Function makeOverlay

src/jrd/SysFunction.cpp:1682–1717

void makeOverlay(DataTypeUtilBase* dataTypeUtil, const SysFunction* function, dsc* result,
	int argsCount, const dsc** args)
{
	fb_assert(argsCount >= function->minArgCount);

	result->makeNullString();

	bool isNullable;
	if (initResult(result, argsCount, args, &isNullable))
		return;

	const dsc* value = args[0];
	const dsc* placing = args[1];

	if (value->isBlob())
		*result = *value;
	else if (placing->isBlob())
		*result = *placing;
	else
	{
		result->clear();
		result->dsc_dtype = dtype_varying;
	}

	result->setBlobSubType(dataTypeUtil->getResultBlobSubType(value, placing));
	result->setTextType(dataTypeUtil->getResultTextType(value, placing));

	if (!value->isBlob() && !placing->isBlob())
	{
		result->dsc_length = static_cast<USHORT>(sizeof(USHORT)) +
			dataTypeUtil->convertLength(value, result) +
			dataTypeUtil->convertLength(placing, result);
	}

	result->setNullable(isNullable);
}


void makePad(DataTypeUtilBase* dataTypeUtil, const SysFunction* function, dsc* result,