package com.atlassian.plugins.rest.common.expand;
   
   import com.atlassian.plugins.rest.common.expand.resolver.EntityExpanderResolver;
   
   /**
    * This is a general-purpose expander for atlassian-rest that delegates the
    * expand process to the entity that is to be expanded (instead of having that
    * knowledge in a separate {@link com.atlassian.plugins.rest.common.expand.EntityExpander}.
    * As a result, this expander can be used for every entity that implements
   * {@link SelfExpanding}.
   *
   * @author Erik van Zijst
   * @since v1.0.7
   */
  public class SelfExpandingExpander extends AbstractRecursiveEntityExpander<SelfExpanding> {
      protected SelfExpanding expandInternal(SelfExpanding selfExpandingObject) {
          selfExpandingObject.expand();
          return selfExpandingObject;
      }
  
      /**
       * To use the self expanding mechanism, make sure you register an instance
       * of this {@link EntityExpanderResolver} in your application's
       * {@link ExpandResponseFilter}.
       */
      public static class Resolver implements EntityExpanderResolver {
          private static final SelfExpandingExpander expander = new SelfExpandingExpander();
  
          public <T> boolean hasExpander(T instance) {
              return hasExpander(instance.getClass());
          }
  
          public boolean hasExpander(Class<?> aClass) {
              return SelfExpanding.class.isAssignableFrom(aClass);
          }
  
          @SuppressWarnings("unchecked")
          public <T> EntityExpander<T> getExpander(T instance) {
              return (EntityExpander<T>) getExpander(instance.getClass());
          }
  
          public <T> EntityExpander<T> getExpander(Class<? extends T> aClass) {
              return hasExpander(aClass) ? (EntityExpander<T>) expander : null;
          }
      }
  }