protected internal virtual FullTextQuery conjunction(QueryScanner scanner)
{
FullTextQuery left = term(scanner);
if (scanner.token == QueryScanner.TKN_WORD || scanner.token == QueryScanner.TKN_AND)
{
if (scanner.token == QueryScanner.TKN_WORD)
{
scanner.unget = true;
}
FullTextQuery.Operator cop = scanner.inQuotes ? FullTextQuery.Operator.Near : FullTextQuery.Operator.And;
FullTextQuery right = disjunction(scanner);
if (left != null && right != null)
{
return(new FullTextQueryBinaryOp(cop, left, right));
}
else if (right != null)
{
return(right);
}
}
return(left);
}
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);
}