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/*
* Copyright (C) 2008, 2009 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 COMPUTER, INC. ``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 COMPUTER, INC. OR
* 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 StructureTransitionTable_h
#define StructureTransitionTable_h
#include "WeakGCMap.h"
#include <wtf/HashFunctions.h>
#include <wtf/OwnPtr.h>
#include <wtf/RefPtr.h>
#include <wtf/text/StringImpl.h>
namespace JSC {
class JSCell;
class Structure;
class StructureTransitionTable {
static const intptr_t UsingSingleSlotFlag = 1;
struct Hash {
typedef std::pair<RefPtr<StringImpl>, unsigned> Key;
static unsigned hash(const Key& p)
{
return p.first->existingHash();
}
static bool equal(const Key& a, const Key& b)
{
return a == b;
}
static const bool safeToCompareToEmptyOrDeleted = true;
};
struct WeakGCMapFinalizerCallback {
static void* finalizerContextFor(Hash::Key)
{
return 0;
}
static inline Hash::Key keyForFinalizer(void* context, Structure* structure)
{
return keyForWeakGCMapFinalizer(context, structure);
}
};
typedef WeakGCMap<Hash::Key, Structure, WeakGCMapFinalizerCallback, Hash> TransitionMap;
static Hash::Key keyForWeakGCMapFinalizer(void* context, Structure*);
public:
StructureTransitionTable()
: m_data(UsingSingleSlotFlag)
{
}
~StructureTransitionTable()
{
if (!isUsingSingleSlot()) {
delete map();
return;
}
WeakImpl* impl = this->weakImpl();
if (!impl)
return;
WeakSet::deallocate(impl);
}
inline void add(JSGlobalData&, Structure*);
inline bool contains(StringImpl* rep, unsigned attributes) const;
inline Structure* get(StringImpl* rep, unsigned attributes) const;
private:
bool isUsingSingleSlot() const
{
return m_data & UsingSingleSlotFlag;
}
TransitionMap* map() const
{
ASSERT(!isUsingSingleSlot());
return reinterpret_cast<TransitionMap*>(m_data);
}
WeakImpl* weakImpl() const
{
ASSERT(isUsingSingleSlot());
return reinterpret_cast<WeakImpl*>(m_data & ~UsingSingleSlotFlag);
}
void setMap(TransitionMap* map)
{
ASSERT(isUsingSingleSlot());
if (WeakImpl* impl = this->weakImpl())
WeakSet::deallocate(impl);
// This implicitly clears the flag that indicates we're using a single transition
m_data = reinterpret_cast<intptr_t>(map);
ASSERT(!isUsingSingleSlot());
}
Structure* singleTransition() const
{
ASSERT(isUsingSingleSlot());
if (WeakImpl* impl = this->weakImpl()) {
if (impl->state() == WeakImpl::Live)
return reinterpret_cast<Structure*>(impl->jsValue().asCell());
}
return 0;
}
void setSingleTransition(JSGlobalData&, Structure* structure)
{
ASSERT(isUsingSingleSlot());
if (WeakImpl* impl = this->weakImpl())
WeakSet::deallocate(impl);
WeakImpl* impl = WeakSet::allocate(reinterpret_cast<JSCell*>(structure));
m_data = reinterpret_cast<intptr_t>(impl) | UsingSingleSlotFlag;
}
intptr_t m_data;
};
} // namespace JSC
#endif // StructureTransitionTable_h
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