Method fetchRelative

src/jrd/recsrc/Cursor.cpp:368–446

}

bool Cursor::fetchRelative(thread_db* tdbb, SINT64 offset) const
{
	if (!m_rse->isScrollable())
	{
		// error: invalid fetch direction
		status_exception::raise(Arg::Gds(isc_invalid_fetch_option) << Arg::Str("RELATIVE"));
	}

	if (!validate(tdbb))
		return false;

	const auto request = tdbb->getRequest();
	Impure* const impure = request->getImpure<Impure>(m_impure);

	if (!impure->irsb_active)
	{
		// error: invalid cursor state
		status_exception::raise(Arg::Gds(isc_cursor_not_open));
	}

	if (!offset)
		return (impure->irsb_state == POSITIONED);

	const auto buffer = static_cast<const BufferedStream*>(m_root);
	const auto count = buffer->getCount(tdbb);
	SINT64 position = impure->irsb_position;

	if (impure->irsb_state == BOS)
	{
		if (offset < 0)
			return false;

		position = offset - 1;
	}
	else if (impure->irsb_state == EOS)
	{
		if (offset > 0)
			return false;

		position = count + offset;
	}
	else
	{
		position += offset;
	}

	if (position < 0)
	{
		impure->irsb_state = BOS;
		return false;
	}
	else if (position >= (SINT64) count)
	{
		impure->irsb_state = EOS;
		return false;
	}

	ProfilerSelectStopWatcher profilerSelectStopWatcher(tdbb, this,