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9996403e73
`<media-feature>` and the upcoming `<size-feature>` from `@container`, share the same syntax and almost all of their behaviour. To avoid a lot of duplication, pull as much as possible into a FeatureQuery template class that they will both inherit from. MediaFeatureValue is renamed FeatureValue as it's also shared by both. No behaviour change.
264 lines
9.4 KiB
C++
264 lines
9.4 KiB
C++
/*
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* Copyright (c) 2021-2026, Sam Atkins <sam@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/NonnullOwnPtr.h>
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#include <AK/NonnullRefPtr.h>
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#include <AK/Optional.h>
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#include <AK/StringBuilder.h>
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#include <AK/Variant.h>
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#include <LibWeb/CSS/BooleanExpression.h>
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#include <LibWeb/CSS/Ratio.h>
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#include <LibWeb/CSS/Resolution.h>
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#include <LibWeb/CSS/StyleValues/ComputationContext.h>
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#include <LibWeb/CSS/StyleValues/KeywordStyleValue.h>
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#include <LibWeb/CSS/StyleValues/RatioStyleValue.h>
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#include <LibWeb/CSS/StyleValues/StyleValue.h>
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namespace Web::CSS {
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// https://drafts.csswg.org/mediaqueries-5/#typedef-mf-value
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class FeatureValue {
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public:
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enum class Type : u8 {
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Ident,
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Integer,
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Length,
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Ratio,
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Resolution,
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Unknown,
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};
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explicit FeatureValue(Type type, NonnullRefPtr<StyleValue const> value)
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: m_type(type)
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, m_value(move(value))
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{
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}
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String to_string(SerializationMode mode) const;
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bool is_ident() const { return m_type == Type::Ident; }
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bool is_length() const { return m_type == Type::Length; }
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bool is_integer() const { return m_type == Type::Integer; }
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bool is_ratio() const { return m_type == Type::Ratio; }
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bool is_resolution() const { return m_type == Type::Resolution; }
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bool is_unknown() const { return m_type == Type::Unknown; }
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bool is_same_type(FeatureValue const& other) const { return m_type == other.m_type; }
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Keyword ident() const
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{
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VERIFY(is_ident());
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return m_value->to_keyword();
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}
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Length length(ComputationContext const& computation_context) const
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{
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VERIFY(is_length());
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return Length::from_style_value(m_value->absolutized(computation_context), {});
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}
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Ratio ratio(ComputationContext const& computation_context) const
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{
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VERIFY(is_ratio());
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return m_value->absolutized(computation_context)->as_ratio().resolved();
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}
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Resolution resolution(ComputationContext const& computation_context) const
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{
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VERIFY(is_resolution());
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return Resolution::from_style_value(m_value->absolutized(computation_context));
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}
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i32 integer(ComputationContext const& computation_context) const
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{
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VERIFY(is_integer());
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return int_from_style_value(m_value->absolutized(computation_context));
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}
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private:
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Type m_type;
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NonnullRefPtr<StyleValue const> m_value;
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};
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enum class FeatureComparison : u8 {
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Equal,
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LessThan,
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LessThanOrEqual,
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GreaterThan,
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GreaterThanOrEqual,
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};
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StringView string_from_feature_comparison(FeatureComparison);
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bool feature_comparisons_match(FeatureComparison, FeatureComparison);
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MatchResult compare_feature_values(FeatureValue const& left, FeatureComparison comparison, FeatureValue const& right, ComputationContext const&);
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template<typename Derived, typename FeatureID>
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class FeatureQuery : public BooleanExpression {
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public:
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enum class Type : u8 {
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IsTrue,
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ExactValue,
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MinValue,
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MaxValue,
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Range,
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};
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struct Range {
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Optional<FeatureValue> left_value {};
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Optional<FeatureComparison> left_comparison {};
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Optional<FeatureComparison> right_comparison {};
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Optional<FeatureValue> right_value {};
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};
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static NonnullOwnPtr<Derived> boolean(FeatureID id)
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{
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return adopt_own(*new Derived(Type::IsTrue, id));
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}
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static NonnullOwnPtr<Derived> plain(FeatureID id, FeatureValue&& value)
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{
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return adopt_own(*new Derived(Type::ExactValue, id, move(value)));
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}
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static NonnullOwnPtr<Derived> min(FeatureID id, FeatureValue&& value)
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{
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return adopt_own(*new Derived(Type::MinValue, id, move(value)));
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}
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static NonnullOwnPtr<Derived> max(FeatureID id, FeatureValue&& value)
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{
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return adopt_own(*new Derived(Type::MaxValue, id, move(value)));
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}
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static NonnullOwnPtr<Derived> half_range(FeatureValue&& value, FeatureComparison comparison, FeatureID id)
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{
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return adopt_own(*new Derived(Type::Range, id,
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Range {
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.left_value = move(value),
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.left_comparison = comparison,
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}));
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}
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static NonnullOwnPtr<Derived> half_range(FeatureID id, FeatureComparison comparison, FeatureValue&& value)
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{
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return adopt_own(*new Derived(Type::Range, id,
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Range {
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.right_comparison = comparison,
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.right_value = move(value),
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}));
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}
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static NonnullOwnPtr<Derived> range(FeatureValue&& left_value, FeatureComparison left_comparison, FeatureID id, FeatureComparison right_comparison, FeatureValue&& right_value)
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{
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return adopt_own(*new Derived(Type::Range, id,
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Range {
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.left_value = move(left_value),
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.left_comparison = left_comparison,
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.right_comparison = right_comparison,
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.right_value = move(right_value),
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}));
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}
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Type type() const { return m_type; }
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FeatureID id() const { return m_id; }
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FeatureValue const& value() const { return m_value.template get<FeatureValue>(); }
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Range const& range() const { return m_value.template get<Range>(); }
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virtual String to_string() const override
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{
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// NB: Even though the surrounding boolean-expression grammar owns the parentheses, feature serialization
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// includes them so callers do not need a wrapper node just for serialization.
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switch (m_type) {
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case Type::IsTrue:
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return MUST(String::formatted("({})", Derived::serialize_feature_id(m_id)));
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case Type::ExactValue:
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return MUST(String::formatted("({}: {})", Derived::serialize_feature_id(m_id), value().to_string(SerializationMode::Normal)));
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case Type::MinValue:
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return MUST(String::formatted("(min-{}: {})", Derived::serialize_feature_id(m_id), value().to_string(SerializationMode::Normal)));
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case Type::MaxValue:
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return MUST(String::formatted("(max-{}: {})", Derived::serialize_feature_id(m_id), value().to_string(SerializationMode::Normal)));
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case Type::Range: {
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auto& range = this->range();
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StringBuilder builder;
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builder.append('(');
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if (range.left_comparison.has_value())
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builder.appendff("{} {} ", range.left_value->to_string(SerializationMode::Normal), string_from_feature_comparison(*range.left_comparison));
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builder.append(Derived::serialize_feature_id(m_id));
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if (range.right_comparison.has_value())
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builder.appendff(" {} {}", string_from_feature_comparison(*range.right_comparison), range.right_value->to_string(SerializationMode::Normal));
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builder.append(')');
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return builder.to_string_without_validation();
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}
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}
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VERIFY_NOT_REACHED();
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}
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protected:
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FeatureQuery(Type type, FeatureID id, Variant<Empty, FeatureValue, Range> value = {})
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: m_type(type)
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, m_id(id)
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, m_value(move(value))
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{
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}
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MatchResult evaluate_internal(FeatureValue const& queried_value, ComputationContext const& computation_context) const
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{
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switch (type()) {
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case Type::IsTrue:
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if (queried_value.is_integer())
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return as_match_result(queried_value.integer(computation_context) != 0);
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if (queried_value.is_length()) {
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auto length = queried_value.length(computation_context);
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return as_match_result(length.raw_value() != 0);
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}
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// FIXME: I couldn't figure out from the spec how ratios should be evaluated in a boolean context.
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if (queried_value.is_ratio())
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return as_match_result(!queried_value.ratio(computation_context).is_degenerate());
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if (queried_value.is_resolution())
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return as_match_result(queried_value.resolution(computation_context).to_dots_per_pixel() != 0);
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if (queried_value.is_ident()) {
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if (Derived::keyword_is_falsey(id(), queried_value.ident()))
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return MatchResult::False;
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return MatchResult::True;
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}
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return MatchResult::False;
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case Type::ExactValue:
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return compare_feature_values(value(), FeatureComparison::Equal, queried_value, computation_context);
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case Type::MinValue:
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return compare_feature_values(queried_value, FeatureComparison::GreaterThanOrEqual, value(), computation_context);
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case Type::MaxValue:
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return compare_feature_values(queried_value, FeatureComparison::LessThanOrEqual, value(), computation_context);
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case Type::Range: {
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auto const& range = this->range();
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if (range.left_comparison.has_value()) {
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if (auto const left_result = compare_feature_values(*range.left_value, *range.left_comparison, queried_value, computation_context); left_result != MatchResult::True)
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return left_result;
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}
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if (range.right_comparison.has_value()) {
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if (auto const right_result = compare_feature_values(queried_value, *range.right_comparison, *range.right_value, computation_context); right_result != MatchResult::True)
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return right_result;
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}
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return MatchResult::True;
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}
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}
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VERIFY_NOT_REACHED();
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}
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Type m_type;
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FeatureID m_id;
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Variant<Empty, FeatureValue, Range> m_value {};
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};
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}
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