private static final Pattern VARIABLE = Pattern.compile("[$][{]([a-zA-Z0-9_/]+)[}]");
    
    public String expand(String s) {
        String s2 = s;
        String v = null;
        Matcher m = VARIABLE.matcher(s);
        while( m.find() ) {
            String name = m.group(1);
            String[] ss = name.split("/");
            switch( ss.length) {
            case 2:
                v = getValue(ss[0],ss[1]);
                break;
            case 1:
                v = getValue(ss[0]);
                break;
            default:
                v = name;
            } 
            s2 = m.replaceFirst(v);
            m = VARIABLE.matcher(s2);
        }
        
        return s2;
    }
    
    public String getValue(String optionName) {
        return "value of "+optionName;
    }

    public String getValue(String sectionName, String optionName) {
        return "value of "+sectionName+":"+optionName;
    }