001    /****************************************************************
002     * Licensed to the Apache Software Foundation (ASF) under one   *
003     * or more contributor license agreements.  See the NOTICE file *
004     * distributed with this work for additional information        *
005     * regarding copyright ownership.  The ASF licenses this file   *
006     * to you under the Apache License, Version 2.0 (the            *
007     * "License"); you may not use this file except in compliance   *
008     * with the License.  You may obtain a copy of the License at   *
009     *                                                              *
010     *   http://www.apache.org/licenses/LICENSE-2.0                 *
011     *                                                              *
012     * Unless required by applicable law or agreed to in writing,   *
013     * software distributed under the License is distributed on an  *
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
015     * KIND, either express or implied.  See the License for the    *
016     * specific language governing permissions and limitations      *
017     * under the License.                                           *
018     ****************************************************************/
019    
020    package org.apache.james.mime4j.util;
021    
022    /**
023     * An immutable sequence of bytes.
024     */
025    public interface ByteSequence {
026    
027        /**
028         * An empty byte sequence.
029         */
030        ByteSequence EMPTY = new EmptyByteSequence();
031    
032        /**
033         * Returns the length of this byte sequence.
034         * 
035         * @return the number of <code>byte</code>s in this sequence.
036         */
037        int length();
038    
039        /**
040         * Returns the <code>byte</code> value at the specified index.
041         * 
042         * @param index
043         *            the index of the <code>byte</code> value to be returned.
044         * @return the corresponding <code>byte</code> value
045         * @throws IndexOutOfBoundsException
046         *             if <code>index < 0 || index >= length()</code>.
047         */
048        byte byteAt(int index);
049    
050        /**
051         * Copies the contents of this byte sequence into a newly allocated byte
052         * array and returns that array.
053         * 
054         * @return a byte array holding a copy of this byte sequence.
055         */
056        byte[] toByteArray();
057    
058    }