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 */
017package org.apache.bcel.util;
018
019import java.io.ByteArrayInputStream;
020import java.io.DataInputStream;
021
022/**
023 * Utility class that implements a sequence of bytes which can be read via the 'readByte()' method. This is used to
024 * implement a wrapper for the Java byte code stream to gain some more readability.
025 */
026public final class ByteSequence extends DataInputStream {
027
028    private static final class ByteArrayStream extends ByteArrayInputStream {
029
030        ByteArrayStream(final byte[] bytes) {
031            super(bytes);
032        }
033
034        int getPosition() {
035            // pos is protected in ByteArrayInputStream
036            return pos;
037        }
038
039        void unreadByte() {
040            if (pos > 0) {
041                pos--;
042            }
043        }
044    }
045
046    private final ByteArrayStream byteStream;
047
048    public ByteSequence(final byte[] bytes) {
049        super(new ByteArrayStream(bytes));
050        byteStream = (ByteArrayStream) in;
051    }
052
053    public int getIndex() {
054        return byteStream.getPosition();
055    }
056
057    void unreadByte() {
058        byteStream.unreadByte();
059    }
060}