Source/WebCore/css/CSSStyleDeclaration.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"
 #include "CSSStyleDeclaration.h"

 #include "CSSPropertyNames.h"
 #include "CSSPropertyParser.h"
 #include "DeprecatedGlobalSettings.h"
 #include "Document.h"
 #include "HashTools.h"
 #include "RuntimeEnabledFeatures.h"
 #include "Settings.h"
 #include "StyledElement.h"
 #include <wtf/IsoMallocInlines.h>
 #include <wtf/Optional.h>
 #include <wtf/Variant.h>

 namespace WebCore {

 WTF_MAKE_ISO_ALLOCATED_IMPL(CSSStyleDeclaration);

 namespace {

 enum class PropertyNamePrefix {
     None, Epub, CSS, Pixel, Pos, WebKit,
 #if ENABLE(LEGACY_CSS_VENDOR_PREFIXES)
     Apple, KHTML,
 #endif
 };

 template<size_t prefixCStringLength>
 static inline bool matchesCSSPropertyNamePrefix(const StringImpl& propertyName, const char (&prefix)[prefixCStringLength])
 {
     size_t prefixLength = prefixCStringLength - 1;

     ASSERT(toASCIILower(propertyName[0]) == prefix[0]);
     const size_t offset = 1;

 #ifndef NDEBUG
     for (size_t i = 0; i < prefixLength; ++i)
         ASSERT(isASCIILower(prefix[i]));
     ASSERT(!prefix[prefixLength]);
     ASSERT(propertyName.length());
 #endif

     // The prefix within the property name must be followed by a capital letter.
     // Other characters in the prefix within the property name must be lowercase.
     if (propertyName.length() < prefixLength + 1)
         return false;

     for (size_t i = offset; i < prefixLength; ++i) {
         if (propertyName[i] != prefix[i])
             return false;
     }

     if (!isASCIIUpper(propertyName[prefixLength]))
         return false;

     return true;
 }

 static PropertyNamePrefix propertyNamePrefix(const StringImpl& propertyName)
 {
     ASSERT(propertyName.length());

     // First character of the prefix within the property name may be upper or lowercase.
     UChar firstChar = toASCIILower(propertyName[0]);
     switch (firstChar) {
 #if ENABLE(LEGACY_CSS_VENDOR_PREFIXES)
     case 'a':
         if (RuntimeEnabledFeatures::sharedFeatures().legacyCSSVendorPrefixesEnabled() && matchesCSSPropertyNamePrefix(propertyName, "apple"))
             return PropertyNamePrefix::Apple;
         break;
 #endif
     case 'c':
         if (matchesCSSPropertyNamePrefix(propertyName, "css"))
             return PropertyNamePrefix::CSS;
         break;
 #if ENABLE(LEGACY_CSS_VENDOR_PREFIXES)
     case 'k':
         if (RuntimeEnabledFeatures::sharedFeatures().legacyCSSVendorPrefixesEnabled() && matchesCSSPropertyNamePrefix(propertyName, "khtml"))
             return PropertyNamePrefix::KHTML;
         break;
 #endif
     case 'e':
         if (matchesCSSPropertyNamePrefix(propertyName, "epub"))
             return PropertyNamePrefix::Epub;
         break;
     case 'p':
         if (matchesCSSPropertyNamePrefix(propertyName, "pos"))
             return PropertyNamePrefix::Pos;
         if (matchesCSSPropertyNamePrefix(propertyName, "pixel"))
             return PropertyNamePrefix::Pixel;
         break;
     case 'w':
         if (matchesCSSPropertyNamePrefix(propertyName, "webkit"))
             return PropertyNamePrefix::WebKit;
         break;
     default:
         break;
     }
     return PropertyNamePrefix::None;
 }

 static inline void writeWebKitPrefix(char*& buffer)
 {
     *buffer++ = '-';
     *buffer++ = 'w';
     *buffer++ = 'e';
     *buffer++ = 'b';
     *buffer++ = 'k';
     *buffer++ = 'i';
     *buffer++ = 't';
     *buffer++ = '-';
 }

 static inline void writeEpubPrefix(char*& buffer)
 {
     *buffer++ = '-';
     *buffer++ = 'e';
     *buffer++ = 'p';
     *buffer++ = 'u';
     *buffer++ = 'b';
     *buffer++ = '-';
 }

 struct CSSPropertyInfo {
     CSSPropertyID propertyID;
     bool hadPixelOrPosPrefix;
 };

 static CSSPropertyInfo parseJavaScriptCSSPropertyName(const AtomString& propertyName)
 {
     using CSSPropertyInfoMap = HashMap<String, CSSPropertyInfo>;
     static NeverDestroyed<CSSPropertyInfoMap> propertyInfoCache;

     CSSPropertyInfo propertyInfo = { CSSPropertyInvalid, false };

     auto* propertyNameString = propertyName.impl();
     if (!propertyNameString)
         return propertyInfo;
     unsigned length = propertyNameString->length();
     if (!length)
         return propertyInfo;

     propertyInfo = propertyInfoCache.get().get(propertyNameString);
     if (propertyInfo.propertyID)
         return propertyInfo;

     bool hadPixelOrPosPrefix = false;

     constexpr size_t bufferSize = maxCSSPropertyNameLength + 1;
     char buffer[bufferSize];
     char* bufferPtr = buffer;
     const char* name = bufferPtr;

     unsigned i = 0;
     // Prefixes CSS, Pixel, Pos are ignored.
     // Prefixes Apple, KHTML and Webkit are transposed to "-webkit-".
     // The prefix "Epub" becomes "-epub-".
     switch (propertyNamePrefix(*propertyNameString)) {
     case PropertyNamePrefix::None:
         if (isASCIIUpper((*propertyNameString)[0]))
             return propertyInfo;
         break;
     case PropertyNamePrefix::CSS:
         i += 3;
         break;
     case PropertyNamePrefix::Pixel:
         i += 5;
         hadPixelOrPosPrefix = true;
         break;
     case PropertyNamePrefix::Pos:
         i += 3;
         hadPixelOrPosPrefix = true;
         break;
 #if ENABLE(LEGACY_CSS_VENDOR_PREFIXES)
     case PropertyNamePrefix::Apple:
     case PropertyNamePrefix::KHTML:
         ASSERT(RuntimeEnabledFeatures::sharedFeatures().legacyCSSVendorPrefixesEnabled());
         writeWebKitPrefix(bufferPtr);
         i += 5;
         break;
 #endif
     case PropertyNamePrefix::Epub:
         writeEpubPrefix(bufferPtr);
         i += 4;
         break;
     case PropertyNamePrefix::WebKit:
         writeWebKitPrefix(bufferPtr);
         i += 6;
         break;
     }

     *bufferPtr++ = toASCIILower((*propertyNameString)[i++]);

     char* bufferEnd = buffer + bufferSize;
     char* stringEnd = bufferEnd - 1;
     size_t bufferSizeLeft = stringEnd - bufferPtr;
     size_t propertySizeLeft = length - i;
     if (propertySizeLeft > bufferSizeLeft)
         return propertyInfo;

     for (; i < length; ++i) {
         UChar c = (*propertyNameString)[i];
         if (!c || !isASCII(c))
             return propertyInfo; // illegal character
         if (isASCIIUpper(c)) {
             size_t bufferSizeLeft = stringEnd - bufferPtr;
             size_t propertySizeLeft = length - i + 1;
             if (propertySizeLeft > bufferSizeLeft)
                 return propertyInfo;
             *bufferPtr++ = '-';
             *bufferPtr++ = toASCIILowerUnchecked(c);
         } else
             *bufferPtr++ = c;
         ASSERT_WITH_SECURITY_IMPLICATION(bufferPtr < bufferEnd);
     }
     ASSERT_WITH_SECURITY_IMPLICATION(bufferPtr < bufferEnd);
     *bufferPtr = '\0';

     unsigned outputLength = bufferPtr - buffer;
 #if PLATFORM(IOS_FAMILY)
     cssPropertyNameIOSAliasing(buffer, name, outputLength);
 #endif

     auto* hashTableEntry = findProperty(name, outputLength);
     if (auto propertyID = hashTableEntry ? hashTableEntry->id : 0) {
         auto id = static_cast<CSSPropertyID>(propertyID);
         propertyInfo.hadPixelOrPosPrefix = hadPixelOrPosPrefix;
         propertyInfo.propertyID = id;
         propertyInfoCache.get().add(propertyNameString, propertyInfo);
     }
     return propertyInfo;
 }

 static CSSPropertyInfo propertyInfoFromJavaScriptCSSPropertyName(const AtomString& propertyName, const Settings* settings)
 {
     auto propertyInfo = parseJavaScriptCSSPropertyName(propertyName);
     auto id = propertyInfo.propertyID;
     if (!isEnabledCSSProperty(id) || !isCSSPropertyEnabledBySettings(id, settings))
         return { CSSPropertyInvalid, false };
     return propertyInfo;
 }

 }

 CSSPropertyID CSSStyleDeclaration::getCSSPropertyIDFromJavaScriptPropertyName(const AtomString& propertyName)
 {
     return propertyInfoFromJavaScriptCSSPropertyName(propertyName, nullptr).propertyID;
 }

 Optional<Variant<String, double>> CSSStyleDeclaration::namedItem(const AtomString& propertyName)
 {
     auto* settings = parentElement() ? &parentElement()->document().settings() : nullptr;
     auto propertyInfo = propertyInfoFromJavaScriptCSSPropertyName(propertyName, settings);
     if (!propertyInfo.propertyID)
         return WTF::nullopt;

     auto value = getPropertyCSSValueInternal(propertyInfo.propertyID);
     if (!value) {
         // If the property is a shorthand property (such as "padding"), it can only be accessed using getPropertyValue.
         return Variant<String, double> { getPropertyValueInternal(propertyInfo.propertyID) };
     }

     if (propertyInfo.hadPixelOrPosPrefix && is<CSSPrimitiveValue>(*value)) {
         // Call this version of the getter so that, e.g., pixelTop returns top as a number
         // in pixel units and posTop should does the same _if_ this is a positioned element.
         // FIXME: If not a positioned element, MSIE documentation says posTop should return 0; this rule is not implemented.
         return Variant<String, double> { downcast<CSSPrimitiveValue>(*value).floatValue(CSSUnitType::CSS_PX) };
     }

     return Variant<String, double> { value->cssText() };
 }

 ExceptionOr<void> CSSStyleDeclaration::setNamedItem(const AtomString& propertyName, String value, bool& propertySupported)
 {
     auto* settings = parentElement() ? &parentElement()->document().settings() : nullptr;
     auto propertyInfo = propertyInfoFromJavaScriptCSSPropertyName(propertyName, settings);
     if (!propertyInfo.propertyID) {
         propertySupported = false;
         return { };
     }

     propertySupported = true;

     if (propertyInfo.hadPixelOrPosPrefix)
         value.append("px");

     bool important = false;
     if (DeprecatedGlobalSettings::shouldRespectPriorityInCSSAttributeSetters()) {
         auto importantIndex = value.findIgnoringASCIICase("!important");
         if (importantIndex && importantIndex != notFound) {
             important = true;
             value = value.left(importantIndex - 1);
         }
     }

     auto setPropertyInternalResult = setPropertyInternal(propertyInfo.propertyID, value, important);
     if (setPropertyInternalResult.hasException())
         return setPropertyInternalResult.releaseException();

     return { };
 }

 Vector<AtomString> CSSStyleDeclaration::supportedPropertyNames() const
 {
     static unsigned numNames = 0;
     static const AtomString* const cssPropertyNames = [] {
         String names[numCSSProperties];
         for (int i = 0; i < numCSSProperties; ++i) {
             CSSPropertyID id = static_cast<CSSPropertyID>(firstCSSProperty + i);
             // FIXME: Should take account for flags in settings().
             if (isEnabledCSSProperty(id))
                 names[numNames++] = getJSPropertyName(id);
         }
         std::sort(&names[0], &names[numNames], WTF::codePointCompareLessThan);
         auto* identifiers = new AtomString[numNames];
         for (unsigned i = 0; i < numNames; ++i)
             identifiers[i] = names[i];
         return identifiers;
     }();

     Vector<AtomString> result;
     result.reserveInitialCapacity(numNames);

     for (unsigned i = 0; i < numNames; ++i)
         result.uncheckedAppend(cssPropertyNames[i]);

     return result;
 }

 String CSSStyleDeclaration::cssFloat()
 {
     return getPropertyValueInternal(CSSPropertyFloat);
 }

 ExceptionOr<void> CSSStyleDeclaration::setCssFloat(const String& value)
 {
     auto result = setPropertyInternal(CSSPropertyFloat, value, false /* important */);
     if (result.hasException())
         return result.releaseException();
     return { };
 }

 }
	/*
	* Copyright (C) 2017 Apple Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
	* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
	* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	* THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"
	#include "CSSStyleDeclaration.h"

	#include "CSSPropertyNames.h"
	#include "CSSPropertyParser.h"
	#include "DeprecatedGlobalSettings.h"
	#include "Document.h"
	#include "HashTools.h"
	#include "RuntimeEnabledFeatures.h"
	#include "Settings.h"
	#include "StyledElement.h"
	#include <wtf/IsoMallocInlines.h>
	#include <wtf/Optional.h>
	#include <wtf/Variant.h>

	namespace WebCore {

	WTF_MAKE_ISO_ALLOCATED_IMPL(CSSStyleDeclaration);

	namespace {

	enum class PropertyNamePrefix {
	None, Epub, CSS, Pixel, Pos, WebKit,
	#if ENABLE(LEGACY_CSS_VENDOR_PREFIXES)
	Apple, KHTML,
	#endif
	};

	template<size_t prefixCStringLength>
	static inline bool matchesCSSPropertyNamePrefix(const StringImpl& propertyName, const char (&prefix)[prefixCStringLength])
	{
	size_t prefixLength = prefixCStringLength - 1;

	ASSERT(toASCIILower(propertyName[0]) == prefix[0]);
	const size_t offset = 1;

	#ifndef NDEBUG
	for (size_t i = 0; i < prefixLength; ++i)
	ASSERT(isASCIILower(prefix[i]));
	ASSERT(!prefix[prefixLength]);
	ASSERT(propertyName.length());
	#endif

	// The prefix within the property name must be followed by a capital letter.
	// Other characters in the prefix within the property name must be lowercase.
	if (propertyName.length() < prefixLength + 1)
	return false;

	for (size_t i = offset; i < prefixLength; ++i) {
	if (propertyName[i] != prefix[i])
	return false;
	}

	if (!isASCIIUpper(propertyName[prefixLength]))
	return false;

	return true;
	}

	static PropertyNamePrefix propertyNamePrefix(const StringImpl& propertyName)
	{
	ASSERT(propertyName.length());

	// First character of the prefix within the property name may be upper or lowercase.
	UChar firstChar = toASCIILower(propertyName[0]);
	switch (firstChar) {
	#if ENABLE(LEGACY_CSS_VENDOR_PREFIXES)
	case 'a':
	if (RuntimeEnabledFeatures::sharedFeatures().legacyCSSVendorPrefixesEnabled() && matchesCSSPropertyNamePrefix(propertyName, "apple"))
	return PropertyNamePrefix::Apple;
	break;
	#endif
	case 'c':
	if (matchesCSSPropertyNamePrefix(propertyName, "css"))
	return PropertyNamePrefix::CSS;
	break;
	#if ENABLE(LEGACY_CSS_VENDOR_PREFIXES)
	case 'k':
	if (RuntimeEnabledFeatures::sharedFeatures().legacyCSSVendorPrefixesEnabled() && matchesCSSPropertyNamePrefix(propertyName, "khtml"))
	return PropertyNamePrefix::KHTML;
	break;
	#endif
	case 'e':
	if (matchesCSSPropertyNamePrefix(propertyName, "epub"))
	return PropertyNamePrefix::Epub;
	break;
	case 'p':
	if (matchesCSSPropertyNamePrefix(propertyName, "pos"))
	return PropertyNamePrefix::Pos;
	if (matchesCSSPropertyNamePrefix(propertyName, "pixel"))
	return PropertyNamePrefix::Pixel;
	break;
	case 'w':
	if (matchesCSSPropertyNamePrefix(propertyName, "webkit"))
	return PropertyNamePrefix::WebKit;
	break;
	default:
	break;
	}
	return PropertyNamePrefix::None;
	}

	static inline void writeWebKitPrefix(char*& buffer)
	{
	*buffer++ = '-';
	*buffer++ = 'w';
	*buffer++ = 'e';
	*buffer++ = 'b';
	*buffer++ = 'k';
	*buffer++ = 'i';
	*buffer++ = 't';
	*buffer++ = '-';
	}

	static inline void writeEpubPrefix(char*& buffer)
	{
	*buffer++ = '-';
	*buffer++ = 'e';
	*buffer++ = 'p';
	*buffer++ = 'u';
	*buffer++ = 'b';
	*buffer++ = '-';
	}

	struct CSSPropertyInfo {
	CSSPropertyID propertyID;
	bool hadPixelOrPosPrefix;
	};

	static CSSPropertyInfo parseJavaScriptCSSPropertyName(const AtomString& propertyName)
	{
	using CSSPropertyInfoMap = HashMap<String, CSSPropertyInfo>;
	static NeverDestroyed<CSSPropertyInfoMap> propertyInfoCache;

	CSSPropertyInfo propertyInfo = { CSSPropertyInvalid, false };

	auto* propertyNameString = propertyName.impl();
	if (!propertyNameString)
	return propertyInfo;
	unsigned length = propertyNameString->length();
	if (!length)
	return propertyInfo;

	propertyInfo = propertyInfoCache.get().get(propertyNameString);
	if (propertyInfo.propertyID)
	return propertyInfo;

	bool hadPixelOrPosPrefix = false;

	constexpr size_t bufferSize = maxCSSPropertyNameLength + 1;
	char buffer[bufferSize];
	char* bufferPtr = buffer;
	const char* name = bufferPtr;

	unsigned i = 0;
	// Prefixes CSS, Pixel, Pos are ignored.
	// Prefixes Apple, KHTML and Webkit are transposed to "-webkit-".
	// The prefix "Epub" becomes "-epub-".
	switch (propertyNamePrefix(*propertyNameString)) {
	case PropertyNamePrefix::None:
	if (isASCIIUpper((*propertyNameString)[0]))
	return propertyInfo;
	break;
	case PropertyNamePrefix::CSS:
	i += 3;
	break;
	case PropertyNamePrefix::Pixel:
	i += 5;
	hadPixelOrPosPrefix = true;
	break;
	case PropertyNamePrefix::Pos:
	i += 3;
	hadPixelOrPosPrefix = true;
	break;
	#if ENABLE(LEGACY_CSS_VENDOR_PREFIXES)
	case PropertyNamePrefix::Apple:
	case PropertyNamePrefix::KHTML:
	ASSERT(RuntimeEnabledFeatures::sharedFeatures().legacyCSSVendorPrefixesEnabled());
	writeWebKitPrefix(bufferPtr);
	i += 5;
	break;
	#endif
	case PropertyNamePrefix::Epub:
	writeEpubPrefix(bufferPtr);
	i += 4;
	break;
	case PropertyNamePrefix::WebKit:
	writeWebKitPrefix(bufferPtr);
	i += 6;
	break;
	}

	bufferPtr++ = toASCIILower((propertyNameString)[i++]);

	char* bufferEnd = buffer + bufferSize;
	char* stringEnd = bufferEnd - 1;
	size_t bufferSizeLeft = stringEnd - bufferPtr;
	size_t propertySizeLeft = length - i;
	if (propertySizeLeft > bufferSizeLeft)
	return propertyInfo;

	for (; i < length; ++i) {
	UChar c = (*propertyNameString)[i];
	if (!c \|\| !isASCII(c))
	return propertyInfo; // illegal character
	if (isASCIIUpper(c)) {
	size_t bufferSizeLeft = stringEnd - bufferPtr;
	size_t propertySizeLeft = length - i + 1;
	if (propertySizeLeft > bufferSizeLeft)
	return propertyInfo;
	*bufferPtr++ = '-';
	*bufferPtr++ = toASCIILowerUnchecked(c);
	} else
	*bufferPtr++ = c;
	ASSERT_WITH_SECURITY_IMPLICATION(bufferPtr < bufferEnd);
	}
	ASSERT_WITH_SECURITY_IMPLICATION(bufferPtr < bufferEnd);
	*bufferPtr = '\0';

	unsigned outputLength = bufferPtr - buffer;
	#if PLATFORM(IOS_FAMILY)
	cssPropertyNameIOSAliasing(buffer, name, outputLength);
	#endif

	auto* hashTableEntry = findProperty(name, outputLength);
	if (auto propertyID = hashTableEntry ? hashTableEntry->id : 0) {
	auto id = static_cast<CSSPropertyID>(propertyID);
	propertyInfo.hadPixelOrPosPrefix = hadPixelOrPosPrefix;
	propertyInfo.propertyID = id;
	propertyInfoCache.get().add(propertyNameString, propertyInfo);
	}
	return propertyInfo;
	}

	static CSSPropertyInfo propertyInfoFromJavaScriptCSSPropertyName(const AtomString& propertyName, const Settings* settings)
	{
	auto propertyInfo = parseJavaScriptCSSPropertyName(propertyName);
	auto id = propertyInfo.propertyID;
	if (!isEnabledCSSProperty(id) \|\| !isCSSPropertyEnabledBySettings(id, settings))
	return { CSSPropertyInvalid, false };
	return propertyInfo;
	}

	}

	CSSPropertyID CSSStyleDeclaration::getCSSPropertyIDFromJavaScriptPropertyName(const AtomString& propertyName)
	{
	return propertyInfoFromJavaScriptCSSPropertyName(propertyName, nullptr).propertyID;
	}

	Optional<Variant<String, double>> CSSStyleDeclaration::namedItem(const AtomString& propertyName)
	{
	auto* settings = parentElement() ? &parentElement()->document().settings() : nullptr;
	auto propertyInfo = propertyInfoFromJavaScriptCSSPropertyName(propertyName, settings);
	if (!propertyInfo.propertyID)
	return WTF::nullopt;

	auto value = getPropertyCSSValueInternal(propertyInfo.propertyID);
	if (!value) {
	// If the property is a shorthand property (such as "padding"), it can only be accessed using getPropertyValue.
	return Variant<String, double> { getPropertyValueInternal(propertyInfo.propertyID) };
	}

	if (propertyInfo.hadPixelOrPosPrefix && is<CSSPrimitiveValue>(*value)) {
	// Call this version of the getter so that, e.g., pixelTop returns top as a number
	// in pixel units and posTop should does the same _if_ this is a positioned element.
	// FIXME: If not a positioned element, MSIE documentation says posTop should return 0; this rule is not implemented.
	return Variant<String, double> { downcast<CSSPrimitiveValue>(*value).floatValue(CSSUnitType::CSS_PX) };
	}

	return Variant<String, double> { value->cssText() };
	}

	ExceptionOr<void> CSSStyleDeclaration::setNamedItem(const AtomString& propertyName, String value, bool& propertySupported)
	{
	auto* settings = parentElement() ? &parentElement()->document().settings() : nullptr;
	auto propertyInfo = propertyInfoFromJavaScriptCSSPropertyName(propertyName, settings);
	if (!propertyInfo.propertyID) {
	propertySupported = false;
	return { };
	}

	propertySupported = true;

	if (propertyInfo.hadPixelOrPosPrefix)
	value.append("px");

	bool important = false;
	if (DeprecatedGlobalSettings::shouldRespectPriorityInCSSAttributeSetters()) {
	auto importantIndex = value.findIgnoringASCIICase("!important");
	if (importantIndex && importantIndex != notFound) {
	important = true;
	value = value.left(importantIndex - 1);
	}
	}

	auto setPropertyInternalResult = setPropertyInternal(propertyInfo.propertyID, value, important);
	if (setPropertyInternalResult.hasException())
	return setPropertyInternalResult.releaseException();

	return { };
	}

	Vector<AtomString> CSSStyleDeclaration::supportedPropertyNames() const
	{
	static unsigned numNames = 0;
	static const AtomString* const cssPropertyNames = [] {
	String names[numCSSProperties];
	for (int i = 0; i < numCSSProperties; ++i) {
	CSSPropertyID id = static_cast<CSSPropertyID>(firstCSSProperty + i);
	// FIXME: Should take account for flags in settings().
	if (isEnabledCSSProperty(id))
	names[numNames++] = getJSPropertyName(id);
	}
	std::sort(&names[0], &names[numNames], WTF::codePointCompareLessThan);
	auto* identifiers = new AtomString[numNames];
	for (unsigned i = 0; i < numNames; ++i)
	identifiers[i] = names[i];
	return identifiers;
	}();

	Vector<AtomString> result;
	result.reserveInitialCapacity(numNames);

	for (unsigned i = 0; i < numNames; ++i)
	result.uncheckedAppend(cssPropertyNames[i]);

	return result;
	}

	String CSSStyleDeclaration::cssFloat()
	{
	return getPropertyValueInternal(CSSPropertyFloat);
	}

	ExceptionOr<void> CSSStyleDeclaration::setCssFloat(const String& value)
	{
	auto result = setPropertyInternal(CSSPropertyFloat, value, false /* important */);
	if (result.hasException())
	return result.releaseException();
	return { };
	}

	}