bool SymbolCell::operator==(const SymbolCell &other) const
{
if (isGlobalConstant() && other.isGlobalConstant())
{
// Constant folding guarantees this works
return this == &other;
}
if (byteLength() != other.byteLength())
{
return false;
}
if (dataIsInline())
{
auto thisInlineSymbol = static_cast<const InlineSymbolCell*>(this);
auto otherInlineSymbol = static_cast<const InlineSymbolCell*>(&other);
return memcmp(
thisInlineSymbol->inlineData(),
otherInlineSymbol->inlineData(),
thisInlineSymbol->inlineByteLength()) == 0;
}
else
{
auto thisHeapSymbol = static_cast<const HeapSymbolCell*>(this);
auto thisByteArray = thisHeapSymbol->heapByteArray();
auto otherByteArray = static_cast<const HeapSymbolCell*>(&other)->heapByteArray();
return thisByteArray->isEqual(otherByteArray, thisHeapSymbol->heapByteLength());
}
}
bool StringCell::replaceBytes(const CharRange &range, const std::uint8_t *pattern, unsigned int patternBytes, unsigned int count)
{
assert(!isGlobalConstant());
const unsigned int requiredBytes = patternBytes * count;
const unsigned int replacedBytes = range.byteCount();
// If we have exclusive access to our data and we're not resizing the string we can use the fast path
if ((dataIsInline() || static_cast<HeapStringCell*>(this)->heapByteArray()->isExclusive()) &&
(requiredBytes == replacedBytes))
{
std::uint8_t *copyDest = const_cast<std::uint8_t*>(range.startPointer);
while(count--)
{
memmove(copyDest, pattern, patternBytes);
copyDest += patternBytes;
}
}
else
{
// Create a new string from pieces of the old string
const std::uint64_t newByteLength = byteLength() + requiredBytes - replacedBytes;
const auto newCharLength = charLength();
if (newByteLength > maximumByteLength())
{
return false;
}
const ByteLengthType initialBytes = range.startPointer - utf8Data();
const ByteLengthType finalBytes = newByteLength - initialBytes - requiredBytes;
const bool wasInline = dataIsInline();
const bool nowInline = newByteLength <= inlineDataSize();
SharedByteArray *oldByteArray = nullptr;
SharedByteArray *newByteArray = nullptr;
// Does this require a COW due to sharing our byte array?
const bool needsCow = (!wasInline && !nowInline) &&
!static_cast<HeapStringCell*>(this)->heapByteArray()->isExclusive();
// Determine if we exceeded our current capacity or if we're using less than half of our allocated space
// This will trigger a reallocation of our heap space
const auto currentCapacity = byteCapacity();
const bool needHeapRealloc = (newByteLength > currentCapacity) ||
((newByteLength < (currentCapacity / 2)) && !nowInline) ||
needsCow;
std::uint8_t* destString;
const std::uint8_t* copySource;
if (!wasInline && nowInline)
{
// We're converting to an inline string
destString = static_cast<InlineStringCell*>(this)->inlineData();
copySource = pattern;
// Store our old byte array so we can unref it later
// The code below will overwrite it with our new inline string
oldByteArray = static_cast<HeapStringCell*>(this)->heapByteArray();
// Fill the initial chunk of the string
memcpy(destString, utf8Data(), initialBytes);
}
else if (needHeapRealloc)
{
size_t byteArraySize = newByteLength;
newByteArray = SharedByteArray::createInstance(byteArraySize);
destString = newByteArray->data();
copySource = pattern;
// Fill the initial chunk of the string
memcpy(destString, utf8Data(), initialBytes);
if (!wasInline)
{
// Store our old byte array so we can unref it later
oldByteArray = static_cast<HeapStringCell*>(this)->heapByteArray();
}
}
else
{
destString = utf8Data();
// The initial chunk is already correct
// Are our pattern bytes in the range we're about to overwrite?
// We only need to check the end of the pattern because the pattern should only be completely inside our
// completely outside our string
if (((pattern + patternBytes) > (utf8Data() + initialBytes)) &&
((pattern + patternBytes) <= (utf8Data() + byteLength())))
{
// Create a temporary copy to work with
copySource = new std::uint8_t[patternBytes];
memcpy(const_cast<std::uint8_t*>(copySource), pattern, patternBytes);
}
else
{
copySource = pattern;
}
}
// Move the unchanged chunk at the end
// We need to do this now because if the pattern bytes are longer than the byte we're replacing then we might
// overwrite the beginning of the unchanged chunk
memmove(destString + initialBytes + requiredBytes, range.startPointer + replacedBytes, finalBytes);
std::uint8_t* copyDest = destString + initialBytes;
while(count--)
{
memcpy(copyDest, copySource, patternBytes);
copyDest += patternBytes;
}
if (copySource != pattern)
{
delete[] copySource;
}
// Update ourselves with our new string
setLengths(newByteLength, newCharLength);
if (newByteArray)
{
static_cast<HeapStringCell*>(this)->setHeapByteArray(newByteArray);
}
if (oldByteArray != nullptr)
{
// We can unref this now
oldByteArray->unref();
}
}
return true;
}