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  * @version $Id$
29  */
30 public final class ByteSequence extends DataInputStream {
31 
32     private final ByteArrayStream byteStream;
33 
34 
ByteSequence(final byte[] bytes)35     public ByteSequence(final byte[] bytes) {
36         super(new ByteArrayStream(bytes));
37         byteStream = (ByteArrayStream) in;
38     }
39 
40 
getIndex()41     public final int getIndex() {
42         return byteStream.getPosition();
43     }
44 
45 
unreadByte()46     final void unreadByte() {
47         byteStream.unreadByte();
48     }
49 
50     private static final class ByteArrayStream extends ByteArrayInputStream {
51 
ByteArrayStream(final byte[] bytes)52         ByteArrayStream(final byte[] bytes) {
53             super(bytes);
54         }
55 
getPosition()56         final int getPosition() {
57             // pos is protected in ByteArrayInputStream
58             return pos;
59         }
60 
unreadByte()61         final void unreadByte() {
62             if (pos > 0) {
63                 pos--;
64             }
65         }
66     }
67 }
68