Struct NodePool 

pub struct NodePool { /* private fields */ }

A reusable pool of A11yNode allocations, keyed by NodeId.

Reduces per-frame heap allocations when the accessibility tree is rebuilt on every frame: rather than dropping and re-allocating every node, the pool keeps previously-allocated structs (and their internal Vec allocations) on a free list.

Invariants

• A node is either active (in active) or free (in free_list), never both simultaneously.
• After recycle, active is empty and free_list holds all previously-active nodes.
• After clear, both maps are empty.

Implementations

impl NodePool

pub fn new() -> Self

Create a new, empty pool.

pub fn alloc(&mut self, id: NodeId, node: A11yNode)

Place node into the active map under id.

If a node with the same id already exists it is silently replaced and the old node is dropped (not returned to the free list, to avoid a same-id duplicate).

pub fn alloc_recycled( &mut self, id: NodeId, role: WidgetRole, label: Option<String>, ) -> &mut A11yNode

Allocate a node slot, optionally reusing memory from the free list.

If a free node is available its struct is taken from the free list and reset to the supplied id, role, and label before being placed in the active map. Otherwise a fresh node is created.

This is the preferred allocation path for hot paths that care about minimising heap allocation churn.

pub fn get(&self, id: &NodeId) -> Option<&A11yNode>

Retrieve an active node by its NodeId.

pub fn get_mut(&mut self, id: &NodeId) -> Option<&mut A11yNode>

Retrieve a mutable reference to an active node.

pub fn recycle(&mut self)

Move all active nodes back to the free list for reuse next frame.

After this call active_count() == 0 and free_count() reflects the total number of recycled nodes.

pub fn active_count(&self) -> usize

Number of currently-active nodes.

pub fn free_count(&self) -> usize

Number of nodes available for reuse.

pub fn clear(&mut self)

Discard all nodes (active and free).

pub fn iter_active(&self) -> impl Iterator<Item = (&NodeId, &A11yNode)>

Iterate over all active nodes.

Trait Implementations

impl Debug for NodePool

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

Formats the value using the given formatter.

impl Default for NodePool

fn default() -> NodePool

Returns the “default value” for a type.