protected virtual bool TryGetFilteredFullKeys(int position, T subKey, ISet <K> source, out HashSet <K> target)
{
if (source.Count == 0)
{
target = default(HashSet <K>);
return(false);
}
target = new HashSet <K>(EqualityComparerExtensions.ReferenceEqualityComparerOf <K>());
foreach (K fullKey in source)
{
if (SubKeyComparer.Equals(subKey, fullKey.ElementAtOrDefault(position)))
{
target.Add(fullKey);
}
}
if (target.Count == 0)
{
target = default(HashSet <K>);
return(false);
}
return(true);
}
public override bool TryGetFullKeysByPartialKey(IEnumerable <T> subKeys, IEnumerable <int> positions, out IEnumerable <K> fullKeys)
{
if (subKeys == null)
{
throw new ArgumentNullException("subKeys");
}
if (positions == null)
{
throw new ArgumentNullException("positions");
}
if (!subKeys.Any())
{
fullKeys = default(IEnumerable <K>);
return(false);
}
IList <int> positionList = positions as IList <int> ?? positions.ToList();
IList <T> subKeyList = subKeys as IList <T> ?? subKeys.ToList();
IList <ISet <K> > subResults = new List <ISet <K> >();
int minSize = int.MaxValue;
int minPos = -1;
foreach (var subKey in subKeyList)
{
if (!partMap.TryGetValue(subKey, out ISet <K> subResult))
{
fullKeys = default(IEnumerable <K>);
return(false);
}
if (subResult.Count < minSize)
{
minSize = subResult.Count;
minPos = subResults.Count;
}
subResults.Add(subResult);
}
if (subResults.Count == 0)
{
fullKeys = default(IEnumerable <K>);
return(false);
}
HashSet <K> result;
if (GetAtOrNegative(positionList, minPos) < 0)
{
result = new HashSet <K>(subResults[minPos], EqualityComparerExtensions.ReferenceEqualityComparerOf <K>());
}
else if (!TryGetFilteredFullKeys(GetAtOrNegative(positionList, minPos), subKeyList[minPos], subResults[minPos], out result))
{
fullKeys = default(IEnumerable <K>);
return(false);
}
if (subResults.Count == 1)
{
fullKeys = result;
return(true);
}
for (int i = 0; i < subResults.Count; i++)
{
if (i != minPos)
{
result.IntersectWith(subResults[i]);
if (result.Count == 0)
{
fullKeys = default(ISet <K>);
return(false);
}
}
}
var subKeyPosList = subKeyList
.Zip <T, int, (T subKey, int position)>(positionList, (subKey, position) => (subKey, position))
.Where((tuple, index) => (index != minPos) && (tuple.position > 0))
.ToList();
if (subKeyPosList.Count != 0)
{
// could be streamed via IEnumerable result.Where(<the predicate opposite the one below>) but then subKeyList and positionList should always be copied
result.RemoveWhere(key =>
{
foreach (var subKeyPos in subKeyPosList)
{
if (!SubKeyComparer.Equals(subKeyPos.subKey, key.ElementAtOrDefault(subKeyPos.position)))
{
return(true);
}
}
return(false);
});
if (result.Count == 0)
{
fullKeys = default(IEnumerable <K>);
return(false);
}
}
fullKeys = result;
return(true);
}