001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 *
017 */
018package org.apache.bcel.util;
019
020import java.io.ByteArrayInputStream;
021import java.io.DataInputStream;
022
023/**
024 * Utility class that implements a sequence of bytes which can be read
025 * via the `readByte()' method. This is used to implement a wrapper for the
026 * Java byte code stream to gain some more readability.
027 *
028 * @version $Id: ByteSequence.java 1806200 2017-08-25 16:33:06Z ggregory $
029 */
030public final class ByteSequence extends DataInputStream {
031
032    private final ByteArrayStream byteStream;
033
034
035    public ByteSequence(final byte[] bytes) {
036        super(new ByteArrayStream(bytes));
037        byteStream = (ByteArrayStream) in;
038    }
039
040
041    public final int getIndex() {
042        return byteStream.getPosition();
043    }
044
045
046    final void unreadByte() {
047        byteStream.unreadByte();
048    }
049
050    private static final class ByteArrayStream extends ByteArrayInputStream {
051
052        ByteArrayStream(final byte[] bytes) {
053            super(bytes);
054        }
055
056        final int getPosition() {
057            // pos is protected in ByteArrayInputStream
058            return pos;
059        }
060
061        final void unreadByte() {
062            if (pos > 0) {
063                pos--;
064            }
065        }
066    }
067}