/// <summary>
/// Advances iteration.
/// </summary>
/// <returns>False if at end of iteration, true otherwise.</returns>
public override bool MoveNext()
{
if (_leftSource == null) {
_leftSource = new BookmarkableSource();
_rightSource = new LookAheadWrapper();
_leftSource.AddInput(Inputs[0] as InternalRecordSource);
_rightSource.AddInput(Inputs[1] as InternalRecordSource);
}
// start by advancing the left
if (_advanceLeft && !_leftSource.MoveNext()) return false;
int diff = -1;
while (diff < 0) {
bool notDone = true;
if (_advanceRight) notDone = _rightSource.MoveNext();
if (!notDone) {
// diff will not equal zero at this point so we'll join as non-match
_advanceRight = true; // so we continue to find out we're done
break; // so we goto join
}
if (_compareRequired) {
diff = TMSNStoreUtils.Utf8BytesCompare(_leftSource.CurrentRecord.KeyBytes, _rightSource.CurrentRecord.KeyBytes);
}
else diff = 0; // so it looks like we matched
#region MATCH_CODE
if (diff == 0) {
// see notes in InnerJoin. LeftOuterJoin is exactly the same in the match case.
// LNE == T
if (_leftSource.NextRecordEqualsCurrent) {
_advanceLeft = true;
_advanceRight = false;
_compareRequired = false; // no need to compare
// LNE == T, RNE == T
if (_rightSource.NextRecordEqualsCurrent) {
_leftSource.SetBookmark();
}
}
// LNE == F, RNE == T
else if (_rightSource.NextRecordEqualsCurrent) {
_advanceRight = true;
_compareRequired = false; // no need to compare
if (_leftSource.BookmarkExists) {
_leftSource.GoToBookmark();
_advanceLeft = true;
}
else _advanceLeft = false;
}
// LNE == F, RNE == F
else {
_leftSource.ClearBookmark();
_advanceLeft = true;
_advanceRight = true;
_compareRequired = true;
}
break; // go to join code
}
#endregion
else if (diff > 0) { // right side is ahead of left side
_advanceRight = false;
_leftSource.MoveNextHint = _rightSource.CurrentRecord.Key;
}
// diff < 0 (right side is behind left side)
else {
// leave advance left as it is (which is true).
_advanceRight = true;
_rightSource.MoveNextHint = _leftSource.CurrentRecord.Key;
}
}
if (_joiner == null) {
_joiner = new RecordJoiner(_leftSource, _rightSource, _tableColumnSeparator);
}
// joiner knows how to create record if match or if non-match
CurrentRecord = _joiner.Join(_leftSource.CurrentRecord, _rightSource.CurrentRecord, (diff == 0));
return true;
}
/// <summary>
/// Advances Iteration.
/// </summary>
/// <returns>False if at end of iteration, true otherwise.</returns>
public override bool MoveNext()
{
if (_leftSource == null) {
_leftSource = new BookmarkableSource();
_rightSource = new LookAheadWrapper();
_leftSource.AddInput(Inputs[0] as InternalRecordSource);
_rightSource.AddInput(Inputs[1] as InternalRecordSource);
}
int diff = 0; // if we skip compare then diff = 0 for equality
// the top of this loop is always ready to compare the current records
while (true) {
if (_advanceLeft && !_leftSource.MoveNext()) return false;
if (_advanceRight && !_rightSource.MoveNext()) return false;
if (_compareRequired) {
diff = TMSNStoreUtils.Utf8BytesCompare(_leftSource.CurrentRecord.KeyBytes, _rightSource.CurrentRecord.KeyBytes);
}
#region MATCH_CODE
// if there's a match, join the right to the left
if (diff == 0) {
if (_joiner == null) {
_joiner = new RecordJoiner(_leftSource, _rightSource, _tableColumnSeparator);
}
CurrentRecord = _joiner.Join(_leftSource.CurrentRecord, _rightSource.CurrentRecord, true);
// LeftNextEqual RightNextEqual
// A 1 B 2
// M 3 M 4 ==> F F
// X 4 Y 1
// A 1 B 2
// M 3 M 41 ==> F T (advance right)
// X 4 M 2 ==> F F
// Z 1 Y 1
// A 1 B 2
// M 3 M 41 ==> T F (advance left)
// M 4 N 2 ==> F F
// Z 1 Y 1
// A 1 B 2
// M 3 M 41 ==> T T (set left bookmark, advance left)
// M 4 M 2 ==> F T (goto left bookmark, advance left, advance right)
// Z 1 Y 1 ==> T F (advance left)
// ==> F F (advance left, advance right)
// figure out what to advance
// LNE RNE => AdvanceLeft AdvanceRight Note
// F F T T if (bookmarkExists) ClearBookmark();
// F T X T if (bookmarkExists) {gotoBookmark, X=true} else X=false
// T F T F
// T T T F set left bookmark
// LNE == T
if (_leftSource.NextRecordEqualsCurrent) {
_advanceLeft = true;
_advanceRight = false;
_compareRequired = false; // no need to compare
// LNE == T, RNE == T
if (_rightSource.NextRecordEqualsCurrent) {
_leftSource.SetBookmark();
}
}
// LNE == F, RNE == T
else if (_rightSource.NextRecordEqualsCurrent) {
_advanceRight = true;
_compareRequired = false; // no need to compare
if (_leftSource.BookmarkExists) {
_leftSource.GoToBookmark();
_advanceLeft = true;
}
else _advanceLeft = false;
}
// LNE == F, RNE == F
else {
_leftSource.ClearBookmark();
_advanceLeft = true;
_advanceRight = true;
_compareRequired = true;
}
return true;
}
#endregion
else if (diff > 0) {
_advanceLeft = true;
_advanceRight = false;
_leftSource.MoveNextHint = _rightSource.CurrentRecord.Key;
}
else {
_advanceLeft = false;
_advanceRight = true;
_rightSource.MoveNextHint = _leftSource.CurrentRecord.Key;
}
}
}
