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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   *  Unless required by applicable law or agreed to in writing, software
12   *  distributed under the License is distributed on an "AS IS" BASIS,
13   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   *  See the License for the specific language governing permissions and
15   *  limitations under the License.
16   *
17   */
18  package org.apache.bcel.util;
19  
20  import java.io.ByteArrayInputStream;
21  import java.io.DataInputStream;
22  
23  /**
24   * Utility class that implements a sequence of bytes which can be read
25   * via the `readByte()' method. This is used to implement a wrapper for the
26   * Java byte code stream to gain some more readability.
27   *
28   */
29  public final class ByteSequence extends DataInputStream {
30  
31      private final ByteArrayStream byteStream;
32  
33  
34      public ByteSequence(final byte[] bytes) {
35          super(new ByteArrayStream(bytes));
36          byteStream = (ByteArrayStream) in;
37      }
38  
39  
40      public int getIndex() {
41          return byteStream.getPosition();
42      }
43  
44  
45      void unreadByte() {
46          byteStream.unreadByte();
47      }
48  
49      private static final class ByteArrayStream extends ByteArrayInputStream {
50  
51          ByteArrayStream(final byte[] bytes) {
52              super(bytes);
53          }
54  
55          int getPosition() {
56              // pos is protected in ByteArrayInputStream
57              return pos;
58          }
59  
60          void unreadByte() {
61              if (pos > 0) {
62                  pos--;
63              }
64          }
65      }
66  }