layout: Simplify and generalize the usage of pseudo-elements (#36202)

- Remove the last remaining Servo-specific PseudoElement enum from
  layout. This was made to select `::before` and `::after` (both eager
  pseudo-elements), but now `traverse_pseudo_element` is called
  `traverse_eager_pseudo_element` and should work on any eager pseudo
  element.
- Expose a single way of getting psuedo-element variants of
  ThreadSafeLayoutElement in the Layout DOM, which returns `None` when
  the pseudo-element doesn't apply (not defined for eager
  pseudo-elements or when trying to get `<details>` related
  pseudo-elements on elements that they don't apply to).
- Ensure that NodeAndStyleInfo always refers to a node. This is done by
  making sure that anonymous boxes are all associated with their
  originating node.

These changes are prepatory work for implementation of the `::marker`
pseudo-element as well as ensuring that all anonymous boxes can be
cached into the box tree eventually.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>
This commit is contained in:
Martin Robinson 2025-03-29 13:41:04 +01:00 committed by GitHub
parent c30ad5a30e
commit b5c8164e99
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15 changed files with 278 additions and 354 deletions

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@ -436,8 +436,8 @@ impl<'dom> ServoThreadSafeLayoutNodeChildrenIterator<'dom> {
pub fn new(parent: ServoThreadSafeLayoutNode<'dom>) -> Self {
let first_child = match parent.pseudo_element() {
None => parent
.get_pseudo(PseudoElement::Before)
.or_else(|| parent.get_details_summary_pseudo())
.with_pseudo(PseudoElement::Before)
.or_else(|| parent.with_pseudo(PseudoElement::DetailsSummary))
.or_else(|| unsafe { parent.dangerous_first_child() }),
Some(PseudoElement::DetailsContent) | Some(PseudoElement::DetailsSummary) => unsafe {
parent.dangerous_first_child()
@ -503,18 +503,18 @@ impl<'dom> Iterator for ServoThreadSafeLayoutNodeChildrenIterator<'dom> {
self.current_node = match node.pseudo_element() {
Some(PseudoElement::Before) => self
.parent_node
.get_details_summary_pseudo()
.with_pseudo(PseudoElement::DetailsSummary)
.or_else(|| unsafe { self.parent_node.dangerous_first_child() })
.or_else(|| self.parent_node.get_pseudo(PseudoElement::After)),
.or_else(|| self.parent_node.with_pseudo(PseudoElement::After)),
Some(PseudoElement::DetailsSummary) => {
self.parent_node.get_details_content_pseudo()
self.parent_node.with_pseudo(PseudoElement::DetailsContent)
},
Some(PseudoElement::DetailsContent) => {
self.parent_node.get_pseudo(PseudoElement::After)
self.parent_node.with_pseudo(PseudoElement::After)
},
Some(PseudoElement::After) => None,
None | Some(_) => unsafe { node.dangerous_next_sibling() }
.or_else(|| self.parent_node.get_pseudo(PseudoElement::After)),
.or_else(|| self.parent_node.with_pseudo(PseudoElement::After)),
};
}
node