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/*
 * #%L
 * *********************************************************************************************************************
 *
 * These Foolish Things - Miscellaneous utilities
 * http://thesefoolishthings.java.net - hg clone https://bitbucket.org/tidalwave/thesefoolishthings-src
 * %%
 * Copyright (C) 2009 - 2013 Tidalwave s.a.s. (http://tidalwave.it)
 * %%
 * *********************************************************************************************************************
 *
 * 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.
 *
 * *********************************************************************************************************************
 *
 * $Id$
 *
 * *********************************************************************************************************************
 * #L%
 */
package it.tidalwave.util.spi;

import javax.annotation.Nonnull;
import java.util.Iterator;
import java.util.ServiceLoader;
import lombok.AccessLevel;
import lombok.NoArgsConstructor;

/***********************************************************************************************************************
 *
 * @author  Fabrizio Giudici
 * @version $Id$
 *
 **********************************************************************************************************************/
public interface AsDelegateProvider
  {
    public static final Class AsDelegateProvider = AsDelegateProvider.class;

    @NoArgsConstructor(access = AccessLevel.PRIVATE)
    public static final class Locator
      {
        private static AsDelegateProvider asSpiProvider;

        @Nonnull
        public static synchronized AsDelegateProvider find()
          {
            if (asSpiProvider == null)
              {
                final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
                final Iterator i =
                        ServiceLoader.load(AsDelegateProvider.class, classLoader).iterator();

                if (!i.hasNext())
                  {
                    throw new RuntimeException("No ServiceProvider for AsDelegateProvider");
                  }

                asSpiProvider = i.next();
              }

            return asSpiProvider;
          }

        /** For testing */
        public static void set (final @Nonnull AsDelegateProvider provider)
          {
            asSpiProvider = provider;
          }
      }

    /*******************************************************************************************************************
     *
     *
     ******************************************************************************************************************/
    @Nonnull
    public AsDelegate createAsDelegate (@Nonnull Object datum);
  }