//==============================================================================
// NullInputStream.java
//==============================================================================

package tribble.io;


// System imports

import java.io.InputStream;
import java.io.IOException;

import java.lang.String;


// Local imports

// (None)


/*******************************************************************************
* Null input stream.
*
* <p>
* A stream which contains no data, i.e., it always returns end-of-file when
* attempts are made to read from it.  This is similar to the Unix/POSIX
* <tt>/dev/null</tt> device or the MS-DOS <tt>nul</tt> file.
*
* <p>
* Note that none of the methods throw an <tt>IOException</tt>.
*
* <!-- --------------------------------------------------------------------- -->
* @version	$Revision: 1.2 $ $Date: 2005/04/06 03:31:02 $
* @since	2005-04-05
* @author
*	David R. Tribble
*	(<a href="mailto:david@tribble.com">david@tribble.com</a>).
*	<br>
*
*	Copyright ©2005 by David R. Tribble, all rights reserved.
*	<br>
*	Permission is granted to freely use and distribute this source
*	code provided that the original copyright and authorship notices
*	remain intact.
*
* @see	NullOutputStream
*/

public class NullInputStream
    extends java.io.InputStream
{
// Identification

    /** Revision information. */
    static final String		REV =
        "@(#)tribble/io/NullInputStream.java $Revision: 1.2 $ $Date: 2005/04/06 03:31:02 $\n";


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Public static variables

    /** A null input stream. */
    public static NullInputStream	NULL_IN =
        new NullInputStream();


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Public constructors

    /***************************************************************************
    * Default constructor.
    *
    * @since	1.1, 2005-04-05
    */

    public NullInputStream()
    {
        // Initialize
    }


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Public methods

    /***************************************************************************
    * Read a byte from this (empty) stream.
    *
    * <p>
    * Note that this method never throws an <tt>IOException</tt>.
    *
    * @return
    * -1 always, indication no more input is available.
    *
    * @since	1.1, 2005-04-05
    */

    public int read()
    {
        // Empty stream
        return (-1);
    }


    /***************************************************************************
    * Read a set of bytes from this (empty) stream.
    *
    * <p>
    * Note that this method never throws an <tt>IOException</tt>.
    *
    * @param	buf
    * An array of bytes to be read.
    * The contents of this are not modified.
    *
    * @return
    * -1 always, indication no more input is available.
    *
    * @since	1.1, 2005-04-05
    */

    public int read(byte[] buf)
    {
        // Empty stream
        return (-1);
    }


    /***************************************************************************
    * Read a set of bytes from this (empty) stream.
    *
    * <p>
    * Note that this method never throws an <tt>IOException</tt>.
    *
    * @param	buf
    * An array of bytes to be read.
    * The contents of this are not modified.
    *
    * @param	off
    * Index of the first byte in <tt>buf</tt> to read.
    *
    * @param	len
    * Number of bytes in <tt>buf</tt> to read.
    * This is ignored.
    *
    * @return
    * -1 always, indication no more input is available.
    *
    * @since	1.1, 2005-04-05
    */

    public int read(byte[] buf, int off, int len)
    {
        // Empty stream
        return (-1);
    }


    /***************************************************************************
    * Skip (discard) a number of bytes from this (empty) stream.
    *
    * <p>
    * Note that this method never throws an <tt>IOException</tt>.
    *
    * @param	n
    * The number of input bytes to skip.
    *
    * @return
    * The number of bytes skipped, which is always <tt>n</tt>.
    *
    * @since	1.1, 2005-04-05
    */

    public long skip(long n)
    {
        // Empty stream
        return (n);
    }
}

// End NullInputStream.java