Struct Arena 

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

A minimal generational arena (house rule: 40 boring lines beat a dependency). Slots are reused; each reuse bumps the generation. Insertion is checked (0056 AR13): a slot whose generation would wrap is retired — never reused — so a stale key can never alias a new occupant, and a full index space refuses instead of truncating slots.len() onto a live slot.

Implementations

impl<K, T> Arena<K, T>

pub fn seed_with<U>(&self, f: impl FnMut(&T) -> U) -> ArenaSeed<U>

Capture the arena, mapping every live value through f.

pub fn from_seed(seed: ArenaSeed<T>) -> Result<Self, ArenaSeedError>

Rebuild an arena. The free list must name only empty slots, each at most once; a seed that disagrees is rejected, never coerced into a plausible-but-wrong identity layout. Empty slots missing from the free list are retired identities, not corruption.

impl<K, T> Arena<K, T>

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

Checked insertion: reuses a free slot only when its generation can advance without wrapping; retired (wrap-risk) slots are dropped from the free list for good. Fails only when no slot is reusable and the index space itself is full — the arena is left unchanged, so an in-flight operation keeps every existing document/edit.

pub fn insert_capacity(&self) -> u64

How many more inserts this arena can serve: reusable free slots plus the remaining index space. Multi-document operations preflight against this instead of failing halfway through.

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

None for a stale id — never the wrong document.

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

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

Remove and return the value; stale ids get None.

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

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

Mutable values without copying keys or exposing vacant slots.

pub fn len(&self) -> usize

pub fn clear(&mut self)

Drop every live value (slot reuse still bumps generations).

pub fn is_empty(&self) -> bool

Trait Implementations

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

fn default() -> Self

Returns the “default value” for a type.