/// <summary>
/// Compute the union of the provided sets. this method is much faster than
/// computing the union manually since it operates directly at the byte level.
/// </summary>
public static WAH8DocIdSet Union(ICollection <WAH8DocIdSet> docIdSets, int indexInterval)
{
switch (docIdSets.Count)
{
case 0:
return(EMPTY);
case 1:
var iter = docIdSets.GetEnumerator();
iter.MoveNext();
return(iter.Current);
}
// The logic below is very similar to DisjunctionScorer
int numSets = docIdSets.Count;
PriorityQueue <Iterator> iterators = new PriorityQueueAnonymousInnerClassHelper(numSets);
foreach (WAH8DocIdSet set in docIdSets)
{
Iterator iterator = (Iterator)set.GetIterator();
iterator.NextWord();
iterators.Add(iterator);
}
Iterator top = iterators.Top();
if (top.WordNum == int.MaxValue)
{
return(EMPTY);
}
int wordNum = top.WordNum;
byte word = top.Word;
WordBuilder builder = (WordBuilder)(new WordBuilder()).SetIndexInterval(indexInterval);
while (true)
{
top.NextWord();
iterators.UpdateTop();
top = iterators.Top();
if (top.WordNum == wordNum)
{
word |= top.Word;
}
else
{
builder.AddWord(wordNum, word);
if (top.WordNum == int.MaxValue)
{
break;
}
wordNum = top.WordNum;
word = top.Word;
}
}
return(builder.Build());
}
/// <summary>
/// Compute the intersection of the provided sets. this method is much faster than
/// computing the intersection manually since it operates directly at the byte level.
/// </summary>
public static WAH8DocIdSet Intersect(ICollection <WAH8DocIdSet> docIdSets, int indexInterval)
{
switch (docIdSets.Count)
{
case 0:
throw new System.ArgumentException("There must be at least one set to intersect");
case 1:
var iter = docIdSets.GetEnumerator();
iter.MoveNext();
return(iter.Current);
}
// The logic below is similar to ConjunctionScorer
int numSets = docIdSets.Count;
var iterators = new Iterator[numSets];
int i = 0;
foreach (WAH8DocIdSet set in docIdSets)
{
var it = (Iterator)set.GetIterator();
iterators[i++] = it;
}
Array.Sort(iterators, SERIALIZED_LENGTH_COMPARATOR);
WordBuilder builder = (WordBuilder)(new WordBuilder()).SetIndexInterval(indexInterval);
int wordNum = 0;
while (true)
{
// Advance the least costly iterator first
iterators[0].AdvanceWord(wordNum);
wordNum = iterators[0].WordNum;
if (wordNum == DocIdSetIterator.NO_MORE_DOCS)
{
break;
}
byte word = iterators[0].Word;
for (i = 1; i < numSets; ++i)
{
if (iterators[i].WordNum < wordNum)
{
iterators[i].AdvanceWord(wordNum);
}
if (iterators[i].WordNum > wordNum)
{
wordNum = iterators[i].WordNum;
goto mainContinue;
}
Debug.Assert(iterators[i].WordNum == wordNum);
word &= iterators[i].Word;
if (word == 0)
{
// There are common words, but they don't share any bit
++wordNum;
goto mainContinue;
}
}
// Found a common word
Debug.Assert(word != 0);
builder.AddWord(wordNum, word);
++wordNum;
mainContinue :;
}
//mainBreak:
return(builder.Build());
}
