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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase.codec;
19  
20  import java.io.IOException;
21  import java.io.InputStream;
22  
23  import org.apache.hadoop.hbase.Cell;
24  
25  public abstract class BaseDecoder implements Codec.Decoder {
26    protected final InputStream in;
27    private boolean hasNext = true;
28    private Cell current = null;
29  
30    public BaseDecoder(final InputStream in) {
31      this.in = in;
32    }
33  
34    @Override
35    public boolean advance() {
36      if (!this.hasNext) return this.hasNext;
37      try {
38        if (this.in.available() <= 0) {
39          this.hasNext = false;
40          return this.hasNext;
41        }
42        this.current = parseCell();
43      } catch (IOException e) {
44        throw new RuntimeException(e);
45      }
46      return this.hasNext;
47    }
48  
49    /**
50     * @return extract a Cell
51     * @throws IOException
52     */
53    protected abstract Cell parseCell() throws IOException;
54  
55    @Override
56    public Cell current() {
57      return this.current;
58    }
59  }