    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}