dist/nvi/ex/ex_undo.c

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