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 package org.apidesign.impl.security.spi;

 import org.apidesign.impl.security.friendapi.DigestImplementation;

 import org.apidesign.impl.security.friendapi.DigestProvider;

 import java.nio.ByteBuffer;

 import java.util.ServiceLoader;

 import org.apidesign.spi.security.Digestor;

 /**

  *

  * @author Jaroslav Tulach

  */

 public class DigestorProvider implements DigestProvider {

     public DigestImplementation create(String algorithm) {

         for (Digestor<?> d : ServiceLoader.load(Digestor.class)) {

             Handler<?> h = create(d, algorithm);

             if (h != null) {

                 return h;

             }

         }

         return null;

     }

     private static <Data> Handler<Data> create(Digestor<Data> dig, String algorithm) {

         Data d = DigestorAccessor.getDefault().create(dig, algorithm);

         if (d == null) {

             return null;

         } else {

             return new Handler<Data>(algorithm, dig, d);

         }

     }

     private static final class Handler<Data> extends DigestImplementation {

         private final Digestor dig;

         private final Data data;

         public Handler(String algorithm, Digestor dig, Data data) {

             super(algorithm);

             this.dig = dig;

             this.data = data;

         }

         @Override

         public void update(ByteBuffer bb) {

             DigestorAccessor.getDefault().update(dig, data, bb);

         }

         @Override

         public byte[] digest() {

             return DigestorAccessor.getDefault().digest(dig, data);

         }

     }

 }