Enum Propagate 

pub enum Propagate {
    None,
    UpdatePseudoElements,
    InheritedOnly,
    RecalcChildren,
    RecalcDescendants,
}

Describes how style changes should propagate to children.

This enum is ordered by “intensity” - higher variants require more work. The ordering enables max() comparisons when combining changes.

Variants

None

No children need style updates.

UpdatePseudoElements

Only update pseudo-elements (like scrollbars). Children can keep their existing computed styles.

InheritedOnly

Only inherited properties changed (font-size, color, etc.). Children can use a fast path that skips full selector resolution and only propagates the changed inherited values.

This is a significant optimization: if a parent’s font-size changes, children using em units need recalc, but we can skip re-matching selectors like :hover, classes, etc.

RecalcChildren

Recalculate style for immediate children. Typically used when a class was applied that children might match.

RecalcDescendants

Recalculate style for all descendants. Used when a deep structural change occurred (e.g., selector that matches nested elements changed).

Implementations

impl Propagate

pub fn requires_child_traversal(&self) -> bool

Returns true if this propagation requires any child traversal.

pub fn requires_full_resolution(&self) -> bool

Returns true if this propagation requires full style resolution. When false, the “inherited only” fast path can be used.

pub fn is_recursive(&self) -> bool

Returns true if all descendants need recalc, not just immediate children.

Trait Implementations

impl Clone for Propagate

fn clone(&self) -> Propagate

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Propagate

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

Formats the value using the given formatter.

impl Default for Propagate

fn default() -> Propagate

Returns the “default value” for a type.

impl Ord for Propagate

fn cmp(&self, other: &Propagate) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Propagate

fn eq(&self, other: &Propagate) -> 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 PartialOrd for Propagate

fn partial_cmp(&self, other: &Propagate) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Propagate

impl Eq for Propagate

impl StructuralPartialEq for Propagate