package org.codehaus.plexus.digest;

 /*

  * Copyright 2001-2006 The Codehaus.

  *

  * 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.

  */

 import java.io.InputStream;

 /**

  * Gradually create a digest for a stream.

  *

  * @author <a href="mailto:brett@apache.org">Brett Porter</a>

  */

 public interface StreamingDigester

 {

     String ROLE = StreamingDigester.class.getName();

     /**

      * Get the algorithm used for the checksum.

      *

      * @return the algorithm

      */

     String getAlgorithm();

     /**

      * Reset the hashcode calculation algorithm.

      * Only useful when performing incremental hashcodes based on repeated use of {@link #update(InputStream)}

      *

      * @throws DigesterException if there was a problem with the internal message digest

      */

     void reset()

         throws DigesterException;

     /**

      * Calculate the current checksum.

      *

      * @return the current checksum.

      * @throws DigesterException if there was a problem computing the hashcode.

      */

     String calc()

         throws DigesterException;

     /**

      * Update the checksum with the content of the input stream.

      *

      * @param is the input stream

      * @throws DigesterException if there was a problem computing the hashcode.

      */

     void update( InputStream is )

         throws DigesterException;

 }