Struct hato::Hato

pub struct Hato<Trait: ?Sized + Pointee<Metadata = DynMetadata<Trait>>>(/* private fields */);

Arenas of heterogeneous trait objects, stored by type in separate vectors.

As with bump allocators, Drop implementations will not be invoked on deallocation or calls to remove. If you need to run the logic contained in destructors, you can acquire a mutable reference with get_mut, and then call core::ptr::drop_in_place.

This type is subject to the ABA problem. Using handles of previously removed elements will not trigger errors but will return stale or newly inserted elements. This can lead to unexpected behavior, as shown below:

// Initialize the collection
let mut arena = hato::Hato::<dyn core::fmt::Debug>::default();

// Insert an element...
let x = arena.push(5_u8);

// ... then remove it
arena.remove(x);

// ! We can still use the handle to access it
assert_eq!(format!("{:?}", arena.get(x)), "5");

// Insert a new element into the arena
let _y = arena.push(9_u8);

// ! The old handle accesses the repurposed capacity
assert_eq!(format!("{:?}", arena.get(x)), "9");

Implementations

impl<Trait: ?Sized + Pointee<Metadata = DynMetadata<Trait>>> Hato<Trait>

pub fn push<T: Unsize<Trait> + Unscrupulous>(&mut self, x: T) -> Handle

Insert x into the arena for its specific type.

Panics

This function will panic if the number of arenas overflows the index type.

pub unsafe fn get(&self, handle: Handle) -> &Trait

Retrieve the element identified by handle as a trait object.

Safety

The handle must originate from the same instance of Hato.

pub fn get_mut(&mut self, handle: Handle) -> &mut Trait

Retrieve the element identified by handle as a mutable trait object.

Safety

The handle must originate from the same instance of Hato.

pub fn remove(&mut self, handle: Handle)

Remove the element identified by handle from the collection.

Trait Implementations

impl<Trait: ?Sized + Pointee<Metadata = DynMetadata<Trait>>> Clone for Hato<Trait>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<Trait: Debug + ?Sized + Pointee<Metadata = DynMetadata<Trait>>> Debug for Hato<Trait>

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

Formats the value using the given formatter.

impl<Trait: ?Sized + Pointee<Metadata = DynMetadata<Trait>>> Default for Hato<Trait>

fn default() -> Self

Returns the “default value” for a type.