StructureTransitionTable.h [plain text]
#ifndef StructureTransitionTable_h
#define StructureTransitionTable_h
#include "UString.h"
#include "WeakGCMap.h"
#include <wtf/HashFunctions.h>
#include <wtf/OwnPtr.h>
#include <wtf/RefPtr.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);
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;
};
}
#endif // StructureTransitionTable_h