Source/WebCore/css/DOMCSSRegisterCustomProperty.cpp

/*
 * Copyright (C) 2018 Apple Inc. All rights reserved.
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#include "config.h"
#include "DOMCSSRegisterCustomProperty.h"

#include "CSSCustomPropertyValue.h"
#include "CSSPropertyNames.h"
#include "CSSPropertyParser.h"
#include "CSSRegisteredCustomProperty.h"
#include "CSSTokenizer.h"
#include "DOMCSSNamespace.h"
#include "Document.h"
#include "StyleBuilderConverter.h"
#include <wtf/text/WTFString.h>

namespace WebCore {

ExceptionOr<void> DOMCSSRegisterCustomProperty::registerProperty(Document& document, const DOMCSSCustomPropertyDescriptor& descriptor)
{
    if (!isCustomPropertyName(descriptor.name))
        return Exception { SyntaxError, "The name of this property is not a custom property name." };

    RefPtr<CSSCustomPropertyValue> initialValue;
    if (!descriptor.initialValue.isEmpty()) {
        CSSTokenizer tokenizer(descriptor.initialValue);
        StyleResolver styleResolver(document);

        // We need to initialize this so that we can successfully parse computationally dependent values (like em units).
        // We don't actually need the values to be accurate, since they will be rejected later anyway
        styleResolver.applyPropertyToStyle(CSSPropertyInvalid, nullptr, styleResolver.defaultStyleForElement());
        styleResolver.updateFont();

        HashSet<CSSPropertyID> dependencies;
        CSSPropertyParser::collectParsedCustomPropertyValueDependencies(descriptor.syntax, false, dependencies, tokenizer.tokenRange(), strictCSSParserContext());

        if (!dependencies.isEmpty())
            return Exception { SyntaxError, "The given initial value must be computationally independent." };

        initialValue = CSSPropertyParser::parseTypedCustomPropertyValue(descriptor.name, descriptor.syntax, tokenizer.tokenRange(), styleResolver, strictCSSParserContext());

        if (!initialValue || !initialValue->isResolved())
            return Exception { SyntaxError, "The given initial value does not parse for the given syntax." };

        initialValue->collectDirectComputationalDependencies(dependencies);
        initialValue->collectDirectRootComputationalDependencies(dependencies);

        if (!dependencies.isEmpty())
            return Exception { SyntaxError, "The given initial value must be computationally independent." };
    }

    CSSRegisteredCustomProperty property { descriptor.name, descriptor.syntax, descriptor.inherits, WTFMove(initialValue) };
    if (!document.registerCSSProperty(WTFMove(property)))
        return Exception { InvalidModificationError, "This property has already been registered." };

    document.styleScope().didChangeStyleSheetEnvironment();

    return { };
}

DOMCSSRegisterCustomProperty* DOMCSSRegisterCustomProperty::from(DOMCSSNamespace& css)
{
    auto* supplement = static_cast<DOMCSSRegisterCustomProperty*>(Supplement<DOMCSSNamespace>::from(&css, supplementName()));
    if (!supplement) {
        auto newSupplement = makeUnique<DOMCSSRegisterCustomProperty>(css);
        supplement = newSupplement.get();
        provideTo(&css, supplementName(), WTFMove(newSupplement));
    }
    return supplement;
}

const char* DOMCSSRegisterCustomProperty::supplementName()
{
    return "DOMCSSRegisterCustomProperty";
}

}