    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 via the `readByte()' method. This is used to
    025 * implement a wrapper for the Java byte code stream to gain some more readability.
    026 *
    027 */
    028public final class ByteSequence extends DataInputStream {
    029
    030    private static final class ByteArrayStream extends ByteArrayInputStream {
    031
    032        ByteArrayStream(final byte[] bytes) {
    033            super(bytes);
    034        }
    035
    036        int getPosition() {
    037            // pos is protected in ByteArrayInputStream
    038            return pos;
    039        }
    040
    041        void unreadByte() {
    042            if (pos > 0) {
    043                pos--;
    044            }
    045        }
    046    }
    047
    048    private final ByteArrayStream byteStream;
    049
    050    public ByteSequence(final byte[] bytes) {
    051        super(new ByteArrayStream(bytes));
    052        byteStream = (ByteArrayStream) in;
    053    }
    054
    055    public int getIndex() {
    056        return byteStream.getPosition();
    057    }
    058
    059    void unreadByte() {
    060        byteStream.unreadByte();
    061    }
    062}