    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 */
    029public final class ByteSequence extends DataInputStream {
    030
    031    private final ByteArrayStream byteStream;
    032
    033
    034    public ByteSequence(final byte[] bytes) {
    035        super(new ByteArrayStream(bytes));
    036        byteStream = (ByteArrayStream) in;
    037    }
    038
    039
    040    public int getIndex() {
    041        return byteStream.getPosition();
    042    }
    043
    044
    045    void unreadByte() {
    046        byteStream.unreadByte();
    047    }
    048
    049    private static final class ByteArrayStream extends ByteArrayInputStream {
    050
    051        ByteArrayStream(final byte[] bytes) {
    052            super(bytes);
    053        }
    054
    055        int getPosition() {
    056            // pos is protected in ByteArrayInputStream
    057            return pos;
    058        }
    059
    060        void unreadByte() {
    061            if (pos > 0) {
    062                pos--;
    063            }
    064        }
    065    }
    066}