content: package act.plugin;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 ActFramework
   * %%
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   * #L%
   */
  
  import org.osgl.util.C;
  
  import java.util.List;
  import java.util.Set;
  
  /**
   * Tag a class that could be plug into Act stack
   */
  public interface Plugin {
      void register();
  
      class InfoRepo {
  
          private static Set<String> plugins = C.newSet();
  
          public static synchronized void register(Plugin plugin) {
              boolean added = plugins.add(plugin.getClass().getName());
              if (added) {
                  plugin.register();
              }
          }
  
          public static void clear() {
              plugins.clear();
          }
  
          public static List<String> plugins() {
              return C.list(plugins);
          }
      }
  }
  