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/*
* Copyright (C) 2021 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.
*/
#pragma once
#include "QualifiedName.h"
#include <wtf/NeverDestroyed.h>
#include <wtf/Vector.h>
#include <wtf/text/AtomString.h>
namespace WebCore {
class HTMLNameCache {
public:
ALWAYS_INLINE static QualifiedName makeAttributeQualifiedName(Span<const UChar> string)
{
return makeQualifiedName(string);
}
ALWAYS_INLINE static AtomString makeAttributeValue(Span<const UChar> string)
{
return makeAtomString(string);
}
ALWAYS_INLINE static void clear()
{
// FIXME (webkit.org/b/230019): We should try to find more opportunities to clear this cache without hindering this performance optimization.
atomStringCache().fill({ });
qualifiedNameCache().fill({ });
}
private:
ALWAYS_INLINE static AtomString makeAtomString(Span<const UChar> string)
{
if (string.empty())
return emptyAtom();
auto length = string.size();
if (length > maxStringLengthForCache)
return AtomString(string.data(), length);
auto firstCharacter = string[0];
auto lastCharacter = string[length - 1];
auto& slot = atomStringCacheSlot(firstCharacter, lastCharacter, length);
if (!equal(slot.impl(), string.data(), length)) {
AtomString result(string.data(), length);
slot = result;
return result;
}
return slot;
}
ALWAYS_INLINE static QualifiedName makeQualifiedName(Span<const UChar> string)
{
if (string.empty())
return nullQName();
auto length = string.size();
if (length > maxStringLengthForCache)
return QualifiedName(nullAtom(), AtomString(string.data(), length), nullAtom());
auto firstCharacter = string[0];
auto lastCharacter = string[length - 1];
auto& slot = qualifiedNameCacheSlot(firstCharacter, lastCharacter, length);
if (!slot || !equal(slot->m_localName.impl(), string.data(), length)) {
QualifiedName result(nullAtom(), AtomString(string.data(), length), nullAtom());
slot = result.impl();
return result;
}
return *slot;
}
ALWAYS_INLINE static size_t slotIndex(UChar firstCharacter, UChar lastCharacter, UChar length)
{
unsigned hash = (firstCharacter << 6) ^ ((lastCharacter << 14) ^ firstCharacter);
hash += (hash >> 14) + (length << 14);
hash ^= hash << 14;
return (hash + (hash >> 6)) % capacity;
}
ALWAYS_INLINE static AtomString& atomStringCacheSlot(UChar firstCharacter, UChar lastCharacter, UChar length)
{
auto index = slotIndex(firstCharacter, lastCharacter, length);
return atomStringCache()[index];
}
ALWAYS_INLINE static RefPtr<QualifiedName::QualifiedNameImpl>& qualifiedNameCacheSlot(UChar firstCharacter, UChar lastCharacter, UChar length)
{
auto index = slotIndex(firstCharacter, lastCharacter, length);
return qualifiedNameCache()[index];
}
static constexpr auto maxStringLengthForCache = 36;
static constexpr auto capacity = 512;
using AtomStringCache = std::array<AtomString, capacity>;
using QualifiedNameCache = std::array<RefPtr<QualifiedName::QualifiedNameImpl>, capacity>;
static AtomStringCache& atomStringCache();
static QualifiedNameCache& qualifiedNameCache();
};
} // namespace WebCore
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