KumiScript/interpreter/expression/ProperListExpression.cs

namespace KumiScript.Interpreter
{
    public class ProperListExpression : ListExpression
    {
        readonly List<Expression> _values;
        public ProperListExpression(List<Expression> expressions)
        {
            _values = expressions;
        }

        public override Expression Eval(Environment env)
        {
            ProcedureExpression? rator = Car().Eval(env) as ProcedureExpression;
            if (rator is null)
                throw new InterpreterInvalidInvocationException();
            
            ListExpression rand = Cdr();
            return rator.Apply(rand, env);
        }

        public override List<Expression> EvalMembers(Environment env)
        {
            List<Expression> result = new List<Expression>();
            for (int i = 0; i < _values.Count; i++)
                result.Add(_values[i].Eval(env));
            
            return result;
        }

        public override List<Expression> GetMembers()
        {
            return _values;
        }

        public override string ToString()
        {
            return String.Concat("(",
                                 String.Join(' ', (object[]) _values.ToArray()),
                                 ")");
        }

        public override Expression Car()
        {
            if (_values.Count == 0)
                return this;

            return _values.First();
        }

        public override ListExpression Cdr()
        {
            if (_values.Count == 0)
                return this;
             
            List<Expression> rest = new List<Expression>(_values);
            rest.RemoveAt(0);
            return ListFactory.MakeList(rest);
        }

        public override ProperListExpression Cons(Expression expr)
        {
            List<Expression> consd = new List<Expression>(_values);
            consd.Insert(0, expr);
            return new ProperListExpression(consd);
        }

        public override bool Equals(Expression expr)
        {
            ProperListExpression? lexpr = expr as ProperListExpression;
            if (lexpr is null)
                return false;
            
            return lexpr.GetMembers().SequenceEqual(_values);
        }
    }
}