namespace KumiScript.Interpreter
{
    public class Expression
    {
        public virtual Expression Eval(Environment env)
        {
            return this;
        }

        public virtual decimal GetValueAsFloat()
        {
            throw new InterpreterTypingException();
        }

        public virtual Expression Car()
        {
            throw new InterpreterTypingException();
        }

        public virtual Expression Cdr()
        {
            throw new InterpreterTypingException();
        }

        public virtual ProperListExpression Cons(Expression expr)
        {
            throw new InterpreterTypingException();
        }

        public virtual ProperListExpression AppendToList(Expression expr)
        {
            List<Expression> el = new List<Expression>(2)
            {
                this,
                expr
            };
            return new ProperListExpression(el);
        }

        public virtual List<Expression> EvalMembers(Environment env)
        {
            throw new InterpreterTypingException();
        }

        public virtual List<Expression> GetMembers()
        {
            throw new InterpreterTypingException();
        }

        public virtual Symbol GetSymbol()
        {
            throw new InterpreterTypingException();
        }

        public virtual Expression Apply(Expression operand, Environment env)
        {
            throw new InterpreterTypingException();
        }

        public virtual bool IsPrimitive()
        {
            throw new InterpreterTypingException();
        }

        public virtual bool Equals (Expression expr)
        {
            return ReferenceEquals(this, expr);
        }
    }
}