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.io;
021
022 import org.apache.james.mime4j.util.ByteArrayBuffer;
023
024 import java.io.FilterInputStream;
025 import java.io.IOException;
026 import java.io.InputStream;
027
028 /**
029 * Input stream capable of reading lines of text.
030 */
031 public abstract class LineReaderInputStream extends FilterInputStream {
032
033 protected LineReaderInputStream(InputStream in) {
034 super(in);
035 }
036
037 /**
038 * Reads one line of text into the given {@link ByteArrayBuffer}.
039 *
040 * @param dst Destination
041 * @return number of bytes copied or <code>-1</code> if the end of
042 * the stream has been reached.
043 *
044 * @throws MaxLineLimitException if the line exceeds a limit on
045 * the line length imposed by a subclass.
046 * @throws IOException in case of an I/O error.
047 */
048 public abstract int readLine(final ByteArrayBuffer dst)
049 throws MaxLineLimitException, IOException;
050
051 /**
052 * Tries to unread the last read line.
053 *
054 * Implementation may refuse to unread a new buffer until the previous
055 * unread one has been competely consumed.
056 *
057 * Implementations will directly use the byte array backed by buf, so
058 * make sure to not alter it anymore once this method has been called.
059 *
060 * @return true if the unread has been succesfull.
061 */
062 public abstract boolean unread(ByteArrayBuffer buf);
063
064 }