package it.unimi.dsi.io;
/*
* DSI utilities
*
* Copyright (C) 2003-2009 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
*/
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;
}
}