private IEnumerable <DocumentId> ExecuteAnd(BooleanQueryOperationAnd opAnd)
{
var minHeapComparer = Comparer <IEnumerator <DocumentId> > .Create((x, y)
=> y.Current.CompareTo(x.Current));
var queue = new PriorityQueue <IEnumerator <DocumentId> >(
opAnd.Elements.Count,
minHeapComparer);
foreach (var q in opAnd.Elements)
{
var enumerator = ExecuteQuery(q).GetEnumerator();
if (enumerator.MoveNext())
{
queue.Push(enumerator);
}
else
{
yield break;
}
}
DocumentId prev = new DocumentId(0);
int counter = 0;
while (queue.Count > 0)
{
var enumerator = queue.Pop();
if (prev.CompareTo(enumerator.Current) == 0)
{
counter++;
if (counter == opAnd.Elements.Count)
{
yield return(prev);
}
}
else if (queue.Count < opAnd.Elements.Count - 1)
{
yield break;
}
else
{
prev = enumerator.Current;
counter = 1;
if (counter == opAnd.Elements.Count)
{
yield return(prev);
}
}
if (enumerator.MoveNext())
{
queue.Push(enumerator);
}
}
}
private IEnumerable <DocumentId> ExecuteOr(BooleanQueryOperationOr opOr)
{
var minHeapComparer = Comparer <IEnumerator <DocumentId> > .Create((x, y)
=> y.Current.CompareTo(x.Current));
var queue = new PriorityQueue <IEnumerator <DocumentId> >(
opOr.Elements.Count,
minHeapComparer);
foreach (var q in opOr.Elements)
{
var enumerator = ExecuteQuery(q).GetEnumerator();
if (enumerator.MoveNext())
{
queue.Push(enumerator);
}
}
DocumentId?prev = null;
while (queue.Count > 0)
{
var enumerator = queue.Pop();
DocumentId current = enumerator.Current;
if (enumerator.MoveNext())
{
queue.Push(enumerator);
}
if ((prev?.CompareTo(current) ?? -1) != 0)
{
yield return(current);
}
prev = current;
}
}
