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3353ec9663
The `:has()` pseudo-class requires traversing descendants (or siblings)
to find matches.
With this change we cache results keyed by `(Selector*, Element*)`
pairs. The cache is stored in `StyleComputer` and cleared at the start
of each style computation pass in `Document::update_style()`.
When `:has()` uses a descendant combinator and we find a match, we also
cache that all ancestors between the matching descendant and the
anchor match. For example with `div:has(.target)`:
```html
<div id="A"> <!-- checking :has(.target) here -->
<div id="B">
<div id="C">
<span class="target"/>
</div>
</div>
</div>
```
When we find `.target` while checking `div#A`, we also cache that
`div#B` and `div#C` match `:has(.target)` since they also contain
`.target`. Later when styling these elements, we get cache hits and skip
traversal.
53 lines
1.7 KiB
C++
53 lines
1.7 KiB
C++
/*
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* Copyright (c) 2018-2024, Andreas Kling <andreas@ladybird.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/HashMap.h>
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#include <LibWeb/CSS/Selector.h>
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#include <LibWeb/DOM/Element.h>
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namespace Web::SelectorEngine {
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enum class SelectorKind {
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Normal,
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Relative,
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};
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enum class HasMatchResult : u8 {
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Matched,
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NotMatched,
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};
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struct HasResultCacheKey {
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CSS::Selector const* selector;
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GC::Ptr<DOM::Element const> element;
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bool operator==(HasResultCacheKey const&) const = default;
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};
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struct HasResultCacheKeyTraits : Traits<HasResultCacheKey> {
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static unsigned hash(HasResultCacheKey const& key)
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{
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return pair_int_hash(ptr_hash(key.selector), ptr_hash(key.element.ptr()));
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}
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};
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using HasResultCache = HashMap<HasResultCacheKey, HasMatchResult, HasResultCacheKeyTraits>;
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struct MatchContext {
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GC::Ptr<CSS::CSSStyleSheet const> style_sheet_for_rule {};
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GC::Ptr<DOM::Element const> subject {};
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GC::Ptr<DOM::Element const> slotted_element {}; // Only set when matching a ::slotted() pseudo-element
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GC::Ptr<DOM::Element const> part_owning_parent {}; // Only set temporarily when matching a ::part() pseudo-element
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bool collect_per_element_selector_involvement_metadata { false };
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CSS::PseudoClassBitmap attempted_pseudo_class_matches {};
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HasResultCache* has_result_cache { nullptr };
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};
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bool matches(CSS::Selector const&, DOM::Element const&, GC::Ptr<DOM::Element const> shadow_host, MatchContext& context, Optional<CSS::PseudoElement> = {}, GC::Ptr<DOM::ParentNode const> scope = {}, SelectorKind selector_kind = SelectorKind::Normal, GC::Ptr<DOM::Element const> anchor = nullptr);
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}
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