Function evlDateDiff

src/jrd/SysFunction.cpp:4051–4279

dsc* evlDateDiff(thread_db* tdbb, const SysFunction* function, const NestValueArray& args,
	impure_value* impure)
{
	fb_assert(args.getCount() == 3);

	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* value1Dsc = EVL_expr(tdbb, request, args[1]);
	if (request->req_flags & req_null)	// return NULL if value1Dsc is NULL
		return NULL;

	const dsc* value2Dsc = EVL_expr(tdbb, request, args[2]);
	if (request->req_flags & req_null)	// return NULL if value2Dsc is NULL
		return NULL;

	TimeStamp timestamp1;

	switch (value1Dsc->dsc_dtype)
	{
		case dtype_sql_time:
		case dtype_sql_time_tz:
			timestamp1.value().timestamp_time = *(GDS_TIME*) value1Dsc->dsc_address;
			timestamp1.value().timestamp_date = 0;

			if (value1Dsc->dsc_dtype == dtype_sql_time && value2Dsc->isDateTimeTz())
			{
				TimeZoneUtil::localTimeToUtc(timestamp1.value().timestamp_time,
					EngineCallbacks::instance->getSessionTimeZone());
			}
			break;

		case dtype_sql_date:
			timestamp1.value().timestamp_date = *(GDS_DATE*) value1Dsc->dsc_address;
			timestamp1.value().timestamp_time = 0;
			break;

		case dtype_timestamp:
		case dtype_timestamp_tz:
			timestamp1.value() = *(GDS_TIMESTAMP*) value1Dsc->dsc_address;

			if (value1Dsc->dsc_dtype == dtype_timestamp && value2Dsc->isDateTimeTz())
				TimeZoneUtil::localTimeStampToUtc(timestamp1.value(), &EngineCallbacks::instance);
			break;

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

	TimeStamp timestamp2;

	switch (value2Dsc->dsc_dtype)