#include "config.h"
#include "SmallStrings.h"
#include "JSGlobalObject.h"
#include "JSString.h"
#include <wtf/Noncopyable.h>
#include <wtf/PassOwnPtr.h>
namespace JSC {
static inline bool isMarked(JSCell* string)
{
return string && Heap::isMarked(string);
}
class SmallStringsStorage {
WTF_MAKE_NONCOPYABLE(SmallStringsStorage); WTF_MAKE_FAST_ALLOCATED;
public:
SmallStringsStorage();
StringImpl* rep(unsigned char character)
{
return m_reps[character].get();
}
private:
static const unsigned singleCharacterStringCount = maxSingleCharacterString + 1;
RefPtr<StringImpl> m_reps[singleCharacterStringCount];
};
SmallStringsStorage::SmallStringsStorage()
{
UChar* characterBuffer = 0;
RefPtr<StringImpl> baseString = StringImpl::createUninitialized(singleCharacterStringCount, characterBuffer);
for (unsigned i = 0; i < singleCharacterStringCount; ++i) {
characterBuffer[i] = i;
m_reps[i] = StringImpl::create(baseString, i, 1);
}
}
SmallStrings::SmallStrings()
{
COMPILE_ASSERT(singleCharacterStringCount == sizeof(m_singleCharacterStrings) / sizeof(m_singleCharacterStrings[0]), IsNumCharactersConstInSyncWithClassUsage);
clear();
}
SmallStrings::~SmallStrings()
{
}
void SmallStrings::visitChildren(HeapRootVisitor& heapRootMarker)
{
bool isAnyStringMarked = isMarked(m_emptyString);
for (unsigned i = 0; i < singleCharacterStringCount && !isAnyStringMarked; ++i)
isAnyStringMarked = isMarked(m_singleCharacterStrings[i]);
if (!isAnyStringMarked) {
clear();
return;
}
if (m_emptyString)
heapRootMarker.mark(&m_emptyString);
for (unsigned i = 0; i < singleCharacterStringCount; ++i) {
if (m_singleCharacterStrings[i])
heapRootMarker.mark(&m_singleCharacterStrings[i]);
}
}
void SmallStrings::clear()
{
m_emptyString = 0;
for (unsigned i = 0; i < singleCharacterStringCount; ++i)
m_singleCharacterStrings[i] = 0;
}
unsigned SmallStrings::count() const
{
unsigned count = 0;
if (m_emptyString)
++count;
for (unsigned i = 0; i < singleCharacterStringCount; ++i) {
if (m_singleCharacterStrings[i])
++count;
}
return count;
}
void SmallStrings::createEmptyString(JSGlobalData* globalData)
{
ASSERT(!m_emptyString);
m_emptyString = new (globalData) JSString(globalData, "", JSString::HasOtherOwner);
}
void SmallStrings::createSingleCharacterString(JSGlobalData* globalData, unsigned char character)
{
if (!m_storage)
m_storage = adoptPtr(new SmallStringsStorage);
ASSERT(!m_singleCharacterStrings[character]);
m_singleCharacterStrings[character] = new (globalData) JSString(globalData, PassRefPtr<StringImpl>(m_storage->rep(character)), JSString::HasOtherOwner);
}
StringImpl* SmallStrings::singleCharacterStringRep(unsigned char character)
{
if (!m_storage)
m_storage = adoptPtr(new SmallStringsStorage);
return m_storage->rep(character);
}
}