//>> PrimaryExpr ::= Literal | Number | VariableReference | '(' Expr ')' | FunctionCall
private AstNode ParsePrimaryExpr(AstNode qyInput) {
Debug.Assert(IsPrimaryExpr(this.scanner));
AstNode opnd = null;
switch (this.scanner.Kind) {
case XPathScanner.LexKind.String:
opnd = new Operand(this.scanner.StringValue);
NextLex();
break;
case XPathScanner.LexKind.Number:
opnd = new Operand(this.scanner.NumberValue);
NextLex();
break;
case XPathScanner.LexKind.Dollar:
NextLex();
CheckToken(XPathScanner.LexKind.Name);
opnd = new Variable(this.scanner.Name, this.scanner.Prefix);
NextLex();
break;
case XPathScanner.LexKind.LParens:
NextLex();
opnd = ParseExpresion(qyInput);
if (opnd.TypeOfAst != AstNode.QueryType.ConstantOperand) {
opnd = new Group(opnd);
}
PassToken(XPathScanner.LexKind.RParens);
break;
case XPathScanner.LexKind.Name :
if (this.scanner.CanBeFunction && ! IsNodeType(this.scanner)) {
opnd = ParseMethod(null);
}
break;
}
Debug.Assert(opnd != null, "IsPrimaryExpr() was true. We should recognize this lex.");
return opnd;
}
private static void ComposeVariable(Variable node, StringBuilder expr) {
expr.Append(s_Dollar);
expr.Append(node.Prefix);
expr.Append(":");
expr.Append(node.Localname);
}
private IQuery ProcessVariable(Variable root) {
_hasPrefix = true;
if (! allowVar) {
throw new XPathException(Res.Xp_InvalidKeyPattern, _query);
}
return new VariableQuery(root.Localname, root.Prefix);
}
