/*	$Id: QLink.h,v 1.2 1999/06/13 07:41:04 robert Exp $ */
/*
 * Copyright (c) 1990-1996 Sam Leffler
 * Copyright (c) 1991-1996 Silicon Graphics, Inc.
 * HylaFAX is a trademark of Silicon Graphics
 *
 * Permission to use, copy, modify, distribute, and sell this software and 
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 * 
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 * 
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 * OF THIS SOFTWARE.
 */
#ifndef _QLink_
#define	_QLink_
/*
 * Doubly-linked list used in queues.
 */
struct QLink {
    QLink*	next;		// forward link
    QLink*	prev;		// backward link

    QLink();
    QLink(const QLink& other);
    virtual ~QLink();

    void remove(void);
    void insert(QLink& after);

    int isEmpty(void) const;		// true if list is empty (used on head)
    int isOnList(void) const;		// true if item is on list
};
inline int QLink::isEmpty(void) const	{ return next == this; }
inline int QLink::isOnList(void) const	{ return next != this; }
#endif /* _QLink_ */
