pointer can store. Equal to align_of::<T>().trailing_zeros() (because alignment is always a power of 2, this is the base-2 logarithm of the alignment of T).

pub const MAX_TAG: usize

The maximum tag (inclusive) that this tagged pointer can store. Equal to align_of::<T>() - 1.

pub fn new(ptr: NonNull<T>, tag: usize) -> Self

Creates a new tagged pointer. Only the lower Self::BITS bits of tag are stored.

Panics

This function may panic if ptr is not properly aligned (i.e., aligned to at least align_of::<T>()).

pub unsafe fn new_unchecked(ptr: NonNull<T>, tag: usize) -> Self

Equivalent to Self::new but without some runtime checks.

Safety

• ptr must be properly aligned (i.e., aligned to at least align_of::<T>()).
• tag cannot be greater than Self::MAX_TAG.

pub unsafe fn new_unchecked_dereferenceable(ptr: NonNull<T>, tag: usize) -> Self

Like Self::new_unchecked, but the pointer must be dereferenceable, which allows better optimization.

Safety

All conditions of Self::new_unchecked must be upheld, plus ptr must be “dereferenceable” in the sense defined by core::ptr.

impl<T> TaggedPtr<T>

pub fn get(self) -> (NonNull<T>, usize)

Gets the pointer and tag stored by the tagged pointer.

If you need both the pointer and tag, this method may be more efficient than calling Self::ptr and Self::tag separately.

pub fn ptr(self) -> NonNull<T>

Gets the pointer stored by the tagged pointer, without the tag. Equivalent to self.get().0.

pub fn set_ptr(&mut self, ptr: NonNull<T>)

Sets the pointer without modifying the tag.

This method is simply equivalent to:

*self = Self::new(ptr, self.tag());

See Self::new for information on argument validity and panics.

pub fn tag(self) -> usize

Gets the tag stored by the tagged pointer. Equivalent to self.get().1.

pub fn set_tag(&mut self, tag: usize)

Sets the tag without modifying the pointer.

This method is simply equivalent to:

*self = Self::new(self.ptr(), tag);

See Self::new for more information.

Trait Implementations

impl<T> Clone for TaggedPtr<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T> Debug for TaggedPtr<T>

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

Formats the value using the given formatter.

impl<T> Hash for TaggedPtr<T>

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

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<T> Ord for TaggedPtr<T>

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

Restrict a value to a certain interval.

impl<T> PartialEq for TaggedPtr<T>

fn eq(&self, other: &Self) -> 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<T> PartialOrd for TaggedPtr<T>

fn partial_cmp(&self, other: &Self) -> 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<T> Copy for TaggedPtr<T>

impl<T> Eq for TaggedPtr<T>