RefPtr<AtomicStringImpl> JSRopeString::resolveRopeToExistingAtomicString(ExecState* exec) const
{
if (length() > maxLengthForOnStackResolve) {
resolveRope(exec);
if (RefPtr<AtomicStringImpl> existingAtomicString = AtomicStringImpl::lookUp(m_value.impl())) {
m_value = *existingAtomicString;
setIs8Bit(m_value.impl()->is8Bit());
clearFibers();
return existingAtomicString;
}
return nullptr;
}
if (is8Bit()) {
LChar buffer[maxLengthForOnStackResolve];
resolveRopeInternal8(buffer);
if (RefPtr<AtomicStringImpl> existingAtomicString = AtomicStringImpl::lookUp(buffer, length())) {
m_value = *existingAtomicString;
setIs8Bit(m_value.impl()->is8Bit());
clearFibers();
return existingAtomicString;
}
} else {
UChar buffer[maxLengthForOnStackResolve];
resolveRopeInternal16(buffer);
if (RefPtr<AtomicStringImpl> existingAtomicString = AtomicStringImpl::lookUp(buffer, length())) {
m_value = *existingAtomicString;
setIs8Bit(m_value.impl()->is8Bit());
clearFibers();
return existingAtomicString;
}
}
return nullptr;
}
void JSRopeString::resolveRopeToAtomicString(ExecState* exec) const
{
if (length() > maxLengthForOnStackResolve) {
resolveRope(exec);
m_value = AtomicString(m_value);
setIs8Bit(m_value.impl()->is8Bit());
return;
}
if (is8Bit()) {
LChar buffer[maxLengthForOnStackResolve];
resolveRopeInternal8(buffer);
m_value = AtomicString(buffer, length());
setIs8Bit(m_value.impl()->is8Bit());
} else {
UChar buffer[maxLengthForOnStackResolve];
resolveRopeInternal16(buffer);
m_value = AtomicString(buffer, length());
setIs8Bit(m_value.impl()->is8Bit());
}
clearFibers();
// If we resolved a string that didn't previously exist, notify the heap that we've grown.
if (m_value.impl()->hasOneRef())
Heap::heap(this)->reportExtraMemoryAllocated(m_value.impl()->cost());
}
JSString* JSRopeString::getIndexSlowCase(ExecState* exec, unsigned i)
{
ASSERT(isRope());
resolveRope(exec);
// Return a safe no-value result, this should never be used, since the excetion will be thrown.
if (exec->exception())
return jsEmptyString(exec);
ASSERT(!isRope());
RELEASE_ASSERT(i < m_value.length());
return jsSingleCharacterSubstring(exec, m_value, i);
}
TiString* TiString::getIndexSlowCase(TiExcState* exec, unsigned i)
{
ASSERT(isRope());
resolveRope(exec);
// Return a safe no-value result, this should never be used, since the excetion will be thrown.
if (exec->exception())
return jsString(exec, "");
ASSERT(!isRope());
ASSERT(i < m_value.size());
return jsSingleCharacterSubstring(exec, m_value, i);
}
// This function construsts a substring out of a rope without flattening by reusing the existing fibers.
// This can reduce memory usage substantially. Since traversing ropes is slow the function will revert
// back to flattening if the rope turns out to be long.
TiString* TiString::substringFromRope(TiExcState* exec, unsigned substringStart, unsigned substringLength)
{
ASSERT(isRope());
ASSERT(substringLength);
TiGlobalData* globalData = &exec->globalData();
UString substringFibers[3];
unsigned fiberCount = 0;
unsigned substringFiberCount = 0;
unsigned substringEnd = substringStart + substringLength;
unsigned fiberEnd = 0;
RopeIterator end;
for (RopeIterator it(m_fibers.data(), m_fiberCount); it != end; ++it) {
++fiberCount;
StringImpl* fiberString = *it;
unsigned fiberStart = fiberEnd;
fiberEnd = fiberStart + fiberString->length();
if (fiberEnd <= substringStart)
continue;
unsigned copyStart = std::max(substringStart, fiberStart);
unsigned copyEnd = std::min(substringEnd, fiberEnd);
if (copyStart == fiberStart && copyEnd == fiberEnd)
substringFibers[substringFiberCount++] = UString(fiberString);
else
substringFibers[substringFiberCount++] = UString(StringImpl::create(fiberString, copyStart - fiberStart, copyEnd - copyStart));
if (fiberEnd >= substringEnd)
break;
if (fiberCount > substringFromRopeCutoff || substringFiberCount >= 3) {
// This turned out to be a really inefficient rope. Just flatten it.
resolveRope(exec);
return jsSubstring(&exec->globalData(), m_value, substringStart, substringLength);
}
}
ASSERT(substringFiberCount && substringFiberCount <= 3);
if (substringLength == 1) {
ASSERT(substringFiberCount == 1);
UChar c = substringFibers[0].characters()[0];
if (c <= maxSingleCharacterString)
return globalData->smallStrings.singleCharacterString(globalData, c);
}
if (substringFiberCount == 1)
return new (globalData) TiString(globalData, substringFibers[0]);
if (substringFiberCount == 2)
return new (globalData) TiString(globalData, substringFibers[0], substringFibers[1]);
return new (globalData) TiString(globalData, substringFibers[0], substringFibers[1], substringFibers[2]);
}