Function evlFirstLastDay

src/jrd/SysFunction.cpp:4319–4452

dsc* evlFirstLastDay(thread_db* tdbb, const SysFunction* function, const NestValueArray& args,
	impure_value* impure)
{
	fb_assert(args.getCount() >= 2);

	Request* request = tdbb->getRequest();

	const dsc* partDsc = EVL_expr(tdbb, request, args[0]);
	if (request->req_flags & req_null)	// return NULL if partDsc is NULL
		return NULL;

	const dsc* valueDsc = EVL_expr(tdbb, request, args[1]);
	if (request->req_flags & req_null)	// return NULL if valueDsc is NULL
		return NULL;

	TimeStamp timestamp;
	tm times = {0};
	int fractions = 0;

	switch (valueDsc->dsc_dtype)
	{
		case dtype_sql_date:
			timestamp.value().timestamp_date = *(GDS_DATE*) valueDsc->dsc_address;
			timestamp.value().timestamp_time = 0;
			timestamp.decode(&times, &fractions);
			break;

		case dtype_timestamp:
			timestamp.value() = *(GDS_TIMESTAMP*) valueDsc->dsc_address;
			timestamp.decode(&times, &fractions);
			break;

		case dtype_timestamp_tz:
			TimeZoneUtil::decodeTimeStamp(*(ISC_TIMESTAMP_TZ*) valueDsc->dsc_address, false, TimeZoneUtil::NO_OFFSET,
				&times, &fractions);
			break;

		default:
			status_exception::raise(
				Arg::Gds(isc_expression_eval_err) <<
				Arg::Gds(isc_sysf_invalid_date_timestamp) <<
				Arg::Str(function->name));
			break;
	}

	const SLONG part = MOV_get_long(tdbb, partDsc, 0);

	switch (part)
	{
		case blr_extract_year:
			times.tm_mon = 0;
			// fall through

		case blr_extract_month:
			times.tm_mday = 1;
			break;

		case blr_extract_quarter: