Struct ShapeTransitionTable 

pub struct ShapeTransitionTable { /* private fields */ }

Manages shape creation and transitions.

Thread-safety: This is NOT thread-safe. For multi-threaded use, wrap in a Mutex or use thread-local instances.

Implementations

impl ShapeTransitionTable

pub fn new() -> Self

Create a new transition table with a root shape (id=0, no properties).

pub fn root() -> ShapeId

Returns the root shape ID (always ShapeId(0)).

pub fn get_shape(&self, id: ShapeId) -> &Shape

Get a shape by its ID. Panics if the ID is invalid.

pub fn try_get_shape(&self, id: ShapeId) -> Option<&Shape>

Get a shape by its ID, returning None if the ID is not present in this table.

Use this when a ShapeId may have originated from a different transition table (for example, a HashMapData::shape_id computed under the process-default ambient handle but observed inside a per-VM scope). In that case callers should degrade to the hash-based slow path rather than panic on an out-of-range index.

pub fn transition(&mut self, from: ShapeId, property_name: u32) -> ShapeId

Transition from from shape by adding property_name.

Returns the existing child shape if the transition already exists, otherwise creates a new shape with the property appended.

pub fn shape_for_keys(&mut self, keys: &[u32]) -> ShapeId

Build a shape by transitioning from root through all keys in order.

pub fn property_index( &self, shape_id: ShapeId, property_name: u32, ) -> Option<usize>

Find the slot index of property_name in the given shape.

Returns None if the property is not part of this shape, or if shape_id does not belong to this table (e.g. a stale ID carried over from a different ambient handle — see try_get_shape). O(n) scan of the shape’s properties list.

pub fn shape_count(&self) -> usize

Total number of shapes in the table.