private static QueryParserNode BuildTree(IList subtokens, QueryParserNode.Type opCode)
{
QueryParserNode node = new TermNode((string)subtokens[subtokens.Count - 1]);
for (int i = subtokens.Count - 2; i >= 0; i--)
{
TermNode leftOpnd = new TermNode((string)subtokens[i]);
OpNode op = new OpNode(opCode);
op.AddOperand(leftOpnd);
op.AddOperand(node);
node = op;
}
return(node);
}
private static QueryParserNode ParseExpression()
{
QueryParserNode nodeLeftOperand = ProcessTerm();
GetNextToken();
//---------------------------------------------------------------------
// if next token == "" => EOS, no more processing, return left operand
// as result,
// if next token == ")" => we reached the endo of parenthed expression,
// return left operand as result, else process two operands and Op,
// return Op as root.
//---------------------------------------------------------------------
if ((strToken == "") || (strToken == ")") || (strToken == "+\""))
{
BackToken();
return(nodeLeftOperand);
}
QueryParserNode.Type typeNode;
if (!isPhrasalMode)
{
switch (strToken)
{
case "and": typeNode = QueryParserNode.Type.eoAnd; break;
case "or": typeNode = QueryParserNode.Type.eoOr; break;
case "near": typeNode = QueryParserNode.Type.eoNear; break;
default: typeNode = QueryParserNode.Type.eoAnd; BackToken(); break;
}
}
else
{
typeNode = QueryParserNode.Type.eoPhraseNear;
BackToken();
}
OpNode nodeOp = new OpNode(typeNode);
QueryParserNode nodeRightOperand = ParseExpression();
nodeOp.AddOperand(nodeLeftOperand);
nodeOp.AddOperand(nodeRightOperand);
return(nodeOp);
}
