#include "config.h"
#include "SmallStrings.h"
#include "JSGlobalObject.h"
#include "JSString.h"
#include <wtf/Noncopyable.h>
namespace JSC {
static const unsigned numCharactersToStore = 0x100;
static inline bool isMarked(JSString* string)
{
return string && Heap::isCellMarked(string);
}
class SmallStringsStorage : public Noncopyable {
public:
SmallStringsStorage();
UString::Rep* rep(unsigned char character) { return &m_reps[character]; }
private:
UString::Rep m_reps[numCharactersToStore];
};
SmallStringsStorage::SmallStringsStorage()
{
UChar* characterBuffer = 0;
RefPtr<UStringImpl> baseString = UStringImpl::createUninitialized(numCharactersToStore, characterBuffer);
for (unsigned i = 0; i < numCharactersToStore; ++i) {
characterBuffer[i] = i;
new (&m_reps[i]) UString::Rep(&characterBuffer[i], 1, PassRefPtr<UStringImpl>(baseString));
}
}
SmallStrings::SmallStrings()
{
COMPILE_ASSERT(numCharactersToStore == sizeof(m_singleCharacterStrings) / sizeof(m_singleCharacterStrings[0]), IsNumCharactersConstInSyncWithClassUsage);
clear();
}
SmallStrings::~SmallStrings()
{
}
void SmallStrings::markChildren(MarkStack& markStack)
{
bool isAnyStringMarked = isMarked(m_emptyString);
for (unsigned i = 0; i < numCharactersToStore && !isAnyStringMarked; ++i)
isAnyStringMarked = isMarked(m_singleCharacterStrings[i]);
if (!isAnyStringMarked) {
clear();
return;
}
if (m_emptyString)
markStack.append(m_emptyString);
for (unsigned i = 0; i < numCharactersToStore; ++i) {
if (m_singleCharacterStrings[i])
markStack.append(m_singleCharacterStrings[i]);
}
}
void SmallStrings::clear()
{
m_emptyString = 0;
for (unsigned i = 0; i < numCharactersToStore; ++i)
m_singleCharacterStrings[i] = 0;
}
unsigned SmallStrings::count() const
{
unsigned count = 0;
if (m_emptyString)
++count;
for (unsigned i = 0; i < numCharactersToStore; ++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.set(new SmallStringsStorage);
ASSERT(!m_singleCharacterStrings[character]);
m_singleCharacterStrings[character] = new (globalData) JSString(globalData, m_storage->rep(character), JSString::HasOtherOwner);
}
UString::Rep* SmallStrings::singleCharacterStringRep(unsigned char character)
{
if (!m_storage)
m_storage.set(new SmallStringsStorage);
return m_storage->rep(character);
}
}