internal double calculateKwdRank(InverseList list, DocumentOccurrences d, int[] occ)
{
int frequency = occ.Length;
int totalNumberOfDocuments = impl.documents.Count;
int nRelevantDocuments = list.Count;
int totalNumberOfWords = impl.inverseIndex.Count;
double idf = System.Math.Log((double)totalNumberOfDocuments / nRelevantDocuments);
double averageWords = (double)totalNumberOfWords / totalNumberOfDocuments;
double density = frequency * System.Math.Log(1 + (DENSITY_MAGIC * averageWords / d.nWordsInDocument));
double wordWeight = (density * idf);
double wordScore = 1;
for (int i = 0; i < frequency; i++)
{
wordScore += wordWeight * occurrenceKindWeight[(uint)occ[i] >> OCC_KIND_OFFSET];
}
return(System.Math.Log(wordScore));
}
internal virtual FullTextQuery optimize(FullTextQuery query)
{
switch (query.op)
{
case FullTextQuery.Operator.And:
case FullTextQuery.Operator.Near:
{
FullTextQuery.Operator op = query.op;
int nConjuncts = 1;
FullTextQuery q = query;
while ((q = ((FullTextQueryBinaryOp)q).right).op == op)
{
nConjuncts += 1;
}
ExpressionWeight[] conjuncts = new ExpressionWeight[nConjuncts + 1];
q = query;
for (int i = 0; i < nConjuncts; i++)
{
FullTextQueryBinaryOp and = (FullTextQueryBinaryOp)q;
conjuncts[i] = new ExpressionWeight();
conjuncts[i].expr = optimize(and.left);
conjuncts[i].weight = calculateWeight(conjuncts[i].expr);
q = and.right;
}
conjuncts[nConjuncts] = new ExpressionWeight();
conjuncts[nConjuncts].expr = optimize(q);
conjuncts[nConjuncts].weight = calculateWeight(conjuncts[nConjuncts].expr);
Array.Sort(conjuncts);
if (op == FullTextQuery.Operator.And)
{
// eliminate duplicates
int n = 0, j = -1;
InverseList list = null;
for (int i = 0; i <= nConjuncts; i++)
{
q = conjuncts[i].expr;
if (q is FullTextQueryMatchOp)
{
FullTextQueryMatchOp match = (FullTextQueryMatchOp)q;
if (n == 0 || kwds[match.wno].list != list)
{
j = match.wno;
list = kwds[j].list;
conjuncts[n++] = conjuncts[i];
}
else
{
kwds[match.wno].sameAs = j;
}
}
else
{
conjuncts[n++] = conjuncts[i];
}
}
nConjuncts = n - 1;
}
else
{
// calculate distance between keywords
int kwdPos = 0;
for (int i = 0; i <= nConjuncts; i++)
{
q = conjuncts[i].expr;
if (q is FullTextQueryMatchOp)
{
FullTextQueryMatchOp match = (FullTextQueryMatchOp)q;
kwds[match.wno].kwdOffset = match.pos - kwdPos;
kwdPos = match.pos;
}
}
}
if (nConjuncts == 0)
{
return(conjuncts[0].expr);
}
else
{
q = query;
int i = 0;
while (true)
{
FullTextQueryBinaryOp and = (FullTextQueryBinaryOp)q;
and.left = conjuncts[i].expr;
if (++i < nConjuncts)
{
q = and.right;
}
else
{
and.right = conjuncts[i].expr;
break;
}
}
}
break;
}
case FullTextQuery.Operator.Or:
{
FullTextQueryBinaryOp or = (FullTextQueryBinaryOp)query;
or.left = optimize(or.left);
or.right = optimize(or.right);
break;
}
case FullTextQuery.Operator.Not:
{
FullTextQueryUnaryOp not = (FullTextQueryUnaryOp)query;
not.opd = optimize(not.opd);
}
break;
default:;
break;
}
return(query);
}
internal InverstListEnumerator(InverseList list, int pos)
{
this.list = list;
this.pos = pos;
Reset();
}
