Struct thinbox::ThinBox

pub struct ThinBox<T: ?Sized> { /* fields omitted */ }

A consistently-sized pointer type for heap allocation.

See the crate documentation for an example using ThinBox.

Implementations

impl<T: ?Sized> ThinBox<T>

pub fn unsize<U: Unsize<T>>(value: U) -> Self

Creates a new ThinBox by unsizing a value and placing it on the heap.

pub unsafe fn from_raw(raw: *mut ()) -> Self

Recovers ThinBox ownership of a pointee.

Safety

• raw must be result of Box::<U>::into_raw as *mut () or ThinBox::<U>::into_raw where U safe to transmute into T.
• The alignment requirements of T must not be more strict than those of U.
• It must be generally safe to dereference raw, keeping in mind that raw does not actually point to () and does not necessarily even point to a U.

The first requirement implies that:

• U: Sized and/or U is T.
• raw is neither null nor dangling.

Furthermore, support for Box::<U>::into_raw is not guaranteed to be preserved across major versions of thinbox.

pub fn into_raw(thin: Self) -> *mut ()

Converts the ThinBox to a single-pointer-sized representation.

Notes

It is not safe to dereference this representation. The type of the pointee depends not only on T but also on whether or not T is unsized.

pub fn as_ptr(thin: &Self) -> *mut T

Obtains a raw pointer to the boxed value.

The pointee remains owned by the ThinBox. If you wish to relinquish ownership, use into_raw.

Notes

This method returns a raw mutable pointer, which is dangerous to use. However ThinBox is guaranteed to never store an internal reference to its owned value so dereferencing this pointer does not necessarily cause undefined-behavior.

pub fn leak<'a>(thin: Self) -> &'a mut T

Leaks the contained value in a manner similar to Box::leak.

Unlike Box::leak, if T is unsized it is not valid to pass the returned reference to Box::from_raw or ThinBox::from_raw.

pub unsafe fn transmute_into<U>(thin: Self, dest: *mut U)

Moves the owned value into dest by transmuting into U.

Notes

The value pointed to by dest, if any, is not dropped. The owned value of the ThinBox does not need to be properly aligned as a U.

Safety

Immediate undefined behavior occurs if U is larger in size than the owned value or if dest is not valid for writes. Otherwise any undefined behavior is deferred to later operations which dereference dest and thereby observe the result of the transmutation.

impl<T> ThinBox<T>

pub fn new(value: T) -> Self

Creates a new ThinBox by moving a sized value to the heap.

Notes

Doing this passes up your opportunity to coerce the value to an unsized type, thereby defeating most of the usefulness of ThinBox. You should strongly consider using Box instead if you are not constrained by some other library which consumes instances of ThinBox.

pub fn from_box(boxed: Box<T>) -> Self

Converts a sized Box into a ThinBox. This operation is zero-cost.

pub fn into_box(thin: Self) -> Box<T>

Converts a sized ThinBox into a Box. This operation is zero-cost.

pub fn into_inner(thin: Self) -> T

Moves the owned value out of the sized ThinBox.

Trait Implementations

impl<T: ?Sized> AsMut<T> for ThinBox<T>

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

Performs the conversion.

impl<T: ?Sized> AsRef<T> for ThinBox<T>

fn as_ref(&self) -> &T

Performs the conversion.

impl<T: ?Sized> Borrow<T> for ThinBox<T>

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<T: ?Sized> BorrowMut<T> for ThinBox<T>

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

Mutably borrows from an owned value.

impl<T: Clone> Clone for ThinBox<T>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Debug + ?Sized> Debug for ThinBox<T>

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

Formats the value using the given formatter.

impl<T: ?Sized> Deref for ThinBox<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T: ?Sized> DerefMut for ThinBox<T>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T: Display + ?Sized> Display for ThinBox<T>

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

Formats the value using the given formatter.

impl<T: ?Sized> Drop for ThinBox<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T> From<T> for ThinBox<T>

fn from(value: T) -> Self

Performs the conversion.

impl<T: Hash + ?Sized> Hash for ThinBox<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, 

Feeds a slice of this type into the given [Hasher].

impl<T> Pointer for ThinBox<T>

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

Formats the value using the given formatter.

impl<T: Send + ?Sized> Send for ThinBox<T>

impl<T: Sync + ?Sized> Sync for ThinBox<T>

impl<T: UnwindSafe + ?Sized> UnwindSafe for ThinBox<T>