Source/WebCore/style/RuleFeature.h

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 * Copyright (C) 2003-2011, 2014 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#pragma once

#include "CSSSelector.h"
#include "CommonAtomStrings.h"
#include <wtf/Forward.h>
#include <wtf/HashMap.h>
#include <wtf/HashSet.h>
#include <wtf/text/AtomString.h>
#include <wtf/text/AtomStringHash.h>

namespace WebCore {

class StyleRule;

namespace Style {

class RuleData;

// FIXME: Has* values should be separated so we could describe both the :has() argument and its position in the selector.
enum class MatchElement : uint8_t {
    Subject,
    Parent,
    Ancestor,
    DirectSibling,
    IndirectSibling,
    AnySibling,
    ParentSibling,
    AncestorSibling,
    HasChild,
    HasDescendant,
    HasSibling,
    HasSiblingDescendant,
    HasNonSubjectOrScopeBreaking, // FIXME: This is a catch-all for cases where :has() is in a non-subject position, or may break scope.
    Host
};
constexpr unsigned matchElementCount = static_cast<unsigned>(MatchElement::Host) + 1;

enum class IsNegation : bool { No, Yes };
enum class CanBreakScope : bool { No, Yes }; // :is/not() inside scoped selector can be affected by things outside the scope.

// For MSVC.
#pragma pack(push, 4)
struct RuleAndSelector {
    RuleAndSelector(const RuleData&);

    RefPtr<const StyleRule> styleRule;
    uint16_t selectorIndex; // Keep in sync with RuleData's selectorIndex size.
    uint16_t selectorListIndex; // Keep in sync with RuleData's selectorListIndex size.
};

struct RuleFeature : public RuleAndSelector {
    RuleFeature(const RuleData&, MatchElement, IsNegation);

    MatchElement matchElement;
    IsNegation isNegation; // Whether the selector is in a (non-paired) :not() context.
};
static_assert(sizeof(RuleFeature) <= 16, "RuleFeature is a frquently alocated object. Keep it small.");

struct RuleFeatureWithInvalidationSelector : public RuleFeature {
    RuleFeatureWithInvalidationSelector(const RuleData&, MatchElement, IsNegation, const CSSSelector* invalidationSelector);

    const CSSSelector* invalidationSelector { nullptr };
};
#pragma pack(pop)

using PseudoClassInvalidationKey = std::tuple<unsigned, uint8_t, AtomString>;

using RuleFeatureVector = Vector<RuleFeature>;

struct RuleFeatureSet {
    void add(const RuleFeatureSet&);
    void clear();
    void shrinkToFit();
    void collectFeatures(const RuleData&);
    void registerContentAttribute(const AtomString&);

    bool usesHasPseudoClass() const;
    bool usesMatchElement(MatchElement matchElement) const  { return usedMatchElements[static_cast<uint8_t>(matchElement)]; }
    void setUsesMatchElement(MatchElement matchElement) { usedMatchElements[static_cast<uint8_t>(matchElement)] = true; }

    HashSet<AtomString> idsInRules;
    HashSet<AtomString> idsMatchingAncestorsInRules;
    HashSet<AtomString> attributeCanonicalLocalNamesInRules;
    HashSet<AtomString> attributeLocalNamesInRules;
    HashSet<AtomString> contentAttributeNamesInRules;
    Vector<RuleAndSelector> siblingRules;
    Vector<RuleAndSelector> uncommonAttributeRules;

    HashMap<AtomString, std::unique_ptr<RuleFeatureVector>> idRules;
    HashMap<AtomString, std::unique_ptr<RuleFeatureVector>> classRules;
    HashMap<AtomString, std::unique_ptr<Vector<RuleFeatureWithInvalidationSelector>>> attributeRules;
    HashMap<PseudoClassInvalidationKey, std::unique_ptr<RuleFeatureVector>> pseudoClassRules;
    HashMap<PseudoClassInvalidationKey, std::unique_ptr<Vector<RuleFeatureWithInvalidationSelector>>> hasPseudoClassRules;

    HashSet<AtomString> classesAffectingHost;
    HashSet<AtomString> attributesAffectingHost;
    HashSet<CSSSelector::PseudoClassType, IntHash<CSSSelector::PseudoClassType>, WTF::StrongEnumHashTraits<CSSSelector::PseudoClassType>> pseudoClassesAffectingHost;
    HashSet<CSSSelector::PseudoClassType, IntHash<CSSSelector::PseudoClassType>, WTF::StrongEnumHashTraits<CSSSelector::PseudoClassType>> pseudoClassTypes;

    std::array<bool, matchElementCount> usedMatchElements { };

    bool usesFirstLineRules { false };
    bool usesFirstLetterRules { false };

private:
    struct SelectorFeatures {
        bool hasSiblingSelector { false };

        using InvalidationFeature = std::tuple<const CSSSelector*, MatchElement, IsNegation>;

        Vector<InvalidationFeature> ids;
        Vector<InvalidationFeature> classes;
        Vector<InvalidationFeature> attributes;
        Vector<InvalidationFeature> pseudoClasses;
        Vector<InvalidationFeature> hasPseudoClasses;
    };
    void recursivelyCollectFeaturesFromSelector(SelectorFeatures&, const CSSSelector&, MatchElement = MatchElement::Subject, IsNegation = IsNegation::No, CanBreakScope = CanBreakScope::No);
};

bool isHasPseudoClassMatchElement(MatchElement);
MatchElement computeHasPseudoClassMatchElement(const CSSSelector&);

enum class InvalidationKeyType : uint8_t { Universal = 1, Class, Id, Tag };
PseudoClassInvalidationKey makePseudoClassInvalidationKey(CSSSelector::PseudoClassType, InvalidationKeyType, const AtomString& = starAtom());

inline bool isUniversalInvalidation(const PseudoClassInvalidationKey& key)
{
    return static_cast<InvalidationKeyType>(std::get<1>(key)) == InvalidationKeyType::Universal;
}

inline bool RuleFeatureSet::usesHasPseudoClass() const
{
    return usesMatchElement(MatchElement::HasChild)
        || usesMatchElement(MatchElement::HasDescendant)
        || usesMatchElement(MatchElement::HasSiblingDescendant)
        || usesMatchElement(MatchElement::HasSibling)
        || usesMatchElement(MatchElement::HasNonSubjectOrScopeBreaking);
}

} // namespace Style
} // namespace WebCore