public ExprNode ParseRelationalExpression()
{
var exp = new RelationalExpression
{
Token = Next(),
LeftExpression = ParseAdditiveExpression(),
};
if (Next().IsNot(TokenType.LessThan) &&
Next().IsNot(TokenType.LessThanOrEqual) &&
Next().IsNot(TokenType.GreaterThan) &&
Next().IsNot(TokenType.GreaterThanOrEqual) &&
Next().IsNot(TokenType.Is))
return exp.LeftExpression;
exp.Operator = Next().Type;
Consume();
exp.RightExpression = ParseRelationalExpression();
return exp;
}