Struct fixed_typed_arena::ManuallyDropArena

pub struct ManuallyDropArena<T, const CHUNK_SIZE: usize>(_);

Like Arena, but returns references of any lifetime, including 'static.

This lets the arena be used without being borrowed, but it comes with the tradeoff that the arena leaks memory unless the unsafe drop method is called.

Implementations

impl<T, const CHUNK_SIZE: usize> ManuallyDropArena<T, CHUNK_SIZE>

pub fn new() -> Self

Creates a new ManuallyDropArena.

pub fn alloc<'a>(&mut self, value: T) -> &'a mut T

Allocates a new item in the arena and initializes it with value. Returns a reference to the allocated item. The reference can have any lifetime, including 'static, as long as T outlives that lifetime.

pub unsafe fn drop(&mut self)

Drops the contents of the arena. The arena will leak memory when dropped unless this method is called.

Safety

You must ensure that no references to items (or parts of items) in the arena exist when calling this method, except possibly for references within the items themselves.

However, if there are references to other items (or parts of items) within the items themselves, at least one of the following must be true:

• T does not have a custom Drop impl.
• T’s Drop impl does not directly or indirectly access any data via the references to other items or parts of items. (This is essentially the requirement imposed by #[may_dangle].)

pub unsafe fn manually_drop(&mut self)

Alias of Self::drop. Can be used to prevent name collisions when this arena is stored in a Deref type:

let mut arena = Box::new(ManuallyDropArena::<u8, 8>::new());
//unsafe { arena.drop() }; // Compile error: resolves to `Drop::drop`
unsafe { arena.manually_drop() }; // Works as expected

Safety

Same requirements as Self::drop.

Trait Implementations

impl<T, const CHUNK_SIZE: usize> Default for ManuallyDropArena<T, CHUNK_SIZE>

fn default() -> Self

Returns the “default value” for a type.