Struct Box

pub struct Box<T: ?Sized, S: Storage = Global> { /* private fields */ }

A type that owns a single T allocated in a Storage

This currently stores an extra dangling non-null pointer when using the nightly feature, so that CoerceUnsized can attach metadata to it when this Box get unsized

Box does not support T: ?Sized types when not using the nightly feature

Implementations

impl<T, S: Storage + Default> Box<T, S>

pub fn new(value: T) -> Result<Self, StorageAllocError>

Box::new_in but using Default::default for the Storage

pub fn new_with(f: impl FnOnce() -> T) -> Result<Self, StorageAllocError>

Box::new_with_in but using Default::default for the Storage

This function has an advantage over Box::new for large objects where because the allocation is done before f is called, the stack space for the return value of f may be elided by the compiler

impl<T, S: Storage> Box<T, S>

pub fn new_in(value: T, storage: S) -> Result<Self, StorageAllocError>

Allocates room for a T in storage and moves value into it

pub fn new_with_in( f: impl FnOnce() -> T, storage: S, ) -> Result<Self, StorageAllocError>

Allocates room for a T in storage and constructs value into it

This function has an advantage over Box::new_in for large objects where because the allocation is done before f is called, the stack space for the return value of f may be elided by the compiler

pub fn into_inner(self) -> T

Moves the T out of this Box

impl<T: ?Sized, S: Storage> Box<T, S>

pub unsafe fn from_raw_parts( storage: S, handle: S::Handle, metadata: <T as Pointee>::Metadata, ) -> Self

Reconstructs a Box from a Storage, Storage::Handle, and Pointee::Metadata

The opposite of Box::into_raw_parts

Safety

• handle must represent a valid allocation in storage of size_of::<T>() bytes
• metadata must be a valid pointer metadata for the T that handle represents

pub fn into_raw_parts(b: Self) -> (S, S::Handle, <T as Pointee>::Metadata)

Splits the Box into its Storage, Storage::Handle, and Pointee::Metadata

The opposite of Box::from_raw_parts

pub fn as_ptr(&self) -> NonNull<T>

Gets a NonNull<T> to the T stored in this Box

impl<S: Storage> Box<dyn Any, S>

pub fn downcast<T: 'static>(b: Self) -> Result<Box<T, S>, Self>

Available on crate feature nightly only.

Attempts to downcast the dyn Any to a T

pub unsafe fn downcast_unchecked<T: 'static>(b: Self) -> Box<T, S>

Available on crate feature nightly only.

Downcasts the dyn Any to a T, without any checks

The safe version of this function is Box::downcast

Safety

The contained value must be of type T

Trait Implementations

impl<T: ?Sized, S: Storage> Deref for Box<T, S>

type Target = T

The resulting type after dereferencing.

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

Dereferences the value.

impl<T: ?Sized, S: Storage> DerefMut for Box<T, S>

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

Mutably dereferences the value.

impl<T: ?Sized, S: Storage> Drop for Box<T, S>

fn drop(&mut self)

Executes the destructor for this type.

impl<T, U, S> CoerceUnsized<Box<U, S>> for Box<T, S>

where T: Unsize<U> + ?Sized, U: ?Sized, S: Storage,

Available on crate feature nightly only.

impl<T, S> Send for Box<T, S>

where T: Send + ?Sized, S: Send + Storage, S::Handle: Send,

impl<T, S> Sync for Box<T, S>

where T: Sync + ?Sized, S: Sync + Storage, S::Handle: Sync,