usr.bin/make/lst.lib/lstIsAtEnd.c

   1 /*      $NetBSD: lstIsAtEnd.c,v 1.13 2008/02/15 21:29:50 christos Exp $ */
   2
   3 /*
   4  * Copyright (c) 1988, 1989, 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Adam de Boor.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #ifndef MAKE_NATIVE
  36 static char rcsid[] = "$NetBSD: lstIsAtEnd.c,v 1.13 2008/02/15 21:29:50 christos Exp $";
  37 #else
  38 #include <sys/cdefs.h>
  39 #ifndef lint
  40 #if 0
  41 static char sccsid[] = "@(#)lstIsAtEnd.c        8.1 (Berkeley) 6/6/93";
  42 #else
  43 __RCSID("$NetBSD: lstIsAtEnd.c,v 1.13 2008/02/15 21:29:50 christos Exp $");
  44 #endif
  45 #endif /* not lint */
  46 #endif
  47
  48 /*-
  49  * LstIsAtEnd.c --
  50  *      Tell if the current node is at the end of the list.
  51  *      The sequential functions access the list in a slightly different way.
  52  *      CurPtr points to their idea of the current node in the list and they
  53  *      access the list based on it. Because the list is circular, Lst_Next
  54  *      and Lst_Prev will go around the list forever. Lst_IsAtEnd must be
  55  *      used to determine when to stop.
  56  */
  57
  58 #include        "lstInt.h"
  59
  60 /*-
  61  *-----------------------------------------------------------------------
  62  * Lst_IsAtEnd --
  63  *      Return true if have reached the end of the given list.
  64  *
  65  * Results:
  66  *      TRUE if at the end of the list (this includes the list not being
  67  *      open or being invalid) or FALSE if not. We return TRUE if the list
  68  *      is invalid or unopend so as to cause the caller to exit its loop
  69  *      asap, the assumption being that the loop is of the form
  70  *          while (!Lst_IsAtEnd (l)) {
  71  *                ...
  72  *          }
  73  *
  74  * Side Effects:
  75  *      None.
  76  *
  77  *-----------------------------------------------------------------------
  78  */
  79 Boolean
  80 Lst_IsAtEnd(Lst l)
  81 {
  82     List list = l;
  83
  84     return (!LstValid (l) || !list->isOpen ||
  85             (list->atEnd == Head) || (list->atEnd == Tail));
  86 }
  87