package com.atlassian.cache.impl;
   
   import com.atlassian.cache.CacheEntryListener;
   
   /**
    * This interface is designed to support {@code Cache} implementations in working with {@code CacheEntryListener}s.
    * <p/>
    * The main usage pattern for which this is designed is to use delegation for add/remove (therefore the listeners are
    * managed by the this interface) and then use notify* methods to create and deliver the actual events.
   */
  public interface CacheEntryListenerSupport<K, V>
  {
      void add(CacheEntryListener<K, V> listener, boolean includeValues);
      void remove(CacheEntryListener<K, V> listener);
  
      void notifyAdd(K key, V value);
      void notifyEvict(K key, V oldValue);
      void notifyRemove(K key, V oldValue);
      void notifyUpdate(K key, V value, V oldValue);
  
      CacheEntryListenerSupport EMPTY = new CacheEntryListenerSupport()
      {
          @Override
          public void add(CacheEntryListener listener, boolean includeValues)
          {
          }
  
          @Override
          public void remove(CacheEntryListener listener)
          {
          }
  
          @Override
          public void notifyAdd(Object key, Object value)
          {
          }
  
          @Override
          public void notifyEvict(Object key, Object oldValue)
          {
          }
  
          @Override
          public void notifyRemove(Object key, Object oldValue)
          {
          }
  
          @Override
          public void notifyUpdate(Object key, Object value, Object oldValue)
          {
          }
      };
  }