public abstract void Visit(UnaryExpression expression);
private Expression ParseUnary()
{
if (_current == null)
{
throw new EvaluatorException(_scanner.Column, "Expected unary operator, literal or open bracket.");
}
if (_current.Type == TokenType.Literal)
{
var literal = ParseLiteral();
Consume();
return literal;
}
var unary = new UnaryExpression();
if (_current.Type == TokenType.Minus)
{
unary.Operator = OperatorType.UnaryMinus;
Expect(MiddleGroupUnary);
}
else if (_current.Type == TokenType.Plus)
{
unary.Operator = OperatorType.UnaryPlus;
Expect(MiddleGroupUnary);
}
if (_current.Type == TokenType.Literal)
{
unary.Value = ParseLiteral();
//if (_scanner.PeekToken() != null && _scanner.PeekToken().Type == TokenType.Literal)
//{
// throw new EvaluatorException(_scanner.Column, "Expected expression.");
//}
}
else if (_current.Type == TokenType.LeftParenthesis)
{
unary.Value = ParseExpression();
}
else if (_current.Type == TokenType.Identifier)
{
unary.Value = ParseIdentifier();
}
else
{
throw new EvaluatorException(_scanner.Column, "Expected literal or open bracket.");
}
Consume();
return unary;
}