Source/WebCore/css/CSSValue.h

/*
 * (C) 1999-2003 Lars Knoll (knoll@kde.org)
 * Copyright (C) 2004-2021 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 "CSSPropertyNames.h"
#include <wtf/Function.h>
#include <wtf/HashMap.h>
#include <wtf/RefCounted.h>
#include <wtf/RefPtr.h>
#include <wtf/TypeCasts.h>
#include <wtf/URLHash.h>
#include <wtf/text/ASCIILiteral.h>

namespace WebCore {

class CSSCustomPropertyValue;
class CSSStyleDeclaration;
class CachedResource;
class DeprecatedCSSOMValue;
class StyleSheetContents;

enum CSSPropertyID : uint16_t;

DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(CSSValue);
class CSSValue {
    WTF_MAKE_NONCOPYABLE(CSSValue);
    WTF_MAKE_FAST_ALLOCATED_WITH_HEAP_IDENTIFIER(CSSValue);
public:
    enum Type {
        CSS_INHERIT = 0,
        CSS_PRIMITIVE_VALUE = 1,
        CSS_VALUE_LIST = 2,
        CSS_CUSTOM = 3,
        CSS_INITIAL = 4,
        CSS_UNSET = 5,
        CSS_REVERT = 6
    };

    static constexpr unsigned refCountFlagIsStatic = 0x1;
    static constexpr unsigned refCountIncrement = 0x2; // This allows us to ref / deref without disturbing the static CSSValue flag.
    void ref() const
    {
        m_refCount += refCountIncrement;
    }
    bool hasOneRef() const { return m_refCount == refCountIncrement; }
    unsigned refCount() const { return m_refCount / refCountIncrement; }
    bool hasAtLeastOneRef() const { return m_refCount; }

    void deref()
    {
        // Customized deref() to ensure operator delete is called on
        // the appropriate subclass type.
        unsigned tempRefCount = m_refCount - refCountIncrement;
        if (!tempRefCount) {
            destroy();
            return;
        }
        m_refCount = tempRefCount;
    }

    Type cssValueType() const;
    String cssText() const;
    ASCIILiteral separatorCSSText() const;

    bool isPrimitiveValue() const { return m_classType == PrimitiveClass; }
    bool isValueList() const { return m_classType >= ValueListClass; }
    bool isValuePair() const { return m_classType == ValuePairClass; }
    
    bool isBaseValueList() const { return m_classType == ValueListClass; }
        

    bool isAspectRatioValue() const { return m_classType == AspectRatioClass; }
    bool isBorderImageSliceValue() const { return m_classType == BorderImageSliceClass; }
    bool isCanvasValue() const { return m_classType == CanvasClass; }
    bool isCrossfadeValue() const { return m_classType == CrossfadeClass; }
    bool isCursorImageValue() const { return m_classType == CursorImageClass; }
    bool isCustomPropertyValue() const { return m_classType == CustomPropertyClass; }
    bool isFunctionValue() const { return m_classType == FunctionClass; }
    bool isFontFeatureValue() const { return m_classType == FontFeatureClass; }
    bool isFontVariationValue() const { return m_classType == FontVariationClass; }
    bool isFontFaceSrcValue() const { return m_classType == FontFaceSrcClass; }
    bool isFontPaletteValuesOverrideColorsValue() const { return m_classType == FontPaletteValuesOverrideColorsClass; }
    bool isFontValue() const { return m_classType == FontClass; }
    bool isFontStyleValue() const { return m_classType == FontStyleClass; }
    bool isFontStyleRangeValue() const { return m_classType == FontStyleRangeClass; }
    bool isImageGeneratorValue() const { return m_classType >= CanvasClass && m_classType <= ConicGradientClass; }
    bool isGradientValue() const { return m_classType >= LinearGradientClass && m_classType <= ConicGradientClass; }
    bool isNamedImageValue() const { return m_classType == NamedImageClass; }
    bool isImageSetValue() const { return m_classType == ImageSetClass; }
    bool isImageValue() const { return m_classType == ImageClass; }
    bool isImplicitInitialValue() const;
    bool isInheritedValue() const { return m_classType == InheritedClass; }
    bool isInitialValue() const { return m_classType == InitialClass; }
    bool isUnsetValue() const { return m_classType == UnsetClass; }
    bool isRevertValue() const { return m_classType == RevertClass; }
    bool isGlobalKeyword() const { return isInheritedValue() || isInitialValue() || isUnsetValue() || isRevertValue(); }
    bool treatAsInitialValue(CSSPropertyID) const;
    bool treatAsInheritedValue(CSSPropertyID) const;
    bool isLinearGradientValue() const { return m_classType == LinearGradientClass; }
    bool isRadialGradientValue() const { return m_classType == RadialGradientClass; }
    bool isConicGradientValue() const { return m_classType == ConicGradientClass; }
    bool isReflectValue() const { return m_classType == ReflectClass; }
    bool isShadowValue() const { return m_classType == ShadowClass; }
    bool isCubicBezierTimingFunctionValue() const { return m_classType == CubicBezierTimingFunctionClass; }
    bool isStepsTimingFunctionValue() const { return m_classType == StepsTimingFunctionClass; }
    bool isSpringTimingFunctionValue() const { return m_classType == SpringTimingFunctionClass; }
    bool isLineBoxContainValue() const { return m_classType == LineBoxContainClass; }
    bool isCalcValue() const {return m_classType == CalculationClass; }
    bool isFilterImageValue() const { return m_classType == FilterImageClass; }
#if ENABLE(CSS_PAINTING_API)
    bool isPaintImageValue() const { return m_classType == PaintImageClass; }
#endif
    bool isContentDistributionValue() const { return m_classType == CSSContentDistributionClass; }
    bool isGridAutoRepeatValue() const { return m_classType == GridAutoRepeatClass; }
    bool isGridIntegerRepeatValue() const { return m_classType == GridIntegerRepeatClass; }
    bool isGridTemplateAreasValue() const { return m_classType == GridTemplateAreasClass; }
    bool isGridLineNamesValue() const { return m_classType == GridLineNamesClass; }
    bool isUnicodeRangeValue() const { return m_classType == UnicodeRangeClass; }

    bool isVariableReferenceValue() const { return m_classType == VariableReferenceClass; }
    bool isPendingSubstitutionValue() const { return m_classType == PendingSubstitutionValueClass; }
    
    bool hasVariableReferences() const { return isVariableReferenceValue() || isPendingSubstitutionValue(); }

    Ref<DeprecatedCSSOMValue> createDeprecatedCSSOMWrapper(CSSStyleDeclaration&) const;

    bool traverseSubresources(const WTF::Function<bool (const CachedResource&)>& handler) const;

    // What properties does this value rely on (eg, font-size for em units)
    void collectDirectComputationalDependencies(HashSet<CSSPropertyID>&) const;
    // What properties in the root element does this value rely on (eg. font-size for rem units)
    void collectDirectRootComputationalDependencies(HashSet<CSSPropertyID>&) const;

    bool equals(const CSSValue&) const;
    bool operator==(const CSSValue& other) const { return equals(other); }

protected:

    static const size_t ClassTypeBits = 6;
    enum ClassType {
        PrimitiveClass,

        // Image classes.
        ImageClass,
        CursorImageClass,

        // Image generator classes.
        CanvasClass,
#if ENABLE(CSS_PAINTING_API)
        PaintImageClass,
#endif
        NamedImageClass,
        CrossfadeClass,
        FilterImageClass,
        LinearGradientClass,
        RadialGradientClass,
        ConicGradientClass,

        // Timing function classes.
        CubicBezierTimingFunctionClass,
        StepsTimingFunctionClass,
        SpringTimingFunctionClass,

        // Other class types.
        AspectRatioClass,
        BorderImageSliceClass,
        FontFeatureClass,
        FontVariationClass,
        FontClass,
        FontStyleClass,
        FontStyleRangeClass,
        FontFaceSrcClass,
        FontPaletteValuesOverrideColorsClass,
        FunctionClass,

        InheritedClass,
        InitialClass,
        UnsetClass,
        RevertClass,

        ReflectClass,
        ShadowClass,
        UnicodeRangeClass,
        LineBoxContainClass,
        CalculationClass,
        GridTemplateAreasClass,
        ValuePairClass,

        CSSContentDistributionClass,

        CustomPropertyClass,
        VariableReferenceClass,
        PendingSubstitutionValueClass,

        // List class types must appear after ValueListClass. Note CSSFunctionValue
        // is deliberately excluded, since we don't want it exposed to the CSS OM
        // as a list.
        ValueListClass,
        ImageSetClass,
        GridLineNamesClass,
        GridAutoRepeatClass,
        GridIntegerRepeatClass,
        // Do not append non-list class types here.
    };

public:
    static const size_t ValueSeparatorBits = 2;
    enum ValueSeparator {
        SpaceSeparator,
        CommaSeparator,
        SlashSeparator
    };
    enum StaticCSSValueTag { StaticCSSValue };

protected:
    ClassType classType() const { return static_cast<ClassType>(m_classType); }

    explicit CSSValue(ClassType classType)
        : m_primitiveUnitType(0)
        , m_hasCachedCSSText(false)
        , m_valueSeparator(SpaceSeparator)
        , m_classType(classType)
    {
    }

    void makeStatic()
    {
        m_refCount |= refCountFlagIsStatic;
    }

    // NOTE: This class is non-virtual for memory and performance reasons.
    // Don't go making it virtual again unless you know exactly what you're doing!

    ~CSSValue() = default;

private:
    WEBCORE_EXPORT void destroy();

    mutable unsigned m_refCount { refCountIncrement };
protected:
    // The bits in this section are only used by specific subclasses but kept here
    // to maximize struct packing.
    // CSSPrimitiveValue bits:
    unsigned m_primitiveUnitType : 7; // CSSUnitType
    mutable unsigned m_hasCachedCSSText : 1;

    unsigned m_valueSeparator : ValueSeparatorBits;

private:
    unsigned m_classType : ClassTypeBits; // ClassType
    
friend class CSSValueList;
};

template<typename CSSValueType>
inline bool compareCSSValueVector(const Vector<Ref<CSSValueType>>& firstVector, const Vector<Ref<CSSValueType>>& secondVector)
{
    size_t size = firstVector.size();
    if (size != secondVector.size())
        return false;

    for (size_t i = 0; i < size; ++i) {
        auto& firstPtr = firstVector[i];
        auto& secondPtr = secondVector[i];
        if (firstPtr.ptr() == secondPtr.ptr() || firstPtr->equals(secondPtr))
            continue;
        return false;
    }
    return true;
}

template<typename CSSValueType>
inline bool compareCSSValuePtr(const RefPtr<CSSValueType>& first, const RefPtr<CSSValueType>& second)
{
    return first ? second && first->equals(*second) : !second;
}

template<typename CSSValueType>
inline bool compareCSSValue(const Ref<CSSValueType>& first, const Ref<CSSValueType>& second)
{
    return first.get().equals(second);
}

typedef HashMap<AtomString, RefPtr<CSSCustomPropertyValue>> CustomPropertyValueMap;

} // namespace WebCore

#define SPECIALIZE_TYPE_TRAITS_CSS_VALUE(ToValueTypeName, predicate) \
SPECIALIZE_TYPE_TRAITS_BEGIN(WebCore::ToValueTypeName) \
    static bool isType(const WebCore::CSSValue& value) { return value.predicate; } \
SPECIALIZE_TYPE_TRAITS_END()