package serene.simple;


public class IfSpecialForm extends SpecialForm {

    private Node pred;
    private Node ifNode;
    private Node elseNode;

    public IfSpecialForm(ListNode<Node> l) {
        super(l);
        this.pred = l.rest().first();
        this.ifNode = l.rest().rest().first();
        this.elseNode = l.rest().rest().rest().first();
    }

    @Override
    public Object eval(final Scope scope) {
        Object result = this.pred.eval(scope);
        if (result == null) {
            return this.elseNode.eval(scope);
        }
        return this.ifNode.eval(scope);
    }
}