package function.builtin.special;

import static function.builtin.EVAL.eval;
import static function.builtin.SET.set;
import static function.builtin.cons.LIST.makeList;

import function.*;
import sexpression.*;

public class SETF extends LispSpecialFunction {

    private ArgumentValidator argumentValidator;

    public SETF() {
        this.argumentValidator = new ArgumentValidator("SETF");
        this.argumentValidator.setExactNumberOfArguments(2);
        this.argumentValidator.setFirstArgumentExpectedType(Symbol.class);
    }

    public SExpression call(Cons argumentList) {
        argumentValidator.validate(argumentList);

        return set(evaluateValueOnly(argumentList));
    }

    private Cons evaluateValueOnly(Cons argumentList) {
        Cons rest = (Cons) argumentList.getRest();
        SExpression value = eval(rest.getFirst());

        return new Cons(argumentList.getFirst(), makeList(value));
    }

}