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/*
* Copyright (C) 2015-2016 Yusuke Suzuki <utatane.tea@gmail.com>.
*
* 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 <wtf/text/UniquedStringImpl.h>
namespace WTF {
class RegisteredSymbolImpl;
// SymbolImpl is used to represent the symbol string impl.
// It is uniqued string impl, but is not registered in Atomic String tables, so it's not atomic.
class SymbolImpl : public UniquedStringImpl {
public:
using Flags = unsigned;
static constexpr Flags s_flagDefault = 0u;
static constexpr Flags s_flagIsNullSymbol = 0b001u;
static constexpr Flags s_flagIsRegistered = 0b010u;
static constexpr Flags s_flagIsPrivate = 0b100u;
unsigned hashForSymbol() const { return m_hashForSymbolShiftedWithFlagCount >> s_flagCount; }
bool isNullSymbol() const { return m_flags & s_flagIsNullSymbol; }
bool isRegistered() const { return m_flags & s_flagIsRegistered; }
bool isPrivate() const { return m_flags & s_flagIsPrivate; }
SymbolRegistry* symbolRegistry() const;
RegisteredSymbolImpl* asRegisteredSymbolImpl();
WTF_EXPORT_PRIVATE static Ref<SymbolImpl> createNullSymbol();
WTF_EXPORT_PRIVATE static Ref<SymbolImpl> create(StringImpl& rep);
class StaticSymbolImpl final : private StringImplShape {
WTF_MAKE_NONCOPYABLE(StaticSymbolImpl);
public:
template<unsigned characterCount>
constexpr StaticSymbolImpl(const char (&characters)[characterCount], Flags flags = s_flagDefault)
: StringImplShape(s_refCountFlagIsStaticString, characterCount - 1, characters,
s_hashFlag8BitBuffer | s_hashFlagDidReportCost | StringSymbol | BufferInternal | (StringHasher::computeLiteralHashAndMaskTop8Bits(characters) << s_flagCount), ConstructWithConstExpr)
, m_hashForSymbolShiftedWithFlagCount(StringHasher::computeLiteralHashAndMaskTop8Bits(characters) << s_flagCount)
, m_flags(flags)
{
}
template<unsigned characterCount>
constexpr StaticSymbolImpl(const char16_t (&characters)[characterCount], Flags flags = s_flagDefault)
: StringImplShape(s_refCountFlagIsStaticString, characterCount - 1, characters,
s_hashFlagDidReportCost | StringSymbol | BufferInternal | (StringHasher::computeLiteralHashAndMaskTop8Bits(characters) << s_flagCount), ConstructWithConstExpr)
, m_hashForSymbolShiftedWithFlagCount(StringHasher::computeLiteralHashAndMaskTop8Bits(characters) << s_flagCount)
, m_flags(flags)
{
}
operator SymbolImpl&()
{
return *reinterpret_cast<SymbolImpl*>(this);
}
StringImpl* m_owner { nullptr }; // We do not make StaticSymbolImpl BufferSubstring. Thus we can make this nullptr.
unsigned m_hashForSymbolShiftedWithFlagCount;
Flags m_flags;
};
protected:
WTF_EXPORT_PRIVATE static unsigned nextHashForSymbol();
friend class StringImpl;
SymbolImpl(const LChar* characters, unsigned length, Ref<StringImpl>&& base, Flags flags = s_flagDefault)
: UniquedStringImpl(CreateSymbol, characters, length)
, m_owner(&base.leakRef())
, m_hashForSymbolShiftedWithFlagCount(nextHashForSymbol())
, m_flags(flags)
{
ASSERT(StringImpl::tailOffset<StringImpl*>() == OBJECT_OFFSETOF(SymbolImpl, m_owner));
}
SymbolImpl(const UChar* characters, unsigned length, Ref<StringImpl>&& base, Flags flags = s_flagDefault)
: UniquedStringImpl(CreateSymbol, characters, length)
, m_owner(&base.leakRef())
, m_hashForSymbolShiftedWithFlagCount(nextHashForSymbol())
, m_flags(flags)
{
ASSERT(StringImpl::tailOffset<StringImpl*>() == OBJECT_OFFSETOF(SymbolImpl, m_owner));
}
SymbolImpl(Flags flags = s_flagDefault)
: UniquedStringImpl(CreateSymbol)
, m_owner(StringImpl::empty())
, m_hashForSymbolShiftedWithFlagCount(nextHashForSymbol())
, m_flags(flags | s_flagIsNullSymbol)
{
ASSERT(StringImpl::tailOffset<StringImpl*>() == OBJECT_OFFSETOF(SymbolImpl, m_owner));
}
// The pointer to the owner string should be immediately following after the StringImpl layout,
// since we would like to align the layout of SymbolImpl to the one of BufferSubstring StringImpl.
StringImpl* m_owner;
unsigned m_hashForSymbolShiftedWithFlagCount;
Flags m_flags { s_flagDefault };
};
static_assert(sizeof(SymbolImpl) == sizeof(SymbolImpl::StaticSymbolImpl), "");
class PrivateSymbolImpl final : public SymbolImpl {
public:
WTF_EXPORT_PRIVATE static Ref<PrivateSymbolImpl> createNullSymbol();
WTF_EXPORT_PRIVATE static Ref<PrivateSymbolImpl> create(StringImpl& rep);
private:
PrivateSymbolImpl(const LChar* characters, unsigned length, Ref<StringImpl>&& base)
: SymbolImpl(characters, length, WTFMove(base), s_flagIsPrivate)
{
}
PrivateSymbolImpl(const UChar* characters, unsigned length, Ref<StringImpl>&& base)
: SymbolImpl(characters, length, WTFMove(base), s_flagIsPrivate)
{
}
PrivateSymbolImpl()
: SymbolImpl(s_flagIsPrivate)
{
}
};
class RegisteredSymbolImpl final : public SymbolImpl {
private:
friend class StringImpl;
friend class SymbolImpl;
friend class SymbolRegistry;
SymbolRegistry* symbolRegistry() const { return m_symbolRegistry; }
void clearSymbolRegistry() { m_symbolRegistry = nullptr; }
static Ref<RegisteredSymbolImpl> create(StringImpl& rep, SymbolRegistry&);
RegisteredSymbolImpl(const LChar* characters, unsigned length, Ref<StringImpl>&& base, SymbolRegistry& registry)
: SymbolImpl(characters, length, WTFMove(base), s_flagIsRegistered)
, m_symbolRegistry(&registry)
{
}
RegisteredSymbolImpl(const UChar* characters, unsigned length, Ref<StringImpl>&& base, SymbolRegistry& registry)
: SymbolImpl(characters, length, WTFMove(base), s_flagIsRegistered)
, m_symbolRegistry(&registry)
{
}
SymbolRegistry* m_symbolRegistry;
};
inline unsigned StringImpl::symbolAwareHash() const
{
if (isSymbol())
return static_cast<const SymbolImpl*>(this)->hashForSymbol();
return hash();
}
inline unsigned StringImpl::existingSymbolAwareHash() const
{
if (isSymbol())
return static_cast<const SymbolImpl*>(this)->hashForSymbol();
return existingHash();
}
inline SymbolRegistry* SymbolImpl::symbolRegistry() const
{
if (isRegistered())
return static_cast<const RegisteredSymbolImpl*>(this)->symbolRegistry();
return nullptr;
}
inline RegisteredSymbolImpl* SymbolImpl::asRegisteredSymbolImpl()
{
ASSERT(isRegistered());
return static_cast<RegisteredSymbolImpl*>(this);
}
#if ASSERT_ENABLED
// SymbolImpls created from StaticStringImpl will ASSERT
// in the generic ValueCheck<T>::checkConsistency
// as they are not allocated by fastMalloc.
// We don't currently have any way to detect that case
// so we ignore the consistency check for all SymbolImpls*.
template<> struct
ValueCheck<SymbolImpl*> {
static void checkConsistency(const SymbolImpl*) { }
};
template<> struct
ValueCheck<const SymbolImpl*> {
static void checkConsistency(const SymbolImpl*) { }
};
#endif // ASSERT_ENABLED
} // namespace WTF
using WTF::SymbolImpl;
using WTF::PrivateSymbolImpl;
using WTF::RegisteredSymbolImpl;