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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
use crate::attr::{
AttrSelectorOperation, AttrSelectorWithOptionalNamespace, CaseSensitivity, NamespaceConstraint,
ParsedAttrSelectorOperation, ParsedCaseSensitivity,
};
use crate::bloom::{BloomFilter, BLOOM_HASH_MASK};
use crate::kleene_value::KleeneValue;
use crate::parser::{
AncestorHashes, Combinator, Component, LocalName, NthSelectorData, RelativeSelectorMatchHint,
};
use crate::parser::{
NonTSPseudoClass, RelativeSelector, Selector, SelectorImpl, SelectorIter, SelectorList,
};
use crate::relative_selector::cache::RelativeSelectorCachedMatch;
use crate::tree::Element;
use smallvec::SmallVec;
use std::borrow::Borrow;
pub use crate::context::*;
// The bloom filter for descendant CSS selectors will have a <1% false
// positive rate until it has this many selectors in it, then it will
// rapidly increase.
pub static RECOMMENDED_SELECTOR_BLOOM_FILTER_SIZE: usize = 4096;
bitflags! {
/// Set of flags that are set on either the element or its parent (depending
/// on the flag) if the element could potentially match a selector.
#[derive(Clone, Copy)]
pub struct ElementSelectorFlags: usize {
/// When a child is added or removed from the parent, all the children
/// must be restyled, because they may match :nth-last-child,
/// :last-of-type, :nth-last-of-type, or :only-of-type.
const HAS_SLOW_SELECTOR = 1 << 0;
/// When a child is added or removed from the parent, any later
/// children must be restyled, because they may match :nth-child,
/// :first-of-type, or :nth-of-type.
const HAS_SLOW_SELECTOR_LATER_SIBLINGS = 1 << 1;
/// HAS_SLOW_SELECTOR* was set by the presence of :nth (But not of).
const HAS_SLOW_SELECTOR_NTH = 1 << 2;
/// When a DOM mutation occurs on a child that might be matched by
/// :nth-last-child(.. of <selector list>), earlier children must be
/// restyled, and HAS_SLOW_SELECTOR will be set (which normally
/// indicates that all children will be restyled).
///
/// Similarly, when a DOM mutation occurs on a child that might be
/// matched by :nth-child(.. of <selector list>), later children must be
/// restyled, and HAS_SLOW_SELECTOR_LATER_SIBLINGS will be set.
const HAS_SLOW_SELECTOR_NTH_OF = 1 << 3;
/// When a child is added or removed from the parent, the first and
/// last children must be restyled, because they may match :first-child,
/// :last-child, or :only-child.
const HAS_EDGE_CHILD_SELECTOR = 1 << 4;
/// The element has an empty selector, so when a child is appended we
/// might need to restyle the parent completely.
const HAS_EMPTY_SELECTOR = 1 << 5;
/// The element may anchor a relative selector.
const ANCHORS_RELATIVE_SELECTOR = 1 << 6;
/// The element may anchor a relative selector that is not the subject
/// of the whole selector.
const ANCHORS_RELATIVE_SELECTOR_NON_SUBJECT = 1 << 7;
/// The element is reached by a relative selector search in the sibling direction.
const RELATIVE_SELECTOR_SEARCH_DIRECTION_SIBLING = 1 << 8;
/// The element is reached by a relative selector search in the ancestor direction.
const RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR = 1 << 9;
// The element is reached by a relative selector search in both sibling and ancestor directions.
const RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR_SIBLING =
Self::RELATIVE_SELECTOR_SEARCH_DIRECTION_SIBLING.bits() |
Self::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR.bits();
}
}
impl ElementSelectorFlags {
/// Returns the subset of flags that apply to the element.
pub fn for_self(self) -> ElementSelectorFlags {
self & (ElementSelectorFlags::HAS_EMPTY_SELECTOR |
ElementSelectorFlags::ANCHORS_RELATIVE_SELECTOR |
ElementSelectorFlags::ANCHORS_RELATIVE_SELECTOR_NON_SUBJECT |
ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_SIBLING |
ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR)
}
/// Returns the subset of flags that apply to the parent.
pub fn for_parent(self) -> ElementSelectorFlags {
self & (ElementSelectorFlags::HAS_SLOW_SELECTOR |
ElementSelectorFlags::HAS_SLOW_SELECTOR_LATER_SIBLINGS |
ElementSelectorFlags::HAS_SLOW_SELECTOR_NTH |
ElementSelectorFlags::HAS_SLOW_SELECTOR_NTH_OF |
ElementSelectorFlags::HAS_EDGE_CHILD_SELECTOR)
}
}
/// Holds per-compound-selector data.
struct LocalMatchingContext<'a, 'b: 'a, Impl: SelectorImpl> {
shared: &'a mut MatchingContext<'b, Impl>,
rightmost: SubjectOrPseudoElement,
quirks_data: Option<SelectorIter<'a, Impl>>,
}
#[inline(always)]
pub fn matches_selector_list<E>(
selector_list: &SelectorList<E::Impl>,
element: &E,
context: &mut MatchingContext<E::Impl>,
) -> bool
where
E: Element,
{
// This is pretty much any(..) but manually inlined because the compiler
// refuses to do so from querySelector / querySelectorAll.
for selector in selector_list.slice() {
let matches = matches_selector(selector, 0, None, element, context);
if matches {
return true;
}
}
false
}
#[inline(always)]
fn may_match(hashes: &AncestorHashes, bf: &BloomFilter) -> bool {
// Check the first three hashes. Note that we can check for zero before
// masking off the high bits, since if any of the first three hashes is
// zero the fourth will be as well. We also take care to avoid the
// special-case complexity of the fourth hash until we actually reach it,
// because we usually don't.
//
// To be clear: this is all extremely hot.
for i in 0..3 {
let packed = hashes.packed_hashes[i];
if packed == 0 {
// No more hashes left - unable to fast-reject.
return true;
}
if !bf.might_contain_hash(packed & BLOOM_HASH_MASK) {
// Hooray! We fast-rejected on this hash.
return false;
}
}
// Now do the slighty-more-complex work of synthesizing the fourth hash,
// and check it against the filter if it exists.
let fourth = hashes.fourth_hash();
fourth == 0 || bf.might_contain_hash(fourth)
}
/// A result of selector matching, includes 3 failure types,
///
/// NotMatchedAndRestartFromClosestLaterSibling
/// NotMatchedAndRestartFromClosestDescendant
/// NotMatchedGlobally
///
/// When NotMatchedGlobally appears, stop selector matching completely since
/// the succeeding selectors never matches.
/// It is raised when
/// Child combinator cannot find the candidate element.
/// Descendant combinator cannot find the candidate element.
///
/// When NotMatchedAndRestartFromClosestDescendant appears, the selector
/// matching does backtracking and restarts from the closest Descendant
/// combinator.
/// It is raised when
/// NextSibling combinator cannot find the candidate element.
/// LaterSibling combinator cannot find the candidate element.
/// Child combinator doesn't match on the found element.
///
/// When NotMatchedAndRestartFromClosestLaterSibling appears, the selector
/// matching does backtracking and restarts from the closest LaterSibling
/// combinator.
/// It is raised when
/// NextSibling combinator doesn't match on the found element.
///
/// For example, when the selector "d1 d2 a" is provided and we cannot *find*
/// an appropriate ancestor element for "d1", this selector matching raises
/// NotMatchedGlobally since even if "d2" is moved to more upper element, the
/// candidates for "d1" becomes less than before and d1 .
///
/// The next example is siblings. When the selector "b1 + b2 ~ d1 a" is
/// provided and we cannot *find* an appropriate brother element for b1,
/// the selector matching raises NotMatchedAndRestartFromClosestDescendant.
/// The selectors ("b1 + b2 ~") doesn't match and matching restart from "d1".
///
/// The additional example is child and sibling. When the selector
/// "b1 + c1 > b2 ~ d1 a" is provided and the selector "b1" doesn't match on
/// the element, this "b1" raises NotMatchedAndRestartFromClosestLaterSibling.
/// However since the selector "c1" raises
/// NotMatchedAndRestartFromClosestDescendant. So the selector
/// "b1 + c1 > b2 ~ " doesn't match and restart matching from "d1".
///
/// There is also the unknown result, which is used during invalidation when
/// specific selector is being tested for before/after comparison. More specifically,
/// selectors that are too expensive to correctly compute during invalidation may
/// return unknown, as the computation will be thrown away and only to be recomputed
/// during styling. For most cases, the unknown result can be treated as matching.
/// This is because a compound of selectors acts like &&, and unknown && matched
/// == matched and unknown && not-matched == not-matched. However, some selectors,
/// like `:is()`, behave like || i.e. `:is(.a, .b)` == a || b. Treating unknown
/// == matching then causes these selectors to always return matching, which undesired
/// for before/after comparison. Coercing to not-matched doesn't work since each
/// inner selector may have compounds: e.g. Toggling `.foo` in `:is(.foo:has(..))`
/// with coersion to not-matched would result in an invalid before/after comparison
/// of not-matched/not-matched.
#[derive(Clone, Copy, Eq, PartialEq)]
enum SelectorMatchingResult {
Matched,
NotMatchedAndRestartFromClosestLaterSibling,
NotMatchedAndRestartFromClosestDescendant,
NotMatchedGlobally,
Unknown,
}
impl From<SelectorMatchingResult> for KleeneValue {
fn from(value: SelectorMatchingResult) -> Self {
match value {
SelectorMatchingResult::Matched => KleeneValue::True,
SelectorMatchingResult::Unknown => KleeneValue::Unknown,
SelectorMatchingResult::NotMatchedAndRestartFromClosestLaterSibling |
SelectorMatchingResult::NotMatchedAndRestartFromClosestDescendant |
SelectorMatchingResult::NotMatchedGlobally => KleeneValue::False,
}
}
}
/// Matches a selector, fast-rejecting against a bloom filter.
///
/// We accept an offset to allow consumers to represent and match against
/// partial selectors (indexed from the right). We use this API design, rather
/// than having the callers pass a SelectorIter, because creating a SelectorIter
/// requires dereferencing the selector to get the length, which adds an
/// unncessary cache miss for cases when we can fast-reject with AncestorHashes
/// (which the caller can store inline with the selector pointer).
#[inline(always)]
pub fn matches_selector<E>(
selector: &Selector<E::Impl>,
offset: usize,
hashes: Option<&AncestorHashes>,
element: &E,
context: &mut MatchingContext<E::Impl>,
) -> bool
where
E: Element,
{
let result = matches_selector_kleene(selector, offset, hashes, element, context);
if cfg!(debug_assertions) && result == KleeneValue::Unknown {
debug_assert!(
context.matching_for_invalidation_comparison().unwrap_or(false),
"How did we return unknown?"
);
}
result.to_bool(true)
}
/// Same as matches_selector, but returns the Kleene value as-is.
#[inline(always)]
pub fn matches_selector_kleene<E>(
selector: &Selector<E::Impl>,
offset: usize,
hashes: Option<&AncestorHashes>,
element: &E,
context: &mut MatchingContext<E::Impl>,
) -> KleeneValue
where
E: Element,
{
// Use the bloom filter to fast-reject.
if let Some(hashes) = hashes {
if let Some(filter) = context.bloom_filter {
if !may_match(hashes, filter) {
return KleeneValue::False;
}
}
}
matches_complex_selector(
selector.iter_from(offset),
element,
context,
if selector.is_rightmost(offset) {
SubjectOrPseudoElement::Yes
} else {
SubjectOrPseudoElement::No
},
)
}
/// Whether a compound selector matched, and whether it was the rightmost
/// selector inside the complex selector.
pub enum CompoundSelectorMatchingResult {
/// The selector was fully matched.
FullyMatched,
/// The compound selector matched, and the next combinator offset is
/// `next_combinator_offset`.
Matched { next_combinator_offset: usize },
/// The selector didn't match.
NotMatched,
}
/// Matches a compound selector belonging to `selector`, starting at offset
/// `from_offset`, matching left to right.
///
/// Requires that `from_offset` points to a `Combinator`.
///
/// NOTE(emilio): This doesn't allow to match in the leftmost sequence of the
/// complex selector, but it happens to be the case we don't need it.
pub fn matches_compound_selector_from<E>(
selector: &Selector<E::Impl>,
mut from_offset: usize,
context: &mut MatchingContext<E::Impl>,
element: &E,
) -> CompoundSelectorMatchingResult
where
E: Element,
{
debug_assert!(
!context
.matching_for_invalidation_comparison()
.unwrap_or(false),
"CompoundSelectorMatchingResult doesn't support unknown"
);
if cfg!(debug_assertions) && from_offset != 0 {
selector.combinator_at_parse_order(from_offset - 1); // This asserts.
}
let mut local_context = LocalMatchingContext {
shared: context,
// We have no info if this is an outer selector. This function is called in
// an invalidation context, which only calls this for non-subject (i.e.
// Non-rightmost) positions.
rightmost: SubjectOrPseudoElement::No,
quirks_data: None,
};
// Find the end of the selector or the next combinator, then match
// backwards, so that we match in the same order as
// matches_complex_selector, which is usually faster.
let start_offset = from_offset;
for component in selector.iter_raw_parse_order_from(from_offset) {
if matches!(*component, Component::Combinator(..)) {
debug_assert_ne!(from_offset, 0, "Selector started with a combinator?");
break;
}
from_offset += 1;
}
debug_assert!(from_offset >= 1);
debug_assert!(from_offset <= selector.len());
let iter = selector.iter_from(selector.len() - from_offset);
debug_assert!(
iter.clone().next().is_some() ||
(from_offset != selector.len() &&
matches!(
selector.combinator_at_parse_order(from_offset),
Combinator::SlotAssignment | Combinator::PseudoElement
)),
"Got the math wrong: {:?} | {:?} | {} {}",
selector,
selector.iter_raw_match_order().as_slice(),
from_offset,
start_offset
);
for component in iter {
let result = matches_simple_selector(component, element, &mut local_context);
debug_assert!(result != KleeneValue::Unknown, "Returned unknown in non invalidation context?");
if !result.to_bool(true) {
return CompoundSelectorMatchingResult::NotMatched;
}
}
if from_offset != selector.len() {
return CompoundSelectorMatchingResult::Matched {
next_combinator_offset: from_offset,
};
}
CompoundSelectorMatchingResult::FullyMatched
}
/// Matches a complex selector.
#[inline(always)]
fn matches_complex_selector<E>(
mut iter: SelectorIter<E::Impl>,
element: &E,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
) -> KleeneValue
where
E: Element,
{
// If this is the special pseudo-element mode, consume the ::pseudo-element
// before proceeding, since the caller has already handled that part.
if context.matching_mode() == MatchingMode::ForStatelessPseudoElement && !context.is_nested() {
// Consume the pseudo.
match *iter.next().unwrap() {
Component::PseudoElement(ref pseudo) => {
if let Some(ref f) = context.pseudo_element_matching_fn {
if !f(pseudo) {
return KleeneValue::False;
}
}
},
ref other => {
debug_assert!(
false,
"Used MatchingMode::ForStatelessPseudoElement \
in a non-pseudo selector {:?}",
other
);
return KleeneValue::False;
},
}
if !iter.matches_for_stateless_pseudo_element() {
return KleeneValue::False;
}
// Advance to the non-pseudo-element part of the selector.
let next_sequence = iter.next_sequence().unwrap();
debug_assert_eq!(next_sequence, Combinator::PseudoElement);
}
matches_complex_selector_internal(
iter,
element,
context,
rightmost,
SubjectOrPseudoElement::Yes,
)
.into()
}
/// Matches each selector of a list as a complex selector
fn matches_complex_selector_list<E: Element>(
list: &[Selector<E::Impl>],
element: &E,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
) -> KleeneValue {
KleeneValue::any(
list.iter(),
|selector| matches_complex_selector(
selector.iter(),
element,
context,
rightmost
)
)
}
fn matches_relative_selector<E: Element>(
relative_selector: &RelativeSelector<E::Impl>,
element: &E,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
) -> bool {
// Overall, we want to mark the path that we've traversed so that when an element
// is invalidated, we early-reject unnecessary relative selector invalidations.
if relative_selector.match_hint.is_descendant_direction() {
if context.needs_selector_flags() {
element.apply_selector_flags(
ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR,
);
}
let mut next_element = element.first_element_child();
while let Some(el) = next_element {
if context.needs_selector_flags() {
el.apply_selector_flags(
ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR,
);
}
let mut matched = matches_complex_selector(
relative_selector.selector.iter(),
&el,
context,
rightmost,
)
.to_bool(true);
if !matched && relative_selector.match_hint.is_subtree() {
matched = matches_relative_selector_subtree(
&relative_selector.selector,
&el,
context,
rightmost,
);
}
if matched {
return true;
}
next_element = el.next_sibling_element();
}
} else {
debug_assert!(
matches!(
relative_selector.match_hint,
RelativeSelectorMatchHint::InNextSibling |
RelativeSelectorMatchHint::InNextSiblingSubtree |
RelativeSelectorMatchHint::InSibling |
RelativeSelectorMatchHint::InSiblingSubtree
),
"Not descendant direction, but also not sibling direction?"
);
if context.needs_selector_flags() {
element.apply_selector_flags(
ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_SIBLING,
);
}
let sibling_flag = if relative_selector.match_hint.is_subtree() {
ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR_SIBLING
} else {
ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_SIBLING
};
let mut next_element = element.next_sibling_element();
while let Some(el) = next_element {
if context.needs_selector_flags() {
el.apply_selector_flags(sibling_flag);
}
let matched = if relative_selector.match_hint.is_subtree() {
matches_relative_selector_subtree(
&relative_selector.selector,
&el,
context,
rightmost,
)
} else {
matches_complex_selector(relative_selector.selector.iter(), &el, context, rightmost)
.to_bool(true)
};
if matched {
return true;
}
if relative_selector.match_hint.is_next_sibling() {
break;
}
next_element = el.next_sibling_element();
}
}
return false;
}
fn relative_selector_match_early<E: Element>(
selector: &RelativeSelector<E::Impl>,
element: &E,
context: &mut MatchingContext<E::Impl>,
) -> Option<bool> {
// See if we can return a cached result.
if let Some(cached) = context
.selector_caches
.relative_selector
.lookup(element.opaque(), selector)
{
return Some(cached.matched());
}
// See if we can fast-reject.
if context
.selector_caches
.relative_selector_filter_map
.fast_reject(element, selector, context.quirks_mode())
{
// Alright, add as unmatched to cache.
context.selector_caches.relative_selector.add(
element.opaque(),
selector,
RelativeSelectorCachedMatch::NotMatched,
);
return Some(false);
}
None
}
fn match_relative_selectors<E: Element>(
selectors: &[RelativeSelector<E::Impl>],
element: &E,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
) -> KleeneValue {
if context.relative_selector_anchor().is_some() {
// FIXME(emilio): This currently can happen with nesting, and it's not fully
// correct, arguably. But the ideal solution isn't super-clear either. For now,
// cope with it and explicitly reject it at match time. See [1] for discussion.
//
return KleeneValue::False;
}
if let Some(may_return_unknown) = context.matching_for_invalidation_comparison() {
// In the context of invalidation, :has is expensive, especially because we
// can't use caching/filtering due to now/then matches. DOM structure also
// may have changed.
return if may_return_unknown {
KleeneValue::Unknown
} else {
KleeneValue::from(!context.in_negation())
};
}
context.nest_for_relative_selector(element.opaque(), |context| {
do_match_relative_selectors(selectors, element, context, rightmost)
}).into()
}
/// Matches a relative selector in a list of relative selectors.
fn do_match_relative_selectors<E: Element>(
selectors: &[RelativeSelector<E::Impl>],
element: &E,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
) -> bool {
// Due to style sharing implications (See style sharing code), we mark the current styling context
// to mark elements considered for :has matching. Additionally, we want to mark the elements themselves,
// since we don't want to indiscriminately invalidate every element as a potential anchor.
if rightmost == SubjectOrPseudoElement::Yes {
context.considered_relative_selector.considered_anchor();
if context.needs_selector_flags() {
element.apply_selector_flags(ElementSelectorFlags::ANCHORS_RELATIVE_SELECTOR);
}
} else {
context.considered_relative_selector.considered();
if context.needs_selector_flags() {
element
.apply_selector_flags(ElementSelectorFlags::ANCHORS_RELATIVE_SELECTOR_NON_SUBJECT);
}
}
for relative_selector in selectors.iter() {
if let Some(result) = relative_selector_match_early(relative_selector, element, context) {
if result {
return true;
}
// Early return indicates no match, continue to next selector.
continue;
}
let matched = matches_relative_selector(relative_selector, element, context, rightmost);
context.selector_caches.relative_selector.add(
element.opaque(),
relative_selector,
if matched {
RelativeSelectorCachedMatch::Matched
} else {
RelativeSelectorCachedMatch::NotMatched
},
);
if matched {
return true;
}
}
false
}
fn matches_relative_selector_subtree<E: Element>(
selector: &Selector<E::Impl>,
element: &E,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
) -> bool {
let mut current = element.first_element_child();
while let Some(el) = current {
if context.needs_selector_flags() {
el.apply_selector_flags(
ElementSelectorFlags::RELATIVE_SELECTOR_SEARCH_DIRECTION_ANCESTOR,
);
}
if matches_complex_selector(selector.iter(), &el, context, rightmost).to_bool(true) {
return true;
}
if matches_relative_selector_subtree(selector, &el, context, rightmost) {
return true;
}
current = el.next_sibling_element();
}
false
}
/// Whether the :hover and :active quirk applies.
///
fn hover_and_active_quirk_applies<Impl: SelectorImpl>(
selector_iter: &SelectorIter<Impl>,
context: &MatchingContext<Impl>,
rightmost: SubjectOrPseudoElement,
) -> bool {
if context.quirks_mode() != QuirksMode::Quirks {
return false;
}
if context.is_nested() {
return false;
}
// This compound selector had a pseudo-element to the right that we
// intentionally skipped.
if rightmost == SubjectOrPseudoElement::Yes &&
context.matching_mode() == MatchingMode::ForStatelessPseudoElement
{
return false;
}
selector_iter.clone().all(|simple| match *simple {
Component::NonTSPseudoClass(ref pseudo_class) => pseudo_class.is_active_or_hover(),
_ => false,
})
}
#[derive(Clone, Copy, PartialEq)]
enum SubjectOrPseudoElement {
Yes,
No,
}
fn host_for_part<E>(element: &E, context: &MatchingContext<E::Impl>) -> Option<E>
where
E: Element,
{
let scope = context.current_host;
let mut curr = element.containing_shadow_host()?;
if scope == Some(curr.opaque()) {
return Some(curr);
}
loop {
let parent = curr.containing_shadow_host();
if parent.as_ref().map(|h| h.opaque()) == scope {
return Some(curr);
}
curr = parent?;
}
}
fn assigned_slot<E>(element: &E, context: &MatchingContext<E::Impl>) -> Option<E>
where
E: Element,
{
debug_assert!(element
.assigned_slot()
.map_or(true, |s| s.is_html_slot_element()));
let scope = context.current_host?;
let mut current_slot = element.assigned_slot()?;
while current_slot.containing_shadow_host().unwrap().opaque() != scope {
current_slot = current_slot.assigned_slot()?;
}
Some(current_slot)
}
#[inline(always)]
fn next_element_for_combinator<E>(
element: &E,
combinator: Combinator,
selector: &SelectorIter<E::Impl>,
context: &MatchingContext<E::Impl>,
) -> Option<E>
where
E: Element,
{
match combinator {
Combinator::NextSibling | Combinator::LaterSibling => element.prev_sibling_element(),
Combinator::Child | Combinator::Descendant => {
match element.parent_element() {
Some(e) => return Some(e),
None => {},
}
if !element.parent_node_is_shadow_root() {
return None;
}
//
// For the purpose of Selectors, a shadow host also appears in
// its shadow tree, with the contents of the shadow tree treated
// as its children. (In other words, the shadow host is treated as
// replacing the shadow root node.)
//
// and also:
//
// When considered within its own shadow trees, the shadow host is
// featureless. Only the :host, :host(), and :host-context()
// pseudo-classes are allowed to match it.
//
// Since we know that the parent is a shadow root, we necessarily
// are in a shadow tree of the host, and the next selector will only
// match if the selector is a featureless :host selector.
if !selector.clone().is_featureless_host_selector() {
return None;
}
element.containing_shadow_host()
},
Combinator::Part => host_for_part(element, context),
Combinator::SlotAssignment => assigned_slot(element, context),
Combinator::PseudoElement => element.pseudo_element_originating_element(),
}
}
fn matches_complex_selector_internal<E>(
mut selector_iter: SelectorIter<E::Impl>,
element: &E,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
first_subject_compound: SubjectOrPseudoElement,
) -> SelectorMatchingResult
where
E: Element,
{
debug!(
"Matching complex selector {:?} for {:?}",
selector_iter, element
);
let matches_compound_selector = {
let result = matches_compound_selector(&mut selector_iter, element, context, rightmost);
// We only care for unknown match in the first subject in compound - in the context of comparison
// invalidation, ancestors/previous sibling being an unknown match doesn't matter - we must
// invalidate to guarantee correctness.
if result == KleeneValue::Unknown && first_subject_compound == SubjectOrPseudoElement::No {
debug_assert!(
context
.matching_for_invalidation_comparison()
.unwrap_or(false),
"How did we return unknown?"
);
// Coerce the result to matched.
KleeneValue::True
} else {
result
}
};
let combinator = selector_iter.next_sequence();
if combinator.map_or(false, |c| c.is_sibling()) {
if context.needs_selector_flags() {
element.apply_selector_flags(ElementSelectorFlags::HAS_SLOW_SELECTOR_LATER_SIBLINGS);
}
}
// We don't short circuit unknown here, since the rest of the selector
// to the left of this compound may return false.
if matches_compound_selector == KleeneValue::False {
return SelectorMatchingResult::NotMatchedAndRestartFromClosestLaterSibling;
}
let combinator = match combinator {
None => {
return match matches_compound_selector {
KleeneValue::True => SelectorMatchingResult::Matched,
KleeneValue::Unknown => SelectorMatchingResult::Unknown,
KleeneValue::False => unreachable!(),
}
},
Some(c) => c,
};
let (candidate_not_found, rightmost, first_subject_compound) = match combinator {
Combinator::NextSibling | Combinator::LaterSibling => (
SelectorMatchingResult::NotMatchedAndRestartFromClosestDescendant,
SubjectOrPseudoElement::No,
SubjectOrPseudoElement::No,
),
Combinator::Child |
Combinator::Descendant |
Combinator::SlotAssignment |
Combinator::Part => (
SelectorMatchingResult::NotMatchedGlobally,
SubjectOrPseudoElement::No,
SubjectOrPseudoElement::No,
),
Combinator::PseudoElement => (
SelectorMatchingResult::NotMatchedGlobally,
rightmost,
first_subject_compound,
),
};
// Stop matching :visited as soon as we find a link, or a combinator for
// something that isn't an ancestor.
let mut visited_handling = if combinator.is_sibling() {
VisitedHandlingMode::AllLinksUnvisited
} else {
context.visited_handling()
};
let mut element = element.clone();
loop {
if element.is_link() {
visited_handling = VisitedHandlingMode::AllLinksUnvisited;
}
element = match next_element_for_combinator(&element, combinator, &selector_iter, &context)
{
None => return candidate_not_found,
Some(next_element) => next_element,
};
let result = context.with_visited_handling_mode(visited_handling, |context| {
matches_complex_selector_internal(
selector_iter.clone(),
&element,
context,
rightmost,
first_subject_compound,
)
});
match (result, combinator) {
// Return the status immediately.
(SelectorMatchingResult::Matched | SelectorMatchingResult::Unknown, _) => {
debug_assert!(
matches_compound_selector.to_bool(true),
"Compound didn't match?"
);
if result == SelectorMatchingResult::Matched &&
matches_compound_selector.to_bool(false)
{
// Matches without question
return result;
}
// Something returned unknown, so return unknown.
return SelectorMatchingResult::Unknown;
},
(SelectorMatchingResult::NotMatchedGlobally, _) | (_, Combinator::NextSibling) => {
return result;
},
// Upgrade the failure status to
// NotMatchedAndRestartFromClosestDescendant.
(_, Combinator::PseudoElement) | (_, Combinator::Child) => {
return SelectorMatchingResult::NotMatchedAndRestartFromClosestDescendant;
},
// If the failure status is
// NotMatchedAndRestartFromClosestDescendant and combinator is
// Combinator::LaterSibling, give up this Combinator::LaterSibling
// matching and restart from the closest descendant combinator.
(
SelectorMatchingResult::NotMatchedAndRestartFromClosestDescendant,
Combinator::LaterSibling,
) => {
return result;
},
// The Combinator::Descendant combinator and the status is
// NotMatchedAndRestartFromClosestLaterSibling or
// NotMatchedAndRestartFromClosestDescendant, or the
// Combinator::LaterSibling combinator and the status is
// NotMatchedAndRestartFromClosestDescendant, we can continue to
// matching on the next candidate element.
_ => {},
}
}
}
#[inline]
fn matches_local_name<E>(element: &E, local_name: &LocalName<E::Impl>) -> bool
where
E: Element,
{
let name = select_name(element, &local_name.name, &local_name.lower_name).borrow();
element.has_local_name(name)
}
fn matches_part<E>(
element: &E,
parts: &[<E::Impl as SelectorImpl>::Identifier],
context: &mut MatchingContext<E::Impl>,
) -> bool
where
E: Element,
{
let mut hosts = SmallVec::<[E; 4]>::new();
let mut host = match element.containing_shadow_host() {
Some(h) => h,
None => return false,
};
let current_host = context.current_host;
if current_host != Some(host.opaque()) {
loop {
let outer_host = host.containing_shadow_host();
if outer_host.as_ref().map(|h| h.opaque()) == current_host {
break;
}
let outer_host = match outer_host {
Some(h) => h,
None => return false,
};
// TODO(emilio): if worth it, we could early return if
// host doesn't have the exportparts attribute.
hosts.push(host);
host = outer_host;
}
}
// Translate the part into the right scope.
parts.iter().all(|part| {
let mut part = part.clone();
for host in hosts.iter().rev() {
part = match host.imported_part(&part) {
Some(p) => p,
None => return false,
};
}
element.is_part(&part)
})
}
fn matches_host<E>(
element: &E,
selector: Option<&Selector<E::Impl>>,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
) -> KleeneValue
where
E: Element,
{
let host = match context.shadow_host() {
Some(h) => h,
None => return KleeneValue::False,
};
if host != element.opaque() {
return KleeneValue::False;
}
selector.map_or(KleeneValue::True, |selector| {
context
.nest(|context| matches_complex_selector(selector.iter(), element, context, rightmost))
})
}
fn matches_slotted<E>(
element: &E,
selector: &Selector<E::Impl>,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
) -> KleeneValue
where
E: Element,
{
// <slots> are never flattened tree slottables.
if element.is_html_slot_element() {
return KleeneValue::False;
}
context.nest(|context| matches_complex_selector(selector.iter(), element, context, rightmost))
}
fn matches_rare_attribute_selector<E>(
element: &E,
attr_sel: &AttrSelectorWithOptionalNamespace<E::Impl>,
) -> bool
where
E: Element,
{
let empty_string;
let namespace = match attr_sel.namespace() {
Some(ns) => ns,
None => {
empty_string = crate::parser::namespace_empty_string::<E::Impl>();
NamespaceConstraint::Specific(&empty_string)
},
};
element.attr_matches(
&namespace,
select_name(element, &attr_sel.local_name, &attr_sel.local_name_lower),
&match attr_sel.operation {
ParsedAttrSelectorOperation::Exists => AttrSelectorOperation::Exists,
ParsedAttrSelectorOperation::WithValue {
operator,
case_sensitivity,
ref value,
} => AttrSelectorOperation::WithValue {
operator,
case_sensitivity: to_unconditional_case_sensitivity(case_sensitivity, element),
value,
},
},
)
}
/// Determines whether the given element matches the given compound selector.
#[inline]
fn matches_compound_selector<E>(
selector_iter: &mut SelectorIter<E::Impl>,
element: &E,
context: &mut MatchingContext<E::Impl>,
rightmost: SubjectOrPseudoElement,
) -> KleeneValue
where
E: Element,
{
let quirks_data = if context.quirks_mode() == QuirksMode::Quirks {
Some(selector_iter.clone())
} else {
None
};
let mut local_context = LocalMatchingContext {
shared: context,
rightmost,
quirks_data,
};
KleeneValue::any_false(
selector_iter,
|simple| matches_simple_selector(
simple,
element,
&mut local_context
)
)
}
/// Determines whether the given element matches the given single selector.
fn matches_simple_selector<E>(
selector: &Component<E::Impl>,
element: &E,
context: &mut LocalMatchingContext<E::Impl>,
) -> KleeneValue
where
E: Element,
{
debug_assert!(context.shared.is_nested() || !context.shared.in_negation());
let rightmost = context.rightmost;
KleeneValue::from(match *selector {
Component::ID(ref id) => {
element.has_id(id, context.shared.classes_and_ids_case_sensitivity())
},
Component::Class(ref class) => {
element.has_class(class, context.shared.classes_and_ids_case_sensitivity())
},
Component::LocalName(ref local_name) => matches_local_name(element, local_name),
Component::AttributeInNoNamespaceExists {
ref local_name,
ref local_name_lower,
} => element.has_attr_in_no_namespace(select_name(element, local_name, local_name_lower)),
Component::AttributeInNoNamespace {
ref local_name,
ref value,
operator,
case_sensitivity,
} => element.attr_matches(
&NamespaceConstraint::Specific(&crate::parser::namespace_empty_string::<E::Impl>()),
local_name,
&AttrSelectorOperation::WithValue {
operator,
case_sensitivity: to_unconditional_case_sensitivity(case_sensitivity, element),
value,
},
),
Component::AttributeOther(ref attr_sel) => {
matches_rare_attribute_selector(element, attr_sel)
},
Component::Part(ref parts) => matches_part(element, parts, &mut context.shared),
Component::Slotted(ref selector) => {
return matches_slotted(element, selector, &mut context.shared, rightmost);
},
Component::PseudoElement(ref pseudo) => {
element.match_pseudo_element(pseudo, context.shared)
},
Component::ExplicitUniversalType | Component::ExplicitAnyNamespace => true,
Component::Namespace(_, ref url) | Component::DefaultNamespace(ref url) => {
element.has_namespace(&url.borrow())
},
Component::ExplicitNoNamespace => {
let ns = crate::parser::namespace_empty_string::<E::Impl>();
element.has_namespace(&ns.borrow())
},
Component::NonTSPseudoClass(ref pc) => {
if let Some(ref iter) = context.quirks_data {
if pc.is_active_or_hover() &&
!element.is_link() &&
hover_and_active_quirk_applies(iter, context.shared, context.rightmost)
{
return KleeneValue::False;
}
}
element.match_non_ts_pseudo_class(pc, &mut context.shared)
},
Component::Root => element.is_root(),
Component::Empty => {
if context.shared.needs_selector_flags() {
element.apply_selector_flags(ElementSelectorFlags::HAS_EMPTY_SELECTOR);
}
element.is_empty()
},
Component::Host(ref selector) => {
return matches_host(element, selector.as_ref(), &mut context.shared, rightmost);
},
Component::ParentSelector | Component::Scope => match context.shared.scope_element {
Some(ref scope_element) => element.opaque() == *scope_element,
None => element.is_root(),
},
Component::Nth(ref nth_data) => {
return matches_generic_nth_child(element, context.shared, nth_data, &[], rightmost);
},
Component::NthOf(ref nth_of_data) => {
return context.shared.nest(|context| {
matches_generic_nth_child(
element,
context,
nth_of_data.nth_data(),
nth_of_data.selectors(),
rightmost,
)
})
},
Component::Is(ref list) | Component::Where(ref list) => {
return context.shared.nest(|context| {
matches_complex_selector_list(list.slice(), element, context, rightmost)
})
},
Component::Negation(ref list) => {
return context.shared.nest_for_negation(|context| {
!matches_complex_selector_list(list.slice(), element, context, rightmost)
})
},
Component::Has(ref relative_selectors) => {
return match_relative_selectors(
relative_selectors,
element,
context.shared,
rightmost,
);
},
Component::Combinator(_) => unsafe {
debug_unreachable!("Shouldn't try to selector-match combinators")
},
Component::RelativeSelectorAnchor => {
let anchor = context.shared.relative_selector_anchor();
// We may match inner relative selectors, in which case we want to always match.
anchor.map_or(true, |a| a == element.opaque())
},
Component::Invalid(..) => false,
})
}
#[inline(always)]
pub fn select_name<'a, E: Element, T: PartialEq>(
element: &E,
local_name: &'a T,
local_name_lower: &'a T,
) -> &'a T {
if local_name == local_name_lower || element.is_html_element_in_html_document() {
local_name_lower
} else {
local_name
}
}
#[inline(always)]
pub fn to_unconditional_case_sensitivity<'a, E: Element>(
parsed: ParsedCaseSensitivity,
element: &E,
) -> CaseSensitivity {
match parsed {
ParsedCaseSensitivity::CaseSensitive | ParsedCaseSensitivity::ExplicitCaseSensitive => {
CaseSensitivity::CaseSensitive
},
ParsedCaseSensitivity::AsciiCaseInsensitive => CaseSensitivity::AsciiCaseInsensitive,
ParsedCaseSensitivity::AsciiCaseInsensitiveIfInHtmlElementInHtmlDocument => {
if element.is_html_element_in_html_document() {
CaseSensitivity::AsciiCaseInsensitive
} else {
CaseSensitivity::CaseSensitive
}
},
}
}
fn matches_generic_nth_child<E>(
element: &E,
context: &mut MatchingContext<E::Impl>,
nth_data: &NthSelectorData,
selectors: &[Selector<E::Impl>],
rightmost: SubjectOrPseudoElement,
) -> KleeneValue
where
E: Element,
{
if element.ignores_nth_child_selectors() {
return KleeneValue::False;
}
let has_selectors = !selectors.is_empty();
let selectors_match = !has_selectors ||
matches_complex_selector_list(selectors, element, context, rightmost).to_bool(true);
if let Some(may_return_unknown) = context.matching_for_invalidation_comparison() {
// Skip expensive indexing math in invalidation.
return if selectors_match && may_return_unknown {
KleeneValue::Unknown
} else {
KleeneValue::from(selectors_match && !context.in_negation())
};
}
let NthSelectorData { ty, a, b, .. } = *nth_data;
let is_of_type = ty.is_of_type();
if ty.is_only() {
debug_assert!(
!has_selectors,
":only-child and :only-of-type cannot have a selector list!"
);
return KleeneValue::from(
matches_generic_nth_child(
element,
context,
&NthSelectorData::first(is_of_type),
selectors,
rightmost,
)
.to_bool(true) &&
matches_generic_nth_child(
element,
context,
&NthSelectorData::last(is_of_type),
selectors,
rightmost,
)
.to_bool(true),
);
}
let is_from_end = ty.is_from_end();
// It's useful to know whether this can only select the first/last element
// child for optimization purposes, see the `HAS_EDGE_CHILD_SELECTOR` flag.
let is_edge_child_selector = nth_data.is_simple_edge() && !has_selectors;
if context.needs_selector_flags() {
let mut flags = if is_edge_child_selector {
ElementSelectorFlags::HAS_EDGE_CHILD_SELECTOR
} else if is_from_end {
ElementSelectorFlags::HAS_SLOW_SELECTOR
} else {
ElementSelectorFlags::HAS_SLOW_SELECTOR_LATER_SIBLINGS
};
flags |= if has_selectors {
ElementSelectorFlags::HAS_SLOW_SELECTOR_NTH_OF
} else {
ElementSelectorFlags::HAS_SLOW_SELECTOR_NTH
};
element.apply_selector_flags(flags);
}
if !selectors_match {
return KleeneValue::False;
}
// :first/last-child are rather trivial to match, don't bother with the
// cache.
if is_edge_child_selector {
return if is_from_end {
element.next_sibling_element()
} else {
element.prev_sibling_element()
}
.is_none()
.into();
}
// Lookup or compute the index.
let index = if let Some(i) = context
.nth_index_cache(is_of_type, is_from_end, selectors)
.lookup(element.opaque())
{
i
} else {
let i = nth_child_index(
element,
context,
selectors,
is_of_type,
is_from_end,
/* check_cache = */ true,
rightmost,
);
context
.nth_index_cache(is_of_type, is_from_end, selectors)
.insert(element.opaque(), i);
i
};
debug_assert_eq!(
index,
nth_child_index(
element,
context,
selectors,
is_of_type,
is_from_end,
/* check_cache = */ false,
rightmost,
),
"invalid cache"
);
// Is there a non-negative integer n such that An+B=index?
match index.checked_sub(b) {
None => false,
Some(an) => match an.checked_div(a) {
Some(n) => n >= 0 && a * n == an,
None /* a == 0 */ => an == 0,
},
}
.into()
}
#[inline]
fn nth_child_index<E>(
element: &E,
context: &mut MatchingContext<E::Impl>,
selectors: &[Selector<E::Impl>],
is_of_type: bool,
is_from_end: bool,
check_cache: bool,
rightmost: SubjectOrPseudoElement,
) -> i32
where
E: Element,
{
// The traversal mostly processes siblings left to right. So when we walk
// siblings to the right when computing NthLast/NthLastOfType we're unlikely
// to get cache hits along the way. As such, we take the hit of walking the
// siblings to the left checking the cache in the is_from_end case (this
// matches what Gecko does). The indices-from-the-left is handled during the
// regular look further below.
if check_cache &&
is_from_end &&
!context
.nth_index_cache(is_of_type, is_from_end, selectors)
.is_empty()
{
let mut index: i32 = 1;
let mut curr = element.clone();
while let Some(e) = curr.prev_sibling_element() {
curr = e;
let matches = if is_of_type {
element.is_same_type(&curr)
} else if !selectors.is_empty() {
matches_complex_selector_list(selectors, &curr, context, rightmost).to_bool(true)
} else {
true
};
if !matches {
continue;
}
if let Some(i) = context
.nth_index_cache(is_of_type, is_from_end, selectors)
.lookup(curr.opaque())
{
return i - index;
}
index += 1;
}
}
let mut index: i32 = 1;
let mut curr = element.clone();
let next = |e: E| {
if is_from_end {
e.next_sibling_element()
} else {
e.prev_sibling_element()
}
};
while let Some(e) = next(curr) {
curr = e;
let matches = if is_of_type {
element.is_same_type(&curr)
} else if !selectors.is_empty() {
matches_complex_selector_list(selectors, &curr, context, rightmost).to_bool(true)
} else {
true
};
if !matches {
continue;
}
// If we're computing indices from the left, check each element in the
// cache. We handle the indices-from-the-right case at the top of this
// function.
if !is_from_end && check_cache {
if let Some(i) = context
.nth_index_cache(is_of_type, is_from_end, selectors)
.lookup(curr.opaque())
{
return i + index;
}
}
index += 1;
}
index
}