Struct Slab

pub struct Slab<T> { /* private fields */ }

A simple, uni-typed slab arena.

Implementations

impl<T> Slab<T>

pub const MAX_CAPACITY: usize = 4_294_967_294usize

The maximum capacity any Slab can have: u32::MAX - 1.

pub fn new() -> Self

Construct a new, empty slab.

pub fn with_capacity(capacity: usize) -> Self

Construct a new, empty slab, pre-reserving space for at least capacity elements.

pub fn reserve(&mut self, additional: usize)

Ensure that there is space for at least additional elements in this slab.

Panics

Panics if the new capacity exceeds Self::MAX_CAPACITY.

pub fn capacity(&self) -> usize

What is the capacity of this slab? That is, how many entries can it contain within its current underlying storage?

pub fn len(&self) -> usize

How many values are currently allocated within this slab?

pub fn is_empty(&self) -> bool

Are there zero allocated values within this slab?

pub fn try_alloc(&mut self, value: T) -> Result<Id, T>

Try to allocate a T value within this slab.

If there is no available capacity, ownership of the given value is returned via Err(value).

pub fn alloc(&mut self, value: T) -> Id

Allocate a T value within this slab, allocating additional underlying storage if there is no available capacity.

Panics

Panics if allocating this value requires reallocating the underlying storage, and the new capacity exceeds Slab::MAX_CAPACITY.

pub fn next_id(&self) -> Id

Get the Id that will be returned for the next allocation in this slab.

pub fn get(&self, id: Id) -> Option<&T>

Get a shared borrow of the value associated with id.

Returns None if the value has since been deallocated.

If id comes from a different Slab instance, this method may panic, return None, or return an arbitrary value.

pub fn get_mut(&mut self, id: Id) -> Option<&mut T>

Get an exclusive borrow of the value associated with id.

Returns None if the value has since been deallocated.

If id comes from a different Slab instance, this method may panic, return None, or return an arbitrary value.

pub fn contains(&self, id: Id) -> bool

Does this slab contain an allocated value for id?

pub fn dealloc(&mut self, id: Id) -> T

Deallocate the value associated with the given id.

If id comes from a different Slab instance, this method may panic or deallocate an arbitrary value.

pub fn iter(&self) -> impl Iterator<Item = (Id, &T)> + '_

Iterate over all values currently allocated within this Slab.

Yields pairs of an Id and the Id’s associated value.

Iteration order is undefined.

pub fn iter_mut(&mut self) -> impl Iterator<Item = (Id, &mut T)> + '_

Mutably iterate over all values currently allocated within this Slab.

Yields pairs of an Id and the Id’s associated value.

Iteration order is undefined.

pub fn drain(&mut self) -> impl Iterator<Item = (Id, T)> + '_

Iterate over and remove all entries in this slab.

The slab will be empty after calling this method.

Yields pairs of an Id and the Id’s associated value.

Iteration order is undefined.

Trait Implementations

impl<T> Debug for Slab<T>

where T: Debug,

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

Formats the value using the given formatter.

impl<T> Default for Slab<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T> Index<Id> for Slab<T>

type Output = T

The returned type after indexing.

fn index(&self, id: Id) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<T> IndexMut<Id> for Slab<T>

fn index_mut(&mut self, id: Id) -> &mut Self::Output

Performs the mutable indexing (container[index]) operation.