/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021-2022, Sam Atkins <atkinssj@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "Selector.h"
#include <LibWeb/CSS/Serialize.h>
namespace Web::CSS {
Selector::Selector(Vector<CompoundSelector>&& compound_selectors)
: m_compound_selectors(move(compound_selectors))
{
// FIXME: This assumes that only one pseudo-element is allowed in a selector, and that it appears at the end.
// This is not true in Selectors-4!
if (!m_compound_selectors.is_empty()) {
for (auto const& simple_selector : m_compound_selectors.last().simple_selectors) {
if (simple_selector.type == SimpleSelector::Type::PseudoElement) {
m_pseudo_element = simple_selector.pseudo_element();
break;
}
}
}
}
// https://www.w3.org/TR/selectors-4/#specificity-rules
u32 Selector::specificity() const
{
if (m_specificity.has_value())
return *m_specificity;
constexpr u32 ids_shift = 16;
constexpr u32 classes_shift = 8;
constexpr u32 tag_names_shift = 0;
constexpr u32 ids_mask = 0xff << ids_shift;
constexpr u32 classes_mask = 0xff << classes_shift;
constexpr u32 tag_names_mask = 0xff << tag_names_shift;
u32 ids = 0;
u32 classes = 0;
u32 tag_names = 0;
auto count_specificity_of_most_complex_selector = [&](auto& selector_list) {
u32 max_selector_list_argument_specificity = 0;
for (auto const& complex_selector : selector_list) {
max_selector_list_argument_specificity = max(max_selector_list_argument_specificity, complex_selector.specificity());
}
u32 child_ids = (max_selector_list_argument_specificity & ids_mask) >> ids_shift;
u32 child_classes = (max_selector_list_argument_specificity & classes_mask) >> classes_shift;
u32 child_tag_names = (max_selector_list_argument_specificity & tag_names_mask) >> tag_names_shift;
ids += child_ids;
classes += child_classes;
tag_names += child_tag_names;
};
for (auto& list : m_compound_selectors) {
for (auto& simple_selector : list.simple_selectors) {
switch (simple_selector.type) {
case SimpleSelector::Type::Id:
// count the number of ID selectors in the selector (= A)
++ids;
break;
case SimpleSelector::Type::Class:
case SimpleSelector::Type::Attribute:
// count the number of class selectors, attributes selectors, and pseudo-classes in the selector (= B)
++classes;
break;
case SimpleSelector::Type::PseudoClass: {
auto& pseudo_class = simple_selector.pseudo_class();
switch (pseudo_class.type) {
case SimpleSelector::PseudoClass::Type::Is:
case SimpleSelector::PseudoClass::Type::Not: {
// The specificity of an :is(), :not(), or :has() pseudo-class is replaced by the
// specificity of the most specific complex selector in its selector list argument.
count_specificity_of_most_complex_selector(pseudo_class.argument_selector_list);
break;
}
case SimpleSelector::PseudoClass::Type::NthChild:
case SimpleSelector::PseudoClass::Type::NthLastChild: {
// Analogously, the specificity of an :nth-child() or :nth-last-child() selector
// is the specificity of the pseudo class itself (counting as one pseudo-class selector)
// plus the specificity of the most specific complex selector in its selector list argument (if any).
++classes;
count_specificity_of_most_complex_selector(pseudo_class.argument_selector_list);
break;
}
case SimpleSelector::PseudoClass::Type::Where:
// The specificity of a :where() pseudo-class is replaced by zero.
break;
default:
++classes;
break;
}
break;
}
case SimpleSelector::Type::TagName:
case SimpleSelector::Type::PseudoElement:
// count the number of type selectors and pseudo-elements in the selector (= C)
++tag_names;
break;
case SimpleSelector::Type::Universal:
// ignore the universal selector
break;
}
}
}
// Due to storage limitations, implementations may have limitations on the size of A, B, or C.
// If so, values higher than the limit must be clamped to that limit, and not overflow.
m_specificity = (min(ids, 0xff) << ids_shift)
+ (min(classes, 0xff) << classes_shift)
+ (min(tag_names, 0xff) << tag_names_shift);
return *m_specificity;
}
// https://www.w3.org/TR/cssom/#serialize-a-simple-selector
String Selector::SimpleSelector::serialize() const
{
StringBuilder s;
switch (type) {
case Selector::SimpleSelector::Type::TagName:
case Selector::SimpleSelector::Type::Universal:
// FIXME: 1. If the namespace prefix maps to a namespace that is not the default namespace and is not the null namespace (not in a namespace) append the serialization of the namespace prefix as an identifier, followed by a "|" (U+007C) to s.
// FIXME: 2. If the namespace prefix maps to a namespace that is the null namespace (not in a namespace) append "|" (U+007C) to s.
// 3. If this is a type selector append the serialization of the element name as an identifier to s.
if (type == Selector::SimpleSelector::Type::TagName) {
serialize_an_identifier(s, name());
}
// 4. If this is a universal selector append "*" (U+002A) to s.
if (type == Selector::SimpleSelector::Type::Universal)
s.append('*');
break;
case Selector::SimpleSelector::Type::Attribute: {
auto& attribute = this->attribute();
// 1. Append "[" (U+005B) to s.
s.append('[');
// FIXME: 2. If the namespace prefix maps to a namespace that is not the null namespace (not in a namespace) append the serialization of the namespace prefix as an identifier, followed by a "|" (U+007C) to s.
// 3. Append the serialization of the attribute name as an identifier to s.
serialize_an_identifier(s, attribute.name);
// 4. If there is an attribute value specified, append "=", "~=", "|=", "^=", "$=", or "*=" as appropriate (depending on the type of attribute selector),
// followed by the serialization of the attribute value as a string, to s.
if (!attribute.value.is_null()) {
switch (attribute.match_type) {
case Selector::SimpleSelector::Attribute::MatchType::ExactValueMatch:
s.append("="sv);
break;
case Selector::SimpleSelector::Attribute::MatchType::ContainsWord:
s.append("~="sv);
break;
case Selector::SimpleSelector::Attribute::MatchType::ContainsString:
s.append("*="sv);
break;
case Selector::SimpleSelector::Attribute::MatchType::StartsWithSegment:
s.append("|="sv);
break;
case Selector::SimpleSelector::Attribute::MatchType::StartsWithString:
s.append("^="sv);
break;
case Selector::SimpleSelector::Attribute::MatchType::EndsWithString:
s.append("$="sv);
break;
default:
break;
}
serialize_a_string(s, attribute.value);
}
// 5. If the attribute selector has the case-insensitivity flag present, append " i" (U+0020 U+0069) to s.
// If the attribute selector has the case-insensitivity flag present, append " s" (U+0020 U+0073) to s.
// (the line just above is an addition to CSS OM to match Selectors Level 4 last draft)
switch (attribute.case_type) {
case Selector::SimpleSelector::Attribute::CaseType::CaseInsensitiveMatch:
s.append(" i"sv);
break;
case Selector::SimpleSelector::Attribute::CaseType::CaseSensitiveMatch:
s.append(" s"sv);
break;
default:
break;
}
// 6. Append "]" (U+005D) to s.
s.append(']');
break;
}
case Selector::SimpleSelector::Type::Class:
// Append a "." (U+002E), followed by the serialization of the class name as an identifier to s.
s.append('.');
serialize_an_identifier(s, name());
break;
case Selector::SimpleSelector::Type::Id:
// Append a "#" (U+0023), followed by the serialization of the ID as an identifier to s.
s.append('#');
serialize_an_identifier(s, name());
break;
case Selector::SimpleSelector::Type::PseudoClass: {
auto& pseudo_class = this->pseudo_class();
switch (pseudo_class.type) {
case Selector::SimpleSelector::PseudoClass::Type::Link:
case Selector::SimpleSelector::PseudoClass::Type::Visited:
case Selector::SimpleSelector::PseudoClass::Type::Hover:
case Selector::SimpleSelector::PseudoClass::Type::Focus:
case Selector::SimpleSelector::PseudoClass::Type::FocusWithin:
case Selector::SimpleSelector::PseudoClass::Type::FirstChild:
case Selector::SimpleSelector::PseudoClass::Type::LastChild:
case Selector::SimpleSelector::PseudoClass::Type::OnlyChild:
case Selector::SimpleSelector::PseudoClass::Type::Empty:
case Selector::SimpleSelector::PseudoClass::Type::Root:
case Selector::SimpleSelector::PseudoClass::Type::FirstOfType:
case Selector::SimpleSelector::PseudoClass::Type::LastOfType:
case Selector::SimpleSelector::PseudoClass::Type::OnlyOfType:
case Selector::SimpleSelector::PseudoClass::Type::Disabled:
case Selector::SimpleSelector::PseudoClass::Type::Enabled:
case Selector::SimpleSelector::PseudoClass::Type::Checked:
case Selector::SimpleSelector::PseudoClass::Type::Active:
// If the pseudo-class does not accept arguments append ":" (U+003A), followed by the name of the pseudo-class, to s.
s.append(':');
s.append(pseudo_class_name(pseudo_class.type));
break;
case Selector::SimpleSelector::PseudoClass::Type::NthChild:
case Selector::SimpleSelector::PseudoClass::Type::NthLastChild:
case Selector::SimpleSelector::PseudoClass::Type::NthOfType:
case Selector::SimpleSelector::PseudoClass::Type::NthLastOfType:
case Selector::SimpleSelector::PseudoClass::Type::Not:
case Selector::SimpleSelector::PseudoClass::Type::Is:
case Selector::SimpleSelector::PseudoClass::Type::Where:
// Otherwise, append ":" (U+003A), followed by the name of the pseudo-class, followed by "(" (U+0028),
// followed by the value of the pseudo-class argument(s) determined as per below, followed by ")" (U+0029), to s.
s.append(':');
s.append(pseudo_class_name(pseudo_class.type));
s.append('(');
if (pseudo_class.type == Selector::SimpleSelector::PseudoClass::Type::NthChild
|| pseudo_class.type == Selector::SimpleSelector::PseudoClass::Type::NthLastChild
|| pseudo_class.type == Selector::SimpleSelector::PseudoClass::Type::NthOfType
|| pseudo_class.type == Selector::SimpleSelector::PseudoClass::Type::NthLastOfType) {
// The result of serializing the value using the rules to serialize an <an+b> value.
s.append(pseudo_class.nth_child_pattern.serialize());
} else if (pseudo_class.type == Selector::SimpleSelector::PseudoClass::Type::Not
|| pseudo_class.type == Selector::SimpleSelector::PseudoClass::Type::Is
|| pseudo_class.type == Selector::SimpleSelector::PseudoClass::Type::Where) {
// The result of serializing the value using the rules for serializing a group of selectors.
// NOTE: `:is()` and `:where()` aren't in the spec for this yet, but it should be!
s.append(serialize_a_group_of_selectors(pseudo_class.argument_selector_list));
}
s.append(')');
break;
default:
VERIFY_NOT_REACHED();
}
break;
}
case Selector::SimpleSelector::Type::PseudoElement:
// Note: Pseudo-elements are dealt with in Selector::serialize()
break;
default:
dbgln("FIXME: Unsupported simple selector serialization for type {}", to_underlying(type));
break;
}
return s.to_string();
}
// https://www.w3.org/TR/cssom/#serialize-a-selector
String Selector::serialize() const
{
StringBuilder s;
// 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:
for (size_t i = 0; i < compound_selectors().size(); ++i) {
auto const& compound_selector = compound_selectors()[i];
// 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.
if (compound_selector.simple_selectors.size() == 1
&& compound_selector.simple_selectors.first().type == Selector::SimpleSelector::Type::Universal) {
s.append(compound_selector.simple_selectors.first().serialize());
}
// 2. Otherwise, for each simple selector in the compound selectors...
// FIXME: ...that is not a universal selector of which the namespace prefix maps to a namespace that is not the default namespace...
// ...serialize the simple selector and append the result to s.
else {
for (auto& simple_selector : compound_selector.simple_selectors) {
s.append(simple_selector.serialize());
}
}
// 3. If this is not the last part of the chain of the selector append a single SPACE (U+0020),
// followed by the combinator ">", "+", "~", ">>", "||", as appropriate, followed by another
// single SPACE (U+0020) if the combinator was not whitespace, to s.
if (i != compound_selectors().size() - 1) {
s.append(' ');
// Note: The combinator that appears between parts `i` and `i+1` appears with the `i+1` selector,
// so we have to check that one.
switch (compound_selectors()[i + 1].combinator) {
case Selector::Combinator::ImmediateChild:
s.append("> "sv);
break;
case Selector::Combinator::NextSibling:
s.append("+ "sv);
break;
case Selector::Combinator::SubsequentSibling:
s.append("~ "sv);
break;
case Selector::Combinator::Column:
s.append("|| "sv);
break;
default:
break;
}
} else {
// 4. If this is the last part of the chain of the selector and there is a pseudo-element,
// append "::" followed by the name of the pseudo-element, to s.
if (compound_selector.simple_selectors.last().type == Selector::SimpleSelector::Type::PseudoElement) {
s.append("::"sv);
s.append(pseudo_element_name(compound_selector.simple_selectors.last().pseudo_element()));
}
}
}
return s.to_string();
}
// https://www.w3.org/TR/cssom/#serialize-a-group-of-selectors
String serialize_a_group_of_selectors(NonnullRefPtrVector<Selector> const& selectors)
{
// To serialize a group of selectors serialize each selector in the group of selectors and then serialize a comma-separated list of these serializations.
StringBuilder builder;
builder.join(", "sv, selectors);
return builder.to_string();
}
Optional<Selector::PseudoElement> pseudo_element_from_string(StringView name)
{
if (name.equals_ignoring_case("after"sv)) {
return Selector::PseudoElement::After;
} else if (name.equals_ignoring_case("before"sv)) {
return Selector::PseudoElement::Before;
} else if (name.equals_ignoring_case("first-letter"sv)) {
return Selector::PseudoElement::FirstLetter;
} else if (name.equals_ignoring_case("first-line"sv)) {
return Selector::PseudoElement::FirstLine;
} else if (name.equals_ignoring_case("marker"sv)) {
return Selector::PseudoElement::Marker;
} else if (name.equals_ignoring_case("-webkit-progress-bar"sv)) {
return Selector::PseudoElement::ProgressBar;
} else if (name.equals_ignoring_case("-webkit-progress-value"sv)) {
return Selector::PseudoElement::ProgressValue;
}
return {};
}
}