StructureTransitionTable.h [plain text]
#ifndef StructureTransitionTable_h
#define StructureTransitionTable_h
#include "UString.h"
#include <wtf/HashFunctions.h>
#include <wtf/HashMap.h>
#include <wtf/HashTraits.h>
#include <wtf/RefPtr.h>
namespace JSC {
class Structure;
struct StructureTransitionTableHash {
typedef std::pair<RefPtr<UString::Rep>, unsigned> Key;
static unsigned hash(const Key& p)
{
return p.first->computedHash();
}
static bool equal(const Key& a, const Key& b)
{
return a == b;
}
static const bool safeToCompareToEmptyOrDeleted = true;
};
struct StructureTransitionTableHashTraits {
typedef WTF::HashTraits<RefPtr<UString::Rep> > FirstTraits;
typedef WTF::GenericHashTraits<unsigned> SecondTraits;
typedef std::pair<FirstTraits::TraitType, SecondTraits::TraitType > TraitType;
static const bool emptyValueIsZero = FirstTraits::emptyValueIsZero && SecondTraits::emptyValueIsZero;
static TraitType emptyValue() { return std::make_pair(FirstTraits::emptyValue(), SecondTraits::emptyValue()); }
static const bool needsDestruction = FirstTraits::needsDestruction || SecondTraits::needsDestruction;
static void constructDeletedValue(TraitType& slot) { FirstTraits::constructDeletedValue(slot.first); }
static bool isDeletedValue(const TraitType& value) { return FirstTraits::isDeletedValue(value.first); }
};
class StructureTransitionTable {
typedef std::pair<Structure*, Structure*> Transition;
typedef HashMap<StructureTransitionTableHash::Key, Transition, StructureTransitionTableHash, StructureTransitionTableHashTraits> TransitionTable;
public:
inline bool contains(const StructureTransitionTableHash::Key&, JSCell* specificValue);
inline Structure* get(const StructureTransitionTableHash::Key&, JSCell* specificValue) const;
bool hasTransition(const StructureTransitionTableHash::Key& key)
{
return m_table.contains(key);
}
void remove(const StructureTransitionTableHash::Key& key, JSCell* specificValue)
{
TransitionTable::iterator find = m_table.find(key);
if (!specificValue)
find->second.first = 0;
else
find->second.second = 0;
if (!find->second.first && !find->second.second)
m_table.remove(find);
}
void add(const StructureTransitionTableHash::Key& key, Structure* structure, JSCell* specificValue)
{
if (!specificValue) {
TransitionTable::iterator find = m_table.find(key);
if (find == m_table.end())
m_table.add(key, Transition(structure, 0));
else
find->second.first = structure;
} else {
ASSERT(!m_table.contains(key));
m_table.add(key, Transition(0, structure));
}
}
private:
TransitionTable m_table;
};
}
#endif // StructureTransitionTable_h