style/invalidation/element/
relative_selector.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5//! Invalidation of element styles relative selectors.
6
7use crate::data::ElementData;
8use crate::dom::{TElement, TNode};
9#[cfg(feature = "gecko")]
10use crate::gecko_bindings::structs::ServoElementSnapshotTable;
11use crate::invalidation::element::element_wrapper::ElementWrapper;
12use crate::invalidation::element::invalidation_map::{
13    AdditionalRelativeSelectorInvalidationMap, Dependency, DependencyInvalidationKind,
14    InvalidationMap, NormalDependencyInvalidationKind, RelativeDependencyInvalidationKind,
15    TSStateForInvalidation,
16};
17use crate::invalidation::element::invalidator::{
18    DescendantInvalidationLists, Invalidation, InvalidationProcessor, InvalidationResult,
19    InvalidationVector, SiblingTraversalMap, TreeStyleInvalidator,
20};
21use crate::invalidation::element::restyle_hints::RestyleHint;
22use crate::invalidation::element::state_and_attributes::{
23    check_dependency, dependency_may_be_relevant, invalidated_descendants, invalidated_self,
24    invalidated_sibling, push_invalidation, should_process_descendants,
25};
26#[cfg(feature = "servo")]
27use crate::selector_parser::SnapshotMap as ServoElementSnapshotTable;
28use crate::stylist::{CascadeData, Stylist};
29use dom::ElementState;
30use fxhash::FxHashMap;
31use selectors::matching::{
32    matches_selector, ElementSelectorFlags, IncludeStartingStyle, MatchingContext,
33    MatchingForInvalidation, MatchingMode, NeedsSelectorFlags, QuirksMode, SelectorCaches,
34    VisitedHandlingMode,
35};
36use selectors::parser::SelectorKey;
37use selectors::OpaqueElement;
38use smallvec::SmallVec;
39use std::ops::DerefMut;
40
41/// Kind of DOM mutation this relative selector invalidation is being carried out in.
42#[derive(Clone, Copy)]
43pub enum DomMutationOperation {
44    /// Insertion operation, can cause side effect, but presumed already happened.
45    Insert,
46    /// Append operation, cannot cause side effect.
47    Append,
48    /// Removal operation, can cause side effect, but presumed already happened. Sibling relationships are destroyed.
49    Remove,
50    /// Invalidating for side effect of a DOM operation, for the previous sibling.
51    SideEffectPrevSibling,
52    /// Invalidating for side effect of a DOM operation, for the next sibling.
53    SideEffectNextSibling,
54}
55
56impl DomMutationOperation {
57    fn accept<E: TElement>(&self, d: &Dependency, e: E) -> bool {
58        match self {
59            Self::Insert | Self::Append | Self::Remove => {
60                !e.relative_selector_search_direction().is_empty()
61            },
62            // `:has(+ .a + .b)` with `.anchor + .a + .remove + .b` - `.a` would be present
63            // in the search path.
64            Self::SideEffectPrevSibling => {
65                !e.relative_selector_search_direction().is_empty()
66                    && d.right_combinator_is_next_sibling()
67            },
68            // If an element is being removed and would cause next-sibling match to happen,
69            // e.g. `:has(+ .a)` with `.anchor + .remove + .a`, `.a` isn't yet searched
70            // for relative selector matching.
71            Self::SideEffectNextSibling => d.dependency_is_relative_with_single_next_sibling(),
72        }
73    }
74
75    fn is_side_effect(&self) -> bool {
76        match self {
77            Self::Insert | Self::Append | Self::Remove => false,
78            Self::SideEffectPrevSibling | Self::SideEffectNextSibling => true,
79        }
80    }
81}
82
83/// Context required to try and optimize away relative dependencies.
84struct OptimizationContext<'a, E: TElement> {
85    sibling_traversal_map: &'a SiblingTraversalMap<E>,
86    quirks_mode: QuirksMode,
87    operation: DomMutationOperation,
88}
89
90impl<'a, E: TElement> OptimizationContext<'a, E> {
91    fn can_be_ignored(
92        &self,
93        is_subtree: bool,
94        element: E,
95        host: Option<OpaqueElement>,
96        dependency: &Dependency,
97        leftmost_collapse_offset: usize,
98    ) -> bool {
99        if is_subtree {
100            // Subtree elements don't have unaffected sibling to look at.
101            return false;
102        }
103        debug_assert!(
104            matches!(
105                dependency.invalidation_kind(),
106                DependencyInvalidationKind::Relative(..)
107            ),
108            "Non-relative selector being evaluated for optimization"
109        );
110        // This optimization predecates on the fact that there may be a sibling that can readily
111        // "take over" this element.
112        let sibling = match self.sibling_traversal_map.prev_sibling_for(&element) {
113            None => {
114                if matches!(self.operation, DomMutationOperation::Append) {
115                    return false;
116                }
117                match self.sibling_traversal_map.next_sibling_for(&element) {
118                    Some(s) => s,
119                    None => return false,
120                }
121            },
122            Some(s) => s,
123        };
124        {
125            // Run through the affected compund.
126            let mut iter = dependency.selector.iter_from(dependency.selector_offset);
127            while let Some(c) = iter.next() {
128                if c.has_indexed_selector_in_subject() {
129                    // We do not calculate indices during invalidation as they're wasteful - as a side effect,
130                    // such selectors always return true, breaking this optimization. Note that we only check
131                    // this compound only because the check to skip compares against this element's sibling.
132                    // i.e. Given `:has(:nth-child(2) .foo)`, we'd try to find `.foo`'s sibling, which
133                    // shares `:nth-child` up the selector.
134                    return false;
135                }
136            }
137        }
138        let dependency_is_rightmost = dependency.selector_offset == 0;
139        if !dependency_is_rightmost {
140            let combinator = dependency
141                .selector
142                .combinator_at_match_order(dependency.selector_offset - 1);
143            if combinator.is_ancestor() {
144                // We can safely ignore these, since we're about to traverse the
145                // rest of the affected tree anyway to find the rightmost invalidated element.
146                return true;
147            }
148            if combinator.is_sibling() && matches!(self.operation, DomMutationOperation::Append) {
149                // If we're at the top of the DOM tree being mutated, we can ignore it if the
150                // operation is append - we know we'll cover all the later siblings and their descendants.
151                return true;
152            }
153        }
154
155        // We have a situation like `:has(.item .item + .item + .item)`, where the first element in the sibling
156        // chain position (i.e. The element matched by the second `.item` from the left) mutates. By the time we
157        // get here, we've collapsed the 4 dependencies for each of `.item` position into one at the rightmost
158        // position. Before we look for a standin, we need to find which `.item` this element matches - Doing
159        // that would generate more work than it saves.
160        if dependency_is_rightmost
161            && leftmost_collapse_offset != dependency.selector_offset
162            && self
163                .sibling_traversal_map
164                .next_sibling_for(&element)
165                .is_some()
166        {
167            return false;
168        }
169
170        let mut caches = SelectorCaches::default();
171        let mut matching_context = MatchingContext::new(
172            MatchingMode::Normal,
173            None,
174            &mut caches,
175            self.quirks_mode,
176            NeedsSelectorFlags::No,
177            MatchingForInvalidation::Yes,
178        );
179        matching_context.current_host = host;
180        let sibling_matches = matches_selector(
181            &dependency.selector,
182            dependency.selector_offset,
183            None,
184            &sibling,
185            &mut matching_context,
186        );
187        if sibling_matches {
188            // Remember that at this point, we know that the combinator to the right of this
189            // compound is a sibling combinator. Effectively, we've found a standin for the
190            // element we're mutating.
191            // e.g. Given `:has(... .a ~ .b ...)`, we're the mutating element matching `... .a`,
192            // if we find a sibling that matches the `... .a`, it can stand in for us.
193            debug_assert!(
194                dependency.next.is_some(),
195                "No relative selector outer dependency?"
196            );
197            return dependency.next.as_ref().map_or(false, |deps| {
198                // ... However, if the standin sibling can be the anchor, we can't skip it, since
199                // that sibling should be invlidated to become the anchor.
200                let next = &deps.as_ref().slice()[0];
201                !matches_selector(
202                    &next.selector,
203                    next.selector_offset,
204                    None,
205                    &sibling,
206                    &mut matching_context,
207                )
208            });
209        }
210        // Ok, there's no standin element - but would this element have matched the upstream
211        // selector anyway? If we don't, either the match exists somewhere far from us
212        // (In which case our mutation doesn't really matter), or it doesn't exist at all,
213        // so we can just skip the invalidation.
214        let (combinator, prev_offset) = {
215            let mut iter = dependency.selector.iter_from(dependency.selector_offset);
216            let mut o = dependency.selector_offset;
217            while iter.next().is_some() {
218                o += 1;
219            }
220            let combinator = iter.next_sequence();
221            o += 1;
222            debug_assert!(
223                combinator.is_some(),
224                "Should at least see a relative combinator"
225            );
226            (combinator.unwrap(), o)
227        };
228        if combinator.is_sibling() && prev_offset >= dependency.selector.len() - 1 {
229            // Hit the relative combinator - we don't have enough information to
230            // see if there's going to be a downstream match.
231            return false;
232        }
233        !matches_selector(
234            &dependency.selector,
235            dependency.selector_offset,
236            None,
237            &element,
238            &mut matching_context,
239        )
240    }
241}
242
243/// Overall invalidator for handling relative selector invalidations.
244pub struct RelativeSelectorInvalidator<'a, 'b, E>
245where
246    E: TElement + 'a,
247{
248    /// Element triggering the invalidation.
249    pub element: E,
250    /// Quirks mode of the current invalidation.
251    pub quirks_mode: QuirksMode,
252    /// Snapshot containing changes to invalidate against.
253    /// Can be None if it's a DOM mutation.
254    pub snapshot_table: Option<&'b ServoElementSnapshotTable>,
255    /// Callback to trigger when the subject element is invalidated.
256    pub invalidated: fn(E, &InvalidationResult),
257    /// The traversal map that should be used to process invalidations.
258    pub sibling_traversal_map: SiblingTraversalMap<E>,
259    /// Marker for 'a lifetime.
260    pub _marker: ::std::marker::PhantomData<&'a ()>,
261}
262
263struct RelativeSelectorInvalidation<'a> {
264    host: Option<OpaqueElement>,
265    kind: RelativeDependencyInvalidationKind,
266    dependency: &'a Dependency,
267}
268
269type ElementDependencies<'a> = SmallVec<[(Option<OpaqueElement>, &'a Dependency); 1]>;
270type Dependencies<'a, E> = SmallVec<[(E, ElementDependencies<'a>); 1]>;
271type AlreadyInvalidated<'a, E> = SmallVec<[AlreadyInvalidatedEntry<'a, E>; 2]>;
272
273struct AlreadyInvalidatedEntry<'a, E>
274where
275    E: TElement + 'a,
276{
277    /// Element where the invalidation will begin.
278    element: E,
279    /// The current shadow host.
280    host: Option<OpaqueElement>,
281    /// Dependency chain for this invalidation.
282    dependency: &'a Dependency,
283    /// The offset, of the leftmost dependencies that this
284    /// invalidation collapsed. See the `update()` function
285    /// for more information.
286    leftmost_collapse_offset: usize,
287}
288
289impl<'a, E> AlreadyInvalidatedEntry<'a, E>
290where
291    E: TElement + 'a,
292{
293    fn new(element: E, host: Option<OpaqueElement>, dependency: &'a Dependency) -> Self {
294        Self {
295            element,
296            host,
297            dependency,
298            leftmost_collapse_offset: dependency.selector_offset,
299        }
300    }
301
302    /// Update this invalidation with a new invalidation that may collapse with it.
303    fn update(&mut self, element: E, host: Option<OpaqueElement>, dependency: &'a Dependency) {
304        // This dependency should invalidate the same way - Collapse the invalidation
305        // to a more general case so we don't do duplicate work.
306        // e.g. For `:has(.item .item + .item + .item)`, since the anchor would be located
307        // in the ancestor chain for any invalidation triggered by any `.item` compound,
308        // 4 entries can collapse into one - but keep track of the leftmost offset.
309        if self.dependency.selector_offset > dependency.selector_offset {
310            *self = Self {
311                element,
312                host,
313                dependency,
314                leftmost_collapse_offset: self.leftmost_collapse_offset,
315            };
316        } else if self.leftmost_collapse_offset < dependency.selector_offset {
317            self.leftmost_collapse_offset = dependency.selector_offset;
318        }
319    }
320}
321
322/// Interface for collecting relative selector dependencies.
323pub struct RelativeSelectorDependencyCollector<'a, E>
324where
325    E: TElement,
326{
327    /// Dependencies that need to run through the normal invalidation that may generate
328    /// a relative selector invalidation.
329    dependencies: FxHashMap<E, ElementDependencies<'a>>,
330    /// Dependencies that created an invalidation right away.
331    invalidations: AlreadyInvalidated<'a, E>,
332    /// The top element in the subtree being invalidated.
333    top: E,
334    /// Optional context that will be used to try and skip invalidations
335    /// by running selector matches.
336    optimization_context: Option<OptimizationContext<'a, E>>,
337}
338
339type Invalidations<'a> = SmallVec<[RelativeSelectorInvalidation<'a>; 1]>;
340type InnerInvalidations<'a, E> = SmallVec<[(E, RelativeSelectorInvalidation<'a>); 1]>;
341
342struct ToInvalidate<'a, E: TElement + 'a> {
343    /// Dependencies to run through normal invalidator.
344    dependencies: Dependencies<'a, E>,
345    /// Dependencies already invalidated.
346    invalidations: Invalidations<'a>,
347}
348
349impl<'a, E: TElement + 'a> Default for ToInvalidate<'a, E> {
350    fn default() -> Self {
351        Self {
352            dependencies: Dependencies::default(),
353            invalidations: Invalidations::default(),
354        }
355    }
356}
357
358fn invalidation_can_collapse(
359    a: &Dependency,
360    b: &Dependency,
361    allow_indexed_selectors: bool,
362) -> bool {
363    // We want to detect identical dependencies that occur at different
364    // compounds but has the identical compound in the same selector,
365    // e.g. :has(.item .item).
366
367    // If they trigger different invalidations, they shouldn't be collapsed.
368    if a.relative_invalidation_kind() != b.relative_invalidation_kind() {
369        return false;
370    }
371
372    // Not in the same selector, trivially skipped.
373    if SelectorKey::new(&a.selector) != SelectorKey::new(&b.selector) {
374        return false;
375    }
376
377    // Check that this is in the same nesting.
378    // TODO(dshin): @scope probably brings more subtleties...
379    let mut a_next = a.next.as_ref();
380    let mut b_next = b.next.as_ref();
381    while let (Some(a_deps), Some(b_deps)) = (a_next, b_next) {
382        // This is a bit subtle - but we don't need to do the checks we do at higher levels.
383        // Cases like `:is(.item .foo) :is(.item .foo)` where `.item` invalidates would
384        // point to different dependencies, pointing to the same outer selector, but
385        // differing in selector offset.
386        let a_n = &a_deps.as_ref().slice()[0];
387        let b_n = &b_deps.as_ref().slice()[0];
388        if SelectorKey::new(&a_n.selector) != SelectorKey::new(&b_n.selector) {
389            return false;
390        }
391        a_next = a_n.next.as_ref();
392        b_next = b_n.next.as_ref();
393    }
394    if a_next.is_some() || b_next.is_some() {
395        return false;
396    }
397
398    // Ok, now, do the compounds actually match?
399    // This can get expensive quickly, but we're assuming that:
400    //
401    //   * In most cases, authors don't generally duplicate compounds in a selector, so
402    //     this fails quickly
403    //   * In cases where compounds are duplicated, reducing the number of invalidations
404    //     has a payoff that offsets the comparison cost
405    //
406    // Note, `.a.b` != `.b.a` - doesn't affect correctness, though.
407    // TODO(dshin): Caching this may be worth it as well?
408    let mut a_iter = a.selector.iter_from(a.selector_offset);
409    let mut b_iter = b.selector.iter_from(b.selector_offset);
410    loop {
411        let a_component = a_iter.next();
412        let b_component = b_iter.next();
413
414        if a_component != b_component {
415            return false;
416        }
417        let Some(component) = a_component else {
418            return true;
419        };
420        if !allow_indexed_selectors && component.has_indexed_selector_in_subject() {
421            // The element's positioning matters, so can't collapse.
422            return false;
423        }
424    }
425}
426
427impl<'a, E> RelativeSelectorDependencyCollector<'a, E>
428where
429    E: TElement,
430{
431    fn new(top: E, optimization_context: Option<OptimizationContext<'a, E>>) -> Self {
432        Self {
433            dependencies: FxHashMap::default(),
434            invalidations: AlreadyInvalidated::default(),
435            top,
436            optimization_context,
437        }
438    }
439
440    fn insert_invalidation(
441        &mut self,
442        element: E,
443        dependency: &'a Dependency,
444        host: Option<OpaqueElement>,
445    ) {
446        let in_subtree = element != self.top;
447        if let Some(entry) = self.invalidations.iter_mut().find(|entry| {
448            // If we're in the subtree of DOM manipulation - worrying the about positioning of this element
449            // is irrelevant, because the DOM structure is either completely new or about to go away.
450            let both_in_subtree = in_subtree && entry.element != self.top;
451            // If we're considering the same element for invalidation, their evaluation of the indexed selector
452            // is identical by definition.
453            let same_element = element == entry.element;
454            invalidation_can_collapse(
455                dependency,
456                entry.dependency,
457                both_in_subtree || same_element,
458            )
459        }) {
460            entry.update(element, host, dependency)
461        } else {
462            self.invalidations
463                .push(AlreadyInvalidatedEntry::new(element, host, dependency));
464        }
465    }
466
467    /// Add this dependency, if it is unique (i.e. Different outer dependency or same outer dependency
468    /// but requires a different invalidation traversal).
469    pub fn add_dependency(
470        &mut self,
471        dependency: &'a Dependency,
472        element: E,
473        host: Option<OpaqueElement>,
474    ) {
475        match dependency.invalidation_kind() {
476            DependencyInvalidationKind::FullSelector => unreachable!(),
477            DependencyInvalidationKind::Normal(..) | DependencyInvalidationKind::Scope(..) => {
478                self.dependencies
479                    .entry(element)
480                    .and_modify(|v| v.push((host, dependency)))
481                    .or_default()
482                    .push((host, dependency));
483            },
484            DependencyInvalidationKind::Relative(kind) => {
485                debug_assert!(
486                    dependency.next.is_some(),
487                    "Orphaned inner relative selector?"
488                );
489                if element != self.top
490                    && matches!(
491                        kind,
492                        RelativeDependencyInvalidationKind::Parent
493                            | RelativeDependencyInvalidationKind::PrevSibling
494                            | RelativeDependencyInvalidationKind::EarlierSibling
495                    )
496                {
497                    return;
498                }
499                self.insert_invalidation(element, dependency, host);
500            },
501        };
502    }
503
504    /// Get the dependencies in a list format.
505    fn get(self) -> ToInvalidate<'a, E> {
506        let mut result = ToInvalidate::default();
507        for invalidation in self.invalidations {
508            match invalidation.dependency.invalidation_kind() {
509                DependencyInvalidationKind::FullSelector => unreachable!(),
510                DependencyInvalidationKind::Normal(_) | DependencyInvalidationKind::Scope(_) =>
511                    unreachable!("Inner selector in invalidation?"),
512                DependencyInvalidationKind::Relative(kind) => {
513                    if let Some(context) = self.optimization_context.as_ref() {
514                        if context.can_be_ignored(
515                            invalidation.element != self.top,
516                            invalidation.element,
517                            invalidation.host,
518                            invalidation.dependency,
519                            invalidation.leftmost_collapse_offset,
520                        ) {
521                            continue;
522                        }
523                    }
524                    let dependency = &invalidation.dependency.next.as_ref().unwrap().slice()[0];
525                    result.invalidations.push(RelativeSelectorInvalidation {
526                        kind,
527                        host: invalidation.host,
528                        dependency,
529                    });
530                    // We move the invalidation up to the top of the subtree to avoid unnecessary traveral, but
531                    // this means that we need to take ancestor-earlier sibling invalidations into account, as
532                    // they'd look into earlier siblings of the top of the subtree as well.
533                    if invalidation.element != self.top
534                        && matches!(
535                            kind,
536                            RelativeDependencyInvalidationKind::AncestorEarlierSibling
537                                | RelativeDependencyInvalidationKind::AncestorPrevSibling
538                        )
539                    {
540                        result.invalidations.push(RelativeSelectorInvalidation {
541                            kind: if matches!(
542                                kind,
543                                RelativeDependencyInvalidationKind::AncestorPrevSibling
544                            ) {
545                                RelativeDependencyInvalidationKind::PrevSibling
546                            } else {
547                                RelativeDependencyInvalidationKind::EarlierSibling
548                            },
549                            host: invalidation.host,
550                            dependency,
551                        });
552                    }
553                },
554            };
555        }
556        for (key, element_dependencies) in self.dependencies {
557            // At least for now, we don't try to optimize away dependencies emitted from nested selectors.
558            result.dependencies.push((key, element_dependencies));
559        }
560        result
561    }
562
563    fn collect_all_dependencies_for_element(
564        &mut self,
565        element: E,
566        scope: Option<OpaqueElement>,
567        quirks_mode: QuirksMode,
568        map: &'a InvalidationMap,
569        additional_relative_selector_invalidation_map: &'a AdditionalRelativeSelectorInvalidationMap,
570        operation: DomMutationOperation,
571    ) {
572        element
573            .id()
574            .map(|v| match map.id_to_selector.get(v, quirks_mode) {
575                Some(v) => {
576                    for dependency in v {
577                        if !operation.accept(dependency, element) {
578                            continue;
579                        }
580                        self.add_dependency(dependency, element, scope);
581                    }
582                },
583                None => (),
584            });
585        element.each_class(|v| match map.class_to_selector.get(v, quirks_mode) {
586            Some(v) => {
587                for dependency in v {
588                    if !operation.accept(dependency, element) {
589                        continue;
590                    }
591                    self.add_dependency(dependency, element, scope);
592                }
593            },
594            None => (),
595        });
596        element.each_custom_state(|v| match map.custom_state_affecting_selectors.get(v) {
597            Some(v) => {
598                for dependency in v {
599                    if !operation.accept(dependency, element) {
600                        continue;
601                    }
602                    self.add_dependency(dependency, element, scope);
603                }
604            },
605            None => (),
606        });
607        element.each_attr_name(|v| match map.other_attribute_affecting_selectors.get(v) {
608            Some(v) => {
609                for dependency in v {
610                    if !operation.accept(dependency, element) {
611                        continue;
612                    }
613                    self.add_dependency(dependency, element, scope);
614                }
615            },
616            None => (),
617        });
618        let state = element.state();
619        map.state_affecting_selectors.lookup_with_additional(
620            element,
621            quirks_mode,
622            None,
623            &[],
624            ElementState::empty(),
625            |dependency| {
626                if !dependency.state.intersects(state) {
627                    return true;
628                }
629                if !operation.accept(&dependency.dep, element) {
630                    return true;
631                }
632                self.add_dependency(&dependency.dep, element, scope);
633                true
634            },
635        );
636
637        additional_relative_selector_invalidation_map
638            .ts_state_to_selector
639            .lookup_with_additional(
640                element,
641                quirks_mode,
642                None,
643                &[],
644                ElementState::empty(),
645                |dependency| {
646                    if !operation.accept(&dependency.dep, element) {
647                        return true;
648                    }
649                    // This section contain potential optimization for not running full invalidation -
650                    // consult documentation in `TSStateForInvalidation`.
651                    if dependency.state.may_be_optimized() {
652                        if operation.is_side_effect() {
653                            // Side effect operations act on element not being mutated, so they can't
654                            // change the match outcome of these optimizable pseudoclasses.
655                            return true;
656                        }
657                        debug_assert!(
658                            self.optimization_context.is_some(),
659                            "Optimization context not available for DOM mutation?"
660                        );
661                        if dependency.state.contains(TSStateForInvalidation::EMPTY)
662                            && element.first_element_child().is_some()
663                        {
664                            return true;
665                        }
666
667                        let sibling_traversal_map = self
668                            .optimization_context
669                            .as_ref()
670                            .unwrap()
671                            .sibling_traversal_map;
672                        if dependency
673                            .state
674                            .contains(TSStateForInvalidation::NTH_EDGE_FIRST)
675                            && sibling_traversal_map.prev_sibling_for(&element).is_some()
676                        {
677                            return true;
678                        }
679
680                        if dependency
681                            .state
682                            .contains(TSStateForInvalidation::NTH_EDGE_LAST)
683                            && sibling_traversal_map.next_sibling_for(&element).is_some()
684                        {
685                            return true;
686                        }
687                    }
688                    self.add_dependency(&dependency.dep, element, scope);
689                    true
690                },
691            );
692
693        if let Some(v) = additional_relative_selector_invalidation_map
694            .type_to_selector
695            .get(element.local_name())
696        {
697            for dependency in v {
698                if !operation.accept(dependency, element) {
699                    continue;
700                }
701                self.add_dependency(dependency, element, scope);
702            }
703        }
704
705        for dependency in &additional_relative_selector_invalidation_map.any_to_selector {
706            if !operation.accept(dependency, element) {
707                continue;
708            }
709            self.add_dependency(dependency, element, scope);
710        }
711    }
712
713    fn is_empty(&self) -> bool {
714        self.invalidations.is_empty() && self.dependencies.is_empty()
715    }
716}
717
718impl<'a, 'b, E> RelativeSelectorInvalidator<'a, 'b, E>
719where
720    E: TElement + 'a,
721{
722    /// Gather relative selector dependencies for the given element, and invalidate as necessary.
723    #[inline(never)]
724    pub fn invalidate_relative_selectors_for_this<F>(
725        self,
726        stylist: &'a Stylist,
727        mut gather_dependencies: F,
728    ) where
729        F: FnMut(
730            &E,
731            Option<OpaqueElement>,
732            &'a CascadeData,
733            QuirksMode,
734            &mut RelativeSelectorDependencyCollector<'a, E>,
735        ),
736    {
737        let mut collector = RelativeSelectorDependencyCollector::new(self.element, None);
738        stylist.for_each_cascade_data_with_scope(self.element, |data, scope| {
739            let map = data.relative_invalidation_map_attributes();
740            if !map.used {
741                return;
742            }
743            gather_dependencies(
744                &self.element,
745                scope.map(|e| e.opaque()),
746                data,
747                self.quirks_mode,
748                &mut collector,
749            );
750        });
751        if collector.is_empty() {
752            return;
753        }
754        self.invalidate_from_dependencies(collector.get());
755    }
756
757    /// Gather relative selector dependencies for the given element (And its subtree) that mutated, and invalidate as necessary.
758    #[inline(never)]
759    pub fn invalidate_relative_selectors_for_dom_mutation(
760        self,
761        subtree: bool,
762        stylist: &'a Stylist,
763        inherited_search_path: ElementSelectorFlags,
764        operation: DomMutationOperation,
765    ) {
766        let mut collector = RelativeSelectorDependencyCollector::new(
767            self.element,
768            if operation.is_side_effect() {
769                None
770            } else {
771                Some(OptimizationContext {
772                    sibling_traversal_map: &self.sibling_traversal_map,
773                    quirks_mode: self.quirks_mode,
774                    operation,
775                })
776            },
777        );
778        let mut traverse_subtree = false;
779        self.element.apply_selector_flags(inherited_search_path);
780        stylist.for_each_cascade_data_with_scope(self.element, |data, scope| {
781            let map_attributes = data.relative_invalidation_map_attributes();
782            if !map_attributes.used {
783                return;
784            }
785            let map = data.relative_selector_invalidation_map();
786            traverse_subtree |= map_attributes.needs_ancestors_traversal;
787            collector.collect_all_dependencies_for_element(
788                self.element,
789                scope.map(|e| e.opaque()),
790                self.quirks_mode,
791                map,
792                map_attributes,
793                operation,
794            );
795        });
796
797        if subtree && traverse_subtree {
798            for node in self.element.as_node().dom_descendants() {
799                let descendant = match node.as_element() {
800                    Some(e) => e,
801                    None => continue,
802                };
803                descendant.apply_selector_flags(inherited_search_path);
804                stylist.for_each_cascade_data_with_scope(descendant, |data, scope| {
805                    let map_attributes = data.relative_invalidation_map_attributes();
806                    if !map_attributes.used {
807                        return;
808                    }
809                    let map = data.relative_selector_invalidation_map();
810                    collector.collect_all_dependencies_for_element(
811                        descendant,
812                        scope.map(|e| e.opaque()),
813                        self.quirks_mode,
814                        map,
815                        map_attributes,
816                        operation,
817                    );
818                });
819            }
820        }
821        if collector.is_empty() {
822            return;
823        }
824        self.invalidate_from_dependencies(collector.get());
825    }
826
827    /// Carry out complete invalidation triggered by a relative selector invalidation.
828    fn invalidate_from_dependencies(&self, to_invalidate: ToInvalidate<'a, E>) {
829        for (element, dependencies) in to_invalidate.dependencies {
830            let mut selector_caches = SelectorCaches::default();
831            let mut processor = RelativeSelectorInnerInvalidationProcessor::new(
832                self.quirks_mode,
833                self.snapshot_table,
834                &dependencies,
835                &mut selector_caches,
836                &self.sibling_traversal_map,
837            );
838            TreeStyleInvalidator::new(element, None, &mut processor).invalidate();
839            for (element, invalidation) in processor.take_invalidations() {
840                self.invalidate_upwards(element, &invalidation);
841            }
842        }
843        for invalidation in to_invalidate.invalidations {
844            self.invalidate_upwards(self.element, &invalidation);
845        }
846    }
847
848    fn invalidate_upwards(&self, element: E, invalidation: &RelativeSelectorInvalidation<'a>) {
849        // This contains the main reason for why relative selector invalidation is handled
850        // separately - It travels ancestor and/or earlier sibling direction.
851        match invalidation.kind {
852            RelativeDependencyInvalidationKind::Parent => {
853                element.parent_element().map(|e| {
854                    if !Self::in_search_direction(
855                        &e,
856                        ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR,
857                    ) {
858                        return;
859                    }
860                    self.handle_anchor(e, invalidation.dependency, invalidation.host);
861                });
862            },
863            RelativeDependencyInvalidationKind::Ancestors => {
864                let mut parent = element.parent_element();
865                while let Some(par) = parent {
866                    if !Self::in_search_direction(
867                        &par,
868                        ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR,
869                    ) {
870                        return;
871                    }
872                    self.handle_anchor(par, invalidation.dependency, invalidation.host);
873                    parent = par.parent_element();
874                }
875            },
876            RelativeDependencyInvalidationKind::PrevSibling => {
877                self.sibling_traversal_map
878                    .prev_sibling_for(&element)
879                    .map(|e| {
880                        if !Self::in_search_direction(
881                            &e,
882                            ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_SIBLING,
883                        ) {
884                            return;
885                        }
886                        self.handle_anchor(e, invalidation.dependency, invalidation.host);
887                    });
888            },
889            RelativeDependencyInvalidationKind::AncestorPrevSibling => {
890                let mut parent = element.parent_element();
891                while let Some(par) = parent {
892                    if !Self::in_search_direction(
893                        &par,
894                        ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR,
895                    ) {
896                        return;
897                    }
898                    par.prev_sibling_element().map(|e| {
899                        if !Self::in_search_direction(
900                            &e,
901                            ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_SIBLING,
902                        ) {
903                            return;
904                        }
905                        self.handle_anchor(e, invalidation.dependency, invalidation.host);
906                    });
907                    parent = par.parent_element();
908                }
909            },
910            RelativeDependencyInvalidationKind::EarlierSibling => {
911                let mut sibling = self.sibling_traversal_map.prev_sibling_for(&element);
912                while let Some(sib) = sibling {
913                    if !Self::in_search_direction(
914                        &sib,
915                        ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_SIBLING,
916                    ) {
917                        return;
918                    }
919                    self.handle_anchor(sib, invalidation.dependency, invalidation.host);
920                    sibling = sib.prev_sibling_element();
921                }
922            },
923            RelativeDependencyInvalidationKind::AncestorEarlierSibling => {
924                let mut parent = element.parent_element();
925                while let Some(par) = parent {
926                    if !Self::in_search_direction(
927                        &par,
928                        ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR,
929                    ) {
930                        return;
931                    }
932                    let mut sibling = par.prev_sibling_element();
933                    while let Some(sib) = sibling {
934                        if !Self::in_search_direction(
935                            &sib,
936                            ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_SIBLING,
937                        ) {
938                            return;
939                        }
940                        self.handle_anchor(sib, invalidation.dependency, invalidation.host);
941                        sibling = sib.prev_sibling_element();
942                    }
943                    parent = par.parent_element();
944                }
945            },
946        }
947    }
948
949    /// Is this element in the direction of the given relative selector search path?
950    fn in_search_direction(element: &E, desired: ElementSelectorFlags) -> bool {
951        element
952            .relative_selector_search_direction()
953            .intersects(desired)
954    }
955
956    /// Handle a potential relative selector anchor.
957    fn handle_anchor(
958        &self,
959        element: E,
960        outer_dependency: &Dependency,
961        host: Option<OpaqueElement>,
962    ) {
963        let is_rightmost = Self::is_subject(outer_dependency);
964        if (is_rightmost
965            && !element.has_selector_flags(ElementSelectorFlags::ANCHORS_RELATIVE_SELECTOR))
966            || (!is_rightmost
967                && !element.has_selector_flags(
968                    ElementSelectorFlags::ANCHORS_RELATIVE_SELECTOR_NON_SUBJECT,
969                ))
970        {
971            // If it was never a relative selector anchor, don't bother.
972            return;
973        }
974        let mut selector_caches = SelectorCaches::default();
975        let matching_context = MatchingContext::<'_, E::Impl>::new_for_visited(
976            MatchingMode::Normal,
977            None,
978            &mut selector_caches,
979            VisitedHandlingMode::AllLinksVisitedAndUnvisited,
980            IncludeStartingStyle::No,
981            self.quirks_mode,
982            NeedsSelectorFlags::No,
983            MatchingForInvalidation::Yes,
984        );
985        let mut data = match element.mutate_data() {
986            Some(data) => data,
987            None => return,
988        };
989        let mut processor = RelativeSelectorOuterInvalidationProcessor {
990            element,
991            host,
992            data: data.deref_mut(),
993            dependency: &*outer_dependency,
994            matching_context,
995            traversal_map: &self.sibling_traversal_map,
996        };
997        let result = TreeStyleInvalidator::new(element, None, &mut processor).invalidate();
998        (self.invalidated)(element, &result);
999    }
1000
1001    /// Does this relative selector dependency have its relative selector in the subject position?
1002    fn is_subject(outer_dependency: &Dependency) -> bool {
1003        debug_assert!(
1004            matches!(
1005                outer_dependency.invalidation_kind(),
1006                DependencyInvalidationKind::Normal(_)
1007            ),
1008            "Outer selector of relative selector is relative?"
1009        );
1010
1011        if let Some(x) = outer_dependency.next.as_ref() {
1012            if !Self::is_subject(&x.as_ref().slice()[0]) {
1013                // Not subject in outer selector.
1014                return false;
1015            }
1016        }
1017        outer_dependency
1018            .selector
1019            .is_rightmost(outer_dependency.selector_offset)
1020    }
1021}
1022
1023/// Blindly invalidate everything outside of a relative selector.
1024/// Consider `:is(.a :has(.b) .c ~ .d) ~ .e .f`, where .b gets deleted.
1025/// Since the tree mutated, we cannot rely on snapshots.
1026pub struct RelativeSelectorOuterInvalidationProcessor<'a, 'b, E: TElement> {
1027    /// Element being invalidated.
1028    pub element: E,
1029    /// The current shadow host, if any.
1030    pub host: Option<OpaqueElement>,
1031    /// Data for the element being invalidated.
1032    pub data: &'a mut ElementData,
1033    /// Dependency to be processed.
1034    pub dependency: &'b Dependency,
1035    /// Matching context to use for invalidation.
1036    pub matching_context: MatchingContext<'a, E::Impl>,
1037    /// Traversal map for this invalidation.
1038    pub traversal_map: &'a SiblingTraversalMap<E>,
1039}
1040
1041impl<'a, 'b: 'a, E: 'a> InvalidationProcessor<'b, 'a, E>
1042    for RelativeSelectorOuterInvalidationProcessor<'a, 'b, E>
1043where
1044    E: TElement,
1045{
1046    fn invalidates_on_pseudo_element(&self) -> bool {
1047        true
1048    }
1049
1050    fn check_outer_dependency(&mut self, _dependency: &Dependency, _element: E, _: Option<OpaqueElement>) -> bool {
1051        // At this point, we know a relative selector invalidated, and are ignoring them.
1052        true
1053    }
1054
1055    fn matching_context(&mut self) -> &mut MatchingContext<'a, E::Impl> {
1056        &mut self.matching_context
1057    }
1058
1059    fn sibling_traversal_map(&self) -> &SiblingTraversalMap<E> {
1060        self.traversal_map
1061    }
1062
1063    fn collect_invalidations(
1064        &mut self,
1065        element: E,
1066        _self_invalidations: &mut InvalidationVector<'b>,
1067        descendant_invalidations: &mut DescendantInvalidationLists<'b>,
1068        sibling_invalidations: &mut InvalidationVector<'b>,
1069    ) -> bool {
1070        debug_assert_eq!(element, self.element);
1071        debug_assert!(
1072            self.matching_context.matching_for_invalidation(),
1073            "Not matching for invalidation?"
1074        );
1075
1076        // Ok, this element can potentially an anchor to the given dependency.
1077        // Before we do the potentially-costly ancestor/earlier sibling traversal,
1078        // See if it can actuall be an anchor by trying to match the "rest" of the selector
1079        // outside and to the left of `:has` in question.
1080        // e.g. Element under consideration can only be the anchor to `:has` in
1081        // `.foo .bar ~ .baz:has()`, iff it matches `.foo .bar ~ .baz`.
1082        let invalidated_self = {
1083            let mut d = self.dependency;
1084            loop {
1085                debug_assert!(
1086                    matches!(d.invalidation_kind(), DependencyInvalidationKind::Normal(_)),
1087                    "Unexpected dependency kind"
1088                );
1089                if !dependency_may_be_relevant(d, &element, false) {
1090                    break false;
1091                }
1092                if !matches_selector(
1093                    &d.selector,
1094                    d.selector_offset,
1095                    None,
1096                    &element,
1097                    self.matching_context(),
1098                ) {
1099                    break false;
1100                }
1101                let invalidation_kind = d.normal_invalidation_kind();
1102                if matches!(invalidation_kind, NormalDependencyInvalidationKind::Element) {
1103                    if let Some(ref deps) = d.next {
1104                        d = &deps.as_ref().slice()[0];
1105                        continue;
1106                    }
1107                    break true;
1108                }
1109                debug_assert_ne!(d.selector_offset, 0);
1110                debug_assert_ne!(d.selector_offset, d.selector.len());
1111                let invalidation = Invalidation::new(&d, self.host, None);
1112                break push_invalidation(
1113                    invalidation,
1114                    d.invalidation_kind(),
1115                    descendant_invalidations,
1116                    sibling_invalidations,
1117                );
1118            }
1119        };
1120
1121        if invalidated_self {
1122            self.data.hint.insert(RestyleHint::RESTYLE_SELF);
1123        }
1124        invalidated_self
1125    }
1126
1127    fn should_process_descendants(&mut self, element: E) -> bool {
1128        if element == self.element {
1129            return should_process_descendants(&self.data);
1130        }
1131
1132        match element.borrow_data() {
1133            Some(d) => should_process_descendants(&d),
1134            None => return false,
1135        }
1136    }
1137
1138    fn recursion_limit_exceeded(&mut self, _element: E) {
1139        unreachable!("Unexpected recursion limit");
1140    }
1141
1142    fn invalidated_descendants(&mut self, element: E, child: E) {
1143        invalidated_descendants(element, child)
1144    }
1145
1146    fn invalidated_self(&mut self, element: E) {
1147        debug_assert_ne!(element, self.element);
1148        invalidated_self(element);
1149    }
1150
1151    fn invalidated_sibling(&mut self, element: E, of: E) {
1152        debug_assert_ne!(element, self.element);
1153        invalidated_sibling(element, of);
1154    }
1155}
1156
1157/// Invalidation for the selector(s) inside a relative selector.
1158pub struct RelativeSelectorInnerInvalidationProcessor<'a, 'b, 'c, E>
1159where
1160    E: TElement + 'a,
1161{
1162    /// Matching context to be used.
1163    matching_context: MatchingContext<'b, E::Impl>,
1164    /// Table of snapshots.
1165    snapshot_table: Option<&'c ServoElementSnapshotTable>,
1166    /// Incoming dependencies to be processed.
1167    dependencies: &'c ElementDependencies<'a>,
1168    /// Generated invalidations.
1169    invalidations: InnerInvalidations<'a, E>,
1170    /// Traversal map for this invalidation.
1171    traversal_map: &'b SiblingTraversalMap<E>,
1172}
1173
1174impl<'a, 'b, 'c, E> RelativeSelectorInnerInvalidationProcessor<'a, 'b, 'c, E>
1175where
1176    E: TElement + 'a,
1177{
1178    fn new(
1179        quirks_mode: QuirksMode,
1180        snapshot_table: Option<&'c ServoElementSnapshotTable>,
1181        dependencies: &'c ElementDependencies<'a>,
1182        selector_caches: &'b mut SelectorCaches,
1183        traversal_map: &'b SiblingTraversalMap<E>,
1184    ) -> Self {
1185        let matching_context = MatchingContext::new_for_visited(
1186            MatchingMode::Normal,
1187            None,
1188            selector_caches,
1189            VisitedHandlingMode::AllLinksVisitedAndUnvisited,
1190            IncludeStartingStyle::No,
1191            quirks_mode,
1192            NeedsSelectorFlags::No,
1193            MatchingForInvalidation::Yes,
1194        );
1195        Self {
1196            matching_context,
1197            snapshot_table,
1198            dependencies,
1199            invalidations: InnerInvalidations::default(),
1200            traversal_map,
1201        }
1202    }
1203
1204    fn note_dependency(
1205        &mut self,
1206        element: E,
1207        host: Option<OpaqueElement>,
1208        dependency: &'a Dependency,
1209        descendant_invalidations: &mut DescendantInvalidationLists<'a>,
1210        sibling_invalidations: &mut InvalidationVector<'a>,
1211    ) {
1212        match dependency.invalidation_kind() {
1213            DependencyInvalidationKind::FullSelector => unreachable!(),
1214            DependencyInvalidationKind::Normal(_) | DependencyInvalidationKind::Scope(_) => (),
1215            DependencyInvalidationKind::Relative(kind) => {
1216                self.found_relative_selector_invalidation(element, kind, dependency);
1217                return;
1218            },
1219        }
1220        if matches!(
1221            dependency.normal_invalidation_kind(),
1222            NormalDependencyInvalidationKind::Element
1223        ) {
1224            // Ok, keep heading outwards.
1225            debug_assert!(
1226                dependency.next.is_some(),
1227                "Orphaned inner selector dependency?"
1228            );
1229            if let Some(next) = dependency.next.as_ref() {
1230                self.note_dependency(
1231                    element,
1232                    host,
1233                    &next.as_ref().slice()[0],
1234                    descendant_invalidations,
1235                    sibling_invalidations,
1236                );
1237            }
1238            return;
1239        }
1240        let invalidation = Invalidation::new(&dependency, None, None);
1241        match dependency.normal_invalidation_kind() {
1242            NormalDependencyInvalidationKind::Descendants => {
1243                // Descendant invalidations are simplified due to pseudo-elements not being available within the relative selector.
1244                descendant_invalidations.dom_descendants.push(invalidation)
1245            },
1246            NormalDependencyInvalidationKind::Siblings => sibling_invalidations.push(invalidation),
1247            // Note(dshin, bug 1940212): Nesting can enabling stuffing pseudo-elements into :has, like `::marker { :has(&) }`.
1248            // Ideally, we can just not insert the dependency into the invalidation map, but the necessary selector information
1249            // for this (i.e. `HAS_PSEUDO`) is filtered out in `replace_parent_selector` through
1250            // `SelectorFlags::forbidden_for_nesting`, so just ignoring such dependencies here is the best we can do.
1251            _ => (),
1252        }
1253    }
1254
1255    /// Take the generated invalidations.
1256    fn take_invalidations(self) -> InnerInvalidations<'a, E> {
1257        self.invalidations
1258    }
1259}
1260
1261impl<'a, 'b, 'c, E> InvalidationProcessor<'a, 'b, E>
1262    for RelativeSelectorInnerInvalidationProcessor<'a, 'b, 'c, E>
1263where
1264    E: TElement + 'a,
1265{
1266    fn check_outer_dependency(&mut self, dependency: &Dependency, element: E, _: Option<OpaqueElement>) -> bool {
1267        if let Some(snapshot_table) = self.snapshot_table {
1268            let wrapper = ElementWrapper::new(element, snapshot_table);
1269            return check_dependency(dependency, &element, &wrapper, &mut self.matching_context, None);
1270        }
1271        // Just invalidate if we don't have a snapshot.
1272        true
1273    }
1274
1275    fn matching_context(&mut self) -> &mut MatchingContext<'b, E::Impl> {
1276        return &mut self.matching_context;
1277    }
1278
1279    fn collect_invalidations(
1280        &mut self,
1281        element: E,
1282        _self_invalidations: &mut InvalidationVector<'a>,
1283        descendant_invalidations: &mut DescendantInvalidationLists<'a>,
1284        sibling_invalidations: &mut InvalidationVector<'a>,
1285    ) -> bool {
1286        for (scope, dependency) in self.dependencies {
1287            self.note_dependency(
1288                element,
1289                *scope,
1290                dependency,
1291                descendant_invalidations,
1292                sibling_invalidations,
1293            )
1294        }
1295        false
1296    }
1297
1298    fn should_process_descendants(&mut self, _element: E) -> bool {
1299        true
1300    }
1301
1302    fn recursion_limit_exceeded(&mut self, _element: E) {
1303        unreachable!("Unexpected recursion limit");
1304    }
1305
1306    // Don't do anything for normal invalidations.
1307    fn invalidated_self(&mut self, _element: E) {}
1308    fn invalidated_sibling(&mut self, _sibling: E, _of: E) {}
1309    fn invalidated_descendants(&mut self, _element: E, _child: E) {}
1310
1311    fn found_relative_selector_invalidation(
1312        &mut self,
1313        element: E,
1314        kind: RelativeDependencyInvalidationKind,
1315        dep: &'a Dependency,
1316    ) {
1317        debug_assert!(dep.next.is_some(), "Orphaned inners selector?");
1318        if element.relative_selector_search_direction().is_empty() {
1319            return;
1320        }
1321        self.invalidations.push((
1322            element,
1323            RelativeSelectorInvalidation {
1324                host: self.matching_context.current_host,
1325                kind,
1326                dependency: &dep.next.as_ref().unwrap().as_ref().slice()[0],
1327            },
1328        ));
1329    }
1330
1331    fn sibling_traversal_map(&self) -> &SiblingTraversalMap<E> {
1332        &self.traversal_map
1333    }
1334}
style/invalidation/element/relative_selector.rs

style/invalidation/element/
relative_selector.rs
