mirror of
https://github.com/RGBCube/serenity
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388 lines
18 KiB
C++
388 lines
18 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include "Selector.h"
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#include <LibWeb/CSS/Serialize.h>
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namespace Web::CSS {
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Selector::Selector(Vector<CompoundSelector>&& compound_selectors)
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: m_compound_selectors(move(compound_selectors))
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{
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// FIXME: This assumes that only one pseudo-element is allowed in a selector, and that it appears at the end.
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// This is not true in Selectors-4!
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if (!m_compound_selectors.is_empty()) {
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for (auto const& simple_selector : m_compound_selectors.last().simple_selectors) {
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if (simple_selector.type == SimpleSelector::Type::PseudoElement) {
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m_pseudo_element = simple_selector.pseudo_element();
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break;
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}
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}
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}
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}
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// https://www.w3.org/TR/selectors-4/#specificity-rules
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u32 Selector::specificity() const
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{
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if (m_specificity.has_value())
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return *m_specificity;
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constexpr u32 ids_shift = 16;
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constexpr u32 classes_shift = 8;
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constexpr u32 tag_names_shift = 0;
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constexpr u32 ids_mask = 0xff << ids_shift;
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constexpr u32 classes_mask = 0xff << classes_shift;
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constexpr u32 tag_names_mask = 0xff << tag_names_shift;
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u32 ids = 0;
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u32 classes = 0;
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u32 tag_names = 0;
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auto count_specificity_of_most_complex_selector = [&](auto& selector_list) {
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u32 max_selector_list_argument_specificity = 0;
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for (auto const& complex_selector : selector_list) {
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max_selector_list_argument_specificity = max(max_selector_list_argument_specificity, complex_selector->specificity());
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}
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u32 child_ids = (max_selector_list_argument_specificity & ids_mask) >> ids_shift;
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u32 child_classes = (max_selector_list_argument_specificity & classes_mask) >> classes_shift;
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u32 child_tag_names = (max_selector_list_argument_specificity & tag_names_mask) >> tag_names_shift;
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ids += child_ids;
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classes += child_classes;
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tag_names += child_tag_names;
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};
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for (auto& list : m_compound_selectors) {
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for (auto& simple_selector : list.simple_selectors) {
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switch (simple_selector.type) {
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case SimpleSelector::Type::Id:
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// count the number of ID selectors in the selector (= A)
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++ids;
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break;
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case SimpleSelector::Type::Class:
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case SimpleSelector::Type::Attribute:
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// count the number of class selectors, attributes selectors, and pseudo-classes in the selector (= B)
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++classes;
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break;
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case SimpleSelector::Type::PseudoClass: {
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auto& pseudo_class = simple_selector.pseudo_class();
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switch (pseudo_class.type) {
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case PseudoClass::Is:
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case PseudoClass::Not: {
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// The specificity of an :is(), :not(), or :has() pseudo-class is replaced by the
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// specificity of the most specific complex selector in its selector list argument.
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count_specificity_of_most_complex_selector(pseudo_class.argument_selector_list);
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break;
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}
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case PseudoClass::NthChild:
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case PseudoClass::NthLastChild: {
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// Analogously, the specificity of an :nth-child() or :nth-last-child() selector
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// is the specificity of the pseudo class itself (counting as one pseudo-class selector)
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// plus the specificity of the most specific complex selector in its selector list argument (if any).
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++classes;
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count_specificity_of_most_complex_selector(pseudo_class.argument_selector_list);
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break;
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}
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case PseudoClass::Where:
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// The specificity of a :where() pseudo-class is replaced by zero.
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break;
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default:
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++classes;
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break;
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}
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break;
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}
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case SimpleSelector::Type::TagName:
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case SimpleSelector::Type::PseudoElement:
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// count the number of type selectors and pseudo-elements in the selector (= C)
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++tag_names;
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break;
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case SimpleSelector::Type::Universal:
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// ignore the universal selector
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break;
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}
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}
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}
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// Due to storage limitations, implementations may have limitations on the size of A, B, or C.
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// If so, values higher than the limit must be clamped to that limit, and not overflow.
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m_specificity = (min(ids, 0xff) << ids_shift)
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+ (min(classes, 0xff) << classes_shift)
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+ (min(tag_names, 0xff) << tag_names_shift);
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return *m_specificity;
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}
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// https://www.w3.org/TR/cssom/#serialize-a-simple-selector
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String Selector::SimpleSelector::serialize() const
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{
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StringBuilder s;
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switch (type) {
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case Selector::SimpleSelector::Type::TagName:
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case Selector::SimpleSelector::Type::Universal: {
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auto qualified_name = this->qualified_name();
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// 1. If the namespace prefix maps to a namespace that is not the default namespace and is not the null
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// namespace (not in a namespace) append the serialization of the namespace prefix as an identifier,
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// followed by a "|" (U+007C) to s.
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if (qualified_name.namespace_type == QualifiedName::NamespaceType::Named) {
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serialize_an_identifier(s, qualified_name.namespace_);
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s.append('|');
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}
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// 2. If the namespace prefix maps to a namespace that is the null namespace (not in a namespace)
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// append "|" (U+007C) to s.
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if (qualified_name.namespace_type == QualifiedName::NamespaceType::None)
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s.append('|');
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// 3. If this is a type selector append the serialization of the element name as an identifier to s.
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if (type == Selector::SimpleSelector::Type::TagName)
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serialize_an_identifier(s, qualified_name.name.name);
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// 4. If this is a universal selector append "*" (U+002A) to s.
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if (type == Selector::SimpleSelector::Type::Universal)
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s.append('*');
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break;
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}
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case Selector::SimpleSelector::Type::Attribute: {
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auto& attribute = this->attribute();
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// 1. Append "[" (U+005B) to s.
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s.append('[');
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// 2. If the namespace prefix maps to a namespace that is not the null namespace (not in a namespace)
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// append the serialization of the namespace prefix as an identifier, followed by a "|" (U+007C) to s.
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if (attribute.qualified_name.namespace_type == QualifiedName::NamespaceType::Named) {
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serialize_an_identifier(s, attribute.qualified_name.namespace_);
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s.append('|');
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}
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// 3. Append the serialization of the attribute name as an identifier to s.
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serialize_an_identifier(s, attribute.qualified_name.name.name);
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// 4. If there is an attribute value specified, append "=", "~=", "|=", "^=", "$=", or "*=" as appropriate (depending on the type of attribute selector),
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// followed by the serialization of the attribute value as a string, to s.
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if (!attribute.value.is_empty()) {
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switch (attribute.match_type) {
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case Selector::SimpleSelector::Attribute::MatchType::ExactValueMatch:
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s.append("="sv);
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break;
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case Selector::SimpleSelector::Attribute::MatchType::ContainsWord:
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s.append("~="sv);
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break;
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case Selector::SimpleSelector::Attribute::MatchType::ContainsString:
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s.append("*="sv);
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break;
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case Selector::SimpleSelector::Attribute::MatchType::StartsWithSegment:
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s.append("|="sv);
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break;
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case Selector::SimpleSelector::Attribute::MatchType::StartsWithString:
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s.append("^="sv);
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break;
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case Selector::SimpleSelector::Attribute::MatchType::EndsWithString:
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s.append("$="sv);
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break;
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default:
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break;
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}
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serialize_a_string(s, attribute.value);
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}
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// 5. If the attribute selector has the case-insensitivity flag present, append " i" (U+0020 U+0069) to s.
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// If the attribute selector has the case-insensitivity flag present, append " s" (U+0020 U+0073) to s.
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// (the line just above is an addition to CSS OM to match Selectors Level 4 last draft)
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switch (attribute.case_type) {
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case Selector::SimpleSelector::Attribute::CaseType::CaseInsensitiveMatch:
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s.append(" i"sv);
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break;
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case Selector::SimpleSelector::Attribute::CaseType::CaseSensitiveMatch:
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s.append(" s"sv);
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break;
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default:
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break;
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}
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// 6. Append "]" (U+005D) to s.
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s.append(']');
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break;
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}
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case Selector::SimpleSelector::Type::Class:
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// Append a "." (U+002E), followed by the serialization of the class name as an identifier to s.
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s.append('.');
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serialize_an_identifier(s, name());
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break;
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case Selector::SimpleSelector::Type::Id:
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// Append a "#" (U+0023), followed by the serialization of the ID as an identifier to s.
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s.append('#');
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serialize_an_identifier(s, name());
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break;
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case Selector::SimpleSelector::Type::PseudoClass: {
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auto& pseudo_class = this->pseudo_class();
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auto metadata = pseudo_class_metadata(pseudo_class.type);
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// HACK: `:host()` has both a function and a non-function form, so handle that first.
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// It's also not in the spec.
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if (pseudo_class.type == PseudoClass::Host) {
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if (pseudo_class.argument_selector_list.is_empty()) {
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s.append(':');
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s.append(pseudo_class_name(pseudo_class.type));
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} else {
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s.append(':');
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s.append(pseudo_class_name(pseudo_class.type));
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s.append('(');
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s.append(serialize_a_group_of_selectors(pseudo_class.argument_selector_list));
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s.append(')');
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}
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}
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// If the pseudo-class does not accept arguments append ":" (U+003A), followed by the name of the pseudo-class, to s.
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else if (metadata.is_valid_as_identifier) {
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s.append(':');
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s.append(pseudo_class_name(pseudo_class.type));
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}
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// Otherwise, append ":" (U+003A), followed by the name of the pseudo-class, followed by "(" (U+0028),
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// followed by the value of the pseudo-class argument(s) determined as per below, followed by ")" (U+0029), to s.
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else {
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s.append(':');
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s.append(pseudo_class_name(pseudo_class.type));
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s.append('(');
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if (pseudo_class.type == PseudoClass::NthChild
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|| pseudo_class.type == PseudoClass::NthLastChild
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|| pseudo_class.type == PseudoClass::NthOfType
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|| pseudo_class.type == PseudoClass::NthLastOfType) {
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// The result of serializing the value using the rules to serialize an <an+b> value.
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s.append(pseudo_class.nth_child_pattern.serialize());
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} else if (pseudo_class.type == PseudoClass::Not
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|| pseudo_class.type == PseudoClass::Is
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|| pseudo_class.type == PseudoClass::Where) {
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// The result of serializing the value using the rules for serializing a group of selectors.
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// NOTE: `:is()` and `:where()` aren't in the spec for this yet, but it should be!
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s.append(serialize_a_group_of_selectors(pseudo_class.argument_selector_list));
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} else if (pseudo_class.type == PseudoClass::Lang) {
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// The serialization of a comma-separated list of each argument’s serialization as a string, preserving relative order.
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s.join(", "sv, pseudo_class.languages);
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}
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s.append(')');
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}
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break;
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}
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case Selector::SimpleSelector::Type::PseudoElement:
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// Note: Pseudo-elements are dealt with in Selector::serialize()
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break;
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default:
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dbgln("FIXME: Unsupported simple selector serialization for type {}", to_underlying(type));
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break;
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}
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return MUST(s.to_string());
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}
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// https://www.w3.org/TR/cssom/#serialize-a-selector
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String Selector::serialize() const
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{
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StringBuilder s;
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// To serialize a selector let s be the empty string, run the steps below for each part of the chain of the selector, and finally return s:
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for (size_t i = 0; i < compound_selectors().size(); ++i) {
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auto const& compound_selector = compound_selectors()[i];
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// 1. If there is only one simple selector in the compound selectors which is a universal selector, append the result of serializing the universal selector to s.
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if (compound_selector.simple_selectors.size() == 1
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&& compound_selector.simple_selectors.first().type == Selector::SimpleSelector::Type::Universal) {
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s.append(compound_selector.simple_selectors.first().serialize());
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}
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// 2. Otherwise, for each simple selector in the compound selectors that is not a universal selector
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// of which the namespace prefix maps to a namespace that is not the default namespace
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// serialize the simple selector and append the result to s.
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else {
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for (auto& simple_selector : compound_selector.simple_selectors) {
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if (simple_selector.type == SimpleSelector::Type::Universal) {
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auto qualified_name = simple_selector.qualified_name();
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if (qualified_name.namespace_type == SimpleSelector::QualifiedName::NamespaceType::Default)
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continue;
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// FIXME: I *think* if we have a namespace prefix that happens to equal the same as the default namespace,
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// we also should skip it. But we don't have access to that here. eg:
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// <style>
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// @namespace "http://example";
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// @namespace foo "http://example";
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// foo|*.bar { } /* This would skip the `foo|*` when serializing. */
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// </style>
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}
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s.append(simple_selector.serialize());
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}
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}
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// 3. If this is not the last part of the chain of the selector append a single SPACE (U+0020),
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// followed by the combinator ">", "+", "~", ">>", "||", as appropriate, followed by another
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// single SPACE (U+0020) if the combinator was not whitespace, to s.
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if (i != compound_selectors().size() - 1) {
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s.append(' ');
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// Note: The combinator that appears between parts `i` and `i+1` appears with the `i+1` selector,
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// so we have to check that one.
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switch (compound_selectors()[i + 1].combinator) {
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case Selector::Combinator::ImmediateChild:
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s.append("> "sv);
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break;
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case Selector::Combinator::NextSibling:
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s.append("+ "sv);
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break;
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case Selector::Combinator::SubsequentSibling:
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s.append("~ "sv);
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break;
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case Selector::Combinator::Column:
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s.append("|| "sv);
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break;
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default:
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break;
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}
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} else {
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// 4. If this is the last part of the chain of the selector and there is a pseudo-element,
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// append "::" followed by the name of the pseudo-element, to s.
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if (compound_selector.simple_selectors.last().type == Selector::SimpleSelector::Type::PseudoElement) {
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s.append("::"sv);
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s.append(pseudo_element_name(compound_selector.simple_selectors.last().pseudo_element()));
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}
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}
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}
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return MUST(s.to_string());
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}
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// https://www.w3.org/TR/cssom/#serialize-a-group-of-selectors
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String serialize_a_group_of_selectors(Vector<NonnullRefPtr<Selector>> const& selectors)
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{
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// To serialize a group of selectors serialize each selector in the group of selectors and then serialize a comma-separated list of these serializations.
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return MUST(String::join(", "sv, selectors));
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}
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Optional<Selector::PseudoElement> pseudo_element_from_string(StringView name)
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{
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if (name.equals_ignoring_ascii_case("after"sv)) {
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return Selector::PseudoElement::After;
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} else if (name.equals_ignoring_ascii_case("before"sv)) {
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return Selector::PseudoElement::Before;
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} else if (name.equals_ignoring_ascii_case("first-letter"sv)) {
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return Selector::PseudoElement::FirstLetter;
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} else if (name.equals_ignoring_ascii_case("first-line"sv)) {
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return Selector::PseudoElement::FirstLine;
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} else if (name.equals_ignoring_ascii_case("marker"sv)) {
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return Selector::PseudoElement::Marker;
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} else if (name.equals_ignoring_ascii_case("-webkit-progress-bar"sv)) {
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return Selector::PseudoElement::ProgressBar;
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} else if (name.equals_ignoring_ascii_case("-webkit-progress-value"sv)) {
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return Selector::PseudoElement::ProgressValue;
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} else if (name.equals_ignoring_ascii_case("placeholder"sv)) {
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return Selector::PseudoElement::Placeholder;
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} else if (name.equals_ignoring_ascii_case("selection"sv)) {
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return Selector::PseudoElement::Selection;
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}
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return {};
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}
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}
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