    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 $Id$
    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}