Method locateFrameRange

src/jrd/recsrc/WindowedStream.cpp:985–1096

}

SINT64 WindowedStream::WindowStream::locateFrameRange(thread_db* tdbb, Request* request, Impure* impure,
	const Frame* frame, const dsc* offsetDesc, SINT64 position) const
{
	if (m_order->expressions.getCount() != 1)
	{
		fb_assert(false);
		return false;
	}

	SINT64 rangePos = position;

	if (offsetDesc)
	{
		cacheValues(tdbb, request, &m_order->expressions, impure->orderValues,
			AdjustFunctor(m_arithNodes[frame == m_frameExtent->frame1 ? 0 : 1], offsetDesc));
	}
	else
	{
		cacheValues(tdbb, request, &m_order->expressions, impure->orderValues,
			DummyAdjustFunctor());
	}

	// We found a NULL...
	if (!impure->orderValues[0].vlu_desc.dsc_address)
	{
		if (frame == m_frameExtent->frame2)
		{
			while (++rangePos <= impure->partitionBlock.endPosition)
			{
				if (!m_next->getRecord(tdbb))
					fb_assert(false);

				if (lookForChange(tdbb, request, &m_order->expressions, m_order,
						impure->orderValues))
				{
					break;
				}
			}

			--rangePos;
		}
	}
	else if (frame->bound == Frame::Bound::FOLLOWING)
	{
		const int bound = frame == m_frameExtent->frame1 ? 0 : 1;

		do
		{
			if (lookForChange(tdbb, request, &m_order->expressions, m_order, impure->orderValues) >=
					bound ||
				++rangePos > impure->partitionBlock.endPosition)
			{
				break;
			}

			if (!m_next->getRecord(tdbb))
				fb_assert(false);
		} while (true);