KumiScript/reader/ParserQuoteVisitor.cs

using KumiScript.Interpreter;

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

        public Expression VisitAtom(AtomToken atom)
        {
            List<Expression> quotedAtom = new List<Expression>
            {
                new SymbolExpression(SymbolTable.GetInstance().FromString("quote")),
                atom.ToExpression()
            };
            return new ProperListExpression(quotedAtom);
        }

        public Expression VisitEoF(EndOfFileToken eof)
        {
            throw new ParserUnexpectedEndOfFileException("Expected <atom>, <list>, got EOF.");
        }

        public Expression VisitParen(ParenthesisToken paren)
        {
            if (!paren._leftParen)
                throw new ParserUnexpectedTokenException("Unexpected Token ')'!  Wanted <atom>, '('.");
            
            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);
            }
            Expression listExpression = ListFactory.MakeList(list);
            List<Expression> quotedList = new List<Expression>
            {
                new SymbolExpression(SymbolTable.GetInstance().FromString("quote")),
                listExpression
            };
            return new ProperListExpression(quotedList);
        }

        public Expression VisitSpecial(SpecialToken spec)
        {
            throw new ParserUnexpectedTokenException("Expected <atom>, <list>, got SPECIAL.");
        }

        public Expression VisitString(StringToken str)
        {
            List<Expression> quotedString = new List<Expression>
            {
                new SymbolExpression(SymbolTable.GetInstance().FromString("quote")),
                str.ToExpression()
            };
            return new ProperListExpression(quotedString);
        }
    }
}