Struct taffy::tree::cache::Cache

pub struct Cache {
    final_layout_entry: Option<CacheEntry<LayoutOutput>>,
    measure_entries: [Option<CacheEntry<Size<f32>>>; 9],
}

A cache for caching the results of a sizing a Grid Item or Flexbox Item

Fields

final_layout_entry: Option<CacheEntry<LayoutOutput>>

The cache entry for the node’s final layout

measure_entries: [Option<CacheEntry<Size<f32>>>; 9]

The cache entries for the node’s preliminary size measurements

Implementations

impl Cache

pub const fn new() -> Self

Create a new empty cache

fn compute_cache_slot( known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>, ) -> usize

Return the cache slot to cache the current computed result in

Caching Strategy

We need multiple cache slots, because a node’s size is often queried by it’s parent multiple times in the course of the layout process, and we don’t want later results to clobber earlier ones.

The two variables that we care about when determining cache slot are:

• How many “known_dimensions” are set. In the worst case, a node may be called first with neither dimension known, then with one dimension known (either width of height - which doesn’t matter for our purposes here), and then with both dimensions known.
• Whether unknown dimensions are being sized under a min-content or a max-content available space constraint (definite available space shares a cache slot with max-content because a node will generally be sized under one or the other but not both).

Cache slots:

• Slot 0: Both known_dimensions were set
• Slots 1-4: 1 of 2 known_dimensions were set and:
  • Slot 1: width but not height known_dimension was set and the other dimension was either a MaxContent or Definite available space constraintraint
  • Slot 2: width but not height known_dimension was set and the other dimension was a MinContent constraint
  • Slot 3: height but not width known_dimension was set and the other dimension was either a MaxContent or Definite available space constraintable space constraint
  • Slot 4: height but not width known_dimension was set and the other dimension was a MinContent constraint
• Slots 5-8: Neither known_dimensions were set and:
  • Slot 5: x-axis available space is MaxContent or Definite and y-axis available space is MaxContent or Definite
  • Slot 6: x-axis available space is MaxContent or Definite and y-axis available space is MinContent
  • Slot 7: x-axis available space is MinContent and y-axis available space is MaxContent or Definite
  • Slot 8: x-axis available space is MinContent and y-axis available space is MinContent

pub fn get( &self, known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>, run_mode: RunMode, ) -> Option<LayoutOutput>

Try to retrieve a cached result from the cache

pub fn store( &mut self, known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>, run_mode: RunMode, layout_output: LayoutOutput, )

Store a computed size in the cache

pub fn clear(&mut self)

Clear all cache entries

pub fn is_empty(&self) -> bool

Returns true if all cache entries are None, else false

Trait Implementations

impl Clone for Cache

fn clone(&self) -> Cache

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Cache

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

Formats the value using the given formatter.

impl Default for Cache

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for Cache

fn eq(&self, other: &Cache) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Cache

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Cache