ToNetASCIIInputStream.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.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * This class wraps an input 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 ToNetASCIIInputStream extends FilterInputStream {
	private static final int __NOTHING_SPECIAL = 0;
	private static final int __LAST_WAS_CR = 1;
	private static final int __LAST_WAS_NL = 2;
	/**
	 * @uml.property  name="__status"
	 */
	private int __status;

	/**
	 * Creates a ToNetASCIIInputStream instance that wraps an existing
	 * InputStream.
	 * <p/>
	 *
	 * @param input The InputStream to .
	 *              *
	 */
	public ToNetASCIIInputStream(InputStream input) {
		super(input);
		__status = __NOTHING_SPECIAL;
	}


	/**
	 * Reads and returns the next byte in the stream.  If the end of the
	 * message has been reached, returns -1.
	 * <p/>
	 *
	 * @return The next character in the stream. Returns -1 if the end of the
	 *         stream has been reached.
	 * @throws IOException If an error occurs while reading the underlying
	 *                     stream.
	 *                     *
	 */
	public int read() throws IOException {
		int ch;

		if(__status == __LAST_WAS_NL) {
			__status = __NOTHING_SPECIAL;
			return '\n';
		}

		ch = in.read();

		switch(ch) {
			case '\r':
				__status = __LAST_WAS_CR;
				return '\r';
			case '\n':
				if(__status != __LAST_WAS_CR) {
					__status = __LAST_WAS_NL;
					return '\r';
				}
				// else fall through
			default:
				__status = __NOTHING_SPECIAL;
				return ch;
		}
		// statement not reached
		//return ch;
	}


	/**
	 * Reads the next number of bytes from the stream into an array and
	 * returns the number of bytes read.  Returns -1 if the end of the
	 * stream has been reached.
	 * <p/>
	 *
	 * @param buffer The byte array in which to store the data.
	 * @return The number of bytes read. Returns -1 if the
	 *         end of the message has been reached.
	 * @throws IOException If an error occurs in reading the underlying
	 *                     stream.
	 *                     *
	 */
	public int read(byte buffer[]) throws IOException {
		return read(buffer, 0, buffer.length);
	}


	/**
	 * Reads the next number of bytes from the stream into an array and returns
	 * the number of bytes read.  Returns -1 if the end of the
	 * message has been reached.  The characters are stored in the array
	 * starting from the given offset and up to the length specified.
	 * <p/>
	 *
	 * @param buffer The byte array in which to store the data.
	 * @param offset The offset into the array at which to start storing data.
	 * @param length The number of bytes to read.
	 * @return The number of bytes read. Returns -1 if the
	 *         end of the stream has been reached.
	 * @throws IOException If an error occurs while reading the underlying
	 *                     stream.
	 *                     *
	 */
	public int read(byte buffer[], int offset, int length) throws IOException {
		int ch, off;

		if(length < 1) {
			return 0;
		}

		ch = available();

		if(length > ch) {
			length = ch;
		}

		// If nothing is available, block to read only one character
		if(length < 1) {
			length = 1;
		}

		if((ch = read()) == -1) {
			return -1;
		}

		off = offset;

		do {
			buffer[offset++] = (byte)ch;
		}
		while(--length > 0 && (ch = read()) != -1);

		return (offset-off);
	}

	/**
	 * Returns false.  Mark is not supported. **
	 */
	public boolean markSupported() {
		return false;
	}

	public int available() throws IOException {
		int result;

		result = in.available();

		if(__status == __LAST_WAS_NL) {
			return (result+1);
		}

		return result;
	}
}