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 * https://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.bcel.util;
20
21 import java.io.ByteArrayInputStream;
22 import java.io.DataInputStream;
23
24 /**
25 * Utility class that implements a sequence of bytes which can be read via the 'readByte()' method. This is used to
26 * implement a wrapper for the Java byte code stream to gain some more readability.
27 */
28 public final class ByteSequence extends DataInputStream {
29
30 private static final class ByteArrayStream extends ByteArrayInputStream {
31
32 ByteArrayStream(final byte[] bytes) {
33 super(bytes);
34 }
35
36 int getPosition() {
37 // pos is protected in ByteArrayInputStream
38 return pos;
39 }
40
41 void unreadByte() {
42 if (pos > 0) {
43 pos--;
44 }
45 }
46 }
47
48 private final ByteArrayStream byteStream;
49
50 /**
51 * Constructs a ByteSequence.
52 *
53 * @param bytes the byte array.
54 */
55 public ByteSequence(final byte[] bytes) {
56 super(new ByteArrayStream(bytes));
57 byteStream = (ByteArrayStream) in;
58 }
59
60 /**
61 * Gets the current index.
62 *
63 * @return the current index.
64 */
65 public int getIndex() {
66 return byteStream.getPosition();
67 }
68
69 /**
70 * Unreads the last byte.
71 */
72 void unreadByte() {
73 byteStream.unreadByte();
74 }
75 }