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/*
* Copyright (C) 2011 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.
*/
#ifndef WriteBarrier_h
#define WriteBarrier_h
#include "JSValue.h"
namespace JSC {
class JSCell;
class JSGlobalData;
inline void writeBarrier(JSGlobalData&, const JSCell*, JSValue)
{
}
inline void writeBarrier(JSGlobalData&, const JSCell*, JSCell*)
{
}
typedef enum { } Unknown;
typedef JSValue* HandleSlot;
template <typename T> struct JSValueChecker {
static const bool IsJSValue = false;
};
template <> struct JSValueChecker<JSValue> {
static const bool IsJSValue = true;
};
// We have a separate base class with no constructors for use in Unions.
template <typename T> class WriteBarrierBase {
public:
COMPILE_ASSERT(!JSValueChecker<T>::IsJSValue, WriteBarrier_JSValue_is_invalid__use_unknown);
void set(JSGlobalData& globalData, const JSCell* owner, T* value)
{
this->m_cell = reinterpret_cast<JSCell*>(value);
writeBarrier(globalData, owner, this->m_cell);
#if ENABLE(JSC_ZOMBIES)
ASSERT(!isZombie(owner));
ASSERT(!isZombie(m_cell));
#endif
}
T* get() const
{
return reinterpret_cast<T*>(m_cell);
}
T* operator*() const
{
ASSERT(m_cell);
#if ENABLE(JSC_ZOMBIES)
ASSERT(!isZombie(m_cell));
#endif
return static_cast<T*>(m_cell);
}
T* operator->() const
{
ASSERT(m_cell);
return static_cast<T*>(m_cell);
}
void clear() { m_cell = 0; }
JSCell** slot() { return &m_cell; }
typedef T* (WriteBarrierBase::*UnspecifiedBoolType);
operator UnspecifiedBoolType*() const { return m_cell ? reinterpret_cast<UnspecifiedBoolType*>(1) : 0; }
bool operator!() const { return !m_cell; }
void setWithoutWriteBarrier(T* value)
{
this->m_cell = reinterpret_cast<JSCell*>(value);
#if ENABLE(JSC_ZOMBIES)
ASSERT(!m_cell || !isZombie(m_cell));
#endif
}
private:
JSCell* m_cell;
};
template <> class WriteBarrierBase<Unknown> {
public:
void set(JSGlobalData& globalData, const JSCell* owner, JSValue value)
{
#if ENABLE(JSC_ZOMBIES)
ASSERT(!isZombie(owner));
ASSERT(!value.isZombie());
#endif
m_value = JSValue::encode(value);
writeBarrier(globalData, owner, value);
}
void setWithoutWriteBarrier(JSValue value)
{
#if ENABLE(JSC_ZOMBIES)
ASSERT(!value.isZombie());
#endif
m_value = JSValue::encode(value);
}
JSValue get() const
{
return JSValue::decode(m_value);
}
void clear() { m_value = JSValue::encode(JSValue()); }
void setUndefined() { m_value = JSValue::encode(jsUndefined()); }
bool isNumber() const { return get().isNumber(); }
bool isObject() const { return get().isObject(); }
bool isNull() const { return get().isNull(); }
bool isGetterSetter() const { return get().isGetterSetter(); }
JSValue* slot()
{
union {
EncodedJSValue* v;
JSValue* slot;
} u;
u.v = &m_value;
return u.slot;
}
typedef JSValue (WriteBarrierBase::*UnspecifiedBoolType);
operator UnspecifiedBoolType*() const { return get() ? reinterpret_cast<UnspecifiedBoolType*>(1) : 0; }
bool operator!() const { return !get(); }
private:
EncodedJSValue m_value;
};
template <typename T> class WriteBarrier : public WriteBarrierBase<T> {
public:
WriteBarrier()
{
this->setWithoutWriteBarrier(0);
}
WriteBarrier(JSGlobalData& globalData, const JSCell* owner, T* value)
{
this->set(globalData, owner, value);
}
};
template <> class WriteBarrier<Unknown> : public WriteBarrierBase<Unknown> {
public:
WriteBarrier()
{
this->setWithoutWriteBarrier(JSValue());
}
WriteBarrier(JSGlobalData& globalData, const JSCell* owner, JSValue value)
{
this->set(globalData, owner, value);
}
};
template <typename U, typename V> inline bool operator==(const WriteBarrierBase<U>& lhs, const WriteBarrierBase<V>& rhs)
{
return lhs.get() == rhs.get();
}
} // namespace JSC
#endif // WriteBarrier_h
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