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style: Implement parsing / selector-matching for :is() and :where().

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This implements the easy / straight-forward parts of the :where / :is
selectors.

The biggest missing piece is to handle properly invalidation when there
are combinators present inside the :where. That's the hard part of this,
actually.

But this is probably worth landing in the interim. This fixes some of
the visitors that were easy to fix.

Differential Revision: https://phabricator.services.mozilla.com/D70788
This commit is contained in:
Emilio Cobos Álvarez 2020-04-17 13:37:59 +00:00
parent 66f14773c6
commit 83ea321096
10 changed files with 338 additions and 223 deletions
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45
components/style/stylist.rs
View file

@ -42,8 +42,7 @@ use selectors::attr::{CaseSensitivity, NamespaceConstraint};
use selectors::bloom::BloomFilter;
use selectors::matching::VisitedHandlingMode;
use selectors::matching::{matches_selector, ElementSelectorFlags, MatchingContext, MatchingMode};
use selectors::parser::{AncestorHashes, Combinator, Component, Selector};
use selectors::parser::{SelectorIter, Visit};
use selectors::parser::{AncestorHashes, Combinator, Component, Selector, SelectorIter};
use selectors::visitor::SelectorVisitor;
use selectors::NthIndexCache;
use servo_arc::{Arc, ArcBorrow};
@ -1530,11 +1529,11 @@ impl SelectorMapEntry for RevalidationSelectorAndHashes {
/// A selector visitor implementation that collects all the state the Stylist
/// cares about a selector.
struct StylistSelectorVisitor<'a> {
/// Whether the selector needs revalidation for the style sharing cache.
needs_revalidation: bool,
/// Whether we've past the rightmost compound selector, not counting
/// pseudo-elements.
passed_rightmost_selector: bool,
/// Whether the selector needs revalidation for the style sharing cache.
needs_revalidation: &'a mut bool,
/// The filter with all the id's getting referenced from rightmost
/// selectors.
mapped_ids: &'a mut PrecomputedHashSet<Atom>,
@ -1582,14 +1581,10 @@ impl<'a> SelectorVisitor for StylistSelectorVisitor<'a> {
type Impl = SelectorImpl;
fn visit_complex_selector(&mut self, combinator: Option<Combinator>) -> bool {
self.needs_revalidation =
self.needs_revalidation || combinator.map_or(false, |c| c.is_sibling());
*self.needs_revalidation =
*self.needs_revalidation || combinator.map_or(false, |c| c.is_sibling());
// NOTE(emilio): This works properly right now because we can't store
// complex selectors in nested selectors, otherwise we may need to
// rethink this.
//
// Also, note that this call happens before we visit any of the simple
// NOTE(emilio): this call happens before we visit any of the simple
// selectors in the next ComplexSelector, so we can use this to skip
// looking at them.
self.passed_rightmost_selector = self.passed_rightmost_selector ||
@ -1598,6 +1593,22 @@ impl<'a> SelectorVisitor for StylistSelectorVisitor<'a> {
true
}
fn visit_selector_list(&mut self, list: &[Selector<Self::Impl>]) -> bool {
for selector in list {
let mut nested = StylistSelectorVisitor {
passed_rightmost_selector: false,
needs_revalidation: &mut *self.needs_revalidation,
attribute_dependencies: &mut *self.attribute_dependencies,
state_dependencies: &mut *self.state_dependencies,
document_state_dependencies: &mut *self.document_state_dependencies,
mapped_ids: &mut *self.mapped_ids,
};
let _ret = selector.visit(&mut nested);
debug_assert!(_ret, "We never return false");
}
true
}
fn visit_attribute_selector(
&mut self,
_ns: &NamespaceConstraint<&Namespace>,
@ -1610,7 +1621,7 @@ impl<'a> SelectorVisitor for StylistSelectorVisitor<'a> {
}
fn visit_simple_selector(&mut self, s: &Component<SelectorImpl>) -> bool {
self.needs_revalidation = self.needs_revalidation ||
*self.needs_revalidation = *self.needs_revalidation ||
component_needs_revalidation(s, self.passed_rightmost_selector);
match *s {
@ -2022,8 +2033,9 @@ impl CascadeData {
if rebuild_kind.should_rebuild_invalidation() {
self.invalidation_map.note_selector(selector, quirks_mode)?;
let mut needs_revalidation = false;
let mut visitor = StylistSelectorVisitor {
needs_revalidation: false,
needs_revalidation: &mut needs_revalidation,
passed_rightmost_selector: false,
attribute_dependencies: &mut self.attribute_dependencies,
state_dependencies: &mut self.state_dependencies,
@ -2033,7 +2045,7 @@ impl CascadeData {
rule.selector.visit(&mut visitor);
if visitor.needs_revalidation {
if needs_revalidation {
self.selectors_for_cache_revalidation.insert(
RevalidationSelectorAndHashes::new(
rule.selector.clone(),
@ -2365,14 +2377,15 @@ pub fn needs_revalidation_for_testing(s: &Selector<SelectorImpl>) -> bool {
let mut mapped_ids = Default::default();
let mut state_dependencies = ElementState::empty();
let mut document_state_dependencies = DocumentState::empty();
let mut needs_revalidation = false;
let mut visitor = StylistSelectorVisitor {
needs_revalidation: false,
passed_rightmost_selector: false,
needs_revalidation: &mut needs_revalidation,
attribute_dependencies: &mut attribute_dependencies,
state_dependencies: &mut state_dependencies,
document_state_dependencies: &mut document_state_dependencies,
mapped_ids: &mut mapped_ids,
};
s.visit(&mut visitor);
visitor.needs_revalidation
needs_revalidation
}