KumiScript/reader/ParserTopLevelVisitor.cs

using KumiScript.Interpreter;

namespace KumiScript.Reader
{
    public class ParserTopLevelVisitor : ITokenVisitor
    {
        Parser _parser;
        public ParserTopLevelVisitor(Parser parser)
        {
            _parser = parser;
        }

        public Expression VisitAtom(AtomToken atom)
        {
            return atom.ToExpression();
        }

        public Expression VisitString(StringToken str)
        {
            return str.ToExpression();
        }

        public Expression VisitEoF(EndOfFileToken eof)
        {
            throw new ParserEndOfFileException();
        }

        public Expression VisitParen(ParenthesisToken paren)
        {
            if (!paren._leftParen)
                throw new ParserUnexpectedTokenException("Unexpected Token ')'!  Wanted ATOM, '(', or EOF.");
            
            List<Expression> list = new List<Expression>();
            ParserListVisitor listVisitor = new ParserListVisitor(_parser);
            Expression item = _parser.NextExpressionCC(listVisitor);

            while (!ReferenceEquals(item, FakeExpression.GetInstance()))
            {
                list.Add(item);
                item = _parser.NextExpressionCC(listVisitor);
            }

            return ListFactory.MakeList(list);
        }

        public Expression VisitSpecial(SpecialToken spec)
        {
            if (spec._value == '\'')
                return _parser.NextExpressionCC(new ParserQuoteVisitor(_parser));
                
            throw new NotImplementedException();
        }
    }
}