public override bool TryGetValue(THashKey key, ref HashLookupValueList <IEnumerable <TElement>, TOrderKey> value)
{
Pair <IEnumerable <TElement>, TOrderKey> valueList = GetValueList(key);
value = new HashLookupValueList <IEnumerable <TElement>, TOrderKey>(valueList.First, valueList.Second);
return(true);
}
public bool Add(THashKey hashKey, TElement element, TOrderKey orderKey)
{
HashLookupValueList <TElement, TOrderKey> currentValue = default(HashLookupValueList <TElement, TOrderKey>);
if (!_base.TryGetValue(hashKey, ref currentValue))
{
currentValue = new HashLookupValueList <TElement, TOrderKey>(element, orderKey);
_base.Add(hashKey, currentValue);
return(false);
}
else
{
if (currentValue.Add(element, orderKey))
{
// We need to re-store this element because the pair is a value type.
_base[hashKey] = currentValue;
}
return(true);
}
}
//---------------------------------------------------------------------------------------
// MoveNext implements all the hash-join logic noted earlier. When it is called first, it
// will execute the entire inner query tree, and build a hash-table lookup. This is the
// Building phase. Then for the first call and all subsequent calls to MoveNext, we will
// incrementally perform the Probing phase. We'll keep getting elements from the outer
// data source, looking into the hash-table we built, and enumerating the full results.
//
// This routine supports both inner and outer (group) joins. An outer join will yield a
// (possibly empty) list of matching elements from the inner instead of one-at-a-time,
// as we do for inner joins.
//
internal override bool MoveNext(ref TOutput currentElement, ref TOutputKey currentKey)
{
Debug.Assert(_resultSelector != null, "expected a compiled result selector");
Debug.Assert(_leftSource != null);
Debug.Assert(_rightLookupBuilder != null);
// BUILD phase: If we haven't built the hash-table yet, create that first.
Mutables mutables = _mutables;
if (mutables == null)
{
mutables = _mutables = new Mutables();
mutables._rightHashLookup = _rightLookupBuilder.BuildHashLookup(_cancellationToken);
}
// PROBE phase: So long as the source has a next element, return the match.
ListChunk <Pair <TRightInput, TRightKey> > currentRightChunk = mutables._currentRightMatches;
if (currentRightChunk != null && mutables._currentRightMatchesIndex == currentRightChunk.Count)
{
mutables._currentRightMatches = currentRightChunk.Next;
mutables._currentRightMatchesIndex = 0;
}
if (mutables._currentRightMatches == null)
{
// We have to look up the next list of matches in the hash-table.
Pair <TLeftInput, THashKey> leftPair = default(Pair <TLeftInput, THashKey>);
TLeftKey leftKey = default(TLeftKey);
while (_leftSource.MoveNext(ref leftPair, ref leftKey))
{
if ((mutables._outputLoopCount++ & CancellationState.POLL_INTERVAL) == 0)
{
CancellationState.ThrowIfCanceled(_cancellationToken);
}
// Find the match in the hash table.
HashLookupValueList <TRightInput, TRightKey> matchValue = default(HashLookupValueList <TRightInput, TRightKey>);
TLeftInput leftElement = leftPair.First;
THashKey leftHashKey = leftPair.Second;
// Ignore null keys.
if (leftHashKey != null)
{
if (mutables._rightHashLookup.TryGetValue(leftHashKey, ref matchValue))
{
// We found a new match. We remember the list in case there are multiple
// values under this same key -- the next iteration will pick them up.
mutables._currentRightMatches = matchValue.Tail;
Debug.Assert(mutables._currentRightMatches == null || mutables._currentRightMatches.Count > 0,
"we were expecting that the list would be either null or empty");
mutables._currentRightMatchesIndex = 0;
// Yield the value.
currentElement = _resultSelector(leftElement, matchValue.Head.First);
currentKey = _outputKeyBuilder.Combine(leftKey, matchValue.Head.Second);
// If there is a list of matches, remember the left values for next time.
if (matchValue.Tail != null)
{
mutables._currentLeft = leftElement;
mutables._currentLeftKey = leftKey;
}
return(true);
}
}
}
// If we've reached the end of the data source, we're done.
return(false);
}
// Produce the next element.
Debug.Assert(mutables._currentRightMatches != null);
Debug.Assert(0 <= mutables._currentRightMatchesIndex && mutables._currentRightMatchesIndex < mutables._currentRightMatches.Count);
Pair <TRightInput, TRightKey> rightMatch = mutables._currentRightMatches._chunk[mutables._currentRightMatchesIndex];
currentElement = _resultSelector(mutables._currentLeft, rightMatch.First);
currentKey = _outputKeyBuilder.Combine(mutables._currentLeftKey, rightMatch.Second);
mutables._currentRightMatchesIndex++;
return(true);
}
// get the current value if it exists. public abstract bool TryGetValue(THashKey key, ref HashLookupValueList <TElement, TOrderKey> value);
public override bool TryGetValue(THashKey key, ref HashLookupValueList <TElement, TOrderKey> value)
{
return(_base.TryGetValue(key, ref value));
}
