Struct tagged_pointer::TaggedPtr
source · [−]#[repr(transparent)]pub struct TaggedPtr<T, const BITS: usize>(_);
Expand description
A tagged pointer: a space-efficient representation of a pointer and integer tag.
This type stores a pointer and an integer tag without taking up more space than a normal pointer (unless the fallback implementation is used; see the crate documentation).
The tagged pointer conceptually holds a NonNull<T>
and a
certain number of bits of an integer tag.
BITS
specifies how many bits are used for the tag. The alignment of T
must be large enough to store this many bits; see Self::new
.
Implementations
sourceimpl<T, const BITS: usize> TaggedPtr<T, BITS>
impl<T, const BITS: usize> TaggedPtr<T, BITS>
sourcepub fn new(ptr: NonNull<T>, tag: usize) -> Self
pub fn new(ptr: NonNull<T>, tag: usize) -> Self
Creates a new tagged pointer. Only the lower BITS
bits of tag
are
stored.
Panics
This function panics if the alignment of T
is less than 2 to the
power of BITS
. This ensures that all properly aligned pointers to T
will be aligned enough to store the specified number of bits of the
tag.
ptr
should be “dereferencable” in the sense defined by
core::ptr
. If it is not, this function or methods
of TaggedPtr
may panic.
It is recommended that ptr
be properly aligned (i.e., aligned to at
least mem::align_of::<T>()
), but it may have a
smaller alignment. However, if its alignment is not at least
2 to the power of BITS
, this function may panic.
sourcepub fn get(self) -> (NonNull<T>, usize)
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.
Panics
If the pointer provided to Self::new
wasn’t
“dereferencable”, this method may panic.
sourcepub fn ptr(self) -> NonNull<T>
pub fn ptr(self) -> NonNull<T>
Gets the pointer stored by the tagged pointer, without the tag.
Equivalent to self.get().0
.
Panics
If the pointer provided to Self::new
wasn’t
“dereferencable”, this method may panic.
sourcepub fn tag(self) -> usize
pub fn tag(self) -> usize
Gets the tag stored by the tagged pointer. Equivalent to
self.get().1
.
Panics
If the pointer provided to Self::new
wasn’t
“dereferencable”, this method may panic.
Trait Implementations
sourceimpl<T, const BITS: usize> Ord for TaggedPtr<T, BITS>
impl<T, const BITS: usize> Ord for TaggedPtr<T, BITS>
sourceimpl<T, const BITS: usize> PartialOrd<TaggedPtr<T, BITS>> for TaggedPtr<T, BITS>
impl<T, const BITS: usize> PartialOrd<TaggedPtr<T, BITS>> for TaggedPtr<T, BITS>
sourcefn partial_cmp(&self, other: &Self) -> Option<Ordering>
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 · sourcefn lt(&self, other: &Rhs) -> bool
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 · sourcefn le(&self, other: &Rhs) -> bool
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
impl<T, const BITS: usize> Copy for TaggedPtr<T, BITS>
impl<T, const BITS: usize> Eq for TaggedPtr<T, BITS>
Auto Trait Implementations
impl<T, const BITS: usize> RefUnwindSafe for TaggedPtr<T, BITS> where
T: RefUnwindSafe,
impl<T, const BITS: usize> !Send for TaggedPtr<T, BITS>
impl<T, const BITS: usize> !Sync for TaggedPtr<T, BITS>
impl<T, const BITS: usize> Unpin for TaggedPtr<T, BITS>
impl<T, const BITS: usize> UnwindSafe for TaggedPtr<T, BITS> where
T: RefUnwindSafe,
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more