package rpn.basic;

import java.util.Hashtable;
import rpn.Calculator;
import rpn.ItemArray;

public class IfItem extends Item {
	
	public IfItem(Calculator ca) {
		super(ca);
		ca.systemInstall(this);
	}
	
	public void exec() {
		if (ca.check(2)) {
			Item b = ca.peek(1);
			Item c = ca.peek(0);
			if (b instanceof BooleanItem 
				&& c instanceof ProcItem) {
				ca.pop(2);
				boolean v = ((BooleanItem) b).v;
				if (v) {
					ItemArray ia = new ItemArray(((ProcItem) c).a);
					ca.pushExec(ia);
				} 
			} else {
				ca.error(this, CalcErr.Type);
			}
		}
		else {
			ca.error(this, CalcErr.Underflow);
		}
	}
	
	public String toString() {
		return("if");
	}
}