Agent persistent storage class

persist.agent.nut

class Persist {
    
    cache = null;
    
    // -------------------------------------------------------------------------
    function read(key = null, def = null) {
        if (cache == null) {
            cache = server.load();
        } 
        return (key in cache) ? cache[key] : def;
    }
    
    // -------------------------------------------------------------------------
    function write(key, value) {
        if (cache == null) {
            cache = server.load();
        }
        if (key in cache) {
            server.save(cache);
        } else {
            cache[key] <- value;
            server.save(cache);
        }
        return value;
    }
    
    // -------------------------------------------------------------------------
    function remove(key) {
        if (cache == null) {
            cache = server.load();
        }
        if (key in cache) {
            delete cache[key];
            server.save(cache);
        }
    }
}