xref: /csrg-svn/usr.bin/make/lst.lib/lstIsAtEnd.c (revision 69094)

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * %sccs.include.redist.c%
 */

#ifndef lint
static char sccsid[] = "@(#)lstIsAtEnd.c	8.2 (Berkeley) 04/28/95";
#endif /* not lint */

/*-
 * LstIsAtEnd.c --
 *	Tell if the current node is at the end of the list.
 *	The sequential functions access the list in a slightly different way.
 *	CurPtr points to their idea of the current node in the list and they
 *	access the list based on it. Because the list is circular, Lst_Next
 *	and Lst_Prev will go around the list forever. Lst_IsAtEnd must be
 *	used to determine when to stop.
 */

#include	"lstInt.h"

/*-
 *-----------------------------------------------------------------------
 * Lst_IsAtEnd --
 *	Return true if have reached the end of the given list.
 *
 * Results:
 *	TRUE if at the end of the list (this includes the list not being
 *	open or being invalid) or FALSE if not. We return TRUE if the list
 *	is invalid or unopend so as to cause the caller to exit its loop
 *	asap, the assumption being that the loop is of the form
 *	    while (!Lst_IsAtEnd (l)) {
 *	    	  ...
 *	    }
 *
 * Side Effects:
 *	None.
 *
 *-----------------------------------------------------------------------
 */
Boolean
Lst_IsAtEnd (l)
    Lst	    l;
{
    register List list = (List) l;

    return (!LstValid (l) || !list->isOpen ||
	    (list->atEnd == Head) || (list->atEnd == Tail));
}