Struct NodeCache 

pub struct NodeCache {
    pub measure_entries: [Option<SizingCacheEntry>; 9],
    pub layout_entry: Option<LayoutCacheEntry>,
    pub is_empty: bool,
}

Per-node cache entry with 9 measurement slots + 1 full layout slot.

Inspired by Taffy’s Cache struct (9+1 slots per node). The deterministic slot index is computed from the constraint combination, so entries never clobber each other (unlike the old global BTreeMap where fixed-point collisions were possible).

NOT stored on LayoutNode — lives in the external LayoutCacheMap.

Fields

measure_entries: [Option<SizingCacheEntry>; 9]

9 measurement slots (Taffy’s deterministic scheme):

• Slot 0: both dimensions known
• Slots 1-2: only width known (MaxContent/Definite vs MinContent)
• Slots 3-4: only height known (MaxContent/Definite vs MinContent)
• Slots 5-8: neither known (2×2 combos of width/height constraint types)

layout_entry: Option<LayoutCacheEntry>

1 full layout slot (with child positions, overflow, baseline). Only populated after PerformLayout, not after ComputeSize.

is_empty: bool

Fast check for dirty propagation (Taffy optimization). When true, all slots are empty — ancestors are also dirty.

Implementations

impl NodeCache

pub fn clear(&mut self)

Clear all cache entries, marking this node as dirty.

pub fn slot_index( width_known: bool, height_known: bool, width_type: AvailableWidthType, height_type: AvailableWidthType, ) -> usize

Compute the deterministic slot index from constraint dimensions.

This is Taffy’s slot selection scheme: given whether width/height are “known” (definite constraint provided by parent) and what type of constraint applies to the unknown dimension(s), we get a unique slot 0–8.

pub fn get_size( &self, slot: usize, known_dims: LogicalSize, ) -> Option<&SizingCacheEntry>

Look up a sizing cache entry, implementing Taffy’s “result matches request” optimization: if the caller provides the result size as a known dimension (common in Pass1→Pass2 transitions), it’s still a cache hit.

pub fn store_size(&mut self, slot: usize, entry: SizingCacheEntry)

Store a sizing result in the given slot.

pub fn get_layout(&self, known_dims: LogicalSize) -> Option<&LayoutCacheEntry>

Look up the full layout cache entry.

pub fn store_layout(&mut self, entry: LayoutCacheEntry)

Store a full layout result.

Trait Implementations

impl Clone for NodeCache

fn clone(&self) -> NodeCache

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for NodeCache

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

Formats the value using the given formatter.

impl Default for NodeCache

fn default() -> Self

Returns the “default value” for a type.