content: /*******************************************************************************
   * Copyright 2014 Trevor Robinson
   * 
   * 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.
   ******************************************************************************/
  package com.scurrilous.circe.crc;
  
  import java.util.zip.CRC32;
  import com.scurrilous.circe.StatefulHash;
  import com.scurrilous.circe.StatefulIntHash;
  import com.scurrilous.circe.StatelessIntHash;
  import com.scurrilous.circe.impl.AbstractStatefulHash;
  import com.scurrilous.circe.impl.AbstractStatelessIntHash;
  import com.scurrilous.circe.params.CrcParameters;
  
  /**
   * Wraps {@link CRC32} in a {@link StatefulIntHash}.
   */
  final class JavaCrc32 extends AbstractStatefulHash implements StatefulIntHash {
  
      private static final String ALGORITHM = CrcParameters.CRC32.algorithm();
      private static final int LENGTH = 4;
  
      private final CRC32 impl = new CRC32();
  
      @Override
      public String algorithm() {
          return ALGORITHM;
      }
  
      @Override
      public int length() {
          return LENGTH;
      }
  
      @Override
      public StatefulHash createNew() {
          return new JavaCrc32();
      }
  
      @Override
      public boolean supportsIncremental() {
          return true;
      }
  
      @Override
      public void reset() {
          impl.reset();
      }
  
      @Override
      protected void updateUnchecked(byte[] input, int index, int length) {
          impl.update(input, index, length);
      }
  
      @Override
      public int getInt() {
          return (int) impl.getValue();
      }
  
      @Override
      public long getLong() {
          return impl.getValue();
      }
  
      @Override
      public StatelessIntHash asStateless() {
          return new AbstractStatelessIntHash() {
              @Override
              public String algorithm() {
                  return ALGORITHM;
              }
  
              @Override
              public int length() {
                  return LENGTH;
              }
  
              @Override
              public StatefulIntHash createStateful() {
                  return new JavaCrc32();
              }
  
              @Override
              protected int calculateUnchecked(byte[] input, int index, int length) {
                  final CRC32 crc32 = new CRC32();
                  crc32.update(input, index, length);
                  return (int) crc32.getValue();
              }
          };
      }
  }
  