nullinputstream.java

MG4J (Managing Gigabytes for Java) is a free full-text search engine for large document collections

package it.unimi.dsi.mg4j.io;

/*		 
 * MG4J: Managing Gigabytes for Java
 *
 * Copyright (C) 2003-2007 Sebastiano Vigna 
 *
 *  This library is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU Lesser General Public License as published by the Free
 *  Software Foundation; either version 2.1 of the License, or (at your option)
 *  any later version.
 *
 *  This library is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 *  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

import it.unimi.dsi.fastutil.io.MeasurableInputStream;
import it.unimi.dsi.fastutil.io.RepositionableStream;

import java.io.IOException;
import java.io.Serializable;

/** End-of-stream-only input stream.
 *
 * <P>This stream has length 0, and will always return end-of-file on any read attempt.
 *
 * <P>This class is a singleton. You cannot create a null input stream,
 * but you can obtain an instance of this class using {@link #getInstance()}.
 *
 * @author Sebastiano Vigna
 * @since 0.8
 * @deprecated Moved to <code>dsiutils</code>.
 */

@Deprecated
public class NullInputStream extends MeasurableInputStream implements RepositionableStream, Serializable {
	private static final long serialVersionUID = 1L;
	private final static NullInputStream INSTANCE = new NullInputStream();

	private NullInputStream() {}
	 
	public int read() { return -1; }

	/** Returns the only instance of this class.
	 * 
	 * @return  the only instance of this class.
	 */
	public static NullInputStream getInstance() {
		return INSTANCE;
	}

	private Object readResolve() {
		return INSTANCE;
	}

	@Override
	public long length() {
		return 0;
	}

	@Override
	public long position() {
		return 0;
	}

	public void position( long position ) throws IOException {
		// TODO: we should specify the semantics out of bounds
		return;
	}
}