external/bsd/nvi/dist/ex/ex_undo.c

   1 /*      $NetBSD: ex_undo.c,v 1.3 2014/01/26 21:43:45 christos Exp $     */
   2 /*-
   3  * Copyright (c) 1992, 1993, 1994
   4  *      The Regents of the University of California.  All rights reserved.
   5  * Copyright (c) 1992, 1993, 1994, 1995, 1996
   6  *      Keith Bostic.  All rights reserved.
   7  *
   8  * See the LICENSE file for redistribution information.
   9  */
  10
  11 #include "config.h"
  12
  13 #include <sys/cdefs.h>
  14 #if 0
  15 #ifndef lint
  16 static const char sccsid[] = "Id: ex_undo.c,v 10.7 2001/06/25 15:19:21 skimo Exp  (Berkeley) Date: 2001/06/25 15:19:21 ";
  17 #endif /* not lint */
  18 #else
  19 __RCSID("$NetBSD: ex_undo.c,v 1.3 2014/01/26 21:43:45 christos Exp $");
  20 #endif
  21
  22 #include <sys/types.h>
  23 #include <sys/queue.h>
  24
  25 #include <bitstring.h>
  26 #include <limits.h>
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29
  30 #include "../common/common.h"
  31
  32 /*
  33  * ex_undo -- u
  34  *      Undo the last change.
  35  *
  36  * PUBLIC: int ex_undo __P((SCR *, EXCMD *));
  37  */
  38 int
  39 ex_undo(SCR *sp, EXCMD *cmdp)
  40 {
  41         EXF *ep;
  42         MARK m;
  43
  44         /*
  45          * !!!
  46          * Historic undo always set the previous context mark.
  47          */
  48         m.lno = sp->lno;
  49         m.cno = sp->cno;
  50         if (mark_set(sp, ABSMARK1, &m, 1))
  51                 return (1);
  52
  53         /*
  54          * !!!
  55          * Multiple undo isn't available in ex, as there's no '.' command.
  56          * Whether 'u' is undo or redo is toggled each time, unless there
  57          * was a change since the last undo, in which case it's an undo.
  58          */
  59         ep = sp->ep;
  60         if (!F_ISSET(ep, F_UNDO)) {
  61                 F_SET(ep, F_UNDO);
  62                 ep->lundo = FORWARD;
  63         }
  64         switch (ep->lundo) {
  65         case BACKWARD:
  66                 if (log_forward(sp, &m))
  67                         return (1);
  68                 ep->lundo = FORWARD;
  69                 break;
  70         case FORWARD:
  71                 if (log_backward(sp, &m))
  72                         return (1);
  73                 ep->lundo = BACKWARD;
  74                 break;
  75         case NOTSET:
  76                 abort();
  77         }
  78         sp->lno = m.lno;
  79         sp->cno = m.cno;
  80         return (0);
  81 }