package function.builtin.special;

import static function.builtin.EVAL.eval;

import function.*;
import sexpression.*;

@FunctionNames({ "OR" })
public class OR extends LispSpecialFunction {

    private ArgumentValidator argumentValidator;

    public OR() {
        this.argumentValidator = new ArgumentValidator("OR");
    }

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

        return callTailRecursive(argumentList);
    }

    private SExpression callTailRecursive(Cons argumentList) {
        SExpression currentValue = eval(argumentList.getFirst());
        Cons remainingValues = (Cons) argumentList.getRest();

        if (remainingValues.isNull() || !currentValue.isNull())
            return currentValue;

        return callTailRecursive(remainingValues);
    }

}