Struct Arena 

pub struct Arena<K: ArenaKey, T> { /* private fields */ }

A slot map: dense Vec storage with O(1) insert/remove/lookup by key.

Implementations

impl<K: ArenaKey, T> Arena<K, T>

pub fn new() -> Self

An empty arena.

pub fn len(&self) -> usize

Number of live entries.

pub fn is_empty(&self) -> bool

Whether there are no live entries.

pub fn capacity(&self) -> usize

Number of allocated slots, including tombstones.

pub fn insert(&mut self, value: T) -> K

Insert value, returning its freshly allocated key.

pub fn insert_with(&mut self, make: impl FnOnce(K) -> T) -> K

Insert a value that needs to know its own key (e.g. a node that stores its own NodeId).

pub fn contains(&self, key: K) -> bool

Whether key refers to a live entry.

pub fn get(&self, key: K) -> Option<&T>

Borrow the entry for key, if live.

pub fn get_mut(&mut self, key: K) -> Option<&mut T>

Mutably borrow the entry for key, if live.

pub fn remove(&mut self, key: K) -> Option<T>

Remove and return the entry for key, recycling the slot.

pub fn iter(&self) -> impl Iterator<Item = (K, &T)>

Iterate over (key, &value) for all live entries, in ascending key order.

pub fn keys(&self) -> impl Iterator<Item = K> + '_

Iterate over the keys of all live entries.

pub fn values(&self) -> impl Iterator<Item = &T>

Iterate over &value for all live entries.

pub fn values_mut(&mut self) -> impl Iterator<Item = &mut T>

Iterate over &mut value for all live entries.

Trait Implementations

impl<K: Clone + ArenaKey, T: Clone> Clone for Arena<K, T>

fn clone(&self) -> Arena<K, T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<K: Debug + ArenaKey, T: Debug> Debug for Arena<K, T>

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

Formats the value using the given formatter.

impl<K: ArenaKey, T> Default for Arena<K, T>

fn default() -> Self

Returns the “default value” for a type.