ToNetASCIIOutputStream.java

package ch.cyberduck.core.io;

/*
 * Copyright 2001-2005 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.
 */

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * This class wraps an output stream, replacing all singly occurring
 * <LF> (linefeed) characters with <CR><LF> (carriage return
 * followed by linefeed), which is the NETASCII standard for representing
 * a newline.
 * You would use this class to implement ASCII file transfers requiring
 * conversion to NETASCII.
 * <p/>
 * <p/>
 *
 * @author Daniel F. Savarese
 *         *
 */

public final class ToNetASCIIOutputStream extends FilterOutputStream {
	/**
	 * @uml.property  name="__lastWasCR"
	 */
	private boolean __lastWasCR;

	/**
	 * Creates a ToNetASCIIOutputStream instance that wraps an existing
	 * OutputStream.
	 * <p/>
	 *
	 * @param output The OutputStream to wrap.
	 *               *
	 */
	public ToNetASCIIOutputStream(OutputStream output) {
		super(output);
		__lastWasCR = false;
	}


	/**
	 * Writes a byte to the stream.    Note that a call to this method
	 * may result in multiple writes to the underlying input stream in order
	 * to convert naked newlines to NETASCII line separators.
	 * This is transparent to the programmer and is only mentioned for
	 * completeness.
	 * <p/>
	 *
	 * @param ch The byte to write.
	 * @throws IOException If an error occurs while writing to the underlying
	 *                     stream.
	 *                     *
	 */
	public synchronized void write(int ch)
	    throws IOException {
		switch(ch) {
			case '\r':
				__lastWasCR = true;
				out.write('\r');
				return;
			case '\n':
				if(!__lastWasCR) {
					out.write('\r');
				}
				// Fall through
			default:
				__lastWasCR = false;
				out.write(ch);
				return;
		}
	}


	/**
	 * Writes a byte array to the stream.
	 * <p/>
	 *
	 * @param buffer The byte array to write.
	 * @throws IOException If an error occurs while writing to the underlying
	 *                     stream.
	 *                     *
	 */
	public synchronized void write(byte buffer[])
	    throws IOException {
		write(buffer, 0, buffer.length);
	}


	/**
	 * Writes a number of bytes from a byte array to the stream starting from
	 * a given offset.
	 * <p/>
	 *
	 * @param buffer The byte array to write.
	 * @param offset The offset into the array at which to start copying data.
	 * @param length The number of bytes to write.
	 * @throws IOException If an error occurs while writing to the underlying
	 *                     stream.
	 *                     *
	 */
	public synchronized void write(byte buffer[], int offset, int length)
	    throws IOException {
		while(length-- > 0) {
			write(buffer[offset++]);
		}
	}

}