/*
 * Copyright  2000-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); 
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License. 
 *
 */
package org.apache.bcel.util;

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;

/**
 * Utility class that implements a sequence of bytes which can be read via the
 * `readByte()' method. This is used to implement a wrapper for the Java byte
 * code stream to gain some more readability.
 * 
 * @version $Id: ByteSequence.java 386056 2006-03-15 11:31:56Z tcurdt $
 * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
 */
public final class ByteSequence extends DataInputStream {

	private ByteArrayStream byte_stream;

	public ByteSequence(byte[] bytes) {
		super(new ByteArrayStream(bytes));
		byte_stream = (ByteArrayStream) in;
	}

	public final int getIndex() {
		return byte_stream.getPosition();
	}

	final void unreadByte() {
		byte_stream.unreadByte();
	}

	private static final class ByteArrayStream extends ByteArrayInputStream {

		ByteArrayStream(byte[] bytes) {
			super(bytes);
		}

		final int getPosition() {
			return pos;
		} // is protected in ByteArrayInputStream

		final void unreadByte() {
			if (pos > 0) {
				pos--;
			}
		}
	}
}
