code: /*
   * Copyright (C) 2015 Fabrizio Montesi <famontesi@gmail.com>
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   * MA 02110-1301  USA
   */
  package jolie;
  
  import java.util.Map;
  import java.util.concurrent.Callable;
  import java.util.concurrent.ConcurrentHashMap;
  
  /**
   * A utility class for managing shared state across different Jolie extensions.
   * 
   * @author Fabrizio Montesi
   */
  public final class StaticUtils
  {
  	private static final Map< String, Object > m = new ConcurrentHashMap<>();
  
  	public static void create( Class holder, Callable<Object> task )
  	{
  		m.computeIfAbsent( holder.getName(),
  			k -> {
  				try {
  					return task.call();
  				} catch( Exception e ) {
  					throw new RuntimeException( e );
  				}
  			}
  		);
  	}
  	
  	public static <T> T retrieve( Class<?> holder, Class<T> type )
  	{
  		return type.cast( m.get( holder.getName() ) );
  	}
  }
  