package au.gov.amsa.ais.rx;
   
   import java.util.HashMap;
   import java.util.Map;
   
   import rx.functions.Func1;
   
   public class Cache<S, T> {
   
  	private final Func1<S, T> factory;
  
  	public Cache(Func1<S, T> factory) {
  		this.factory = factory;
  	}
  
  	private final Map<S, T> map = new HashMap<S, T>();
  
  	public synchronized Cache<S, T> put(S key, T value) {
  		map.put(key, value);
  		return this;
  	}
  
  	public synchronized T get(S key) {
  		T value = map.get(key);
  		if (value == null) {
  			T t = factory.call(key);
  			map.put(key, t);
  			return t;
  		} else
  			return value;
  	}
  }